A study shows that daily qualitative imaging with intravoxel incoherent motion (IVIM) MRI can feasibly monitor treatment response to prostate cancer. The findings appeared in Frontiers in Oncology.
This study comprised of 43 patients who were all treated with 20 fractions of 3 Gy on a 1.5 T MR-linac. The researchers obtained IVIM measurements on each treatment day. The diffusion coefficient (D), perfusion fraction (f), and pseudo-diffusion coefficient (D*) were calculated based on signal intensities in the non-cancerous prostate, as well as the tumor. Overall, they analyzed 726 fractions.
According to the results, the repeatability coefficients for D, f, and D* in the non-cancerous prostate were 0.09 × 10-3 mm2/s, 0.05, and 15.3 × 10-3 mm2/s, respectively. In the tumor, the researchers observed levels were 0.44 × 10-3 mm2/s, 0.16, and 76.4 × 10-3 mm2/s, respectively. They noted that a mixed effects analysis showed an increase in D of the tumors over the course of treatment, while remaining stable in the non-cancerous prostate. The f and D* increased in both the non-cancerous prostate and tumor, the researchers further noted.
“It is feasible to perform daily IVIM measurements on an MR-linac system. Although the repeatability coefficients were high, changes in IVIM perfusion parameters were measured on a group level, indicating that IVIM has potential for measuring treatment response,” the researchers concluded.