Extravascular incidental findings at multislice CT angiography of the abdominal aorta and lower extremity arteries: a retrospective review study

Purpose To assess the frequency and clinical impact of extravascular incidental findings on routine CT angiography of abdominal aorta or lower extremity arteries. Materials and MethodsFrom January 2002 to July 2004, a total of 692 patients underwent CT angiography of abdominal aorta and lower extremity arteries. Two radiologists retrospectively reviewed by consensus cross-sectional images for the presence and clinical impact definition of extravascular findings. The revision of hospital charts, medical records, and all procedures' reports performed before and after CT angiography represented the standard of reference (SOR). Results Only 373 out of 605 patients in whom extravascular findings were found had a SOR; in these patients CT angiography obtained a true-positive incidental rate of 98.9% (369/373). For the clinical impact definition of CT-angiography incidental findings, a concordance with SOR was obtained in 56.3% of patients, whereas a subsequent investigation was required in 183 patients (183/369, 49.6%). Among clinically relevant incidental findings, a total of 35 malignancies (35/894, 3.9%) were detected in 20 patients (20/423, 4.7%); in 15 patients (15/423, 3.5%) malignancy was unknown before CT-angiography exam. Conclusion A careful observation of cross-sectional images, even if "time consuming", is mandatory not only to assess vascular findings but also to avoid a misdiagnosis of clinical relevant extravascular findings.