Split-bolus intravenous contrast material injection vs. single-bolus injection in patients following endovascular abdominal aortic repair (EVAR).

Purpose: To investigate the feasibility and accuracy of a split-bolus contrast injection CTA (SB-CTA) compared to a single-bolus injection CTA (SI-CTA) protocol of post-EVAR patients.

Materials And Methods: In this IRB-approved study, patients who underwent SB-CTA and SI-CTA after EVAR were evaluated. Attenuation and contrast-to-noise ratio (CNR) of vessels and parenchymal organs were assessed. Subjective enhancement of vessels, quality of 3D reconstructions, and enhancement phase of parenchymal organs were assessed by two independent readers. Endoleak visibility and incidental findings were evaluated.

Results: Fifty-six patients with SB-CTA and SI-CTA at two different time points after EVAR were included in the study (112 imaging studies, mean age 75 ± 9 years). There was no difference in attenuation and CNR for aorta between SB-CTA and SI-CTA (310 ± 87 vs. 311 ± 80 HU, p = 0.88; 31.1 ± 12.6 vs. 29.0 ± 12.2, p = 0.20), although both were improved in the venous structures and parenchymal organs with SB-CTA (portal vein: 149 ± 33 vs. 88 ± 32 HU, 11.6 ± 5.6 vs. 4.3 ± 3.4; liver: 91 ± 19 vs. 68 ± 20 HU, 4.4 ± 2.8 vs. 2.1 ± 2.0; pancreas: 108 ± 27 vs. 82 ± 23 HU, 6.4 ± 3.1 vs. 3.6 ± 2.4; p < 0.0001). Subjectively, enhancement of veins, liver, spleen, bowel, and kidneys was improved (p < 0.001), while there was no difference for the aorta (p = 0.46) and 3D reconstructions (p = 0.58). None of the 18/56 (32.1%) endoleaks was missed with the SB-CTA. More incidental findings were detected with SB-CTA (158/56) compared to SI-CTA (135/56), p < 0.001. SB-CTA was able to adequately characterize 7/15 (47%) of the findings that needed further evaluation in SI-CTA. 4/15 (26%) incidental findings that were missed with SI-CTA but seen with SB-CTA required further evaluation.

Conclusion: Split-bolus injection CTA in the follow-up of EVAR patients allows reliable visualization of endoleaks with improved subjective and objective image quality.