A model of the dual effect of gadopentetate dimeglumine on dynamic brain MR images

An optimized dynamic gradient echo sequence with two echoes is used to obtain data that can be analyzed with indicator dilution theory as well as with pharmacokinetic theory. Taking advantage of the simultaneity of T*(2) and T-1 information, both theories can be employed and merged to interpret consistently the observed effects of the redistribution of a contrast agent (gadopentetate dimeglumine) into the tissue from first pass onward. The regional cerebral blood volume (rCBV) and the exchange rate of the contrast agent between the vascular and the interstitial space through the blood-brain barrier are analyzed for each pixel in a two-step algorithm. Two values for rCBV are obtained with different weighting for the microvascular fraction of the blood volume. Because the analysis, called PELEAKAN, is capable of separating effects related to perfusion (through intravascular blood volume) and to leakage in places where the blood-brain barrier is damaged, it is an appropriate tool for evaluating these parameters in brain tumors, and we show clinical examples of this analysis in brain tumor patients. (C) 1999 Wiley-Liss, Inc

Evolution de la voute cranienne et du parenchyme cerebral avec l'age : etude preliminaire en IRM

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Correlation between cranial vault size and brain size over time: preliminary MRI evaluation

articleOBJECTIVES: To correlate changes of cranial vault measurements of an adult population during the aging process with brain size using the maximum width of the third ventricle in the axial AC-PC plane. MATERIALS AND METHODS: Prospective study of 126 adult subjects (range: 20 to 80 years) with normal brain MRI and without history of neuropsychiatric disorder. MEASUREMENTS INCLUDED: Cranial vault (Maximum length: Glabella-Opisthocranion, Maximum width: euryon-euryon, and maximum height: Basion-Vertex) measurements and maximum width of the third ventricle in the A C-PC plane. RESULTS: Vault measurements (length, width, high) were similar for every age group, irrespective of gender. The variability of cranial vault measurements between individuals was low (<1 cm). Cranial vault measurements were larger for men, but this was not significant when adjusted for body height Comparatively, a gradual widening of the third ventricle, with an exponential behavior, was observed with advancing age. CONCLUSION: Our results indicate that cranial vault measurements are stable over time (between 20-80 years) comparatively to brain atrophy with advancing age. The low variability of cranial vault measurements and their stability over time should be taken into account during segmentation and normalization of brain parenchymal structures