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]

ABSTRACT

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. 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]. Cerebral perfusion in chronic tobacco users was found to be significantly decreased compared to the non-tobacco users