A hybrid display system for computer processed scintigrams.
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Brain↗
Biomedical subjects
S Pizer
Publications and source records attributed to S Pizer.
Quantitative digital fluorography. Computer vs. human estimation of vascular stenoses.
Digital subtracted images of iodinated rods, incorporating accurately measured areas of eccentric stenosis were obtained. The average subjective estimations of fractional area reduction (211 readings each) by three experienced angiographers were compared with values obtained using an interactive computer algorithm using the densitometric data. Results were analyzed to identify major influences on accuracy, including iodine concentration, vessel width, absolute severity of the stenosis, and vessel orientation. While no single factor appeared to seriously affect human accuracy, computer readings were significantly influenced by the tilt of the vessel in relation to the x-ray beam. Various potential sources of error including beam hardening, stenosis geometry, and scattering are discussed and appropriate algorithm corrections suggested. The importance of the availability of a reliable and accurate method to quantify vascular stenosis and volume of stenotic material is stressed.
Absorptiometry, Photon↗
Examination of the extracranial carotid bifurcation by thin-section dynamic CT: direct visualization of intimal atheroma in man (Part 2).
Examination of the extracranial carotid bifurcation by thin-section computed tomographic (CT) scans after bolus, high-volume contrast enhancement allowed detection of more disease than did arteriograms in six of eight consecutive patients with transient ischemic attacks. In four patients this was on the clinical side of the lesion; in two the disease was in the asymptomatic carotid artery. One patient appeared to show a carotid ulcer; the ulcer was detected on CT. However, at surgery and subsequent histology, the surface of the lesion was endothelialized. The carotid CT examination is performed in the scanner "dead time" between unenhanced and enhanced head CT scans using the same contrast material for both studies. The examinations covers 3-3.6 cm of the carotid bifurcation region. Thin-section CT of the extracranial carotid arteries is a noninvasive examination that on preliminary evaluations appears to have sensitivity at least equal to that of carotid angiography in the detection of intimal disease.
Adult↗