In the study by von Kiedrowski et al. published in this issue, the clinical utility of 16-slice CT in assessing patients with prior coronary bypass surgery (CABG) is tested. In this retrospective single centre study, the authors describe computed tomography angiography (CTA) findings in the assessment of both the bypass grafts and the native vessels of 39 patients referred for CTA due to chest pain or inconclusive stress tests. Eighteen of those patients were furthermore referred to invasive coronary angiography (CA) after pathologic findings in CTA. This subgroup of patients with both exams performed was used to calculate MSCT accuracy for predicting significant coronary stenosis, defined by a luminal lumen narrowing C50, using CA QCA as the gold standard. Per patient, per graft and per native vessel analyses were made. The authors found a very good overall accuracy of CTA in the assessment of bypass grafts patency/ stenoses and an acceptable accuracy in the native vessel evaluation, with an overall very low rate of false negatives. However, 28.5% of native vessel segments were considered unevaluable. Despite the limitations that result from the retrospective nature of the study, with obvious implications in the interpretation of the results, due to the so-called ‘‘verification bias’’ (that tends to overestimate sensitivity and underestimate specificity of the test), one of the advances of this study is that, differently from previous studies [1], the clinical value of CTA was assessed not only for the graft evaluation but also for the native coronary arteries assessment, namely the non-grafted native arteries and the proximal and distal segments of the bypassed vessels. For a non-invasive study in symptomatic patients after CABG it is important to include the assessment of native coronary arteries, as these may be responsible for the symptoms and their assessment may change treatment [2–4]. However, CT assessment of native coronary arteries in patients after CABG is challenging, owing to the advanced atherosclerotic disease with abundantly calcified and diffusely narrowed arteries with small dimensions [2, 3]. The diameter size, relative immobility and sparce presence of calcifications make grafts ideal for assessment by non-invasive imaging techniques. CT angiography is not limited by some of the practical disadvantages of CA, such as the requirement for selective contrast injection. Particularly when the exact surgical history is incomplete, CT allows comprehensive graft visualization, including the site and identity of distal run-offs [3]. In this study, all Editorial comment to: von Kiedrowski et al. (2008) Noninvasive coronary angiography: the clinical value of multi-slice computed tomography in the assessment of patients with prior coronary bypass surgery. Int J Cardiovasc Imaging. doi: 10.1007/s10554-008-9361-x.