Measurement of tumor vascular damage in mice with 99mTc-MIBI following photodynamic therapy.
The clinical perfusion agent 99mTc-MIBI was used to monitor changes in tumor vascular perfusion (TVP) induced by Photofrin (PII)-mediated photodynamic therapy (PDT). BALB/c mice bearing an EMT-6 tumor on each hind thigh were given an intravenous injection of 1, 2 or 5 mg kg-1 PII. Twenty-four hours later, one tumor was illuminated (600-650 nm, 200 mW cm-2, 400 J cm-2) while the other served as a control. At various time intervals after PDT (0, 2 and 24 h) mice received an intravenous injection of 99mTc-hexakismethoxyisobutylisonitrile (MIBI) (0.18 MBq g-1) and were sacrificed 2 min later. The light-treated and the untreated tumors were then dissected, the radioactivity was counted and the percentage of the injected dose per gram of tumor (%ID g-1) was calculated as a measure of TVP. We observed that TVP is drug dose dependent, develops progressively with time post-PDT and is inversely related to PDT efficacy. Our data show that early tumor retention of 99mTc-MIBI is a simple method to assess TVP and vascular damage induced by PDT.
Brasseur
N
N
MRC Group in the Radiation Sciences, University of Sherbrooke, Québec, Canada.
Lewis
K
K
Rousseau
J
J
van Lier
J E
JE
D000818:Animals; D003287:Contrast Media; D008325:Mammary Neoplasms, Experimental / Q000098:blood supply* / Q000188:drug therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D010477:Perfusion; D010778:Photochemotherapy; D017256:Technetium Tc 99m Sestamibi / Q000494:pharmacology*
D003287:Contrast Media; D017256:Technetium Tc 99m Sestamibi