1. Sample
This work evaluated a total of 33 hepatic-CT studies, 15 female (45 %) and 18 male (55 %) patients. Observed patient anthropometrics were 73.7 ± 16.1 kg to body weight (BW), 166.0 ± 9.1 cm to body height and 26.7 ± 5.5 to calculated body mass index (BMI).
Patient aged between 30 and 90 years old (66.6 ± 13.9 years old) with the distribution presented in Fig. 2.
Fig. 2: Box plot of the Sample distribution according to patient's age.
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
2. Injection protocol
Injection protocol collected data showed that 3.0 mL/s was the most used flow (91 % of the studies) and venous puncture mostly performed (67%) on the left side of the patient. Venous puncture laterality only influences with statistically significance (t(31) = 2.178, p = 0.037) the arterial portal vein enhancement – patient right-side injections showed higher values when compared with left-side injections (91.4 ± 14.5 and 57.4 ± 8.4, respectively).
The injected volume of ICM presented a short variation, 81.2 ± 5.9 mL, which resulted in an administered ICM dose of 406.1 ± 87.1 mg I/kg BW. As observed in Fig. 3 , the ICM dose showed a strong variability (between 204.2 and 595.7 mg I/kg BW) and strong statistically significant negative correlations with BMI (r = -.779, n = 33, p <.001) and BW (r = -.936, n = 33, p <.001) with significant statistical linear regressions observed (p <.001) in both indicators.
Fig. 3: 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
Fig. 4 resumed pre-established delays selection. As observed, 35 and 40 seconds were the preferable arterial delays and 70 and 80 seconds the preferable portal venous delays.
Fig. 4: Box plot of the sample distribution according to used pre-stablished arterial (blue) and portal venous (orange) delays.
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
3. Structures enhancement
Regarding structures enhancement, there was a statistically significant difference in arterial phase structures enhancement based on the combination of ICM dose and arterial delay used [F(12, 5.58) = 4.72, p = .04; Wilk's Λ = 0.002]. Tests of Between-Subjects Effects showed that this influence occurs mainly in aortic enhancement [F(4, 4) = 20.52, p=.006] and univariate analysis also showed that isolated ICM dose influenced aortic arterial enhancement [F(20,4) = 11.58, p = .014].
Table 3 and Fig. 5 show structures enhancement results based on the most frequent arterial delays. Arterial delay of 35 seconds showed a higher difference between the aorta artery and portal vein enhancement, simultaneous with higher aortic enhancement.
Fig. 5: Box and whisker plot of structures enhancement in arterial phase
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Table 3: Descriptive statistics of the arterial phase enhancement
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Regarding the portal venous phase, there was no statistically significant difference in structures enhancement based on the combination of ICM dose and portal venous delays. On the most frequent used portal venous delays were evident a higher difference between the portal vein and aortic enhancement at 70 seconds when compared with 80 seconds (Fig. 6 and Table 4). However, with used injection protocol, referential minimal portal venous hepatic enhancement (50 HU) only was reached when 80 seconds delay was used.
Fig. 6: Box and whisker plot of structures enhancement in portal venous phase
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT
Table 4: Descriptive statistics of the portal venous phase enhancement
References: School of Health Sciences, University of Aveiro (ESSUA) - Aveiro/PT