DWI for Monitoring the Acute Response of Malignant Gliomas to Photodynamic Therapy

• Published in: American journal of neuroradiology : AJNR Vol. 40; no. 12; pp. 2045 - 2051
• Main Authors: Fujita, Y, Sasayama, T, Tanaka, K, Kyotani, K, Nagashima, H, Kohta, M, Kimura, H, Fujita, A, Kohmura, E
• Format: Journal Article
• Language: English
• Published: United States American Society of Neuroradiology 01.12.2019
• Subjects: Adult Brain
• ISSN: 0195-6108; 1936-959X
• DOI: 10.3174/ajnr.a6300

Photodynamic therapy is a novel treatment that provides effective local control, but little is known about photodynamic therapy-induced changes on MR imaging. The aim of this study was to assess the utility of DWI and ADC in monitoring the response of malignant gliomas to photodynamic therapy. Time-dependent changes in DWI and ADC values after photodynamic therapy were analyzed in a group that received photodynamic therapy in comparison with a group that did not. Twenty-four patients were enrolled (photodynamic therapy,  = 14; non-photodynamic therapy,  = 10). In all patients who received photodynamic therapy, linear high signals on DWI in the irradiated area were detected adjacent to the resection cavity and were 5-7 mm in depth from 1 day posttreatment and disappeared in about 30 days without any neurologic deterioration. The non-photodynamic therapy group did not show this change. The photodynamic therapy group had significantly lower ADC values from 1 day posttreatment ( < .001), which increased steadily and disappeared by 30 days. There was no decline or time-dependent change in ADC values in the non-photodynamic therapy group. The acute response of malignant gliomas to photodynamic therapy was detected as linear high signals on DWI and as a decrease in ADC values. These findings were asymptomatic and transient. Although the photodynamic therapy-induced acute response on MR imaging disappeared after approximately 30 days, it may be helpful for confirming the photodynamic therapy-irradiated area.