Search

A 23-year-old man with a history of migraine and focal seizures, developed painless visual loss in the left eye associated with optic disk edema. There was no recent history of cat exposure except for a cat that lives outside. Initial laboratory studies were negative. magnetic resonance imaging brain and orbits without and with fat suppression and intravenous contrast was normal. The patient admitted to routinely skinning, processing and consuming deer while not wearing gloves, and he also frequently had cuts on his hands while doing so. The serum Toxoplasma gondii IgG antibody returned at400 (0-7.1 IU/mL) with the IgM at 10.4 (0-7.9 AU/mL).

PURPOSE: Spectrally selective fat saturation (FatSat) sequence is commonly used to suppress signal from adipose tissue. Conventional SINC-shaped pulses are sensitive to B(0) off-resonance and B(1)(+) offset. Uniform fat saturation with large spatial coverage is especially challenging for the body and breast MRI. The aim of this study is to develop spectrally selective FatSat pulses that offer more immunity to B(0)/B(1)(+) field inhomogeneities than SINC pulses and evaluate them in bilateral breast imaging at 3T. MATERIALS AND METHODS: Optimized composite pulses (OCP) were designed based on the optimal control theory with robustness to a targeted B(0)/ B(1)(+) conditions. OCP pulses also allows flexible flip angles to meet different requirements. Comparisons with the vendor-provided SINC pulses were conducted by numerical simulation and in vivo scans using a 3D T(1)-weighted (T(1)w) gradient-echo (GRE) sequence with coverage of the whole-breast. RESULTS: Simulation revealed that OCP pulses yielded almost half of the transition band and much less sensitivity to B(1)(+) inhomogeneity compared to SINC pulses with B(0) off-resonance within ±200 Hz and B(1)(+) scale error within ±0.3 (P

Imaging studies of peripheral nerves have increased considerably in the last ten years. In addition to the classical and still valid study by ultrasound, new neurographic techniques developed from conventional morphological sequences (including 3D isotropic studies with fat suppression) are making it possible to assess different peripheral nerves and plexuses, including small sensory and/or motor branches, with great precision. Diffusion-weighted sequences and diffusion tensor imaging have opened a new horizon in neurographic studies. This new approach provides morphological and functional information about the internal structure and pathophysiology of the peripheral nerves and diseases that involve them. This update reviews the different MR neurography techniques available for the study of the peripheral nerves, with special emphasis on new sequences based on diffusion.

Purpose To investigate the potential of ESWAN in differentiating borderline epithelial ovarian tumors (BEOTs) from malignant epithelial ovarian tumors (MEOTs). Method Thirty-four patients with 37 lesions were enrolled, including 14 BEOTs and 23 MEOTs. The magnitude, phase, R2* and T2* maps were analyzed by two observers. The regions of interest were drawn along the boundaries of tumors on the slice with maximal solid area, according to fat suppression T2WI and T1WI. The consistency among the three measurements taken by two observers was tested by intra-class correlation coefficients. Agreement of average values measured by two observers was evaluated by Bland-Altman plots. All the data of BEOTs and MEOTs were compared using the independent-sample t test. The receiver operating characteristic curve was used to evaluate the diagnostic performance. Results No statistical differences were observed in the magnitude and phase values between two tumor groups. The R2* value of BEOTs was lower than that of MEOTs (P Conclusions R2* and T2* values can be used for quantificationally differentiating BEOTs from MEOTs and the R2* has better diagnostic performance.

Magnetic resonance imaging has become a fundamental tool for the evaluation of head and neck tumors. The anatomic details that magnetic resonance images provide are fundamental for diagnosing, characterizing, and staging both primary tumors and lymph node metastases. In addition to technical improvements in anatomic sequences, such as Dixon techniques to improve fat suppression, other sequences being developed, such as diffusion and perfusion, provide molecular, biological, and physiological information about the tumor and are yielding imaging biomarkers that can help in determining the tumor's biology at the time of diagnosis and in the follow-up of the disease. Magnetic resonance imaging also provides very useful information about the response to treatment.

Introduction The determination of the precise location of unruptured paraclinoid aneurysms with respect to the dura is essential in order to establish the risk of subarachnoid hemorrhage (SAH). In equivocal cases, current imaging modalities are often limited when trying to distinguish the precise relationship of these aneurysms with respect to the dura. We assessed the utility of vessel wall magnetic resonance (VW-MR) imaging in identifying the definitive location of unruptured paraclinoid aneurysms. Methods We performed an observational retrospective review using a prospective database of patients undergoing 3T VW-MR of the brain. We included patients that underwent VW-MR gadolinium-enhanced T1-weighted black-blood sequences with fat suppression and saturation band to evaluate unruptured paraclinoid region aneurysms. The dural locations of the aneurysms were first identified on DSA or TOF-MRA and subsequently with VW-MR. The location of aneurysms on VW-MR were then compared qualitatively with the reference standard DSA/TOF-MRA by 2 neurovascular imaging experts. Results Fifteen patients with unruptured paraclinoid region aneurysms were imaged with VW-MR. The extradural or intradural locations of the aneurysms were determined in 80% of patients using VW-MR compared to 47% with DSA/MRA. Conclusions VW-MRI may be a feasible imaging technique for identifying the extradural or intradural location of unruptured paraclinoid aneurysms and may help guide management. Further larger studies may be warranted.

To avoid artifacts and interpretation mistakes, improvements in the uniformity of magnetic resonance imaging (MRI) is very important. The aim of this study is to develop a bias field-based uniformity correction algorithm and to confirm the feasibility of its application with an integrated positron emission tomography (PET)/MRI system using standard MRI pulse sequences (T2-weighted, half-Fourier, single-shot turbo spin echo, T2-weighted turbo spin echo with fat suppression, and three-dimensional, volumetric, T1-weighted gradient recalled echo interpolated breath-hold examination using controlled aliasing in parallel imaging that results in increased acceleration). We used phantoms containing NaCl and NaCl + NiSO4 solutions, and considered the percent image uniformity (PIU) as the evaluation parameter. The elicited PIU results using the correction algorithm were distinct for all sequences and phantoms. The results of this study suggested that the bias field-based algorithm allows uniformity improvements in MRI in terms of PIU.

Rationale and Objectives The aim of this study was to reveal the distinctive features of magnetic resonance imaging (MRI) for distinguishing brucellar spondylodiscitis (BSD) from tuberculous spondylodiscitis (TSD) in the acute and subacute stages. Methods This study involved 14 patients with BSD and 18 patients with TSD from May 2011 to January 2015. BSD was diagnosed based on ≥1/160 titers of a Brucella agglutination test or isolation of Brucella spp. TSD was diagnosed based on the isolation of tuberculosis bacteria. All patients underwent T1- and T2-weight imaging (T1WI and T2WI) and fat suppression T2WI (FS T2WI). The height and the signal intensity (SI) of the vertebra and intervertebral disc were assessed. The distinctive MRI features were compared using the chi-square test. The SI of the vertebra between BSD and TSD was observed in terms of histogram characteristics of kurtosis, skewness, and percentile (75%–25%) on FS T2WI. Results Twenty-nine (76.3%) vertebrae of BSD were infected throughout the whole vertebra, and 49 (90.7%) vertebrae of TSD were infected near the osseous end plate (P Conclusions The nearly intact vertebra with homogeneous high signal on FS T2WI was an important MRI feature for distinguishing BSD from TSD in the acute and subacute stages.

Purpose To suppress olefinic signals and enable simultaneous and quantitative estimation of multiple functional parameters associated with water and lipid, we investigated a modified method using chemical shift displacement and recovery-based separation of lipid tissue (SPLIT) involving acquisitions with different inversion times (TIs), echo times (TEs), and b-values. Materials and methods Single-shot diffusion echo-planar imaging (SSD-EPI) with multiple b-values (0–3000 s/mm2) was performed without fat suppression to separate water and lipid images using the chemical shift displacement of lipid signals in the phase-encoding direction. An inversion pulse (TI = 292 ms) was applied to SSD-EPI to remove olefinic signals. Consecutively, SSD-EPI (b = 0 s/mm2) was performed with TI = 0 ms and TE = 31.8 ms for T1 and T2 measurements, respectively. Under these conditions, transverse water and lipid images at the maximum diameter of the right calf were obtained in six healthy subjects. T1, T2, and the apparent diffusion coefficients (ADC) were then calculated for the tibialis anterior (TA), gastrocnemius (GM), and soleus (SL) muscles, tibialis bone marrow (TB), and subcutaneous fat (SF). Perfusion-related (D*) and restricted diffusion coefficients (D) were calculated for the muscles. Lastly, the lipid fractions (LF) of the muscles were determined after T1 and T2 corrections. Results The modified SPLIT method facilitated sufficient separation of water and lipid images of the calf, and the inversion pulse with TI of 292 ms effectively suppressed olefinic signals. All quantitative parameters obtained with the modified SPLIT method were found to be in general agreement with those previously reported in the literature. Conclusion The modified SPLIT technique enabled sufficient suppression of olefinic signals and simultaneous acquisition of quantitative parameters including diffusion, perfusion, T1 and T2 relaxation times, and LF.

Objective FSE sequences play key roles in neck MRI despite the susceptibility issues in neck region. Iterative decomposition of asymmetric echoes (IDEAL, GE) is a promising method that separates fat and water images resulting in high SNR and improved fat suppression. We tested how neck tissue contrasts, image artifacts and fat separation as opposed to fat suppression in terms of image quality compare between routine and IDEAL FSE. Methods IDEAL based and routine T1 and T2-weighted FSE sequences were applied for neck MRI at 1.5T and 3T. Overall image quality including fat suppression, tissue contrast, image artifacts and lesion conspicuity were subjectively assessed for 20 patients clinically indicated for neck MRI. Quantitative tissue contrast estimates from parotid area were compared between IDEAL and routine FSE for 7 patients. Four patients with oncocytoma were also reviewed to assess benefits of separately reconstructed fat specific image sets. Results Subjective tissue contrast and overall image quality including image sharpness, fat suppression and image artifacts were superior for IDEAL sequences. For oncocytoma fat specific IDEAL images provided additional information. Objective CNR estimates from a central slice were equivalent for IDEAL and routine FSE at both field strengths. Conclusions We demonstrated that high SNR inherent in IDEAL FSE consistently translates into high tissue contrast with image quality advantages in neck anatomy where large susceptibility variation and physiological motions reduce image quality for conventional FSE T1 and T2. However, the objective contrast estimates for parotid gland at isocenter were statistically equivalent for IDEAL and conventional FSE perhaps because at or near isocenter routine FSE works well. Additionally, fat specific IDEAL image sets add to diagnostic specificity for fat deficient lesions.

Fat suppression technique is a valuable resource in musculoskeletal magnetic resonance (MR) imaging that is helpful in the diagnosis and differentiation of various pathologies. Multiple different techniques are available for fat suppression, including frequency selective pulse sequence, inversion recovery, hybrid technique, chemical shift imaging (CSI) and the related Dixon based approach. The utility of CSI and Dixon approach is not well recognized in the domain of musculoskeletal MR imaging. The aim of this article is to review the various options for fat suppression and present focused discussion of the role of CSI and Dixon techniques for musculoskeletal MR imaging.

Liver MR is a well-established modality with multiparametric capabilities. However, to take advantage of its full capacity, it is mandatory to master the technique and optimize imaging protocols, apply advanced imaging concepts and understand the use of different contrast media. Physiologic artefacts although inherent to upper abdominal studies can be minimized using triggering techniques and new strategies for motion control. For standardization, the liver MR protocol should include motion-resistant T2-w sequences, in-op phase GRE T1 and T2-w fast spin echo sequences with fat suppression. Diffusion-weighted imaging (DWI) is mandatory, especially for detection of sub-centimetre metastases. Contrast-enhanced MR is the cornerstone of liver MR, especially for lesion characterization. Although extracellular agents are the most extensively used contrast agents, hepatobiliary contrast media can provide an extra-layer of functional diagnostic information adding to the diagnostic value of liver MR. The use of high field strength (3T) increases SNR but is more challenging especially concerning artefact control. Quantitative MR belongs to the new and evolving field of radiomics where the use of emerging biomarkers such as perfusion or DWI can derive new information regarding disease detection, prognostication and evaluation of tumour response. This information can overcome some of the limitations of current tests, especially when using vascular disruptive agents for oncologic treatment assessment. MR is, today, a robust, mature, multiparametric imaging modality where clinical applications have greatly expanded from morphology to advanced imaging. This new concept should be acknowledged by all those involved in producing high quality, high-end liver MR studies. info:eu-repo/semantics/publishedVersion

Purpose To introduce a simple analytical formula for estimating T 2 from a single Double-Echo in Steady-State (DESS) scan. Methods Extended Phase Graph (EPG) modeling was used to develop a straightforward linear approximation of the relationship between the two DESS signals, enabling accurate T 2 estimation from one DESS scan. Simulations were performed to demonstrate cancellation of different echo pathways to validate this simple model. The resulting analytic formula was compared to previous methods for T 2 estimation using DESS and fast spin-echo scans in agar phantoms and knee cartilage in three volunteers and three patients. The DESS approach allows 3D (256 × 256 × 44) T 2 -mapping with fat suppression in scan times of 3–4 min. Results The simulations demonstrated that the model approximates the true signal very well. If the T 1 is within 20% of the assumed T 1 , the T 2 estimation error was shown to be less than 5% for typical scans. The inherent residual error in the model was demonstrated to be small both due to signal decay and opposing signal contributions. The estimated T 2 from the linear relationship agrees well with reference scans, both for the phantoms and in vivo. The method resulted in less underestimation of T 2 than previous single-scan approaches, with processing times 60 times faster than using a numerical fit. Conclusion A simplified relationship between the two DESS signals allows for rapid 3D T 2 quantification with DESS that is accurate, yet also simple. The simplicity of the method allows for immediate T 2 estimation in cartilage during the MRI examination.

A radiofrequency (RF) pulse-based MRI method is introduced as a novel fat (or water) segmentation method that, unlike the mostly used Dixon's method, does not depend on the echo times. A pair of rectangular RF pulses of opposite direction, when the duration of its rectangular pulse and the off-resonance of its carrier frequency are set to specific values, is proposed as a preparatory RF pulse to be used for the quantitative fat segmentation. The optimal duration of its rectangular pulse and its specific off-resonance were first determined theoretically. Then, such pair of rectangular pulses of opposite direction (PROD pulse) was applied in imaging a few phantoms and volunteers. During the imaging experiments, MRI images were dynamically acquired with the PROD pulse while its carrier frequency was varied in a predefined off-resonance range. By analyzing the dynamically acquired signal changes, the theoretical properties of the PROD pulse were confirmed and the utility of the PROD pulse for the fat segmentation was verified. All MRI scans were performed in a clinical 3T system. The PROD pulse, if the duration of each rectangular pulse was set to 1.66ms and its carrier frequency was set to a specific off-resonance (e.g. ±223.5Hz, or -670.5Hz) in 3T, was effective in optimally modulating MRI signals to be used for the fat-water segmentation. Therefore, the PROD pulse can successfully be used as a preparatory RF pulse in MRI to achieve effective fat (or water) segmentation in MRI.

To assess the value of section-selection gradient reversal (SSGR) in liver diffusion-weighted imaging (DWI) by comparing it to conventional DWI with an emphasis on chemical shift artefacts and lesion conspicuity.Forty-eight patients (29 men and 19 women; age range 33-80 years) with 48 liver lesions underwent two DWI examinations using spectral presaturation with inversion recovery fat suppression with and without SSGR at 3 T. Two reviewers evaluated each DWI (b = 100 and b = 800 image) with respect to chemical shift artefacts and liver lesion conspicuity using five-point scales and performed pairwise comparisons between the two DWIs. The signal-to-noise ratio (SNR) of the liver and the lesion and the lesion-liver contrast-to-noise ratio (CNR) were also calculated.SSGR-DWI was significantly better than conventional DWI with respect to chemical shift artefacts and lesion conspicuity in both separate reviews and pairwise comparisons (p0.05). There were significant differences in the SNR of the liver (b = 100 and b = 800 images) and lesion (b = 800) between SSGR-DWI and conventional DWI (p0.05).Applying the SSGR method to DWI using SPIR fat suppression at 3 T could significantly reduce chemical shift artefacts without incurring additional acquisition time or SNR penalties, which leads to increased conspicuity of focal liver lesions.

Purpose To compare intraindividually the nerve conspicuity of the brachial and lumbosacral plexus on diffusion-weighted (DW) MR neurography (MRN) at two different field strengths. Materials and methods 16 healthy volunteers were investigated at 3.0T and 1.5T applying optimized variants of a DW spin-echo echo-planar imaging sequence with short TI inversion recovery fat suppression. Full-volume (FV) and curved sub-volume (CSV) maximum intensity projection (MIP) images were reconstructed and nerve conspicuity was visually assessed. Moreover, visible length and sharpness of the nerves were quantitatively analyzed. Results On FV MIP images, nerve conspicuity at 3.0T compared to 1.5T was worse for brachial plexus ( P =0.00228), but better for lumbosacral plexus ( P =0.00666). On CSV MIP images, nerve conspicuity did not differ significantly for brachial plexus, but was better at 3.0T for lumbosacral plexus ( P =0.00091). The visible length of the analyzed nerves did not differ significantly with the exception of some lumbosacral nerves, which were significantly longer at 3.0T. The sharpness of all investigated nerves was significantly higher at 3.0T by about 40–60% for cervical and 97–169% for lumbosacral nerves. Conclusion DW MRN imaging at 3.0T compared to 1.5T is superior for lumbosacral plexus, but not for brachial plexus.

Aim To evaluate two fat-suppression techniques: short tau inversion recovery (STIR) and spectral adiabatic inversion recovery (SPAIR) regarding image quality and diagnostic performance in diffusion-weighted imaging (DWI) of breast lesions at 3 T. Materials and methods Ninety-two women (mean age 48 ± 12.1 years; range 21–78 years) underwent breast MRI. Two DWI pulse sequences, with b-values (50 and 1000 s/mm 2 ) were performed with STIR and SPAIR. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), suppression homogeneity, and apparent diffusion coefficient (ADC) values were quantitatively assessed for each technique. Values were compared between techniques and lesion type. Receiver operating characteristics (ROC) analysis was used to evaluate lesion discrimination. Results One hundred and fourteen lesions were analysed (40 benign and 74 malignant). SNR and CNR were significantly higher for DWI-SPAIR; fat-suppression uniformity was better for DWI-STIR ( p −4 ). ADC values for benign and malignant lesions and normal tissue were 1.92 × 10 −3 , 1.18 × 10 −3 , 1.86 × 10 −3 s/mm 2 for DWI-STIR and 1.80 × 10 −3 , 1.11 × 10 −3 , 1.79 × 10 −3 s/mm 2 for SPAIR, respectively. Comparison between fat-suppression techniques showed significant differences in mean ADC values for benign ( p = 0.013) and malignant lesions ( p = 0.001). DWI-STIR and -SPAIR ADC cut-offs were 1.42 × 10 −3 and 1.46 × 10 −3 s/mm 2 , respectively. Diagnostic performance for DWI-STIR versus SPAIR was: accuracy (81.6 versus 83.3%), area under curve (87.7 versus 89.2%), sensitivity (79.7 versus 85.1%), and specificity (85 versus 80%). Positive predictive value was similar. Conclusion The fat-saturation technique used in the present study may influence image quality and ADC quantification. Nevertheless, STIR and SPAIR techniques showed similar diagnostic performances, and therefore, both are suitable for use in clinical practice.

To compare diffusion weighted imaging with background suppression (DWIBS) sequence with classic spectral diffusion sequence (DWI) with and without respiratory gating in mediastinal lymph node analysis at 3T.26 patients scheduled for mediastinoscopic lymph node analysis, prospectively undergone a thoracic 3T MRI with DWIBS (FatSat=STIR; TR/TE=6674.1/44.7ms; IR=260 ms) and DWI sequences (FatSat=SPIR; TR/TE=1291/59.6 ms) (b=0-400-800 s/mm2) with and without (free breathing) respiratory gating. Images at b=800 were analyzed by two radiologists. They performed qualitative analysis of fat-sat homogeneity and motion artifacts, rated from 0 to 4, and quantitative evaluation by studying signal to background (STB) of lymph nodes.Quality of fat suppression was significantly higher for DWIBS than for DWI both for free-breathing (score 3.48±0.65 vs. 1.76±0.96, p0.0001) and respiratory-gated scans (3.17±0.77 vs. 1.72±0.73, p=0.0001). Similarly, artifacts were reduced with DWIBS (3.16±0.47 vs. 1.76±0.59, p0.0001; 3.0±0.73 vs. 2.04±0.53, p=0.0001). Quantitative analysis showed higher STB with DWIBS (3.26±1.83 vs. 0.98±0.44, p0.0001; 3.56±, 2.09 vs. 0.92±0.59, p0.0001). Gating did not improve image quality and STB on DWIBS (p0.05).In thoracic MRI, ungated DWIBS sequence improves fat-sat homogeneity, reduces motion artifacts and increases STB of lymph nodes. Respiratory gating does not improve DWIBS image quality.

To compare a fast 3D VIBE sequence with Dixon fat saturation and CAIPIRINHA acceleration techniques (3D VIBE(CAIPI-DIXON)) to a standard 2D FLASH sequence with spectral fat saturation and conventional GRAPPA acceleration technique (2D Flash(GRAPPA-fs)) for non-enhanced imaging of the pancreas.In this retrospective, institutional review board-approved intra-individual comparison study, 29 patients (7 female, 22 male; mean age 60.4 ± 20.9 years) examined on a 48-channel 3.0-T MR system (MAGNETOM Skyra VD 13, Siemens Healthcare Sector, Germany) were included. 3D VIBE(CAIPI-DIXON) (TR/TE-3.95/2.5+1.27 ms; spatial resolution-1.2 × 1.2 × 3.0 mm(3); CAIPIRINHA 2 × 2 [1], acquisition time-0:12 min) and 2D Flash(GRAPPA-fs) (TR/TE-195/3.69 ms; 1.2 × 1.2 × 3.0 mm(3); GRAPPA 2, 3 × 0:21 min) sequences were performed in each subject in random order prior to the administration of an intravenous contrast agent. Two radiologists evaluated the images with regard to diagnostic preference. Semi-quantitative signal ratios were calculated for the pancreas versus the liver, spleen, muscle, and visceral fat. Inter-reader agreement was calculated using unweighted Cohen's kappa. Signal ratio results were analyzed using a univariate analysis of variance. Additional signal-to-noise (SNR) measurements were performed in a phantom.3D VIBE(CAIPI-DIXON) was preferred in 72.4% (both readers) and 2D Flash(GRAPPA-fs) in 3.4%/6.9% (reader 1/2) of cases with a kappa value of 0.756. The main reasons for this preference were homogenous fat saturation with 3D VIBE(CAIPI-DIXON) and reduced motion artifacts due to a faster acquisition, leading to improved delineation of the pancreas. Signal ratios of pancreatic to fat signal for 3D VIBE(CAIPI-DIXON) (10.08 ± 3.48) and 2D Flash(GRAPPA-fs) (6.53 ± 3.07) were statistically different (P.001). However, no additional statistically significant differences in signal ratios were identified (range: 0.73 ± 0.18 to 1.37 ± 0.40; .514P.961). SNR did not statistically significantly differ between the sequences.3D VIBE(CAIPI-DIXON) enables robust pancreatic imaging with a shorter time and improved fat suppression relative to conventional 2D Flash(GRAPPA-fs). At an acquisition time of 12 seconds, 3D VIBE(CAIPI-DIXON) can be obtained in considerably less time than standard fat-saturated VIBE sequences.

Purpose The purpose of this study was to discuss the usefulness of magnetic resonance imaging in evaluating perianal fistulas, their ramifications, extent, associated abscesses and relations with the anal sphincter complex and its role in preoperative classification. Material & methods A retrospective study was carried out using picture archiving and communication system. Data of 58 patients presented with a clinical suspicious of perianal fistula from April 2012 to March 2013 was collected. In all patients pre contrast T2 propeller with and without fat suppression, diffusion weighted and pre and post contrast liver acceleration volume acquisition sequences were obtained. Pulse sequences were as follows: T2 propeller (TR: 7766 ms, TE: 122 ms), Diffusion weighted (TR: 7000 ms, TE: 67 ms), LAVA (TR: 7 ms, TE: 3.242 ms). Results MRI revealed a total number of 38 fistulae in 35 (60%) patients while 13 (22%) patients had only perianal sinuses. Out of these 35 patients, 4 were females and 31 were male subjects. Out of total 38 fistulae seen in these 35 patients, 11 (29%) were transsphincteric, 24 (63%) were intersphincteric and 2 (5%) were suprasphincteric. Only 1 (3%) case was extrasphincteric fistula. Twenty-six fistulae (68%) were simple, whereas 12 (32%) showed associated abscess formation, inflammation and branching course. Conclusion Our results support that MRI is the method of choice for evaluating perianal fistulae as they display the anatomy of the sphincter muscles orthogonally with a background of good contrast resolution. Moreover, with MRI we can accurately classify perianal fistulas preoperatively along with the detection of associated infection and help in planning a successful surgery.

Purpose The purpose of this study was to compare diagnostic capabilities for assessment of recurrence in non-small cell lung cancer (NSCLC) patients by contrast-enhanced whole-body MRI (CE-WB-MRI) with and without CE-Quick 3D and double RF fat suppression technique (DFS), FDG-PET/CT and conventional radiological examinations. Materials and methods A total of 134 pathologically proven and completely resected NSCLC patients (78 males, 56 females; mean age: 72 years) underwent FDG-PET/CT, CE-WB-MRI with and without Quick 3D and DFS at 3 T as well as conventional radiological examinations. The probability of recurrence was assessed with a 5-point scoring system on a per-patient basis, and final diagnosis was made by consensus between two readers. The capability for overall recurrence assessment by all the methods was compared by means of ROC analysis and their sensitivity, specificity and accuracy by means of McNemar's test. Results Although areas under the curve did not show any significant differences, specificity (100%) and accuracy (95.5%) of CE-WB-MRI with CE-Quick 3D and DFS were significantly higher than those of FDG-PET/CT (specificity: 93.6%, p = 0.02; accuracy: 89.6%, p = 0.01) and conventional radiological examinations (specificity: 92.7%, p = 0.01; accuracy: 91.0%, p = 0.03). In addition, specificity of CE-WB-MRI without CE-Quick 3D and DFS (100%) was significantly higher than that of FDG-PET/CT (p = 0.02) and conventional radiological examinations (p = 0.01). Conclusion Specificity and accuracy of CE-WB-MRI with CE-Quick 3D and DFS for assessment of recurrence in NSCLC patients are at least as high as, or higher than those of others.

The objective of this paper was to investigate the value of apparent diffusion coefficients (ADCs) for differential diagnosis among solid pancreatic masses using respiratory triggered diffusion-weighted MR imaging with inversion-recovery fat-suppression technique (RT-IR-DWI) at 3.0 T.20 normal volunteers and 72 patients (Pancreatic ductal adenocarcinoma [PDCA, n=30], mass-forming pancreatitis [MFP, n=15], solid pseudopapillary neoplasm [SPN, n=12], and pancreatic neuroendocrine tumor[PNET, n=15]) underwent RT-IR-DWI (b values: 0 and 600 s/mm(2)) at 3.0 T. Results were correlated with histopathologic data and follow-up imaging. ADC values among different types of pancreatic tissue were statistically analyzed and compared.Statistical difference was noticed in ADC values among normal pancreas, MFP, PDCA, SPN and PNET by ANOVA (p.001). Normal pancreas had the highest ADC value, then followed by PNET, PDCA, MFP and SPN. There was noticeable statistical difference in ADC values among PDCA, MFP and normal pancreas by Least Significant Difference (LSD) (p.001). ADC of SPN was statistically lower than that of PNET (p=0.1800×10(-4)), PDCA (p=0.0300×10(-4)) and normal pancreas (p=0.0007×10(-4)). ADC of PNET was statistically lower than that of normal pancreas (p=0.0360) and higher than that of MFP (p=9.3000×10(-4)).ADC measurements using RT-IR-DWI at 3.0T may aid to disclose the histopathological pattern of normal pancreas and solid pancreatic masses, which may be helpful in characterizing solid pancreatic lesions.

Introduction We aimed to evaluate the usefulness of magnetic resonance imaging (MRI) in the diagnosis of occult fractures of the scaphoid and to determine the advantages and cost in comparison with the traditional follow-up protocol. Materials and methods The traditional approach at our center consisted of immobilization and periodic clinical and radiological follow-up (plain-film X-rays and computed tomography in the final phase of the process). The new protocol called for a limited MRI study consisting of coronal T1- and T2-weighted fat suppression sequences if the findings at plain-film X-rays continued to be negative at the first follow-up examination with the traumatologist (10 days after trauma). We evaluated the MRI findings, the time the patient was immobilized, the cost of each protocol, and the dose of radiation received. Results We included 33 cases of patients with clinically suspected fractures of the scaphoid and negative findings on plain-film X-rays. In 13 patients, the MRI findings were negative. In 12 patients, the MRI findings confirmed the diagnosis of a fracture of the scaphoid, which was associated with other pathology in 6 cases. In 8 patients, another pathological process was diagnosed. The cost of the new protocol was €131.06 per patient; the cost of the traditional protocol was €114.41 or €151.06 per patient, depending on the follow-up studies required. The new protocol reduced the dose of radiation by eliminating successive radiologic studies. Conclusions The new protocol improved the management of these patients, reducing the time of immobilization, improving joint rigidity, and reducing the time off work. The limited MRI study makes it possible to diagnose other radiologically occult lesions. The cost of the new protocol is similar to that of the traditional protocol and even lower in some cases. The new protocol results in a reduction in the dose of radiation.

Objectives The purpose of this study is to determine the diagnostic accuracy of MR sialography in the examination of patients with salivary duct disease. Patients and methods Twenty-eight patients (twenty males and eight females, average age, 47 years), with symptoms related to the salivary glands, underwent both conventional sialography and MR sialography. The latter was performed using heavily T2-weighted, two dimensional, fast spin-echo techniques and a neck coil. Contiguous 3-mm axial images with frequency-selective fat suppression were acquired through the symptomatic gland. The MR sialography findings were compared with the final diagnoses determined by conventional sialography, and with surgery in the case of those who underwent surgical intervention. Ultrasound examination was performed using 7.5 MHz transducer. Conventional sialography was performed with the use of 0.012–0.021 inch sialographic catheter and an injection of 0.3–1.5 ml Ultravist 300 mg/ml. Results Final diagnosis included sialolithiasis in eleven cases, sialolithiasis and stenosis in four cases, stenosis without lithiasis in ten cases and normal salivary glands in three cases. (The normal cases were excluded from the study). Conclusion It is concluded that MR sialography with a heavily T2-weighted sequence is highly successful in the noninvasive visualization of the ductal system of major salivary glands in cases that could not be examined by conventional sialogram. It is useful for diagnosing sialolithiasis and ductal stenosis. However, normal MR sialographic findings do not allow the exclusion of small calculi. Thus in patients with strong clinical suspicion of calculi and normal MR sialographic findings, conventional sialography should still be performed.

When chemical shift selective (CHESS) imaging is used with magnetic resonance imaging (MRI) for simultaneous imaging of both hands for the evaluation of rheumatoid arthritis, the fat suppression effect is poor. We investigated whether these fat-suppressed images using CHESS could be improved with the use of rice pads. T1-weighted images were obtained with CHESS and the same imaging parameters were used with and without rice pads on the coronal plane of both hands in 10 healthy volunteers. Patients were placed in a prone position with both hands extended overhead. The fat-suppression effect was classified into four categories and scored for both sets of images, and visual assessments were made by one radiologist and one radiologic technologist. The evaluation score was 1.1 for the images made without rice pads, and 3.2 for the images made with rice pads. The fat suppression effect was thus significantly better in the images made using rice pads (P < 0.0001). Lingering fat signals disappeared almost completely in images of both hands using CHESS with rice pads, and it was confirmed that the images were improved and had good fat suppression. More accurate evaluation of inflammatory sites that occur in rheumatoid arthritis may thus be possible, promising better diagnostic accuracy.

Purpose To assess the performance and results of R2 relaxometry using a fat-suppressed (FS) multiecho sequence and compare these to conventional R2 relaxometry in estimating tissue iron overload. Materials and Methods Relaxation rate values (R2=1/T2) of the liver, spleen, pancreas and vertebral bone marrow (VBM) were estimated in 21 patients with β-thalassemia major, using a respiratory-triggered 16-echo Carr-Purcell-Meiboom-Gill (CPMG) spin-echo sequence before (R2) and after (R2 FS) the application of chemically selective fat suppression. Results Hepatic and splenic R2 FS values correlated with respective R2 values (r=0.98 and r=0.96, P Conclusion Application of fat suppression in the standard CPMG sequence improved the capability of MRI in noninvasive quantification of iron, particularly in lipid-rich tissues, such as vertebral bone marrow (VBM) and pancreas.

Bowel contents and peripheral nerves often show high signal intensity at diffusion-weighted imaging (DWI) of the abdomen and pelvis, obscuring or mimicking pathology. This study introduced and compared short tau inversion recovery (STIR) with single-axis DWI to the usual combination of spectral fat suppression (SFS) with trace DWI in the suppression of bowel contents and peripheral nerves. Five volunteers underwent both STIR with single-axis DWI and SFS with trace DWI of the abdomen and pelvis. Images were evaluated by two observers with respect to the suppression of signal of bowel contents and peripheral nerves using four-point grading scales (4=poor suppression; 3=moderate suppression; 2=good suppression; 1=excellent suppression). Mean scores (±S.D.) regarding the suppression of bowel contents were 1.60±0.55 and 1.40±0.89 for STIR with single-axis DWI and 3.40±0.55 and 3.00±1.00 for SFS with trace DWI for observers 1 and 2, respectively. Mean scores regarding the suppression of peripheral nerves were 1.20±0.45 and 1.20±0.45 for STIR with single-axis DWI and 2.40±0.89 and 2.80±0.84 for SFS with trace DWI for observers 1 and 2, respectively. In conclusion, STIR with single-axis DWI is superior to SFS with trace DWI in the suppression of bowel signal and peripheral nerves.

Optimized use of cross-sectional imaging for the early diagnosis andmanagement of ankylosing spondyloarthropathy It is becoming increasingly desirable to diagnose ankylosing spondyloarthropathy (AS) at its pre-radiographic stage (prior to the presence of sacro-iliitis on radiographs). MRI plays a key role for early diagnosis of AS, as illustrated by recently proposed international diagnostic criteria (ASAS). MRI of the SI joints is most helpful for early diagnosis; sequences using fat suppression and/or Gadolinium administration are necessary for the detection of inflammatory changes. However, the rate of false positive and false negative results of MR imaging of the SI joints, especially early in the course of the disease, is unknown and requires prudent interpretation of imaging findings. In patients with normal MRI examination of the SI joints and/or if symptoms are limited to the spine, MRI of the lumbar spine with STIR and/or Gadolinium administration may be helpful; again the positive and negative predictive values are unknown, especially early in the course of the disease. The demonstration of inflammatory changes on MRI, at the axial level, could be an indication for anti-TNF treatment, outside of WMA (national and international recommendations). The role of Doppler US, especially for peripheral entheses, remains hypothetical for early diagnosis. The role of MRI for structural evaluation is also being assessed even though radiographs remain the standard of reference. To date, no treatment, conventional or other, has been shown to have a structural effect (aside from limitations related to the methodology of available studies).

Objectives The aim was to investigate magnetic resonance (MR) and computerized tomography (CT) images and compare MR and CT image features of postoperative maxillary cysts (POMC). Study design We retrospectively evaluated MR and CT images of 7 POMC patients. Number of the cysts, border, bone expansion, CT value, signal intensity, and contrast enhancement were observed. Results On CT images, 15 cysts were detected. Fourteen cysts showed smooth border. Bone expansion was found in 10 cysts. Mean CT value of each cyst ranged from 23 to 50 Hounsfield units. On MR images, 18 cysts were detected. Twelve cysts showed smooth border. Bone expansion was not observed. Most cysts showed intermediate signal intensity on T1-weighted images, and high or nonhomogeneous intermediate/high signal intensity on T2-weighted images with the fat suppression technique. No cyst showed contrast enhancement in both examinations. Conclusion The CT images revealed bony information, and the MR images clearly demonstrated border of POMC. POMC should be evaluated with both CT and MR imaging.

Athletes with hip pain can have a variety of potential causes of the pain, including intra-articular pathology such as labral or cartilaginous injuries, as often seen in the setting of femoroacetabular impingement, surrounding soft-tissue pathology such as muscle or tendon injuries, and referred pain from stress injuries of the pubic bones, often from traction enthesitis from the adductors. With the use of dedicated surface coils, high-resolution noncontrast magnetic resonance imaging of the hip can provide detailed information regarding articular cartilage and labral injuries in the athlete with hip pain. The addition of a fat suppression sequence helps to identify areas of bone marrow edema that may be indicative of stress reaction or fracture. The three-dimensional capabilities of magnetic resonance imaging further afford the evaluation of osseous morphology of the hip, including the degree of osseous proliferative change and potential offset of the femoral head neck junction in the setting of femoroacetabular impingement.

The use of MR imaging in assessing lumbar bone marrow first requires an understanding of the bone marrow's normal composition and the various imaging sequences available for use. One of the most useful sequences is the T1-weighted spin-echo sequence. This sequence may be combined with other sequences such as T2-weighted or diffusion-weighted sequences; techniques such as fat suppression, chemical shift imaging, and contrast-enhanced imaging are discussed. The varying features of normal lumbar marrow related to the normal physiologic changes that occur with aging and with changes in hematopoietic demand are important to understand and are described. The appearances of infiltrative marrow disease are explained on the basis of marrow composition and whether disease causes proliferation, replacement, or depletion of normal marrow components.

In the era of molecular imaging, in vivo 1 H magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) are impacting dramatically upon virtually all areas of clinical medicine. MRS and MRSI should be able to identify key biochemical changes, much before the tumour becomes detectable by other functional imaging methods that mainly rely upon single markers that are not entirely sensitive or specific for malignant activity. Combined with other imaging techniques a rapidly advancing modality like MRI offer the ability to estimate the presence of metabolites yields much information regarding tissue. Molecular imaging through magnetic resonance could be potentially suited for screening and repeated monitoring since it entails no exposure to ionizing radiation. Incorporation of these tools in clinical practice is, however, limited due to the considerable amount of user intervention. In this work, various acquisition parameters and their effects in spectrum quality are investigated. In order to assess the quality of various spectroscopic techniques (2D and multi-slice MRSI, multiple echo SI), a series of experiments were conducted using a standard solution. The application of water and fat suppression techniques and their compatibility with other parameters were also investigated. The stability of the equipment, the appearance of errors and artifacts and the reproducibility of the results were also examined to obtain useful conclusions for the interaction of acquisition parameters. All the data were processed with specialized computer software (jMRUI 2.2) to analyze various aspects of the measurements and quantify various parameters such as signal-to-noise ratio (SNR), full-width at half-maximum (FWHM), peak height and j-modulation. The experience acquired from the conducted experiments was successfully applied in acquisition parameter optimization and improvement of clinical applications (two dimensional (2D) MRSI of prostate, brain and muscle MRS) by significantly improving the spectrum quality, SNR (up to 75%), spatial resolution in 2D MRSI, water and fat suppression and in some cases reducing exam times (up to 60%).

The basic principles of magnetic resonance imaging were presented in Part 1. Part 2 of this series addresses the use of contrast media and fat suppression, and the clinical applications of magnetic resonance imaging with regard to the face and jaws. These are implantology, temporomandibular joint disease, facial pain, facial swellings, malignancies, vascular lesions, infections and magnetic resonance imaging sialography.

Ankle injuries are estimated to constitute as many as 21% of sportsrelated injuries [1]. Both intra-articular and extra-articular injuries may be present, commonly with multiple concurrent injuries [2]. The clinical manifestations of many injuries may be subtle [1] or may overlap with other injuries [2]. Although plain film radiography has traditionally been the most common modality to image the ankle, MRI has taken a much more prominent role in recent years because of superior soft tissue resolution and the ability to noninvasively visualize the osseous structures, cartilage, and soft tissues of the ankle. In this review, we discuss the pertinent anatomy and common pathology seen in sports-related ankle injuries. IMAGING TECHNIQUE Magnetic resonance imaging techniques for the ankle vary between institutions. We employ a sagittal inversion recovery sequence, which provides homogeneous fat suppression over the curved ankle joint. Additionally, we use an intermediate echo-time, fast-spin-echo proton density technique for cartilage-sensitive imaging in three planes [3].

Rationale and Objectives To measure signal-to-noise ratio (SNR), contrast, and relaxation times (T1 and T2) in human knee joint at 7.0T whole-body scanner. Materials and Methods MRI experiments were performed on a 7.0T Siemens whole-body scanner using an 18-cm diameter transmit/receive knee coil. Normalized SNR and relaxation times (T1 and T2) were computed on all volunteers (healthy, n = 5) for femoral, tibial, and patellar cartilage. Results Average T1 values of femoral, tibial, and patellar cartilages were found as 1.55, 1.76, and 1.62 seconds, respectively. Average T2 values of femoral, tibial, and patellar cartilages were found as 51.3, 43.9, and 39.7 milliseconds, respectively. No statistically significant differences were observed between T1 and T2 values of different cartilage tissues (P > .08 for all comparisons). Compared with previously reported relaxation times of cartilage tissue at 3.0T, an ∼35% increase was observed in T1 values, whereas no significant change was observed in T2. Regional analysis was also performed to investigate the change in relaxation parameters for weight-bearing vs. non–weight-bearing areas. A statistically significant difference was observed in T2 of tibial cartilage (P = .009). The rest of the comparisons yielded insignificant differences (P > .32). Conclusion Our preliminary results demonstrate the feasibility of acquiring high resolution three-dimensional images of knee joint (with and without fat suppression) at 7.0T whole-body scanner.

We present computed tomography, magnetic resonance imaging and pathologic findings of a 52-year-old female with a giant dedifferentiated retroperitoneal liposarcoma in which well differentiated lipoma-like and dedifferentiated components are found together. Dedifferentiated components of the mass showed various degrees of enhancement and revealed no suppression with fat saturation techniques. The diagnosis of dedifferentiated liposarcoma should be kept in mind when a mass is found with retroperitoneal localization, intense of contrast enhancement, calcifications, invasion of adjacent tissues, necrosis and haemorrhage, and the absence of fat suppression. © 2004 Elsevier Ireland Ltd. All rights reserved.

Magnetic resonance imaging is the method of choice for the evaluation of brachial plexopathy. Knowledge of the anatomy and normal imaging appearance is required. High-resolution imaging technique is necessary with the use of adequate coils. Evaluation of the brachial plexus requires T1 weighted sequences in three plans, T2 weighted sequences with fat suppression and if necessary the study is completed with gadolinium injection sequences with fat suppression. A CISS sequence is used if a nerve root avulsion is suspected. The spatial resolution must be optimized with the use of adapted parameters. We illustrate a variety of pathologies that can involve the brachial plexus. The pathology includes trauma, primary (neurogenic tumors, lymphomatosis) or secondary tumors, radiation plexopathy or inflammatory polyneuropathy.

This pictorial essay depicts MR features of benign and malignant parotid tumors. Increased T2 signal intensity is suggestive of pleomorphic adenoma. Tumors with relatively low signal intensity on T2-weighted images are more likely to be malignant even when they are well-demarcated. Fat suppression technique improves the ability to define the boundaries of neoplatic or inflammatory lesions.

The purpose of the present study is to evaluate the background fat intensity suppression instability of each area in the head and neck region, and in the post-reconstruction with metal plate and myocutaneous flap, of patients with oral cancer using fat-saturated (FS) images. STIR and FS T2-weighted images at pre- and post-surgery in 59 patients with oral cancer were scored for uniformity of fat suppression and tissue conspicuity in each region of the head and neck. The scores of FS on uniformity of fat suppression pre-operatively were worse than those of STIR in the mandibular level, but not lesion and tissue conspicuity. However, the deterioration both of scores between pre- and post-surgery using FS was worse than that using STIR using metal plate and/or myocutaneous flap. At diagnosis, we should recognize on MR images using FS that instability of the status of fat suppression might be brought about by respective area and reconstruction with metal plate and myocutaneous flap of patients with oral cancer.

Repetitive overhead motions, such as those commonly employed in tennis, baseball, swimming, and football, can lead to primary rotator cuff impingement [1]. Primary impingement is often seen in middle-aged athletes who present with chronic pain and weakness associated with overhead sporting activities. Conversely, secondary impingement is typically a manifestation of glenohumeral instability and is more common in young athletes who employ overhead or throwing motions. Although less common, secondary impingement may also be seen in the setting of posterior superior impingement and scapulothoracic instability. Prompt and accurate diagnosis of impingement syndromes helps ensure timely and appropriate treatment of recreational and professional athletes. MR imaging is an accurate method of evaluating the rotator cuff, coracoacromial arch, and the subacromial-subdeltoid bursa [2,3]. In addition, MR imaging can often identify lesions responsible for instability and secondary impingement. This article addresses the role of MR imaging in evaluating the rotator cuff and the importance of MR imaging in identifying other lesions that may mimic rotator cuff pathology. A rationale for protocol design, including MR arthrography and the use of specialized positioning, such as abduction and external rotation (ABER), are discussed.

Introduction: Today, intermediate-weighted (IW) and T2-weighted (T2w) Turbo Spin Echo (TSE) sequences with fat suppression are most commonly used to clinically assess morphological abnormalities of joint structures. In addition, quantitative analysis of the musculoskeletal system using MR relaxometry techniques such as T2 mapping has gained interest in recent years. This is in particular the case for imaging of osteoarthritis, since T2 values can be used as a non-invasive biomarker of early degenerative disease of cartilage and meniscus. The acquisition of both morphological and quantitative sequences is however time consuming. We suggest using a fast quantitative T2 mapping technique that allows the generation of synthetic images with different TEs, allowing a significant decrease in acquisition time while preserving image quality in comparison to the consecutive acquisition of morphological and quantitative sequences.

Purpose: The purpose of this technical note is to describe an adaptation to normal positioning technique for magnetic resonance (MR) imaging of the wrist and to review current practice in the light of relevant literature. Methods: A number of positioning techniques for MR imaging of the wrist were reviewed and volunteers were positioned on the scanner table in order to arrive at the most comfortable position whilst maintaining the wrist in a suitable orientation for optimum image quality. An audit of patient comfort during a research study of early onset rheumatoid arthritis (RA) sufferers was carried out by questionnaire after their MR examinations. Results: Altering positioning technique for MR of the wrist resulted in maintenance of good image quality whilst enhancing patient tolerance of the examination. The patient comfort audit indicated that the positioning technique adopted was very tolerable and that, in general, discomfort and stiffness brought on by the scan was minimal. No sequences had to be repeated on any of the subjects due to either patient movement or poor fat suppression. Conclusions: A revision to previous practice in positioning for MR of the wrist has resulted in patients with early onset RA being able to tolerate a lengthy investigation in what is normally a difficult position. These changes have ensured that image quality has been maintained and also shown that attention to detail and taking time to prepare the patient prior to scanning is essential in completing a satisfactory examination.

AIM: The aim of this pictorial review is to describe applications of cholangiopancreatography (MRCP) using half-Fourier (HASTE) MR sequences. MATERIALS AND METHODS: 350 patients were imaged over a four-year period with a 1.54 Tesla Siemens Vision scanner and a phased array body coil. The HASTE MR sequence was applied in multiple planes with an acquisition time of 13 seconds allowing breath hold techniques. In addition, a single-shot technique provided single slice acquisitions with a thickness of 20 mm. A chemical fat suppression algorithm reduced intra-abdominal MR high signal. RESULTS: HASTE MRCP accurately determines the presence of level of biliary obstruction in up to 97% of patients. Common bile duct stones are detected with a sensitivity of 93%. Acute cholecystitis is depicted on HASTE MR as pericholecystic high signal in 41 45 (91%) patients and gall stones are detected with a 93% sensitivity. CONCLUSION: HASTE MRCP offers a non-invasive, rapid imaging method to evaluate the gallbladder, common bile duct and pancreas. Its multi-planar, fluid sensitive capabilities are of particular value in detecting common bile duct stones and acute cholecystitis.

SUMMARY The mechanisms involved in the generation of motion artifacts in MR imaging are complex and depend both on the type and direction of motion as well as on the parameters of the imaging sequence chosen. The methods used to control or reduce motion artifacts are multiple and the appropriate method for use with any given clinical situation will depend on the particular hardware and software of the MR imaging unit, the patient's clinical status, and the specific organ or disease state to be imaged. Some general guidelines for clinical use that are applicable in most scenarios can be defined, although preferences for the different techniques vary. Appropriate T1-weighted images of the upper abdomen and liver can be obtained with breath-hold T1-weighted gradient echo. These images should be acquired with inferior–superior spatial presaturation pulses to reduce vascular pulsation artifact and ghosting. The application of GMN will depend on the individual MR imaging system. If sufficient coverage cannot be obtained with gradientecho imaging, then conventional T1-weighted images with phase-encoding reordering is suggested. The addition of spatial presaturation pulses (inferior-superior) may be valuable. The use of fat suppression will further improve image quality by reducing ghost artefact and improving CNR, although SNR will decrease. T2-weighted imaging of the upper abdomen will depend greatly on the hardware and software of the MR imaging unit. Recent techniques of breath-hold T2-weighted imaging require faster and stronger gradients, and may not be universally available. If available, these techniques provide excellent anatomic detail, although image contrast (e.g., liver to spleen) may decrease. Respiratory-triggered FSE techniques are the preferred method of imaging in most centers, because the imaging time is considerably less than conventional T2-weighted imaging whereas the image quality is improved. Liver lesion detection capability of the various techniques is still under study. The addition of fat suppression appears to improve image quality further with an increase in lesion detection. By understanding the principles underlying motion artifacts, one can choose the appropriate method of artifact control tailored for the individual clinical situation. In addition, the recognition of the variable appearances of motion artifacts will prevent interpretive errors and misdiagnoses. Careful attention to motion artifact reduction techniques can greatly improve patient care.

The DIET (or d ual i nterval e cho t rain) sequence, a modification of the f ast s pin e cho (FSE) sequence that selectively reduces signal from fat in MR images, has been investigated. The DIET sequence uses an initial echo spacing longer than that of a conventional FSE sequence, thus allowing J coupling-induced dephasing to take effect. The sequence is evaluated theoretically, and its effectiveness on a hydrocarbon (1-pentene) is demonstrated numerically using density matrix calculations. The sequence is also evaluated experimentally using in vitro solutions and in vivo imaging. The efficacy of the sequence is compared for different lipid chemical structures, field strengths, and pulse sequence parameters.

The goal of our study was to compare a T2-weighted breathhold fast spin-echo (BHFSE) technique with T2-weighted nonbreathhold fast spin-echo (FSE) technique for characterizing cavernous hemangioma of the liver and differentiating this entity from malignant tumor.Eighteen patients with cavernous hemangiomas and 18 patients with malignant hepatic tumors were studied with T2-weighted MRI with a nonbreathhold FSE technique with and without fat suppression and with a BHFSE technique without fat suppression. Hepatic lesions were analyzed quantitatively using signal intensity (SI) and contrast-to-noise (C/N) ratio. In addition, images were qualitatively compared for accuracy in characterizing hepatic lesion.Quantitatively, hemangioma had significantly higher SI and C/N ratios than did the malignant tumor on every pulse sequence (P0.01). Qualitatively, all malignant tumors were correctly categorized; differentiation between cavernous hemangioma and malignant tumor was impossible in three cases of cavernous hemangioma with the three pulse sequences (92% accuracy, 100% sensitivity, and 83% specificity).T2-weighted FSE and BHFSE MRI shows comparable levels of accuracy for differentiating between hepatic cavernous hemangioma and malignant tumor. Because overlap may exist using quantitative measurement, morphologic patterns must be carefully analyzed, supporting that quantitative analysis and morphologic evaluation are complementary.

Magnetic resonance imaging is undergoing continual and progressive evolution. To make a high quality examination, some requirements are mandatory, such as high spatial and contrast resolution to identify lesions and high temporal resolution to characterize them. We review the most important new magnetic resonance technologies, both those which are already available and used in clinical practice and those which are still to be developed. We analyze such technologic and methodolgic features as magnetic field strength, gradients, surface coils, echoplanar imaging, fat suppression techniques and magnetization transfer, contrast agents, automatic injectors, image postprocessing, computer assisted diagnosis, magnetic resonance-guided biopsy and spectroscopy. All these factors are in continuous evolution and new technologies anticipate, in the near future, faster examinations with very high spatial and contrast resolution, with magnetic resonance-guided cytologic and histologic aspiration biopsies, as well as spectroscopic studies of previously identified lesions. To perform a correct, state-of-the-art magnetic resonance examination of the breast, we need high strength gradients with high slew rate and bilateral coils. Finally, we discuss new technologies and methods which will increase the accuracy of magnetic resonance studies of the breast, improving image quality and decreasing execution time. Thus, magnetic resonance spectroscopy, allowing in vivo biochemical tissue analysis, seems to have high potentials; even though they are still difficult to define, the technique is sure to have major diagnostic impact also in monitoring the results to different treatments.

Due to short relaxation times, fat has a high signal on magnetic resonance images (MRI). This high signal, easily recognized on MRI, may be useful to characterize a lesion. However, small amounts of lipids are more difficult to detect on conventional MRI. In addition, the high signal due to fat may be responsible for artifacts such as ghosting and chemical shift. Lastly, a contrast enhancing tumor may be hidden by the surrounding fat. These problems have prompted development of fat suppression techniques in MRI. Fat may be suppressed on the basis of its difference in resonance frequency with water by means of frequency selective pulses or phase contrast techniques, or on the basis of its short T1 relaxation time by means of inversion recovery sequences. Lastly, hybrid techniques combining several of these fat suppression techniques are also possible. The aim of this paper is to review the basic principles of all these fat suppression techniques and to exemplify their clinical use.

Rationale and Objectives. To assess magnetization transfer (MT) ratios of bone marrow at magnetic resonance (MR) imaging performed with and without fat suppression. Materials and Methods. The authors peformed MR imaging in 30 regions of normal bone marrow in 10 subjects by using four types of gradient-echo sequences: a combination of MT and fat-suppression techniques, only the fat-suppression technique, only the MT technique, and without MT or fat-suppression techniques. MT ratios of marrow obtained with and without the fat-suppression technique were quantitatively compared. Results. The average MT ratio of marrow with fat suppression was significantly higher than that without fat suppression (P Conclusion. Because bone marrow includes both water and fat, the MT ratio of marrow was underestimated when MT imaging was performed without fat suppression. A fat-suppression technique should be used.