Computed tomography pulmonary angiography in around-the-clock clinical care with individualised scan protocols: a 5-year observational study on incidence and causes of repeat scanning

TL;DR

This study finds that individualized CT scan protocols reduce repeat scans, with most repeat reasons linked to patient factors like age and gender.

Contribution

The study evaluates repeat CT pulmonary angiography scans in real-world clinical care using individualized protocols, identifying patient-related factors as key contributors.

Findings

Repeat CT pulmonary angiography rate was 3.1% over 5 years.

Repeat scans were more common in younger patients and females.

Expert evaluation suggests repeat rates as low as 1.2% may be achievable.

Abstract

Elevated repeat-scanning rates are reported for CT pulmonary angiography (CTPA). Individualised protocols optimise contrast- and radiation-doses, but whether this affects repeat scanning is unknown. The current study evaluates repeat-CTPA in a 24/7, state-of-the-art clinical-care setting.

This is a retrospective observational single-centre study of consecutive CTPA acquired over a 5-year period during standard clinical care. The primary outcome is the repeat-scan rate. Repeat- and single-scan groups were compared for initial-scan characteristics (patient-related, CT-scanner, contrast-administration, kV-settings, regular hours/shifts, radiation-dose), and cumulative contrast- and radiation-doses. An expert radiologist panel retrospectively evaluated probable reasons for repeat scanning through visual, subjective assessment of initial-scan images.

CTPA repeat rate was 3.1% (139/4467). Repeat- and single-scan groups significantly differed: age (55 ± 18 vs. 63 ± 17 years; p < 0.001), Body Mass Index (27 kg/m2 (IQR 7) vs. 25 kg/m2 (IQR 6); p = 0.022), radiation-dose (141 mGy∙cm (IQR 73) vs. 121 mGy∙cm (IQR 70); p < 0.001). Cumulative contrast- and radiation-doses were: 96 mL (IQR 31) vs. 48 mL (IQR 22) (p < 0.001); 0.36 gI/kg (IQR 0.11) vs. 0.18 gI/kg (IQR 0.51) (p < 0.001); 272 mGy∙cm (IQR 69) vs. 121 mGy∙cm (IQR 70) (p < 0.001).

Retrospective expert-consensus reasons for repeat scanning were: 31/133 patient-related; 28/133 multifactorial; 12/133 contrast/scan-protocol; 4/133 operator-error; 2/133 unidentified. 56/133 (42%) initial scans were retrospectively deemed diagnostic-quality, and these significantly differed from other repeat-categories in patient characteristics age (51 ± 15 vs. 57 ± 19 years; p = 0.045) and sex (64.3% vs. 50.6% female; p = 0.045), and in contrast volume (48 mL (IQR 17) vs. 46 mL (IQR 24); p = 0.031).

Individualised scan protocols yielded diagnostic images around the clock, with repeat scanning well within ranges published in the literature. Retrospective expert evaluation suggests repeat rates as low as 1.2% may be possible. Repeat- and single-scan groups significantly differed in patient characteristics, and repeat-scanning reasons were mostly patient-related. These results suggest further tailoring protocols to (younger, female) patients might be beneficial in helping to further reduce CTPA-repeats.

Question
CT pulmonary angiography (CTPA) is subject to relatively high repeat-scanning rates, but it is not known how state-of-the-art CTPA and individualised protocols perform in clinical practice today.

Findings
During 5 years of clinical practice the repeat rate was 3%; retrospective expert image-evaluation suggests a repeat rate as low as 1.2% may be possible.

Clinical relevance
Repeat- and single-scan groups significantly differed in patient characteristics, and reasons for repeat scanning were mostly patient-related. Further tailoring protocols to (younger, female) patients may be the best focus to help reduce CTPA-repeats, improve safety, and reduce logistic burden.

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