One-day protocol for cerebral perfusion reserve with acetazolamide.

UNLABELLED

A one-day protocol with a double injection of 99mTc-ECD was introduced for the assessment of cerebral perfusion reserve with acetazolamide (ACZ). The purpose of this study was to investigate the feasibility and effectiveness of this protocol.

METHODS

Thirty subjects were given double injections of 99mTc-ECD (first dose 370 MBq; second dose 740 MBq) for consecutive brain perfusion studies. Serial dynamic SPECT scans (1 min x 50 frames) were performed with the first set of SPECT data obtained by totaling the data for the frames taken between 5 and 20 min, and the second by subtracting the decay and dose-corrected initial SPECT data from the sum of the data obtained between 35 and 50 min. To evaluate the feasibility and effectiveness of the procedure, 23 of the 30 subjects were injected with ACZ 14 min after the first dose. To evaluate the reproducibility, seven subjects were not given the ACZ. The washout rate (WR) was calculated for three stages (WR1 = from 6 to 14 min, WR2 = from 20 to 28 min, and WR3 = from 36 to 44 min). Regional count increase (percent increase) and the percent count difference between normal and affected side (percent difference) were also calculated.

RESULTS

Values for WR1, WR2 and WR3 did not show significant differences among the stages (WR1 = -1.43% +/- 6.09%, WR2 = -0.65% +/- 6.57%, and WR3 = -1.60% +/- 4.28%; F-value = 0.33, p-value = 0.72). Reproducibility was excellent (second SPECT = 0.964 x first SPECT; r = 0.997). Mean count increase after ACZ was 21.7%. In patients with unilateral cerebrovascular disease, the percent increase after ACZ loading was significantly greater on the normal side (26.6% +/- 13.0%) than on the affected side (19.3% +/- 13.2%) (p < 0.01), resulting in a significant increase in percent difference (control: 14.3% +/- 10.7%, ACZ: 19.2% +/- 11.5%; p < 0.01).

CONCLUSION

ECD washout was minimal during the first 50 min after injection and was not affected by ACZ, which supports the feasibility of this protocol. The simple procedure and short acquisition time of this method renders it clinically useful for measuring cerebral perfusion reserve.