Highly undersampled supraaortic MRA at 3.0 T: initial results with parallel imaging in two directions using a 16-channel neurovascular coil and parallel imaging factors up to 16.

PURPOSE: To present the feasibility of highly undersampled contrast-enhanced MRA (CE-MRA) of the supraaortic arteries with a 16-channel neurovascular coil at 3.0 T using parallel imaging in two directions with parallel imaging factors (PIF) up to 16. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. In a prospective study, MRA protocols including PIF of 1, 2, 4, 9 and 16 yielding a spatial resolution from 0.81×0.81×1.0 mm(3) to 0.46×.46×0.98 mm(3) were acquired. In 32 examinations, image quality and vascular segments were rated independently by two radiologists. SNR estimations were performed for all MRA protocols. RESULTS: The use of high PIF allowed to shorten acquisition time from 2:09 min down to 1:13 min and to increase the anatomic coverage while maintaining or even increasing spatial resolution down to 0.46×0.46×0.98 mm(3). The larger anatomic coverage that was achieved with the use of high PIF allowed for visualization of vascular structures that were not covered by the standard protocols. Despite the resulting lower SNR using high PIF, image quality was constantly rated to be adequate for diagnosis or better in all cases. CONCLUSION: The use of high PIF yielded diagnostic image quality and allowed to increase the anatomic coverage while maintaining or even improving spatial resolution and shortening the acquisition time.

Contrast material for abdominal dynamic contrast-enhanced 3D MR angiography with parallel imaging: intraindividual equimolar comparison of a macrocyclic 1.0 M gadolinium chelate and a linear ionic 0.5 M gadolinium chelate.

OBJECTIVE: The purpose of this study was to compare a macrocyclic 1.0 M contrast agent with a linear ionic 0.5 M contrast agent at equimolar dosage in regard to image quality and number of vessel segments visualized at abdominal dynamic contrast-enhanced 3D MR angiography. SUBJECTS AND METHODS: In an intraindividual comparative study, 15 patients (six women, nine men; mean age, 53 +/- 12.1 years; range, 25-72 years) underwent 32 1.5-T whole-body contrast-enhanced 3D MR angiographic examinations performed with parallel imaging technique. At random and in separate sessions, each patient was examined after IV injection of 0.1 mmol/kg body weight 1.0 M macrocyclic gadobutrol and 0.5 M linear ionic gadopentetate dimeglumine. Three-dimensional data sets were acquired in the arterial, portal venous, and venous phases with identical imaging protocols. Quantitative analysis included contrast measurements of vessels compared with adjacent background tissue (Student's t test). Qualitative analysis was performed independently by two radiologists with regard to visualization of arterial and venous vessel segments and overall image quality (Wilcoxon's test). RESULTS: Visualization of individual vessel segments was rated significantly better after administration of 1.0 M macrocyclic gadobutrol compared with 0.5 M linear ionic gadopentetate dimeglumine (p < 0.001). Overall image quality was superior with 1.0 M macrocyclic gadobutrol, but the difference was not significant. Vessel-to-background contrast after injection of 1.0 M macrocyclic gadobutrol was significantly higher (arterial phase, 0.90, p = 0.02; portal venous phase, 0.78, p = 0.0002; venous phase, 0.74, p = 0.0002) compared with 0.5 M linear ionic gadopentetate dimeglumine (arterial phase, 0.89; portal venous phase, 0.73; venous phase, 0.67). CONCLUSION: At abdominal contrast-enhanced 3D MR angiography, depiction of small abdominal vessels was significantly better and vessel-to-tissue contrast significantly higher with 1.0 M macrocyclic gadobutrol than with an equimolar dose of 0.5 M linear ionic gadopentetate dimeglumine.

Clozapine: acquittal of the usual suspect.

This report concerns the case of a 29-year-old male patient suffering from severe psychotic illness who had been satisfactorily treated with clozapine for 4 months. Clozapine had also been successfully administered during a psychotic episode 5 years previously. Though symptoms of psychosis were successfully controlled following the most recent psychotic episode, a medical consultation assessed that exacerbation of pancreatitis warranted discontinuation of the current antipsychotic treatment regime. Following a series of unsuccessful courses of neuroleptic medication, a magnetic resonance cholangiopancreaticography (MRCP) revealed marked cholecystolithiasis suggesting a biliary pancreatitis. Clozapine treatment was readministered following cholecystectomy. After 4 weeks of antipsychotic treatment the patient was discharged from hospital on clozapine monotherapy.

Embolization of varicocles: pretreatment sperm motility predicts later pregnancy in partners of infertile men.

PURPOSE: To identify predictors of future pregnancy in partners of infertile men undergoing embolization of varicoceles. MATERIALS AND METHODS: This study was conducted within local institutional review board guidelines, and written informed consent was obtained. In 223 clinically infertile men (age range, 18-50 years) with varicoceles and associated oligoteratoasthenospermia, endovascular embolization of the spermatic veins was performed with distal coil embolization and sclerotherapy. Additional anti-inflammatory treatment was initiated if required. Baseline clinical examination, semen specimen, and hormone level findings were compared to follow-up data. Posttreatment pregnancy rate of their healthy female partners was assessed with a standardized questionnaire. Unconditioned logistic regression was used to identify factors among all available clinical and laboratory data predicting treatment success (sired pregnancy during follow-up). RESULTS: A total of 226 of 228 varicoceles in 223 patients were successfully treated. Resolution of varicoceles at clinical examination and ultrasonography (US) was observed in 206 patients (92.4%). Three-month follow-up semen analysis in these patients showed significant improvement in sperm motility (P < .001) and sperm count (P < .001); however, average values remained in the abnormal range (World Health Organization guidelines). In 173 patients, follow-up data were successfully obtained, with pregnancy reported in 45 (26%). Baseline sperm motility was identified as the only significant pretreatment factor (standardized regression coefficient beta = 3.285, t = 7.560, P = .006) predicting sired pregnancy. Hormone levels, clinical grading of varicoceles, Doppler US findings, and other semen parameters did not reach statistical significance. CONCLUSION: Sperm motility prior to varicocele treatment in infertile men is an important predictor of later pregnancy.

Contrast-enhanced timing robust acquisition order with a preparation of the longitudinal signal component (CENTRA plus) for 3D contrast-enhanced abdominal imaging.

PURPOSE: To investigate a new image acquisition method that enables an accurate hepatic arterial phase definition and the visualization of contrast agent uptake processes in abdominal organs like liver, spleen, and pancreas. MATERIALS AND METHODS: A 3D turbo gradient echo method where a fat suppression prepulse is followed by the acquisition of several profiles was combined with an elliptical centric k-space ordering technique and 3D dynamic elliptical centric keyhole. The new k-space ordering method (CENTRA+) was validated experimentally. In an initial clinical evaluation phase the method was employed in five patients to assess the accuracy of the hepatic arterial phase definition and the visualization of the contrast uptake processes in dynamic scanning in abdominal organs like liver, spleen, and pancreas. RESULTS: In total, five patients were evaluated using the new k-space order. Our initial results indicate that the new k-space order allows consistent capture of the hepatic arterial phase. In dynamic scanning the extreme short temporal resolution obtained with 3D elliptical centric keyhole enables contrast enhancement to be followed in organs with fast contrast uptake characteristics. CONCLUSION: The elliptical centric nature of the new image acquisition method effectively allows capture of the contrast enhancement processes with good fat suppression.

4D time-resolved MR angiography with keyhole (4D-TRAK): more than 60 times accelerated MRA using a combination of CENTRA, keyhole, and SENSE at 3.0T.

PURPOSE: To present a new 4D method that is designed to provide high spatial resolution MR angiograms at subsecond temporal resolution by combining different techniques of view sharing with parallel imaging at 3.0T. MATERIALS AND METHODS: In the keyhole-based method, a central elliptical cylinder in k-space is repeated n times (keyhole) with a random acquisition (CENTRA), and followed by the readout of the periphery of k-space. 4D-MR angiography with CENTRA keyhole (4D-TRAK) was combined with parallel imaging (SENSE) and partial Fourier imaging. In total, a speed-up factor of 66.5 (6.25 [CENTRA keyhole] x 8 [SENSE] x 1.33 [partial Fourier imaging]) was achieved yielding a temporal resolution of 608 ms and a spatial resolution of (1.1 x 1.4 x 1.1) mm(3) with whole-brain coverage 4D-TRAK was applied to five patients and compared with digital subtraction angiography (DSA). RESULTS: 4D-TRAK was successfully completed with an acceleration factor of 66.5 in all five patients. Sharp images were acquired without any artifacts possibly created by the transition of the central cylinder and the reference dataset. MRA findings were concordant with DSA. CONCLUSION: 4D time-resolved MRA with keyhole (4D-TRAK) is feasible using a combination of CENTRA, keyhole, and SENSE at 3.0T and allows for more than 60 times accelerated MRA with high spatial resolution.

Whole-body high-field-strength (3.0-T) MR imaging in clinical practice. Part II. Technical considerations and clinical applications.

This is the second part of a two-part series on the clinical applications of high-field-strength (3.0-T) magnetic resonance (MR) imaging and spectroscopy. In this part, the current level of evidence regarding the use of higher magnetic field strengths for cardiac imaging techniques (including the assessment of cardiac anatomy and function), breast and pelvic imaging, musculoskeletal applications, pediatric imaging, and MR spectroscopy is presented. Published data are interpreted from the perspective of the clinical radiologist. Specific difficulties associated with high-field-strength MR for body imaging and for spectroscopic applications are reviewed and compared with the expected or documented added value of high-field-strength MR for clinical patient care. The overall number of studies published on clinical body high-field-strength MR is still small, and there is evidence for a clinical advantage for selected, but not all, body MR imaging applications. Even without published evidence, clinical experience suggests substantial clinical advantages for musculoskeletal and pediatric applications.

Cerebral arteriovenous malformation: Spetzler-Martin classification at subsecond-temporal-resolution four-dimensional MR angiography compared with that at DSA.

PURPOSE: To prospectively test the hypothesis that subsecond-temporal-resolution four-dimensional (4D) contrast material-enhanced magnetic resonance (MR) angiography at 3.0 T enables the same Spetzler-Martin classification (nidus size, venous drainage, eloquence) of cerebral arteriovenous malformation (AVM) as that at digital subtraction angiography (DSA). MATERIALS AND METHODS: Institutional ethics committee approval and written informed consent were obtained. In a prospective intraindividual comparative study, 18 consecutive patients with cerebral AVM (nine men, nine women; mean age, 41.9 years +/- 14.0 [standard deviation]; range, 23-69 years) were examined with 4D contrast-enhanced MR angiography and DSA. Four-dimensional contrast-enhanced MR angiography combined randomly segmented central k-space ordering, keyhole imaging, sensitivity encoding, and half-Fourier imaging, which yielded a total acceleration factor of 60. Fifty dynamic scans were obtained every 608 msec at an acquired spatial resolution of 1.1 x 1.4 x 1.1 mm. Four-dimensional contrast-enhanced MR angiograms were independently reviewed by one neuroradiologist and one neurosurgeon according to Spetzler-Martin classification, overall diagnostic quality, and level of confidence. Kendall W coefficients of concordance (K) were computed to compare reader assessment of image quality, level of confidence, and Spetzler-Martin classification by using 4D contrast-enhanced MR angiography and to compare Spetzler-Martin classification as determined with DSA with that at 4D contrast-enhanced MR angiography. RESULTS: Spetzler-Martin classification of cerebral AVM at 4D contrast-enhanced MR angiography and at DSA matched in 18 of 18 patients for both readers, which yielded 100% interobserver agreement (K = 1). Image quality of 4D contrast-enhanced MR angiography was judged to be at least adequate for diagnosis in all patients by both readers. In three of 18 patients, DSA depicted additional arterial feeders of cerebral AVM. CONCLUSION: Subsecond-temporal-resolution 4D contrast-enhanced MR angiography at 3.0 T had 100% agreement with DSA with regard to Spetzler-Martin classification of cerebral AVM. SUPPLEMENTAL MATERIAL: radiology.rsnajnls.org/cgi/content/full/2453061684/DC1.

The evaluation of articular cartilage lesions of the knee with a 3-Tesla magnet.

PURPOSE: This prospective study was performed to investigate whether 3-Tesla magnetic resonance imaging (MRI) provides an accurate assessment of the articular cartilage in clinical practice. METHODS: Forty patients with persistent knee pain and suspected cartilage lesions underwent 3-T MRI shortly before arthroscopy with the following sequences: axial/coronal/sagittal proton density-weighted turbo spin echo with spectral fat suppression, axial/sagittal 3-dimensional T1-weighted gradient echo with selective water excitation, and axial T2-weighted gradient echo (Intera 3.0T; Philips Medical Systems, Best, The Netherlands). Knee cartilage surfaces were divided into 6 regions; lesions detected on MRI were classified into stages I to IV and compared with the arthroscopic grading. RESULTS: For the 240 cartilage surfaces evaluated, the sensitivities, specificities, positive predictive values, and negative predictive values of 3-T MRI were 74%, 95%, 74%, and 95%, respectively, for the detection of grade IV lesions; 63%, 90%, 60%, and 91%, respectively, for grade III lesions; 62%, 90%, 57%, and 92%, respectively, for grade II lesions; and 29%, 95%, 39%, and 92%, respectively, for grade I lesions. CONCLUSIONS: In these preliminary clinical studies 3-T MRI provided convincing visualization of the hyaline cartilage with comparatively good diagnostic values. Nonetheless, it must be pointed out that the positive predictive values were low for all grades of lesions. Thus, when 3-T MRI suggests a cartilage defect, the probability that the arthroscopic finding corresponds exactly to the MRI result is between 39% and 74%. Therefore, the value of arthroscopy for a detailed assessment and grading of a cartilage disorder with regard to definitive planning of a therapeutic procedure cannot be replaced by 3-T MRI. LEVEL OF EVIDENCE: Level I, testing of previously developed diagnostic criteria in a series of consecutive patients with universally applied gold standard.

High spatial resolution contrast-enhanced MR angiography of the supraaortic arteries using the quadrature body coil at 3.0T: a feasibility study.

To examine whether the the increased signal-to-noise (S/N) available at 3.0T would permit the use of the quadrature body coil for high spatial resolution contrast-enhanced (CE) MR angiography (MRA), and whether the large FOV that was used in our routine 1.5T protocol would also be feasible at 3.0T. In a prospective study, 43 patients and five volunteers were examined on a clinical whole-body 3.0T MR unit (Intera, Philips Medical Systems, Best, The Netherlands) after institutional review board approval and informed consent. Three-dimensional CE MRA (T1 gradient echo-sequence with TR/TE = 5.7/1.93 msec.; acquisition time, 1:54 min.) using randomly segmented central k-space ordering (CENTRA) was acquired with the quadrature body coil, using over a FOV of 350 mm. A high-image matrix of 432x432 yielded a non-zero filled voxel size of 0.81 mm x 0.81 mm x 1.0 mm (0.66 mm(3)). For quantitative analysis, contrast ratios (CR) between vessels (S) and signal in surrounding tissue (ST) were calculated [(S-ST)/(S+ST)]. For qualitative analysis, image quality and presence of artifacts were rated by two radiologists in consensus on a five-point scale (1=excellent to 5=nondiagnostic). Digital subtraction angiography (DSA) served as the standard of reference in patients with vascular disease. In the five volunteers, 1.5T CE MRA using a phased array neurovascular coil was available for intraindividual comparison. 3.0T CE MRA was successfully performed in 48/48 subjects (100%). Mean CR+/- SD were 0.76 (139.30/182.42) and 0.87 (235.18/270.14) at 3.0T and 1.5T respectively . Mean image quality was 3.82+/-0.86. Intraindividual comparison between 1.5T and 3.0T CE MRA in the volunteers revealed no significant difference in image quality (4.2+/-0.74 vs 4.6+/-0.80; p>0.05). Vascular disease was correctly identified in 13/13 patients with DSA correlation. CE MRA of the supraaortic arteries is feasible at 3.0T using a large FOV of 350 mm. The signal gain at 3.0T enables high spatial resolution contrast-enhanced MR angiography by using the built-in quadrature body coil only.

Intra-individual comparison of image contrast in SPIO-enhanced liver MRI at 1.5T and 3.0T.

The purpose of the study was to examine if the higher susceptibility at 3.0 Tesla (T) compared to 1.5 T will affect the contrast in MR imaging of the liver after application of superparamagnetic iron oxide particles (SPIO). The study was approved by our institutional review board and informed consent was obtained. Seventeen healthy volunteers were examined in a prospective, intra-individual comparative study within one day on a 1.5 T and a 3.0 T MRI system. T2 weighted TSE sequences were acquired after bolus injection of a SPIO contrast agent. Image contrast and signal to noise ratio (SNR) were compared between the field strengths. Image contrast was calculated between the liver tissue and the kidneys / spleen / muscles and fluids. The students'T-test was used for statistical analysis. No influence of the higher field strength could be observed on image contrast except for the liver / muscle contrast. This was due to a distinct SNR increase of the muscle tissue at 3.0 T as a result of their relaxation properties. The higher susceptibility at 3.0 T compared to 1.5 T does not translate into a stronger signal attenuation of the SPIO enhanced liver parenchyma.

Female pelvis: MR imaging at 3.0 T with sensitivity encoding and flip-angle sweep technique.

This study had institutional review board approval; all 33 patients (mean age, 47 years +/- 16 [standard deviation]) gave informed consent. The aim was to prospectively evaluate the diagnostic image quality yielded by a 3.0-T T2-weighted turbo spin-echo magnetic resonance imaging sequence with a very short imaging time versus that yielded by a standard 3.0-T sequence at imaging of the female pelvis. Signal-to-noise ratio and delineation of gynecologic disorders were approximately equal between the two sequences. The majority of tissue contrasts were comparable, but contrast between fluid and muscle was significantly higher and motion artifacts were reduced (P < .001 for both) with the short imaging time sequence. The fast sequence maintained or improved image quality and thus seems to be advantageous for uncooperative patients.

High-field-strength MR imaging of the liver at 3.0 T: intraindividual comparative study with MR imaging at 1.5 T.

PURPOSE: To prospectively evaluate whether magnetic resonance (MR) imaging of the liver at 3.0 T is comparable to that at 1.5 T with respect to image artifacts, image quality, and diagnostic utility in terms of detection and characterization of focal liver lesions in patients with these lesions. MATERIALS AND METHODS: Patients provided informed consent after the study had been explained, and the institutional review board approved the study protocol. An intraindividual comparative study was performed in 21 patients (12 men and nine women; mean age, 58.7 years; range, 36-76 years) with a total of 79 focal liver lesions (benign and malignant) who were examined at 1.5- and 3.0-T MR imaging within 1 week. The imaging protocol consisted of T2-weighted turbo spin-echo (SE) sequences with or without fat suppression, as well as T1-weighted gradient-echo (GRE) sequences with or without gadolinium-based contrast agent. All images were rated independently by two radiologists with respect to types of artifacts (susceptibility, motion, pulsation, image homogeneity, and electrodynamic effects) and in regard to detectability and characterization of focal liver lesions. A modified sign test was used for statistical analysis (alpha < .2). RESULTS: Motion artifacts were significantly more pronounced in non-fat-suppressed T2-weighted turbo SE images at 3.0 T (P = .03), whereas pulsation artifacts were more pronounced (P = .19) in precontrast T1-weighted GRE 1.5-T images. No statistically significant differences (P < .2) were observed for the remaining artifacts and sequences. Of the 79 index lesions, a total of 76 were prospectively identified at 1.5-T imaging and a total of 77 were identified at 3.0-T imaging. CONCLUSION: MR imaging of the liver at 3.0 T, compared with that at 1.5 T, is feasible with equivalent image quality and diagnostic utility in terms of detection and characterization of focal liver lesions.

Dynamic contrast-enhanced breast MR imaging in men: preliminary results.

PURPOSE: To prospectively evaluate whether the descriptors of lesion features and the diagnostic criteria that have been established for breast magnetic resonance (MR) imaging in female patients may be used for differential diagnosis with breast MR imaging in male patients as well. MATERIALS AND METHODS: The study design was approved by the institutional review board; all patients gave informed consent. The Institutional Review Board and informed consent information applied to the prospective and any retrospective component of the study. Seventeen consecutive male patients (mean age, 53 years +/- 14) were referred for imaging of a palpable breast mass. In addition to mammography and high-frequency breast ultrasonography, patients underwent dynamic breast MR imaging in a prone position with a dedicated double-breast surface coil. The standardized protocol consisted of a T2-weighted turbo spin-echo sequence followed by a dynamic series. Findings were recorded by using the terminology and descriptors and by evaluating the diagnostic criteria (related to morphology and enhancement kinetics) that have been developed for breast MR imaging in female patients. Validation was achieved at biopsy (nine patients) or follow-up with clinical examination and conventional imaging (eight patients). Because of the small size of the patient cohort, statistical significance was not tested. RESULTS: A total of 24 breast abnormalities were diagnosed. Three patients had invasive breast cancer (five tumors), 11 had gynecomastia (six unilateral, five bilateral), two had pseudogynecomastia, and one had a benign solid tumor (angiolipoma). All malignant tumors appeared as irregular masses with heterogeneous internal architecture or rim enhancement and showed rapid initial enhancement (mean value, 137% +/- 23) followed by a washout time course (Breast Imaging Reporting and Data System [BI-RADS] category 5). Diffuse and nodular gynecomastia showed slow initial and persistent enhancement with normal-appearing parenchymal architecture (BI-RADS category 2; 15 of 16 breasts in 10 of 11 patients). In one patient with biopsy-proved bilateral gynecomastia, an area with segmental enhancement was classified as suspicious for ductal carcinoma in situ. Pseudogynecomastia did not enhance at all. The angiolipoma showed benign morphologic features and slow initial and persistent enhancement (BI-RADS category 2). CONCLUSION: In the small study cohort, the MR imaging features of benign breast diseases and breast cancers in male patients seemed to be comparable to those seen in female patients.

MRI of the pelvis at 3 T: very high spatial resolution with sensitivity encoding and flip-angle sweep technique in clinically acceptable scan time.

OBJECTIVE: The higher signal at 3.0-T allows spatial resolution to be increased without loss in image quality. We evaluated a T2-weighted turbo spin-echo sequence with high spatial resolution (3T-HR) to determine whether this provides clinically useful pelvic MRI. MATERIALS AND METHODS: We designed a sequence with high spatial resolution (3T-HR) (0.45x0.46x4 mm) that was combined with parallel imaging and the variable refocusing angle technique (8.06 min). We examined 23 patients with gynecological disorders using 3T-HR and a standard sequence (3T-SP; 4.03 min; equivalent to 1.5 T). Two radiologists analyzed tissue contrast, signal to noise, detail delineation and artifact level. RESULTS: Tissue contrasts and signal to noise were rated equal. Motion artifacts occurred more often with 3T-SP despite the longer scanning time of 3T-HR. The higher spatial resolution provided additional information in four patients. In two patients small myomas were detected, in one patient a lymph node metastasis was apparent, and in one patient 3T-HR excluded tumor invasion. CONCLUSIONS: High spatial resolution pelvic studies with high image quality can be obtained at 3 T in acceptable scan time. The higher spatial resolution that is feasible at 3 T also provides more clinically relevant information.

Pathological cervical fracture after spinal manipulation in a pregnant patient.

OBJECTIVE: To present the rare case of a displaced odontoid fracture after manipulative treatment. CLINICAL FEATURES: A 37-year-old, 15-week pregnant patient was referred with acute neck pain and a diffuse paravertebral swelling that started after cervical manipulation performed by her general medical practitioner 5 days before. Because of pregnancy, a cervical spine radiographic series was not obtained before treatment. Magnetic resonance imaging revealed a displaced odontoid fracture associated with a pathological process in the vertebral body of C2 and a paravertebral hematoma on the left side from C2 to C4. INTERVENTION AND OUTCOME: After initial halo vest immobilization, an anterior-posterior fusion of C1-C2 was performed. The histological analysis showed features of an aneurysmal bone cyst. The patient was discharged and had an undisturbed pregnancy and was without any neurological complications. CONCLUSIONS: Because of the weakening lesion in C2, the spinal manipulation most likely caused the displaced odontoid fracture. Special imaging should be performed, preferably with magnetic resonance imaging, when a patient experiences significant new symptoms after cervical manipulation.

Sensitivity encoding (SENSE) for contrast-enhanced 3D MR angiography of the abdominal arteries.

PURPOSE: To assess sensitivity encoding (SENSE) for contrast-enhanced MR angiography (CE-MRA) of the abdominal arteries in comparison with standard MRA protocols. MATERIALS AND METHODS: In 22 patients MRA of the abdominal arteries was performed twice (once using a standard protocol, and once with the additional use of SENSE). In 10 patients all examination parameters were kept constant (TR/TE/FA = 3.8 msec/1.3 msec/30 degrees ), and a reduction in scan time from 22 to 11 seconds was realized with the use of SENSE. In 12 patients, using SENSE the acquisition matrix was increased from 208 to 416, keeping the scan time constant. Image quality was scored on a five-point scale by three radiologists. Additionally, ROI-based measurements of CNR were performed. RESULTS: For both protocols, image quality was significantly improved using SENSE. The time-reducing SENSE protocol yielded an average score of 4.2 points vs. 3.1 for the standard protocol. Using SENSE to increase the acquisition matrix, an average score of 4.3 was reached vs. 3.2 for the standard protocol (P < 0.05). The number of depictable small vessels and their bifurcations was significantly increased by either of the two SENSE protocols as compared to the standard imaging procedure. CONCLUSION: SENSE for MRA of the abdominal arteries significantly increases image quality and permits a substantial reduction in breath-hold time or a significantly improved spatial resolution.

Sensitivity encoding for diffusion-weighted MR imaging at 3.0 T: intraindividual comparative study.

PURPOSE: To prospectively evaluate whether diffusion-weighted (DW) magnetic resonance (MR) imaging with sensitivity encoding (SENSE) at 3.0 T can help to improve image quality and confidence in and accuracy of diagnosis of ischemic lesions, compared with DW MR imaging with conventional phase encoding, in patients. MATERIALS AND METHODS: Patients provided informed consent after the study had been explained, and the institutional review board approved the study protocol. Eighty-five patients (46 male and 39 female patients; age range, 13-86 years; mean age, 52 years) underwent single-shot spin-echo echo-planar DW MR imaging at 3.0 T twice, in a randomized order: once with conventional phase encoding (repetition time msec/echo time msec, 4283/79) and once with SENSE (3141/69, with a reduction factor of three). With both, 128 x 128 matrix, 24 4-mm-thick sections, and two b values of 0 and 1000 sec/mm(2) were used. An eight-element SENSE-compatible receive-only surface coil was used; the built-in body coil served for radiofrequency transmission and generation of the coil sensitivity profile. SENSE and conventional phase encoding were compared for image quality, signal-to-noise ratio, relative signal intensity (SI), and lesion contrast. Two neuroradiologists read images. Diagnostic accuracy of and confidence in detection of apparent diffusion coefficient (ADC) lesions with conventional phase encoding and SENSE at MR imaging were compared; matched-pairs Wilcoxon signed rank test was used to test statistical significance. RESULTS: No major SENSE-related artifacts were seen. At MR imaging with SENSE, consistently and significantly (P < .001) higher image quality scores were achieved because of substantial reduction of image distortions and blurring. Lesion contrast was equivalent with both techniques. Diagnostic confidence for demonstration and exclusion of lesions was significantly (P < .001) higher at MR imaging with SENSE. In three patients, small microembolic lesions were only prospectively diagnosed at MR imaging with SENSE, whereas they were masked by adjacent susceptibility effects and therefore overlooked at MR imaging with conventional phase encoding. CONCLUSION: Parallel MR imaging with SENSE is feasible at 3.0 T. It significantly improves image quality, particularly by reducing or even preventing susceptibility-induced SI changes and image blurring. There was a significantly improved diagnostic confidence with which ADC changes were identified or excluded.

Acute and subacute ischemic stroke at high-field-strength (3.0-T) diffusion-weighted MR imaging: intraindividual comparative study.

PURPOSE: To compare signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), image quality, and confidence in diagnosis between 1.5- and 3.0-T diffusion-weighted (DW) magnetic resonance (MR) imaging of ischemic stroke lesions. MATERIALS AND METHODS: The study design was approved by the institutional review board, and all patients gave informed consent. In a prospective intraindividual study, 25 patients who had clinical symptoms consistent with ischemic stroke underwent DW MR imaging at both 1.5 T and 3.0 T. The 3.0- or 1.5-T examination was performed immediately one after the other, in random order. Two readers in consensus recorded the presence and number of ischemic lesions and rated image quality and lesion conspicuity. The image SNR and the CNR of the ischemic lesions were quantified. Paired Student t and Wilcoxon matched-pairs signed rank tests were used to test for statistical significance. RESULTS: Image quality at 3.0-T DW MR imaging was consistently lower than that at 1.5-T DW MR imaging owing to greater image distortions (P < .05). Yet, overall SNR and lesion CNR at 3.0 T increased significantly; mean increases were 48.8% (P < .001) and 96.3% (P < .01), respectively. The higher overall SNR and lesion CNR translated into a significantly higher sensitivity in the detection of ischemic lesions at 3.0 T than at 1.5 T. Of the total of 48 lesions that were identified in 19 of the 25 patients, 47 (98%) were diagnosed at 3.0 T and 36 (75%) were diagnosed at 1.5 T. In addition, the conspicuity of the lesions that were visible with both systems was significantly higher at 3.0 T (P < .001). CONCLUSION: Although 3.0-T DW MR imaging generates greater image distortions, it yields increased SNR and CNR compared with DW MR imaging at 1.5 T. The increased CNR at 3.0 T translates into a significantly improved diagnostic confidence in the detection of focal apparent diffusion coefficient changes in the setting of subacute and acute ischemic stroke.