Clinicopathological analysis of T2-FLAIR mismatch sign in lower-grade gliomas

Abstract

T2-FLAIR mismatch sign is known as a highly specific imaging marker of IDH-mutant astrocytomas. This study was intended to clarify what the T2-FLAIR mismatch sign represents by pathological analysis of lower-grade gliomas rediagnosed in accordance with the WHO 2016 classification. We retrospectively analyzed the records of 64 patients diagnosed with WHO grade II and III diffuse gliomas between June 2009 and November 2018. T2-FLAIR mismatch sign was found in 10 (45%) out of 22 patients with IDH-mutant astrocytoma, 1 (5%) out of 20 with oligodendroglioma, and 1 (5%) out of 22 with IDH-wild-type astrocytoma. T2-FLAIR mismatch sign as a marker of IDH-mutant astrocytomas showed positive predictive value of 83%. Among 22 patients with IDH-mutant astrocytomas, microcystic change was found in eight, of which seven showed T2-FLAIR mismatch sign. Microcystic change was significantly associated with T2-FLAIR mismatch sign (P < 0.01). From multi-sampling in a patient, abundant microcysts were observed upon HE staining of specimens from the T2-FLAIR mismatched region, while microcysts were hardly observed from the T2-FLAIR matched one. All three protoplasmic astrocytomas among our IDH-mutant astrocytomas presented T2-FLAIR mismatch sign. In conclusion, T2-FLAIR mismatch sign may reflect microcyst formation in IDH-mutant astrocytomas and be common in IDH-mutant protoplasmic astrocytoma.

Quantitative Relaxometry using Synthetic MRI Could be Better than Qualitative T2-FLAIR Mismatch Sign: A Pilot Study

“…Since T2-FLAIR mismatch occurs based on the long T1-relaxation time, the intratumoral cystic component simulates a T2-FLAIR mismatch. The T2-FLAIR mismatch false positive results have been reported in previous studies [15,17]. Therefore, surgical specimens are still needed to diagnose gliomas instead of relying on the T2-FLAIR mismatch sign alone.…”

“…Previous studies have reported that the T2-FLAIR mismatch sign has been shown to predict astrocytoma, IDH-mutant with 95-100% speci city [14,15]; however, sensitivity has been low at 46-51% [8, 14, 16]. Inter-rater agreement has been shown to have a wide range of κ = 0.38-0.88 [5,8,14,15].…”

The Role of the T2–FLAIR Mismatch Sign as an Imaging Marker of IDH Status in a Mixed Population of Low- and High-Grade Gliomas

“…The pooled sensitivity and specificity rates were estimated to be as high as 31% and 100%, respectively. Moreover, Deguici et al reported that the T2–FLAIR mismatch sign was found in 45% of the 22 patients with IDH mutant astrocytoma and in only 5% of those with oligodendroglioma or IDH wild-type astrocytoma [ 18 ]. In the latter study, the positive predictive value of the T2–FLAIR mismatch sign was as high as 83% [ 18 ].…”

“…Moreover, Deguici et al reported that the T2–FLAIR mismatch sign was found in 45% of the 22 patients with IDH mutant astrocytoma and in only 5% of those with oligodendroglioma or IDH wild-type astrocytoma [ 18 ]. In the latter study, the positive predictive value of the T2–FLAIR mismatch sign was as high as 83% [ 18 ]. Throckmorton et al claimed that broadening the criteria to include T2-heterogeneous LGG lesions increased the sensitivity of the T2–FLAIR mismatch sign by 30% [ 26 ].…”

“…It actually reflects differences in the relaxation time characteristics of the IDH mutant and IDH wild-type LGG [ 17 ]. A histopathological study showed that the T2-FLAIR mismatch sign might reflect microcyst formation in IDH mutant astrocytomas and could be common in IDH mutant protoplasmic astrocytomas [ 18 ]. Therefore, in the absence of molecular analysis, the use of the T2–FLAIR mismatch sign, along with histologic assessment, could optimize diagnosis [ 15 ].…”