Multiparametric MRI and T2/FLAIR mismatch complements the World Health Organization 2021 classification for the diagnosis of IDH-mutant 1p/19q non-co-deleted/ATRX-mutant astrocytoma.

AIM: To investigate whether T2-weighted imaging-fluid-attenuated inversion recovery (T2/FLAIR) mismatch, T2∗ dynamic susceptibility contrast (DSC) perfusion, and magnetic resonance spectroscopy (MRS) correlated with the histological diagnosis and grading of IDH (isocitrate dehydrogenase)-mutant, 1p/19q non-co-deleted/ATRX (alpha-thalassemia mental retardation X-linked)-mutant astrocytoma. MATERIALS: Imaging of 101 IDH-mutant diffuse glioma cases of histological grades 2-3 (2019-2021) were analysed retrospectively by two neuroradiologists blinded to the molecular diagnosis. T2/FLAIR mismatch sign is used for radio-phenotyping, and pre-biopsy multiparametric MRI images were assessed for grading purposes. Cut-off values pre-determined for radiologically high-grade lesions were relative cerebral blood volume (rCBV) ≥2, choline/creatine ratio (Cho/Cr) ≥1.5 (30 ms echo time [TE]), Cho/Cr ≥1.8 (135 ms TE). RESULTS: Sixteen of the 101 cases showed T2/FLAIR mismatch, all of which were histogenetically confirmed IDH-mutant 1p/19q non-co-deleted/ATRX mutant astrocytomas; 50% were grade 3 (8/16) and 50% grade 2 (8/16). None showed contrast enhancement. Nine of the 16 had adequate multiparametric MRI for analysis. Any positive value by combining rCBV ≥2 with Cho/Cr ≥1.5 (30 ms TE) or Cho/Cr ≥1.8 (135 ms TE) predicted grade 3 histology with sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 100%. CONCLUSION: The T2/FLAIR mismatch sign detected diffuse astrocytomas with 100% specificity. When combined with high Cho/Cr and raised rCBV, this predicted histological grading with high accuracy. The future direction for imaging should explore a similar integrated layered approach of 2021 classification of central nervous system (CNS) tumours combining radio-phenotyping and grading from structural and multiparametric imaging.

COVID-19-related intracranial imaging findings: a large single-centre experience.

AIM: To describe the neuroradiological changes in patients with coronavirus disease 2019 (COVID-19). MATERIALS AND METHODS: A retrospective review was undertaken of 3,403 patients who were confirmed positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and admitted to Queen Elizabeth Hospital Birmingham, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK between 1 March 2020 and 31 May 2020, and who underwent neuroimaging. Abnormal brain imaging was evaluated in detail and various imaging patterns on magnetic resonance imaging MRI were identified. RESULTS: Of the 3,403 patients with COVID-19, 167 (4.9%) had neurological signs or symptoms warranting neuroimaging. The most common indications were delirium (44/167, 26%), focal neurology (37/167, 22%), and altered consciousness (34/167, 20%). Neuroimaging showed abnormalities in 23% of patients, with MRI being abnormal in 20 patients and computed tomography (CT) in 18 patients. The most consistent neuroradiological finding was microhaemorrhage with a predilection for the splenium of the corpus callosum (12/20, 60%) followed by acute or subacute infarct (5/20, 25%), watershed white matter hyperintensities (4/20, 20%), and susceptibility changes on susceptibility-weighted imaging (SWI) in the superficial veins (3/20, 15%), acute haemorrhagic necrotising encephalopathy (2/20, 10%), large parenchymal haemorrhage (2/20, 10%), subarachnoid haemorrhage (1/20, 5%), hypoxic-ischaemic changes (1/20, 5%), and acute disseminated encephalomyelitis (ADEM)-like changes (1/20, 5%). CONCLUSION: Various imaging patterns on MRI were observed including acute haemorrhagic necrotising encephalopathy, white matter hyperintensities, hypoxic-ischaemic changes, ADEM-like changes, and stroke. Microhaemorrhages were the most common findings. Prolonged hypoxaemia, consumption coagulopathy, and endothelial disruption are the likely pathological drivers and reflect disease severity in this patient cohort.