Editor’s Choices
Utility of the K-Means Clustering Algorithm in Differentiating Apparent Diffusion Coefficient Values of Benign and Malignant Neck Pathologies• A. Srinivasan, C.J. Galbán, T.D. Johnson, T.L. Chenevert, B.D. Ross, and S.K. Mukherji
What is K-means clustering? It is a statistical technique that allows one to cluster or classify objects according to a common trait. In this study, the authors used this technique in an attempt to classify neck lesions as either benign or malignant according to their ADC values. The reason for this: using isolated ADC values for this same purpose is fraught with difficulty and not always reliable. They retrospectively assessed 10 benign and 10 malignant neck lesions and clustered them into a 2-partition (low and high ADC) or a 3-partition (low, intermediate, and high ADC) model. Results: statistically significant differences were found for benign vs. malignant lesions in both partition models and were also predictive of malignancy. They conclude that clustering of large datasets provides a better characterization of neck lesions when compared to whole-lesion ADC alone.
A Novel Association between RASA1 Mutations and Spinal Arteriovenous Anomalies• R. Thiex, J.B. Mulliken, N. Revencu, L.M. Boon, P.E. Burrows, M. Cordisco, Y. Dwight, E.R. Smith, M. Vikkula, and D.B. Orbach
This wonderful article is destined to become a classic. The association of capillary vascular malformations and spine AVM and/or AVF is newly recognized and due to mutations in the RASA 1 gene located in a long arm of chromosome 5. This new syndrome is called CM-AVM. This gene partly controls vascular cellular proliferation and differentiation. The authors found 5 patients with skin and spine metameric lesions and investigated them for the gene mutation, which they all had. This is the first report of this association, and the authors speculate that similar genetic abnormalities may be responsible for other metameric spinal and cerebral vascular conditions.
Penumbra System: A Novel Mechanical Thrombectomy Device for Large-Vessel Occlusions in Acute Stroke • Z. Kulcsár, C. Bonvin, V.M. Pereira, S. Altrichter, H. Yilmaz, K.O. Lovblad, R. Sztajzel, and D.A. Rüfenacht
Although the Penumbra clot-retrieval device is approved for intracranial use, the authors of this investigation set out to evaluate if it can be used for recanalization of large internal carotid artery occlusions. 27 patients underwent isolated thrombectomy or thrombectomy in combination with pharmacological clot lysis and stent placement. The goals of treatment were improvement of the stenosis, NIHSS grade and outcome. 23 patients had anterior circulation occlusions, and the basilar artery was involved in 4. Adequate recanalization was accomplished in 93% of patients while over 50% of patients showed clinical improvement at discharge. Complete recanalization correlated with favorable outcome and overall mortality was 11%. Conclusion: the Penumbra system shows high potential for recanalization of large arteries.
Fellows’ Journal Club
Negative CT Angiography Findings in Patients with Spontaneous Subarachnoid Hemorrhage: When Is Digital Subtraction Angiography Still Needed? • R. Agid, T. Andersson, H. Almqvist, R.A. Willinsky, S.-K. Lee, K.G. terBrugge, R.I. Farb, and M. Söderman
About 20% of patients with SAH will show no demonstrable underlying cause by catheter angiography. Can CTA be used to exclude an underlying aneurysm instead of conventional angiography? The authors retrospectively identified 193 patients with SAH and negative CTA who also underwent catheter angiograms. They correlated the location of the SAH with findings on CTA and DSA. Acutely only 1 patient had an aneurysm not seen on CTA while on repeat angiography 4 such cases were identified. Five patients, however, experienced complications from DSA. A common cause of SAH with negative CTA was vasculitis. The authors concluded that initial negative CTA findings are reliable in ruling out aneurysm in patients with SAH isolated to the perimesencephalic region but that DSA continues to be needed in patients with initially negative CTA but diffuse SAH. Vasculitis was associated with peripheral SAH.
Optimal Brain Perfusion CT Coverage in Patients with Acute Middle Cerebral Artery Stroke • A.D. Furtado, B.C. Lau, E. Vittinghoff, W.P. Dillon, W.S. Smith, T. Rigby, L. Boussel, and M. Wintermark
More and more institutions rely on CT perfusion instead of MR perfusion due to its ease of access. The extent of brain coverage with some CT units is still limited, and the authors undertook this study to determine the amount of coverage needed to estimate the size of MCA infarctions and the core-penumbra mismatch. 50 acute stroke patients underwent CT perfusion with 16×5 mm slices, and its accuracy and impact were studied. All patients had follow-up studies 3 days to 3 months later. The authors concluded that to determine mismatch and select patients for treatment, coverage of 75 mm is needed, and 50 mm coverage is needed to assess the core infarct. Thus, older CT units that give you only 3 perfusion slices may not be the best to use.
Utility of CT Angiography in the Identification and Characterization of Supraclinoid Internal Carotid Artery Blister Aneurysms • J.R. Gaughen Jr, P. Raghavan, M.E. Jensen, D. Hasan, A.N. Pfeffer, and A.J. Evans
How can those folks from UVA see so many blood-blister like aneurysms when many of us almost never see one? These aneurysms are very rare, but when they bleed the resulting morbidity and mortality are very high. They are difficult to diagnose even with DSA, but these authors evaluated the utility of CTA in their identification and characterization. In a 12-month period they found 6 such patients who underwent CTA and DSA. All patients had SAH and all aneurysms were seen on DSA (gold standard) while only 4 were initially seen on CTA. Therefore, they concluded that if CTA is negative, DSA is still needed to exclude this rare type of aneurysm.
