Biomedical subjects
Publications and source records attributed to N M Rofsky.
Imaging evaluation is important in the follow-up of patients who have undergone surgical repair of the aorta. We present a case in which MR imaging demonstrated compression of the superior vena cava (SVC) as a late complication of ascending aortic aneurysm surgery. This complication led to thrombosis and clinical SVC syndrome.
PURPOSE: Our goal was to compare in-phase (IP) and opposed-phase (OP) sequences for GRE breath-hold hepatic imaging. METHOD: Non-contrast-enhanced IP and OP GRE breath-hold images were obtained in 104 consecutive patients referred for abdominal MRI at 1.0 T. For both sequences, the TR, FA, matrix, FOV, slice thickness, interslice gap, and measurements were kept constant. Images were compared quantitatively [liver/spleen and liver/lesion signal difference/noise ratio, (SD/N)] and qualitatively (artifacts, lesion detection and conspicuity, and intrahepatic anatomy). RESULTS: There was no statistically significant difference when comparing IP and OP sequences for liver/spleen and liver/lesion SD/N or for the qualitative parameters. In patients with fatty infiltration, the OP sequences yielded substantially lower values for liver/spleen and liver/lesion SD/N (0.9 and -1.2, respectively) than the IP sequences (20 and 17, respectively). Furthermore, in several cases with fatty infiltration, many more lesions were identified using IP images. CONCLUSION: The use of IP and OP GRE sequences provides complementary diagnostic information. Focal liver lesions may be obscured in the setting of fatty infiltration if only OP sequences are employed. A complete assessment of the liver with MR should include both IP and OP imaging.
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PURPOSE: Our purpose was to assess the efficacy of MR-guided biopsies with a conventional superconducting MR scanner and describe the techniques used to achieve successful results. METHOD: Fourteen biopsies were completed under MR guidance in 11 patients. Seven patients with previously detected lesions were referred for biopsy under MR guidance when hepatic lesions were identified by MRI but not with prebiopsy noncontrast CT or ultrasound (US). Additionally referred for MR-guided biopsy were four patients in whom previous CT- or US-guided biopsies of focal lesions were nondiagnostic. A 22 gauge MR-compatible needle was used in each case. Lesions ranged in size from 8 to 32 mm. Eleven lesions (eight patients) were suspected of being hepatomas, and three lesions (three patients) were suspected of being metastases. RESULTS: Thirteen of 14 MR-guided biopsies (93%) were diagnostic. Hepatocellular carcinoma was confirmed in 6 of 11 lesions suspected of representing hepatoma. One lesion, in a patient treated with chemoembolization, demonstrated necrotic material. One lesion yielded nondiagnostic material despite repeated visualization of the needle tip in the target lesion. Three lesions demonstrated metastatic carcinoma. Benign hepatocytes were detected in three biopsy specimens. Seven of the lesions that were successfully biopsied measured < 2.5 cm in diameter. CONCLUSION: With use of a closed bore 1.5 T system, diagnostic MR-guided needle aspiration biopsies of hepatic masses and subcomponents, including small lesions (< 2.5 cm), can be successfully obtained.
PURPOSE: Our purpose was to determine the effects of apnea during end-inspiration compared with free breathing on timing examinations performed to optimize gadolinium-enhanced 3D MR angiography (MRA) of the thoracic aorta and arch vessels. METHOD: Thirty patients referred for gadolinium-enhanced 3D MRA of the thoracic aorta and branch vessels underwent two timing examinations: one performed during free breathing and one during apnea at end-inspiration to replicate more closely the respiratory pattern used to obtain 3D MRA. For each, axial images at the level of the proximal neck were acquired every 2 s for 40 s, during which time 1 ml of gadolinium contrast agent followed by 20 ml of saline was infused at 2 ml/s. The time to peak arterial enhancement (Ta), time to first jugular venous enhancement (Tj), and arterio-venous window (time from peak arterial enhancement to first jugular venous enhancement; AV) were compared for the two examinations in each patient. RESULTS: Overall there was no statistically significant difference in Ta, Tj, or AV between examinations performed during free breathing and apnea in end-inspiration, although a trend to delayed circulation times was observed with apnea (p = 0.2-0.3). In five patients (17%), the difference in Ta between free breathing and apnea was 4 s; in three patients (10%), the difference was 6 s. CONCLUSION: Circulation times determined during apnea at end-inspiration may differ from those obtained during free breathing by as much as 6 s in an individual patient. This difference may account for inappropriately timed gadolinium-enhanced MR angiograms performed with timing examinations, especially when very short acquisition times and low doses of gadolinium (20 ml) are used.
We describe a case of a surgically proven intraosseous venous anomaly of the fibula in a patient who presented with ankle pain and swelling with deep venous thrombosis. MRI, including gadolinium-enhanced MR angiography, provides a less invasive means than conventional venography for diagnosing these lesions and assessing venous patency while also allowing for evaluation of extravascular structures.
PURPOSE: The purpose of this work was to determine the sensitivity of hepatic digital subtraction arteriography (DSA) for the detection of hepatocellular carcinoma (HCC) and dysplastic nodules (DNs) when compared with pathological findings from whole liver explants. METHOD: Twenty-one patients 30-72 years old (mean 54 years) with cirrhosis and known or clinically suspected HCC (20 prior to chemoembolization) underwent hepatic DSA with subsequent transplantation within 80 days (mean 32 days). The prospective DSA report was compared with pathologic findings from explanted livers. RESULTS: Overall, DSA detected 31 of 95 HCC lesions for a sensitivity of 33%. Of these 31 lesions, 28 were hypervascular and 3 were hypovascular. DSA detected all six HCCs measuring >5 cm, all six HCCs measuring 3-5 cm, and all five HCCs 2-3 cm, resulting in a sensitivity of 100% (17/17) for HCC >2 cm. DSA detected 7 of 18 HCCs measuring 1-2 cm (sensitivity 39%) and 7 of 60 HCCs < or =1 cm (sensitivity 12%). Overall sensitivity for DSA in detection of HCC < or =2 cm was 18% (14/78 lesions). None of 17 DNs (0.2-1.5 cm in size) was identified on DSA. CONCLUSION: DSA is insensitive to small HCC (< or =2 cm), carcinomatosis arising within nodules, and DN.
OBJECTIVE: To determine if iron containing "siderotic" nodules detected at magnetic resonance (MR) imaging are regenerative (RN) or dysplastic (DN) and to attempt to identify features that may distinguish them. MATERIAL AND METHODS: MR imaging (1.5 T) was performed on 77 cirrhotic patients who underwent orthotopic liver transplantation within 0-117 days (mean 30 days) of MR imaging. Two readers retrospectively evaluated breath-hold gradient-echo pulse sequences (echo time > or =9.0 ms, flip angle < or =45 degrees) for the presence of hypointense nodules, which were classified as micronodular (< or =3 mm), macronodular (>3 mm), or mixed. Nodule distribution was classified as focal (<5), scattered (5-20), or diffuse (>20) per slice. Thin section pathologic correlation was available in all cases, and Prussian blue iron stains were performed. RESULTS: Of 35 patients with pathologically proven siderotic nodules, 10 (29%) had at least 2 siderotic DN. MR detected siderotic nodules in 10 of 10 (100%) patients with siderotic DN and RN, and in 18 of 25 patients (72%) with siderotic RN only. CONCLUSION: Siderotic RN cannot be reliably distinguished from siderotic DN with MR imaging, and therefore the widely used term "siderotic regenerative nodule" should be avoided and replaced by "siderotic nodule."
Retroperitoneal fat necrosis is a well-known complication of acute pancreatitis. We describe an unusual case of fat necrosis presenting as multiple, bilateral renal pseudotumors in a patient with acute pancreatitis. The imaging findings on CT and MR are discussed.