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The complementary role of MRI and FET PET in high-grade gliomas to differentiate recurrence from radionecrosis
Arpita Sahu1, Ronny Mathew1, Renuka Ashtekar1
1Department of Radiodiagnosis, Tata Memorial Hospital and Homi Bhabha National Institute, Mumbai, India.
Introduction:
Conventional magnetic resonance imaging (MRI) has limitations in differentiating tumor recurrence (TR) from radionecrosis (RN) in high-grade gliomas (HGG), which can present with morphologically similar appearances. Multiparametric advanced MR sequences and Positron Emission Tomography (PET) with amino acid tracers can aid in diagnosing tumor metabolism. The role of both modalities on an individual basis and combined performances were investigated in the current study.
Materials And Methods:
Patients with HGG with MRI and PET within three weeks were included in the retrospective analysis. The multiparametric MRI included T1-contrast, T2-weighted sequences, perfusion, diffusion, and spectroscopy. MRI was interpreted by a neuroradiologist without using information from PET imaging. 18F-Fluoroethyl-Tyrosine (FET) uptake was calculated from the areas of maximum enhancement/suspicion, which was assessed by a nuclear medicine physician (having access to MRI to determine tumor-to-white matter ratio over a specific region). A definitive diagnosis of TR or RN was made based on the combination of multidisciplinary joint clinic decisions, histopathological examination, and clinic-radiological follow-up as applicable.
Results:
62 patients were included in the study between July 2018 and August 2021. The histology during initial diagnosis was glioblastoma, oligodendroglioma, and astrocytoma in 43, 7, and 6 patients, respectively, while in 6, no definitive histological characterization was available. The median time from radiation (RT) was 23 months. 46 and 16 patients had TR and RN recurrence, respectively. Sensitivity, specificity, and accuracy using MRI were 98, 77, and 94%, respectively. Using PET imaging with T/W cut-off of 2.65, sensitivity, specificity, and accuracy were 79, 84, and 80%, respectively. The best results were obtained using both imaging combined with sensitivity, specificity, and accuracy of 98, 100, and 98%, respectively.
Conclusion:
Combined imaging with MRI and FET-PET offers multiparametric assessment of glioma recurrence that is correlative and complimentary, with higher accuracy and clinical value.
Insights
Combining MRI and FET-PET accurately differentiates high-grade glioma tumor recurrence from radionecrosis. This multiparametric approach offers superior diagnostic performance compared to individual methods, improving clinical decision-making for HGG patients.
Area of Science:
- Neuro-oncology
- Medical imaging
- Radiochemistry
Background:
- Differentiating tumor recurrence (TR) from radionecrosis (RN) in high-grade gliomas (HGG) is challenging with conventional MRI due to similar appearances.
- Advanced multiparametric MRI sequences and amino acid tracer Positron Emission Tomography (PET) show promise in assessing tumor metabolism.
Purpose of the Study:
- To investigate the individual and combined diagnostic performance of multiparametric MRI and 18F-Fluoroethyl-Tyrosine (FET)-PET for differentiating TR from RN in HGG.
- To evaluate the accuracy and clinical value of combined imaging modalities.
Main Methods:
- Retrospective analysis of 62 HGG patients with concurrent MRI and FET-PET scans within three weeks.
- Multiparametric MRI included T1-contrast, T2-weighted, perfusion, diffusion, and spectroscopy sequences.
- 18F-FET uptake was quantified using the tumor-to-white matter ratio, with definitive diagnosis based on multidisciplinary consensus, histology, or follow-up.
Main Results:
- MRI alone showed 98% sensitivity, 77% specificity, and 94% accuracy.
- FET-PET imaging achieved 79% sensitivity, 84% specificity, and 80% accuracy.
- Combined MRI and FET-PET demonstrated superior performance with 98% sensitivity, 100% specificity, and 98% accuracy.
Conclusions:
- Combined multiparametric MRI and FET-PET imaging provide a highly accurate and complementary assessment for glioma recurrence.
- This integrated approach significantly enhances diagnostic confidence and clinical value in managing HGG patients post-treatment.
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