Article
Diffusion-weighted imaging for monitoring the response of malignant gliomas to photodynamic therapy
Diffusionsgewichtete Bildgebung zur Überwachung der Reaktion von malignen Gliomen auf die photodynamische Therapie
Search Medline for
Authors
Published: | June 26, 2020 |
---|
Outline
Text
Objective: Photodynamic therapy (PDT) is a novel treatment that provides effective local control, but little is known about PDT-induced changes on MR imaging. The aim of this study was to access the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) in monitoring the response of malignant gliomas to PDT.
Methods: Time-dependent changes in DWI and ADC values after PDT were analyzed in a group that received PDT in comparison with a group that did not.
Results: Twenty-four patients were enrolled (PDT group, n=14; non-PDT group, n=10). In all patients who received PDT, 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 post-treatment and disappeared in about 30 days without any neurological deterioration. The non-PDT group did not show this change. The PDT group had significantly lower ADC values from 1 day post-treatment (p < 0.001) that increased steadily and disappeared by 30 days. There was no decline or time-dependent change in ADC values in the non-PDT group. Furthermore, only 3 patients in the PDT group exhibited local recurrence during a mean post-treatment follow-up of 17.4 months. All of the local recurrences in the PDT group arose from the non-irradiated area, which did not show a high signal on DWI.
Conclusion: The acute response of malignant gliomas to PDT was detected as linear high signals on DWI and as a decrease in ADC values. These findings were asymptomatic and transient. Although the PDT-induced acute response on MR imaging disappeared after approximately 30 days, it may be helpful for confirming the PDT-irradiated area and predicting the local recurrence site.