Editor’s Choices
Identification of Infarct Core and Penumbra in Acute Stroke Using CT Perfusion Source Images • X.-C. Wang, P.-Y. Gao, J. Xue, G.-R. Liu, and L. Ma
Although the core of an infarct is clearly seen on diffusion-weighted imaging and corresponds to the hypodensity seen on initial CT images, it is not clear if source images from CT perfusion can consistently identify it. In this study, the authors imaged 42 patients with CTP (CBV and CBF) and used the source images and perfusion studies to try to identify the core and penumbra, then compared their results with those based on the Alberta Stroke Program Early CT Scores. They found that early arterial phase source images correlated well with ASPECTS on CBF and venous phase source images with ASPECTS on CBV. What does this mean? The hypoattenuated area in the venous source images represents the core whereas the hypoattenuated region on early arterial source images corresponds to the penumbra. Thus, the abnormality is always smaller on the venous phase images because they already incorporate collateral circulation. If this proves to be correct in larger studies, one may only need CT to image the acute stroke patient and it makes me wonder about the future role of MR imaging in the evaluation of the acute stroke patient.
Diffusion-Weighted MR Imaging Derived Apparent Diffusion Coefficient Is Predictive of Clinical Outcome in Primary Central Nervous System Lymphoma • R.F. Barajas Jr, J.L. Rubenstein, J.S. Chang, J. Hwang, and S. Cha
All of us know that in many central nervous system tumors increasing cellularity and MIB index correlate with lower apparent diffusion coefficient values and portray a worse prognosis. In this article, the authors set out to assess if this is also true of primary CNS lymphoma. They measured ADC in enhancing tumor regions in 18 immunocompetent patients with high-grade B-cell lymphomas before chemotherapy. ADCs were then correlated with histologic measurements of cellularity and survival analyses were performed. As expected, ADC measurements were heterogeneous but a correlation between cellular density and ADCs was present. Patients with tumors containing ADCs less than the median value of 692 had a significantly shorter progression-free interval and a shorter overall survival.
Diffuse White Matter Damage Is Absent in Neuromyelitis Optica • F. Aboul-Enein, M. Krssák, R. Höftberger, D. Prayer, and W. Kristoferitsch
It is well known that in most multiple sclerosis patients white matter is diffusely affected even if we cannot see it on conventional MR images. Is the white matter also diffusely involved in neuromyelitis optica (Devic disease)? Because NMO generally affects only the optic nerves and spinal cord even when it is recurrent, the authors postulated that white matter should not be diffusely involved as it is in MS. Using MR spectroscopy (obtained at 3T) they examined the white matter of 8 NMO patients and compared their results with those obtained in 8 healthy controls. They found that the normal-appearing white matter in both NMO patients and controls had similar MRS patterns. Thus, diffuse white matter damage is absent in NMO.
Do Iodinated Contrast Agents Impair Fibrinolysis in Acute Stroke? A Systematic Review • K.A. Dani and K.W. Muir
Non-human studies have shown the presence of iodinated contrast media impairs fibrinolysis of thrombus by thrombolytic agents. Obviously, this would be of significant importance for our neurointerventional colleagues treating acute stroke patients. The authors undertook a meta-analysis of the literature to see if this is true. They queried the Medline and EMBASE databases and found 6 studies in which contrast was used and 12 in which it was not. Conclusion: recanalization rates were similar in those patients who received contrast when compared to those who did not. Apparently they believe this evidence is enough, as they state that a randomized trial would require a prohibitively large number of subjects.
Fellows’ Journal Club
Complications of Particle Embolization of Meningiomas: Frequency, Risk Factors, and Outcome • D.F.M. Carli, M. Sluzewski, G.N. Beute, and W.J. van Rooij
Embolization of meningiomas, particularly those in the skull base, is a fairly common preoperative request. During a 15-year period the authors embolized 201 meningiomas (198 patients), most as an adjunct to surgery or radiosurgery though embolization was the primary form of treatment in 28 instances. They basically assessed the occurrence of 2 complications: neurologic deficits and postembolization death. Complications occurred in 11 patients; 10 were hemorrhagic and required surgery and 1 was ischemic. Two deaths were secondary to the procedure. The only risk factor found was the use of use of small particles. The authors discourage the use of these small particles for preoperative meningioma embolization.
Immediate Anatomic Results after the Endovascular Treatment of Unruptured Intracranial Aneurysms: Analysis of the ATENA Series • L. Pierot, L. Spelle, F. Vitry, and ATENA investigators
Here’s another large aneurysm coil study, predominantly from France, which nicely complements last month’s Fellows’ Journal Club choice and podcast ( S. Gallas, A.C. Januel, A. Pasco, J. Drouineau, J. Gabrillargues, A. Gaston, C. Cognard, and D. Herbreteau. Long-Term Follow-Up of 1036 Cerebral Aneurysms Treated by Bare Coils: A Multicentric Cohort Treated between 1998 and 2003. AJNR Am J Neuroradiol 2009;30:1986-92 originally published online on August 13 2009, 10.3174/ajnr.A1744). In the present study, immediate anatomic results in a large series (694 aneurysms in 622 patients) of unruptured aneurysms treated via endovascular approach were assessed. The results were stratified according to the Montreal scale and showed occlusion in 63%, neck remnants in nearly 23%, and aneurysm remnants in nearly 15%. Results were affected by size of the aneurysm and neck but not by location. The authors concluded that endovascular treatment provided satisfactory occlusion rates.
Postsurgical Intracranial Hypotension: Diagnostic and Prognostic Imaging Findings • D.R. Hadizadeh, A. Kovács, H. Tschampa, R. Kristof, J. Schramm, and H. Urbach
Postoperative intracranial hypotension has been implicated in poor clinical outcomes after uneventful neurosurgical procedures. In this study, the authors describe the imaging findings in patients with symptomatic intracranial hypotension induced by wound suction drainage. They review their experience with 3 patients and also review previously published cases. Sixteen patients were unconscious and showed abnormalities in the brain stem and/or basal ganglia after surgery. Eventually, 4 of them died. All showed findings compatible with CSF loss by CT and/or MR imaging. Conclusion: CT/MR imaging readily characterized postoperative intracranial hypotension and these findings underline the potential danger of wound suction drainage.
Sixty-Four-Section Multidetector CT Angiography of Carotid Arteries: A Systematic Analysis of Image Quality and Artifacts • J.J. Kim, W.P. Dillon, C.M. Glastonbury, J.M. Provenzale, and M. Wintermark
Now that most of us use 64-section CT scanners for our vascular work, it is important to know what image quality to expect and which artifacts may occur. That is exactly what the authors of this article set out to do. They retrospectively reviewed 100 CT angiography studies done for suspected stroke. First they assessed the degree of vascular density in different arterial segments, and then they assessed contrast differences between arteries and veins. They also recorded the presence of 6 artifacts: streaks from metal or slow-flowing contrast in adjacent veins, shoulder streaks, venous reflux, motion, and misregistration. Arterial opacification was good (97%) as was contrast between arteries and veins (86%). The most important artifacts were related to flow and mimicked dissections in 14% of patients. The authors concluded that in more than 95% of cases, 64-section CTA yields high-quality studies. See also in this issue the following article: J.Y. Chen, A.C. Mamourian, S.R. Messe, and R.L. Wolf. Pseudopathologic Brain Parenchymal Enhancement due to Venous Reflux from Left-Sided Injection and Brachiocephalic Vein Narrowing. AJNR Am J Neuroradiol 2010;31:86-87 first published on August 6, 2009 as doi: 10.3174/ajnr.A1688.
