RESUMO
The accuracy of 16-row multidetector CT in the visualization of different peripheral artery stents and in the appraisal of in-stent stenosis was assessed. Nine different stent types (nitinol and stainless steel) with three diameters (6, 8 and 10 mm) were used; altogether 27 stents were analyzed in a barrel-shaped vascular model. Low-grade (<40%) and high-grade (>60%) in-stent stenoses were simulated by polyurethane sticks (70 HU) of differing diameters (2-6 mm). Imaging was performed with 16x0.75-mm detector collimation, 130 mAs, 120 kV, 12-mm table feed/rotation, 1.0-mm slice thickness and 0.5-mm increment. The stent diameter, strut thickness, in-stent attenuation values, degree and degree of in-stent stenosis were evaluated. Nitinol stents showed significantly (P<10-6) less stent lumen narrowing, artificial strut thickening and overestimation of the degree of in-stent stenoses than stainless steel stents. In-stent attenuation values and artificial strut thickening were significantly (P<10-6) lower in 10- and 8-mm stents than in 6-mm stents. Stent lumen narrowing was significantly less in 10-mm stents than in 8-mm (P<10-4) or 6-mm (P<10-6) stents. In-stent stenoses were significantly overestimated, irrespective of the stent diameter. In 6-mm stents overestimation was significantly higher than in 8-mm (P<0.01) or 10-mm stents (P<10-6). Under in-vitro conditions 16-row MDCT allowed an accurate identification of in-stent stenosis, but significantly overestimated the effective degree of the stenosis.
