Positron emission tomography INDEX

Neuroimaging techniques assessing cerebral blood flow (CBF] and cerebral metabolic rate provide powerful windows onto the effects of ECT. Nobler et al. [1994] assessed cortical CBE using the planar xenon-133 inhalation technique in 54 patients. The patients were studied just before and 50 minutes after the sixth ECT treatment. At this acute time point, unilateral ECT led to postictal reductions of CBF in the stimulated hemisphere, whereas bilateral ECT led to symmetric anterior frontal CBE reductions. Regardless of electrode placement and stimulus intensity, patients who went on to respond to a course of ECT manifested anterior frontal CBE reductions in this acute postictal period, whereas nonresponders failed to show CBF reductions. Such frontal CBF reductions may reflect functional neural inhibition and may index anticonvulsant properties of ECT. A predictive discriminant function analysis revealed that the CBF changes were sufficiently robust to correctly classify both responders (68% accuracy] and nonresponders (85% accuracy]. More powerful measures of CBF and/or cerebral metabolic rate, as can be obtained with positron-emission tomography, may provide even more sensitive markers of optimal ECT administration. 

Figure 9 Effect of cyclosporin A on the brain (A) and plasma (B) concentration of nC verapamil in healthy volunteers. (A) 1 -Verapamil ( 0.2 mCi/kg) was administered to healthy volunteers intravenously, approximately one minute before and after one-hour infusion of cyclosporin A (2.5 mg/kg/h). (B) PET images of a normal human brain after nC-verapamil administration in the absence or presence of cyclosporin A. Images shown are in SUV summed over a period of 5 to 25 minutes, which is an index of regional radioactivity uptake normalized to the administered dose and weight of the subject. Abbreviations PET, positron emission tomography SUV, standardized uptake value. Source From Ref. 218.

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