Delayed MRI Response to LITT in Patients Undergoing Immunotherapy. (16th November 2020)

• Record Type: Journal Article
• Authors: Hong, Christopher S; Chiang, Veronica
• Is Part Of: Neurosurgery. Volume 67(2010)Supplement 1
• Publication Date: 2020-11-16
• Subjects: Nervous system -- Surgery -- Periodicals; 617.48005
• DOI: 10.1093/neuros/nyaa447_867
• Languages: English
• ISSNs: 0148-396X

Abstract

Abstract: INTRODUCTION: Laser interstitial thermal therapy (LITT) is an effective treatment for regrowing lesions after previous radiosurgery to brain metastases, typically resulting in decreased perilesional edema within weeks after surgery followed by delayed reduction in lesion size. We have anecdotally observed that patients on immunotherapy (IT) at time of LITT may exhibit a delayed edema resolution response to laser ablation. METHODS: Post-operative imaging for cases of LITT, performed by the senior author between June 2012 and July 2019, for regrowing lesions after prior radiosurgery for brain metastases were retrospectively reviewed. The IT group was defined as any patent receiving IT treatment within 3 months of the date of LITT. Post-operative MRIs obtained at serial time points after surgery (2 weeks, 6 weeks, 3 months, 6 months, and 12 months) were reviewed for treatment response to LITT, defined as a change in surrounding edema on T2 FLAIR images and change of lesion size on T1-weighted post-contrast images. RESULTS: Out of 60 ablated lesions, 22 were in the IT group and 38 were in the non-IT group. There were no differences in distribution of original cancer pathology (IT: 9 melanoma, 8 lung, 5 other, non-IT: 6 melanoma, 20 lung, 12 other; p>0.05). Time to lesion size response on T1-weighted post-contrast MRI neared but did not reach statistical significance between the IT and non-IT groups: median 3.0 versus 2.25 months (HR 1.5, 0.8-2.5, 95% CI, P = .08), respectively. However, time to reduction of perilesional edema on T2-weighted MRI was significantly longer in the IT group, compared to the non-IT group: median 2.25 versus 1.5 months (HR 1.5, 0.9-2.5, 95% CI, P = .04), respectively. CONCLUSION: These data suggest that treatment with IT around the time of LITT may lead to a delayed edema reduction on MRI after LITT. We hypothesize that IT may enhance normal immune-mediated mechanisms thus increasing perilesional inflammation after LITT. Further studies are needed to corroborate our observations and explore the underlying pathophysiology.