Quantification of carotid stenoses using 3D morphometer, CT angiography and conventional angiography

The aim of this study is to compare the performances of 3D morphometer (M3D) regarding the quantification of extracranial carotid stenoses with selective 2D conventional angiography (reference technique) and spiral CT scan.

It is a prospective study, including 15 patients (mean age 75) presenting a symptomatic carotid lesion detected via duplex Doppler to be operated. Patients had to hold their breath for 20 seconds. Twenty-nine carotid bifurcations were studied by means of M3D and 2D conventional angiography (15 patients). Only 10 patients (19 bifurcations) underwent a CT scan. The measures were performed on a visual display unit by measuring the pixels as per the NASCET technique. Diameters (MIP technique) and surfaces (reformated axial slices) were measured.

With MIP technique, a good correlation was found 20 times in 29 (69%) (overestimation: n=8/29) between M3D and angiography, but only in 9 of 19 cases (47%) between CT scan and angiography. Unlike with M3D, the slices re-oriented with CT scan gave better correlations: 15 times in 19 (79%). With the CT scan, the measures were impossible 8 times on MIP technique, and twice on reformated slices for calcified tight stenoses. Therefore, the quantification by means of spiral CT scan is easier by planimetry on slices.

The reliability of these 3D explorations regarding quantification remains uncertain. The use of a morphometer, provided that technical adaptations are made, could replace selective sequences in multiple incidences that become accessible in the post-treatment period, with an acquisition field larger than the one of the CT scan.