Evaluation of isocitrate dehydrogenase mutation in 2021 world health organization classification grade 3 and 4 glioma adult-type diffuse gliomas with 18F-fluoromisonidazole PET.

PURPOSE: This study aimed to investigate the uptake characteristics of 18F-fluoromisonidazole (FMISO), in mutant-type isocitrate dehydrogenase (IDH-mutant, grade 3 and 4) and wild-type IDH (IDH-wildtype, grade 4) 2021 WHO classification adult-type diffuse gliomas. MATERIALS AND METHODS: Patients with grade 3 and 4 adult-type diffuse gliomas (n = 35) were included in this prospective study. After registering 18F-FMISO PET and MR images, standardized uptake value (SUV) and apparent diffusion coefficient (ADC) were evaluated in hyperintense areas on fluid-attenuated inversion recovery (FLAIR) imaging (HIA), and in contrast-enhanced tumors (CET) by manually placing 3D volumes of interest. Relative SUVmax (rSUVmax) and SUVmean (rSUVmean), 10th percentile of ADC (ADC10pct), mean ADC (ADCmean) were measured in HIA and CET, respectively. RESULTS: rSUVmean in HIA and rSUVmean in CET were significantly higher in IDH-wildtype than in IDH-mutant (P = 0.0496 and 0.03, respectively). The combination of FMISO rSUVmean in HIA and ADC10pct in CET, that of rSUVmax and ADC10pct in CET, that of rSUVmean in HIA and ADCmean in CET, were able to differentiate IDH-mutant from IDH-wildtype (AUC 0.80). When confined to astrocytic tumors except for oligodendroglioma, rSUVmax, rSUVmean in HIA and rSUVmean in CET were higher for IDH-wildtype than for IDH-mutant, but not significantly (P = 0.23, 0.13 and 0.14, respectively). The combination of FMISO rSUVmean in HIA and ADC10pct in CET was able to differentiate IDH-mutant (AUC 0.81). CONCLUSION: PET using 18F-FMISO and ADC might provide a valuable tool for differentiating between IDH mutation status of 2021 WHO classification grade 3 and 4 adult-type diffuse gliomas.

Telomerase reverse transcriptase promoter mutation and histologic grade in IDH wild-type histological lower-grade gliomas: The value of perfusion-weighted image, diffusion-weighted image, and 18F-FDG-PET.

PURPOSE: The telomerase reverse transcriptase promoter (TERTp) mutation is an unfavorable prognostic factor in isocitrate dehydrogenase-wildtype (IDHwt) histologically lower-grade astrocytoma (LGA), which was incorporated as a key component in the WHO 2021 classification of IDHwt LGA, replacing histologic grades in the WHO 2016 classification. The purpose of this study was to identify the imaging characteristics predictive of TERTp mutations in IDHwt LGA. METHODS: This retrospective study was approved by our institutional review board. This single-center study retrospectively included 59 patients with pathologically confirmed IDHwt LGA with known TERTp mutation status. In addition to clinical information and morphological characteristics, semi-quantitative imaging biomarkers such as the tumor-to-normal ratio (T/N ratio) on 18F-FDG-PET, normalized apparent diffusion coefficient (nADC), and histogram parameters from normalized relative cerebral blood volume (nrCBV) maps were compared between (a) TERTp-wildtype and TERTp-mutant tumors or (b) grade II and grade III astrocytoma. A p value < 0.05 was considered significant. RESULTS: There were no significant differences in the conventional imaging findings, T/N ratio on FDG-PET, nrCBV or ADC histogram metrics between IDHwt LGA with TERTp mutations and those without. Grade III IDHwt astrocytomas exhibited significantly higher nrCBV values, T/N ratio and lower ADC parameters than grade II IDHwt astrocytoma. CONCLUSIONS: In patients with IDHwt LGA, T/N ratio, nrCBV values and nADC may be surrogate markers for predicting histologic grade, but are not useful for predicting TERTp mutations.

Evaluation of moyamoya disease in CT angiography using ultra-high-resolution computed tomography: Application of deep learning reconstruction.

PURPOSE: The aim of this study was to examine the evaluation of ultra-high-resolution computed tomography angiography (UHR CTA) images in moyamoya disease (MMD) reconstructed with hybrid iterative reconstruction (Hybrid-IR), model-based iterative reconstruction (MBIR), and deep learning reconstruction (DLR). METHODS: This retrospective study with institutional review board approval included patients with clinically suspected MMD who underwent UHR CTA between January 2018 and July 2020. CTA images were reconstructed with three reconstruction methods. Qualitative visualization was evaluated in comparison with digital subtraction angiography. Quantitative evaluation included assessment of edge sharpness, full width at half maximum (FWHM), vessel contrast, and tissue signal-to-noise ratio (SNRtissue). One-way analysis of variance was used to analyze differences. In addition, reconstruction time were assessed. RESULTS: Qualitative evaluation of CTA for 33 sides did not differ significantly between reconstruction methods. In quantitative evaluation for 54 patients, edge sharpness for right and left cortical segments of the middle cerebral artery was significantly higher for Hybrid-IR than for other reconstructions. No significant difference was seen between MBIR and DLR. Edge sharpness for STA-MCA bypass was significantly higher for Hybrid-IR than for MBIR, but no significant difference was seen between Hybrid-IR and DLR. FWHM for STA-MCA showed no significant difference between the three reconstruction methods. DLR displayed the highest SNRtissue. The time required for reconstruction was 40 s for Hybrid-IR, 2580 s for MBIR, and 180 s for DLR. CONCLUSION: UHR CTA with DLR adequately visualized vessels in patients with MMD within a clinically feasible reconstruction time.

Patient characteristics with negative diffusion-weighted imaging findings in acute lateral medullary infarction.

BACKGROUND: Diffusion-weighted imaging (DWI) on magnetic resonance imaging (MRI) shows limited sensitivity in the acute-phase brainstem infarctions, including lateral medullary infarction (LMI), and the detailed characteristics of acute LMI patients with initially negative DWI-MRI findings have not been reported previously. Therefore, we aimed to investigate the differences in the backgrounds or symptoms of acute LMI patients with initially negative findings in standard axial DWI-MRI and those with positive findings. METHODS: In this retrospective cohort study, we collected the data for 35 consecutive acute LMI patients who were hospitalized in our hospital from January 2011 to December 2018. Initial standard axial DWI-MRI was assessed, and the patients were divided into positive and negative groups. The characteristics of the two groups were compared, and the usefulness of additional thin-slice coronal DWI-MRI was also investigated. RESULTS: Nine (26%) acute LMI patients were initially negative on standard axial DWI-MRI. The patients were independently associated with smoking history (78% vs. 23%, p = 0.021) and headache (78% vs. 31%, p = 0.046). Thin-slice coronal DWI-MRI showed positive findings in 50% of the patients with negative findings in standard axial DWI-MRI. All four patients with negative findings in both standard axial and thin-slice coronal DWI-MRI had smoking history and headache. CONCLUSION: Smoking history and headache were associated with initial negative results in standard axial DWI-MRI in acute LMI. Additional thin-slice coronal DWI-MRI was sometimes useful in detecting acute LMI. Follow-up MRI is important for patients showing negative findings in initial DWI-MRI.

Multiple Cerebral Hemorrhages With Microbleeds in Intravascular Large B-Cell Lymphoma.

This is an extremely rare reported case of intravascular large B-cell lymphoma (IVLBCL) presenting with acute hemorrhages and numerous microbleeds. An 80-year-old man presented with consciousness disturbances after convulsion. Computed tomography revealed multiple hemorrhages, and susceptibility-weighted imaging (SWI) demonstrated numerous microbleeds. Brain biopsy showed CD20-positive cells in small vessels; accordingly, IVLBCL was diagnosed. IVLBCL should be considered as a differential diagnosis in multiple cerebral hemorrhages and microbleeds.

Quantitative assessment of gadolinium deposition in dentate nucleus using quantitative susceptibility mapping.

PURPOSE: Gadolinium deposition in dentate nucleus (DN) has been reported after serial administration of gadolinium-based contrast agents (GBCAs). Gadolinium complexes have paramagnetic properties; therefore, we evaluated susceptibility changes of gadolinium deposition in DN using quantitative susceptibility mapping (QSM) for patients after serial administration of GBCAs. MATERIALS AND METHODS: In all, 48 patients with brain tumors, who had had serial GBCA administrations (GBCA group), and 48 healthy volunteers without any history of GBCA administrations (non-GBCA group) were enrolled in this study. Susceptibility values in DN on QSM and DN-to-cerebellum signal intensity ratios on unenhanced T1 -weighted images (T1 ratios) on 3T were analyzed. The relationship between the number of times of GBCA administrations and susceptibility values or T1 ratios were evaluated in the GBCA group. RESULTS: Susceptibility values at DN in the GBCA group were 0.107 ± 0.029 ppm, and significantly higher than those of the non-GBCA group (0.079 ± 0.025 ppm) (P < 0.0001). T1 ratios in DN of the GBCA group were 1.059 ± 0.070, and also significantly higher than that of the non-GBCA group (0.993 ± 0.016) (P < 0.0001). Spearman rank correlation coefficients between susceptibility values and the number of times of linear GBCA administration showed a modest significant correlation (ρ = 0.45, P = 0.0015). There was good correlation between T1 ratios and the number of times of linear GBCA administration, as reported previously (ρ = 0.76, P < 0.0001). CONCLUSION: Susceptibility values on QSM in DN of the GBCA group, after serial administration of GBCAs, were significantly higher than those of the non-GBCA group. Evidence Level: 3 J. MAGN. RESON. IMAGING 2017;45:1352-1358.