High-b-value diffusion-weighted MR imaging for pretreatment prediction and early monitoring of tumor response to therapy in mice.
OBJECTIVE
To evaluate the use of diffusion-weighted magnetic resonance (MR) imaging with standard and high b values for pretreatment prediction and early detection of tumor response to various antineoplastic therapies in an animal model.


METHODS
Mice bearing C26 colon carcinoma tumors were treated with doxorubicin (n = 25) and with aminolevulinic acid-based photodynamic therapy (n = 23). Fourteen mice served as controls. Conventional T2-weighted fast spin-echo and diffusion-weighted MR images were acquired once before therapy and at 6, 24, and 48 hours after treatment. Pretreatment and early (1-2 days) posttreatment water diffusion parameters were calculated and compared with later changes in tumor volumes measured on conventional MR images by using the Pearson correlation test.


RESULTS
In chemotherapy-treated tumors, a significant correlation (P <.002, r = 0.6) was observed between diffusion parameters that reflected tumor viability, measured prior to treatment, and changes in tumor volumes after therapy. This correlation implies that tumors with high pretreatment viability will respond better to chemotherapy than more necrotic tumors. In tumors treated with photodynamic therapy, no such correlation was found. Changes observed in water diffusion 1-2 days after treatment significantly correlated with later tumor growth rate for both therapies (P <.002, r = 0.54 for photodynamic therapy; P <.0003, r = 0.61 for chemotherapy).


CONCLUSIONS
High-b-value diffusion-weighted MR imaging has potential use for the early detection of response to therapy and for predicting treatment outcome prior to initiation of chemotherapy.
Roth
Yiftach
Y
Advanced Technology Ctr and Oncology Inst, Chaim Sheba Medical Ctr, Tel-Hashomer 52621, Israel.
Tichler
Thomas
T
Kostenich
Genady
G
Ruiz-Cabello
Jesus
J
Maier
Stephan E
SE
Cohen
Jack S
JS
Orenstein
Arie
A
Mardor
Yael
Y
D000818:Animals; D003110:Colonic Neoplasms / Q000175:diagnosis* / Q000188:drug therapy*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011237:Predictive Value of Tests; D011300:Preoperative Care