To evaluate the heart cycle-dependent signal intensity changes in the cardiac chambers, the aorta, and the pulmonary artery, five healthy volunteers were studied with gradient-echo magnetic resonance cine loops at different heart rates. Quantitative evaluation of signal intensity on each side of the cardiac valves showed that there were changes in signal intensity due to section-entry and spin-phase phenomena but none due to the increase in heart rate. The authors conclude that there is no heart rate-dependent signal loss in healthy persons that simulates valvular dysfunction, thus suggesting that signal intensity change can be used as an indicator for this disease, independent of heart rate.

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Semiautomated ROI analysis in dynamic MR studies. Part II: Application to renal function examination.

Fast MR techniques and the application of water-soluble contrast agents allow the simultaneous examination of renal morphology and the functional aspects of glomerular filtration using bolus injections of Gd-DTPA. Spatial resolution is sufficient to resolve individual renal pyramids, but the quantitative examination of regions of interest (ROIs) is severely impeded by organ movements due to variations of the end-inspiratory position. A new image-processing scheme has been used and tested in 23 normal volunteers and patients. This scheme replaces a tedious frame-by-frame ROI analysis by positional correction of renal regions of all frames of the sequence such that the definition of the regions has to be performed only once. The signal intensities (SIs) of the local regions in each frame are used to compute statistics and to generate curves representing local temporal SI changes due to contrast agent excretion. The success rate of the procedure depends largely on the image quality and on the adherence to a proved acquisition protocol. The present article shows that the combination of MR and robust and reliable image-processing methods can be important for the highly automated analysis of a large number of images acquired as dynamic studies.

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The contribution of computerized axial tomography to the diagnosis of cerebellar and pontine hematomas.

Case histories are reported of seven patients in whom the diagnosis of cerebellar (four) or pontine hemorrhage (three) was made by computerized axial tomography (CT). In all of the patients except two the diagnosis, established on the basis of a space-occupying high absorption lesion, was proved by either operation or autopical for an intracerebral hematoma, i.e., the high absorption zone was transformed into an area of reduced density. It is concluded that CT is a highly reliable method for the diagnosis and location of posterior fossa hematomas. A CT syndrome, observed in four of the seven cases, is described consisting of a hydrocephalus with the tips of the posterior horns being filled with blood. This seems to be specific for a posterior fossa hematoma having penetrated into the fourth ventricle.

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[Research on the "benign form" of multiple sclerosis].

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