Quantitative T1rho magnetic resonance imaging of RIF-1 tumors in vivo: detection of early response to cyclophosphamide therapy.
This study compares two potential magnetic resonance imaging (MRI) indices for noninvasive early detection of tumor response to chemotherapy: the spin-lattice relaxation in the rotating frame (T1rho) and the transverse relaxation time (T2). Measurements of these relaxation parameters were performed on a s.c. murine radiation-induced fibrosarcoma (RIF-1) model before and after cyclophosphamide treatment. The number of pixels exhibiting T1rho values longer than controls in viable regions of the tumor increased significantly as early as 18 h after drug administration and remained elevated up to 36 h after treatment (P < 0.005). Although a trend of increasing T2s relative to controls was noted in viable regions of the tumor 36 h after treatment, the changes were not statistically significant. Histological examination indicated a decrease in mitotic index that paralleled the changes in T1rho. We conclude that T1rho measurements may be useful for noninvasive monitoring of early response of tumors to chemotherapy.
Duvvuri
U
U
Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA.
Poptani
H
H
Feldman
M
M
Nadal-Desbarats
L
L
Gee
M S
MS
Lee
W M
WM
Reddy
R
R
Leigh
J S
JS
Glickson
J D
JD
D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003520:Cyclophosphamide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005354:Fibrosarcoma / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008809:Mice, Inbred C3H; D009381:Neoplasms, Radiation-Induced / Q000188:drug therapy* / Q000473:pathology*
D018906:Antineoplastic Agents, Alkylating; D003520:Cyclophosphamide