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Fat Suppression (fat + suppression)
Selected AbstractsFat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: A dual STIR-CHESS combination prepulse for turbo spin echo pulse sequencesJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2010Koji Tanabe DDS Abstract Purpose: To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). Materials and Methods: To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl2 aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl2 aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Results: Dual-FS could suppress fat sufficiently within the inversion time of 110,140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. Conclusion: The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. J. Magn. Reson. Imaging 2010;31:1277,1281. ©2010 Wiley-Liss, Inc. [source] Diagnosis of pancreatic cancerHPB, Issue 5 2006Fumihiko Miura Abstract The ability to diagnose pancreatic carcinoma has been rapidly improving with the recent advances in diagnostic techniques such as contrast-enhanced Doppler ultrasound (US), helical computed tomography (CT), enhanced magnetic resonance imaging (MRI), and endoscopic US (EUS). Each technique has advantages and limitations, making the selection of the proper diagnostic technique, in terms of purpose and characteristics, especially important. Abdominal US is the modality often used first to identify a cause of abdominal pain or jaundice, while the accuracy of conventional US for diagnosing pancreatic tumors is only 50,70%. CT is the most widely used imaging examination for the detection and staging of pancreatic carcinoma. Pancreatic adenocarcinoma is generally depicted as a hypoattenuating area on contrast-enhanced CT. The reported sensitivity of helical CT in revealing pancreatic carcinoma is high, ranging between 89% and 97%. Multi-detector-row (MD) CT may offer an improvement in the early detection and accurate staging of pancreatic carcinoma. It should be taken into consideration that some pancreatic adenocarcinomas are depicted as isoattenuating and that pancreatitis accompanied by pancreatic adenocarcinoma might occasionally result in the overestimation of staging. T1-weighted spin-echo images with fat suppression and dynamic gradient-echo MR images enhanced with gadolinium have been reported to be superior to helical CT for detecting small lesions. However, chronic pancreatitis and pancreatic carcinoma are not distinguished on the basis of degree and time of enhancement on dynamic gadolinium-enhanced MRI. EUS is superior to spiral CT and MRI in the detection of small tumors, and can also localize lymph node metastases or vascular tumor infiltration with high sensitivity. EUS-guided fine-needle aspiration biopsy is a safe and highly accurate method for tissue diagnosis of patients with suspected pancreatic carcinoma. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been suggested as a promising modality for noninvasive differentiation between benign and malignant lesions. Previous studies reported the sensitivity and specificity of FDG-PET for detecting malignant pancreatic tumors as being 71,100% and 64,90%, respectively. FDG-PET does not replace, but is complementary to morphologic imaging, and therefore, in doubtful cases, the method must be combined with other imaging modalities. [source] Gadolinium-enhanced magnetic resonance imaging.INFLAMMATORY BOWEL DISEASES, Issue 2 2004A useful radiological tool in diagnosing pediatric IBD Abstract Background Recent advances in gadolinium-enhanced magnetic resonance imaging (G-MRI) have been developed to enhance the resolution of the intestinal mucosa and facilitate the differentiation of ulcerative colitis (UC) from Crohn's disease (CD). The objective of this study is to apply this technology in Pediatrics. Methods A G-MRI was performed on 58 consecutive children with suspected IBD between 1999 and 2002 using intravenous gadolinium, fat suppression, and respiration-suspended sequences to enhance the resolution of the intestinal wall. The sensitivity and specificity in diagnosing either UC or CD was determined by comparing the G-MRI to the established histologic diagnosis. Results G-MRI confirmed the diagnosis of either CD (21) or UC (7) with a sensitivity and specificity of 96% and 92%, respectively. Among the 21 patients with CD, 14 showed proximal small bowel involvement by G-MRI. In total, 17 patients were diagnosed with indeterminate colitis (IC) based on histologic criteria alone, and among these patients, G-MRI had a significantly lower non-classification rate (P < 0.02). In comparison, endoscopy was less sensitive (57%), but more specific (100%) than either histology or G-MRI in diagnosing IBD. G-MRI also showed a strong concordance with computed tomography in diagnosing CD (P = 0.001). Conclusion G-MRI is a both a sensitive and specific radiologic tool in diagnosing pediatric IBD. In patients with CD, G-MRI may be useful in identifying proximal small bowel involvement. Longitudinal follow-up studies are needed in those patients diagnosed with IC to determine the predictive value of G-MRI testing. [source] Pain related to rotator cuff abnormalities: MRI findings without clinical significanceJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2010Jenny T. Bencardino MD Abstract MRI has become an important diagnostic tool in the evaluation of rotator cuff pathology and the technology continues to evolve. Direct MR arthrography, diagnosis-specific sequencing such as fat suppression, special positioning such as abducted externally rotated (ABER) views and ultra high field magnets allow for an unprecedented level of detail in imaging. In this article, we review MRI findings in patients with rotator cuff abnormalities that are anatomic variants or incidental findings. Although MRI findings may be diagnostic in some cases, we find that clinical correlation with history and physical examination is critical to differentiate between anatomic variants, incidental findings, and true pathology. We conclude that good communication between the orthopedic surgeon and the radiologist is necessary to optimize diagnostic yield. J. Magn. Reson. Imaging 2010;31:1286,1299. © 2010 Wiley-Liss, Inc. [source] Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: A dual STIR-CHESS combination prepulse for turbo spin echo pulse sequencesJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2010Koji Tanabe DDS Abstract Purpose: To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). Materials and Methods: To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl2 aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl2 aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Results: Dual-FS could suppress fat sufficiently within the inversion time of 110,140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. Conclusion: The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. J. Magn. Reson. Imaging 2010;31:1277,1281. ©2010 Wiley-Liss, Inc. [source] Fast spin-echo triple-echo Dixon: Initial clinical experience with a novel pulse sequence for fat-suppressed T2-weighted abdominal MR imagingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2009Russell N. Low MD Abstract Purpose To evaluate a prototype fast spin echo (FSE) triple-echo-Dixon (fTED) technique for breath-hold, fat-suppressed, T2-weighted abdominal imaging. Materials and Methods Forty patients underwent breath-hold T2-weighted abdominal imaging with fTED and conventional fast recovery (FR) FSE with chemical shift-selective saturation (CHESS). FRFSE and fTED images were compared for overall image quality, homogeneity of fat suppression, image sharpness, anatomic detail, and phase artifact. Depiction of disease was recorded separately for FRFSE and fTED images. Results FTED successfully reconstructed water-only and fat-only images from source images in all 40 cases. Water and fat separation was perfect in 36 (0.90) patients. Homogeneity of fat suppression was superior on the fTED images in 38 (0.95) of 40 cases. FTED images showed better anatomic detail in 27 (0.68), and less susceptibility artifact in 20 (0.50). FRFSE images showed less vascular pulsation artifact in 30 (0.75) cases, and less phase artifact in 21 (0.53) cases. There was no difference in depiction of disease for FRFSE and fTED images. Conclusion FTED is a robust sequence providing breath-hold T2-weighted images with superior fat suppression, excellent image quality, and at least equal depiction of disease compared to conventional breath-hold T2-weighted FRFSE imaging. J. Magn. Reson. Imaging 2009;30:569,577. © 2009 Wiley-Liss, Inc. [source] Echo combination to reduce proton resonance frequency (PRF) thermometry errors from fatJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2008Viola Rieke PhD Abstract Purpose To validate echo combination as a means to reduce errors caused by fat in temperature measurements with the proton resonance frequency (PRF) shift method. Materials and Methods Computer simulations were performed to study the behavior of temperature measurement errors introduced by fat as a function of echo time. Error reduction by combining temperature images acquired at different echo times was investigated. For experimental verification, three echoes were acquired in a refocused gradient echo acquisition. Temperature images were reconstructed with the PRF shift method for the three echoes and then combined in a weighted average. Temperature measurement errors in the combined image and the individual echoes were compared for pure water and different fractions of fat in a computer simulation and for a phantom containing a homogenous mixture with 20% fat in an MR experiment. Results In both simulation and MR measurement, the presence of fat caused severe temperature underestimation or overestimation in the individual echoes. The errors were substantially reduced after echo combination. Residual errors were about 0.3°C for 10% fat and 1°C for 20% fat. Conclusion Echo combination substantially reduces temperature measurement errors caused by small fractions of fat. This technique then eliminates the need for fat suppression in tissues such as the liver. J. Magn. Reson. Imaging 2007. © 2007 Wiley-Liss, Inc. [source] Simultaneous myocardial and fat suppression in magnetic resonance myocardial delayed enhancement imaging,JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007Thomas K.F. Foo PhD Abstract Purpose To develop a method for fat suppression in myocardial delayed enhancement (MDE) studies that achieves effective signal intensity reduction in fat but does not perturb myocardial signal suppression. Materials and Methods A new approach to fat suppression that uses a spectrally-selective inversion-recovery (SPEC-IR) tip-up radio frequency (RF) pulse following the conventional nonselective IR RF pulse together with a second SPEC-IR RF pulse is proposed. The tip-up pulse restores the fat longitudinal magnetization after the nonselective IR pulse and allows the fat magnetization to recover more fully toward its equilibrium value, providing for better fat suppression by the second SPEC-IR RF pulse. This new approach was validated in phantom studies and in five patients. Results Effective fat suppression was achieved using the proposed technique with minimal impact on normal myocardial signal suppression. Mean fat suppression achieved using this approach was 67% ± 8%, as measured in the chest wall immediately opposite the heart. Conclusion The results indicate this modular-type approach optimizes fat suppression in myocardial delayed enhancement studies but does not perturb the basic IR pulse sequence or change basic acquisition parameters. J. Magn. Reson. Imaging 2007;26:927,933. © 2007 Wiley-Liss, Inc. [source] Reproducibility and dependence on diffusion weighting of line scan diffusion in the lumbar intervertebral discsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2005David C. Newitt PhD Abstract Purpose To investigate the dependence of line scan diffusion imaging (LSDI) in the lumbar vertebral discs on diffusion weighting, fat suppression (FS), and postprocessing noise correction. Materials and Methods Eleven normal volunteers were scanned using 4 b-value and 12 b-value LSDI protocols, with and without FS. Three repeated four b-value scans were performed for evaluation of the reproducibility of apparent diffusion coefficient (ADC) values calculated with mono- and biexponential decay models. Two-point ADC analysis for 12 b-value scans was performed with and without noise correction to evaluate the ADC dependence on diffusion weighting. Correlations between different ADC calculation and acquisition methods were evaluated. Results Monoexponential ADC measures had a coefficient of variation (CV) under 3%, while use of a constrained biexponential increased the CV to 6% to 9%. Strong dependence on b-value was seen from chemically shifted marrow fat signal and noise. These systematic variations in ADC were eliminated using noise correction and FS. ADC values from 4 and 12 b-value FS scans correlated strongly (R2 = 0.91), while biexponentially derived ADC values correlated moderately well with the FS ADC (R2 = 0.51). Conclusion LSDI gives reproducible ADC measurements in the lumbar discs, largely independent of b-value and signal-to-noise ratio (SNR) when used with noise correction and FS. J. Magn. Reson. Imaging 2005;21:482,488. © 2005 Wiley-Liss, Inc. [source] Keyhole Dixon method for faster, perceptually equivalent fat suppressionJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2003Chris A. Flask MS Abstract Purpose To reduce the acquisition time associated with the two-point Dixon fat suppression technique by combining a keyhole in-phase (Water + Fat) k-space data set with a full out-of-phase (Water , Fat) k-space data set and optimizing the keyhole size with a perceptual difference model. Materials and Methods A set of keyhole Dixon images was created by varying the number of lines in the keyhole data set. Off-resonance correction was incorporated into the image reconstruction process to improve the homogeneity of the fat suppression. A perceptual difference model (PDM) was validated with human observer experiments and used to compare the keyhole images to images from a full two-point Dixon acquisition. The PDM was used to determine the smallest keyhole width required to obtain perceptual equivalence to images obtained from the full two-point Dixon method. Results In experimental phantom studies, the keyhole Dixon image reconstructed from 96 of 192 Water + Fat k-space lines and 192 Water , Fat k-space lines was perceptually equivalent to the full (192 + 192) two-point Dixon images, resulting in a 25% reduction in scan time. Clinical images of a volunteer's knee, orbits, and abdomen created from the smallest, perceptually equivalent keyhole width resulted in a 27%,38% reduction in total scan time. Conclusion This method improves the temporal efficiency of the conventional two-point Dixon technique and may prove especially useful for high-field systems where specific absorption rate (SAR) limits will constrain radiofrequency (RF)-based fat suppression techniques. J. Magn. Reson. Imaging 2003;18:103,112. © 2003 Wiley-Liss, Inc. [source] Comparison of fat suppression strategies in 3D spiral coronary magnetic resonance angiographyJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2002Peter Börnert PhD Abstract Purpose In the present study, the impact of the two different fat suppression techniques was investigated for free breathing 3D spiral coronary magnetic resonance angiography (MRA). As the coronary arteries are embedded in epicardial fat and are adjacent to myocardial tissue, magnetization preparation such as T2 -preparation and fat suppression is essential for coronary discrimination. Material and Methods Fat-signal suppression in three-dimensional (3D) thin- slab coronary MRA based on a spiral k-space data acquisition can either be achieved by signal pre-saturation using a spectrally selective inversion recovery pre-pulse or by spectral-spatial excitation. In the present study, the performance of the two different approaches was studied in healthy subjects. Results No significant objective or subjective difference was found between the two fat suppression approaches. Conclusion Spectral pre-saturation seems preferred for coronary MRA applications due to the ease of implementation and the shorter cardiac acquisition window. J. Magn. Reson. Imaging 2002;15:462,466. © 2002 Wiley-Liss, Inc. [source] | ||||||||||