Diagnostic performance of two corrected transluminal attenuation gradient metrics in coronary CT angiography for the evaluation of significant in-stent restenosis by dual-source CT: a validation study with invasive coronary angiography

To determine the diagnostic potential of transluminal attenuation gradients (TAG) with exclusion of stented coronary segments (TAG-ExS) and TAG-corrected contrast opacification (CCO) excluding stented coronary segments (TAG-CCO-ExS) for the assessment of in-stent restenosis (ISR).TAG-ExS and TAG-CCO-ExS were calculated in 93 coronary arteries with 190 stents. The diagnostic performances and the incremental values of the two metrics to coronary computed tomography angiography (CCTA) were analysed and compared.For all stents and stents3 mm in diameter, TAG-ExS and TAG-CCO-ExS were significantly lower in ≥50% than that in50% of ISR (both p0.05). For stent diameters ≤3 mm, significantly lower TAG-CCO-ExS (p=0.000), but not TAG-ExS (p=0.059), was found in ≥50% than in50% of ISR. Addition of TAG-ExS or TAG-CCO-ExS to CCTA, did not improve the diagnostic accuracy of CCTA significantly (all p0.05). Only TAG-CCO-ExS had a significant impact on CCTA for the reclassifications of ISR (p=0.046) in stent diameters ≤3 mm.TAG-ExS and TAG-CCO-ExS did not provide incremental diagnostic value over CCTA in assessing ISR. TAG-CCO-ExS slightly enhanced the reclassifications of ISR for stents ≤3 mm in diameter.