Abstract Background: Electrocardiogram (ECG), stress ECG, myocardial scintigraphy and selective coronary angiography (SCA) are the most frequently used diagnostic tools for examination of patients with suspected ischemic heart disease. The aim of this study was to see if coronary computed tomographic angiography (coronary CTA), a noninvasive modality, may be more widely used in the examination of patients with suspected coronary artery disease, and what the challenges are. Material and methods: The introduction is mainly based on the book “Clinical cardiac CT: anatomy and function” by E. J. Halpern and nonsystematic search through PubMed. 33 patients were included in the study. Criteria for inclusion were non-diagnostic segments or segments with suspected stenoses after having been examined with CT. Four patients were examined with calcium score and SCA. 29 underwent coronary CTA, 28 of these (365 coronary artery segments) were also examined with SCA. Results: 129 of 365 (35.3%) of the segments had uncertain patency after having been examined by the use of coronary CTA. SCA found stenoses in 8.5% (n=11) of these 129 segments. The reason for non-diagnostic segments by CTA was hypoplastic segments in five (2.7%), calcifications in 85 (46.7%), movement artifacts in 30 (16.5%), small amount of contrast in 31 (17.0%), and low mAs in 31 (17.0%).Conclusion: When non-diagnostic CTA examinations were reviewed, calcified coronary plaques were the most frequent finding in the coronary artery segments that limited CTA to give a definite diagnosis. SCA was the best tool for examining these segments. Unfortunately SCA is linked with more serious adverse events than coronary CTA. Therefore present technology of CTA may be used to verify the absence of coronary artery stenoses rather than to prove their presence. Consequently, CTA may replace SCA in some patients and myocardial scintigraphy in many patients.