Changes in regional cerebral blood flow in irradiated regions and normal brain after stereotactic radiosurgery.
OBJECTIVE
To elucidate the radiation effect on the normal brain after stereotactic radiosurgery (SRS), we evaluated the change in regional cerebral blood flow (CBF) in targeted and extra-targeted areas according to the radiation dose given.


METHODS
Thirteen patients who underwent SRS for brain tumors or arteriovenous malformations were included in this study. Maximum radiation doses to the lesion ranged from 24 to 37 Gy. Mean and regional CBF were measured by 99mTc-HMPAO scintigraphy with graphic analysis, performed at before, 2 weeks and 3 months (5 patients) after SRS. Under the co-registration with the CT with superimposed isodose distribution, ROIs were set on target (37-20 Gy), peri-target (20-5 Gy) and out-of-field (5-2 Gy and less than 2 Gy) areas on the quantitative SPECT images.


RESULTS
Significant reductions in mean CBF (by 7%) and regional CBF in the peri-target areas (by 5-7%) and out-of-field areas (by 6-22%) were recognized at 2 weeks and 3 months after SRS. Regional CBF in the target and peri-target areas did not significantly change, presumably because there was little or no normal tissue in these areas.


CONCLUSIONS
These results suggest that subclinical regional CBF reduction occurs after SRS in the normal brain in out-of-field of radiation.
Department of Radiology, Kanazawa Medical University, Uchinada, Kahoku, Japan. staki@kanazawa-med.ac.jp
Suzuka
S
Taki
Kotaro
K
Higashi
Manabu
M
Oguchi
Hiroyasu
H
Tamamura
Shiro
S
Tsuji
Kiyotaka
K
Ohta
Hisao
H
Tonami
Itaru
I
Yamamoto
Kazuya
K
Okamoto
Hideaki
H
Iizuka
D000328:Adult; D000368:Aged; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000528:radiation effects*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D002560:Cerebrovascular Circulation / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D016634:Radiosurgery / Q000009:adverse effects*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime