Contrast-enhanced magnetic resonance imaging estimation of altered capillary permeability in experimental mammary carcinomas after X-irradiation.
OBJECTIVE
Dynamic magnetic resonance imaging (MRI) enhanced with a macromolecular contrast medium, albumin-(Gd-DTPA)35, was used to detect changes in microvascular characteristics in R3230 mammary adenocarcinomas induced by x-irradiation.


METHODS
Tumors were implanted in either flank in nine rats. One of the tumors was exposed to single-dose x-irradiation (30 Gy) 3 days before MRI. The contralateral control tumor was shielded from irradiation.


RESULTS
Capillary permeability to macromolecular contrast medium in irradiated tumors was elevated significantly (P < .05) compared to the control nonirradiated tumors. The mean estimated permeability surface area product for the irradiated tumors increased more than three-fold; 0.511 +/- .046 mL hr-1 cm-3 compared with 0.121 +/- .011 mL hr-1 cm-3 for the nonirradiated tumors. This radiation-induced increase in permeability was corroborated using a macromolecular Evans blue-protein complex measured in the same tumors using an invasive spectrophotometric technique.


CONCLUSIONS
Dynamic MRI-enhanced with macromolecular contrast medium permits noninvasive quantitative estimates of capillary permeability in tumors, with and without x-irradiation. Because the transendothelial permeability for macromolecular solutes likely influences tumoral accumulation of macromolecular chemotherapeutic agents, this noninvasive technique may prove to be clinically useful in tailoring tumor treatment programs which combine radiation and chemotherapy.
Cohen
F M
FM
Department of Radiology, University of California, San Francisco 94143-0628.
Kuwatsuru
R
R
Shames
D M
DM
Neuder
M
M
Mann
J S
JS
Vexler
V
V
Rosenau
W
W
Brasch
R C
RC
D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy; D000418:Albumins; D000818:Animals; D002196:Capillaries / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D002199:Capillary Permeability / Q000528:radiation effects*; D003287:Contrast Media; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D005070:Evans Blue; D005682:Gadolinium; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging / Q000379:methods; D008325:Mammary Neoplasms, Experimental / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy; D009368:Neoplasm Transplantation; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011859:Radiography; D051381:Rats; D011916:Rats, Inbred F344; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy; D013053:Spectrophotometry
D000418:Albumins; D003287:Contrast Media; D009942:Organometallic Compounds; C058946:albumin-(gadolinium-DTPA); D005070:Evans Blue; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA