Atherosclerotic Burden and Remodeling Patterns of the Popliteal Artery as Detected in the Magnetic Resonance Imaging Osteoarthritis Initiative Data Set

Abstract

Background An artificial intelligence vessel segmentation tool, Fully Automated and Robust Analysis Technique for Popliteal Artery Evaluation (FRAPPE), was used to analyze a large databank of popliteal arteries imaged through the OAI (Osteoarthritis Initiative) to study the impact of atherosclerosis risk factors on vessel dimensions and characterize remodeling patterns. Methods and Results Magnetic resonance images from 4668 subjects contributing 9189 popliteal arteries were analyzed using FRAPPE. Age ranged from 45 to 79 years (median, 61), and 58% were women. Mean lumen diameter, mean outer wall diameter, and mean wall thickness (MWT) were measured per artery. Their median values were 5.8 mm (interquartile range, 5.2-6.5 mm), 7.3 mm (interquartile range, 6.7-8.1 mm), and 0.78 mm (interquartile range, 0.73-0.84 mm) respectively. MWT was associated with multiple cardiovascular risk factors, with age (4.2% increase in MWT per 10-year increase in age; 95% CI, 3.9%-4.5%) and sex (8.6% higher MWT in men than women; 95% CI, 7.7%-9.3%) being predominant. On average, lumen and outer wall diameters increased with increasing MWT until the thickness was 0.92 mm for men and 0.84 mm for women. After this point, lumen diameter decreased steadily, more rapidly in men than women (-7.9% versus -6.1% per 25% increase in MWT; P<0.001), with little change in outer wall diameter. Conclusions FRAPPE has enabled the analysis of the large OAI knee magnetic resonance imaging data set, successfully showing that popliteal atherosclerosis is predominantly associated with age and sex. The average vessel remodeling pattern consisted of an early phase of compensatory enlargement, followed by a negative remodeling, which is more pronounced in men.

Trial registration: ClinicalTrials.gov NCT00080171.

Keywords: artificial intelligence; magnetic resonance; popliteal atherosclerosis; remodeling patterns.

Conflict of interest statement

Hippe has received funding from AHA, NIH, GE Healthcare and Philips Healthcare, as well as from Canon Medical Systems USA and Siemens Healthineers. Drs Hatsukami and Yuan have been funded by NIH and Philips Healthcare. The remaining authors have no disclosures to report.

Figures

Figure 1. Three‐dimensional display of segmented artery wall overlaid with original magnetic resonance (MR) image.

Figure 2. Subject flowchart.

Of the 4668 subjects with knee magnetic resonance imaging (MRI), 4521 had bilateral popliteal arteries imaged (9042 arteries) and 147 had 1 popliteal artery imaged, for a total of 9189 arteries. OA indicates osteoarthritis; and OAI, osteoarthritis initiative.

Figure 3. Mean wall thickness across age groups, stratified by sex and risk factors.

Bar heights indicate the median value and error bars indicate the lower and upper quartiles. The risk factors counted were body mass index ≥30 kg/m2, hypertension, diabetes mellitus, prior cardiovascular event, and current smoker.

Figure 4. Popliteal artery remodeling patterns in men and women.

Spline‐smoothed relationships of mean wall thickness with lumen diameter and outer diameter are shown, based on 235 152 and 319 953 cross‐sectional images of men and women, respectively. The shaded regions represent 95% pointwise confidence bands. The vertical regions indicate the thickness where on average the mean lumen diameter tends to decrease with increasing thickness (0.92 mm in men and 0.84 mm in women). WT indicates wall thickness.

Figure 5. Example of a nonatherosclerotic popliteal artery.

Osteoarthritis Initiative (OAI) Case 9000296, left side, baseline (male, 69 years old). A, Magnetic resonance (MR) sagittal view of a knee showing this normal popliteal artery. B, MR axial knee image corresponding to the location marked with a red line on panel A; no wall thickening is observed in this artery.

Figure 6. Example of a diseased, atherosclerotic popliteal artery: OAI (Osteoarthritis Initiative) Case 9894047, right side, baseline (male, 68 years old).

A, Magnetic resonance (MR) sagittal view of a knee showing the thickened vessel wall of this atherosclerotic popliteal artery. B, MR axial knee image corresponding to the location marked with a red line on panel A; the atherosclerotic plaque is clearly seen on the insert. Arrowheads indicate the location of the diseased wall.

Figure 7. The baseline scan of the right side knee of OAI Case 9989700 (female, 74 years old) is used to illustrate the automatic vessel wall segmentation performed by Fully Automated and Robust Analysis Technique for Popliteal Artery Evaluation (FRAPPE).

A, Magnetic resonance (MR) sagittal view of this case that presents a calcified thickened wall. Note that there is more than one piece of calcification in this artery (see arrowheads). B, MR axial knee image corresponding to the location marked with a red line on panel A. Lumen (red) and outer wall (cyan) boundaries are automatically detected by FRAPPE.