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Biomedical subjects

Neil M Rofsky

Publications and source records attributed to Neil M Rofsky.

41 records · Page 3Linked to original sources

Magnetic resonance imaging for disorders of liver vasculature.

Magnetic resonance imaging (MRI) provides a noninvasive technique to evaluate the hepatic vasculature. Angiographic and flow-based techniques include intrinsic properties of MRI as well as those that use contrast media. Clinical and technical perspectives of a wide range of vascular disorders affecting the liver, particularly cirrhosis and portal hypertension, portal vein obstruction, as well as imaging of the vasculature prior to and postliver transplantation are presented in this article.

Adult↗

Two-station bolus-chase MR angiography with a stationary table: a simple alternative to automated-table techniques.

OBJECTIVE: Our purpose was to evaluate a simple, two-station, bolus-chase, peripheral MR angiography technique that relies on manual patient translation using a plastic patient-transfer board. SUBJECTS AND METHODS: Twenty patients successfully completed both lower extremity MR angiography and digital subtraction angiography within a 3-month period. For MR angiography, patients were placed on the scanner table on a standard plastic patient-transfer board. We performed unenhanced and contrast-enhanced imaging at the level of the pelvis using a three-dimensional gradient-echo sequence (TR range/TE range, 3.8-4.6/1.3-1.8; flip angle range, 25-40 degrees ). Then patients were quickly pulled 350-400 mm using the transfer-board handles, and two subsequent acquisitions were obtained at the level of the thighs. For each modality, two radiologists who were unaware of correlative imaging results retrospectively scored all vessel segments as either greater than or equal to 50% stenosis or less than 50% stenosis, and interobserver agreement was determined. Using digital subtraction angiography as the standard of reference, we used consensus data to compute MR angiography sensitivity and specificity. RESULTS: In the 261 vessel segments considered, MR angiography had a sensitivity of 75% (12/16) and a specificity of 98% (94/96) for the detection of stenosis greater than or equal to 50% from the aorta through the common femoral arteries. For the superficial and profunda femoral arteries through the popliteal arteries, these values were 97% (31/32) and 94% (34/36), respectively. MR angiography interobserver agreement for detection of stenosis was good (kappa = 0.68) for the aorta through the common femoral arteries and excellent (kappa = 0.88) for the superficial and profunda femoral arteries through the popliteal arteries. These values were comparable to those found for digital subtraction angiography (kappa = 0.67 and kappa = 0.88, respectively). CONCLUSION: Stationary-table MR angiography is a useful, simple strategy for lower extremity angiography in centers without a moving table.

Adult↗

Dynamic subtraction magnetic resonance imaging of cirrhotic liver: assessment of high signal intensity lesions on nonenhanced T1-weighted images.

PURPOSE: The purpose of this work was to determine the technical feasibility and value of dynamic subtraction (postcontrast-precontrast) magnetic resonance (MR) imaging for the assessment of hyperintense lesions on precontrast T1-weighted images in the cirrhotic liver. METHODS: One hundred four hyperintense lesions on T1-weighted precontrast and arterial phase postcontrast images were subjected to analysis of their subtraction qualities depending on the lesion size, location and/or the degree of misregistration between the source images in 27 different MR imaging sets. RESULTS: The quality of subtraction images was always diagnostic for lesions larger than 2 cm in diameter (n=8) but not diagnostic for 73% (40 of 55 lesions) of small subcentimetric lesions. Thirty-one subcapsular lesions always showed a variable degree of coregistration artifact. Only 3 of 35 lesions with a slice misregistration of 3 mm or more gave rise to subtraction images of diagnostic quality. For determining the contrast enhancement, the area under the receiver operating characteristic curve of 30 verified lesions was significantly larger (P <0.001) for subtraction images than for conventional arterial phase images. CONCLUSION: Depending on the lesion size and/or location or the degree of misregistration between the source images, dynamic subtraction MR imaging can be useful for the characterization of hyperintense lesions on precontrast T1-weighted imaging.

Adult↗

Magnetic resonance imaging findings in solitary fibrous tumor of the kidney.

The magnetic resonance imaging findings in a patient with a large solitary fibrous tumor (SFT) of the kidney originating in the renal capsule are presented. SFT of the kidney is a rare, usually benign tumor with indolent clinical behavior. MRI revealed a diffusely hypointense mass on T2-weighted images without central necrosis despite the large size of the lesion. These imaging features, atypical for renal cell carcinoma, can suggest the diagnosis of SFT and may be an indication for attempting nephron-sparing surgery.

Female↗

Three-dimensional, T1-weighted gradient-echo imaging of the brain with a volumetric interpolated examination.

BACKGROUND AND PURPOSE: T1-weighted, 3D gradient-echo MR sequences can be optimized for rapid acquisition and improved resolution through asymmetric k-space sampling and interpolation. We compared a volumetric interpolated brain examination (VIBE) sequence with a magnetization-prepared rapid acquisition gradient echo (MP RAGE) sequence and a 2D T1-weighted spin-echo (SE) sequence. METHODS: Thirty consecutive patients known or suspected to have focal brain lesions underwent postcontrast studies (20 mL of gadopentetate dimeglumine) with VIBE, MP RAGE, and 2D T1-weighted SE imaging. Source and 5-mm VIBE and MP RAGE reformations, and 5-mm T1-weighted SE images were compared qualitatively and by using signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). SNRs in a gadolinium-doped water phantom were also measured for all three sequences. RESULTS: On the source images, SNRs for gray matter (GM) and white matter (WM), and CNRs for WM-to-GM and contrast-enhancing lesion-to-GM were slightly, but significantly higher for the VIBE sequence than for the MP RAGE sequence (P <.05). On 5-mm reformations, WM-to-GM CNR was significantly higher on VIBE and MP RAGE images than on T1-weighted SE images (P <.001), but contrast-enhancing lesion-to-GM CNRs were higher on SE images compared with both gradient-echo sequences (P <.001). Qualitatively, VIBE images showed fewer flow artifacts than did SE and MP RAGE images (P <.05). In the phantom, VIBE SNR was higher than MP RAGE SNR for short T1 relaxation times. CONCLUSION: VIBE provides an effective, alternative approach to MP RAGE for fast 3D T1-weighted imaging of the brain.

Adult↗