CT angiography of thoracic outlet syndrome: Evaluation of imaging protocols for the detection of arterial stenosis

Purpose: The purpose of this work was to evaluate the results of cross-sect ional imaging and multiplanar and 3D reconstructions for the detection of t horacic outlet arterial stenosis on CT angiograms. Method: Eighty-two patients were prospectively evaluated with CT angiograph y: in the neutral position and after postural maneuver (164 acquisitions); with contralateral injection of a 24% (Group 1; n = 68) or 30% (Group 2; n = 96) contrast agent; and reconstruction of four sets of images from each a cquisition, that is, transverse CT scans, sagittal reformations, and 3D [sh aded surface displays (SSD) and volume-rendered (VR)] images. A total of 65 6 sets of images were blindly and independently interpreted by three reader s of variable experience. A consensus interpretation of the four sets of im ages of each acquisition was used as a standard of reference. Results: The number of examinations coded with an excellent degree of arter ial enhancement was significantly higher in Group 2 than in Group 1 [68 (71 %) vs. 35 (51%); p < 0.001]. The sensitivity and specificity for detection of arterial stenosis were 67 and 96% for transverse CT scans, 69 and 94% fo r sagittal reformations, 71 and 99% for 3D-SSDs, and 95 and 100% for VR ima ges. Compared with the standard of reference, a concordant scoring of arter ial stenosis severity was found in 54% of transverse CT scans, 84% of sagit tal reformations, 78% of 3D-SSDs, and 91% of VR images. Underestimation of stenosis was found in 43% of transverse CT scans and 10% of sagittal reform ations; overestimation of stenosis was more frequent on 3D-SSDs (16%) than on VR images (7%). The reader's experience was marked for the interpretatio n of cross-sectional images but did not influence the interpretation of 3D images. Conclusion: Thoracic outlet arterial compression is best depicted with the injection of a 30% contrast agent and reconstruction of VR images.