AJNR Blog » stroke

educational presentation: atypical features in pres

MCastillo — Mon, 07 Jun 2010 17:24:37 +0000

Here is another presentation that I hope our readers and visitors will find useful and enjoy. We presented this as an “exhibit” at the past meeting of ASNR. The presentation deals with atypical MRI findings in posterior reversible encephalopathy syndrome.

Radiation Dose in Neuroradiology: New Special Collection and Podcast

MCastillo — Wed, 11 Nov 2009 17:18:03 +0000

By now most Neuroradiologists are aware of the US Food and Drug Administration notification regarding dangerous levels of radiation exposure produced in one facility while performing CT perfusion. This unfortunate event has been front page material for the media, leading to patient anxiety and, more important, to questions regarding the use of this valuable technique. The facility involved has recently revealed that 260 patients were exposed to high radiation levels; 20% of cases involving the eyes which places these individuals at high risk for cataracts. It should come as no surprise that by the time of this writing, legal action against that facility and the equipment manufacturer have been initiated. Shortly thereafter, in a different facility, a technologist scanned the same region of a child’s head 151 times! Because radiation exposure from diagnostic tests has received considerable notice—even before these 2 incidents—it behooves all of us to employ our equipment judiciously. In many instances, the benefits far outweigh the risks of radiation exposure.

In a timely fashion that only electronic publication allows, Drs. Max Wintermark and Mike Lev, experts on CT perfusion, have put together a wonderful editorial (to appear in the print edition of AJNR, too) and an informative Special Collection on radiation exposure-related articles. Our series of Special Collections is biannual but when we believe that our readers and society constituency need further information, we can rapidly act and deploy educational materials that will keep us all well versed and up-to-date.

Additionally at www.ajnr.org you will be able to find our first podcast. Our podcast editor is Dr. Doug Phillips from Cornell University. This podcast is a group discussion regarding radiation exposure and CT scanning. The group participants are Drs. Wintermark, Lev, Schaefer and Sanelli all experts in this field. Before this podcast was recorded I invited all editorial board members of AJNR to send us their questions in order to assure a balanced point of view. The discussants did a great job trying to address the most important issues.

Listen to the Podcast (opens as a mp3).

View the Special Collection.

AJNR Paper Points to Future of Severe Ischemic Stroke Treatment

rggonzalez — Fri, 13 Feb 2009 15:45:00 +0000

Acute ischemic stroke remains the most important neurologic malady in the world. Severe strokes caused by artery occlusion are a minority of all strokes, but cause most of the poor outcomes and costs associated with stroke. Neurointerventionalists have effective therapies, but too few stroke patients undergo endovascular procedures. The reasons are multiple, but a major reason is that patients too frequently arrive beyond the traditional time windows for treatment. A way to break out of this dilemma is described in the paper recently ePublished in the AJNR (N. Janjua, A. El-Gengaihy, J. Pile-Spellman, and A.I. Qureshi Late Endovascular Revascularization in Acute Ischemic Stroke Based on Clinical-Diffusion Mismatch AJNR Am J Neuroradiol first published on February 4, 2009 as doi: 10.3174/ajnr.A1474).

The paper describes a small series of patients who were outside of the traditional stroke therapy window, but underwent endovascular therapy anyway. The majority of the patients had small DWI abnormalities in the setting of significant neurological symptoms (NIHSS greater than 8), a circumstance that has been termed a clinical-diffusion mismatch. Of those who underwent successful revascularization, all had significant clinical improvement, and none had intracerebral hemorrhage. The data makes physiological sense. Patients with major artery occlusions, severe neurological symptoms and small diffusion abormalities must have excellent collateral circulation that is sustaining neuronal viability despite synaptic dysfunction that produces the neurological syndrome.

If the findings described by Janjua et al. are confirmed, it begs the question of how many potential patients may fit the clinical-diffusion mismatch criteria. The number may be quite large as data from another paper by Copen et al. that was also recently ePublished (Existence of the Diffusion-Perfusion Mismatch within 24 Hours after Onset of Acute Stroke: Dependence on Proximal Arterial Occlusion Radiology. 2009 Jan 21. [Epub ahead of print]). Copen et al. found that well over half of all patients with a proximal anterior circulation occlusion had relatively small diffusion abnormalities.

Janjua and his co-authors have made an exceptional contribution to stroke research and I believe are lighting the path towards improved care of patients with the most severe strokes.

Validation and Standardization of Stroke Perfusion Methods

mlev — Thu, 05 Feb 2009 13:01:38 +0000

CTP and MRP acquisition hardware, protocols, post processing, and interpretation vary widely between centers. If we are to use these techniques for rational triage of acute stroke patients to appropriate treatment, validation and standardization is required. I encourage all who perform such imaging to participate in the “STIR” effort, being corrdinated by Max Wintermark et al at UCSF.