Brain

Arterial Spin-Labeling Perfusion MR Imaging Demonstrates Regional CBF Decrease in Idiopathic Normal Pressure Hydrocephalus

Fellows’ Journal Club

The authors assessed regional CBF in patients with idiopathic normal pressure hydrocephalus compared with healthy controls using the noninvasive quantitative arterial spin-labeling MR imaging technique. Twenty-one consecutive patients with NPH and 21 age- and sex-matched randomly selected healthy controls from a population registry were prospectively included. In patients with idiopathic NPH, perfusion was reduced in the periventricular white matter,lentiform nucleus, and thalamus compared with controls. They conclude that using pseudocontinuous ASL, they confirmed the findings of reduced perfusion in the periventricular white matter, basal ganglia, and thalamus in patients with idiopathic NPH previously observed with other imaging techniques.

The Brain Thermal Response as a Potential Neuroimaging Biomarker of Cerebrovascular Impairment

Editor’s Choice

The authors evaluated the use of noninvasive MR thermometry in patients with cerebrovascular disease, and hypothesized that the presence of a measurable brain thermalresponse would reflect the tissue hemodynamic state. MR imaging and MR thermometry were performed in 10 patients undergoing acetazolamide challenge for chronic, anterior circulation steno-occlusive disease. Cerebrovascular reactivity was calculated with BOLD imaging and arterial spin-labeling methods. Brain temperature was calculated pre- and post-acetazolamide using previously established chemical shift thermometry. They observed significant, voxelwise quadratic relationships between cerebrovascular reactivity from BOLD imaging and the brain thermal response and baseline brain temperatures, concluding that brain thermal response is a potential noninvasive biomarker for cerebrovascular impairment.

Improved Detection of Anterior Circulation Occlusions: The “Delayed Vessel Sign” on Multiphase CT Angiography

Fellows’ Journal Club

The authors evaluated 23 distal anterior circulation occlusions during a 2-year period. Ten M1-segment occlusions and 10 cases without a vessel occlusion were also included. There was significant improvement in the sensitivity of detection of distal anterior circulation vessel occlusions, overall confidence, and time taken to interpret with multiphase CTA compared with single-phase CTA. The delayed vessel sign is a reliable indicator of anterior circulation vessel occlusion, particularly in cases involving distal branches.

Multinodular and Vacuolating Neuronal Tumor of the Cerebrum: A New “Leave Me Alone” Lesion with a Characteristic Imaging Pattern

Fellows’ Journal Club

The most recent 2016 WHO classification includes MVNT as a unique cytoarchitectural pattern of gangliocytoma, though it remains unclear whether MVNT is a true neoplastic process or a dysplastic hamartomatous/malformative lesion. The authors report 33 cases of presumed multinodular and vacuolating neuronal tumor of the cerebrum that exhibit a remarkably similar pattern of imaging findings consisting of a subcortical cluster of nodular lesions. They conclude that these are benign, nonaggressive lesions that do not require biopsy in asymptomatic patients and behave more like a malformative process than a true neoplasm.

Concordance of Time-of-Flight MRA and Digital Subtraction Angiography in Adult Primary Central Nervous System Vasculitis

Editor’s Choice

The authors compared the diagnostic concordance of vessel imaging using 3D-TOF-MRA and DSA in 85 patients with primary central nervous system vasculitis. Among the 25 patients with abnormal DSA findings, 24 demonstrated abnormal 3D-TOF-MRA findings, whereas all 6 remaining patients with normal DSA findings had normal 3D-TOF-MRA findings. They conclude that 3D-TOF-MRA shows a high concordance with DSA in diagnostic performance when analyzing vasculature in patients with primary central nervous system vasculitis and that with negative 3T 3D-TOF-MRA findings, the added diagnostic value of DSA is limited.

3D Pseudocontinuous Arterial Spin-Labeling MR Imaging in the Preoperative Evaluation of Gliomas

Editor’s Choice

Fifty-eight patients with pathologically confirmed gliomas underwent preoperative 3D pseudocontinuous arterial spin-labeling and ROC curves were generated for parameters to distinguish high-grade from low-grade gliomas. Both maximum CBF and maximum relative CBF were significantly higher in high-grade than in low-grade gliomas. After adjustment for age, a higher maximum CBF and higher maximum relative CBF were associated with worse progression-free survival.

Hippocampal and Deep Gray Matter Nuclei Atrophy Is Relevant for Explaining Cognitive Impairment in MS: A Multicenter Study

Editor’s Choice

Brain dual-echo, 3D T1-weighted, and double inversion recovery scans were acquired at 3T from 62 patients with relapsing-remitting MS and 65 controls. Focal WM and cortical lesions were identified, and volumetric measures from WM, cortical GM, the hippocampus, and deep GM nuclei were obtained. Compared with those with who were cognitively preserved, patients with MS with cognitive impairment had higher T2 and T1 lesion volumes and a trend toward a higher number of cortical lesions. Significant brain, cortical GM, hippocampal, deep GM nuclei, and WM atrophy was found in patients with MS with cognitive impairment versus those who were cognitively preserved. The authors conclude that hippocampal and deep GM nuclei atrophy are key factors associated with cognitive impairment in MS.

Identification and Quantitative Assessment of Different Components of Intracranial Atherosclerotic Plaque by Ex Vivo 3T High-Resolution Multicontrast MRI

Editor’s Choice

Fifty-three intracranial arterial specimens with atherosclerotic plaques from 20 cadavers were imaged by 3T MR with T1, T2, and proton-density–weighted FSE and STIR sequences. The signal characteristics and areas of fibrous cap, lipid core, calcification, fibrous tissue, and healthy vessel wall were recorded on MR images and compared with histology. The signal intensity of the lipid core was significantly lower than that of the fibrous cap on T2-weighted, proton-density, and STIR sequences and was comparable on T1-weighted sequences. Optimal contrast between the lipid core and fibrous cap was found on T2-weighted images. Ex vivo 3T MR imaging can accurately identify and quantitatively assess intracranial atherosclerotic plaque components, providing a direct reference for in vivo intracranial plaque imaging.

Amide Proton Transfer Imaging Allows Detection of Glioma Grades and Tumor Proliferation: Comparison with Ki-67 Expression and Proton MR Spectroscopy Imaging

Editor’s Choice

Amide proton transfer–weighted imaging (APTWI) is a novel molecular MR imaging technique developed to detect and quantitatively visualize endogenous proteins and peptides. APTWI is usually reported in terms of asymmetry in the magnetization transfer ratio at 3.5 ppm. This study included 42 patients with low-grade (n = 28) or high-grade (n = 14) glioma, all of whom underwent conventional MR imaging, proton MR spectroscopy imaging, and amide proton transfer–weighted imaging on the same 3T scanner within 2 weeks before surgery. The asymmetric magnetization transfer ratio at 3.5 ppm values measured by different readers showed good concordance and were significantly higher in high-grade gliomas than in low-grade gliomas, with sensitivity and specificity values of 92.9% and 71.4%, respectively, at a cutoff value of 2.93%. The asymmetric magnetization transfer ratio at 3.5 ppm may serve as a potential biomarker not only for assessing proliferation, but also for predicting histopathologic grades in gliomas.

Diagnostic Performance of a 10-Minute Gadolinium-Enhanced Brain MRI Protocol Compared with the Standard Clinical Protocol for Detection of Intracranial Enhancing Lesions

Fellows’ Journal Club

A total of 53 patients underwent MR imaging consisting of 5 basic fast precontrast sequences plus standard and accelerated versions of the same postcontrast T1WI sequences. Two neuroradiologists assessed the image quality and the final diagnosis for each set of postcontrast sequences and compared their performances. The 10-minute brain MR imaging protocol with contrast was comparable in diagnostic performance with the standard protocol in an inpatient motion-prone population, with the additional benefits of reducing acquisition times and image artifacts.