BACKGROUND AND PURPOSE: Intravoxel incoherent motion imaging, which simultaneously measures diffusion and perfusion parameters, is promising for brain tumor grading. However, intravoxel incoherent motion imaging has not been tested in children. The purpose of this study was to evaluate the correlation between intravoxel incoherent motion parameters and histology to assess the accuracy of intravoxel incoherent motion imaging for pediatric intracranial tumor grading.

Purpose To evaluate and compare the performance of acceleration-selective arterial spin labeling (AccASL) magnetic resonance (MR) angiography in the visualization of cerebral arteries and collateral vessels in patients with Moyamoya disease with that of time-of-flight (TOF) MR angiography, with digital subtraction angiography (DSA) as the reference standard. Materials and Methods Thirty-six cerebral hemispheres from 22 patients with Moyamoya disease underwent TOF and AccASL MR angiography and DSA. Qualitative evaluations included imaging of the terminal internal carotid artery (ICA), distal middle cerebral arteries (MCAs), Moyamoya vessels, and leptomeningeal anastomosis (LMA) collaterals with reference to DSA. Quantitative evaluations included assessment of contrast-to-noise ratio (CNR) and number of vessels in MCA branches. The linear mixed-effect model was used to compare the two methods. Results Mean scores for qualitative evaluation were significantly higher with AccASL angiography than with TOF angiography for imaging distal MCAs (3.9 ± 0.3 [standard deviation] vs 2.9 ± 1.1; P < .001), Moyamoya vessels (3.6 ± 0.6 vs 2.7 ± 0.9, P < .001), and LMA collaterals (3.8 ± 0.6 vs 1.8 ± 0.7, P < .001). Scores for steno-occlusive degree around the terminal ICAs were better with TOF angiography than with AccASL angiography (2.6 ± 0.5 vs 2.4 ± 0.6, P = .023). CNRs in the M4 segment were significantly higher with AccASL angiography (11.9 ± 12.9, P < .001) than with TOF angiography (4.1 ± 7.9). The number of vessels was significantly higher with AccASL angiography (18.3 ± 5.0, P < .001) than with TOF angiography (8.9 ± 4.9). The increase in the number of vessels from TOF angiography to AccASL angiography was greater in patients with severe ICA steno-occlusion (late ICA stage group, 11.4 ± 4.5; early ICA stage group, 6.8 ± 4.0; P = .007) and well-developed leptomeningeal anastomosis (mildly developed LMA group, 7.1 ± 4.3; well-developed LMA group, 11.3 ± 4.5; P = .011). Conclusion AccASL MR angiography enables better visualization of distal cerebral arteries and collateral vessels in patients with Moyamoya disease than does TOF MR angiography, while TOF MR angiography enables better visualization of stenosis of proximal arteries. Both methods work in a mutually beneficial manner in the assessment of cerebral arteries. RSNA, 2017 Online supplemental material is available for this article.

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).

• ADC of lymphoma was significantly lower than that of inflammation. • ADC derived from TSE DWI showed the best diagnostic performance. • This study was conducted by a 3-T MR scanner.