Introduction:
Aortic calcification can be utilized to assess cardiovascular risk. While contrast is useful for vascular enhancement in diagnostic imaging, enhancement creates heterogeneity between post and non-contrast scans and limits their direct comparability.
Hypothesis:
We hypothesized that post and non-contrast aortic calcification measures will correlate, and a correction score can be developed for statistical comparability.
Methods:
Retrospective CT-scans were obtained from the University of Michigan. Participants (N=330) received abdominal scans with and without contrast enhancement within 120 calendar days. Analytic Morphomics was used to obtain vertebral-indexed measurements of aortic calcium area, and aortic wall obfuscation percentage. Calcification was specifically identified as regions with a given morphology and pixel value five standard deviations above the defined central lumen zone. Pearson correlation and multiple linear regression were used to explain the relationship between aortic measurements with and without contrast. Regressions include calcification percent (Model 1), and area (Model 2). Independent variables were non-contrast measurements and dependent variables were contrast measurements, age, and sex.
Results:
Correlations of calcification percent ranged from 0.86 at T11 and 0.94 and L2. Correlations of calcification area ranged from 0.66 at T12 to 0.84 at L3. In Model 1, for every percent increase in post-contrast calcification, non-contrast calcification percent increased by 11% (β=1.11, p <0.001, R2=0.85). In Model 2, for every mm2 increase in post-contrast calcification area, non-contrast calcification area increased by 0.45 mm2 (β=1.45, p <0.001, R2=0.69). Variance inflation factor for Model 1 was 1.08 and 1.07 for Model 2.
Conclusion:
In conclusion, this research proposes a correction score for comparisons of abdominal aortic calcification measurements in post-contrast and non-contrast scans.