Background/Purpose:

Thickening of the aortic wall, probably the earliest CT sign of aortitis, is frequently missed as there are no accepted criteria for normal aortic wall thickness (AWT). Studies based on CT-assessed AWT in healthy persons and patients with prevalent co-morbidities are scarce, and do not allow determination of reference values for the definition of increased AWT necessary for the diagnosis of aortitis by CT. On the other hand, the substantial difference in the techniques of MRI and CT prevent the blind extrapolation of MRI-based definitions onto CT imaging. The present study was conducted to assess the relationship of CT-measured AWT with patient-related and disease-related factors in a large cohort of patients without aortitis.

Methods:

CT scans of 100 consecutive patients without known aortic disease, hospitalized at the Bnai Zion Medical Center were reviewed and AWT measured at three levels: 1. thoracic descending aorta at the level of the bifurcation of the pulmonary artery; 2. abdominal aorta at the level of celiac artery origin; 3. abdominal aorta one slice below the level of the origin of renal arteries. Patients’ charts were analyzed and demographic data and data on co-morbidities extracted. Correlations with measured AWT were calculated.

Results:

By bivariate analysis, AWT had significant positive correlation with patient age (r=0.68, p=0.000; r=0.6, p=0.000; r=0.62, p=0.000, for 3 levels, respectively), the presence of arterial hypertension (2.11±0.6 mm vs 1.7±0.8 mm, p=0.001; 2.14±0.8 mm vs 1.64±0.5 mm, p=0.004; 2.05±0.7 mm vs 1.51±0.6 mm, p=0.000, for 3 levels, respectively) and calcifications of the aortic wall (2.24±0.6 mm vs 1.63±0.7 mm, p=0.000; 2.3±0.8 mm vs 1.58±0.5 mm, p=0.000; 2.16±0.7 mm vs 1.52±0.6 mm, p=0.000, for the 3 levels, respectively). The aortic wall had a tendency to be thicker in males (2.04±0.8 mm vs 1.79±0.6 mm, p=0.089; 2.00±0.6 mm vs 1.85±0.8 mm, p=0.325; 1.95±0.7 mm vs 1.69±0.7 mm, p=0.071, for the 3 levels, respectively) and in patients with known coronary artery disease (2.18±0.6 mm vs 1.86±0.7 mm, p=0.04; 2.11±0.7 mm vs 1.76±0.72 mm, p=0.069; 2.21±0.6 mm vs 1.86±0.76 mm, p=0.073, for the 3 levels, respectively), being independent on the presence of diabetes mellitus, hyperlipidemia or malignancies. Multivariate analysis showed significant positive correlation of AWT only with patient age and the presence of aortic calcifications (p=0,000 and p=0.034 for the thoracic descending aorta, p=0.021 and 0.001 for the upper abdominal aorta, p=0.001 and p=0.005 for the infrarenal abdominal aorta, respectively).

Table 1. AWT in different age groups

AWT in mm (median, range)	<50 years median 40.5 years (16 patients)	50-59 years median 54 years (11 patients)	60-69 years median 64 years (15 patients)	70-79 years median 74 years (33 patients)	≥80 years median 84.5 years (25 patients)
Level 1	1.3 (0.5 – 2.05)	1.4 (0.15 – 1.8)	1.65 (1.3 – 4.75)	2.05 (0.5 – 2.85)	2.38 (1.6 – 2.85)
Level 2	1.4 (0.5 – 1.75)	1.55 (0.2 – 1.7)	1.7 (1.25 – 5.95)	2.15 (0.75 – 3.0)	2.33 (0.7 – 3.05)
Level 3	1.2 (0.5 – 1.75)	1.4 (0.9 – 1.5)	1.5 (1.0 – 5.4)	2 (1.2 – 3.0)	2.1 (1.2 – 4.1)

Conclusion: The ‘normal’ range of AWT varies with age, and may also vary with co-morbidities. These data may serve as a reference and should be considered in interpretation of the CT-appearance of the aortic wall when assessing for aortitis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/aortic-wall-thickness-in-patients-without-aortitis-a-computed-tomography-based-study-of-100-patients/