Use of 123I-IMP brain SPET to predict outcome following STA-MCA bypass surgery: cerebral blood flow but not vasoreactivity is a predictive parameter.
Superficial temporal artery - middle cerebral artery (STA-MCA) bypass surgery might improve the cerebral blood flow (CBF) but fail to reduce the risk of post-surgical events such as ischaemic stroke. In this study, we studied retrospectively whether the risk of post-surgical events corresponded to the change in resting CBF and/or the change in vasoreactivity observed before and after STA-MCA surgery using N-isopropyl-I-123-p-iodoamphetamine (123I-IMP) brain single-photon emission tomography (SPET). 123I-IMP brain SPET images obtained at rest and following acetazolamide challenge both before and after STA-MCA surgery were studied in 30 patients. Resting CBF was estimated semiquantitatively using the resting count ratios of the middle cerebral artery (MCA) area to the cerebellum. Acetazolamide c hallenge was assumed to result in an average increase in flow of 40% in the cerebellum. The vasoreactive response was then estimated as the ratio of the change in counts (acetazolamide - rest) to the resting cerebellar counts multiplied by 1.4. We classified 14 patients (50.5 +/- 19.3 years) into group I, who h a change in their resting CBF from before to after surgery of >10%, and 16 patients (54.0 +/- 18.8 years) into group II, who had a change in their resting CBF from before to after surgery of ¿leq10%. Oxygen-15 positron emission tomography (PET) studies were performed in five patients from group I and five patients from group II. One post-surgical event occurred in group I while there were eight post-surgical events in group II (P<0.05). Resting CBF improved by 20.4% +/- 7.5% in group I and by 0.9% +/- 6.9% in group II patients after surgery (P<0.001). No significant difference in the improvement in vasoreactivity was observed between group I patients (32.6% +/- 17.7%) and group II patients (24.6% +/- 15.6%) following surgery. Patients in the group I PET subset showed normalization of oxygen extraction fraction (OEF) from 0.59 +/- 0.09 before surgery to 0.46 +/- 0.06 after surgery (P<0.05), while patients in the group II PET subset showed no statistical difference in OEF before surgery (0.58 +/- 0.14) and after surgery (0.54 +/- 0.05). We conclude that the outcome of STA-MCA bypass surgery can be predicted by the improvement in resting CBF but not by the improvement in vasoreactivity.
Kume
N
N
Department of Radiology, National Cardiovascular Center, Osaka, Japan.
Hayashida
K
K
Iwama
T
T
Cho
I
I
Matsunaga
N
N
D000086:Acetazolamide / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000662:Amphetamines; D001921:Brain / Q000000981:diagnostic imaging*; D002548:Cerebral Revascularization / Q000009:adverse effects; D002560:Cerebrovascular Circulation / Q000187:drug effects; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012307:Risk Factors; D014055:Tomography, Emission-Computed; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D000662:Amphetamines; D007457:Iodine Radioisotopes; D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014665:Vasodilator Agents; C041336:4-iodoamphetamine; D000086:Acetazolamide