Diagnostic Accuracy of Perfusion CT in Grading of Gliomas

Abstract

Objectives: To determine the diagnostic accuracy of perfusion CT in grading gliomas taking histopathology as gold standard. Study design: Cross-sectional validation study. Setting: Department of Radiology, Allied/DHQ Hospitals, Faisalabad. Period: Study was carried out over a period of six months from 01-09-2015 to 28-02-2016. Methodology: A total of 105 patients were included in this study. Low radiation dose non contrast CT head was performed to localize the region of interest before obtaining a perfusion scan. For the perfusion scan, 50ml of non ionic contrast is injected at a rate of 4-5ml/sec through an IV line by using an automatic power injector. At 5 seconds into the injection, a cine scan was initiated with the following technique: 80kv,100-120mA and 1 second/ rotation for a duration of 50 seconds. After the initial 50 sec cine scan, 8 more axial images were required, 1 image every 15 seconds for an additional two minutes, thus giving a total acquisition time of 170 sec to assess delayed permeability showing a large heterogeneous lesion with surrounding edema and mass effect on CT brain plain were included in the study. Results: Mean age of the patients was 49.4±16.1 year. There were 69 males (65.7%) and 36 females (34.3%). Comparison of perfusion CT findings versus histopathology in diagnosing high grade gliomas showed positive cases 77 and 95, respectively. Sensitivity, specificity, diagnostic accuracy, positive predictive value and negative predictive value of perfusion CT was 78.9%, 80.0%, 79.0%, 97.4% and 28.6%, respectively. Conclusion: In conclusion, clinically available perfusion imaging tools by using CT can provide additional information regarding brain tumor vascular estimates, which could be useful imaging biomarkers for preoperative glioma grading and angiogenesis assessment and could also be useful for treatment planning and response assessment.