Brain

Differentiation between Treatment-Induced Necrosis and Recurrent Tumors in Patients with Metastatic Brain Tumors: Comparison among 11C-Methionine-PET, FDG-PET, MR Permeability Imaging, and MRI-ADC—Preliminary Results

Editor’s Choice

The authors evaluated the feasibility of MR permeability imaging by comparison with 11C-methionine-PET, FDG-PET, and DWI for differentiating radiation necrosis from recurrent tumors in 15 patients with 18 lesions following gamma knife radiosurgery. The area under the ROC curve for differentiating radiation necrosis from recurrent tumors was the best for the 11C-methionine ratio (0.90) followed by the contrast-enhancement ratio (0.81), maximum slope of increase (millimole/second) (0.80), and the initial area under the signal intensity–time curve (0.78). They conclude that PET using 11C-methionine may be superior to MR permeability imaging, ADC, and FDG-PET for differentiating radiation necrosis from recurrent tumors after gamma knife radiosurgery for metastatic brain tumors.

Prevalence of Traumatic Findings on Routine MRI in a Large Cohort of Professional Fighters

Fellows’ Journal Club

Conventional 3T MR imaging was used to assess 499 fighters (boxers, mixed martial artists, and martial artists) and 62 controls for nonspecific WM changes, cerebral microhemorrhage, cavum septum pellucidum, and cavum vergae. Fighters had an increased prevalence of cerebral microhemorrhage (4.2% versus 0% for controls), cavum septum pellucidum (53.1% versus 17.7% for controls), and cavum vergae (14.4% versus 0% for controls). This study assessed MR imaging findings in a large cohort demonstrating a significantly increased prevalence of cavum septum pellucidum among fighters. Although cerebral microhemorrhages were higher in fighters than in controls, this finding was not statistically significant.

Diffusional Kurtosis Imaging and Motor Outcome in Acute Ischemic Stroke

Editor’s Choice

The authors evaluated 17 patients with stroke who underwent brain diffusional kurtosis imaging within 4 days after the onset of symptoms. Neurologic evaluation included the Fugl-Meyer Upper Extremity Motor scale in the acute phase and 3 months poststroke. The largest percentage signal changes of the lesioned hemisphere corticospinal tract were observed with axial kurtosis, with an average 12% increase compared with the contralateral corticospinal tract. The strongest associations between the 3-month Fugl-Meyer Upper Extremity Motor scale score and diffusion metrics were found for the lesioned/contralateral hemisphere corticospinal tract mean kurtosis and axial kurtosis ratios. They conclude that diffusion metrics related to kurtosis were found to be more sensitive than conventional diffusivity metrics to early poststroke corticospinal tract microstructural changes.

The Use of Noncontrast Quantitative MRI to Detect Gadolinium-Enhancing Multiple Sclerosis Brain Lesions: A Systematic Review and Meta-Analysis

Editor’s Choice

The authors evaluated 37 journal articles that included 985 patients with MS who had MR imaging in which T1-weighted postcontrast sequences were compared with noncontrast sequences obtained during the same MR imaging examination by using ROI analysis of individual MS lesions. DTI-based fractional anisotropy values were significantly different between enhancing and nonenhancing lesions, with enhancing lesions showing decreased FA. None of the other most frequently studied MR imaging biomarkers (mean diffusivity, magnetization transfer ratio, or ADC) were significantly different between enhancing and nonenhancing lesions. They conclude that noncontrast MR imaging techniques, such as DTI-based FA, can assess MS lesion acuity without gadolinium.

Synthetic MRI for Clinical Neuroimaging: Results of the Magnetic Resonance Image Compilation (MAGiC) Prospective, Multicenter, Multireader Trial

Editor’s Choice

The authors performed a prospective multireader, multicase noninferiority trial of 1526 images read by 7 blinded neuroradiologists with prospectively acquired synthetic and conventional brain MR imaging case-control pairs from 109 subjects with neuroimaging indications. Each case included conventional T1- and T2-weighted, T1 and T2 FLAIR, and STIR and/or proton density and synthetic reconstructions from multiple-dynamic multiple-echo imaging. Images were randomized and independently assessed. Overall synthetic MR imaging quality was similar to that of conventional proton-density, STIR, and T1- and T2-weighted contrast views across neurologic conditions. Artifacts were more common in synthetic T2 FLAIR, but were readily recognizable and did not mimic pathology.

Differentiation of Enhancing Glioma and Primary Central Nervous System Lymphoma by Texture-Based Machine Learning

Fellows’ Journal Club

The authors evaluated the diagnostic performance of a machine-learning algorithm by using texture analysis of contrast-enhanced T1-weighted images for differentiation of primary central nervous system lymphoma (n=35) and enhancing glioma (n=71). The mean areas under the receiver operating characteristic curve were 0.877 for the support vector machine classifier; 0.878 for reader 1; 0.899 for reader 2; and 0.845 for reader 3. They conclude that support vector machine classification based on textural features of contrast-enhanced T1WI is noninferior to expert human evaluation in the differentiation of primary central nervous system lymphoma and enhancing glioma.

Heterogeneity of Cortical Lesion Susceptibility Mapping in Multiple Sclerosis

Editor’s Choice

The authors characterized the susceptibility mapping of cortical lesions in patients with MS (n=36) and compared it with neuropathologic observations (n=16). Neuropathologic analysis revealed the presence of an intense band of microglia activation close to the pial membrane in subpial cortical lesions or to the WM border of leukocortical cortical lesions. The quantitative susceptibility mapping analysis revealed 131 cortical lesions classified as hyperintense; 33, as isointense; and 84, as hypointense. They conclude that cortical lesion susceptibility maps are highly heterogeneous, even at individual levels and that the quantitative susceptibility mapping hyperintensity edge found in proximity to the pial surface might be due to the subpial gradient of microglial activation.

Clinical and Imaging Characteristics of Diffuse Intracranial Dolichoectasia

Fellows’ Journal Club

The authors retrospectively reviewed a consecutive series of patients with diffuse intracranial dolichoectasia and compared demographics, vascular risk factors, additional aneurysm prevalence, and clinical outcomes with a group of patients with vertebrobasilar dolichoectasia. Twenty-five patients had diffuse intracranial dolichoectasia, and 139 had vertebrobasilar dolichoectasia. Patients with diffuse intracranial dolichoectasia were older than those with vertebrobasilar dolichoectasia and had a higher prevalence of abdominal aortic aneurysms, other visceral aneurysms, and smoking history. Patients with diffuse intracranial dolichoectasia were more likely to have aneurysm growth. They conclude that the natural history of patients with diffuse intracranial dolichoectasia is significantly worse than that in those with isolated vertebrobasilar dolichoectasia.

Site and Rate of Occlusive Disease in Cervicocerebral Arteries: A CT Angiography Study of 2209 Patients with Acute Ischemic Stroke

Fellows’ Journal Club

The authors used CTA to assess arterial stenosis and occlusion in an ischemic stroke population arriving at a tertiary stroke center within 24 hours of symptom onset to obtain a comprehensive picture of occlusive disease pattern. Extra- and intracranial pathology, defined as stenosis of ≥50% and occlusions, were registered and classified into 21 prespecified segments. In the 50,807 arterial segments available for revision, 1851 (3.6%) abnormal segments were in the ischemic (symptomatic) territory and another 408 (0.8%) were outside it (asymptomatic). In the 1211 patients with ischemic stroke imaged within 6 hours of symptom onset, 40.7% had symptomatic large, proximal occlusions. They conclude that CTA in patients with acute ischemic stroke shows large individual variations of occlusion sites and degrees. Approximately half of patients have no visible occlusive disease, and 40% imaged within 6 hours show large, proximal segment occlusions amenable to endovascular therapy.

A Multiparametric Model for Mapping Cellularity in Glioblastoma Using Radiographically Localized Biopsies

Editor’s Choice

Ninety-one localized biopsies were obtained from 36 patients with glioblastoma. Signal intensities corresponding to these samples were derived from T1-postcontrast subtraction, T2-FLAIR, and ADC sequences by using an automated coregistration algorithm. Cell density was calculated for each specimen by using an automated cell-counting algorithm. T2-FLAIR and ADC sequences were inversely correlated with cell density. T1-postcontrast subtraction was directly correlated with cell density. The authors conclude that the model illustrates a quantitative and significant relationship between MR signal and cell density. Applying this relationship over the entire tumor volume allows mapping of the intratumoral heterogeneity for both enhancing core and nonenhancing margins.