A personalized iodine delivery rate-based injection protocol in coronary angiography on photon-counting CT

To propose and validate a personalized iodine delivery rate (IDR) based injection protocol for coronary CT angiography (cCTA) on photon-counting CT.

First, ideal IDR (IDR_IDEAL) was retrospectively calculated for a HU target of 500 in 55 keV image reconstructions. Next, linear regression analysis was performed with IDR_IDEAL and demographic parameters to derive a candidate IDR formula. This was implemented in two validation groups characterized by injection rate (3.5 and 5.0 mL/s). Here, coronary enhancement was quantified and equivalence assessed for a predefined HU range (500 ± 50). Additionally, a reader study assessed perceived enhancement of the coronary tree.

This IRB-approved study used a retrospective cohort of 162 patients (group A: 58 ± 12 years; 81 men) and two prospective cohorts of 51 patients (group B1: 60 ± 13 years; 22 men and group B2: 59 ± 12 years; 30 men). IDR_IDEAL correlated best with fat-free mass (FFM) (r = 0.67) and was integrated for contrast personalization. Prospectively, mean coronary enhancement was 533 ± 97 HU and 528 ± 68 HU for both groups (p = 0.79) with mean IDR values of 1.01 ± 0.11 gI/s and 1.07 ± 0.14 gI/s. However, distribution variances were significantly different (p = 0.015). Subjective scoring showed no differences between the two groups on overall and per-vessel level (p > 0.05).

A personalized, IDR-based injection protocol for cCTA was proposed and validated. FFM was best for IDR_IDEAL prediction. Higher injection rates provided more precise coronary enhancement.

Question Virtual mono-energetic images lead to low iodine delivery rate settings, but the impact on coronary enhancement is not clear. Findings An iodine delivery rate-based injection protocol implementing personalized contrast volume dilutions with set injection duration and high injection rate improved coronary enhancement. Clinical relevance Iodine delivery rate fine-tuning is a promising approach for coronary CT angiography with low iodine volumes. High injection rates provide more accurate and precise coronary enhancement.