T2 Turbo Spin Echo Research Articles

082 MRI for the detection of cerebral ischaemic events after transcatheter aortic valve replacement (TAVI): Abstract 082 Table 1

Background Trans-catheter aortic valve implantation (TAVI) is a rapidly expanding treatment for patients with severe aortic stenosis who are considered too high risk for conventional surgical aortic valve replacement (AVR). Stroke is a recognised complication of TAVI with a reported incidence of 0.6–10%. Diffusion weighted MRI of the brain has demonstrated a high incidence of clinically silent white matter lesions (WML) post-cardiac catheterisation (∼15%) or cardiac surgery (CABG ∼31% and conventional AVR ∼33%). Our study aimed to determine the incidence of new WML detected by diffusion weighted MRI pre- and post-TAVI (18F CoreValve system). Methods Fourteen patients underwent brain MRI scans immediately pre- and post-TAVI using a Phillips Intera 1.5Tesla scanner. The study was approved by the Leeds West Ethics Committee. Patients provided informed consent. Exclusion criteria were any contraindication to MRI (eg, permanent pacemaker). The MRI protocol included T2 Fast Field and Turbo Spin echo sequences and diffusion-weighted imaging. All scans were reported by a consultant neuroradiologist who was blinded to the clinical details. Results All 14 patients (64% female, age 81±16 years) completed both brain diffusion weighted MRI scans pre- (median 1 day, IQR 1–1.75) and post- (median 5 days, IQR 5–7) TAVI. Nine patients (64%) developed at least one new lesion post-TAVI. In the 14 patients there were a total 26 new lesions, with a median new lesion count of 1 (range 0–9). All new lesions were small in size ( Conclusions Patients undergoing TAVI are high risk individuals with multiple co-morbidities and a high predicted mortality. Subclinical stroke post-cardiac catheterisation or cardiac surgery has been well reported to be associated with future neurocognitive decline. Our small cohort experienced new white matter lesions (infarction) in 64% of patients, double the reported conventional surgical AVR rate, although by definition TAVI patients are much higher risk. Given the increasing survival and longevity of these patients this could have future implications on quality of life, post-operative cognition and cost (QALY9s).

Central trigeminal involvement in multiple sclerosis using high-resolution MRI at 3 T

Trigeminal neuralgia and sensory disturbance is common in multiple sclerosis (MS). Recent literature suggests that signal abnormalities in the cisternal trigeminal nerve and pontine root entry zone are seen in approximately 3% of MS patients, using conventional diagnostic MRI. The objective of this study was to determine the prevalence of trigeminal lesions using high-resolution MRI at 3T. Forty-seven patients with clinically definite MS, chosen at random from the outpatient population of a neuroscience centre underwent MRI on a Siemens 3T Trio machine. Three 3D sequences of T2 TSE (turbo spin echo), T2 FLAIR (fluid attenuated inversion recovery) and T1 IR (inversion recovery) were acquired in the coronal plane. The sequences were of contiguous 1 mm slices with in-plane resolution of up to 0.5 mm by 0.5 mm. Images were read by both a neurologist and a neuroradiologist. Any clinical history of trigeminal symptoms was determined for all subjects. The results showed that 11 patients (23%) had high signal in the trigeminal root entry zone and either the trans-cisternal nerve or pontine nucleus; example images are given. MRI changes did not correspond to clinical symptoms (chi square probability 1.000). The study concludes that high-resolution MRI at 3T yielded a high prevalence of detectable trigeminal abnormality in the MS sample studied. MRI involvement did not correspond to trigeminal symptoms.

Response to Comment on “Homeostatic Sleep Pressure and Responses to Sustained Attention in the Suprachiasmatic Area”

Astafiev et al . question whether the blood oxygen level–dependent (BOLD) response that we reported in the brainstem was located in the locus coeruleus (LC). Using high-resolution T1-turbo spin echo images (T1-TSE) acquired in an independent group of subjects, we show that the reported task-related BOLD response in the brainstem is actually compatible with the anatomical location of the LC.

Comparison of gadoxetic acid-enhanced MRI and superparamagnetic iron oxide-enhanced MRI for the detection of hepatocellular carcinoma

To compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced MRI and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC). Eighty-nine patients (118 HCCs) who underwent three-dimensional gadoxetic acid-enhanced MRI and SPIO-enhanced MRI with a mean interval of 4.7 days (range 3-7 days), were included in this study. Two observers reviewed the gadoxetic acid set (unenhanced, early dynamic, 10 and 20 min hepatocyte-phase images) and SPIO set [unenhanced and ferucarbotran-enhanced T1-, T2-turbo spin-echo (TSE), and T2* weighted imaging (WI)] in consensus. Diagnostic accuracy and sensitivity were evaluated using the alternative-free response receiver operator characteristic (ROC) method. The area under ROC curve (Az value) and sensitivity of the gadoxetic acid set (Az 0.964; sensitivity 90.7%) were significantly higher than those of the SPIO set (Az 0.830; sensitivity 84.7%; p<0.05). There were 14 and seven lesions that were verified only on the gadoxetic acid set and only on the SPIO set, respectively. Four HCCs were clearly revealed as hypointense only on gadoxetic acid-enhanced hepatocyte phase imaging, but were occult on other sequences, including the SPIO set. Gadoxetic acid-enhanced MRI is better than SPIO-enhanced MRI for the detection of HCCs.

Acetabular Labral Tears and Cartilage Lesions of the Hip: Indirect MR Arthrographic Correlation With Arthroscopy—A Preliminary Study

The purpose of this study was to assess the diagnostic correlation between indirect MR arthrography, conventional MRI, and arthroscopy in acetabular labral and cartilage lesions of the hip. Fourteen patients who underwent conventional and indirect MR arthrography with arthroscopic correlation were studied over the course of 18 months. MR studies were performed on a 1.5-T magnet. Sequences consisted of unilateral sagittal turbo spin-echo proton density fat-suppressed, axial turbo spin-echo T2 fat-saturated, and coronal turbo spin-echo proton density fat-saturated images. Whole-pelvis coronal T1 and STIR sequences were also performed. Patients received IV gadolinium contrast material and exercised for 15 minutes. Gadolinium-enhanced fat-saturated T1 sequences were obtained in three planes. Arthroscopy was performed by two orthopedic surgeons who specialize in treating hip disorders. Cases were then retrospectively reviewed by two experienced musculoskeletal radiologists who were blinded to the arthroscopic findings. Cases were examined for acetabular labral tears and chondral lesions. Extraarticular findings of femoral acetabular impingement were recorded. Unenhanced and gadolinium-enhanced images of the labrum were compared for differences and changes in diagnosis. Comparison was made between the arthroscopic and MR findings for analysis of the results. Of the 13 labral tears found at arthroscopy, 85% were detected by conventional MRI, whereas 100% were identified via indirect MR arthrography. Seventy percent of the labral tears identified on conventional MRI were better delineated by indirect MR arthrography. Identification of chondral abnormalities was not improved via indirect MR arthrography over conventional MRI. IV contrast-enhanced indirect MR arthrography appears to be an effective means of hip evaluation for labral tears. It does not appear to improve detection of cartilage abnormalities when compared with conventional MRI.

MAGNETIC RESONANCE SIGNAL CHANGES DURING TIME IN EQUINE LIMBS REFRIGERATED AT 4°C

When ex vivo magnetic resonance (MR) imaging studies are undertaken, specimen conservation should be taken into account when interpreting MR imaging results. The purpose of this study was to assess MR changes during time in the anatomic structures of the equine digit on eight cadaver limbs stored at 4 degrees C. The digits were imaged within 12 h after death and then after 1, 2, 7, and 14 days of refrigeration. After the last examination, four feet were warmed at room temperature for 24 h and reimaged. Sequences used were turbo spin echo (TSE) T1, TSE T2, short tau inversion recovery (STIR), and double-echo steady state (DESS). Images obtained were compared subjectively side by side for image quality and signal changes. Signal-to-noise ratio (SNR) was measured and compared between examinations. There were no subjective changes in image quality. A mild size reduction of the synovial recesses was detected subjectively. No signal change was seen subjectively except for bone marrow that appeared slightly hyperintense in STIR and slightly hypointense in TSE T2 sequence after refrigeration compared with day 0. Using quantitative analysis, significant SNR changes in bone marrow of refrigerated limbs compared with day 0 were detected in STIR and TSE T2 sequences. Warming at room temperature for 24 h produced a reverse effect on SNR compared with refrigeration with a significant increase in SNR in TSE T2 images. After 14 days of refrigeration a statistically significant decrease of SNR was found in bone marrow in TSE T2 and DESS sequences. The SNR in the deep digital flexor tendon was not characterized by significant change in SNR.

Magnetic Resonance Urethrography to Assess Obliterative Posterior Urethral Stricture: Comparison to Conventional Retrograde Urethrography With Voiding Cystourethrography

We prospectively evaluated magnetic resonance urethrography for depicting obliterative posterior urethral stricture. A total of 25 men with a mean age of 48.7 years (range 21 to 72) with complete posterior urethral stricture were studied preoperatively with axial and sagittal turbo spin-echo T2, sagittal T1 and contrast enhanced sagittal T1-weighted images. Of the 25 patients 22 underwent conventional retrograde urethrography with voiding cystourethrography. For magnetic resonance urethrography aseptic lubricant was infused through the external urethral meatus to dilate the distal urethra up to the stricture. Each imaging result was compared with a surgical specimen or a description of the surgical findings. Measurement errors were analyzed using the Wilcoxon signed rank test. The relationship between true and measured stricture length was evaluated by linear regression analysis. Based on magnetic resonance urethrography findings 2 patients with a less than 1 cm stricture were treated with internal urethrotomy, 21 with a more than 1 cm stricture underwent open urethroplasty and 2 with prostatic displacement and a 4 cm stricture needed the combined perineal and transpubic approach. The mean +/- SD measurement error on magnetic resonance urethrography imaging was significantly lower than that on conventional retrograde urethrography combined with voiding cystourethrography (0.4 +/- 0.4 vs 1.4 +/- 1.1 cm, p <0.001). Linear regression analysis showed a stronger linear relationship between magnetic resonance urethrography and surgical measurement (r(2) = 0.62, p <0.01). Magnetic resonance urethrography is more effective for evaluating obliterative posterior urethral stricture than retrograde urethrography combined with voiding cystourethrography.

Diffusion-Weighted Imaging of Surgically Resected Hepatocellular Carcinoma: Imaging Characteristics and Relationship Among Signal Intensity, Apparent Diffusion Coefficient, and Histopathologic Grade

The objective of our study was to determine the relationship between the signal intensity of hepatocellular carcinoma (HCC) assessed with diffusion-weighted imaging (DWI) and T2-weighted imaging and the apparent diffusion coefficient (ADC) with the histopathologic grade of each nodule. MR examinations including DWI and T2-weighted imaging of 125 surgically resected hypervascular HCCs in 99 patients were retrospectively reviewed. Pathologic examinations revealed 25 well-, 61 moderately, and 39 poorly differentiated HCCs. Two radiologists reviewed the images and classified the signal intensity of each tumor on DWI and T2-weighted imaging by mutual agreement. The incidence of each signal intensity and the relationship between signal intensity and histopathologic grade were assessed for each sequence. The relationship between the ADC and histopathologic grade was also evaluated. On DWI, 11 of 125 HCCs appeared hypo- to isointense, 27 tumors appeared slightly hyperintense, and the remaining 87 tumors appeared obviously hyperintense to the surrounding liver. Overall, 91.2% (114/125) of HCCs showed hyperintensity to the surrounding hepatic parenchyma. Statistical analysis showed that this rate on DWI was significantly higher than that on T2 turbo spin-echo (TSE) imaging (p < 0.001). On DWI, the tumors tended to show a brighter signal with rising histopathologic grade (p = 0.031), but this trend was not observed on T2-weighted imaging. ADC measurements revealed that the mean ADCs of well-, moderately, and poorly differentiated HCCs were approximately 1.45, 1.46, and 1.36 x 10(-3) mm(2)/s, respectively. There was no significant correlation between ADC and histopathologic grade. The histopathologic grade of HCC had no correlation with the ADC, but HCC tumors tended to show a higher signal on DWI as the histopathologic grade rose. However, predicting the correct histopathologic grade of each HCC before surgery on the basis of DWI findings was difficult because of the large overlap among histopathologic grades.

In vivo mapping of the human locus coeruleus

The locus coeruleus (LC) is a brainstem structure that has widespread cortical and sub-cortical projections to modulate states of attention. Our understanding of the LC's role in both normal attention and clinical populations affected by disrupted attention would be advanced by having in vivo functional and structural markers of the human LC. Evidence for LC activation can be difficult to interpret because of uncertainty about whether brainstem activity can be accurately localized to the LC. High resolution T1-turbo spin echo (T1-TSE) magnetic resonance imaging (MRI) (in-plane resolution of 0.4 mm×0.4 mm) was used in this study to characterize the location and distribution probability of the LC across 44 adults ranging in age from 19 to 79 years. Utilizing a study-specific brainstem template, the individual brainstems were aligned into standard space, while preserving variations in LC signal intensity. Elevated T1-TSE signal was observed in the rostral pons that was strongly correlated with the position and concentration of LC cells previously reported in a study of post-mortem brains (r=0.90). The elevated T1-TSE signal was used to produce a probabilistic map of the LC in standard Montreal Neurological Institute (MNI) coordinate space. This map can be used to test hypotheses about the LC in human structural and functional imaging studies. Such efforts will contribute to our understanding of attention systems in normal and clinical populations.

DIRECT IMAGING OF THE DISTAL DURAL RING AND PARACLINOID INTERNAL CAROTID ARTERY ANEURYSMS WITH HIGH-RESOLUTION T2 TURBO-SPIN ECHO TECHNIQUE AT 3-T MAGNETIC RESONANCE IMAGING

To evaluate the feasibility of the direct visualization of the distal dural ring (DDR) and adjacent anatomic structures in patients with paraclinoid internal carotid artery aneurysms at 3-T magnetic resonance imaging (MRI). Six consecutive patients (1 man, 5 women; mean age, 45.5 years; age range, 34-51 years) who underwent a 3-T MRI examination for the evaluation of 7 paraclinoid carotid artery aneurysms were reviewed retrospectively. MRI scans were acquired using a T2 turbo-spin echo sequence with 2-mm thickness without gap on the coronal plane perpendicular to the diaphragma sellae. Identifications of the DDR, adjacent regional anatomic landmarks, and paraclinoid aneurysms were analyzed. The locations of the paraclinoid aneurysms were categorized into intradural (aneurysm neck and sac located above the DDR), transdural (aneurysm neck or sac were straddling the DDR), and extradural (aneurysm neck and sac located below the DDR). Interstudy agreement between computed tomographic angiography and 3-T MRI for the anatomic location of the paraclinoid aneurysms was assessed in 6 patients who underwent both examinations. In all cases, the DDR was clearly identified and the relationship between the DDR and the paraclinoid aneurysm was successfully determined on 3-T MRI. The aneurysm locations determined with 3-T MRI were 4 intradural and 3 extradural. A comparison between computed tomographic angiography and 3-T MRI revealed discordant anatomic locations in 3 aneurysms (3 of 6, 50%). Direct visualization of the DDR as well as precise evaluation of paraclinoid aneurysm location with high-resolution 3-T MRI is possible. This study shows that high-resolution 3-T MRI is an important means to determine the appropriate management for patients with paraclinoid aneurysms.

Feasibility of MRI in Experimentally Induced Inflammatory Small Bowel Disease: A Pilot Study in a Porcine Model

The purpose of this study was to compare the macroscopic and microscopic findings of experimentally induced inflammatory lesions in jejunum and ileum with magnetic resonance imaging (MRI) findings. Inflammatory small bowel lesions were experimentally induced in six pigs. Bowel segments in jejunum and ileum were isolated, and a solution with trinitrobenzenesulfonic acid and ethanol (TNBS-EtOH) was installed. MRI of the small bowel was performed 7 days after surgery. Before the MRI examination, a 6% mannitol solution was installed through a nasogastric tube. The MRI protocol consisted of single-shot turbo spin echo T2 sequences, steady state free precession (BFFE) sequences, and a 3D T1 gradient echo sequence with fat saturation and intravenous contrast. The following image findings were evaluated: increased bowel wall thickness (BWT), increased bowel wall enhancement (BWE), and bowel stenosis. After the MRI examination, the animals were sacrificed. The small bowel was removed and examined macroscopically and microscopically. Inflammatory lesions developed in jejunum and ileum in all animals. The lesions were visible macroscopically and microscopically. The microscopic findings consisted of variable degrees of inflammation, ulcer formation, and fibrosis. In jejunum the inflammatory lesions were not diagnosed with MRI, except in one pig with a bowel necrosis probably caused by an intramural injection or leakage of the TNBS-EtOH solution. In ileum the bowel wall thickness was increased and the inflammatory lesions were diagnosed with MRI. In conclusion, the inflammatory lesions were visible macroscopically and microscopically. Lesions in ileum had increased BWT and were possible to image with MRI. Lesions in jejunum had normal BWT and were not diagnosed with MRI, except in one pig with increased BWT probably caused by complications to the installation of TNBS-EtOH.

A simple MRI protocol in patients with clinically suspected appendicitis: results in 138 patients and effect on outcome of appendectomy

To establish the value of breathhold magnetic resonance imaging (MRI) in the diagnosis of acute appendicitis. Over a 14-month period, 138 patients clinically suspected of having appendicitis were evaluated prospectively with MRI and comprised the study group. Fast turbo spin-echo breathhold T1, T2 and T2 fat suppression sequences were used in coronal and axial planes. The imaging results were recorded separately and subsequently correlated with clinical, radiological and histopathological follow-up. The effect of imaging strategies in patients suspected of appendicitis on hospital resources was calculated. Sixty-two of the 138 patients had a histopathologically proven appendicitis. MRI determined appendicitis in 63 patients, with one examination being false positive. The resulting sensitivity and specificity were 100% and 99%, respectively. MRI showed an alternative diagnosis in 41 of the 75 remaining patients. In 22 of the remaining 34 patients, a normal appendix was depicted with MRI. In two patients, where MRI showed no appendicitis, an alternative diagnosis or normal appendix, an unnecessary appendectomy was performed. The overall effect of using MRI in patients suspected of appendicitis on the use of hospital resources could have been a net saving between 55,746 euros and 72,534 euros. MRI has a high accuracy in detecting and excluding appendicitis, an alternative diagnosis or showing the normal appendix, and can be a valuable and cost-effective tool in the workup of patients clinically suspected of having appendicitis.

CLINICAL ANATOMY OF THE CANINE BRAIN USING MAGNETIC RESONANCE IMAGING

The purpose of this study was to produce an magnetic resonsnce (MR) image atlas of clinically relevant brain anatomy and to relate this neuroanatomy to clinical signs. The brain of a large mixed breed dog was imaged in transverse, sagittal, and dorsal planes using a 1.5 T MR unit and the following pulse sequences: Turbo (fast) spin echo (TSE) T2, T1, and T2- weighted spatial and chemical shift-encoded excitation sequence. Relevant neuroanatomic structures were identified using anatomic texts, sectioned cadaver heads, and previously published atlases. Major subdivisions of the brain were mapped and the neurologic signs of lesions in these divisions were described. TSE T2-weighted images were found to be the most useful for identifying clinically relevant neuroanatomy. Relating clinical signs to morphology as seen on MR will assist veterinarians to better understand clinically relevant neuroanatomy in MR images.

High-resolution and functional magnetic resonance imaging of the brachial plexus using an isotropic 3D T2 STIR (Short Term Inversion Recovery) SPACE sequence and diffusion tensor imaging

This technical note demonstrates the relevance of the isotropic 3D T2 turbo-spin-echo (TSE) sequence with short-term inversion recovery (STIR) and variable flip angle RF excitations (SPACE: Sampling Perfection with Application optimized Contrasts using different flip angle Evolutions) for high-resolution brachial plexus imaging. The sequence was used in 11 patients in the diagnosis of brachial plexus pathologies involving primary and secondary tumors, and in six volunteers. We show that 3D STIR imaging is not only a reliable alternative to 2D STIR imaging, but it also better evaluates the anatomy, nerve site compression and pathology of the plexus, especially to depict space-occupying tumors along its course. Finally, due to its appropriate contrast we describe how 3D-STIR can be used as a high-resolution mask to be fused with fraction of anisotropy (FA) maps calculated from diffusion tensor imaging (DTI) data of the plexus.

Magnetic Resonance Tracking of Magnetically Labeled Autologous Bone Marrow CD34+ Cells Transplanted into the Spinal Cord via Lumbar Puncture Technique in Patients with Chronic Spinal Cord Injury: CD34+ Cells' Migration into the Injured Site

The purpose of this study was to demonstrate the possibility of delivering autologous bone marrow precursor cells into the spinal cord via lumbar puncture technique (LP) in patients with spinal cord injury (SCI). Magnetic resonance imaging provides a noninvasive method for studying the fate of transplanted cells in vivo. Considering these propositions, we studied magnetic resonance tracking of autologous bone marrow CD34(+) cells labeled with magnetic nanoparticles delivered into the spinal cord via LP in patients with SCI. Sixteen patients with chronic SCI were enrolled and divided into two groups; one group got their own labeled-CD34(+) cells injected into the spinal cord via LP (n = 10); the others received an injection, but it contained magnetic beads without stem cells (controls, n = 6). CD34(+) cells were magnetically labeled with magnetic beads coated with a monoclonal antibody specific for the CD34 cell membrane antigen. Magnetic resonance images were obtained by a standard turbospin echo-T2 weighted sequences before and 20 and 35 days after post-transplantation. The median number of CD34(+) cells injected via LP was 0.7 x 10(6) (range 0.45 to 1.22 x 10(6)). Magnetically labeled CD34(+) cells were visible at the lesion site as hypointense signals in five patients of the labeled-CD34(+) group 20 and 35 days after transplantation; these signals were not visible in any patient of the control group. We suggested for the first time that autologous bone marrow CD34(+) cells labeled with magnetic nanoparticles delivered into the spinal cord via LP technique migrated into the injured site in patients with chronic SCI.

ASYMMETRIC SIGNAL INTENSITY IN NORMAL COLLATERAL LIGAMENTS OF THE DISTAL INTERPHALANGEAL JOINT IN HORSES WITH A LOW‐FIELD MRI SYSTEM DUE TO THE MAGIC ANGLE EFFECT

Increased signal intensity in one of the collateral ligaments of the distal interphalangeal (DIP) joint of sound horses in images acquired using a low-field magnet with vertical orientation of the magnetic field was investigated as a possible manifestation of the magic angle effect. Three isolated equine digits were imaged using the following pulse sequences: (1) spin echo TI, (2) turbo spin echo proton density and T2, and (3) 3D gradient echo T1, in different positions by mildly changing the orientation of the long axis of the digit, in the dorsal plane, relative to the magnetic field. The signal intensity in a ligament was significantly increased when the ligament orientation relative to the magnetic field was 55 +/- 10 degrees. The signal intensity was markedly increased in pulse sequences with short echo time (TE) 5.0, 4.9, and 3.9 times increased, respectively, for 3D gradient echo T1, spin echo T1, and turbo spin echo proton density) and to a lesser extent with pulse sequences with a longer TE (1.8 times increased for turbo spin echo T2). These changes are characteristic of the magic angle effect. Because of the anatomic orientation of the collateral ligaments of the DIP joint, a slight deviation of the long axis of the digit in the dorsal plane, from the ideal horizontal position, will induce an increased signal intensity that can be confused with desmitis. Careful positioning of the foot in magnetic resonance imaging systems where B0 is perpendicular to the long axis of the digit is critical to prevent the occurrence of the magic angle effect.

3D MRI in multiple sclerosis: a study of three sequences at 3 T

The objective of this study was to assess the feasibility of using 3D acquisition at 3 T for imaging patients with multiple sclerosis (MS). Feasibility was assessed by three criteria based on acquisition time, specific absorption rate (SAR) and image quality. 47 patients with clinically definite MS underwent imaging in a Siemens 3T Trio MR scanner. Patient safety data were obtained following the scan sessions. The study had local ethics approval. The following three-dimensional (3D) sequences, all acquired coronally, were used: T2 fluid attenuated inversion recovery (FLAIR) (repetition time (TR) 6000 ms, echo time (TE) 353 ms, inversion time (TI) 2200 ms), 0.5x0.5x1 mm voxels, acquisition time 10 min 38 s; T2 turbo spin echo (TSE) (TR 3000 ms, TE 354 ms), 1x1x1 mm voxels, acquisition time 8 min 29 s; T1 inversion recovery (IR) (TR 2040 ms, TE 5.56 ms, TI 1100 ms), matrix 512x448 (0.5x0.5 mm pixels), 0.5x0.5x1 mm voxels, acquisition time 7 min 38 s. Total acquisition time was 26 min 45 s. Example images are presented. 3D scanning at 3 T provides highly detailed, high quality images with acquisition times tolerated by MS patients, even by those with severe disability. The volumetric data are suitable for a wide variety of post-processing techniques; the authors suggest that 3D studies at 3 T should be considered as the possible brain imaging protocol for either cross-sectional or longitudinal studies in MS and that the 3D T2 FLAIR sequence should be considered for the purposes of radiological diagnosis.

Analyse der Bildqualität einer diffusionsgewichteten (EPI DWI) Sequenz: Untersuchungen an einem 1,5 T MRT mit höherer Gradientenfeldstärke : Analysis of MR image quality of echo planar diffusion -weighted imaging: investigations at 1.5 Tesla with higher gradient field strength

Purpose: Single – shot echo planar Diffusion – weighted – Imaging (EPI DWI) requires extended gradient facilities with strong, fast switching gradients. Up to now the image quality of EPI DWI is enormously influenced by some kinds of artifacts. Therefore we evaluated the image quality of EPI DWI in demonstrating anatomical structures using a 1.5 T MR scanner with a higher gradient field strength of 40 mt/m, a risetime of 200 μs and a slewrate of 200 T/m/s. Materials and methods: Using an evaluation scale with four categories two independent readers evaluated 12 different infra – and supratentorial anatomic regions of the brain on 50 DWI images and compared them with the corresponding T2 turbospin echo image. Results: No region was judged to be undistinguishable. On axial DWI images the assessment of the brain stem was poor. In the level of the putamen and thalamus the image quality of DWI was judged to be from adequate to excellent. The central sulcus and the boundary of the white and grey matter was assessed to be adequately visible. The interobserver variability showed a good agreement between the two readers. Conclusion: The image quality of EPI DWI improves from a higher gradient field strength. The shortening rise time of 200 μs and the slewrate of 200 T/m/s will lead to a faster gradient switching. Single shot EPI DWI is less influenced by image artefacts and the presentation of different anatomical structures profits when a MR scanner with higher gradient field strength is used.

Quality of life of patients after permanent prostate brachytherapy in relation to dosimetry: Van Gellekom MPR, Moerland MA, Van Vulpen M, Wijrdeman HK, Battermann JJ, Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands

To investigate changes in quality of life (QoL) after permanent prostate brachytherapy and to correlate these changes with postimplant dosimetry based on magnetic resonance (MR) images. For this study, 127 patients with low-stage prostate cancer and treated with brachytherapy received a QoL questionnaire at five time points: before treatment and at 4 weeks, 6 months, 1 year, and 2 years after treatment. The questionnaire included the RAND-36 generic health survey, the cancer-specific European Organization for Research and Treatment of Cancer (EORTC) core questionnaire, the tumor-specific EORTC prostate cancer module, and the American Urological Association symptom index. Postimplant dosimetry was based on registered T1 spin echo transversal, T2 turbo spin echo transversal, and T2 turbo spin echo sagittal MR images and CT images taken 4 weeks after implantation of the iodine-125 seeds. Calculated parameters were prostate volume, prostate volume receiving 100% (V100) and 150% (V150) dose, dose to 90% of the prostate volume (D90), maximum dose in 1-, 2-, and 5-cm3 rectum volume, distance between prostate and anterior rectum wall, and the maximum dose in 1%, 2%, and 5% urethra volume. Analysis of variance for repeated measures was used for comparison of the means of all variables in the different questionnaires. Linear regression analysis (stepwise) was used to investigate the correlations between QoL parameters and dosimetry parameters. On average, only the QoL at 4 weeks after implant was significantly different from (worse than) the QoL at the other time points. Regression analysis showed a significant correlation between changes in bowel problems and the maximum dose in 2-cm3 rectum volume, between changes in urinary symptoms and prostate volume, and between changes in urinary problems and the D90 value of the prostate. The QoL for patients with permanent prostate implants was worse in the first months after treatment but returned to baseline values 1 year after implant. Significant correlations were found between dose distribution and QoL.

Incidence of visualization of the normal appendix on different MRI sequences

The purpose of this paper is to assess the incidence of visualization of the normal appendix on magnetic resonance imaging (MRI) examinations of the pelvis in a large adult population and to compare the yield of commonly used sequences. Pelvic MRI scans of 111 randomly selected patients were retrospectively reviewed by two fellowship-trained body imagers. Thirty-six cases, where the entire cecum and terminal ileum were not included in the field of view, were excluded. A normal appendix was definitively visualized in 55 of 71 patients on T1 spin echo (SE) sequences (78%). The appendix was seen on 25 of 42 (60%) half-Fourier single-shot turbo spin echo T2. Visualization rates were 42% on pre-gadolinium T1 FS GRE, 54% on post-gadolinium T1 fat-suppressed gradient echo, and 17% of short tau inversion recovery sequences. MRI is an effective modality for visualization of the normal appendix. This may have important implications in patients with abdominal or pelvic pain, as visualization of a normal appendix should exclude the possibility of acute appendicitis from the differential diagnosis.