ASSESSMENT OF CEREBRAL PERFUSION IN CHRONIC TOBACCO USERS THROUGH SPECT (SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY) USING TC-99M HMPAO (METASTABLE TECHNETIUM-99 LABELLED HEXA- METHYL PROPYLENE AMINE OXIME)

Cerebral Perfusion in Chronic Tobacco Users

Abstract

Objective: To determine an association between chronic tobacco use and changes in cerebral perfusion through semi-quantitative scintigraphic assessment employing metastable Technetium-99 labelled hexa-methyl propylene amine oxime single photon emission computed tomography (Tc-99m HMPAO SPECT).
Design: Case-control study.
Place and duration of study: The study was conducted at the Department of Medical Sciences, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, from Oct 2001 to May 2002.
Patients and Methods: Regional cerebral perfusion in 48 chronic tobacco users was evaluated, utilising a normal database created by HMPAO brain scans of 20 non-tobacco users. Subjects were classified into chronic tobacco users and non-tobacco users through the use of the smoking index (SI). [Smoking Index = Number of years of tobacco use x Number of cigarettes smoked per day]. SI value of 100 was taken as the cut-off value. Regions of interest (ROIs) were declared hypoperfused or hyperperfused if their percentage perfusion values relative to the average perfusion per pixel of the whole slice under evaluation did not fall within + 2 standard deviation (SD) of the mean regional perfusion in the corresponding ROI, in the normal control group.
Result: Chronic tobacco users showed 164 hypoperfused ROIs (6.57%) and 138 hyperperfused ROIs (5.53%) out of 2496 ROIs assessed, whereas the normal controls showed only 15 hypoperfused (1.44%) and 27 hyperperfused (2.60%) ROIs out of 1040 ROIs assessed (P < 0.001).
Conclusion: Cerebral perfusion in chronic tobacco users was found to be significantly decreased compared to the non-tobacco users.