MO547: A Novel Quantitative Computer-Assisted Score can Improve Repeatability in the Estimate of Vascular Calcifications at the Abdominal Aorta
Authors: Fusaro Maria , Luigi Tripepi Giovanni , Aghi Andrea , Politi Cristina , Crimi Gianluigi , Bazzocchi Alberto , Girolami Marco , Sella Stefania , Barbanti Brodano Giovanni , Schileo Enrico , Taddei Fulvia 
Published: May 2022

Abstract

BACKGROUND AND AIMS
Vascular calcifications (VCs), a known risk factor for cardiovascular disease and mortality, are strongly linked to vertebral fractures (VFs) [1]. The coronary calcium score from computer tomography (CT) is the gold standard to measure VCs [2], but this implies high radiation doses and costs. Although, several calcifications scores at the abdominal aorta have been developed from lower-dose and low-cost lateral spine RX projections. These scores are widely applied (the 0–24 score): Kauppila Score (KS) [3]. Most RX scores are semi-quantitative implying an error-prone visual assessment. Indeed, so far, repeatability studies could not estimate the minimum detectable difference (MDD).
Based on this knowledge, we developed a new RX-based computer-assisted VCs score with the aim to test its precision (repeatability and reproducibility metrics and MDD estimate) compared to KS.

METHOD
New Quantitative Score (QS), computer-assisted tracking of calcifications, considers both abdominal aorta calcification and column length (range 0–1), then multiplied by 24 to easily compare with the standard score: KS.
Dedicated software developed with ALBA framework (https://github.com/IOR-BIC/ALBA) to subsequently record standard and new scores (see Figure 1). We enrolled 44 patients with VCs from an earlier study and the anonymous recorded data were randomized in two series. Five experts from four specialties in two institutions evaluated the data twice, with 1-month interval between series. Additional test-retest evaluation was performed on eight subjects with a second RX within 2 weeks.

RESULTS
Intra-observer analysis (Bland-Altman plots and regression analysis between series): both scores seem not biased; QS showed higher reproducibility [95% confidence interval (95% CI) of differences almost halved].
Inter-observer [Intra Class Correlation Coefficient (ICC)]: ICC higher for QS in the first series (0.78 versus 0.64); a lower difference was observed in the second evaluation (0.84 versus 0.82).
MDD (Standard Error of the Mean): reduced by around 25% for the QS (2.98 versus 4, in the 0–24 scale).
Test-retest (Wilcoxon paired test): not significantly different for both scores.
Agreement (Bland-Altman plots): scores are discordant. The QS shows significantly higher values and an increasing trend with calcification severity.

CONCLUSION
Our new quantitative computer-assisted score improved the precision of RX scores in the estimate of VCs. Furthermore, it showed higher intra-observer repeatability than KS and we reported for the first time an estimate of MDD in the VCs assessment. In detail, MDD was 25% lower for the new score.
An ongoing study will determine whether this lower MDD may reduce follow-up times to check for VCs progression and whether this new VCs score may act as a risk alert for the development/worsening of VFs.