Evaluation of peripheral atherosclerosis: a comparative analysis of angiography and intravascular ultrasound imaging

Abstract

Objective: Angiography remains a critical component for diagnostic imaging and therapeutic intervention in peripheral arterial disease (PAD). The goal of this study was to compare angiography with corresponding intravascular ultrasound (IVUS) imaging of the same vessels in patients with PAD.

Methods: From 2004 to 2008, 93 patients undergoing angiography for PAD were recruited in a prospective observational analysis. At the time of angiography, diseased lower extremities were interrogated using a 10-cm IVUS pullback with registration points. IVUS data were analyzed with radiofrequency techniques for vessel and lumen diameter, plaque volume, plaque composition, and cross-sectional area. Similarly, three vascular surgeons blinded to the IVUS data graded corresponding angiographic images according to vessel diameter, degree of stenosis, degree of calcification, and extent of eccentricity. Statistical analyses of matched IVUS images and angiograms were performed.

Results: The distribution of demographic and risk variables were typical for PAD: 54% male, 96% hypertension, 78% hyperlipidemia, 44% diabetic, 87% tobacco history, 65% coronary artery disease, and 10% end-stage renal disease. Symptoms precipitating the angiographic evaluation included claudication (53%), rest pain (18%), and tissue loss (29%). Angiographic and IVUS interpretation were similar for luminal diameters, but external vessel diameter was greater by IVUS imaging (7.0 +/- 0.7 vs 5.2 +/- 0.8 mm, P < .05). The two-dimensional diameter method resulted in a significant correlation for stenosis determination (r = 0.84); however, IVUS determination of vessel area stenosis was greater by 10% (95% confidence interval, 0.3%-21%, P < .05). IVUS imaging indicated that a higher proportion of plaques were concentric. Grading of calcification was moderate to severe in 40% by angiography but in only 7% by IVUS (P < .05).

Conclusions: In the evaluation of PAD, angiography and IVUS imaging provide similar luminal diameters and diameter-reducing stenosis measurements. Determination of overall vessel diameter and interpretation of plaque morphology by angiography are discordant from IVUS-derived data.

Figure 1

Inter-rater concordance among angiographic examiners for determining maximal percent stenosis. Open circles represent actual measured data points among examiners, and the solid black represents the linear regression through those points. The hashed red line represents the 95% confidence interval.

Figure 2

An example of angiographic and intravascular ultrasound (IVUS) analysis. The angiogram is shown in 2A, and the large white arrow marks the area for analysis. This was interpreted as a 30% stenosis based on the angiogram. Figure 2B illustrates the IVUS grey scale imaging through this area. The yellow line marks the internal elastic lamina, and the red line marks the external elastic lamina. By IVUS, this represents a 76% area stenosis. Figure 2C represents the Virtual Histology analysis. The dark and light green shades denote fibrous plaque, which accounts for the majority of this lesion. Red areas represent necrotic plaque, and white areas denote calcium.