Clinical Monitoring of Early Pathophysiologic Events

Feature-based, automated segmentation of cerebral infarct patterns using T2- and diffusion-weighted imaging

Diffusion-weighted imaging enables the diagnosis of cerebral ischemias very early, thus supporting therapies such as thrombolysis. However, morphology and tissue-characterizing parameters (e.g. relaxation times or water diffusion) may vary strongly in ischemic regions, indicating different underlying pathologic processes. As the determination of the parameters by a supervised segmentation is very time consuming, we evaluated whether different infarct patterns may be segmented by an automated, multidimensional feature-based method using a unified segmentation procedure. Ischemias were classified into 5 characteristic patterns. For each class, a 3D histogram based on T(2)- and diffusion-weighted images as well as calculated apparent diffusion coefficients (ADC) was generated from a representative data set. Healthy and pathologic tissue classes were segmented in the histogram as separate, local density maxima with freely shaped borders. Segmentation control parameters were optimized in a 3-step procedure. The method was evaluated using synthetic images as well as results of a supervised segmentation. For the analysis of cerebral ischemias, the optimal control parameter set led to sensitivities and specificities between 1.0 and 0.9.

Brain MRI in peripartum seizures: usefulness of combined T2 and diffusion weighted MR imaging

Peripartum seizure is a serious disease with significant morbidity and mortality for women and their unborn children. The underlying etiologies are varied, with eclampsia and venous stroke being the most common causes. T2 weighted MR images of the brain show hyperintense lesions in either condition. Diffusion weighted MR images (DWI) of the brain is abnormal in strokes. We report three cases of eclampsia with abnormal T2 weighted images, but normal DWI. Diffusion weighted MR images in association with T2 weighted MR images can be extremely helpful in evaluation of women with new onset peripartum seizures.