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[Purpose]To evaluate prevalence of subcutaneous fluid collection (SFC) in infectious thoracolumbar spondylodiscitis (SD) compared with control patients and to investigate correlation between volume changes of SFC and treatment response of SD. [Materials and methods]This retrospective study was approved by our institutional review board. From April 2011 to March 2012, 49 patients (24 SD and 25 non-SD patients) were enrolled. Prevalence of SFC was evaluated respectively for SD and non-SD patients using magnetic resonance imaging (MRI) on the sagittal short tau inversion recovery (STIR) imaging or fat-saturated T2-weighted imaging (T2WI), and compared. In SD patients with SFC, correlation was investigated between SFC volume on the 1st MRI and initial clinical status. The same analysis was conducted also for SFC volume changes from the 1st to 2nd or last MRI. [Results]SFC was found in 20 patients with SD (83.3%) and 3 non-SD patients (12%) with significant difference (p < .001). In 20 SD patients with SFC, 17 patients had follow-up MRI. For the 1st MRI, no significant correlation was found between volume of SFC and initial status of patients, including body weight, body mass index (BMI), white blood cell (WBC), and erythrocyte sedimentation rate (ESR). However, significant positive correlations were found between changes of C-reactive protein (CRP) and SFC volume from the 1st to 2nd as well as from the 1st to the last MRI (each p < .05). [Conclusion]SD patients had significantly higher prevalence of SFC than non-SD patients. Volume changes of SFC had significant correlation with changes of CRP, which can be used as an imaging marker for treatment response of SD on MRI.

[Objective]Positron emission tomography (PET)/computed tomography (CT) using 68Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid-D-Phe1-Tyr3-octreotide (DOTATOC) has been used to detect neuroendocrine tumors (NETs). The purpose of this study was to investigate the clinical efficacy of DOTATOC-PET/CT for detecting clinically suspected NETs when conventional imaging modalities were negative or inconclusive, in terms of additional value. [Methods]A total of 46 patients were analyzed retrospectively. Among them, 14 patients underwent a DOTATOC-PET/CT scan for detecting unknown primary tumors after histopathological confirmation of a NET at metastatic sites (group A): 7 patients for detecting metastasis or recurrence after surgery for NET because of their high hormone levels but with no recurrence detected by other imaging modalities (group B); the remaining 25 patients for detecting suspected NETs because their hormone levels were high with no history of histopathologically proven NET (group C). Additional information was assessed, according to each situation. [Results]In group A, unknown primary tumors were suspected by DOTATOC-PET/CT in 8 of 14 patients (gastrointestinal/pancreatic NET in 7 patients, prostatic cancer in 1 patient), but prostatic cancer was not confirmed by histopathology (i.e., false positive). In group B, DOTATOC-PET/CT depicted lesions in six of seven patients, including nodal metastasis (n = 5) and liver metastasis (n = 1). In group C, DOTATOC-PET/CT did not demonstrate any abnormal foci except in one case of pancreatic NET. Additional information was obtained in 50, 86, and 4 % of cases, in groups A, B, and C, respectively. [Conclusions]DOTATOC-PET/CT was useful for detecting NETs, especially when recurrence or metastases were suspected because of high hormone levels after surgery for a NET. It is unlikely, however, that additional information can be acquired in patients with no history of NET simply based on high hormone level

[Objectives]: The aim of this study was to assess the consistency and reproducibility of quantitative susceptibility mapping (QSM) at 3-T and 1.5-T magnetic resonance (MR) scanners. [Materials and Methods]: This study was approved by institutional ethics committee, and written informed consent was obtained. Twenty-two healthy volunteers underwent 2 examinations on different days. Each examination consisted of MR imaging on both 3-T and 1.5-T MR scanners. The data from both scanners and examination days were obtained, and QSM was calculated with STI Suite using 2 different algorithms-harmonic phase removal using laplacian operator (HARPERELLA) and a sophisticated harmonic artifact reduction for phase data (SHARP) method with a variable radius of the spherical kernel at the brain boundary (V-SHARP). We evaluated consistency of QSM between 3 T and 1.5 T and the reproducibility between the first and second examinations using 2-phase processing methods (HARPERELLA and V-SHARP). [Results]: Susceptibility values of regions of interests at 3 T were highly correlated with those at 1.5 T with good agreement (HARPERELLA, R2 = 0.838; V-SHARP, R2 = 0.898) (average difference, +/-1.96 SD; HARPERELLA, -0.012 +/- 0.046; V-SHARP, -0.002 +/- 0.034). Reproducibility analysis demonstrated excellent correlation between the first and second examination at both 3 T and 1.5 T for both algorithms (HARPERELLA at 3 T, R2 = 0.921; 1.5 T, R2 = 0.891; V-SHARP at 3 T, R2 = 0.937; 1.5 T, R2 = 0.926). Bland-Altman analysis showed excellent reproducibility for HARPERELLA (3 T, -0.003 +/- 0.032; 1.5 T, -0.003 +/- 0.038) and V-SHARP (3 T, -0.003 +/- 0.027; 1.5 T, -0.003 +/- 0.029). Susceptibility values of these 2 algorithms were highly correlated with good agreement (3T, R2 = 0.961; 1.5 T, R2 = 0.931) (3 T, 0.009 +/- 0.023; 1.5 T, -0.003 +/- 0.049). [Conclusions]: Quantitative susceptibility mapping with HARPERELLA and V-SHARP demonstrated good reproducibility at 3 T and 1.5 T, and QSM with V-SHARP d

The purpose was to compare capability of fluorine-18 fluorodeoxyglucose (FDG)-PET and thallium-201 (Tl)-SPECT for grading meningioma. This retrospective study was conducted as a case-control study under approval by the institutional review board. In the hospital information system, 67 patients (22 men and 45 women) who had both FDG-PET and Tl-SPECT preoperative examinations were found with histopathologic diagnosis of meningioma. The maximum FDG uptake values of the tumors were measured, and they were standardized to the whole body (SUVmax) and normalized as gray matter ratio (SUVRmax). Mean and maximum Tl uptake ratios (TURmean and TURmax, respectively) of the tumors were measured and normalized as ratios to those of the contralateral normal brain. Receiver-operating characteristic curve analyses of the 4 indexes were conducted for differentiation between low- and high-grade meningiomas, and areas under the curves (AUCs) were compared. Correlation coefficients were calculated between these indexes and Ki-67. Fifty-six meningiomas were classified as grade I (low grade), and 11 were grade II or III (high grade). In all 4 indexes, a significant difference was observed between low- and high-grade meningiomas (P<0.05). AUCs were 0.817 (SUVmax), 0.781 (SUVRmax), 0.810 (TURmean), and 0.831 (TURmax), and no significant difference was observed among the indexes. Their sensitivity and specificity were 72.7% to 90.9% and 71.4% to 87.5%, respectively. Correlation of the 4 indexes to Ki-67 was statistically significant, but coefficients were relatively low (0.273-0.355). Tl-SPECT, which can be used at hospitals without a cyclotron or an FDG distribution network, has high diagnostic capability of meningioma grades comparable to FDG-PET.

[Introduction] Quantitative values of CT attenuation, apparent diffusion coefficient (ADC), and standardized uptake value (SUV) were investigated for differentiation between pineal parenchymal tumors (PPTs) and germinomas. Differences in age, sex, and calcification pattern were also evaluated. [Methods] Twenty-three patients with PPTs and germinomas in 20 years were retrospectively enrolled under the approval of the institutional review board. CT attenuation, ADC, and SUV (20, 13, and 10 patients, respectively) were statistically compared between the two tumors. Differences in sex and patterns of calcification (“exploded" or “engulfed") were also examined. Mean patient ages were compared among three groups of pineoblastoma, pineal parenchymal tumor of intermediate differentiation, (PPTID) and pineocytoma and germinoma. [Results]None of the quantitative values of CT attenuation, ADC, and SUV showed significant differences between PPTs and germinomas (p > .05). However, there was a significant difference in age (p < .05) among the three groups of pineoblastoma (mean age ± standard deviation 7.0 ± 8.7 years), PPTID, and pineocytoma (53.7 ± 11.4 years) and germinoma (19.1 ± 8.1 years). Sex also showed significant differences between PPTs and germinomas (p = .039). Exploded pattern of calcification was found in 9 of 11 PPT patients and engulfed pattern in 7 of 9 patients with germinomas. No reverse pattern was observed, and the patterns of calcification were considered highly specific of tumor types.[Conclusions] None of the quantitative imaging values could differentiate PPTs from germinomas. Age, sex, and calcification patterns were confirmed useful in differentiating these tumors to some degree.

To examine the association between apparent diffusion coefficient (ADC), cellularity, and Ki-67 index in mucinous breast carcinoma (MBC) compared with invasive carcinoma of no special type (NST). ADC's ability to identify lesions with highly proliferating MBC was also examined.

Arterial spin labeling (ASL) has been developed into a useful technique that is capable of quantifying noninvasively local cerebral blood flow (CBF) using the water molecules in arterial blood as diffusible tracers. Pulsed ASL (PASL) is more strongly affected than continuous ASL (CASL) by cardiac pulsation, because the tag bolus is shorter than the cardiac cycle in most cases. No reports have yet clarified the effects of multiple cardiac phases on the quantification of CBF in PASL when triggering is used. Fourteen subjects participated in this study. Peripheral pulse-wave-triggered (PPWT)-ASL was performed at various time points at the carotid artery (delay 0 ms, second point, foot, peak and tail) and compared with nontriggered (NT)-ASL. Regions of interest (ROIs) were applied based on the anterior, middle and posterior cerebral artery (ACA, MCA, PCA) territories, and CBFs were compared among different time points and ROIs. PPWT-ASL strongly affects CBF values compared with NT-ASL in ACA and MCA territories, especially when measured at the foot of the carotid artery flow phase. CBF_NT was assumed to lie approximately between the minimum and maximum CBFs, with clear statistical significance in several ROIs at several time points of PPWT-ASL, and CBF_NT was assumed to resemble 'randomly triggered' PPWT-ASL. In conclusion, PPWT-ASL strongly affects CBF values compared with NT-ASL, particularly at the foot of the carotid artery flow in ACA and MCA territories.

The purpose of this study is to verify objectively the rate of slice omission during paging on picture archiving and communication system (PACS) viewers by recording the images shown on the computer displays of these viewers with a high-speed movie camera. This study was approved by the institutional review board. A sequential number from 1 to 250 was superimposed on each slice of a series of clinical Digital Imaging and Communication in Medicine (DICOM) data. The slices were displayed using several DICOM viewers, including in-house developed freeware and clinical PACS viewers. The freeware viewer and one of the clinical PACS viewers included functions to prevent slice dropping. The series was displayed in stack mode and paged in both automatic and manual paging modes. The display was recorded with a high-speed movie camera and played back at a slow speed to check whether slices were dropped. The paging speeds were also measured. With a paging speed faster than half the refresh rate of the display, some viewers dropped up to 52.4 % of the slices, while other well-designed viewers did not, if used with the correct settings. Slice dropping during paging was objectively confirmed using a high-speed movie camera. To prevent slice dropping, the viewer must be specially designed for the purpose and must be used with the correct settings, or the paging speed must be slower than half of the display refresh rate.

This study describes the first case of biliary peritonitis after radiofrequency ablation diagnosed by magnetic resonance (MR) imaging with gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA), a hepatocyte-specific MR imaging contrast agent. The image acquired 300 minutes after the administration of Gd-EOB-DTPA was useful to make a definite diagnosis and to identify the pathway of bile leakage. It is important to decide on the acquisition timing with consideration of the predicted location of bile duct injury.

[Background]With the technical advance of magnetic resonance imaging (MRI), we have been able to observe not only the small cranial nerves arising from the brain stem but also the branches of vertebrobasilar artery in the cerebellopontine angle (CPA) cistern. [Purpose]The purpose was to demonstrate the courses and configurations of the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA) branch including the internal auditory artery in the CPA cistern and evaluate the relationship between the facial–vestibulocochlear (VIIth–VIIIth) nerves and AICA/PICA on high-resolution, thin-slice, three-dimensional T2-weighted MRI using driven equilibrium pulse. [Material and methods]Thirty-three men and 27 women aged 8–85 years old with sensory hearing loss or vertigo, and/or tinnitus were evaluated by thin-slice (0.75 mm) T2-weighted MRI. Five subjects (3 men, 2 women) without any auditory symptoms were also examined. [Results]Thin-slice T2WI drive MRI revealed several variations of the AICA/PICA coursing, such as a loop formation (n=30, 48 sides) or the IAC extension (n=19, 30 sides). Contact with the vestibulocochlear nerve was seen in 31.7% subjects (n=19, 27 sides). The AICA/PICA branching and shape patterns relative to the CPA and IAC were classified into four major types: type 1A, nonloop AICA/PICA in the CPA cistern; type 1 B, nonloop AICA/PICA (internal auditory artery) entering the IAC; type 2A, loop-type AICA/PICA in the CPA cistern; and type 2B, loop-type AICA/PICA entering the IAC. [Conclusion]There was statistically significant association between types 1A and 2A (P<.01) regarding the existence of any auditory 3 symptoms. The results of our study suggest that this classification is simple and very useful for the elucidation of the mechanism of auditory symptoms and deciding the therapeutic strategies.

[Objectives]The sensitivity of the current 10 mm cut-off diameter that is used to diagnose lymph node (LN) metastasis is too low. This is the first study to develop a new criterion to diagnose LN metastasis in a region-by-region manner using multi-detector computed tomography (MDCT). [Methods]1) The short-axis diameter of the LNs in MDCT images from 1-mm slices obtained immediately prior to surgery was compared with the pathological diagnosis in 78 uterine cervical cancer patients undergoing primary surgery. For the region-by-region analysis, we divided para-aortic and pelvic spaces into 13 regions. 2) In 28 cases in which patients received neoadjuvant chemotherapy (NAC) followed by surgery, we compared MDCT images before and after NAC. [Results]1) The optimal cut-off in the region-by-region analysis was 5 mm, yielding 71% sensitivity and 79% specificity. 2) NAC significantly decreased LN size (p < 0.0001). NAC decreased the number of swollen LN regions (> 5 mm) from 51% (81/158) to 26% (41/158). [Conclusions]The new criterion developed using MDCT could be effective for accurately assessing LN status. It also facilitates the assessment of NAC efficacy regarding the eradication of LN metastases.

[Purpose] "Misty mesentery" is a CT appearance of mesenteric fat changes with increased attenuation often existing with swelled mesenteric lymph nodes. We evaluated diagnostic performance of FDG-PET/CT in distinguishing viable malignant disorders from benign conditions in misty mesentery. [Materials and methods] 4236 FDG-PET/CT images were reviewed to identify patients with appearances of misty mesentery. Only the initial examinations were evaluated. Patients undergoing chemotherapy and/or radiotherapy within 3 months, patients with bulky mesenteric mass, and patients without follow-up examinations were excluded. Maximum short-axis diameter of mesenteric nodules (Diam-max) and maximum standardized uptake value (SUVmax) for mesenteric abnormalities were measured, and the diagnostic performance to differentiate between viable malignancy and stable lesions was assessed by receiver-operating characteristic (ROC) analysis, based on final diagnoses obtained by histology or follow-up examinations. Their significance was assessed by multivariate logistic regression. [Results] 71 studies met the inclusion criteria with confirmed diagnoses (13 viable malignancies; 58 stable lesions). Of the 13 malignant cases, 12 were lymphoma. ROC curves indicated an optimal Diam-max cut-off value of >10 mm and SUVmax cut-off of ≥3.0, with area under the curve of 0.961 and 0.926, respectively. Using the optimal Diam-max cut-off, sensitivity and specificity were 69% and 98%, respectively. Using the optimal SUVmax cut-off, they were 85% and 98%, respectively. The combination of either Diam-max > 10 mm or SUVmax ≥ 3.0 had a sensitivity of 92%. Both Diam-max and SUVmax were significant independent factors for predicting malignancy. [Conclusions] FDG-PET/CT is feasible for identifying viable malignancy in misty mesentery.

[Objective]: To investigate whether proton density-weighted imaging can detect the "hot cross bun" sign in the pons in multiple system atrophy with predominant cerebellar ataxia significantly better than T2-weighted imaging at 3T. [Methods]: Sixteen consecutive patients with multiple system atrophy with predominant cerebellar ataxia according to the Consensus Criteria were reviewed. Axial unenhanced proton density-weighted imaging and T2-weighted imaging were obtained using a dual-echo fast spin-echo sequence at 3T. Two neuroradiologists independently evaluated visualisation of the abnormal pontine signal using a 4-point visual grade from Grade 0 (no "hot cross bun" sign) to Grade 3 (prominent "hot cross bun" sign on two or more sequential slices). Differences in grade between proton density-weighted imaging and T2-weighted imaging were statistically analysed using the Wilcoxon signed-rank test. [Results]: In 11 patients (69%), a higher grade was given for proton density-weighted imaging than T2-weighted imaging. In 1 patient (6%), grades were the same (Grade 3) on both images. In the remaining 4 patients (25%), signal abnormalities were not detected on either image (Grade 0). The "hot cross bun" sign was thus observed significantly better on proton density-weighted imaging than on T2-weighted imaging (P = 0.001). [Conclusions]: The "hot cross bun" sign considered diagnostic for multiple system atrophy with predominant cerebellar ataxia is significantly better visualised on proton density-weighted imaging than on T2-weighted imaging at 3T.

IgG4-related systemic disease (IgG4-RSD) is an emerging clinical entity about which much remains to be elucidated, in terms of its aetiology, pathogenesis, diagnosis, treatment and outcome. Autoimmune pancreatitis (AIP) and Mikulicz disease (MD) are the two major, well-studied constituents of IgG4-RSD. AIP and MD have common characteristics of forming tumour-mimicking lesions that consist of lymphoplasmacytic infiltrates and fibrosclerosis with numerous immunoglobulin G4 (IgG4)-positive plasma cells, as well as various multi-organ manifestations of IgG4-RSD. 2-[(18)F]-fluoro-2-deoxy-d-glucose positron-emission tomography/ computed tomography (FDG PET/CT) enables the acquisition of whole-body images and provides functional information about disease activity; as such it has a valuable role in staging extent of disease, guiding biopsy, and monitoring response to treatment. However, FDG PET/CT is likely to be only one component of the management strategy, and clinical, laboratory, imaging and histological findings are crucial in the overall diagnosis of the condition. At present FDG PET/CT does not have a well-established role in the assessment of patients with IgG4-RSD and future prospective studies are required to define the cost-effectiveness and clinical impact in this patient group more accurately.

[Objectives]To detect symptomatic hemispheres during the postoperative course of subarachnoid haemorrhage (SAH) using arterial spin labelling (ASL). [Methods]Eighteen patients with aneurysmal SAH were included; four exhibited symptomatic vasospasm postoperatively. All patients underwent ASL on days 9–10 (single time-point ASL). Nine patients underwent serial measurements of ASL (serial ASL) on days 1–2, 9–10 and 13–21, and seven patients also underwent imaging on days 4–7. CBF in the posterior part of the MCA territory was measured, and the ipsilateral/contralateral ratio of CBF was calculated. Differences between symptomatic hemispheres and others underwent ROC analysis. [Results]Single time-point ASL revealed that CBF_{day9-10} and CBF_{i/c_day9-10} were significantly lower in symptomatic hemispheres than in asymptomatic hemispheres (P < 0.001). Serial ASL was significantly decreased on CBF_{day4-7} compared with CBF_{day1-2} and on CBF_{day9-10} compared with CBF}_{day4-7}, and significantly increased on CBF_{day13-21} compared with CBF_{day9-10}. ROC analysis of single time-point ASL revealed that AUC for CBF_{day9-10} was 0.95, significantly higher than CBF_{i/c_day9-10} (P < 0.001). ROC analysis of serial ASL showed that AUC for CBF_{day9-10} was 0.93 and significantly higher than CBF_{day9-10/day1-2} and CBF_{i/c_day9-10} (P < 0.001). [Conclusions]Single time-point ASL revealed significant CBF reduction in symptomatic hemispheres compared with asymptomatic hemispheres. Serial ASL showed time-dependent CBF changes after SAH.

[Purpose]: The usefulness of 18F fluorodeoxyglucose (FDG) positron emission tomography (PET) in pediatric Hodgkin lymphoma (p-HL) has been well demonstrated; however, pediatric non-Hodgkin lymphoma (p-NHL) has distinct characteristics from p-HL and adult NHL. We assessed roles of FDG PET in p-NHL. [Materials and Methods]: Nineteen patients with p-NHL underwent 80 scans. Scans for staging (group A, n = 6) and response assessment (group B, n = 42) were compared with conventional imaging modalities (CIMs). Scans within group B for end-chemotherapy assessment (subgroup B+, n = 11) and for post-therapeutic surveillance (group C, n = 32) were analyzed for diagnostic performance. [Results]: In group A, PET and CIM demonstrated comparable results. In group B, PET diagnoses were concordant with CIM in 21 and discordant in 11 studies. Of the discordant cases, PET suggested remnant lesions in 5 cases, whereas CIM suggested lesions in 6 cases. PET modified therapeutic strategy in 4 cases by detecting new extranodal lesions. In subgroup B+, sensitivity, specificity, and accuracy for predicting relapse were 50%, 71%, and 64%, respectively. In group C, sensitivity, specificity, and accuracy were 100%, 87%, and 88%, respectively, but positive predictive value was 33%. [Conclusions]: The role of FDG PET in p-NHL may be limited, unlike with p-HL or adult NHL. Nevertheless, FDG PET may serve complementarily in detecting unexpected lesions that can emerge in p-NHL.

OBJECTIVES: To reveal the characteristics of susceptibility‐weighted imaging (SWI) under low cerebral blood flow (CBF) induced by hyperventilation (HV). MATERIALS AND METHODS: This study was approved by the institutional review board. Informed consent was obtained. Six healthy volunteers (5 men, 1 woman; mean age, 29 years; range, 24‐33 years) underwent SWI and arterial spin labeling perfusion imaging under normal ventilation (NV) and HV at 3.0 T. Regions of interest (ROIs) were placed on gray matter (GM) and white matter (WM) of the frontal lobe (FL) and occipital lobe (OL). Intensities of ROIs were compared between NV and HV. Contrast of veins compared with adjacent cerebral parenchyma (CV) was also compared between NV and HV. RESULTS: CBF during HV (CBFHV) was decreased compared with CBF during NV (CBFNV) (29.1 ± 4.6%). FL‐GMHV and OL‐GMHV showed significant signal decreases compared with FL‐GMNV and OL‐GMNV, respectively (P= .018, .017). CVHV was significantly increased compared with CVNV (164.1 ± 29.9%) (P= .00019). CONCLUSIONS: SWI sensitively reflects HV‐induced decreases in CBF. The present results might assist in the interpretation of SWI in clinical practice, since CBF decreases might also influence signal changes on SWI.

BACKGROUND AND PURPOSE: The purpose was to characterize (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) findings after stereotactic body radiation therapy (SBRT) for lung cancer. MATERIALS AND METHODS: This was a retrospective review of 32 FDG-PET scans from 23 patients who underwent SBRT for lung cancer and who showed no evidence of local recurrence. The FDG uptake by lesions was assessed visually using a 3-point scale (0, none or faint; 1, mild; or 2, moderate to intense), and the demarcation (ill- or well-defined) was evaluated. For semi-quantitative analysis, the maximum standardized uptake value (SUVmax) was calculated. RESULTS: Grade 2 intensity was observed in 70%, 33%, 30%, and 0% of PET scans performed <6, 6-12, 12-24, and >24 months, respectively, after SBRT; well-defined demarcation was observed in 80%, 33%, 40%, and 17%, respectively, and the respective means of the SUVmax were 4.9, 2.6, 3.0, and 2.3. The SUVmax was significantly higher for scans performed at <6 months than at 6-12 or >24 months. CONCLUSIONS: FDG uptake tended to be intense and well-defined at early times after SBRT, especially within 6 months, and was faint and ill-defined at later periods. Moderate to intense FDG uptake observed soon after SBRT does not always indicate a residual tumour.

Discrepancies exist in the literature regarding contrast between gray and white matter on spin-echo (SE) T1-weighted MR imaging at 3 T. The present study quantitatively assessed differences in gray matter-white matter contrast on both single- and multi-slice SE T1-weighted imaging between 3 and 1.5 T. SE T1-weighted sequences with the same parameters at both 3 and 1.5 T were used. Contrast-to-noise ratio (CNR) between gray and white matter (CNR(GM-WM)) was evaluated for both frontal lobes. To assess the effects of interslice gap, multi-slice images were obtained with both 0 and 25% interslice gap. Single-slice CNR(GM-WM) was higher at 3 T (17.66 +/- 2.68) than at 1.5 T (13.09 +/- 2.35; P < 0.001). No significant difference in CNR(GM-WM) of multi-slice images with 0% gap was noted between 3 and 1.5 T (3T, 8.61 +/- 2.55; 1.5T, 7.43 +/- 1.20; P > 0.05). Multi-slice CNR(GM-WM) with 25% gap was higher at 3T (12.47 +/- 3.31) than at 1.5 T (9.73 +/- 1.37; P < 0.001). CNR(GM-WM) reduction rate of multi-slice images with 0% gap compared with single-slice images was higher at 3T (0.47 +/- 0.13) than at 1.5 T (0.38 +/- 0.09; P = 0.02). CNR(GM-WM) on single-slice SE T1-weighted imaging and CNR(GM-WM) on multi-slice images with 25% interslice gap were better at 3 T than at 1.5 T. The influence of multi-slice imaging on CNR(GM-WM) was significantly larger at 3T than at 1.5 T.

Purpose: To prospectively compare 3.0- and 1.5-T three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography in patients with moyamoya disease, with special emphasis on the visualization of abnormal netlike vessels (moyamoya vessels). Materials and Methods: Study protocols were approved by the local ethics committee; written informed consent was obtained from all patients. The study included 24 consecutive patients with moyamoya disease (four male and 20 female patients). Patients ranged in age from 17 to 66 years (mean age, 41 years). Moyamoya disease had been diagnosed in all patients before they were entered into the study. All patients underwent 3D TOF MR angiography at both 3.0 and 1.5 T; imaging examinations were performed within 14 days of each other. Maximum intensity projections (MIPs) obtained with MR angiography performed at both 3.0 and 1.5 T were evaluated by two neuroradiologists; the visualization of moyamoya vessels was graded according to a 4-point scale. For both 3.0- and 1.5-T imaging, the number of high-signal-intensity areas and the summation of cross-sectional areas of high signal intensity on source images obtained at the same level of MR angiography were compared quantitatively by using the Wilcoxon matched-pair signed-rank test. Results: Moyamoya vessels were better visualized on MIPs obtained with 3.0-T imaging than on MIPs obtained with 1.5-T imaging (P < .001). At the identical level of the source image, 3.0-T imaging depicted more high-signal-intensity areas than did 1.5-T imaging. Wider cross-sectional areas of moyamoya vessels were visualized with 3.0-T imaging than with 1.5-T imaging (P < .001). Conclusion: Moyamoya vessels are better depicted with MR angiography at 3.0 T than at 1.5 T.