Author: jross

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.

Baseline Survey of the Neuroradiology Work Environment in the United States with Reported Trends in Clinical Work, Nonclinical Work, Perceptions of Trainees, and Burnout Metrics

Fellows’ Journal Club

A voluntary survey was sent to practicing and out-of-training members of the ASNR. Four hundred thirty-two respondents across a broad range of experience reported: 93% with workdays extending at least 1 hour past expected; 71.9% reading more cases per hour compared with previous years; 79.5% sometimes-to-always interpreting cases faster than comfortable for optimal interpretation; and 67.8% sometimes or more often with inadequate time to discuss abnormal results. Burnout symptoms ranged between 49% and 75%. The trends and the correlations should be concerning to the leaders of radiology and warrant further monitoring.

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.

Journal Scan – This Month in Other Journals, July 2017

Rabinstein AA. Treatment of Acute Ischemic Stroke. Continuum (Minneap Minn). 2017;23(1, Cerebrovascular Disease):62-81. doi:10.1212/CON.0000000000000420.

This is an excellent and comprehensive review of current acute stroke treatment.  The three main principles of acute stroke care are: (1) achieve timely recanalization of the occluded artery and reperfusion of the ischemic tissue, (2) optimize collateral flow, and (3) avoid secondary brain injury. The author states there is incontrovertible evidence that IV thrombolysis with rtPA and endovascular thrombectomy with a retrievable stent improve neurologic outcomes in patients with acute ischemic stroke. Both treatments should be administered as quickly as possible after stroke onset, can be combined, and are safe in appropriately selected candidates. IV thrombolysis with rtPA is proven to be effective in improving functional outcomes after an ischemic stroke up to 4.5 hours after symptom onset. IV rtPA infused within 3 hours of symptom onset increases the chances of functional independence at 3 months by one-third. The benefit is time dependent and much stronger when the drug is administered within the first 90 minutes after symptom onset.

Regarding mechanical thrombectomy, the six positive trials shared the requirement of CT angiograms for patient screening (only patients with documented internal carotid artery or proximal middle cerebral artery occlusions could be entered into the studies), emphasized the importance of prompt intervention, and almost exclusively used retrievable stents to achieve reperfusion. All of the trials enrolled patients with severe neurologic deficits and good prestroke functional status who presented mostly within 6 hours of symptom onset. Major early ischemic changes on the baseline CT scan were a reason for exclusion. Patients treated with mechanical thrombectomy had high rates of reperfusion and much better functional outcomes at 90 days. Mechanical thrombectomy was also proven to be quite safe, with a pooled rate of

Clinically Feasible Microstructural MRI to Quantify Cervical Spinal Cord Tissue Injury Using DTI, MT, and T2*-Weighted Imaging: Assessment of Normative Data and Reliability

Fellows’ Journal Club

Forty healthy subjects underwent T2WI, DTI, magnetization transfer, and T2*WI at 3T in <35 minutes using standard hardware and pulse sequences. Cross-sectional area, fractional anisotropy, magnetization transfer ratio, and T2*WI WM/GM signal intensity ratio were calculated. Reliable multiparametric assessment of spinal cord microstructure is possible by using clinically suitable methods. These results establish normalization procedures and pave the way for clinical studies.

Resting-State Seed-Based Analysis: An Alternative to Task-Based Language fMRI and Its Laterality Index

Editor’s Choice

Eighteen healthy right-handed volunteers were prospectively evaluated with resting-state fMRI and task-based fMRI to assess language networks. The laterality indices of Broca and Wernicke areas were calculated by using task-based fMRI via a voxel-value approach. The authors performed seed-based resting-state fMRI connectivity analysis together with parameters such as amplitude of low-frequency fluctuation and fractional amplitude of low-frequency fluctuation (fALFF). fALFF can be used as an alternative to task-based fMRI for assessing language laterality. There was a strong positive correlation between the fALFF of the Broca area of resting-state fMRI with the laterality index of task-based fMRI.

Large Basilar Apex Aneurysms Treated with Flow-Diverter Stents

Fellows’ Journal Club

The authors report their experience treating basilar apex aneurysms with flow-diverter stents and evaluate their efficacy and safety profile in this specific condition. Of the 175 aneurysms treated with flow-diverter stents at their institution, 5 patients received flow-diverter stents for basilar apex aneurysms. The mean follow-up after stent deployment was 21 months. They conclude that flow diversion is a feasible technique with an efficacy demonstrated at a midterm follow-up, especially in the case of basilar apex aneurysm recurrences after previous endovascular treatments.

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.

Journal Scan – This Month in Other Journals, June 2017

Elshafeey N, Hassan I, Zinn PO, Colen RR. From K-space to Nucleotide. Top Magn Reson Imaging. 2017;26(1):1. doi:10.1097/RMR.0000000000000114.

Radiogenomics is a relatively new field within radiology that links different imaging features with diverse genomic events. Genomics advances provided by the Cancer Genome Atlas and the Human Genome Project have enabled researchers to harness and integrate this information with noninvasive imaging phenotypes to create a better 3-dimensional understanding of tumor behavior and biology.  This review summarizes the radiogenomic literature regarding brain tumors, both glioblastoma and lower grades.

As you know, the typical gross appearance of glioblastoma on MR is characterized as an irregular, ring-enhancing tumor with a central necrotic core and surrounding area of FLAIR hyperintensity. Each of these 3 imaging components (aka. phenotypes) of the tumor reflect a distinct tumor biology such as neovascularization and active tumor [contrast-enhancing component], edema/invasion (peritumoral T2/FLAIR hyperintensity), or cell death (necrosis). As an example of the potential power of volumetric features of glioblastoma on prognosis, in a cohort of 78 patients glioblastoma tumor volumes were quantified and combined with patient age and Karnofsky performance score (KPS) to create an easy-to-use 3-step scoring system VAK (Volume-Age, KPS) that can predict patient outcome.

Additionally, specific genomic and epigenetic events have shown a predilection for specific locations within the brain. As background, MGMT, a gene that encodes for a DNA repair enzyme, is associated with a better survival in those patients with MGMT promoter methylation receiving alkylating agents such as temozolomide.  In treatment-naive glioblastoma patients, it has been found that patients with unmethylated O-6- methylguanine-DNA methyltransferase (MGMT) promoter predominated in the right temporal lobe. Glioblastoma with MGMT promoter methylation, EGFR amplification, and EGFRvIII mutations tended to occur in in the left temporal lobe.  Most IDH1-mutated and intact PTEN tumors were in the frontal lobe.

3 tables,