Résumé
Objective To evaluate the reliability of CT perfusion parameter values of the normal hepatic segments and neoplasms, obtained with deconvolution (DC) and maximum slope (MS) algorithms. Methods Perfusion parameter values of 111 ROIs in 62 normal hepatic segments and 49 neoplasms derived from 62 CT perfusion studies performed with 320 multi-slice CT, were retrospectively analyzed by two experienced radiologists. BF,BV and PI according to DC and MS algorithms were compared with t paired test, Pearson correlation and Bland-Altman agreement analysis. Interobserver agreement for all perfusion parameters was calculated using intraclass correlation coefficients (ICC). Results Interobserver agreement measured with ICC was very good for all perfusion parameters (≥0.95). BFdc and BVdc exceeded the BFms and BVms in normal hepatic segments and neoplasms (P0.05). Both pairs of perfusion measurements significantly correlated with each other(r>0.9, P<0.01),but the agreement of BF, BV and PI according to DC and MS algorithms was not good. Conclusions CT perfusion values such as BF,BV and PI obtained by DC and MS algorithms correlated significantly with each other, but with poor agreement.
Résumé
Objective To evaluate the feasibility of optimized scan protocol in whole-brain perfusion imaging with 320-MDCT scanner.Methods Twenty healthy volunteers were randomly divided into control group (13 patients) and test group (7 patients).The standard perfusion scan protocol (collecting 19 volumes)was applied in control group.The optimized perfusion CT scan protocol(collecting ll volumes)formulated by reducing scanning phases reasonably and changing the collection intervals was applied in test group.The regions of interest(ROI) with area of(20 ± 2)mm2 were located in the bilateral frontal white matter,parietal white matter,centrum semiovate,basal ganglia,occipital lobe and cerebellum.Bilateral perfusion values from ROI were measured,including cerebral blood volume(CBV),mean transit time (TTP),cerebral blood flow (CBF),mean transit time (MTT) and delay time (DT).Results Dose length product (DLP)and effective dose (ED)in optimized protocol were decreased 42.02％ as compared to control group.Every relative perfusion value of both sides from both groups were not statistically significant (P ＞ 0.05).Every relative perfusion parameters from individual territory in both groups showed no significant differences (P ＞ 0.05).Conclusions Using the optimized scan protocol,we could obtain the same whole-brain perfusion values could be obtained with the default standard protocol and less radiation dose.