Search

Aim: Aimed to evaluate the diagnostic performance of preoperative MRI-based radiomic models for noninvasive prediction of lymphovascular space invasion (LVSI) in patients with cervical cancer (CC)., Materials and Methods: A systematic search of the PubMed, Embase, Web of Science, and Cochrane databases was conducted up to December 21, 2023. The quality of the studies was assessed utilizing the Radiomics Quality Score (RQS) system and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Pooled estimates of sensitivity, specificity, diagnostic odds ratio (DOR), and area under the curve (AUC) of the summary receiver operating characteristic curve (SROC) were computed. The clinical utility was evaluated using the Fagan nomogram. Heterogeneity was investigated and subgroup analyses were conducted., Results: Eleven studies were included, with nine studies reporting independent validation sets. In the training sets, the pooled sensitivity, specificity, DOR, and AUC of SROC were 0.81 (95% CI: 0.75-0.85), 0.78 (95% CI: 0.73-0.83), 15 (95% CI: 11-20), and 0.86 (95% CI: 0.79-0.92), respectively. For the validation sets, the overall sensitivity, specificity, DOR, and AUC of SROC were 0.79 (95% CI: 0.73-0.84), 0.73 (95% CI: 0.67-0.78), 10 (95% CI: 7-15), and 0.83 (95% CI: 0.71-0.91), respectively. The Fagan nomogram indicated good clinical utility. Subgroup analysis revealed that multi-sequence MRI-based models exhibited superior diagnostic performance compared to single-sequence MRI-based models in validation sets., Conclusion: This meta-analysis highlights the potential diagnostic efficacy of MRI-based radiomic models for predicting LVSI in CC. Nevertheless, large-sample, multicenter studies are still warranted, and improvements in the standardization of radiomics methodology are necessary., (Copyright © 2024 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Fatigue of temporomandibular joint (TMJ) tissues reflects the effects of magnitude (energy density; ED) and frequency of loading (jaw muscle duty factor; DF). This observational study measured these variables and tested for differences in mechanobehavior scores (MBS = ED 2 × DF) and component variables in subjects with and without TMJ disc displacement (±D). In accordance with Institutional Review Board and STROBE guidelines, written informed consent was obtained, and examination and imaging protocols identified eligible adult subjects. Specifically, magnetic resonance imaging was used to assign subjects' TMJs to ±D groups. Subjects were trained to record in-field jaw muscle activities, from which DFs (percentage of recording time) were determined. EDs (mJ/mm 3 ) were estimated using modeled TMJ loads and in vivo dynamic stereometry. Multivariate analysis of variance, post hoc independent t tests, and K-means cluster analysis identified significant group differences ( P < 0.05). Of 242 individuals screened, 65 females (TMJs: 78 +D, 52 -D) and 53 males (TMJs: 39 +D, 67 -D) participated. Subjects produced 312 daytime and 319 nighttime recordings of average duration 6.0 ± 0.2 h and 7.6 ± 0.1 h, respectively, and 219 (114 right, 105 left) intact dynamic stereometry recordings. Average EDs were 2-fold and significantly larger in +D than -D TMJs ( P < 0.0001). DFs were on average 3-fold larger during the daytime versus nighttime for both masseter and temporalis muscles and 1.8- and 3.0-fold larger for the masseter versus temporalis muscle during the daytime and nighttime, respectively. Daytime masseter MBSs for +D TMJs in females were the largest overall at 621 ± 212 (mJ/mm 3 ) 2 % and 2- to 43-fold larger versus -D TMJs in both sexes during daytime and nighttime. Cluster analysis ( P < 0.0001) identified groups 2 and 3, which comprised 87% +D TMJs and had average MBSs 21-fold larger than group 1. The results show MBS as a potential biomarker to predict homeostasis versus progression or reversal of degenerative TMJ structural changes., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background and Purpose: While three-dimensional susceptibility-weighted imaging has been widely suggested for intracranial vessel imaging, hemorrhage detection, and other neuro-diseases, its relatively long scan time has necessitated the clinical verification of recent progresses of fast imaging techniques. Our aim was to evaluate the effectiveness of brain SWI accelerated by compressed sensitivity encoding to identify the optimal acceleration factors for clinical practice., Materials and Methods: Ninety-nine subjects, prospectively enrolled from 5 centers, underwent 8 brain SWI sequences: 5 different folds of compressed sensitivity encoding acceleration (CS2, CS4, CS6, CS8, and CS10), 2 different folds of sensitivity encoding acceleration (SF2 and SF4), and 1 without acceleration. Images were assessed quantitatively on both the SNR of the red nucleus and its contrast ratio to the CSF and, subjectively, with scoring on overall image quality; visibility of the substantia nigra-red nucleus, basilar artery, and internal cerebral vein; and diagnostic confidence of the cerebral microbleeds and other intracranial diseases., Results: Compressed sensitivity encoding showed a promising ability to reduce the acquisition time (from 202 to 41 seconds) of SWI while increasing the acceleration factor from 2 to 10, though at the cost of decreasing the SNR, contrast ratio, and the scores of visual assessments. The visibility of the substantia nigra-red nucleus and internal cerebral vein became unacceptable in CS6 to CS10. The basilar artery was well-distinguished, and diseases including cerebral microbleeds, cavernous angiomas, intracranial gliomas, venous malformations, and subacute hemorrhage were well-diagnosed in all compressed sensitivity encoding sequences., Conclusions: Compressed sensitivity encoding factor 4 is recommended in routine practice. Compressed sensitivity encoding factor 10 is potentially a fast surrogate for distinguishing the basilar artery and detecting susceptibility-related abnormalities (eg, cerebral microbleeds, cavernous angiomas, gliomas, and venous malformation) at the sacrifice of visualization of the substantia nigra-red nucleus and internal cerebral vein., (© 2022 by American Journal of Neuroradiology.)

Aim: To assess the feasibility and preliminary diagnostic performances of relaxation times derived from synthetic magnetic resonance imaging (syMRI) for differentiating nasopharyngeal carcinoma from nasopharyngeal benign lymphoid hyperplasia, and to assess the influence of tissue segmentation method on relaxation estimates., Materials and Methods: Fifty participants with nasopharyngeal carcinoma (NPC) and 40 participants with benign hyperplasia (NPH) who underwent syMRI examination were enrolled prospectively. T1, T2, and proton density (PD) values were obtained from four different regions of interest (ROIs), namely, partial-section, single-section, three-sections, and whole-lesion. The metrics between NPC and NPH or among different ROIs were compared using Student's t-test or one-way ANOVA. The area under curve (AUC) was calculated to assess the performance of metrics obtained from different ROIs to differentiate NPC and NPH., Results: The T1, T2, and PD values for NPH were significantly higher than those for NPC, regardless of the type of ROI used, except for the PD value obtained from the whole-lesion ROI. The T2 values obtained from the single-section ROI showed the highest diagnostic accuracy in distinguishing NPC from NPH, with an AUC of 0.894, sensitivity of 0.900, and specificity of 0.800. Additionally, the T1, T2, and PD values for nasopharyngeal lesions showed no statistical difference among different kinds of ROI, except for the difference in T1 value between partial-section and other methods., Conclusion: Quantitative analysis of syMRI has the potential to distinguish NPC from NPH. Moreover, different types of ROI showed limited influence on the relaxation time estimation for nasopharyngeal lesions., (Copyright © 2020 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objectives: To evaluate the effect of peri-prostatic adipose tissue (PPAT) measurements using preoperative MRI on the prediction of prostate cancer (PCa) aggressiveness in men undergoing radical prostatectomy (RP)., Methods: We performed a retrospective study on 179 consecutive patients receiving RP from June 2016 to October 2018. Clinical characteristics were collected. PPAT measurements including peri-prostatic fat area (PPFA) and peri-prostatic fat area to prostate area (PA) ratio (PPFA/PA) were calculated by MRI. Multivariable logistic regression analysis was performed to identify independent predictors of PCa lymph node metastasis (LNM). The predictive performance was estimated through ROC curves. Nomograms were created based on the predictors., Results: Pathologic Gleason score positively correlated with digital rectal examination (DRE), PSA, PPFA/PA, P504S, and Ki-67 (all P < 0.05). ROC curves revealed that high PPFA and high PPFA/PA were associated with LNM (both P < 0.05). Multivariate analysis revealed that high PPFA/PA, pathologic Gleason score, pT stage, and Ki-67 were independently predictive of LNM. The nomograms were created and the C-index was 0.945., Conclusions: PPFA/PA is an independent predictor for LNM along with Gleason score, pT stage, and Ki-67. PPFA/PA may help predict LNM in men undergoing RP, thus providing adjunctive information for therapeutic strategy and prognosis.

Aim: To identify and evaluate the efficiency of the most commonly used parameters applied to gadoxetate disodium (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for liver fibrosis (LF) staging., Materials and Methods: Literature searches of PubMed, Web of Science, Embase, and MEDLINE databases from January 2004 to August 2018 were conducted. The applied parameters during imaging were noted and summarised. Studies using the most commonly used parameter were included. Extractive data were combined as pooled weighted mean difference (WMD) to determine the benefits in LF staging. The pooled sensitivity, specificity, and summary receiver operating characteristics (SROC) curve were calculated., Results: Among 57 relevant studies, the contrast enhancement index (CEI) was a relatively commonly used parameter. It was calculated as SI post /SI pre , where SI post and SI pre are the liver-to-muscle signal intensity ratios in the hepatocyte phase and pre-enhanced images, respectively. Six studies were included. F0 was regarded as normal liver, F1 as mild LF, F2 as moderate LF, and F3 and F4 as advanced LF. Comparisons of WMD revealed significant differences between F1-2 and F3-4. For stage ≥F1, the pooled sensitivity, specificity, and areas under SROC curve were 0.58, 0.84, and 0.85, respectively; the corresponding values for ≥F2 were 0.57, 0.68, and 0.76, while those for ≥F3 were 0.61, 0.75, and 0.72., Conclusion: The methodology and parameters used for Gd-EOB-DTPA-enhanced MRI for LF staging are diverse, but the CEI was a relatively common parameter. Overall, there is evidence to support use of CEI, but more evidence from larger studies is needed., (Copyright © 2019 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objective: To investigate magnetic resonance imaging (MRI) characteristic and differential diagnostic keypoints of common sellar regional cystic lesions with the purpose of improving differential diagnostic accuracy. Methods: In total, 174 cases of the pathologically diagnosed cystic lesions in sellar region between March 2016 and June 2019 were included in the current retrospective analysis. These cases included Rathke's cleft cyst ( n =68), craniopharyngioma ( n =48), pituitary adenoma ( n =56) and arachnoid cyst ( n =2) in the sellar region. The position, texture and morphology of leisions, signal of cystic and solid part, invasion of surrounding tissues and maximum diameter of cysts on the MRI images were evaluated and compared between different groups. SPSS 25.0 software was used for statistical analysis. Results: There were several specific changes on several MRI sequences in Rathke's cleft cysts, craniopharyngioma and pituitary adenoma groups. For Rathke's cleft cysts, round shape, rare polycystic structure, lack of solid part and maximum diameter of cysts which was significantly less than that of craniopharyngioma and pituitary adenoma groups ((17.37±6.12) mm vs (30.29±13.51) mm vs (28.18±11.13) mm, t value was 6.680, 5.838, respectively, all P <0.05), were favorable diagnostic criteria. While, the intracystic nodules were mostly found in craniopharyngioma. There was no high signal intensity in cystic wall on T1WI and T2WI of pituitary adenoma. MRI signal of arachnoid cyst in sellar region was basically the same as CSF signal, with low signal intensity on T1WI and DWI, high signal intensity on T2WI, without enhanced signal. Conclusions: Common sellar regional cystic lesions showed characteristic manifestations on different MRI sequences. Valuable information in the morphology, MRI signal intensity, maximum diameter measurements may improve accuracy of differential diagnosis for sellar regional cystic lesions.

Objective: To preliminarily study on the possible mechanism of cerebral cortical dysfunction pattern after anterior cruciate ligament (ACL) preservation reconstruction with autologous tendon through resting-state functional magnetic resonance imaging (fMRI). Methods: From June 2015 to February 2019, 18 patients (10 males and 8 females with an average age of (36±10) years) with left anterior cruciate ligament rupture and treated with arthroscopic preservation reconstruction with autologous tendon were enrolled in this study, and 17 comparable healthy controls were included in Tongji Hospital of Tongji University. fMRI was performed after the postoperative period (2 to 12 weeks). The fMRI data were preprocessed by SPM8 software package and RESTplus software. The amplitude of low-frequency fluctuation (ALFF) and the fractional amplitude of low-frequency fluctuation (fALFF) in those two groups were calculated. Two-sample t -test was performed on ALFF and fALFF of the two groups, and multiple test corrections were performed by using AlphaSim. These methods were used for contrast studies on the characteristic activities of the brain dysfunction. Results: Compared with those in the control, ALFF in the central cingulate gyrus (cingulum&#95;mid&#95;bilateral), involving the auxiliary movement zone (supp&#95;motor&#95; area) were significantly higher in the patients ( P< 0.01 before correction, P< 0.05 after AlphaSim correction). The fALFF in activation cluster 1 was significantly higher in the right central gyrus (postcentral&#95;R), the right lower lobule (parietal&#95;inf&#95;R), and the right upper margin (supramarginal&#95;R) in the patients than that in the normal control group, respectively ( P< 0.01 before correction, P< 0.05 after AlphaSim correction); the fALFF in activation cluster 2 in the right central cingulate gyrus (cingulum&#95;mid&#95;R), involving the right auxiliary movement zone (supp&#95;motor&#95;area&#95;R) was significantly higher in the patients than that in the normal control group, respectively ( P< 0.01 before correction, P< 0.05 after AlphaSim correction). Conclusion: The patients' cerebrum cortical function associated with the kinesthesis and their regulations are abnormally changed after anterior cruciate ligament preservation reconstruction with autologous tendon.

Aim: To investigate whether there is an optimal time in the menstrual cycle to obtain the best image quality of uterine zonal structures with high-field magnetic resonance imaging (MRI)., Materials and Methods: Thirty-eight normal volunteers with regular menstrual cycles underwent pelvic 3 T high-resolution T2-weighted three-dimensional (3D) turbo spin echo (TSE) with variable flip angle MRI examinations during the menstrual phase (MP), follicular phase (FP), peri-ovulatory phase (OP), and luteal phase (LP). Two radiologists blinded evaluated the boundary sharpness of the three zonal structures of the uterine corpus and cervix on mid-sagittal images using a three-point Likert-scale. The signal intensity (SI) on T2-weighted sequences of each zonal structure was measured and the ratio between the SI of adjacent structures was calculated. Paired Wilcoxon's test and repeated measurement analysis of variance were used to investigate the differences among the four phases., Results: No variation during the menstrual cycle was found in 10.5% (4/38) of volunteers and their boundaries were all well-defined. The OP exhibited the clearest boundaries of the corpus zonal structures. For the endometrium to junctional zone, mean scores of boundary sharpness from high to low were 3 (OP), 2.97 (FP), 2.76 (LP), 2.74 (MP); that for the junctional zone to myometrium were 2.76 (OP), 2.42 (FP), 2.32 (LP), 2.11 (MP); which were consistent with the SI ratio results. The results for the cervix showed no statistical difference during the menstrual cycle (p>0.05), and was well-defined throughout., Conclusions: The OP is recommended as the best phase to investigate zonal-related uterine corpus diseases due to the best contrast. For cervical diseases, imaging could be performed when necessary at any time point, due to the limited influence of menstrual phases on cervical zone delineation., (Copyright © 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objective: This study aimed at exploring and contrasting the clinical significances and values of MRI, CT and contrast-enhanced ultrasonography in FIGO staging of cervical carcinoma., Patients and Methods: The contrast-enhanced ultrasonography, CT and MRI imaging data of 348 patients with cervical carcinoma confirmed by clinical pathology were analyzed retrospectively and contrasted with pathological findings., Results: The total accuracy of MRI in cervical carcinoma staging was 79.89% (278/348), and the diagnostic accuracy of MRI in stage IB, stage II, stage III and stage IV of cervical carcinoma was 74.29% (26/35), 75.74% (153/202), 85.25% (52/61), 94.00% (47/50), respectively. The total accuracy of CT in cervical carcinoma staging was 73.28% (255/348), and the diagnostic accuracy of CT in stage IB, stage II, stage III and stage IV of cervical carcinoma was 60.00% (21/35), 69.80% (141/202), 78.69% (48/61), 94.00% (45/50), respectively. The total accuracy of contrast-enhanced ultrasonography in cervical carcinoma staging was 57.47% (200/348), and the diagnostic accuracy of contrast-enhanced ultrasonography in stage IB, stage II, stage III and stage IV of cervical carcinoma was 37.14% (13/35), 50.99% (103/202), 70.49% (43/61), 82.00% (41/50), respectively. The accuracy of MRI in the diagnosis of stage IB, stage II of cervical carcinoma was higher than that of CT and contrast-enhanced ultrasonography (p<0.05), and the diagnostic accuracy of CT was higher than that of contrast-enhanced ultrasonography (p<0.05). The differences among the three methods were statistically significant., Conclusions: According to the results of pathological sections, there were statistically significant differences among the sensitivity and specificity of MRI, CT and contrast-enhanced ultrasonography in the diagnosis of stage IB and stage II (p<0.05). MRI has high diagnostic values in the differentiation and diagnosis of cervical carcinoma staging.

Aim: To investigate the accuracy of two semi-automatic segmentation measurements based on magnetic resonance imaging (MRI) three-dimensional (3D) Cube fast spin echo (FSE)-flex sequence in phantoms, and to evaluate the feasibility of determining the volumetric alterations of orbital fat (OF) and total extraocular muscles (TEM) in patients with thyroid-associated ophthalmopathy (TAO) by semi-automatic segmentation., Materials and Methods: Forty-four fatty (n=22) and lean (n=22) phantoms were scanned by using Cube FSE-flex sequence with a 3 T MRI system. Their volumes were measured by manual segmentation (MS) and two semi-automatic segmentation algorithms (regional growing [RG], multi-dimensional threshold [MDT]). Pearson correlation and Bland-Altman analysis were used to evaluate the measuring accuracy of MS, RG, and MDT in phantoms as compared with the true volume. Then, OF and TEM volumes of 15 TAO patients and 15 normal controls were measured using MDT. Paired-sample t-tests were used to compare the volumes and volume ratios of different orbital tissues between TAO patients and controls., Results: Each segmentation (MS RG, MDT) has a significant correlation (p<0.01) with true volume. There was a minimal bias for MS, and a stronger agreement between MDT and the true volume than RG and the true volume both in fatty and lean phantoms. The reproducibility of Cube FSE-flex determined MDT was adequate. The volumetric ratios of OF/globe (p<0.01), TEM/globe (p<0.01), whole orbit/globe (p<0.01) and bone orbit/globe (p<0.01) were significantly greater in TAO patients than those in healthy controls., Conclusion: MRI Cube FSE-flex determined MDT is a relatively accurate semi-automatic segmentation that can be used to evaluate OF and TEM volumes in clinic., (Copyright © 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Aim: To evaluate the performance of the combination of diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) for differentiating radiologically indeterminate malignant from benign orbital masses., Materials and Methods: Sixty-five patients with orbital masses (36 benign and 29 malignant) underwent DW and DCE MRI examinations for pre-treatment evaluation. The apparent diffusion coefficient (ADC) was derived from DW imaging data using the mono-exponential model. The volume transfer constant (K trans ), the flux rate constant between the extravascular extracellular space and the plasma (K ep ), and the extravascular extracellular volume fraction (V e ) were calculated using modified Tofts model. Differences in quantitative metrics were tested using independent-samples t test. Receiver operating characteristic (ROC) curve analyses were used to determine and compare the diagnostic ability of each significant metric., Results: The malignant group demonstrated significantly lower ADC (0.711±0.260 versus 1.187±0.389, p<0.001) and higher K ep values (1.265±0.637 versus 0.871±0.610, p=0.008) than the benign group. Optimal diagnostic performance (area under the ROC curve [AUC], 0.941; sensitivity, 0.966; specificity, 0.917) could be achieved using combined ADC and K ep values as the diagnostic index. The diagnostic performance of the combination of ADC and K ep was significantly better than K ep alone (p=0.006). Compared with ADC alone, combined ADC and K ep values also showed higher AUC (0.941 versus 0.898), although the difference did not reach statistical significance (p=0.220)., Conclusion: K ep and ADC could help to differentiate radiologically indeterminate malignant from benign orbital masses. The combination of DW and DCE MRI might improve the differentiating performance., (Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Background and Purpose: Susceptibility MR imaging contrast variations reflect alterations in brain iron and myelin content, making this imaging tool relevant to studies of multiple sclerosis lesion heterogeneity. In this study, we aimed to characterize the relationship of high-field, susceptibility contrasts in multiple sclerosis lesions to clinical outcomes., Materials and Methods: Twenty-four subjects with multiple sclerosis underwent 7T MR imaging of the brain, disability examinations, and a fatigue inventory. The inverse of T2* relaxation time (R2*), frequency, and relative susceptibility (from quantitative susceptibility mapping) were analyzed in 306 white matter lesions., Results: Most lesions were hypointense on R2* (88% without a rim, 5% with). Lesions that were hyperintense on quantitative susceptibility mapping were more frequent in relapsing-remitting than in progressive multiple sclerosis (54% versus 35%, P = .018). Hyperintense lesion rims on quantitative susceptibility maps were more common in progressive multiple sclerosis and patients with higher levels of disability and fatigue. Mean lesion R2* was inversely related to disability and fatigue and significantly reduced in progressive multiple sclerosis. Relative susceptibility was lower in lesions in progressive multiple sclerosis (median, -0.018 ppm; range, -0.070 to 0.022) than in relapsing-remitting MS (median, -0.010 ppm; range, -0.062 to 0.052; P = .003)., Conclusions: A progressive clinical phenotype and greater disability and fatigue were associated with lower R2* and relative susceptibility values (suggestive of low iron due to oligodendrocyte loss) and rimmed lesions (suggestive of chronic inflammation) in this multiple sclerosis cohort. Lesion heterogeneity on susceptibility MR imaging may help explain disability in multiple sclerosis and provide a window into the processes of demyelination, oligodendrocyte loss, and chronic lesion inflammation., (© 2016 by American Journal of Neuroradiology.)

Objective: To describe the radiological and clinical features of adult non-puerperal mastitis and to determine the most accurate method of preventing unnecessary surgical procedures., Methods: Clinical and imaging findings were retrospectively reviewed in 51 females with non-puerperal mastitis, which was confirmed by biopsy/surgical pathology. All 51 patients had pre-operative MRI; 45 patients also had sonograms and 25 also had mammograms, pre-operatively., Results: Of the 51 cases with non-puerperal mastitis, 94.1% (48/51) were confirmed as having acute or chronic inflammation, and the other 3 had plasma cell mastitis; areola papillaris inflammation was found in 39.2% (20/51) of the cases. Overall, 6 of the 25 cases that were examined with mammography and 2 of the 45 cases that were examined with sonography appeared normal, but all 51 lesions were positively identified on MRI. Asymmetrical density (12/25) on mammograms and solitary or separated/contiguous, clustered, hypoechoic mass-like lesions (31/45) on ultrasound were the most common signs of non-puerperal mastitis. On enhanced MRI, 90.2% (46/51) of patients showed non-mass-like enhanced lesions. Multiple regional enhancements in the pattern of distribution (32/46) and separated or contiguous, clustered, rim-like enhancements in the pattern of internal enhancement (29/46) were the most common manifestations in non-mass-like enhanced lesions. Of the 51 patients, mastitis Type 1 and Type 2 in the time-signal intensity curve were detected in 47.1% and 51.0% of the patients, respectively. The breast imaging reporting and data system categories with the highest number of patients were Category 0 (9/25) on mammography, Category 4a on sonography (18/45) and Category 4a on MRI (29/51)., Conclusion: The findings from mammography and ultrasound are non-specific; therefore, using MR can be helpful in the diagnosis, especially in the presence of non-mass-like enhancements that are multiple, regional, separated, or contiguous, clustered and rim-like., Advances in Knowledge: Mastitis is often neglected because of the lack of typical clinical signs and symptoms. This study has assessed and described the clinical features and imaging findings of adult non-puerperal mastitis on mammograms, sonograms and MRI and found that MRI is more specific in the diagnosis of disease.

Computational models of the heart at various scales and levels of complexity have been independently developed, parameterised and validated using a wide range of experimental data for over four decades. However, despite remarkable progress, the lack of coordinated efforts to compare and combine these computational models has limited their impact on the numerous open questions in cardiac physiology. To address this issue, a comprehensive dataset has previously been made available to the community that contains the cardiac anatomy and fibre orientations from magnetic resonance imaging as well as epicardial transmembrane potentials from optical mapping measured on a perfused ex-vivo porcine heart. This data was used to develop and customize four models of cardiac electrophysiology with different level of details, including a personalized fast conduction Purkinje system, a maximum a posteriori estimation of the 3D distribution of transmembrane potential, the personalization of a simplified reaction-diffusion model, and a detailed biophysical model with generic conduction parameters. This study proposes the integration of these four models into a single modelling and simulation pipeline, after analyzing their common features and discrepancies. The proposed integrated pipeline demonstrates an increase prediction power of depolarization isochrones in different pacing conditions., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Chewing-side preference (CSP) may be associated with dominant cerebral hemispheric organisation. However, little information exists regarding whether CSP is reflected by preferential activity in the opposite (to the CSP) cerebral hemisphere. The aim of this study was to investigate the effects of CSP on cerebral cortex response to bilateral tooth clenching. Sixteen right-handed participants with left (two men: 29·0±8·4 years old, six women: 32·3±4·8 years old) or right (four men: 31·0±6·1 years old, four women: 30·8±4·7 years old) CSP were scanned by functional magnetic resonance imaging during moderate levels of voluntary tooth clenching. The on-off sequence of scanning was 30 s of clenching (on) and 30 s of rest (off) a total of five times. The results showed that blood oxygen level-dependent signals in the contralateral (to the CSP) primary sensorimotor cortex increased more than in the ipsilateral primary sensorimotor cortex in participants with both left and right CSP (P≤0·001). The supplementary motor area was activated in participants with left (P≤0·001) but not right CSP. Activation of the inferior frontal gyrus and inferior parietal lobule was greater in participants with right versus left CSP (P≤0·001). Significant (P≤0·001) activation was observed in the parahippocampal gyrus in five of eight participants with left CSP, whereas no activation was observed in those with right CSP. These findings suggest a relationship between hemispheric dominance and CSP in the primary sensorimotor cortex responsible for bilateral tooth clenching., (© 2010 Blackwell Publishing Ltd.)

Aim: To investigate the ability of diffusion-weighted imaging (DWI) to predict and monitor the response of uterine cervical cancer to combined chemoradiation using apparent diffusion coefficients (ADCs)., Materials and Methods: Seventeen women (mean age 48.5 years) with uterine cervical cancer received conventional magnetic resonance imaging (MRI) and DWI prior to chemoradiation and after 1 and 2 months of therapy. A subgroup of eight also had MRI and DWI repeated after 15 days of therapy. Treatment response was determined according to changes in tumour size after 2 months of therapy and was classified as complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD). Pretreatment ADCs were compared between the different disease response groups, and dynamic changes of ADCs in each group were observed. Pearson's correlation test was calculated between those ADC parameters and tumour response., Results: Pretreatment ADCs for CR were significantly lower than those of PR (p=0.005). Negative correlation was found between pretreatment ADCs and percentage size reduction after 2 months of chemoradiation (p=0.016). The percentage ADC change after 1 month correlated positively with percentage size reduction after 2 months of therapy (p=0.021). ADCs after 15 days of therapy increased significantly compared with pretreatment ones (p=0.001); however, the longest tumour diameter showed no statistically significant change (p=0.078)., Conclusion: ADCs may have the potential to be used to predict and monitor the response of uterine cervical cancer to therapy., (2009 The Royal College of Radiologists.)

Summary: Generalized lymphangiomatosis is a rare congenital malformation of the lymphatics, characterized by cystic lesions in parenchymal organs and lytic bone lesions. In this report, we describe the radiographic and clinical features of 2 unusual cases of generalized lymphangiomatosis with bilateral orbital involvement.

Recent studies have shown that the surface of the brain is deformed by up to 20 mm after the skull is opened during neurosurgery, which could lead to substantial error in commercial image-guided surgery systems. We quantitatively analyze the intraoperative brain deformation of 24 subjects to investigate whether simple rules can describe or predict the deformation. Interventional magnetic resonance images acquired at the start and end of the procedure are registered nonrigidly to obtain deformation values throughout the brain. Deformation patterns are investigated quantitatively with respect to the location and magnitude of deformation, and to the distribution and principal direction of the displacements. We also measure the volume change of the lateral ventricles by manual segmentation. Our study indicates that brain shift occurs predominantly in the hemisphere ipsi-lateral to the craniotomy, and that there is more brain deformation during resection procedures than during biopsy or functional procedures. However, the brain deformation patterns are extremely complex in this group of subjects. This paper quantitatively demonstrates that brain deformation occurs not only at the surface, but also in deeper brain structure, and that the principal direction of displacement does not always correspond with the direction of gravity. Therefore, simple computational algorithms that utilize limited intraoperative information (e.g., brain surface shift) will not always accurately predict brain deformation at the lesion.

We retrospectively compared the costs and benefits of brain tumor resection in the conventional operating room (cOR) with the interventional magnetic resonance (iMR) suite from 1993-1998. Comparisons were made for adults (diagnosis-related group (DRG) 001) and children (DRG 003) for length of stay (LOS), hospital charges and payments, hospital total direct and indirect costs, readmission rates, repeat resection (RR) interval, and net health outcome. Statistical analysis was with ANOVA, Dunnett's, and Bonferroni tests. For DRG 001, iMR LOS (3.7 days (d)) was 54.9% shorter than for cOR (8.2 d) for first resections (FR) (P < 0.001) and RR (6.0 vs. 8.7 d (31.0%), P < 0.05). IMR hospital charges were 12.2% lower ($4063) for FR and 4.1% lower ($922) for RR than for cOR. Total iMR hospital costs were 14.4% lower ($3415) than for cOR for FR and 3.3% lower ($723) than costs for RR. Cost-to-charge ratio (c/c) for FR was 69.6% (iMR) and 71.4% (cOR) and for RR 70.9% (iMR) and 71.1% (cOR). For DRG 003, iMR LOS (4.5 d) was shorter than for cOR (14.1 d, P < 0.001) for FR and for RR (8.0 vs. 13.3 d). IMR hospital charges were 43.8% lower than for cOR for FR (P < 0.05) and RR. The iMR costs were lower for FR (46.4%, P < 0.01) and RR (44.7%) than cOR. IMR c/c was 71.4% and 74.8% for cOR. For RR, the iMR c/c was 72.8% and 73.9% for cOR. No RR have followed iMR surgery. COR RR rate was 20% in adults and 30% in children. The mean time from iMR surgery was 11.3 months in adults and 18.0 in children. For the cOR, the mean time to RR was 9.3 months in adults and 13.3 in children. This data suggests that iMR surgery improves net health outcomes by reduced LOS, reduced RR, and reduced hospital charges and costs.

To determine the frequency that high-field magnetic resonance (MR) imaging sequences influenced surgical decision making during intraoperative MR-guided surgery. From January 1997 to February 2001, 346 MR-guided procedures were performed using a 1.5-Tesla MR system (NT-ACS, Philips Medical Systems). This system can perform functional MR imaging (fMRI), diffusion weighted imaging (DWI), MR spectroscopy (MRS), MR angiography (MRA), and MR venography (MRV) in addition to T1-weighted, T2-weighted, and turbo FLAIR (fluid-attenuated inversion recovery) imaging. FMRI was used to determine areas of brain activation for language, motor function, and memory. DWI was utilized after tumor resection to exclude cerebral ischemia or infarction. MRS was obtained to identify areas of elevated choline that were suspected to correlate with tumor presence. MRA and MRV localized vascular structures adjacent to tumors prior to resection. The intraoperative procedures performed included 140 brain biopsies of which 82 utilized a trajectory guide and prospective stereotaxy. MRS was used in 42 biopsies (30%), of which 29 had turbo spectroscopic imaging (TSI) and 21 had single voxel spectroscopy (SVS). In all biopsy cases, diagnostic tissue was obtained. There were 103 tumor resections of which 18 (17%) had MRS. Functional MRI was used in 17 cases; 3 biopsies (2%) and 14 planned resections (14%). Speech function was localized in 3 cases, memory function in 3, and motor function in 11. In one case where the motor function of the tongue was intimately involved with a low-grade glioma, resection was not attempted. DWI was used in less than 10% of tumor resections. MRA and MRV were performed in 3 (3%) and 2 (2%) of tumor resections, respectively. The imaging capabilities (i.e., fMRI, DWI, MRA, MRV) associated with high-field intraoperative MR influenced surgical decision making primarily for tumor resections. MRS influenced target selection during brain biopsy.

Background and Purpose: During MR-guided neurosurgical procedures performed in a combined 1.5 Tesla MR-operating room (MR-OR), we have successfully implemented and validated a functional MRI (fMRI) scheme for efficiently localizing eloquent functional areas and assessing their proximity to a lesion volume immediately prior to the craniotomy., Methods: The fMRI examination consists of a dynamical blood oxygenation level dependent (BOLD) MR imaging technique and a task paradigm that is designed to activate the brain area of interest. The functional imaging technique was based on gradient-echo (GE) echo-planar imaging (EPI) (TR/TE = 2000-3000/40-50 msec). The motor task paradigm involves a periodic movement task, such as alternating between thumb and the other four fingers as a finger-tapping task, while the language involved a covert repeat of a series of words given as a task stimulus. While patient is performing the task, a dynamical fMRI was performed concurrently covering the volume of interest every 2 or 3 sec. Also, we have used a temporal series averaging (TSA) method for correcting the background drift in the raw fMRI signal, and developed a scheme for presenting fMRI results to neurosurgeons in an intuitive 3-dimensional volume-rendered display format., Results: By using the fMRI scheme, we have successfully performed sixteen fMRI examinations immediately prior to neurosurgery in the combined MR-OR on the same surgical table to localize various eloquent functional areas of interests. TSA was successful in reducing the background drift in the fMRI time course data, and the 3-dimensional volume-rendered display was proven effective in presenting the resulting brain activations to neurosurgeons. More importantly, in three representative cases (one biopsy and two tumor resections) presented, the information provided by fMRI have indeed contributed significantly in making the optimal surgical decisions prior to craniotomy., Conclusions: Intra-operative fMRI can be an indispensable tool for determining the location of a neighboring eloquent functional area of concern in reference to a targeted lesion. Information provided by fMRI has helped in improving the outcome and clinician confidence of all surgeries performed.

Calculations and experiments were used to examine the B(1) field behavior and signal intensity distribution in a 16-cm diameter spherical phantom excited by a 10-cm diameter surface coil at 300 MHz. In this simple system at this high frequency very complex RF field behavior exists, resulting in different excitation and reception distributions. Included in this work is a straightforward demonstration that coil receptivity is proportional to the magnitude of the circularly polarized component of the B(1) field that rotates in the direction opposite to that of nuclear precession. It is clearly apparent that even in very simple systems in head-sized samples at this frequency it is important to consider the separate excitation and reception distributions in order to understand the signal intensity distribution., (Copyright 2002 Wiley-Liss, Inc.)

Diffusion-weighted MR imaging (DWI) of two patients with carbon monoxide (CO) poisoning demonstrated white matter and cortical hyperintensities. In one patient, the changes on the FLAIR sequence were more subtle than those on DWI. The DWI abnormality in this patient represented true restriction. In the second patient, repeated exposure to CO caused restricted diffusion. DWI may be helpful for earlier identification of the changes of acute CO poisoning.

A practical MR imaging-based guidance/control methodology has been developed successfully and validated for improving the performance of stereotactic neurosurgerical procedures such as brain lesion biopsy. The use of the device and method in 40 routine MR-guided procedures has revealed its potential as an alternative approach. Superior to the traditional stereotactic systems, which rely on the old images, the new method, based on prospective guidance, can provide good and acceptable targeting accuracy in the presence of brain shift. Furthermore, the use of MR monitoring of the overall neurosurgical procedure provides another independent assurance for the success of a complicated surgery. The advantages of the new surgical guidance system and method are simple and compatible with the existing capabilities of conventional MR scanners. More importantly, it allows a more effective surgical guidance in the presence of brain shift during the typical neurosurgery. Another important advantage of the guidance method and device is the performance of a truly MR-guided neurosurgical procedure in a conventional, short bore high field MR scanner. Surgical procedures using the guidance system and method have been accepted by radiologists and neurosurgeons as an attractive MR-based stereotactic approach. It can be expected that this guidance scheme will be a useful addition to the MR-based stereotactic system for neurosurgery, and animal research, in which cumbersome stereotactic frames have been used.

High-field strength iMRI guidance is an effective tool for brain tumor resection. Although its use lengthens the average time for a craniotomy, the reward is a more extensive tumor excision compared with conventional neurosurgery without an increased risk to the patient (Table 4). Although intraoperative patient transfer into and out of the magnet is cumbersome, the possibility for complete resection, especially for a low-grade glioma, makes the effort worthwhile. The cost and technical support required for this system presently limits its use to only a few sites worldwide. As with any technology, further refinements will make this system less expensive and more attainable. Practical consideration aside, high-field strength iMRI is presently [table: see text] the most effective tool available for brain tumor resection. Because of its novelty, future studies are necessary to determine if this technology lowers the incidence of and extends the duration to tumor recurrence as the preliminary data in children suggests. These are the ultimate measures of efficacy for any brain tumor treatment. Based on the rapid advancement of technology, will today's high-field strength interventional magnet become tomorrow's low-field system? Very high-field strength designs may improve diagnostic capabilities through higher resolution, but their interventional applications may be hindered by increased sensitivity for clinically insignificant abnormalities and decreased specificity for clinically relevant lesions. As new technology is developed, clinicians must continue to explore and refine the existing high-field strength iMRI to make it cost-effective and widely applicable.

Neurobiopsy using intraoperative MR imaging represents a natural progression from stereotaxis in the method with which neurosurgeons perform brain biopsy.

Objective: The authors studied mild patients with AD with a visual learning paradigm to determine whether activations of medial temporal regions on fMRI differ in AD compared to nondemented individuals., Background: Changes in activation patterns of medial temporal lobe regions may serve as a biologic marker of altered brain function early in the course of AD., Methods: The authors studied eight healthy young subjects, eight late middle-age nondemented volunteers, and seven patients with mild AD. All subjects underwent fMRI scanning in which they viewed a set of geometric designs for 45 seconds. Changes in blood flow were analyzed by comparing the prestimulus fMRI signal with that present during the stimulus presentation., Results: Patients with AD, who had very poor recall of the geometric designs subsequently, showed increased blood flow (activation) during stimulus presentation only in a visual association area. Both the young and older nondemented subjects, all of whom had good recall of the designs, showed activations during stimulus presentation of the right entorhinal cortex, right supramarginal gyrus, right prefrontal regions, and left anterior-inferior temporal lobe. The younger and older nondemented subjects did not differ in fMRI activation patterns., Conclusions: Failure of activation in AD of either temporal lobe or prefrontal regions is consistent with established clinical-pathologic correlations in AD. fMRI may be useful in confirming a memory disorder diagnosis and also may be useful in detecting individuals with incipient dysfunction in learning as a result of disorders such as AD.

Background and Purpose: We sought to investigate whether the combination of conventional, diffusion-weighted, and perfusion-weighted MR imaging increases the diagnostic accuracy of balloon test occlusion of the internal carotid artery. We describe perfusion anomalies and patterns of enhancement seen in areas of altered brain perfusion during MR-monitored temporary balloon occlusion of the internal carotid artery., Methods: Nine patients underwent balloon occlusion testing under standard angiographic conditions with continuous clinical and EEG monitoring. One patient who failed the test by clinical criteria underwent an external carotid to internal carotid bypass operation, followed by a repeat balloon test occlusion, thereby bringing the total number of procedures to 10. Patients were further imaged at 1.5 T with perfusion- and diffusion-weighted imaging as well as with conventional noncontrast and contrast-enhanced turbo fluid-attenuated inversion recovery (FLAIR) and T1-weighted sequences., Results: Seven of 10 patients who tolerated unilateral carotid test occlusion without adverse clinical neurologic or EEG changes exhibited delayed first-pass transit of contrast material through the affected cerebral hemisphere, indicative of altered perfusion without significant concurrent cerebral blood flow or blood volume changes. Four of these patients and both symptomatic patients showed pial or subarachnoid contrast staining in areas of altered perfusion without abnormalities on diffusion-weighted images., Conclusion: Our findings indicate that MR perfusion-weighted imaging is safe and easily accomplished in a high-field-strength magnet and that contrast-enhanced turboFLAIR imaging may provide clinically useful MR imaging evidence of abnormal cerebral blood flow and subclinical ischemia.

An efficient magnetic resonance spectroscopic imaging (MRSI) or chemical shift imaging (CSI) technique based on multiple spin echoes (MSE) has been implemented, validated, and used in both phantom and in vivo MR-guided neurosurgical applications. The key concept of the method is to employ MSE to significantly speed up the data collection rate for mapping hydrogen-containing metabolites. Using an echo train length (ETL) of three per excitation to simultaneously fill three consecutive k-space areas, the total scan time for a spectroscopic image matrix size of 32 x 32 has been shortened to approximately 11 minutes. An interecho spacing time of 273 msec was used to null the phase anomalies of lactate double peaks due to the J-coupling. This allowed a sufficient long data sampling time to achieve 4 Hz spectral resolution. Performing CSI intraopertively during an MR-guided neurosurgical procedure was shown to be feasible at 1.5 T. More importantly, it was shown that more relevant information can be obtained regarding neurochemistry about a targeted lesion, in addition to conventional MR morphological imaging noninvasively. In 25 MR-guided neurosurgical cases, the alleviated choline signal has been found to be consistent with the existence of rapid tumor cell proliferation in the corresponding area. The actual neurobiopsy guided by the spectroscopic imaging method demonstrated that it could provide valuable information in specifying the optimal site in a biopsy procedure, especially in the case involving a nonenhancing tumor. The multiecho scheme has made the CSI technique efficient enough to be routinely used in MR-guided surgical procedures at 1.5 T and also allows the possibility of taking full advantage of MRI capability., (Copyright 2001 Wiley-Liss, Inc.)

Introduction: The posterior fossa in a child poses a considerable challenge to the neurosurgeon. MRI-guided surgery allows for real time interaction between imaging and the neurosurgeon, not permitted by frameless stereotaxy, and with higher resolution than ultrasound or CT., Materials and Methods: The University of Minnesota 1.5 T Phillips interventional MRI was used. From 1997 to 2000, nine posterior fossa intraoperative magnet cases out of eleven were pediatric. The mean age was 6.4 years and the median age 7. Seven midline craniotomies were performed, of which three were re-operations. Two were burr hole placements, one for cyst aspiration and P32 instillation, and the other for tumor biopsy., Results: Two tumors were predominantly in the fourth ventricle, four in the cerebellum, two in the brainstem, and one in the prepontine cystern. Four tumors were juvenile pilocytic astrocytomas, two were anaplastic astrocytomas, and one each was ependymoma, craniopharyngioma cyst, and medulloblastoma. Four patients had complete radiologic resection. Two had maximal resections limited by vital structures. P32 instillation and tumor biopsy were done in a single pass. Follow-up ranged from 3 months to 1.4 years. The cyst that was aspirated and had P32 instillation remains absent. The two mortalities were in the patients with medulloblastoma and anaplastic astrocytoma. There were no intra-operative mortalities. The other patient with anaplastic astrocytoma progressed. The remainder had stable imaging., Conclusion: MRI-guided surgery results in improved resection imaging and real-time needle guidance in tumor operations. Its value could lie in low-grade lesions, where maximal resection is most beneficial., (Copyright 2001 S. Karger AG, Basel)

Purpose: To describe prospective stereotaxy, a novel method of trajectory alignment that works in real-time., Materials and Methods: Prospective stereotaxy was used in minimally-invasive neurosurgical procedures in 74 patients since February 1999. This methodology differs from framed and frameless stereotaxy, both of which are based on retrospective data. Rather, prospective stereotaxy uses real-time MR images to align a surgical trajectory., Results: Phantom tests and clinical procedures in all patients were successfully performed using prospective stereotaxy. In all cases, surgical targets were accessed, and the diagnostic yield of neurobiopsy using prospective stereotaxy was 100%., Conclusion: Prospective stereotaxy is applicable to all cross-sectional imaging, and is particularly useful for MR- and CT-guided interventions. The method is simple, reproducible, and accurate in surgical targeting for neurobiopsy and electrode placement. It does not require cumbersome stereotactic frames or expensive optical detectors, and it offers immediate entry into the field of interventional MR with cylindrical MR scanners.

A thorough understanding of both the appearance and origin of metallic biopsy needle tip artifact in magnetic resonance imaging (MRI) as well as its interaction with various magnetic resonance (MR) sequence parameters is beneficial for its application in today's MR-guided therapeutic procedures. In a more practical setting, this investigation has focused on the characteristics of MR image artifacts associated with a finite-length metallic needle, specifically at the tip of a biopsy needle when it is approximately parallel to the main magnetic field. The image artifact at needle tip, which exhibits as a blooming ball-shaped signal void, was demonstrated and studied using MR imaging and numerical simulation employing the finite difference method (FDM). In order to understand the origin of this image artifact, a numerical model or simulation software based on the FDM has been developed specifically to solve for the field disturbance to a uniform magnetic field due to a finite-length metallic needle. The solution for magnetic field shows that the field disturbance is spatially localized at the needle tip. From the numerical results, simulated images were generated which were in a very satisfactory agreement MR imaging experiment. Results showed that the MR image artifacts associated with MR-compatible metallic biopsy needles are not only present due to the magnetic susceptibility difference between the needle and its surrounding tissue, but also predictable in routine MR-guided procedures, and the size of the image artifacts could be reduced if optimal imaging parameters were used. J. Magn. Reson. Imaging 2001;13:16-22., (Copyright 2001 Wiley-Liss, Inc.)

A combined MR suite and operating room (MR-OR) has been developed and extensively assessed for its use in a wide spectrum of therapeutic applications. Equipped with a 1.5 T short bore clinical MR scanner and standard neurosurgical OR equipment, in this MR surgical suite, surgeons can obtain intraoperative planar and volumetric MR images with superior soft tissue contrast and spatial resolution for surgical planning, guidance, and monitoring. Besides MR morphologic imaging capability, blood oxygen level-dependent functional MRI and proton MR spectroscopic imaging have been demonstrated intraoperatively in the same MR-OR to aid in surgical planning and guide tumor resections. A perspective surgical navigation device and remotely operated instrument have been developed and successfully used to assist surgeons in aligning and introducing biopsy needles under fluoroscopic MRI in brain biopsy procedures. Furthermore, surgical complications can be assessed immediately before the closure. There are numerous advantages offered by this unprecedented MR-guided surgical approach, most of which are demonstrated and presented herein. Since 1997, >270 neurosurgical cases (42% brain biopsies, 25% tumor resections, 11% functional neurosurgeries, 10% cyst drainages and shunt placements, and 12% others) have been performed in the MR-OR with a <1% overall complication rate. The tumor recurrence rate for the MR-guided surgical approach is significantly less than that of the conventional one. Exemplary neurosurgical cases that have been performed in the MR-OR suite within the last 24 months are included. Overall, this high magnetic field approach to the MR-guided minimally invasive surgical procedures has been shown to be practical and acceptable to neurosurgeons as well as to neuroradiologists for a wide range of neurosurgical and neuroradiologic applications.

Functional MRI (fMRI) based on blood oxygenation level dependent (BOLD) contrast can be used to detect hemodynamic responses to a broad range of stimuli. It however remains unclear in what fashion the BOLD response is a linear system, and how the impulse function differs with stimulation of varying duration. To address this question, fMRI using visual stimulation with a wide range of duration (0.5-12 s) was performed in six human volunteers. A strong linear correlation was shown on the full width at half maximum (r = 0.998) of the BOLD response curves and the area under the curves (r = 0.999) to the duration of stimulation. However, comparing the errors of the measured and predicted response curves, our results showed a poorer linearity at stimuli of shorter duration. By examining the impulse functions derived from different stimuli, based on the assumption that a linear convolution relationship existed, a higher differentiation was shown in the experiments with shorter stimuli (<3 s). Compared to the area under the impulse function derived from 12 s stimulation, with that obtained from 0.5, 1, 2, 3, 4, 8 s stimuli resulted in differences of 66.2, 33.5, 15.1, 5.4, 0.9, 7.9%, respectively. This study suggests a higher degree of nonlinearity in the BOLD signal changes due to stimuli of shorter duration, in agreement with earlier work.

Intraoperative magnetic resonance imaging (MRI) allows neurosurgeons to perform surgery interactively using magnetic resonance (MR) guidance. Low-field and high-field strength MRI has been developed and implemented for multiple neurosurgical procedures, including brain biopsies, craniotomies for resection of mass lesions, cyst drainages, laminectomies, thermal ablations, functional neurosurgery, and a variety of miscellaneous cases. Both technologies have the advantage over frameless neuronavigational systems of being able to perform near real-time imaging, which allows the surgeon to compensate for intraoperative brain shift. Intraoperative functional techniques such as MR spectroscopy, functional MRI, MR angiography and venography, and diffusion-weighted imaging, which have become routine at some high-field MR units, can significantly influence surgical decision making. The potential complications associated with intraoperative MR-guided neurosurgery are similar in incidence to those seen in the conventional neurosurgical operating room. However, the immediate recognition of such intraoperative complications with MRI should lead to improved outcomes and decreased medical costs. Untoward events associated with performing surgery in an MR environment are uncommon. Intraoperative MR-guided neurosurgery represents a natural progression from framed and frameless stereotactic techniques. Intraoperative MRI is still in its infancy, and the full capabilities of this technology have yet to be determined or implemented.

Since the spatial field non-linearity of gradient coils translates into image geometric distortion in MRI, in many applications, such as cardiac function analysis and interventional MR-based device tracking/guidance, where the precise geometric information is needed, the presence of geometric image distortion can not be simply ignored. To address the concern for geometric image distortion, we have developed and validated a general and efficient numerical technique for parameterizing the global image distortion for a bi-planar gradient coil as well as accomplishing image restoration as a post-imaging processing. This image correction methodology is based on a global distortion coordinate mapping function which can be systematically defined directly from the gradient field non-linearity in 3-dimension (3D) of a given gradient coil. The image correction was carried out in two steps: (1) map each pixel of the corrected image representation onto its distorted image according to the distortion mapping; (2) interpolate the pixel intensity in the distorted image using its neighboring points via a bi-linear interpolation procedure. The results showed clearly that the distortion correction method was robust in term of the capability of reducing image geometric distortion dramatically. Also it is shown that the magnetic field non-linearity or the image distortion of a typical bi-planar gradient coil can be adequately parameterized using a finite Taylor series expansion based on its design parameters. Furthermore, this image distortion correction method is very efficient in practice for performing 3D correction for any image orientation since a compact parameterized field expression contains non-zero terms.

Purpose: To investigate the challenges and benefits of magnetic resonance (MR) imaging during brain tumor resection., Materials and Methods: A short-bore 1.5-T MR system equipped with echo-planar-capable gradients was used in resection of brain tumors in 30 patients. MR sequences and need for contrast material enhancement were determined on the basis of the targeted lesion. MR images were acquired before, during, and after surgery. Tissue obtained at biopsy or excised as a result of intraoperative MR findings was examined histopathologically., Results: MR images of enhancing lesions proved to be the most challenging to interpret intraoperatively, and relative enhancement at the resection cavity boundary was not specific for residual tumor. The ability to detect residual tumor intraoperatively resulted in a radiologically complete resection in 24 (80%) of 30 patients. The frequency of complications was low, and no untoward effects related to the MR environment were observed., Conclusion: Intraoperative MR imaging provided valuable information on the completeness of resection, and resection progress was well demonstrated during surgery.

Objective: Interventional magnetic resonance imaging (MRI) allows neurosurgeons to interactively perform surgery using MRI guidance. High-field strength (1.5-T) imaging permits exceptional observation of intracranial and spinal pathological features. The development of this technology and its application to a variety of neurosurgical procedures are described., Methods: We report on the first 101 cases that were treated in the interventional MRI unit (between January 1997 and September 1998). These cases included 39 brain biopsies, 30 tumor resections, 9 functional neurosurgical cases, 8 cyst drainages, 5 laminectomies, and 10 miscellaneous cases. Patients ranged in age from 14 months to 84 years (median, 43 yr); 61 patients were male and 40 were female. Intraoperative functional techniques that were used to influence surgical decision-making included magnetic resonance spectroscopy, functional MRI, magnetic resonance angiography and venography, chemical shift imaging, and diffusion-weighted imaging. All surgery was performed using MRI-compatible instruments within the 5-gauss line and conventional instruments outside that line., Results: All 39 brain biopsies yielded diagnostic tissue. Of the 30 tumor resections, 24 (80%) were considered radiographically complete. The incidence of serious complications was low and was comparable to that associated with conventional operating rooms. One patient developed a Propionibacterium acnes brain abscess 6 weeks after surgery and another patient experienced Staphylococcus aureus scalp cellulitis after a brain biopsy, yielding an infection rate of less than 2%. No clinically significant hemorrhage was observed in immediate postoperative imaging scans, although one patient developed a delayed hematoma after a thalamotomy. One patient experienced a stroke after resection of a hippocampal tumor. No untoward events were associated with MRI-compatible instrumentation or intraoperative patient monitoring., Conclusion: High-field (1.5-T) interventional MRI is a safe and effective technology for assisting neurosurgeons in achieving the goals of surgery. Preliminary results suggest that the functional capabilities of this technology can yield data that can significantly influence intraoperative neurosurgical decision-making. The rates of serious complications, such as infection, associated with this new technology were low.

Background: Previous NIMH childhood onset schizophrenia (COS) anatomic brain MRI studies found progression of ventricular volume and other structural brain anomalies at 2-year follow up across mean ages 14 to 16 years. However, studies in adult patients generally do not show progression of ventricular volume or correlation of ventricular volume with duration of illness. To address issues of progression of brain anomalies in schizophrenia, this report extends previous studies to include a third longitudinal scan, uses a larger sample size, and includes measures of the amygdala and hippocampus., Methods: Volumes of the total cerebrum, lateral ventricles, hippocampus, and amygdala were quantified on 208 brain magnetic resonance imaging scans from 42 adolescents with COS (23 with one or more repeat scan) and 74 age- and gender-matched controls (36 with one or more repeat scan). A statistical technique permitting combined use of cross-sectional and longitudinal data was used to assess age-related changes, linearity, and diagnostic group differences., Results: Differential nonlinear progression of brain anomalies was seen during adolescence with the total cerebrum and hippocampus decreasing and lateral ventricles increasing in the COS group. The developmental curves for these structures reached an asymptote by early adulthood for the COS group and did not significantly change with age in the control group., Conclusions: These findings reconcile less striking progression of anatomic brain images usually seen for adult schizophrenia and complement other data consistent with time-limited, diagnostic-specific decreases in brain tissue. Adolescence appears to be a unique period of differential brain development in schizophrenia.

1. Interest in the morphologic development of the corpus callosum (CC) during childhood and adolescence stems from adolescent changes in cognitive functions subserved by the CC, reports of CC anomalies for a wide variety of childhood neuropsychiatric illnesses, and controversy regarding sexual dimorphism. 2. Characterization of the normal developmental pattern of the CC is hindered by enormous variability of its size. This is especially problematic for cross-sectional studies seeking to assess possible non-linear developmental curves. 3. To more accurately characterize developmental changes, a longitudinal brain magnetic resonance imaging study with subjects rescanned at approximately 2 year intervals was conducted resulting in 251 scans from 139 healthy children and adolescents. 4. Midsagittal area of the CC, especially the posterior regions, increased robustly from ages 5 to 18 years. 5. Although the genu of the CC was significantly larger in males there were no sex differences in mean area after adjustment for total cerebral volume and the growth patterns did not differ between sexes. 6. Analysis revealed a non-linear increase in the splenium, the most posterior region, with increases greatest in the younger years. 7. The results of this longitudinal study, in addition to confirming and extending previous cross-sectional reports, provide an increasingly accurate yardstick from which to assess pathological development.

Objective: Lesions within the brain are commonly sampled using stereotactic techniques. The advent of interventional magnetic resonance imaging (MRI) now allows neurosurgeons to interactively investigate specific regions, with exquisite observational detail. We evaluated the safety and efficacy of this new surgical approach., Methods: Between January 1997 and June 1998, 35 brain biopsies were performed in a high-field strength interventional MRI unit. All biopsies were performed using MRI-compatible instrumentation. Interactive scanning was used to confirm accurate positioning of the biopsy needle within the region of interest. Intraoperative pathological examination of the biopsy specimens was performed to verify the presence of diagnostic tissue, and intra- and postoperative imaging was performed to exclude the presence of intraoperative hemorrhage. Recently, magnetic resonance spectroscopic targeting was used for six patients., Results: Diagnostic tissue was obtained in all 35 brain biopsies and was used in therapeutic decision-making. Histological diagnoses included 28 primary brain tumors (12 glioblastomas multiforme, 9 oligodendrogliomas, 2 anaplastic astrocytomas, 2 astrocytomas, 1 lymphoma, and 1 anaplastic oligodendroglioma), 1 melanoma brain metastasis, 1 cavernous sinus meningioma, 1 cerebral infarction, 1 demyelinating process, and 3 cases of radiation necrosis. In all cases, magnetic resonance spectroscopy was accurate in distinguishing recurrent tumors (five cases) from radiation necrosis (one case). No patient sustained clinically or radiologically significant hemorrhage, as determined by intraoperative imaging performed immediately after the biopsy. One patient (3%) suffered transient hemiparesis after a pontine biopsy for investigation of a brain stem glioma. Another patient developed scalp cellulitis, with possible intracranial extension, 3 weeks after the biopsy; this condition was effectively treated with antibiotic therapy. Three patients were discharged on the day of the biopsy., Conclusion: Interventional 1.5-T MRI is a safe and effective method for evaluating lesions of the brain. Magnetic resonance spectroscopic targeting is likely to augment the diagnostic yield of brain biopsies.

Lesions within the brain are commonly sampled using stereotactic techniques. The advent of interventional magnetic resonance (MR) imaging now allows neurosurgeons to interactively investigate specific regions with exquisite visualization. We compared the safety and efficacy of this new surgical approach with stereotaxis. From February 1991 to June 1998, 134 stereotactic and 35 interventional MR-guided brain biopsies were performed. Stereotactic biopsies utilized preoperative scanning. Interactive scanning was used to confirm accurate positioning of the biopsy needle within the region of interest. Intraoperative pathologic examination of biopsy material was performed to verify the presence of diagnostic tissue in both biopsy groups. Intra- and postoperative MR imaging was obtained to exclude the presence of intraoperative hemorrhage. Recently, MR spectroscopic targeting has been utilized in 6 patients. In the stereotactic group, 129/134 (96%) biopsies were diagnostic. One patient had a transient hemiparesis after a brain stem biopsy and another suffered a fatal hemorrhage for a morbidity rate of 0.7% and a mortality rate of 0.7%. In reviewing 7,471 stereotactic biopsies, the morbidity was 3.5%, mortality 0.7% and diagnostic yield 91%. All 35 MR-guided brain biopsies were diagnostic (100%). MR spectroscopy was accurate in all cases in distinguishing recurrent tumor (5 cases) from radiation necrosis (1 case). One patient (3%) suffered a transient hemiparesis following a pontine biopsy and another patient (3%) developed a postoperative scalp cellulitis. No patient sustained a clinically or radiologically significant hemorrhage as determined by the immediate postbiopsy, intraoperative MR imaging. Interventional MR-guided brain biopsy is a safe and effective technique for evaluating lesions of the brain with morbidity and mortality rates comparable to those of stereotaxis. MR-guided biopsy appears to have a higher diagnostic yield than stereotaxis, which may reflect the ability to perform interactive, intraoperative scanning with that technique., (Copyright 2000 S. Karger AG, Basel)

Background: Interventional magnetic resonance (MR) imaging allows neurosurgeons to interactively perform surgery using MR guidance. High-field (1.5-Tesla) strength imaging provides exceptional visualization of intracranial and spinal pathology. The full capabilities of this technology for pediatric neurosurgery have not been defined or determined., Materials and Methods: From January 1997 through June 1998, 10 of 85 cases performed in the interventional MR unit were in the pediatric population (mean age 8.3, median 8, range 2-15 years). Procedures included 2 brain biopsies, 5 craniotomies for tumor, 2 thoracic laminectomies for syringomyelia, and placement of a reservoir into a cystic brainstem tumor. The biopsies and reservoir placement were performed using MR-compatible equipment. Craniotomies and spinal surgery were performed with conventional instrumentation outside the 5-Gauss magnetic footprint. Interactive and intraoperative imaging was performed to assess the goals of surgery., Results: Both brain biopsies were diagnostic for cerebral infarct and anaplastic astrocytoma and the reservoir was optimally placed within the tumor cyst. Of the 5 tumor resections, all were considered radiographically complete. One biopsy patient and 1 tumor resection patient experienced transient neurological deficits after surgery. The patient with the thoracic syrinx required reoperation when the syringosubarachnoid shunt migrated into the syrinx 3 months after initial placement. No patient sustained a postoperative hemorrhage. Tumor histologies found at craniotomy were craniopharyngioma, ganglioglioma, and 3 low-grade gliomas. No evidence of tumor progression has been seen in any of these patients at a mean follow-up of 5.3 (range 4-8) months. The goals of the procedure were achieved in all 10 cases. There were no untoward events experienced related to MR-compatible instrumentation or intraoperative patient monitoring, despite the present inability to monitor core body temperature., Conclusions: 1.5-Tesla interventional MR is a safe and effective technology for assisting neurosurgeons to achieve the goals of pediatric neurosurgery. Preliminary results suggest that surgical resection of histologically benign tumors is enhanced in the interventional MR unit. The incidence of surgically related morbidity is low.

Finite-sized high-performance planar magnetic field gradient coils in today's open configuration magnetic resonance imaging (MRI) systems have always been desirable for ever demanding imaging applications. We present a Lagrange multiplier technique for designing a minimum-energy gradient coil under a finite-size planar geometry constraint in addition to a set of magnetic field constraints. In this new design methodology, the surface current density on a finite size plane is represented by a two-dimensional (2-D) Fourier series expansion. Following the standard approach, we construct a functional F in terms of the stored magnetic energy and a set of field constraint points which are chosen over the desired imaging volume. Minimizing F, we obtain the continuous current density distribution for the finite-size planar gradient coil. Applying the stream function technique to the resulting continuous current distribution, the discrete current pattern can be generated. Employing the Biot-Savart law to the discrete current loops, the gradient magnetic field has been re-evaluated in order to validate the theory. Using this approach, we have been able to design a finite-size biplanar z-gradient coil which is capable of generating a gradient field of 40 mT/m @ 266 A. The excellent agreement between the analytical and numerical results has been achieved.

All image-guided neurosurgical systems that we are aware of assume that the head and its contents behave as a rigid body. It is important to measure intraoperative brain deformation (brain shift) to provide some indication of the application accuracy of image-guided surgical systems, and also to provide data to develop and validate nonrigid registration algorithms to correct for such deformation. We are collecting data from patients undergoing neurosurgery in a high-field (1.5 T) interventional magnetic resonance (MR) scanner. High-contrast and high-resolution gradient-echo MR image volumes are collected immediately prior to surgery, during surgery, and at the end of surgery, with the patient intubated and lying on the operating table in the operative position. In this paper we report initial results from six patients: one freehand biopsy, one stereotactic functional procedure, and four resections. We investigate intraoperative brain deformation by examining threshold boundary overlays and difference images and by measuring ventricular volume. We also present preliminary results obtained using a nonrigid registration algorithm to quantify deformation. We found that some cases had much greater deformation than others, and also that, regardless of the procedure, there was very little deformation of the midline, the tentorium, the hemisphere contralateral to the procedure, and ipsilateral structures except those that are within 1 cm of the lesion or are gravitationally above the surgical site.

A better understanding of the appearance of a biopsy needle as well as its interaction with various sequence parameters in MRI is beneficial for its application in interventional MRI. As an extension of previous researchers' contributions, we investigate the specific characteristics of MR image artifacts associated with the tip of a biopsy needle when it is approximately parallel to the main magnetic field. The origin of the needle tip artifact, which exhibits as a blooming ball, was studied using MRI techniques and numerical simulation using the finite element method (FEM). Satisfactory agreement between theory and experiment has been achieved. Results showed that the image artifacts associated with biopsy needle are present and dependent on imaging parameters, but the artifacts can be reduced if optimal imaging parameters were used. Images of actual human brain tumor biopsies performed using the same needle under MRI guidance and monitoring demonstrated this artifact.

The use of phase-encode grouping (PEG) allows acquisition of a complete cardiac cine in a single breath hold, eliminating respiratory artifacts and improving edge definition. One approach to quantitative magnetic resonance (MR) flow measurements in pulmonary, coronary, and renal arteries uses phase velocity mapping with a PEG, single breath-hold, cine technique. Phantom studies were designed to evaluate the accuracy of MR phase velocity mapping (MRV) with PEG in continuous and pulsatile flow measurements in small vessels. Experiments were performed on a 1.5-T MRI system and results were compared with those obtained by timed volume measurements and a transit-time ultrasound flowmeter. Flow velocity, pulsatile flow wave form, pulsing rate, and PEG size were varied. For continuous flow, MRV measured velocities correlated well with those calculated from timed volume measurements (r > 0.998) under mean spatial velocities ranging from 20-100 cm s-1. The temporal mean velocity difference between MRV and ultrasound flowmeter measurements was less than +/- 2.9 cms-1 under pulsatile flow conditions with PEG sizes of 5 or less, however, the mean velocity difference was > 7 cm s-1 for PEG sizes of 8 or more. Accurate MR velocity measurement with PEG in small vessels under conditions of pulsatile flow is possible if an appropriate PEG size is selected.