Biomedical subjects
Publications and source records attributed to Vamsidhar R Narra.
OBJECTIVE: Our objective was to detail peritoneal anatomy, techniques for optimizing peritoneal MRI, and the MRI characteristics of several disease processes that frequently involve the peritoneum. CONCLUSION: Homogeneous fat suppression and dynamic contrast-enhanced imaging, including delayed imaging, are critical technical factors for successful lesion detection and characterization on peritoneal MRI.
PURPOSE: To prospectively determine the safety and efficacy of the gadolinium-based blood pool magnetic resonance (MR) imaging contrast agent gadofosveset in patients known to have or suspected of having peripheral vascular disease. MATERIALS AND METHODS: Ethical committee approval and patient written informed consent were obtained. This study was compliant with the Health Insurance Portability and Accountability Act. Adults known or suspected to have peripheral vascular disease received gadofosveset (0.03 mmol per kilogram of body weight) for MR angiography of the aortoiliac region. Gadofosveset-enhanced MR angiography and unenhanced two-dimensional time-of-flight MR angiography were compared with the reference standard, conventional angiography, for the presence of vascular stenosis. All patients were monitored for adverse events with hematologic analysis, analysis of blood chemistry, urinalysis, and electrocardiographic parameters; these methods were analyzed to determine safety. RESULTS: A total of 274 patients were enrolled at 37 centers. Gadofosveset-enhanced MR angiography showed significant improvement (P < .001) compared with unenhanced MR angiography for each of the readers for diagnosis of clinically significant (> or = 50%) stenosis. Specificity and accuracy were significantly greater for three readers, and sensitivity increased significantly for two readers. For all readers, the area under the receiver operator characteristic curve for both quantitative and qualitative measures of significant disease increased (P < .001) for gadofosveset-enhanced MR angiography versus two-dimensional time-of-flight MR angiography. All readers also expressed more confidence in diagnosis (P < .001) and found fewer images to be uninterpretable (0.5% vs 11.0%). The most common adverse events were as follows: feeling hot, 12 (4.4%) patients; nausea, 10 (3.6%) patients; headache, nine (3.3%) patients; and burning sensation, eight (2.9%) patients. Only four serious adverse events were reported, in three patients, and all events were rated as unlikely related to the drug. No patients were excluded because of adverse events or laboratory abnormalities. There were no clinically important trends in the findings of hematologic analysis, blood chemistry, urinalysis, electrocardiography, or physical examination. CONCLUSION: On the basis of substantial improvements over non-contrast MR angiography in efficacy and a minimal and transient side-effect profile, gadofosveset was found to be safe and effective for MR angiography in patients known or suspected to have peripheral vascular disease.
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A case report of a 40-year-old female with an unusually small pheochromocytoma of the organ of Zuckerkandl is discussed. The tumor is diagnosed by magnetic resonance imaging MRI examination, which was requested to evaluate her as a potential renal donor. There is a family history of Carney s triad gastric leiomyosarcoma, extra-adrenal pheochromocytoma and pulmonary chondroma. The MRI technique and findings are discussed.
Because of the enormous economic and social impact of cardiovascular disease in the United States there is a need for improved noninvasive diagnosis. Cardiac MR imaging isa versatile, comprehensive technique for assessing cardiac morphology and function. With an understanding of cardiac anatomy and physiology and MR imaging physical principles,cardiac MR imaging can be performed and can play an important role in patient management. This article provides the reader with a basic understanding of cardiac MR imaging and the practical applications required to perform cardiac MR imaging.
The detection of adrenal lesions has increased with the expanding use of cross-sectional imaging. Magnetic resonance (MR) imaging is often useful for characterizing adrenal masses. Adrenal masses can be classified into various groups on the basis of the presence of intracellular lipid, macroscopic fat, hemorrhage, and cystic changes and the vascularity and shape of the tumor. These imaging features can be used by the radiologist to suggest or confirm a diagnosis for most adrenal masses, including adenoma, hyperplasia, simple and complicated cysts, lymphangioma, myelolipoma, pheochromocytoma, hemorrhage, cortical carcinoma, neuroblastoma, lymphoma, and metastases. Adenomas and metastases are common, and a decrease in signal intensity on out-of-phase images can be used to differentiate between them. Carcinoma is a possible diagnosis if that decrease in signal intensity is heterogeneous. Benign disease is diagnosed if macroscopic fat or a homogeneous cystlike lesion is seen. Recognition of the typical MR imaging features is important because it often changes the treatment approach and may obviate surgery.
Because of the enormous economic and social impact of cardiovascular disease in the United States, there is a need for improved noninvasive diagnosis. Cardiac MR imaging is a versatile, comprehensive technique for assessing cardiac morphology and function. With an understanding of cardiac anatomy and physiology as well as MR physical principles, cardiac MR imaging can be performed and play an important role in patient management.
In 15 volunteers and 84 patients with clinically suspected peripheral vascular disease, a stepping kinematic imaging platform, a manual retrofit stepping magnetic resonance (MR) imaging table, was used with three high-field-strength MR imaging systems to perform multistation peripheral contrast material-enhanced MR angiography in the lower extremity with the existing system phased-array coil. Each examination was performed in less than 45 minutes. Mounting of the stepping kinematic imaging platform was quick and simple and allowed rapid repositioning of a patient relative to the phased-array coil and acquisition of high-spatial-resolution MR angiograms of the peripheral vasculature with use of one injection of MR imaging contrast agent.
Magnetic resonance (MR) imaging has considerable potential in characterizing pancreatic masses. Certain features can be used by the radiologist to establish a definitive diagnosis for most pancreatic tumors including ductal adenocarcinoma, islet cell tumors, solid and papillary epithelial neoplasms, micro- and macrocystic adenoma, and metastases. Recognition of these tumors on imaging is important since it often changes the treatment approach and may obviate the need for surgery. Recent introduction of 3D gradient recalled echo (GRE) sequence such as volumetric interpolated breath hold examination (VIBE) has dramatically improved MR imaging by providing dynamic enhanced thin-slice images with fat saturation and high signal-to-noise ratio. In this article, special emphasis will be placed on the impact of 3D GRE sequence in the diagnosis of pancreatic neoplasms with pathologic correlation.
Primary sclerosing cholangitis is a progressive cholestatic disease of unknown etiology leading to cirrhosis and liver failure. Several imaging modalities have been used to study this disease, including ultrasonography, computed tomography and hepatobiliary scintigraphy, but accurate diagnosis was found to be best made with endoscopic retrograde cholangiopancreatography or direct cholangiography. However, these 2 methods are invasive and may produce serious complications. Magnetic resonance cholangiopancreatography is a noninvasive imaging technique that has become very useful for diagnosing primary sclerosing cholangitis. Contrast enhanced magnetic resonance imaging provides pertinent information of extraductal abnormalities in addition to biliary ductal changes.
Angiomyolipoma is a benign mesenchymal neoplasm that typically occurs in the kidney sporadically or in patients with tuberous sclerosis complex. Extrarenal angiomyolipomas are uncommon, and the liver is the most common extrarenal site. Other sites reported include the bone, colon, heart, lung, parotid gland, skin, spermatic cord, gynecologic regions, and retroperitoneum. A case of an angiomyolipoma involving the right adrenal gland in a 49-year-old female patient with tuberous sclerosis is reported. The magnetic resonance (MR) imaging features are also discussed. Only 2 cases describing adrenal angiomyolipoma were found in the English literature. Neither of these 2 cases was documented in the radiology literature or discussed the MR features of adrenal angiomyolipoma.
Magnetic resonance imaging (MRI) is playing an important role in the clinical evaluation of women presenting with urethral symptoms. Voiding cystourethrography, direct urethrography, and pelvic sonography provide limited information on abnormalities that are in continuity with the urethra. On the other hand, urethra and periurethral tissues can be noninvasively evaluated by high-resolution endocavitary MRI. Because of its multiplanar capability and high tissue contrast, endovaginal MRI is an extremely reliable diagnostic test in the evaluation of urethral abnormalities. In this article, the utility of endovaginal MRI in the detection and characterization of a wide spectrum of urethral pathologic conditions, such as congenital anomalies, diverticula, urethritis, and benign and malignant neoplasms, is discussed.
The spleen has the same relationship to the circulatory system that the lymph nodes have to the lymphatic system. A wide range of diseases can affect the spleen. Pathologic conditions of the spleen can be classified into the following categories: congenital diseases (accessory spleen, polysplenia, and asplenia); trauma; inflammation (abscess, candidiasis, histoplasmosis, and sarcoidosis); vascular disorders (infarction, diseases affecting the splenic vasculature, and arteriovenous malformation); hematologic disorders (sickle cell disease and extramedullary hematopoiesis); benign tumors (cysts, hemangioma, diffuse hemangiomatosis of the spleen, and hamartoma); malignant tumors (sarcoma, lymphoma, and metastases); and other disease processes that affect the spleen diffusely (portal hypertension, Gaucher disease, and sickle cell disease) or focally (Gamna-Gandy nodules). New magnetic resonance (MR) imaging techniques have increased the role of MR imaging in detection and characterization of splenic diseases. MR imaging is an excellent tool for diagnosis and evaluation of focal lesions and pathologic conditions of the spleen.
Focal hepatic lesions constitute a daily challenge in the clinical setting. However, noninvasive methods can be useful in the detection and characterization of these lesions. The noninvasive diagnosis of liver lesions is usually achieved with contrast material-enhanced computed tomography and magnetic resonance (MR) imaging. Dynamic three-dimensional gradient-recalled-echo MR imaging provides dynamic contrast-enhanced thin-section images with fat saturation and a high signal-to-noise ratio and is excellent for the evaluation of various focal hepatic lesions. A comprehensive MR imaging examination in this setting includes T2-weighted and chemical shift T1-weighted imaging and demonstrates characteristic enhancement patterns that can be helpful in the diagnosis of most of these lesions. These enhancement patterns are seen during particular phases of contrast-enhanced imaging and include arterial phase enhancement, delayed phase enhancement, peripheral washout, ring enhancement, nodule-within-a-nodule enhancement, true central scar, pseudocentral scar, and pseudocapsule. Familiarity with these enhancement patterns can help in the identification of specific focal lesions of the liver.