The cortical high-flow sign of oligodendroglioma, IDH-mutant and 1p/19q-codeleted: comparison between arterial spin labeling and dynamic susceptibility contrast methods.

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.

Comparison of diagnostic performance of radiologist- and AI-based assessments of T2-FLAIR mismatch sign and quantitative assessment using synthetic MRI in the differential diagnosis between astrocytoma, IDH-mutant and oligodendroglioma, IDH-mutant and 1p/19q-codeleted.

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 90th percentile of T1 and 10th 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.

Functional connectivity between pre-supplementary motor area and inferior parietal lobule associated with impaired motor response inhibition in first-degree relatives of patients with obsessive-compulsive disorder.

Previous studies have suggested that specific fronto-striatal circuits are associated with impaired motor response inhibition in patients with obsessive-compulsive disorder (OCD) and their relatives. However, no study has investigated the underlying resting-state network associated with motor response inhibition in the unaffected first-degree relatives of patients with OCD. We measured motor response inhibition using stop-signal task, and obtained resting-state fMRI in 23 first-degree relatives and 52 healthy control participants. We explored the group differences in the functional network from seed regions-of-interest (ROIs) associated with motor response inhibition abilities. We used the inferior frontal gyrus (IFG) and pre-supplementary motor area (pre-SMA) as seed-ROIs. A significant group difference was observed in functional connectivity between the pre-SMA and inferior parietal lobule. In the relative group, reduced functional connectivity between these areas was associated with a longer stop-signal reaction time. Additionally, relatives showed significantly greater functional connectivity between the IFG and SMA, precentral, and postcentral areas. Our results could provide new insights into the resting-state neural activity of the pre-SMA underlying impaired motor response inhibition of unaffected first-degree relatives. In addition, our results suggested that relatives have an altered connectivity of the sensorimotor region, similar to that of patients with OCD shown in previous literature.

Gyrification of the medial and lateral orbitofrontal cortex in first-degree relatives of patients with obsessive-compulsive disorder.

Gyrification patterns reflect early neurodevelopment and could be highly heritable. While some discrepant results have been reported, the most consistent finding was that patients with obsessive-compulsive disorder showed altered gyrification patterns in the orbitofrontal cortex. Nevertheless, no study has investigated the alterations in gyrification in unaffected first-degree relatives of patients with obsessive-compulsive disorder. We measured local gyrification by the FreeSurfer software in 23 unaffected first-degree relatives of patients with obsessive-compulsive disorder and 52 healthy control participants. We explored differences in the local gyrification index using vertex-wise whole-brain analysis and a region of interest-based approach in the medial and lateral orbitofrontal cortex. There was no significant difference in the local gyrification index between the 2 groups in the vertex-wise whole-brain analysis. Region of interest analyses showed that, compared with healthy controls, first-degree relatives showed significantly reduced local gyrification index in the left medial and lateral orbitofrontal cortex. A negative correlation was observed between the reduced local gyrification index in lateral orbitofrontal cortex and the subclinical anxiety scores of first-degree relatives. Our results showed that first-degree relatives of patients with obsessive-compulsive disorder had an altered local gyrification index in the orbitofrontal cortex. Especially, reduced local gyrification index in lateral orbitofrontal cortex associated with subclinical anxiety symptom could be a potential neurodevelopmental marker for the illness onset.

Arterial Spin Labeling-Based MR Angiography for Cerebrovascular Diseases: Principles and Clinical Applications.

Arterial spin labeling (ASL) is a noninvasive imaging technique that labels the proton spins in arterial blood and uses them as endogenous tracers. Brain perfusion imaging with ASL is becoming increasingly common in clinical practice, and clinical applications of ASL for intracranial magnetic resonance angiography (MRA) have also been demonstrated. Unlike computed tomography (CT) angiography and cerebral angiography, ASL-based MRA does not require contrast agents. ASL-based MRA overcomes most of the disadvantages of time-of-flight (TOF) MRA. Several schemes have been developed for ASL-based MRA; the most common method has been pulsed ASL, but more recently pseudo-continuous ASL, which provides a higher signal-to-noise ratio (SNR), has been used more frequently. New methods that have been developed include direct intracranial labeling methods such as velocity-selective ASL and acceleration-selective ASL. MRA using an extremely short echo time (eg, silent MRA) or ultrashort echo-time (TE) MRA can suppress metal susceptibility artifacts and is ideal for patients with a metallic device implanted in a cerebral vessel. Vessel-selective 4D ASL MRA can provide digital subtraction angiography (DSA)-like images. This review highlights the principles, clinical applications, and characteristics of various ASL-based MRA techniques. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Usefulness of reconstructed images of Gd-enhanced 3D gradient echo sequences with compressed sensing for mandibular cancer diagnosis: comparison with CT images and histopathological findings.

OBJECTIVES: To compare the delineation of mandibular cancer by 3D T1 turbo field echo with compressed SENSE (CS-3D-T1TFE) images and MDCT images, and to compare both sets of images with histopathological findings, as the gold standard, to validate the accuracy and clinical usefulness of CS-3D-T1TFE reconstruction. METHODS: Twenty-four patients with mandibular squamous cell carcinoma (SCC) who underwent MRI including CS-3D-T1TFE and MDCT examinations before surgery were retrospectively included. For both examinations, 0.5-mm-thick coronal plane images and 0.5-mm-thick plane images perpendicular and parallel to the dentition were constructed. Two radiologists rated bone invasion in three categories indexed by cortical bone, cancellous bone, and mandibular canal (MC), and inter-rater agreement was assessed by weighted kappa statistics. In 20 of the 24 patients who underwent surgery, the correlation of bone invasion with the histopathological evaluation by pathologists was assessed using Pearson's correlation coefficient. Soft-tissue invasion was assessed by diagnosing the presence of invasion into the mylohyoid muscle, gingivobuccal fold, and masticator space, and inter-rater agreement was assessed by kappa statistics. RESULTS: The interobserver agreement for bone invasion assessment was almost perfect with CS-3D-T1TFE and substantial with MDCT. The image evaluations by both observers agreed with the pathological evaluations in 15 of the 20 cases, showing high correlation (r > 0.8). CS-3D-T1TFE also showed higher inter-rater agreement than MDCT for all measures of soft-tissue invasion. CONCLUSIONS: CS-3D-T1TFE reconstructed images were clinically useful in accurately depicting the extent of mandibular cancer invasion and potentially solving the problem of lesion overestimation associated with conventional MRI. KEY POINTS: • Reconstructed CS-3D-T1TFE images were useful for the diagnosis of mandibular cancer. • CS-3D-T1TFE images showed higher inter-rater agreement than MDCT and high correlation with pathological findings. • CS-3D-T1TFE images may solve the problem of overestimation of the tumor extent, which has been associated with MRI in the past.

Cortical high-flow sign on arterial spin labeling: a novel biomarker for IDH-mutation and 1p/19q-codeletion status in diffuse gliomas without intense contrast enhancement.

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.

Predicting TERT promoter mutation status using 1H-MR spectroscopy and stretched-exponential model of diffusion-weighted imaging in IDH-wildtype diffuse astrocytic glioma without intense enhancement.

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.

Assessment of cerebral perfusion in moyamoya disease with dynamic pseudo-continuous arterial spin labeling using a variable repetition time scheme with optimized background suppression.

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 123IMP 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.

Increased functional connectivity between presupplementary motor area and inferior frontal gyrus associated with the ability of motor response inhibition in obsessive-compulsive disorder.

Recent evidence suggests that presupplementary motor area (pre-SMA) and inferior frontal gyrus (IFG) play an important role in response inhibition. However, no study has investigated the relationship between these brain networks at resting-state and response inhibition in obsessive-compulsive disorder (OCD). We performed resting-state functional magnetic resonance imaging scans and then measured the response inhibition of 41 medication-free OCD patients and 49 healthy control (HC) participants by using the stop-signal task outside the scanner. We explored the differences between OCD and HC groups in the functional connectivity of pre-SMA and IFG associated with the ability of motor response inhibition. OCD patients showed a longer stop-signal reaction time (SSRT). Compared to HC, OCD patients exhibit different associations between the ability of motor response inhibition and the functional connectivity between pre-SMA and IFG, inferior parietal lobule, dorsal anterior cingulate cortex, insula, and anterior prefrontal cortex. Additional analysis to investigate the functional connectivity difference from the seed ROIs to the whole brain voxels revealed that, compared to HC, OCD exhibited greater functional connectivity between pre-SMA and IFG. Also, this functional connectivity was positively correlated with the SSRT score. These results provide additional insight into the characteristics of the resting-state functional connectivity of the regions belonging to the cortico-striato-thalamo-cortical circuit and the cingulo-opercular salience network, underlying the impaired motor response inhibition of OCD. In particular, we emphasize the importance of altered functional connectivity between pre-SMA and IFG for the pathophysiology of motor response inhibition in OCD.

Review and consensus recommendations on clinical APT-weighted imaging approaches at 3T: Application to brain tumors.

Amide proton transfer-weighted (APTw) MR imaging shows promise as a biomarker of brain tumor status. Currently used APTw MRI pulse sequences and protocols vary substantially among different institutes, and there are no agreed-on standards in the imaging community. Therefore, the results acquired from different research centers are difficult to compare, which hampers uniform clinical application and interpretation. This paper reviews current clinical APTw imaging approaches and provides a rationale for optimized APTw brain tumor imaging at 3 T, including specific recommendations for pulse sequences, acquisition protocols, and data processing methods. We expect that these consensus recommendations will become the first broadly accepted guidelines for APTw imaging of brain tumors on 3 T MRI systems from different vendors. This will allow more medical centers to use the same or comparable APTw MRI techniques for the detection, characterization, and monitoring of brain tumors, enabling multi-center trials in larger patient cohorts and, ultimately, routine clinical use.

Atrophy of the hippocampal CA1 subfield relates to long-term forgetting in focal epilepsy.

OBJECTIVE: The mechanisms underlying accelerated long-term forgetting (ALF) in patients with epilepsy are still under investigation. We examined the contribution of hippocampal subfields and their morphology to long-term memory performance in patients with focal epilepsy. METHODS: We prospectively assessed long-term memory and performed magnetic resonance imaging in 80 patients with focal epilepsy (61 with temporal lobe epilepsy and 19 with extratemporal lobe epilepsy) and 30 healthy controls. The patients also underwent electroencephalography recording. Verbal and visuospatial memory was tested 30 s, 10 min, and 1 week after learning. We assessed the volumes of the whole hippocampus and seven subfields and deformation of the hippocampal shape. The contributions of the hippocampal volumes and shape deformation to long-term forgetting, controlling for confounding factors, including the presence of interictal epileptiform discharges, were assessed by multiple regression analyses. RESULTS: Patients with focal epilepsy had lower intelligence quotients and route recall scores at 10 min than controls. The focal epilepsy group had smaller volumes of both the right and left hippocampal tails than the control group, but there were no statistically significant group differences for the volumes of the whole hippocampus or other hippocampal subfields. Multiple regression analyses showed a significant association between the left CA1 volume and the 1-week story retention (ß = 7.76; Bonferroni-corrected p = 0.044), but this was not found for the whole hippocampus or other subfield volumes. Hippocampal shape analyses revealed that atrophy of the superior-lateral, superior-central, and inferior-medial regions of the left hippocampus, corresponding to CA1 and CA2/3, was associated with the verbal retention rate. SIGNIFICANCE: Our results suggest that atrophy of the hippocampal CA1 region and its associated structures disrupts long-term memory consolidation in focal epilepsy. Neuronal cell loss in specific hippocampal subfields could be a key underlying cause of ALF in patients with epilepsy.

A deep convolutional neural network-based automatic detection of brain metastases with and without blood vessel suppression.

OBJECTIVES: To develop an automated model to detect brain metastases using a convolutional neural network (CNN) and volume isotropic simultaneous interleaved bright-blood and black-blood examination (VISIBLE) and to compare its diagnostic performance with the observer test. METHODS: This retrospective study included patients with clinical suspicion of brain metastases imaged with VISIBLE from March 2016 to July 2019 to create a model. Images with and without blood vessel suppression were used for training an existing CNN (DeepMedic). Diagnostic performance was evaluated using sensitivity and false-positive results per case (FPs/case). We compared the diagnostic performance of the CNN model with that of the twelve radiologists. RESULTS: Fifty patients (30 males and 20 females; age range 29-86 years; mean 63.3 ± 12.8 years; a total of 165 metastases) who were clinically diagnosed with brain metastasis on follow-up were used for the training. The sensitivity of our model was 91.7%, which was higher than that of the observer test (mean ± standard deviation; 88.7 ± 3.7%). The number of FPs/case in our model was 1.5, which was greater than that by the observer test (0.17 ± 0.09). CONCLUSIONS: Compared to radiologists, our model created by VISIBLE and CNN to diagnose brain metastases showed higher sensitivity. The number of FPs/case by our model was greater than that by the observer test of radiologists; however, it was less than that in most of the previous studies with deep learning. KEY POINTS: • Our convolutional neural network based on bright-blood and black-blood examination to diagnose brain metastases showed a higher sensitivity than that by the observer test. • The number of false-positives/case by our model was greater than that by the previous observer test; however, it was less than those from most previous studies. • In our model, false-positives were found in the vessels, choroid plexus, and image noise or unknown causes.

[Central Nervous System Diseases That Are Difficult to Distinguish from Infection].

It is often difficult to distinguish infectious disease of the central nervous system from a wide variety of non-infectious diseases, as neurosurgeons have few opportunities to treat them. Differentiation of infectious diseases from neoplastic diseases is often challenging. Since it often takes time to eliminate infectious diseases, it is necessary to utilize all the obtained medical information to make a proper diagnosis to avoid missing the appropriate chance of surgical treatment. In this paper, we describe tips for and pitfalls of accurately distinguishing such diseases, including brain abscess versus glioblastoma, meningitis versus dural lesions, and infection versus lymphoproliferative disorders in immunocompromised patients. In these cases, it is difficult to make a decision based only on the examination and imaging findings on admission, and it is important to make a diagnosis based on medical history and patient background.

Volumetric study reveals the relationship between outcome and early radiographic response during bevacizumab-containing chemoradiotherapy for unresectable glioblastoma.

PURPOSE: Although we have shown the clinical benefit of bevacizumab (BEV) in the treatment of unresectable newly diagnosed glioblastomas (nd-GBM), the relationship between early radiographic response and survival outcome remains unclear. We performed a volumetric study of early radiographic responses in nd-GBM treated with BEV. METHODS: Twenty-two patients with unresectable nd-GBM treated with BEV during concurrent temozolomide radiotherapy were analyzed. An experienced neuroradiologist interpreted early responses on fluid-attenuated inversion recovery (FLAIR) and gadolinium-enhanced T1-weighted images (GdT1WI). Volumetric changes were evaluated using diffusion-weighted imaging (DWI) and GdT1WI according to the Response Assessment in Neuro-Oncology (RANO) criteria. The results were categorized into improved (complete response [CR] or partial response [PR]) or non-improved (stable disease [SD] or progressive disease [PD]) groups; outcomes were compared using Kaplan-Meier analysis. RESULTS: The volumetric GdT1WI improvement was a significant predictive factor for overall survival (OS) prolongation (p = 0.0093, median OS: 24.7 vs. 13.6 months); however, FLAIR and DWI images were not predictive. The threshold for the neuroradiologist's interpretation of improvement in GdT1WI was nearly 20% of volume reduction, which was lesser than 50%, the definition of PR applied in the RANO criteria. However, even less stringent neuroradiologist interpretation could successfully predict OS prolongation (improved vs. non-improved: p = 0.0067, median OS: 17.6 vs. 8.3 months). Significant impact of OS on the early response in volumetric GdT1WI was observed within the cut-off range of 20-50% (20%, p = 0.0315; 30%, p = 0.087; 40%, p = 0.0456). CONCLUSIONS: Early response during BEV-containing chemoradiation can be a predictive indicator of patient outcome in unresectable nd-GBM.

Diagnostic accuracy for the epileptogenic zone detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT.

OBJECTIVES: To examine the utility of FDG-PET/MRI in patients with epilepsy by comparing the diagnostic accuracy of PET/MRI and PET/CT in epileptogenic zone (EZ) detection. METHODS: This prospective study included 31 patients (17 males, 14 females) who underwent surgical resection for EZ. All patients were first scanned using FDG-PET/CT followed immediately with FDG-PET/MRI. Two series of PET plus standalone MR images were interpreted independently by five board-certified radiologists. A 4-point visual score was used to assess image quality. Sensitivities and visual scores from both PETs and standalone MRI were compared using the McNemar test with Bonferroni correction and Dunn's multiple comparisons test. RESULTS: The EZs were confirmed histopathologically via resection as hippocampal sclerosis (n = 11, 35.5%), gliosis (n = 8, 25.8%), focal cortical dysplasia (n = 6, 19.4%), and brain tumours (n = 6, 19.4%) including cavernous haemangioma (n = 3), dysembryoplastic neuroepithelial tumour (n = 1), ganglioglioma (n = 1), and polymorphous low-grade neuroepithelial tumour of the young (n = 1). The sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). The visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT, as well as standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3). CONCLUSIONS: The diagnostic accuracy for the EZ detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT. KEY POINTS: • Sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). • Visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT and standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). • Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3).

First-line bevacizumab contributes to survival improvement in glioblastoma patients complementary to temozolomide.

INTRODUCTION: First-line bevacizumab (BEV) is now available as a treatment option for glioblastoma patients with severe clinical conditions in Japan. However, the survival benefits remain controversial. To elucidate these potential survival benefits, we retrospectively analyzed survival in glioblastoma patients receiving BEV. METHODS: We analyzed survival in 120 patients with IDH-wild type glioblastoma treated from 2002 to 2018. Overall survival (OS) was assessed in three treatment era subgroups [pre-temozolomide (TMZ), TMZ, and TMZ-BEV], and the correlations of prognostic factors with survival were evaluated. RESULTS: An improvement in survival was observed after BEV approval (median OS in the pre-TMZ, TMZ, and TMZ-BEV eras: 14.6, 14.9, and 22.1 months, respectively). A Cox proportional hazards model identified extent of resection and MGMT methylation status as significant prognostic factors in the TMZ era; however, these factors were not significant in the TMZ-BEV era. In subgroup analyses, patients with MGMT methylation had improved OS after TMZ introduction (pre-TMZ vs. TMZ, 18.5 vs. 28.1 months; P = 0.13), and those without MGMT methylation had significantly increased OS after BEV approval (TMZ vs. TMZ-BEV, 12.2 vs. 16.7 months; P = 0.04). CONCLUSIONS: Our findings imply that optional first-line administration of BEV can overcome the impact of conventional risk factors and prolong survival complementary to TMZ. The patient subgroups benefitting from TMZ and BEV did not seem to overlap, and stratification based on risk factors, including MGMT methylation status, might be effective for selecting patients in whom BEV should be preferentially used as a first-line therapy.

Vessel-selective 4D-MR angiography using super-selective pseudo-continuous arterial spin labeling may be a useful tool for assessing brain AVM hemodynamics.

OBJECTIVES: To evaluate the usefulness of 4D-MR angiography based on super-selective pseudo-continuous ASL combined with keyhole and view-sharing (4D-S-PACK) for vessel-selective visualization and to examine the ability of this technique to visualize brain arteriovenous malformations (AVMs). METHODS: In this retrospective study, 15 patients (ten men and five women, mean age 44.0 ± 16.9 years) with brain AVMs were enrolled. All patients were imaged with 4D-PACK (non-selective), 4D-S-PACK, and digital subtraction angiography (DSA). Observers evaluated vessel selectivity, identification of feeding arteries and venous drainage patterns, visualization scores, and contrast-to-noise ratio (CNR) for each AVM component. Measurements were compared between the MR methods. RESULTS: Vessel selectivity was graded 4 in 43/45 (95.6%, observer 1) and 42/45 (93.3%, observer 2) territories and graded 3 in two (observer 1) and three (observer 2) territories. The sensitivity and specificity for identification of feeding arteries for both observers was 88.9% and 100% on 4D-PACK, and 100% and 100% on 4D-S-PACK, respectively. For venous drainage, the sensitivity and specificity was 100% on both methods for observer 1. The sensitivity and specificity for observer 2 was 94.4% and 83.3% on 4D-PACK, and 94.4% and 91.7% on 4D-S-PACK, respectively. The CNRs at the timepoint of 1600 ms were slightly lower in 4D-S-PACK than in 4D-PACK for all AVM components (Feeding artery, p = .02; nidus, p = .001; and draining artery, p = .02). The visualization scores for both observers were not significantly different between 4D-PACK and 4D-S-PACK for all components. CONCLUSIONS: 4D-S-PACK could be a useful non-invasive clinical tool for assessing hemodynamics in brain AVMs. KEY POINTS: • The 4D-MR angiography based on super-selective pseudo-continuous arterial spin labeling combined with CENTRA-keyhole and view-sharing (4D-S-PACK) enabled excellent vessel selectivity. • The 4D-S-PACK enabled the perfect identification of feeding arteries of brain arteriovenous malformation (AVM). • 4D-S-PACK could be a non-invasive clinical tool for assessing hemodynamics in brain AVMs.

Differentiation of high-grade from low-grade diffuse gliomas using diffusion-weighted imaging: a comparative study of mono-, bi-, and stretched-exponential diffusion models.

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.

Robust visualization of middle cerebral artery main trunk by enhanced acceleration-selective arterial spin labeling (eAccASL) for intracranial MRA.

PURPOSE: A new sequence for intracranial MRA is developed, named enhanced acceleration-selective arterial spin labeling (eAccASL), to improve main artery visualization at middle cerebral artery (MCA). The aim of this study is to assess the visualization improvement using eAccASL, compared with the previously developed AccASL. METHODS: eAccASL and AccASL were performed in 8 healthy volunteers and images were compared between the 2 sequences. One patient with Moyamoya disease was evaluated by eAccASL and time of flight. For the volunteer images, vessel visualization was assessed by measuring the contrast-to-noise ratio between MCA M1 to M4 and white matter and by counting the peripheral arteries. Venous artifact level was assessed by measuring the contrast-to-noise ratio between the confluence of the sinuses and white matter and by evaluating cortical vein visualization. For the patient images, qualitative assessment of peripheral and collateral vessel visualization was conducted. RESULTS: In the MCA main trunk, higher arterial signal intensity, with reduced flow void, was observed in eAccASL compared with AccASL. Contrast-to-noise ratios of M1 to M3 for eAccASL were significantly higher than those of AccASL. There was no significant difference between AccASL and eAccASL for venous artifact. CONCLUSION: eAccASL could produce better MCA main trunk visualization compared with AccASL, while maintaining good venous signal suppression.