Fast Spin-echo MR Research Articles

Acute occlusive ischemia of the rat intestine: early detection by MR imaging with polylysine-Gd-DTPA enhancement.

The purpose of this study was to assess the potential role of MR imaging with polylysine-Gd-DTPA enhancement in the early detection of acute occlusive intestinal ischemia in a rat model. After devascularization of the distal ileum in 12 rats, T2-weighted fast spin-echo MR images were acquired, followed by T1-weighted images before and after IV administration of 0.1 mmol/kg polylysine-Gd-DTPA. The signal intensity of the ischemic intestine did not differ significantly from that of the normal intestine before the administration of the contrast material. No mucosal or submucosal edema or hemorrhage was found in the ischemic intestine at histologic examination. After the administration of polylysine-Gd-DTPA, the ischemic intestine lacked enhancement and its signal intensity was significantly lower than that of the normal intestine. MR imaging with polylysine-Gd-DTPA enhancement can detect acute occlusive ischemia of the rat intestine at an early stage.

Separation of fat and water in fast spin-echo MR imaging with the three-point Dixon technique.

A method for suppressing fat in fast spin-echo imaging with the three-point Dixon technique is described. The method differs from the three-point Dixon method used in conventional spin-echo imaging in that the readout gradient instead of a radio-frequency pulse is shifted. This method preserves the Carr-Purcell-Meiboom-Gill nature of the fast spin-echo sequence and hence is less sensitive to magnetic field inhomogeneities and resonance frequency mistuning. As in the original three-point Dixon technique used in conventional spin-echo imaging, three acquisitions are required to estimate the field inhomogeneity and completely separate fat and water. The extra time required is not excessive considering that the fast spin-echo method is frequently applied with multiple signal acquisition. Also, this technique achieves an expected signal-to-noise ratio comparable to 2.67 signal acquisitions, which is approximately 94% of the signal-to-noise ratio obtained with three signal acquisitions. The method is demonstrated with applications to phantoms and a human volunteer.

Breath-hold fast spin-echo MR imaging of the liver: a technique for high-quality T2-weighted images.

HomeRadiologyVol. 194, No. 2 PreviousNext Breath-hold fast spin-echo MR imaging of the liver: a technique for high-quality T2-weighted images.J W ReinigJ W ReinigJ W ReinigPublished Online:Feb 1 1995https://doi.org/10.1148/radiology.194.2.7824701MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In Article HistoryPublished in print: 1995 FiguresReferencesRelatedDetailsCited ByAbdominal RadiologyEuropean Radiology, Vol. 31, No. 11Pediatric Radiology, Vol. 47, No. 5Radiologic Clinics of North America, Vol. 53, No. 3Korean Journal of Radiology, Vol. 16, No. 5Academic Radiology, Vol. 17, No. 3Hepatic Lesions: Improved Image Quality and Detection with the Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction Technique—Evaluation of SPIO-enhanced T2-weighted MR Images1Yuusuke Hirokawa, , Hiroyoshi Isoda, , Yoji S. Maetani, , Shigeki Arizono, , Kotaro Shimada, , Tomohisa Okada, , Toshiya Shibata, , and Kaori Togashi, 1 May 2009 | Radiology, Vol. 251, No. 2Journal of Magnetic Resonance Imaging, Vol. 26, No. 2American Journal of Roentgenology, Vol. 184, No. 2Magnetic resonance imaging: TechniquesClinics in Liver Disease, Vol. 6, No. 1Journal of Magnetic Resonance Imaging, Vol. 16, No. 2Magnetic Resonance in Medicine, Vol. 47, No. 3Surgical Oncology, Vol. 10, No. 4Liver Lesion Conspicuity: T2-weighted Breath-hold Fast Spin-Echo MR Imaging before and after Gadolinium Enhancement—Initial Experience1Yong Yeon Jeong, , Donald G. Mitchell, , and George A. Holland, 1 May 2001 | Radiology, Vol. 219, No. 2Clinical Imaging, Vol. 25, No. 2Journal of the American Society of Nephrology, Vol. 11, No. 8Magma: Magnetic Resonance Materials in Physics, Biology, and Medicine, Vol. 9, No. 1-2Chirurgie, Vol. 124, No. 2Journal of Magnetic Resonance Imaging, Vol. 8, No. 3Clinical Imaging, Vol. 22, No. 3Magnetic Resonance Imaging Clinics of North America, Vol. 5, No. 2Journal of Magnetic Resonance Imaging, Vol. 6, No. 4Magnetic Resonance in Medicine, Vol. 36, No. 5Recommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 194, No. 2 Metrics Altmetric Score PDF download

Diagnosis of choledocholithiasis: value of MR cholangiography.

T2-weighted fast spin-echo MR imaging (MR cholangiography) of the right upper quadrant of the abdomen depicts the biliary tree in considerable detail. We studied the value of this procedure for detecting stones in the common bile duct in a series of patients with proved calculi. MR images of 10 consecutive patients with stones in the common bile duct were retrospectively reviewed. The diagnosis of choledocholithiasis was proved by stone extraction in all cases. Axial, coronal, and oblique images were obtained by using heavily T2-weighted fast spin-echo sequences, and the images were processed by using a maximum-intensity-projection (MIP) algorithm and a commercially available multiplanar reformatting software. Two reviewers who were not blinded to the diagnosis analyzed hard copy images and reformatted images at the MR console. The rate of stone detection was evaluated for each acquisition plane. The mean stone/bile signal-intensity ratio and the number and size of stones were recorded. In all patients, the entire length of the extrahepatic bile ducts was visualized, and the diagnosis of choledocholithiasis could be made on the basis of findings on MR images. Eight stones, including two that were impacted in the ampulla, were located in the distal part of the common bile duct. On the hard copy films, the stones were visible in eight of 10 coronal images, six of 10 axial images, and four of 10 oblique images. On the three-dimensional (3D) MIP reconstructions, the stones were seen in five of the coronal sets and in six of the axial sets. The best results were obtained when the multiplanar reconstruction software was used: nine of the 10 coronal sets and eight of the 10 axial sets showed stones in the bile ducts. By use of a combination of 3D MIP and multiplanar reconstruction, choledocholithiasis was detected in all 10 patients. The mean signal intensity of the stones was 58 (range, 18-87). The mean stone/bile signal-intensity ratio was 0.15 (range, 0.05-0.24). In this preliminary study, we showed that MR cholangiography, based on T2-weighted fast spin-echo sequences, could be an important imaging technique for patients with suspected bile duct obstruction and equivocal sonography and/or CT results. However, a large prospective clinical trial is needed to confirm these results.

MR detection of white matter disease of the brain in patients with HIV infection: fast spin-echo vs conventional spin-echo pulse sequences.

Although fast spin-echo images and slower spin-echo images have similar contrast characteristics, the two techniques have not yet been shown to be equivalent in all aspects of brain imaging. To determine if the two sequences are equivalent, we compared detection of white matter lesions, image quality, and artifact degradation on fast spin-echo and spin-echo proton density-weighted and T2-weighted MR images of the brain in prospectively selected patients who were seropositive for HIV. Fast spin-echo and spin-echo MR images of the brain were obtained in 153 consecutive subjects. The images were reviewed independently by three experienced neuroradiologists. The size, number, and location of white matter lesions were compared for the two techniques. Image quality, motion artifact, CSF flow artifact, and gray-white matter differentiation were graded on a five-point scale. No statistical difference was found in gray-white matter differentiation. Overall image quality, CSF flow artifacts, and motion artifacts were slightly worse on the fast spin-echo images (p < .05). Although some variability existed in the detection of lesions less than 5 mm in diameter, the differences was small, and all larger lesions were detected by both techniques. Agreement between fast spin-echo and conventional spin-echo techniques was nearly exact with respect to characterizing findings in brain as either normal or abnormal. Fast spin-echo and spin-echo MR of the brain produce images of similar quality and show white matter lesions equally well. These results support the replacement of slower, conventional spin-echo pulse sequences with faster fast spin-echo sequences.

MR imaging of high-grade cerebral gliomas: value of diffusion-weighted echoplanar pulse sequences.

The purpose of this study was to evaluate the usefulness of diffusion-weighted echoplanar MR imaging in the examination of high-grade brain gliomas compared with that of conventional spin-echo (SE) or fast spin-echo (FSE) MR imaging. We hypothesize that diffusion-weighted MR imaging may enable us to differentiate various tumor components on the basis of differences in the diffusion of water. Conventional SE and FSE MR images were obtained in 10 patients with high-grade brain glioma. Diffusion-weighted echoplanar MR images were obtained with a head gradient coil capable of providing diffusion-weighted imaging along the cephalocaudal axis. Using SE and FSE MR images as a baseline, we evaluated the diffusion-weighted MR images for usefulness in distinguishing tumor components on the basis of differences in diffusion. Areas of tumor that showed significant enhancement on T1-weighted SE MR images obtained after injection of contrast material were markedly hyperintense on diffusion-weighted images and had a lower apparent diffusion coefficient (ADC) than the ADCs for nonenhancing tumor and peritumoral edema. Cystic or necrotic portions of tumor showed the most signal suppression on diffusion-weighted images and were associated with the highest ADCs. On T2-weighted FSE MR images, areas of hyperintensity observed in white matter oriented parallel to the direction of the diffusion gradient could be differentiated into two patterns on the basis of findings on diffusion-weighted images: areas that showed marked signal suppression with a higher ADC, most likely representing areas of predominantly peritumoral edema, and areas that showed a lesser degree of signal suppression with similar but slightly lower ADCs than those of edema, most likely representing areas of predominantly nonenhancing tumor. Diffusion-weighted echoplanar MR imaging is a useful technique for examining high-grade cerebral gliomas. It enabled us to differentiate various components of the tumor (e.g., enhancing, nonenhancing, cystic, or necrotic) and to distinguish areas of predominantly nonenhancing tumor from areas of predominantly peritumoral edema when the abnormality was located in the white matter aligned in the direction of the diffusion-weighted gradient. Diffusion-weighted echoplanar MR imaging appears to be a powerful tool in the characterization of brain neoplasms.

Evaluation of malignant biliary obstruction: efficacy of fast multiplanar spoiled gradient-recalled MR imaging vs spin-echo MR imaging, CT, and cholangiography.

Although CT and cholangiography have proven value in the detection of biliary obstruction, determining the extent of biliary tumors and imaging small pancreatic or ampullar tumors remain problematic. We hypothesized that the superior contrast resolution of MR, coupled with contrast-enhanced breath-hold imaging, might increase the sensitivity for tumor detection and improve the depiction of the point of obstruction in patients with malignant biliary disease. Twenty-one MRI studies were performed prospectively in patients with malignant biliary obstruction by obtaining breath-hold contrast-enhanced fast multiplanar spoiled gradient-recalled (FMPSPGR) images at 0 and 10 min, conventional spin-echo T1-weighted images, and fast spin-echo T2-weighted images. Findings on MR images were correlated with findings on CT scans (15 cases) and/or cholangiograms (14 cases) by two observers. All MR images, CT scans, and cholangiograms were reviewed to evaluate tumor detection, visualization of dilated bile ducts, and conspicuity of the obstructing tumor. A four-point scale (1 = excellent tumor depiction and conspicuity, 4 = tumor not detected) was used for evaluation. Contrast-to-noise ratios for tumor and bile were calculated for the three MR pulse sequences. The contrast-enhanced FMPSPGR images and CT scans provided excellent depiction of the dilated biliary tree in 95% and 93% of examinations, respectively, with both techniques superior to fast spin-echo and T1-weighted images (p < .005). Tumor detection was best with the immediate FMPSPGR MR images (20/21), compared with fast spin-echo MR images (16/21) (p = .04), T1-weighted MR images (16/21) (p = .04), CT scans (12/15) (p > .05), and cholangiograms (13/14) (p > .05). Of 13 examinations showing proximal biliary obstruction, the mean score for tumor conspicuity was best with the immediate enhanced FMPSPGR MR images (1.38 +/- .65), compared with T1-weighted MR images (2.38 +/- 1.3) and fast spin-echo MR images (2.08 +/- 1.0) (p < .05), but it was not different from the delayed FMPSPGR MR images (1.75 +/- 1.1) or CT scans (1.9 +/- 0.99) (p > .05). For five of six cholangiocarcinomas, the immediate and delayed enhanced FMPSPGR MR images showed excellent tumor conspicuity owing to their enhancement with gadopentetate dimeglumine. Data for contrast-to-noise ratios of tumor showed that the immediate FMPSPGR MR images (15.8 +/- 10.2) were superior to T1-weighted images (6.3 +/- 3.5, p < .01), but were not different from fast spin-echo images (13.5 +/- 6.7) or delayed FMPSGR images (11.5 +/- 8.9). For eight examinations in patients with distal biliary obstruction, the mean score for tumor conspicuity was greater with the immediate FMPSPGR MR images (1.38 +/- 0.52), compared with fast spin-echo images (3.25 +/- 0.71, p < .005), T1-weighted images (2.63 +/- 1.06, p < .05), and delayed FMPSPGR MR images (2.60 +/- 1.5, p < .05), but was similar to that with CT scans (1.40 +/- 0.89, p > .05). Data for contrast-to-noise ratios of tumor showed an advantage for the immediate FMPSPGR MR images (12.0 +/- 7.7) over T1-weighted images (4.0 +/- 2.6, p < .01) and delayed FMPSPGR images (4.3 +/- 2.6, p < .025), but no difference from fast spin echo images (6.6 +/- 8.8, p = .05). Contrast-enhanced FMPSPGR MR imaging is sensitive for the detection of tumors causing biliary obstruction. For proximal obstruction, it may be particularly effective for detecting and defining tumor extent of hilar cholangiocarcinomas because of their enhancement with gadopentetate dimeglumine. For cases of distal obstruction, this technique showed improved tumor detection and conspicuity compared with T1- and fast spin-echo T2-weighted images, but showed no advantage over CT.

Silicone breast implant rupture: comparison between three-point Dixon and fast spin-echo MR imaging.

This study was designed to compare the three-point Dixon technique with our present MR protocol incorporating T2-weighted fast spin echo and fast spin echo with water suppression to detect ruptured silicone breast implants. Eighty-two symptomatic women with silicone breast implants were examined with both the three-point Dixon technique and fast spin-echo MR sequences. Of these patients, 41 had surgery to remove their implants. Four radiologists reviewed the images from only those patients who had surgery and graded each for rupture by using a scale of 1-5. Receiver-operating-characteristic analysis was performed. Of 81 implants removed, 18 were ruptured. Silicone implant ruptures were identified more frequently on the fast spin-echo sequence than on the three-point Dixon sequence, with areas under the ROC curves of .95 and .84, respectively. Although the difference was not statistically significant, the sensitivity for detecting silicone implant rupture was 89% for the fast spin-echo sequence and 61% for the three-point Dixon sequence. The specificity was 97% for both sequences. Silicone implant ruptures were detected more frequently with fast spin-echo MR sequences than with the three-point Dixon technique, although the difference was not significant. The greater spatial resolution used for the fast spin-echo sequence partially accounts for the difference in detection of implant ruptures in this study.

22. 高速 spin-echo MR 画像における解像特性(MR-高速 SE)

22. 高速 spin-echo MR 画像における解像特性(MR-高速 SE)

Fast spin-echo MR images of the pelvis obtained with a phased-array coil: value in localizing and staging prostatic carcinoma.

The fast spin-echo pulse sequence allows T2-weighted MR images to be acquired more rapidly than is possible with conventional spin-echo sequences, and phased-array coils can provide a higher signal-to-noise ratio than is possible with the body coil. The combination of these methods permits higher resolution images to be obtained with more signal averages despite shorter imaging times. In this study, initial technical comparisons designed to confirm the advantage of combining fast spin-echo pulse sequences with a pelvic phased-array multicoil were followed by an assessment of the value of these methods for the localization and staging of prostatic carcinoma. Seventy-one men with known (60) or suspected (11) prostatic carcinoma were imaged with T2-weighted fast spin-echo pulse sequences in the axial and coronal planes with a phased array of four surface coils (multicoil) for signal reception. Four of these men also were imaged with fast spin-echo sequences and the body coil, and six of these men also were imaged with T2-weighted conventional spin echo sequences and the multicoil; image qualities achieved with these techniques were compared. The use of IV glucagon (42 of 71 studies) before fast spin-echo sequences was correlated with the subsequent presence or absence of peristaltic artifacts on MR images. MR images were analyzed for the presence or absence of prostatic cancer in the right and left sides of the gland and for evidence of spread either through the capsule, into the seminal vesicles, or to lymph nodes or bone. Findings at MR imaging were compared with results of radical prostatectomy (20), lymph node dissection without prostatectomy (seven), and biopsy (67). Image quality obtained with the combination of the fast spin-echo sequence with the multicoil was judged superior to that obtained with either the conventional spin-echo sequence with the multicoil or the fast spin-echo sequence with the body coil. Significant motion artifacts were noted in 45% of studies (13/29) performed without glucagon vs 7% of studies (3/42) performed with glucagon. In the 58 patients for whom information concerning the location of tumor in either the right or left side of the gland was obtained from biopsy (39) or surgery (19), MR images allowed cancer to be detected with 89% sensitivity and 77% specificity. Among the 20 patients undergoing prostatectomy and seven others undergoing lymph node dissection, MR imaging permitted high accuracies in predicting involvement of the seminal vesicles (100%), local transcapsular spread (85%), and involvement of pelvic lymph nodes (85%). Fast spin-echo imaging with a pelvic phased-array multicoil provides high-resolution images of the prostate that may obviate an endorectal coil for the detection, localization, and staging of prostatic carcinoma.

Normal anatomy of the hippocampus and adjacent temporal lobe: high-resolution fast spin-echo MR images in volunteers correlated with cadaveric histologic sections.

This essay illustrates the appearances of sections of the normal hippocampus and adjacent temporal lobe on high-resolution heavily T2-weighted fast spin-echo MR images and correlates them with histologic sections. We found that this MR examination showed the detailed anatomy of the normal hippocampus in a much shorter time than is possible with conventional spin-echo techniques. The information provided in this essay can be used as a baseline for distinguishing between normal and abnormal hippocampi in a variety of disease states.

Fast spin-echo high-resolution MR imaging of the inner ear.

Advances in MR imaging continue to improve our ability to evaluate temporal bone anatomy and disease. CT remains the procedure of choice for fine-detail imaging of bone structures such as ossicular anatomy, but it is not the ideal imaging technique for soft-tissue structures (e.g., the membranous labyrinth and neural structures). Conventional spin-echo MR techniques used to image these structures cannot yield excellent contrast and spatial resolution in clinically acceptable time frames. Conventional spin-echo T1-weighted images lack tissue contrast between fluid (e.g., CSF, endolymph, perilymph), neural tissue, otic capsule septa, and surrounding temporal bone. Conventional T2-weighted imaging of the inner ear is needed to reveal the natural contrast between fluid, neural structures, and bone; unfortunately, the use of conventional T2-weighted images is limited by time constraints when large-matrix, thin-section techniques with more than one excitation are used. Fast spin-echo imaging is a recently developed technique that can provide T2-weighted, thin-section (2-mm) high-resolution images with excellent contrast in a fraction of the time needed for conventional spin-echo techniques. This speed advantage allows us to obtain high-resolution images in clinically acceptable time frames. Images produced by this technique are a useful addition, in conjunction with routine T1- and T2-weighted spin-echo images, in the diagnosis of disorders of the inner ear.

Fast spin-echo MR imaging of the brain and spine: current concepts.

Fast spin-echo MR imaging of the brain and spine: current concepts.K M Jones, R V Mulkern, R B Schwartz, K Oshio, P D Barnes and F A JoleszAudio Available | Share

EFFECT OF CLOFIBRATE AND ANDROSTERONE ON HYPERCHOLESTEROLAEMIC XANTHOMATOSIS.

The recent introduction of simultaneous whole-body PET/MR scanners has enabled new research taking advantage of the complementary information obtainable with PET and MRI. One such application is kinetic modeling, which requires high levels of PET quantitative stability. To accomplish the required PET stability levels, the PET subsystem must be sufficiently isolated from the effects of MR activity. Performance measurements have previously been published, demonstrating sufficient PET stability in the presence of MR pulsing for typical clinical use; however, PET stability during radiofrequency (RF)-intensive and gradient-intensive sequences has not previously been evaluated for a clinical whole-body scanner. In this work, PET stability of the GE SIGNA PET/MR was examined during simultaneous scanning of aggressive MR pulse sequences. <b>Methods:</b> PET performance tests were acquired with MR idle and during simultaneous MR pulsing. Recent system improvements mitigating RF interference and gain variation were used. A fast recovery fast spin echo MR sequence was selected for high RF power, and an echo planar imaging sequence was selected for its high heat-inducing gradients. Measurements were performed to determine PET stability under varying MR conditions using the following metrics: sensitivity, scatter fraction, contrast recovery, uniformity, count rate performance, and image quantitation. A final PET quantitative stability assessment for simultaneous PET scanning during functional MRI studies was performed with a spiral in-and-out gradient echo sequence. <b>Results:</b> Quantitation stability of a ⁶⁸Ge flood phantom was demonstrated within 0.34%. Normalized sensitivity was stable during simultaneous scanning within 0.3%. Scatter fraction measured with a ⁶⁸Ge line source in the scatter phantom was stable within the range of 40.4%–40.6%. Contrast recovery and uniformity were comparable for PET images acquired simultaneously with multiple MR conditions. Peak noise equivalent count rate was 224 kcps at an effective activity concentration of 18.6 kBq/mL, and the count rate curves and scatter fraction curve were consistent for the alternating MR pulsing states. A final test demonstrated quantitative stability during a spiral functional MRI sequence. <b>Conclusion:</b> PET stability metrics demonstrated that PET quantitation was not affected during simultaneous aggressive MRI. This stability enables demanding applications such as kinetic modeling.