Reproducible imaging-based prediction of molecular subtype and risk stratification of gliomas across different experience levels using a structured reporting system

Abstract

Objectives To determine reproducible MRI parameters predictive of molecular subtype and risk stratification in glioma and develop a structured reporting system. Methods All study patients were initially diagnosed with glioma, 141 from the Cancer Genome Atlas and 131 from our tertiary institution, as training and validation sets, respectively. Images were analyzed by three neuroradiologists with 1-7 years of experience. MRI features including contrast enhancement pattern, necrosis, margin, edema, T2/FLAIR mismatch, internal cyst, and cerebral blood volume higher than normal cortex were reported using a structured reporting system. The pathology was stratified into five risk types: (1) oligodendroglioma, isocitrate dehydrogenase [IDH]-mutant, 1p19q co-deleted; (2) diffuse astrocytoma, IDH-mutant, grade II-III; (3) glioblastoma, IDH-mutant, grade IV; (4) diffuse astrocytoma, IDH-wild, grade II-III; and (5) glioblastoma, IDH-wild, grade IV. Significant predictors were selected using multivariate logistic regression, and diagnostic performance was tested using a validation set. Results Reproducible imaging parameters exhibiting > 50% agreement across readers included the presence of necrosis, T2/ FLAIR mismatch, internal cyst, and predominant contrast enhancement. In the validation set, prediction of risk type 5 exhibited the highest diagnostic performance with AUCs of 0.92 (reader 1) and 0.93 (reader 2) with predominant enhancement, followed by risk type 2 with AUCs of 0.95 and 0.95 with T2/FLAIR mismatch sign and no necrosis, and risk type 1 with AUCs of 0.84 and 0.83 with internal cyst or necrosis. Risk types 3 and 4 were difficult to visually predict. Conclusions Imaging parameters with high reproducibility enabling prediction of IDH-wild-type glioblastoma, IDH-mutant/ 1p19q co-deletion oligodendroglioma, and IDH-mutant diffuse astrocytoma were identified. Key Points• Reproducible MRI parameters for determining molecular subtypes of glioma included the presence of necrosis, T2/FLAIR mismatch, internal cyst, and predominant contrast enhancement. • IDH-wild type glioblastoma, IDH-mutant/1p19q co-deletion oligodendroglioma, and IDH-mutant low-grade astrocytoma were identified using MRI parameters with high inter-reader reproducibility. • Identification of IDH-wild type low-grade glioma and IDH-mutant glioblastoma was difficult by visual analysis.

The 2021 WHO Classification for Gliomas and Implications on Imaging Diagnosis: Part 1—Key Points of the Fifth Edition and Summary of Imaging Findings on Adult‐Type Diffuse Gliomas

“…Typical imaging findings include frontal location (53%–67%), 16,26 cortical involvement, heterogeneous signal on T2‐weighted or FLAIR images, calcification, and presence of cystic changes 14,27–31 . Oligodendrogliomas do demonstrate contrast enhancement, but in only part of the tumor.…”

“…Oligodendrogliomas do demonstrate contrast enhancement, but in only part of the tumor. Specifically, approximately 40%–50% of oligodendrogliomas demonstrate contrast enhancement and it is more common in grade 3 30,32 . On advanced imaging, oligodendrogliomas may show lower ADC value and higher rCBV than astrocytomas, IDH‐mutant, WHO grade 2 or 3, 33 and these imaging findings should not be confused with those of glioblastoma, IDH‐wildtype.…”

“…Typical imaging findings include frontal location (53%-67%), 16,26 cortical involvement, heterogeneous signal on T2-weighted or FLAIR images, calcification, and presence of cystic changes. 14,[27][28][29][30][31] Oligodendrogliomas do demonstrate contrast enhancement, but in only part of the tumor. Specifically, approximately 40%-50% of oligodendrogliomas demonstrate contrast enhancement and it is more common in grade 3.…”

“…Specifically, approximately 40%-50% of oligodendrogliomas demonstrate contrast enhancement and it is more common in grade 3. 30,32 On advanced imaging, oligodendrogliomas may show lower ADC value and higher rCBV than astrocytomas, IDH-mutant, WHO grade 2 or 3, 33 and these imaging findings should not be confused with those of glioblastoma, IDH-wildtype. Figure 6 shows typical imaging features of with oligodendroglioma, IDH-mutant and 1p/19q codeleted, according to different WHO grades.…”

Beyond invasive biopsies: using VASARI MRI features to predict grade and molecular parameters in gliomas

“…The VASARI features encompass various aspects of the tumor, including its location, shape, enhancement quality, necrosis proportion, edema proportion, and other geometric properties [ 18 ]. The standardized nature of the VASARI features allows for reproducibility and consistency in the interpretation of MRI scans, enabling interobserver agreement and facilitating multicenter collaborations [ 19 , 20 ]. The use of VASARI features in structured reporting systems improves communication between radiologists, oncologists, and other healthcare professionals involved in the management of glioma patients [ 20 ].…”