PURPOSE: To give a help in the interpretation of cardiac cine-MR examination, the extent, shape, and timing of appearance of signal void regions near atrioventricular(A-V) valve prospectively evaluated in the healthy population. MATERIALS AND METHODS: Using an axial gradient-echo technique with small flip angle, repetition time(TR) of 36 msec and echo time(TE) of 22 msec, 20 volunteers without known valvular abnormalities undertook cardiac cine-MR imaging including atrioventricualr valve areas. RESULTS: Transient signal void was observed within the atrium near the tricuspid(13/20 = 65%) and mitral valves(9/20 = 45%), respectively, which is so called "physiologic atrioventricular valvular insufficiency". Eight subjects revealed the signal void areas near both tricuspid and mitral valves but, 5 subjects didnot show any evidences of physiologic insufficiency. This physiologic condition does not extend more than lcm proximal to A-V valve plane and is generally observed only during early systole. Its morphology is semilunar or triangular configuration with the base to the valve plane in most cases of normal tricuspid insufficiency and small globular appearance in most cases of normal mitral insufficiency. CONCLUSION: Awareness of normal signal void areas near the A-V valve and their characteristics is critical in the interpretation of cardiac cine MR examinations and maybe helpfal in the study of the normal cardiac physiology.
Magnetic Resonance Imaging* ; Mitral Valve ; Mitral Valve Insufficiency ; Physiology ; Prospective Studies ; Systole ; Volunteers

PURPOSE: Bilateral high signal intensity in basal ganglia on Tl-weighted images is unusual. the purpose of this study is to describe the pattern of high signal intensity and underlying disease. METHODS AND MATERIALS: During the last three years, 8 patients showed bilateral high signal intensity in basal ganglia on Tl-weighted image, as compared with cerebral white matter. Authors analized the images and underlying causes retrospectively. Of 8 patients, 5 were male and 3 were female. The age ranged from 15 days to 79 years. All patient were examined by a 0.5T superconductive MRI. Images were obtained by spin echo multislice technique. RESULTS: Underlying causes were 4 cases of hepatopathy, 2 cases of calcium metabolism disorder, and one case each of neurofibromatosis and hypoxic brain injury. These process were bilateral in all cases and usually symmetric. In all cases the hyperintense areas were generally homogenous without mass effect or edema, although somewhat nodular appearence was seen in neurofibromatosis. Lesions were located in the globus pallidus and internal capsule in hepatopathy and neurofibromatosis, head of the caudate nucleus in disorder of calcum metabolism, and the globus pallidus in hypoxic brain injury. CONCLUSION: Although this study is limited by its patient population, bilateral hyperintense basal ganglia is associated with various disease entities. On analysis of hyperintense basal ganglia lesion, the knowledge of clinical information improved diagnostic accuracy.
Basal Ganglia* ; Brain ; Brain Injuries ; Calcium Metabolism Disorders ; Caudate Nucleus ; Edema ; Female ; Ganglia ; Globus Pallidus ; Head ; Humans ; Internal Capsule ; Magnetic Resonance Imaging ; Male ; Metabolism ; Neurofibromatoses ; Retrospective Studies

PURPOSE: Retrospective studies were carried out to evaluate the usufulness of CT in differentiating benign or malignant intrahepatic duct(IHD) dilatation due to extrahepatic duct(EHD) obstruction. MATERIALS AND METHODS: Among 75 cases of IHD dilatation, 35 cases(47%) which did not show causative lesion on CT were classified into central or peripheral type according to the extent of the dilatation and into pruned or beaded form according to its pattern. We considered central type or pruned form as a benign feature while peripheral type or beaded from as a malignant feature. Predictions of benignancy or malignancy were made according to the pattern and the extent of IHD dilatation. In all 75 cases, maximum caliber of IHD at portal vein bifurcation were examined. RESULTS: In regard to the classification of the extent, 80% (28 out of the 35 cases:11 of 15 cases of benignancy and 17 of 20 cases of malignancy) of our prediction was correct. As to the classification of the pattern, similar results(82% correct prediction) were obtained(14 out of 17 cases):ln 15 cases of benignancy, we observed six cases of pruning and 1 case of beading. Among the 20 cases of malignancy, two cases of pruning and eight cases of beading of IHD dilatation were observed. Mean diameters of IHD at portal vein bifurcation were 10.1ram in benignancy and 15.1mm in malignancy.(Diameters less than 11mm was suggestive of benignancy(alpha =0.05). CONCLUSION: Evaluation of the extent, the pattern, and the degree of IHD dilatation is necessary in differential diagnosis of benignancy and malignancy of EHD obstruction. We conclude that CT is a useful tool for this purpose of differential diagnosis of the benignancy and the malignancy of extrahepatic biliary obstruction.
Classification ; Diagnosis, Differential ; Dilatation* ; Portal Vein ; Retrospective Studies ; Tomography, X-Ray Computed*