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Background: Eexploring the limits of CT cranial perfusion scan acquisition intervals and predicting time to peak. Methods: A retrospective analysis was conducted on 45 patients with suspected stroke who underwent brain CTP scans. Different sampling intervals were set based on the TDC. The patients were divided into four groups: Group 1 underwent continuous scanning with a uniform interval of 1.5 s; Group 2 had a uniform interval of 3 s; Group 3 had a 1.5-s interval between arterial and venous peak vertices with 1 point retained before and after the peak for 1.5 s and with a remaining acquisition interval of 4.5 s; and Group 4 had a uniform interval of 4.5 s. Statistical analysis was performed on the perfusion parameters of each group. Additionally, in 286 patients who underwent head and neck CTA examinations, the peak time of contrast medium was recorded, and the peak time was predicted based on factors such as age, height, weight, heart rate, systolic blood pressure, diastolic blood pressure, triglycerides, and total cholesterol. The results compared with Group 1 and Group 2, as well as Group 1 and Group 3, the P values of CBF, CBV, MTT, and Tmax in the left and right cerebral hemispheres of healthy subjects and in the infarct and noninfarct areas of patients were all >0.05. A comparison between Group 1 and Group 4 showed that right cerebral hemisphere CBF and CBV, left cerebral hemisphere CBF, CBV, and Tmax, infarct area CBV and Tmax, and noninfarct area CBF, CBV, and MTT had P values > 0.05, while other groups all had P values < 0.05. BlandâAltman analysis showed that the perfusion parameters in Group 1 were consistent with those in Group 2, and those in Group 1 were consistent with those in Group 3. The radiation doses in the second and third groups were lower, and the dose in the third group was lower than that in the second group. Conclusion: Continuous acquisition between the peak points of the arterial and venous phases, with 1 point reserved before and after the peak and a 4.5-s interval for the rest, represents the maximum time interval for CTP scanning and can effectively reduce the radiation dose. The formula Tmax (s) = 0.290 × height (cm) - 0.226 × heart rate (times/min) + 0.216 × age (years) - 1.901 × triglycerides (mmol/L) - 0.061 × systolic blood pressure (mmHg) - 7.216 (R2 = 0.449, F = 17.905, P < 0.01) was established for predicting time to peak enhancement.
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The aim of this study was to define lower dose parameters (tube load and temporal sampling) for CT perfusion that still preserve the diagnostic efficiency of the derived parametric maps. Ninety stroke CT examinations from four clinical sites with 1 s temporal sampling and a range of tube loads (mAs) (100-180) were studied. Realistic CT noise was retrospectively added to simulate a CT perfusion protocol, with a maximum reduction of 40% tube load (mAs) combined with increased sampling intervals (up to 3 s). Perfusion maps from the original and simulated protocols were compared by: (a) similarity using a voxel-wise Pearson's correlation coefficient r with in-house software; (b) volumetric analysis of the infarcted and hypoperfused volumes using commercial software. Pearson's r values varied for the different perfusion metrics from 0.1 to 0.85. The mean slope of increase and cerebral blood volume present the highest r values, remaining consistently above 0.7 for all protocol versions with 2 s sampling interval. Reduction of the sampling rate from 2 s to 1 s had only modest impacts on a TMAX volume of 0.4 mL (IQR -1-3) (p = 0.04) and core volume of -1.1 mL (IQR -4-0) (p < 0.001), indicating dose savings of 50%, with no practical loss of diagnostic accuracy. The lowest possible dose protocol was 2 s temporal sampling and a tube load of 100 mAs.
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Objective To explore the effects of cranioplasty onneurological functionin patients based on the cerebral CT perfusion technique. Methods Twenty cases of patients receiving cranioplasty were rerecorded during the study period,and they wererespectively scanned by CT perfusion within 72 hours before and 2 weeks after the cranioplasty. Meanwhile,the neurological function was evaluated by neurological function scale. Results The difference of cerebral blood flow before and after cranioplasty was statistically significant(P<0.05), whereas the difference of cerebral blood volume,transit time to the peak and mean transit time was not statistically significant(P>0.05).Correlation analysis showed that the preoperativedifference ratio of thecerebral blood infusio-nis not correlated with the neurological function score(P > 0.05). The changes of preoperative and postoperative difference rateof the cerebral blood infusionwas correlated with the functional independence measure(P < 0.05), whereas not with mini-mental state examination(P > 0.05). Conclusions The neurological function of the patients after cranioplasty may be improved.This improvement may benefit from the improvement of cerebral blood flow after cranioplasty.
