The challenging patient

In the past decade, coronary CT angiography (CCTA) has established itself as a robust imaging technique for the exclusion of coronary artery disease (CAD) in patients presenting with acute chest pain and moderate cardiovascular risk due to its high sensitivity and negative predictive value in detecting significant coronary artery stenosis. Noninvasive CCTA has become a reliable alternative to inva- sive angiography and, thanks to recent technical innova- tions, has raised its power from just a morphological evaluation to a more comprehensive morphological and functional assessment. Specifically, novel CT technological advancements such as CT myocardial perfusion imaging (CT-MPI) provide a reliable functional analysis of the heart capable of accurately presenting hemodynamically significant coronary artery stenosis. CCTA coupled with CT-MPI could raise CT as the stand-alone image modality for a com-prehensive evaluation of CAD and direct assessment of myo- cardial ischemia in a single examination. Technically speaking, CCTA presents a greater challenge and is more demanding than other CT applications due to the nature of its target, the continuously moving heart. Thus, higher spatial and temporal resolutions are mandatory for a proper visualization of small-caliber vessels such as cor- onary arteries. In addition, image acquisition should be syn- chronized with the patient’s electrocardiogram (ECG) in order to achieve optimal image quality. Due to its technical com- plexity, the accurate selection and preparation of the patient are mandatory for obtaining a high-level examination. Despite the continuous technological advances that have unleashed the diagnostic power of CCTA and allowed accu- rate diagnoses even in difficult clinical scenarios, some minor limitations should still be taken into account when performing CCTA examinations. The comprehensive defini- tion of a challenging patient embraces some clinical condi- tions that should be investigated in order to always guarantee a safe and accurate CT examination.