Carbon dioxide reactivity by consecutive technetium-99m-HMPAO SPECT in patients with a chronically obstructed major cerebral artery.
In the management of major cerebral artery obstruction, cerebral perfusion reserve is key to introducing cerebral revascularization surgery. The purpose of this study was to evaluate the feasibility of assessing cerebral perfusion reserve by consecutive 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) SPECT with 5% carbon dioxide (CO2) inhalation.


METHODS
The CO2 inhalation and consecutive 99mTc-HMPAO SPECT study was performed on 30 chronic ischemic cerebrovascular disease patients with unilateral major cerebral artery obstruction and on 27 patients without. CO2 reactivity was expressed as the percent increase of 99mTc-HMPAO accumulation from the baseline (%Change) and as a constant k' that was the ratio of 99mTc-HMPAO accumulation per 1 mmHg change of end-tidal CO2 tension by exponential curve fitting.


RESULTS
The mean %Change and k' in the middle cerebral artery (MCA) territory on the side without an obstructive lesion or in the cerebellum ranged from 10.0% to 11.1% and from 0.98% to 1.13% per mmHg, respectively. In the MCA territory, an obstructive lesion was noted in 5.9% versus 0.54% per mmHg in the contralateral MCA territory (p < 0.01). Eleven of 30 patients with major cerebral artery obstruction revealed significant asymmetry in the k' value between bilateral MCA territories.


CONCLUSIONS
The results showed compromised cerebral perfusion reserve in the obstructed major cerebral artery territory. The present method was proven clinically useful for evaluating cerebral perfusion reserve in patients with unilateral major cerebral artery obstruction.
Oku
N
N
First Department of Internal Medicine, Osaka University Medical School, Japan.
Matsumoto
M
M
Hashikawa
K
K
Moriwaki
H
H
Okazaki
Y
Y
Seike
Y
Y
Handa
N
N
Uehara
T
T
Kamada
T
T
Nishimura
T
T
D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000502:physiology; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002908:Chronic Disease; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
D015609:Organotechnetium Compounds; D010091:Oximes; D002245:Carbon Dioxide; D019690:Technetium Tc 99m Exametazime