Articles from Stroke journal November 2008

Link to journal
Schaefer, Pamela W. ; Barak, Elizabeth R. ; Kamalian, Shahmir ; Gharai, Leila Rezai et al
Quantitative Assessment of Core/Penumbra Mismatch in Acute Stroke: CT and MR Perfusion Imaging Are Strongly Correlated When Sufficient Brain Volume Is Imaged
Stroke. 39(11):2986-2992, November 2008.
Abstract
Background and Purpose-: Our purpose was to determine (1) the correlation between quantitative CT and MR measurements of infarct core, penumbra, and mismatch; and (2) whether the difference between these measurements would alter patient selection for stroke clinical trials.Methods-: We studied 45 patients with acute middle cerebral artery stroke imaged a mean of 3.8 hours after onset (range, 0.48 to 8.35 hours) who underwent CT perfusion and MR diffusion (DWI)/perfusion imaging within 3 hours of each other. The DWI and MR-mean transit time (MTT) abnormalities were visually segmented using a semiautomated commercial analysis program. The CT-cerebral blood volume) and CT-MTT lesions were automatically segmented using a relative cerebral blood volume threshold of 0.56 and a relative MTT threshold of 1.50 on commercially available software. Percent mismatch was defined as [(MTT-DWI)/DWI volume]x100. Pearson correlation coefficients were calculated.Results-: There were significant correlations for DWI versus CT-cerebral blood volume lesion volumes (r2=0.88, P<0.001), r2="0.86," r2="0.81,">=100 mL in 41 of 45 (91.1%); (2) MTT lesion size <>2 cm diameter in 42 of 45 (93.3%); (3) mismatch <>20% in 41 of 45 (91.1%); and (4) inclusion versus exclusion from trial enrollment in 38 of 45 (84.4%) patients. Six of 7 disagreements were due to inadequate CT coverage.Conclusion-: Advanced MR and CT perfusion imaging measurements of core/penumbra mismatch for patient selection in stroke trials are highly correlated when CT perfusion coverage is sufficient to include most of the ischemic region. Although MR is currently the preferred imaging method for determining core and penumbra, CT perfusion is comparable and potentially more available.


Ward, R Parker ; Lammertin, Georgeanne; Virnich, Daniel E. ; Polonsky, Tamar S. ; Lang, Roberto M. et al
Use of Carotid Intima-Media Thickness to Identify Patients With Ischemic Stroke and Transient Ischemic Attack With Low Yield of Cardiovascular Sources of Embolus on Transesophageal Echocardiography
Stroke. 39(11):2969-2974, November 2008.
Abstract
Background and Purpose-: Carotid intima-media thickness (CIMT) is associated with systemic atherosclerosis and cardioembolic conditions and predicts the risk of recurrent strokes. We sought to establish the relationship between CIMT and cardiovascular sources of embolus (CSE) on transesophageal echocardiography (TEE) and hypothesized that a noninvasive strategy of CIMT assessment and transthoracic echocardiography bubble study would identify patients with ischemic stroke or transient ischemic attack in whom TEE would provide little incremental diagnostic yield.Methods-: In 180 patients with ischemic stroke or transient ischemic attack of undetermined origin referred for TEE, we prospectively performed CIMT measurement/plaque screen (Phase 1, n=96) or CIMT measurement/plaque screen and transthoracic echocardiography bubble study (Phase 2, n=84) before TEE. Phase 1 results were used to construct receiver operating characteristic curves to demonstrate the ability of CIMT to detect CSE on TEE and to identify the optimal CIMT cutoff value for prospective strategy testing (Phase 2).Results-: In Phase 1, CIMT was found to correlate with TEE markers of aortic atherosclerosis, including complex aortic plaques, and combined CSE. The optimal CIMT cutoff for detection of CSE on TEE was 0.78 mm. In Phase 2, a positive noninvasive strategy test (CIMT >=0.78 mm, +carotid plaque, and/or a positive transthoracic echocardiography bubble study) was present in 61%. The prevalence of CSE on TEE was significantly higher among those with a positive compared with a negative noninvasive strategy test (65% versus 9%, P<0.001),>