CT, MR imaging, and radionuclide imaging in a patient with hepatic involvement in primary amyloidosis.
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Magnetic resonance imaging (MRI) was compared with radionuclide scintigraphy (RNS) in 16 patients with renal transplants undergoing renal failure to determine which modality could best discriminate between rejection, acute tubular necrosis (ATN), and cyclosporin nephrotoxicity (CN). Although all rejecting transplants had reduced corticomedullary differentiation (CMD) on T1-weighted MR images, four of five cases of ATN had appearances that could not be distinguished from rejection. A normal CMD suggests nonrejection, but diminished CMD is nonspecific. Tc-99m DTPA/I-131 hippuran RNS was superior to MRI in differentiating rejection from ATN. Although ATN and CN have similar RNS patterns, this distinction can usually be made based on the clinical time course. Other potential uses of MRI in the evaluation of the renal transplants are discussed.
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This report describes the nuclear cardiology procedures available for use as diagnostic techniques in patients with definite or suspected cardiovascular disease. The usefulness of myocardial imaging, radionuclide angiocardiography and other radionuclide cardiovascular imaging techniques is classified within specific disease states. The clinical utility of each technique is graded from I to IV, depending on the clinical importance of the technique (I = most important; IV = not indicated). A grade of V is given for methods now considered to be in their research phase. The usefulness of these methods is discussed in patients with acute ischemic heart disease, chronic ischemic heart disease, valvular heart disease, pulmonary vascular disease and hypertensive heart disease. Selected references are provided.
OBJECTIVES: Radionuclide imaging is a valuable tool during the early posttransplantation period for evaluating the functional status of renal and liver allografts. The aim of this study was to compare the early postoperative function of renal and liver allografts with serial radionuclide imaging. METHODS: Twenty-two renal and 22 liver allograft recipients were evaluated with serial radionuclide imaging. All grafts were from living related donors. For renal scintigraphy, recipients were injected with Tc-99m DTPA, and imaging was performed on postoperative days 3 and 7. Liver allograft recipients were evaluated with Tc-99m mebrofenin hepatobiliary scintigraphy within the first postoperative week and as required thereafter. The following parameters were computed for each scintigraphy: uptake, time to excretion of the radiopharmaceutical (T(ex)), and retention of radioactivity at the end of the study. RESULTS: Among 22 renal transplant recipients, 19 (86%) had normal uptake and T(ex) values on day 7 posttransplantation. Nine (41%) renal grafts exhibited retention. Among 22 liver transplant recipients, 7 (32%) had normal findings on the first hepatobiliary scan. All except eight liver grafts (64%) had a delay in T(ex), and 15 (68%) had parenchymal retention on the first scan, with improvement of function observed on serial scintigraphies obtained during follow-up. Decreases in uptake were seen less frequently and correlated with a prolonged postoperative hospital stay. CONCLUSION: Renal transplant recipients are more likely than liver allograft recipients to have a normal scintigraphy in the early posttransplantation period. Retention of radioactivity at the end of the study was the most frequently observed abnormality for both renal and liver allografts. Most liver transplant recipients exhibited a delay in excretion, and parenchymal retention, of radioactivity on the first evaluation, with subsequent improvement on follow-up serial scintigraphy studies.
The accuracy and reproducibility of cardiac ejection fraction (EF) measurements based on cine magnetic resonance (MR) imaging, radionuclide multigated acquisition (MUGA) blood pool imaging, and angiographic ventriculography were evaluated by comparing them with a volumetrically determined standard. A biventricular, compliant, fluid-filled heart phantom was developed to mimic normal cardiac anatomy and physiology. Ventricular EFs were measured with cine MR imaging by summation of nine contiguous 10-mm-thick sections in short and long axis, with single-plane ventriculography, and with MUGA. Three measurements were performed with each modality for each of three EFs. Ventriculography was least accurate, with average relative errors ranging from 7.9% for the largest EF to 60.1% for the smallest. Cine MR was most accurate, with average relative errors ranging from 4.4% to 8.5%. MUGA EF measurements showed good correlation, with average relative errors ranging from 7.1% to 22.4%. Comparison of the error variances for the three modalities with the F test revealed that MR and MUGA EF measurements were significantly more accurate than those based on ventriculography (P less than .01). No significant difference was demonstrated between the accuracy of short- and long-axis cine MR acquisitions.
This report describes the nuclear cardiology procedures available for use as diagnostic techniques in patients with definite or suspected cardiovascular disease. The usefulness of myocardial imaging, radionuclide angiocardiography, and other radionuclide cardiovascular imaging techniques is classified within specific disease states. The clinical utility of each technique is graded from I to IV, depending on the clinical importance of the technique (I equals most important; IV equals not indicated). A grade of V is given for methods now considered to be in their research phase. The usefulness of these methods is discussed in patients with acute ischemic heart disease, chronic ischemic heart disease, valvular heart disease, pulmonary vascular disease, and hypertensive heart disease. Selected references are provided.
To better correlate the appearance of avascular necrosis (AVN) of the femoral head on magnetic resonance (MR) images with the stage of disease, MR images of 56 proved AVN lesions were compared with staging from corresponding radiographs (n = 56), Tc-99m scans (n = 41), and grade of symptoms (n = 28). Fractures complicating AVN were seen in 28 (50%) of 56 radiographs (radiographic stages III-V). With long repetition (TR) and echo delay (TE) times, a characteristic "double line sign" consisting of high signal intensity inside a low-intensity peripheral rim was seen in 45 lesions (80%). The central region within the rim was isointense with marrow fat on both short and long TR and TE images in 20 (71%) of 28 lesions uncomplicated by fracture (stages I-II) but in only four (14%) of 28 stage III-V lesions (P less than .001). Symptoms were least severe in lesions isointense with fat and most severe in lesions with low-signal central regions at short and long TRs and TEs. The peripheral double line sign on long TR/TE images may add specificity to the diagnosis of AVN by MR imaging. A chronologic pattern of central MR signal features is presented which may allow staging of AVN by MR imaging.
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Radionuclide imaging has been helpful to oncologists in the initial evaluation and follow-up of patients with primary and metastatic disease. With the introduction of ultrasound and computed tomography, there has been some reduction in the number of radionuclide imaging procedures. These imaging modalities should be used to complement one another. With the introduction of single-photon emission computed tomography in clinical nuclear medicine, there will be a significant improvement in the sensitivity, accuracy, and quantitative ability to detect abnormal lesions. There are intensive efforts in the development of tumor imaging using new agents. Specific antibodies for surface tumor antigens can be labeled with radioisotopes and used as tools for screening primary tumors and metastatic lesions. Therefore, for the present, radionuclide imaging will continue to contribute to clinical oncology.
Presently, radionuclide imaging in hepatobiliary disease is mainly used to evaluate the functional aspect in hepatobiliary disease. For the evaluation of hepatic function, three kinds of radiopharmaceuticals are now commercially available: these are the Kupffer-cell oriented radiotracer of 99mTc-colloid, the hepatocyte oriented radiotracer of 99mTc-PMT, and the receptor-binding radiopharmaceutical of 99mTc-GSA. These radiopharmaceuticals must be properly used, according to the purposes. 99mTc-PMT can be used to determine the degree of functional disorder in acute hepatic disease and evaluate the severity of diffuse hepatic disease, whereas 99mTc-colloid can effectively evaluate the potential etiology of the disease process and its chronicity. And 99mTc-GSA may also be used to evaluate the severity of the disease. In particular, the hepatic functional reserve must be evaluated with 99mTc-GSA. The biliary patency from the intrahepatic bile canaliculi to the common bile duct can be effectively evaluated with 99mTc-PMT. The diagnosis of acute cholecystitis is most reliably made by radionuclide imaging. And radionuclide imaging is sometimes to be used for the differentiation of cholestasis. In particular, the discrimination among the disease entities of chronic intermittent intrahepatic cholestasis including primary biliary cirrhosis, primary sclerosing cholangitis and juvenile intrahepatic bile duct hypoplasia can be made. Moreover, it is also be used in evaluating constitutional hyperbilirubinemia, biliary leakage, infantile jaundice and gallbladder or syphinctor Oddi motor dysfunction.
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An operator-interactive algorithm to achieve superposition of organ images has been used with a dedicated nuclear medicine computer system. Its purpose is to achieve organ registration in 128 X 128 digitized images before a direct numerical comparison of the regional distribution of a deposited radiotracer is performed. The accuracy and reproducibility of the algorithm for myocardial images has been tested by four operators, using a set of 28 image pairs in which the relative position of the heart differed by more than 10 mm for each pair. Comparing their results with the known displacements on two occasions provided an assessment of these two important parameters. The accuracy and reproducibility for superposing myocardial images by this digital technique are found to be well within the spatial resolution (FWHM) of the imaging system of the Tl-201 tracer studied.
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