Rashindra Manniesing 1 , Marcel T H Oei 1 , Bram van Ginneken 1 , Mathias Prokop 1 Show Affiliations »
Abstract
PURPOSE: To quantitatively assess whether decreasing total radiation dose of the image acquisition protocol has an effect on cerebral CT perfusion values in patients with acute stroke. MATERIALS AND METHODS: This retrospective study was approved by the institutional ethics committee, and informed consent was waived. Twenty consecutive patients with ischemic stroke who underwent CT perfusion imaging with a 320-detector row CT scanner were included. A standard acquisition protocol was used, which was started 5 seconds after injection of a contrast agent, with a scan at 200 mAs, followed after 4 seconds by 13 scans, one every 2 seconds, at 100 mAs, and then five scans, one every 5 seconds, at 75 mAs. The total examination had an average effective dose of 5.0 mSv. For each patient, a patient-specific digital perfusion phantom was constructed to simulate the same protocol at a lower total dose (0.5-5.0 mSv, with stepped doses of 0.5 mSv). The lowest setting for which the maximum mean difference remained within 5% of the reference standard (at 5.0 mSv) was marked as the optimal setting. At the optimal setting, Pearson correlation coefficients were calculated to assess correlations with the reference values, and paired t tests were performed to compare the means. RESULTS: At 2.5 mSv, the maximum mean differences in values from those of the reference standard were 4.5%, 5.0%, and 1.9%, for cerebral blood flow, cerebral blood volume, and mean transit time, respectively. Pearson correlation coefficients of perfusion values for white matter and gray matter were 0.864-0.917, and all differences were significant (P < .0001). Paired t tests showed no significant differences between the reference standard and optimal settings (P = .089-.923). CONCLUSION: The total dose of a clinical cerebral CT perfusion protocol can be lowered to 2.5 mSv, with only minor quantitative effects on perfusion values. Dose reduction beyond this point resulted in overestimation of perfusion values. © RSNA, 2015.
PURPOSE: To quantitatively assess whether decreasing total radiation dose of the image acquisition protocol has an effect on cerebral CT perfusion values in patients with acute stroke . MATERIALS AND METHODS: This retrospective study was approved by the institutional ethics committee, and informed consent was waived. Twenty consecutive patients with ischemic stroke who underwent CT perfusion imaging with a 320-detector row CT scanner were included. A standard acquisition protocol was used, which was started 5 seconds after injection of a contrast agent, with a scan at 200 mAs, followed after 4 seconds by 13 scans, one every 2 seconds, at 100 mAs, and then five scans, one every 5 seconds, at 75 mAs. The total examination had an average effective dose of 5.0 mSv. For each patient , a patient -specific digital perfusion phantom was constructed to simulate the same protocol at a lower total dose (0.5-5.0 mSv, with stepped doses of 0.5 mSv). The lowest setting for which the maximum mean difference remained within 5% of the reference standard (at 5.0 mSv) was marked as the optimal setting. At the optimal setting, Pearson correlation coefficients were calculated to assess correlations with the reference values, and paired t tests were performed to compare the means. RESULTS: At 2.5 mSv, the maximum mean differences in values from those of the reference standard were 4.5%, 5.0%, and 1.9%, for cerebral blood flow, cerebral blood volume, and mean transit time, respectively. Pearson correlation coefficients of perfusion values for white matter and gray matter were 0.864-0.917, and all differences were significant (P < .0001). Paired t tests showed no significant differences between the reference standard and optimal settings (P = .089-.923). CONCLUSION: The total dose of a clinical cerebral CT perfusion protocol can be lowered to 2.5 mSv, with only minor quantitative effects on perfusion values. Dose reduction beyond this point resulted in overestimation of perfusion values. © RSNA, 2015.
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Year: 2015
PMID： 26114226 DOI： 10.1148/radiol.2015142230
Source DB: PubMed Journal: Radiology ISSN： 0033-8419 Impact factor: 11.105