Accuracy of Non-Enhanced CT in Detecting Early Ischemic Edema Using Frequency Selective Non-Linear Blending |
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Authors: | Georg Bier Malte N Bongers Hendrik Ditt Benjamin Bender Ulrike Ernemann Marius Horger |
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Institution: | 1. Department of Diagnostic and Interventional Radiology, Eberhard Karls-University Tuebingen, D-72076, Tuebingen, Germany;2. Siemens AG Healthcare, Imaging & Therapy Systems Computed Tomography & Radiation Oncology, Siemensstr. 1, D-91301, Forchheim, Germany;3. Department of Neuroradiology, Eberhard Karls-University Tuebingen, D-72076, Tuebingen, Germany;INSERM U894, FRANCE |
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Abstract: | PurposeIschemic brain edema is subtle and hard to detect by computed tomography within the first hours of stroke onset. We hypothesize that non-enhanced CT (NECT) post-processing with frequency-selective non-linear blending (“best contrast”/BC) increases its accuracy in detecting edema and irreversible tissue damage (infarction).MethodsWe retrospectively analyzed the NECT scans of 76 consecutive patients with ischemic stroke (exclusively middle cerebral artery territory—MCA) before and after post-processing with BC both at baseline before reperfusion therapy and at follow-up (5.73±12.74 days after stroke onset) using the Alberta Stroke Program Early CT Score (ASPECTS). We assessed the differences in ASPECTS between unprocessed and post-processed images and calculated sensitivity, specificity, and predictive values of baseline NECT using follow-up CT serving as reference standard for brain infarction.ResultsNECT detected brain tissue hypoattenuation in 35 of 76 patients (46.1%). This number increased to 71 patients (93.4%) after post-processing with BC. Follow-up NECT confirmed brain infarctions in 65 patients (85.5%; p = 0.012). Post-processing increased the sensitivity of NECT for brain infarction from 35/65 (54%) to 65/65 (100%), decreased its specificity from 11/11 (100%) to 7/11 (64%), its positive predictive value (PPV) from 35/35 (100%) to 65/69 (94%) and increased its accuracy 46/76 (61%) to 72/76 (95%).ConclusionsThis post-hoc analysis suggests that post-processing of NECT with BC may increase its sensitivity for ischemic brain damage significantly. |
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