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Biomedical subjects

N M Alpert

Publications and source records attributed to N M Alpert.

131 records · Page 8Linked to original sources
PubMedDate not supplied

Performance evaluation of an automated system for registration and postprocessing of CT scans.

A prototype system optimized for automatic registration of CT scans and applications such as subtraction enhancement and CT angiography was evaluated. Co-registration was performed on 50 studies of various types, including CT angiograms. Mean registration speed was 109 s; accuracy was 2.0 mm. Examples of subtraction enhancement and automatic extraction of the vascular tree are provided. Unattended registration was demonstrated in routine application. Subtraction-enhanced images and extraction of the vascular tree may be useful in clinical practice.

Electronic Data Processing↗
PubMedDate not supplied

Quantitative PET measurements of regional myocardial blood flow: observations in humans with ischemic heart disease.

This review focuses on several related issues concerning positron emission tomography measurements of regional myocardial blood flow using 13-N-ammonia in humans. The effect of partial volume correction on estimates of K1, the model parameter describing myocardial blood flow, is considered. In addition a new method for computing K1 images of myocardial flow distribution is briefly described and compared to a standard method. Potential differences between K1 and equilibrium levels of 13-N-ammonia in the myocardium for estimation of myocardial blood flow are discussed also. The issue of heterogeneity of myocardial blood flow and flow reserve in normal volunteers is considered from the clinical point of view in terms of evaluation of patients with ischemic heart disease. Finally, the use of absolute measurement of adenosine-stimulated myocardial blood flow to assess physiological significance of coronary artery stenoses is addressed.

Adenosine↗
PubMedDate not supplied

Positron imaging of cerebral blood flow during continuous inhalation of C15O2.

This investigation tests the hypothesis that the normal cerebral image obtained non-invasively during continuous inhalation of C15O2 is related to cerebral blood flow. Trace amounts of CO2 labeled with the positron-emitting radionuclide 15O were administered to 4 normal subjects at normo- and hypocapnia and to 2 of these subjects at hypercapnia. Hypocapnia typically caused a marked decrease in cerebral 15O activity, and hypercapnia a small increase in activity. The relative difference in the change in count rate in response to hypo- and hypercapnia is what one would expect if the activity represented bloow flow, according to a mathematical model which assumes the 15O label enters the brain as water of perfusion. The findings in this study suggest that the normal cerebral image obtained during continuous inhalation of C15O2 is related to cerebral blood flow, but in a non-linear fashion, and that the technique would be more sensitive to ischemic events than to hyperemic phenomena.

Adult↗
PubMedDate not supplied

Digital computers in nuclear medicine. An overview.

Just a few years ago the role of digital processing and display in nuclear medicine was in question. With the emergence of applications that make the value of digital processing more evident plus the favorable trends in digital equipment price and performance, the controversy has died away. The use of computers to acquire, process, and display radionuclide measurements is now routine in many hospitals and research laboratories.

Computers↗