Editor’s Choices

Dynamic Contrast-Enhanced MRI–Derived Intracellular Water Lifetime (τi): A Prognostic Marker for Patients with Head and Neck Squamous Cell Carcinomas

Editor’s Choice

The authors evaluated 60 patients with dynamic contrast-enhanced MR imaging before treatment. Median, mean intracellular water molecule lifetime, and volume transfer constant values from metastatic nodes were computed from each patient. Kaplan-Meier analyses were performed to associate mean intracellular water molecule lifetime and volume transfer constant and their combination with overall survival and beyond. Patients with high mean intracellular water molecule lifetime had overall survival significantly prolonged by 5 years compared with those with low mean intracellular water molecule lifetime. Patients with high mean intracellular water molecule lifetime had significantly longer overall survival at long-term duration than those with low mean intracellular water molecule lifetime. Volume transfer constant was a significant predictor for only the 5-year follow-up period. They conclude that a combined analysis of mean intracellular water molecule lifetime and volume transfer constant provided the best model to predict overall survival in patients with squamous cell carcinomas of the head and neck.

Reproducibility of Deep Gray Matter Atrophy Rate Measurement in a Large Multicenter Dataset

Editor’s Choice

The authors assessed the reproducibility of 2 automated segmentation software packages (FreeSurfer and the FMRIB Integrated Registration and Segmentation Tool) by quantifying the volume changes of deep GM structures by using back-to-back MR imaging scans from the Alzheimer Disease Neuroimaging Initiative’s multicenter dataset in 562 subjects. Back-to-back differences in 1-year percentage volume change were approximately 1.5–3.5 times larger than the mean measured 1-year volume change of those structures. They conclude that longitudinal deep GM atrophy measures should be interpreted with caution and that deep GM atrophy measurement techniques require substantially improved reproducibility, specifically when aiming for personalized medicine.

MR Elastography Analysis of Glioma Stiffness and IDH1-Mutation Status

Editor’s Choice

Tumor stiffness properties were prospectively quantified in 18 patients with histologically proved gliomas using MR elastography. Images were acquired on a 3T MR imaging unit with a vibration frequency of 60 Hz. Tumor stiffness was compared with unaffected contralateral white matter, across tumor grade, and by IDH1-mutation status. Gliomas were softer than healthy brain parenchyma, 2.2kPa compared with 3.3kPa, with grade IV tumors softer than grade II. MR elastography demonstrated that not only were gliomas softer than normal brain but the degree of softening was directly correlated with tumor grade and IDH1-mutation status.

Preoperative Cerebral Oxygen Extraction Fraction Imaging Generated from 7T MR Quantitative Susceptibility Mapping Predicts Development of Cerebral Hyperperfusion following Carotid Endarterectomy

Editor’s Choice

Seventy-seven patients with unilateral internal carotid artery stenosis underwent preoperative 3DT2*-weighted imaging using a multiple dipole-inversion algorithm with a 7T MR scanner. Quantitative susceptibility mapping images wereobtained, and oxygen extraction fraction maps were generated. Quantitative brain perfusion single-photon emission CT was alsoperformed before and immediately after carotid endarterectomy. Ten patients (13%) showed post–carotid endarterectomy hyperperfusion. Multivariate analysis showed that a high quantitative susceptibility mapping–oxygen extraction fraction ratio was significantly associated with the development of post–carotid endarterectomy hyperperfusion.

Predictors of Incomplete Occlusion following Pipeline Embolization of Intracranial Aneurysms: Is It Less Effective in Older Patients?

Editor’s Choice

This was a retrospective analysis of 465 consecutive aneurysms treated with the Pipeline Embolization Device between 2009 and 2016, at 3 academic institutions in the United States. Cases with angiographic follow-up were selected to evaluate factors predictive of incomplete aneurysm occlusion at last follow-up. Older age (more than 70 years), nonsmoking status, aneurysm location within the posterior communicating artery or posterior circulation, greater aneurysm maximal diameter (>21 mm), and shorter follow-up time (<12 months) were significantly associated with incomplete aneurysm occlusion at last angiographic follow-up.

Photon-Counting CT of the Brain: In Vivo Human Results and Image-Quality Assessment

Editor’s Choice

Radiation dose–matched energy-integrating detector and photon-counting detector head CT scans were acquired with standardized protocols (tube voltage/current, 120 kV(peak)/370 mAs) in both an anthropomorphic head phantom and 21 asymptomatic volunteers. Image noise, gray matter, and white matter signal-to-noise ratios and GM–WM contrast and contrast-to-noise ratios were measured. Image quality was scored by 2 neuroradiologists blinded to the CT detector type. Photon-counting detector brain CT scans demonstrated greater gray–white matter contrast compared with conventional CT. This was due to both higher soft-tissue contrast and lower image noise for photon-counting CT.

Real-Time Motor Cortex Mapping for the Safe Resection of Glioma: An Intraoperative Resting-State fMRI Study

Editor’s Choice

The authors conducted preoperative and intraoperative resting-state intrinsic functional connectivity analyses of the motor cortex in 30 patients with brain tumors. Factors that may influence intraoperative imaging quality, including anesthesia type and tumor cavity, were studied. Additionally, direct cortical stimulation was used to validate the accuracy of intraoperative resting-state fMRI in mapping the motor cortex. Fourteen patients who successfully completed both sufficient intraoperative resting-state fMRI and direct cortical stimulation were used for further analysis of sensitivity and specificity. Compared with those subjected to direct cortical stimulation, the sensitivity and specificity of intraoperative resting-state fMRI in localizing the motor area were 61.7% and 93.7%, respectively. They conclude that using intraoperative resting-state fMRI can avoid the risk of intraoperative seizures due to direct cortical stimulation and may provide neurosurgeons with valuable information to facilitate the safe resection of gliomas.

Angioarchitectures and Hemodynamic Characteristics of Posterior Communicating Artery Aneurysms and Their Association with Rupture Status

Editor’s Choice

The authors studied 313 posterior communicating artery aneurysms (145 ruptured, 168 unruptured) with image-based computational fluid dynamics. Aneurysms were classified into different angioarchitecture types depending on the location of the aneurysm with respect to parent artery bifurcation. Ruptured aneurysms had higher, more concentrated, and more oscillatory wall shear stress distributions; stronger and more concentrated inflow jets; and more complex and unstable flow patterns compared with unruptured aneurysms. They conclude that high-flow intrasaccular hemodynamic characteristics, commonly found in bifurcation-type angioarchitectures, are associated with the posterior communicating artery aneurysm rupture status.

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.

Multicenter Experience with FRED Jr Flow Re-Direction Endoluminal Device for Intracranial Aneurysms in Small Arteries

Editor’s Choice

The authors assessed the clinical safety and efficacy of the Flow Re-Direction Endoluminal Device Jr (FRED Jr) dedicated to small-vessel diameters between 2.0 and 3.0 mm in 42 patients with 47 aneurysms. The primary efficacy end point of complete or near complete occlusion was reached at 1 month in 27/41 (66%), at 6 months in 21/27 (78%), and at 12 months in 11/11 (100%) aneurysms.