Author: jross

Jeffrey Ross • Mayo Clinic, Phoenix

Dr. Jeffrey S. Ross is a Professor of Radiology at the Mayo Clinic College of Medicine, and practices neuroradiology at the Mayo Clinic in Phoenix, Arizona. His publications include over 100 peer-reviewed articles, nearly 60 non-refereed articles, 33 book chapters, and 10 books. He was an AJNR Senior Editor from 2006-2015, is a member of the editorial board for 3 other journals, and a manuscript reviewer for 10 journals. He became Editor-in-Chief of the AJNR in July 2015. He received the Gold Medal Award from the ASSR in 2013.

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.

Journal Scan – This Month in Other Journals, May 2017

Wilson JR, Tetreault LA, Kim J, et al. State of the Art in Degenerative Cervical Myelopathy: An Update on Current Clinical Evidence. Neurosurgery. 2017;80(3S):S33-S45. doi:10.1093/neuros/nyw083.

Degenerative cervical myelopathy (DCM) is used to describe myelopathy resulting from degenerative pathology in the cervical spine including spondylosis, degenerative disc disease, ossification of the posterior longitudinal ligament (OPLL), and ossification of the ligamentum flavum. The authors provide a wide-ranging overview of the state of the art in degenerative cervical myelopathy, with a focus on updating the spine surgeon on the current evidence surrounding pathophysiology, natural history, imaging, outcome measures, and outcome prediction tools. They also provide an overview of the evidence for surgical vs. nonoperative management, and a summary of the literature regarding the most commonly used approaches to the cervical spine.

The pathophysiology of DCM includes both static and dynamic factors. Static factors result from congenital stenosis or acquired stenosis secondary to spondylosis and disc degeneration.Dynamic factors relate to exacerbation of spinal cord compression seen with physiological and, in the setting of degenerative subluxation, pathological motion of the cervical spine. In addition to physical compression, there is a reduction in blood supply leading to ischemia within the cord.  Pathological features of DCM include gray and white matter degeneration, anterior horn cell loss, cystic cavitation, and Wallerian degeneration of the posterior columns adjacent to the site of compression.

There is also likely a secondary cascade of neuroinflammation consisting of microglia activation and macrophage recruitment which occurs at the site of mechanical compression within the spinal cord. In the noncompressed nonmyelopathic spinal cord, the blood-spinal cord-barrier is isolated from the peripheral immune system; however, chronic compression renders the cord susceptible to cell infiltration that may be involved in

Imaging Characteristics of Pediatric Diffuse Midline Gliomas with Histone H3 K27M Mutation

Fellows’ Journal Club

The 2016 WHO Classification of Tumors of the Central Nervous System includes “diffuse midline glioma with histone H3 K27M mutation” as a new diagnostic entity. This study of 33 patients with diffuse midline gliomas found histone H3 K27M mutation was present in 24 patients (72.7%) and absent in 9 (27.3%). The location was the thalamus in 27.3%; the pons in 42.4%; within the vermis/fourth ventricle in 15%; and the spinal cord in 6%. The radiographic features of diffuse midline gliomas with histone H3 K27M mutation were highly variable, ranging from expansile masses without enhancement or necrosis with large areas of surrounding infiltrative growth to peripherally enhancing masses with central necrosis with significant mass effect.

Feasibility of Flat Panel Detector CT in Perfusion Assessment of Brain Arteriovenous Malformations: Initial Clinical Experience

Editor’s Choice

Five patients with brain arteriovenous malformations were studied with flat panel detector CT, DSC-MR imaging, and vessel-encoded pseudocontinuous arterial spin-labeling. Flat panel detector CT, which was originally thought to measure blood volume, correlated more closely with ASL-CBF and DSC-CBF than with DSC-CBV. Flat panel detector CT perfusion depends on the time point chosen for data collection, which is triggered early in patients with AVMs. This finding, in combination with high data variability, makes flat panel detector CT inappropriate for perfusion assessment in brain AVMs.

Evaluation of Collaterals and Clot Burden Using Time-Resolved C-Arm Conebeam CT Angiography in the Angiography Suite: A Feasibility Study

Fellows’ Journal Club

Ten C-arm conebeam CT perfusion datasets from 10 subjects with acute ischemic stroke acquired before endovascular treatment were retrospectively processed to generate time-resolved conebeam CTA. From time-resolved conebeam CTA, 2 experienced readers evaluated the clot burden and collateral flow in consensus by using previously reported scoring systems and assessed the clinical value of this novel imaging technique. The 2 readers agreed that time-revolved C-arm conebeam CTA was the preferred method for evaluating the clot burden and collateral flow compared with other conventional imaging methods. They conclude that comprehensive evaluations of clot burden and collateral flow are feasible by using time-resolved C-arm conebeam CTA data acquired in the angiography suite.

MR Imaging of Individual Perfusion Reorganization Using Superselective Pseudocontinuous Arterial Spin-Labeling in Patients with Complex Extracranial Steno-Occlusive Disease

Editor’s Choice

Super selective pseudocontinuous arterial spin-labeling with a circular labeling spot enabling selective vessel labeling was added to routine imaging in a prospective pilot study in 50 patients with extracranial steno-occlusive disease. The detected vessel occlusions/stenoses and perfusion patterns corresponded between cerebral DSA and super selective pseudocontinuous ASL maps in all cases. Perfusion deficits on DSC-CBF maps significantly correlated with those on super selective pseudocontinuous ASL maps. The authors conclude that super selective pseudocontinuous ASL is a robust technique for regional brain perfusion imaging, suitable for the noninvasive diagnostics of individual patient perfusion patterns.

Genetically Defined Oligodendroglioma Is Characterized by Indistinct Tumor Borders at MRI

Fellows’ Journal Club

The authors wanted to determine whether imaging characteristics previously associated with oligodendroglial tumors were still applicable given the 2016 WHO classification that made IDH mutation and 1p/19q codeletion the defining features of oligodendroglioma. They found that 92% of genetically defined oligodendrogliomas had noncircumscribed borders, compared with 45% of non-1p/19q codeleted tumors with at least partial histologic oligodendroglial morphology. Ninety-nine percent of oligodendrogliomas were heterogeneous on T1- and/or T2-weighted imaging.

Combining Diffusion Tensor Metrics and DSC Perfusion Imaging: Can It Improve the Diagnostic Accuracy in Differentiating Tumefactive Demyelination from High-Grade Glioma?

Editor’s Choice

Fourteen patients with tumefactive demyelinating lesions and 21 patients with high-grade gliomas underwent MR imaging with conventional, DTI, and DSC perfusion imaging. Conventional imaging sequences had a sensitivity of 80.9% and specificity of 57.1% in differentiating high-grade gliomas from tumefactive demyelinating lesions. DTI metrics (p:q tensor decomposition) and DSC perfusion demonstrated a statistically significant difference among enhancing portions in tumefactive demyelinating lesions and high-grade gliomas. The highest specificity was found for ADC, the anisotropic component of the diffusion tensor, and relative CBV. The authors conclude that DTI and DSC perfusion add profoundly to conventional imaging in differentiating tumefactive demyelinating lesions and high-grade gliomas.

Journal Scan – This Month in Other Journals, April 2017

Zurawski J, Lassmann H, Bakshi R. Use of Magnetic Resonance Imaging to Visualize Leptomeningeal Inflammation in Patients With Multiple Sclerosis. JAMA Neurol. 2017;74(1):100. doi:10.1001/jamaneurol.2016.4237.

You are well aware that MS is a chronic demyelinating disease traditionally characterized by an initial relapsing-remitting clinical course and focal inflammatory lesions that have a predilection for the periventricular white matter.  However, histopathologic and imaging studies have illustrated a more complex pathologic substrate involving cortical demyelination, gray matter atrophy, and meningeal inflammation.  The authors evaluate the status and prospects regarding the emerging role of MR to visualize leptomeningeal enhancement (LME) in patients with MS and place these findings in the proper pathobiologic and clinical context.

Absinta et al (Absinta M, Vuolo L, Rao A, et al. Gadolinium-based MRI characterization of leptomeningeal inflammation in multiple sclerosis. Neurology. 2015;85(1):18-28.) found that LME was significantly more common than had been initially reported, and its presence was associated with patient age, disease severity, and clinical type of MS. The authors used high-resolution 3T 3-dimensional T2 FLAIR MRI with a voxel size of 1.0 × 1.0 × 1.0mm and postcontrast images obtained 10 minutes after gadolinium injection. They demonstrated LME in 74 of 299 patients with MS (24.7%) compared with only 1 of 37 (2.7%) age-matched controls with out MS. Perhaps of particular importance, LME was twice as frequent (33%) in patients with progressive forms of MS (present in 44 patients with secondary progressive MS) (SPMS) and 74 patients with primary progressive MS (PPMS) compared with those with relapsing-remitting (RR) disease (19%). Disease duration, and Expanded Disability Status Scale scores were associated with LME. Whole-brain and cortical atrophy were also associated with LME. There was no association between LME and WM lesion enhancement or WM lesion volume. Leptomeningeal enhancement topography abutted the pial surface on the cerebral convexity (19% …