1. Differential diagnosis between progression and radionecrosis in brain metastases after stereotactic radiosurgery using hybrid FDG-PET and MRI coregistered images
- Author
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E. Le Bars, Florent Cachin, B. Fayçal, M. Chanchou, D. Mariano Goulart, H. Otman, Jeremy Deverdun, François Molino, N. Menjot de Champfleur, and M. Bilal Chawki
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Radiological and Ultrasound Technology ,business.industry ,medicine.medical_treatment ,Significant difference ,Biophysics ,Brain tumor ,Normal tissue ,medicine.disease ,Radiosurgery ,030218 nuclear medicine & medical imaging ,Lesion ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Stereotaxic radiosurgery ,Radiology, Nuclear Medicine and imaging ,Differential diagnosis ,medicine.symptom ,business ,Nuclear medicine ,Perfusion - Abstract
Introduction Dual phase 18 FDG brain PET is helpful to assess brain metastases (BM) as tracer will build up in metastases or tumor recurrences while its retention remains stable within normal tissue or inflammatory processes. This is useful when MRI can’t discriminate brain tumor recurrence (TR) rom radionecrosis (RN) after stereotaxic radiosurgery (SRS) for BM. Many studies have sought to improve diagnostic performance by associating FDG-PET and MRI with interesting results but many biases, mostly within image post-processing. Coregistered MRI and dual phase FDG-PET images could alleviate these biases and be used to extract prognostic biomarkers. Materials and methods We retrospectively evaluated patients treated with SRS for BM which developed a contrast-enhanced MRI lesion with non-conclusive diagnosis for TR or RN. All patients underwent MRI and FDG-PET at least 3 months after their last SRS session. Dual FDG-PET consisted in an “early” and “delayed” acquisition, respectively 30 minutes and 4 h after injection. MRI included permeability and perfusion sequences. PET and MRI data were all coregistered on the contrast enhanced T1 MRI images. Semi-automated Volumes of Interest (VOI) of the tumor were drawn on the BM and a reference contralateral white-matter ROI (WM) was drawn for standardization; every metric was calculated inside these ROIs, in particular the tumor SUVmax and its variation in time. A 20% increase in the tumor SUVmax was in favor of TR while a modification of less than 100% was in favor of RN. Imaging metrics were then evaluated for their association with TR or RN based on histological, radiological and clinical criteria after at least 6 months follow-up. Results Nine patients were ruled out as TR and 6 as RN. After standardization, there was a significant difference between groups for VP (P = 0.042), Washin (P = 0.035), Peak Enhancement (P = 0.037), standardized delayed SUVmax (P = 0.008) and RI (P = 0.016). Semi-quantitative analysis found respectively for PET and MRI a Sensitivity of 100% and 87.5% and a Specificity of 100% and 85.71%. Conclusion Coregistered PET-MRI images accurately discriminate between TR and RN. With FDG being the most commonly used PET radiotracer, this protocol remains easily transposable and should be encouraged to obtain non-invasive prognostic and clinically relevant biomarkers.
- Published
- 2021
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