1. Injection protocol and monitor phase analysis
The injected ICM volume averaged 94.7 ± 10.6 mL, which resulted in an administered ICM dose of 530.7 ± 79.4 mg I/kg BW. ICM dose showed a strong statistically significant negative correlation with BMI (r = -.657, n = 38, p <.001) and BW (r = -.815, n = 38, p <.001). Those correlations presented statistically significant linear regressions (p <.001) as observed in Fig. 4.
Fig. 4: Scatter plot of correlation between ICM contrast dose and patient body indicators (BW - Body weight and BMI - Body mass index) with calculated linear regressions.
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Injection flow and ICM dose analysis showed no influence in the last aortic monitoring ROI value (p = .639).
Last aortic monitoring ROI presented a strong variability (163.9 ± 74.9 HU), perhaps, median (139.2 HU) showed that results were tendentially closer to the pre-established threshold (100 HU).
Manual trigger bolus tracking was used in 64 % of the hepatic CT examinations. As observed in Fig. 5, trigger methods presented no statistically significant differences concerning the last monitoring aortic ROI value.
Fig. 5: Box and whisker plot of aortic monitor ROI value (automatic vs manual trigger)
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Results of the monitor variables were resumed in Table 1.
Table 1: Resume of the monitor variables results
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Arterial delays averaged 37.0 ± 9.4 s and ranged between 21.0 and 65.5 seconds. Portal delays averaged 77.0 ± 9.3 s and ranged between 61.0 and 105.5 seconds.
2. Structures Enhancement Analysis
Table 2 resumed structures enhancement results. DD influenced, with statistically significance, aortic (p = .046) and hepatic parenchyma (p = .040) arterial enhancement.
Table 2: Resume of the structures enhancement according to used diagnostic delays.
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Fig. 6 shows the arterial structures' enhancement according to the used DD. As observed, 4, 5 and 6 seconds DD values showed lower aortic enhancement, and after 7 seconds it led to steady over 310 HU. Concerning the portal vein and hepatic parenchyma enhancement, 10 and 14 seconds DD values presented increased enhancement values.
Fig. 6: Chart of the arterial enhancement of the structures according to the used diagnostic delay
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
In the portal venous phase, aortic and portal vein enhancement presented a strong variability along with the DD values. In hepatic parenchyma analysis, even if no statistically significant variation was observed, it tended to present an increased enhancement with higher DD values.
As expected, the aortic monitoring ROI value presented a statistically significant Pearson correlation with aortic arterial enhancement (p = .004) which presented a statistically significant Pearson correlation with the portal vein and hepatic parenchyma portal venous enhancements (respectively p = .001 and p = .006).
Also, aortic monitor ROI value influenced, with statistically significance, the portal hepatic parenchyma enhancement (p <.001).
3. Dose impact of the bolus tracking use
DLP associated with bolus-tracking was 18.5 ± 9.9 mGy, on average 1.7 ± 1.0 % of the total DLP (Table 3).
Table 3: Descriptive statistics of the exposure dose
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT