This study evaluated the feasibility of stress 320 detector CT coronary angiography (CTA) derived transluminal attenuation gradient (TAG320) and contrast opacification (CO) difference to detect hemodynamically significant stenoses as determined by invasive fractional flow reserve (FFR ≤ 0.80). Twenty-seven patients, including 51 vessels on rest CTA were studied. 16 (31 %) vessels were not interpretable on stress CTA largely secondary to motion artefacts. Receiver operating characteristic curve analysis showed a comparable area under the curve (AUC) for rest and stress TAG320 (0.78 and 0.75) which was higher than CTA alone (0.68), and rest and stress CO difference (0.76 and 0.67). Compared with rest CTA, stress CTA demonstrated inferior image quality (Median Likert score 4 vs. 3, P < 0.0001) and required a higher mean radiation exposure (3.2 vs. 5.1 mSv, P < 0.0001). Stress TAG320 and CO difference is less feasible and was not superior in diagnostic performance when compared with rest TAG320 and CO difference.