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Purpose: To verify the effectiveness of artificial intelligence-assisted volume isotropic simultaneous interleaved bright-/black-blood examination (AI-VISIBLE) for detecting brain metastases., Methods: This retrospective study was approved by our institutional review board and the requirement for written informed consent was waived. Forty patients were included: 20 patients with and without brain metastases each. Seven independent observers (three radiology residents and four neuroradiologists) participated in two reading sessions: in the first, brain metastases were detected using VISIBLE only; in the second, the results of the first session were comprehensively evaluated by adding AI-VISIBLE information. Sensitivity, diagnostic performance, and false positives/case were evaluated. Diagnostic performance was assessed using a figure-of-merit (FOM). Sensitivity and false positives/case were evaluated using McNemar and paired t-tests, respectively., Results: The McNemar test revealed a significant difference between VISIBLE with/without AI information (P < 0.0001). Significantly higher sensitivity (94.9 ± 1.7% vs. 88.3 ± 5.1%, P = 0.0028) and FOM (0.983 ± 0.009 vs. 0.972 ± 0.013, P = 0.0063) were achieved using VISIBLE with AI information vs. without. No significant difference was observed in false positives/case with and without AI information (0.23 ± 0.19 vs. 0.18 ± 0.15, P = 0.250). AI-assisted results of radiology residents became comparable to results of neuroradiologists (sensitivity, FOM: 85.9 ± 3.4% vs. 90.0 ± 5.9%, 0.969 ± 0.016 vs. 0.974 ± 0.012 without AI information; 94.8 ± 1.3% vs. 95.0 ± 2.1%, 0.977 ± 0.010 vs. 0.988 ± 0.005 with AI information, respectively)., Conclusion: AI-VISIBLE improved the sensitivity and performance for diagnosing brain metastases., Competing Interests: Declarations. Ethics approval and consent to participate: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This retrospective study was approved by our Institutional Review Board (Number 24–45). Consent for publication: Not applicable. Competing interests: The authors declare no conflicts of interest related to the content of this article., (© 2024. The Author(s).)

Purpose: This study aimed to compare assessments by radiologists, artificial intelligence (AI), and quantitative measurement using synthetic MRI (SyMRI) for differential diagnosis between astrocytoma, IDH-mutant and oligodendroglioma, and IDH-mutant and 1p/19q-codeleted and to identify the superior method., Methods: Thirty-three cases (men, 14; women, 19) comprising 19 astrocytomas and 14 oligodendrogliomas were evaluated. Four radiologists independently evaluated the presence of the T2-FLAIR mismatch sign. A 3D convolutional neural network (CNN) model was trained using 50 patients outside the test group (28 astrocytomas and 22 oligodendrogliomas) and transferred to evaluate the T2-FLAIR mismatch lesions in the test group. If the CNN labeled more than 50% of the T2-prolonged lesion area, the result was considered positive. The T1/T2-relaxation times and proton density (PD) derived from SyMRI were measured in both gliomas. Each quantitative parameter (T1, T2, and PD) was compared between gliomas using the Mann-Whitney U-test. Receiver-operating characteristic analysis was used to evaluate the diagnostic performance., Results: The mean sensitivity, specificity, and area under the curve (AUC) of radiologists vs. AI were 76.3% vs. 94.7%; 100% vs. 92.9%; and 0.880 vs. 0.938, respectively. The two types of diffuse gliomas could be differentiated using a cutoff value of 2290/128 ms for a combined 90 th percentile of T1 and 10 th percentile of T2 relaxation times with 94.4/100% sensitivity/specificity with an AUC of 0.981., Conclusion: Compared to the radiologists' assessment using the T2-FLAIR mismatch sign, the AI and the SyMRI assessments increased both sensitivity and objectivity, resulting in improved diagnostic performance in differentiating gliomas., (© 2024. The Author(s).)

Purpose: The cortical high-flow sign with the non-enhancing area was reportedly found to be more frequent with oligodendroglioma, IDH-mutant and 1p/19q codeleted (ODG IDHm-codel) than with IDH-wildtype or astrocytoma, IDH-mutant on arterial spin labeling (ASL) in diffuse gliomas. This study aimed to compare the identification rate of the cortical high-flow sign on ASL in patients with ODG IDHm-codel to that on dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI)., Methods: Participants consisted of 32 adult ODG IDHm-codel patients with pathologically confirmed. Subtraction images were generated from paired control and label images on ASL. For DSC, dynamic T2*-weighted perfusion weighted images were obtained after pre-bolus of gadolinium-based contrast agent. Regional cerebral blood flow/volume maps were generated based on the concentration-time curve and arterial input function. Tumor-affecting cortices without contrast enhancement on conventional MR imaging were targeted. The identification rate of the cortical high-flow sign was compared between ASL and DSC using the Pearson's Chi-Square test., Results: Frequency of the cortical high-flow sign was significantly higher on ASL (18/32, 56.3%; p < 0.001) than on DSC (5/32, 15.6%). All cases with the positive cortical high-flow sign on DSC were identified on ASL., Conclusion: ASL effectively identifies the cortical high-flow sign in ODG IDHm-codel, surpassing DSC in identification rates., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to investigate whether arterial spin labeling (ASL) features allow differentiation of oligodendroglioma, IDH-mutant and 1p/19q-codeleted (IDHm-codel) from diffuse glioma with IDH-wildtype (IDHw) or astrocytoma, IDH-mutant (IDHm-noncodel). Participants comprised 71 adult patients with pathologically confirmed diffuse glioma, classified as IDHw, IDHm-noncodel, or IDHm-codel. Subtraction images were generated from paired-control/label images on ASL and used to assess the presence of a cortical high-flow sign. The cortical high-flow sign was defined as increased ASL signal intensity within the tumor-affecting cerebral cortex compared with normal-appearing cortex. Regions without contrast enhancement on conventional MR imaging were targeted. The frequency of the cortical high-flow sign on ASL was compared among IDHw, IDHm-noncodel, and IDHm-codel. As a result, the frequency of the cortical high-flow sign was significantly higher for IDHm-codel than for IDHw or IDHm-noncodel. In conclusion, the cortical high-flow sign could represent a hallmark of oligodendroglioma, IDH-mutant, and 1p/19q-codeleted without intense contrast enhancement., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Isocitrate dehydrogenase (IDH)-wildtype diffuse astrocytic glioma with telomerase reverse transcriptase (TERT) promoter mutation is defined as glioblastoma by the WHO 2021 criteria, revealing that TERT promotor mutation is highly associated with tumor aggressiveness. The aim of this study was to identify features from MR spectroscopy (MRS) and multi-exponential models of DWI distinguishing wild-type TERT (TERTw) from TERT promoter mutation (TERTm) in IDH-wildtype diffuse astrocytic glioma., Methods: Participants comprised 25 adult patients with IDH-wildtype diffuse astrocytic glioma. Participants were classified into TERTw and TERTm groups. Point-resolved spectroscopy sequences were used for MRS data acquisition. DWI was performed with 13 different b-factors. Peak height ratios of NAA/Cr and Cho/Cr were calculated from MRS data. Mean apparent diffusion coefficient (ADC), perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient (D*), distributed diffusion coefficient (DDC), and heterogeneity index (α) were obtained using multi-exponential models from DWI data. Each parameter was compared between TERTw and TERTm using the Mann-Whitney U test. Correlations between parameters derived from MRS and DWI were also evaluated., Results: NAA/Cr and Cho/Cr were both higher for TERTw than for TERTm. The α of TERTw was smaller than that of TERTm, while the f of TERTw was higher than that of TERTm. NAA/Cr correlated negatively with α, but not with other DWI parameters. Cho/Cr did not show significant correlations with any DWI parameters., Conclusion: The combination of NAA/Cr and α may have merit in clinical situation to predict the TERT mutation status of IDH-wildtype diffuse astrocytic glioma without intense enhancement., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Accurate assessment of cerebral perfusion in moyamoya disease is necessary to determine the indication for treatment. We aimed to investigate the usefulness of dynamic PCASL using a variable TR scheme with optimized background suppression in the evaluation of cerebral perfusion in moyamoya disease., Methods: We retrospectively analyzed the images of 24 patients (6 men and 18 women, mean age 31.4 ± 18.2 years) with moyamoya disease; each of whom was imaged with both dynamic PCASL using the variable-TR scheme and 123 IMP SPECT with acetazolamide challenge. ASL dynamic data at 10 phases are acquired by changing the LD and PLD. The background suppression timing was optimized for each phase. CBF and ATT were measured with ASL, and CBF and CVR to an acetazolamide challenge were measured with SPECT., Results: A significant moderate correlation was found between the CBF measured by dynamic PCASL and that by SPECT (r = 0.53, P < 0.001). The CBF measured by dynamic PCASL (52.5 ± 13.3 ml/100 mg/min) was significantly higher than that measured by SPECT (43.0 ± 12.6 ml/100 mg/min, P < 0.001). The ATT measured by dynamic PCASL showed a significant correlation with the CVR measured by SPECT (r = 0.44, P < 0.001). ATT was significantly longer in areas where the CVR was impaired (CVR < 18.4%, ATT = 1812 ± 353 ms) than in areas where it was preserved (CVR > 18.4%, ATT = 1301 ± 437 ms, P < 0.001). The ROC analysis showed a moderate accuracy (AUC = 0.807, sensitivity = 87.7%, specificity = 70.4%) when the cutoff value of ATT was set at 1518 ms., Conclusion: Dynamic PCASL using this scheme was found to be useful for assessing cerebral perfusion in moyamoya disease., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Diffusion-weighted imaging (DWI) plays an important role in the preoperative assessment of gliomas; however, the diagnostic performance of histogram-derived parameters from mono-, bi-, and stretched-exponential DWI models in the grading of gliomas has not been fully investigated. Therefore, we compared these models' ability to differentiate between high-grade and low-grade gliomas., Methods: This retrospective study included 22 patients with diffuse gliomas (age, 23-74 years; 12 males; 11 high-grade and 11 low-grade gliomas) who underwent preoperative 3 T-magnetic resonance imaging from October 2014 to August 2019. The apparent diffusion coefficient was calculated from the mono-exponential model. Using 13 b-values, the true-diffusion coefficient, pseudo-diffusion coefficient, and perfusion fraction were obtained from the bi-exponential model, and the distributed-diffusion coefficient and heterogeneity index were obtained from the stretched-exponential model. Region-of-interests were drawn on each imaging parameter map for subsequent histogram analyses., Results: The skewness of the apparent diffusion, true-diffusion, and distributed-diffusion coefficients was significantly higher in high-grade than in low-grade gliomas (0.67 ± 0.67 vs. - 0.18 ± 0.63, 0.68 ± 0.74 vs. - 0.08 ± 0.66, 0.63 ± 0.72 vs. - 0.15 ± 0.73; P = 0.0066, 0.0192, and 0.0128, respectively). The 10th percentile of the heterogeneity index was significantly lower (0.77 ± 0.08 vs. 0.88 ± 0.04; P = 0.0004), and the 90th percentile of the perfusion fraction was significantly higher (12.64 ± 3.44 vs. 7.14 ± 1.70%: P < 0.0001), in high-grade than in low-grade gliomas. The combination of the 10th percentile of the true-diffusion coefficient and 90th percentile of the perfusion fraction showed the best area under the receiver operating characteristic curve (0.96)., Conclusion: The bi-exponential model exhibited the best diagnostic performance for differentiating high-grade from low-grade gliomas.

Purpose: To evaluate the performance of acceleration-selective arterial spin labeling (AccASL) MR angiography in the visualization of brain arteriovenous malformations (AVMs) in comparison with digital subtraction angiography (DSA) and time-of-flight (TOF) MR angiography., Methods: Twenty-one patients with brain AVM (mean age 31.1 ± 18.6 years; 11 males, 10 females) underwent TOF and AccASL MR angiography and DSA. Two neuroradiologists conducted an observer study for detection, nidus size, eloquence, venous drainage pattern, and Spetzler-Martin (SM) grade. The evaluations included the visualization of each AVM component with reference to DSA and assessments of contrast-to-noise ratio (CNR). The kappa statistic, repeated measures analysis of variance, Wilcoxon matched pairs test, and paired t test were used., Results: Both observers detected more AVMs with AccASL (95.2%, 90.5% for Observers 1 and 2) than with TOF (76.2% and 71.4%, respectively). The inter-modality agreement between AccASL and DSA was almost perfect for the eloquence, venous drainage pattern, and SM grade for Observer 1 and moderate for the venous drainage pattern and substantial for the eloquence and SM grade for Observer 2. The visualization scores were higher with AccASL than with TOF for the feeding artery (AccASL, 4.5 ± 1.0 vs. TOF, 3.9 ± 1.5, p = 0.0214), nidus (4.6 ± 1.1 vs. 3.2 ± 1.5, p = 0.0006), and draining vein (4.6 ± 1.0 vs. 2.2 ± 1.1, p < 0.0001), respectively. The CNRs in the nidus were higher in AccASL than in TOF (29.9 ± 16.7 vs. 20.8 ± 16.5, p = 0.0002), as in the draining vein (23.2 ± 13.0 vs. 12.6 ± 12.0, p = 0.0010), respectively., Conclusions: AccASL better visualized brain AVMs compared with TOF and was useful for grading without the use of contrast agents.

Purpose: Imaging findings of pilocytic astrocytoma (PA) vary widely, sometimes resembling those of high-grade glioma (HGG). This study aimed to identify the imaging parameters that can be used to differentiate PA from HGG., Methods: Altogether, 60 patients with PAs and 138 patients with HGGs were included in the study. Tumor properties and the presence of hydrocephalus, peritumoral edema, and dissemination were evaluated. We also measured the maximum relative cerebral blood flow (rCBF max ) and volume (rCBV max ) and determined the minimum apparent diffusion coefficient (ADC min ) in the tumor's solid components. The relative T1 (rT1), T2 (rT2), and contrast-enhanced T1 (rCE-T1) intensity values were evaluated. Parameters were compared between PAs and HGGs using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was also used to evaluate these imaging parameters. A value of P < .05 was considered to indicate significance., Results: Intratumoral hemorrhage and calcification were observed in 10.0% and 21.7% of PAs, respectively. The rCBF max and rCBV max values were significantly lower in PAs (0.50 ± 0.35, 1.82 ± 1.21) than those in HGGs (2.98 ± 1.80, 9.54 ± 6.88) (P < .0001, P = .0002, respectively). The ADC min values were significantly higher in PAs (1.36 ± 0.56 × 10 -3  mm 2 /s) than those in HGGs (0.86 ± 0.37 × 10 -3  mm 2 /s) (P < .0001). ROC analysis showed that the best diagnostic performance was achieved with rCBF max ., Conclusion: The rCBF max , rCBV max , and ADC min can differentiate PAs from HGGs.

Introduction: Our purpose was to evaluate the diagnostic performance of arterial spin labeling (ASL) perfusion imaging, diffusion-weighted imaging (DWI), and (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) in differentiating primary central nervous system lymphomas (PCNSLs) from glioblastoma multiformes (GBMs)., Methods: Fifty-six patients including 19 with PCNSL and 37 with GBM were retrospectively studied. From the ASL data, an absolute tumor blood flow (aTBF) and a relative tumor blood flow (rTBF) were obtained within the enhancing portion of each tumor. In addition, the minimum apparent diffusion coefficient (ADCmin) and the maximum standard uptake value (SUVmax) were obtained from DWI and FDG-PET data, respectively. Each of the four parameters was compared between PCNSLs and GBMs using Kruskal-Wallis test. The performance in discriminating between PCNSLs and GBMs was evaluated using the receiver-operating characteristics analysis. Area-under-the-curve (AUC) values were compared among the four parameters using a nonparametric method., Results: The aTBF, rTBF, and ADCmin were significantly higher in GBMs (mean aTBF ± SD = 91.6 ± 56.0 mL/100 g/min, mean rTBF ± SD = 2.61 ± 1.61, mean ADCmin ± SD = 0.78 ± 0.19 × 10(-3) mm(2)/s) than in PCNSLs (mean aTBF ± SD = 37.3 ± 10.5 mL/100 g/min, mean rTBF ± SD = 1.24 ± 0.37, mean ADCmin ± SD = 0.61 ± 0.13 × 10(-3) mm(2)/s) (p < 0.005, respectively). In addition, SUVmax was significantly lower in GBMs (mean ± SD = 13.1 ± 6.34) than in PCNSLs (mean ± SD = 22.5 ± 7.83) (p < 0.005). The AUC for aTBF (0.888) was higher than those for rTBF (0.810), ADCmin (0.768), and SUVmax (0.848), although their difference was not statistically significant., Conclusion: ASL perfusion imaging is useful for differentiating PCNSLs from GBMs as well as DWI and FDG-PET.

Introduction: Hemangioblastoma and metastatic tumors are the major differential diagnoses for the posterior fossa tumors in adults. Our purpose was to evaluate the efficacy of ASL in differentiating hemangioblastomas from metastatic brain tumors., Methods: A total of 19 patients including 5 with a hemangioblastomas and 14 with metastatic tumors (7 from lung cancer, 4 from breast cancer, 1 from RCC, 1 from gastric cancer, and 1 from unknown origin) were enrolled in this study. ASL was performed using a pulsed ASL method at a 3-T unit. aTBF was measured as a mean absolute blood flow value within a region of interest drawn in the tumor. In addition, rTBF was obtained by normalizing the aTBF by a blood flow measured in the normal-appearing cortical gray matter. The aTBF and rTBF values were compared between hemangioblastomas and metastatic tumors using Student's t test., Results: Both the aTBF and rTBF values were significantly higher in hemangioblastomas (mean aTBF ± SD = 437 ± 274 mL/100 g/min, mean rTBF ± SD = 7.96 ± 3.12) in comparison with metastatic brain tumors (mean aTBF ± SD = 125 ± 134 mL/100 g/min, mean rTBF ± SD = 2.98 ± 3.91; p < 0.05, respectively). However, a metastasis from RCC showed very high aTBF (559 mL/100 g/min) and rTBF (16.2)., Conclusion: Our results demonstrated that ASL provides useful information to differentiate between hemangioblastomas and metastatic brain tumors. Metastasis from RCC may mimic hemangioblastoma on ASL blood flow measurement.