Morris, Pearse

Arterial spin labeling (ASL) is a powerful noncontrast magnetic resonance imaging (MRI) technique that enables quantitative evaluation of brain perfusion. To optimize the clinical and research utilization of ASL, radiologists and physicists must understand the technical considerations and age‐related variations in normal and disease states. We discuss advanced applications of ASL across the lifespan, with example cases from children and adults covering a wide variety of pathologies. Through literature review and illustrated clinical cases, we highlight the subtleties as well as pitfalls of ASL interpretation. First, we review basic physical principles, techniques, and artifacts. This is followed by a discussion of normal perfusion variants based on age and physiology. The three major categories of perfusion abnormalities—hypoperfusion, hyperperfusion, and mixed patterns—are covered with an emphasis on clinical interpretation and relationship to the disease process. Major etiologies of hypoperfusion include large artery, small artery, and venous disease; other vascular conditions; global hypoxic–ischemic injury; and neurodegeneration. Hyperperfusion is characteristic of vascular malformations and tumors. Mixed perfusion patterns can be seen with epilepsy, migraine, trauma, infection/inflammation, and toxic‐metabolic encephalopathy.Level of Evidence4Technical Efficacy Stage3

Background Cerebral venous sinus stenting is an established treatment for patients with idiopathic intracranial hypertension (IIH), refractory to medical management and with stenotic venous sinus on conventional cerebral venography. Currently, there are no clear guidelines on optimal noninvasive imaging modality for routine post-stenting follow-up. We investigated diagnostic yield of CT venography (CTV) for evaluation of stent patency. Methods We reviewed our clinical database of patients with a diagnosis of IIH, who underwent stenting of stenotic transverse or transverse/sigmoid sinus junction. Patients who had follow-up CTVs after more than 30 days were included in the final study group. All CTVs were reviewed by two readers for in-stent thrombosis, extrinsic stent compression, juxta-stent stenosis, and new contralateral venous sinus stenosis. Inter-observer agreement and association of stent patency with clinical outcomes (headache and papilledema) were assessed. Results In all 36 included patients with 38 cerebral venograms for stenting, follow-up CTVs demonstrated adequate opacifications of the venous sinuses and stents for confident evaluation for in-stent thrombosis, extrinsic stent compression, juxta-stent stenosis, and new contralateral venous sinus stenosis, with inter-observer agreement coefficient of 0.7, 1.0, 0.8, and 1.0 respectively. Association between abnormal CTV and higher rates of persistent headache and lower rates of headache improvement/resolution was statistically significant (P-value of 0.01). Conclusion CTV is a reliable noninvasive imaging modality for evaluation of cerebral venous sinuses and stent patency following treatment of idiopathic intracranial hypertension with venous sinus stenting and could be used as a routine follow-up study.

Aim To describe the impact of steps towards reduction of procedural doses of radiation during neuroendovascular procedures. Methods Phantom exposures under controlled circumstances were performed using a Rando-Alderson adult-sized head phantom. Customized imaging protocols were devised for pediatric and adult imaging and implemented in clinical use. Outcome data for estimated skin doses (ESD) and dose–area product (DAP) following pediatric and adult diagnostic and interventional procedures over 4.5 years were analyzed retrospectively. Results Dose estimates were reduced by 50% or more after introduction of customized imaging protocols in association with modification of personnel behavior compared with doses recorded with previously used vendor-recommended protocols. Discussion Substantial reductions in radiation use during neuroendovascular procedures can be achieved through a combination of equipment modification and operator behavior.

Objective A novel autoimmune central nervous system (CNS) disorder with glial fibrillary acidic protein (GFAP)‐IgG as biomarker was recently characterized. Here, 102 patients with GFAP‐IgG positivity are described. Methods The 102 included patients had: (1) serum, cerebrospinal fluid (CSF), or both that yielded a characteristic astrocytic pattern of mouse tissue immunostaining; (2) confirmation of IgG reactive with specific GFAP isoforms (α, ɛ, or κ) by cell‐based assays; and (3) clinical data available. Control specimens (n = 865) were evaluated by tissue (n = 542) and cell‐based (n = 323) assays. Results Median symptom onset age was 44 years (range = 8–103), and 54% were women. The predominant phenotype (83 patients; 81%) was inflammation of meninges, brain, spinal cord, or all 3 (meningoencephalomyelitis). Among patients, highest specificity for those phenotypes was observed for CSF testing (94%), and highest sensitivity was for the GFAPα isoform (100%). Rare GFAP‐IgG positivity was encountered in serum controls by tissue‐based assay (0.5%) or cell‐based assay (1.5%), and in CSF controls by cell‐based assay (0.9%). Among patients, striking perivascular radial enhancement was found on brain magnetic resonance imaging in 53%. Although cases frequently mimicked vasculitis, angiography was uniformly negative, and spinal imaging frequently demonstrated longitudinally extensive myelitic lesions. Diverse neoplasms encountered were found prospectively in 22%. Ovarian teratoma was most common and was predicted best when both N‐methyl‐D‐aspartate receptor–IgG and aquaporin‐4–IgG coexisted (71%). Six patients with prolonged follow‐up had brisk corticosteroid response, but required additional immunosuppression to overcome steroid dependency. Interpretation GFAPα‐IgG, when detected in CSF, is highly specific for an immunotherapy‐responsive autoimmune CNS disorder, sometimes with paraneoplastic cause. Ann Neurol 2017;81:298–309