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Biomedical subjects

R Biscay Lirio

Publications and source records attributed to R Biscay Lirio.

2 recordsLinked to original sources

Localization error in biomedical imaging.

Measures of false positive (FP) and false negative (FN) localization error are defined to assess the accuracy of diagnostic imaging procedures. These measures involve the weighting of FP and FN pixels in accordance to their distances from the true localization of the lesion and the region detected as abnormal by the classifier. The distance-based localization receiver operating characteristic (DL-ROC) curve is defined to describe the dependence of the FP and FN localization measures on the classifier's decision threshold. A computer system is presented for the analysis of localization experiments according to these concepts. As an illustration, the accuracy of two types of brain electric topographic montage is studied in the localization of brain tumors and sites of stroke.

Brain Ischemia

Brain electrical field measurements unaffected by linked earlobes reference.

Recent theoretical analysis supports the possibility that using a linked earlobe reference in EEG studies might appreciatively distort the measured electrical field due to current flow over a low resistance path across the wire joining both ears. Such an effect would invalidate published quantitative EEG norms. Evidence for the balancing effect of this distortion was sought for in the EEG of 4 patients with well localized unilateral lesions, a situation in which this distortion would be most apparent. Statistical tests failed to reveal significant differences between EEGs recorded when ears were linked or unlinked. An analysis of the equivalent circuit reveals that a high skin/electrode impedance effectively makes the linked ear reference behave as an ordinary reference.

Brain