[Application of 99mTc-DTPA in evaluation of blood-brain barrier permeability in patients receiving whole brain irradiation].
OBJECTIVE
To study the pattern of blood-brain barrier (BBB) permeability changes during whole brain radiotherapy (WBRT) for metastatic brain tumor.


METHODS
Twenty patients with metastatic brain tumors receiving WBRT by 6 MV X-ray underwent (99)mTc-DTPA brain SPECT before and during WBRT (20, 40 Gy) and at 2 weeks after the end of irradiation. A frame of transverse (99)mTc-DTPA brain SPECT image that best displayed the brain metastasis was chosen, and the regions of interest (ROI) were defined in the tumor foci (T), the contralateral normal brain tissue (N) and the background outside the soft tissues around the cranium (B). The radioactive counts of every ROI were measured and the ratios of the total counts (T/B and N/B) before and during WBRT (20 Gy, 40 Gy) and at 2 weeks after the irradiation were calculated.


RESULTS
The average T/B and N/B in the 20 patients with 30 brain metastases was 142.2-/+51.1 and 82.6-/+42.3 before WBRT, 260.3-/+121.5 and 150.7-/+72.5 during 20 Gy WBRT, 251.6-/+118.3 and 161.8-/+68.4 during 40 Gy WBRT, and 250.3-/+117.2 and 158.6-/+73.5 at 2 weeks after the irradiation, respectively. The measurements during WBRT (20 and 40 Gy) and at 2 weeks after the irradiation group underwent no significant variations (P>0.05), but showed significant differences from those before WBRT (P<0.05).


CONCLUSIONS
Irradiation causes direct damage of the BBB function, and the permeability of the BBB increases significantly during and within 2 weeks following 20 and 40 Gy WBRT, which provides the optimal time window for interventions with chemotherapy.
Department of Radiotherapy, Foshan First People's Hospital, Foshan 528000, China. jjun@fsyyy.com
Jun
J
Jiang
Wei-hong
WH
Wei
Yan-lin
YL
Feng
Yu-chao
YC
Zhou
Wei-jun
WJ
Luo
Jian-wei
JW
Yuan
Guo-yi
GY
Zhang
Zhi-Qian
ZQ
Lü
D000328:Adult; D000368:Aged; D001812:Blood-Brain Barrier / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary*; D002199:Capillary Permeability / Q000502:physiology*; D016371:Cranial Irradiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013670:Sodium Pertechnetate Tc 99m; D015899:Tomography, Emission-Computed, Single-Photon
D013670:Sodium Pertechnetate Tc 99m