Table 1 Different causes of abnormal contrast flow, key imaging findings and solutions to obtain a diagnostic CTA

Access cannula and vein mismatch

1. Suboptimal target vessel opacification

2. Injection flow rate may be lower than planned

1. New cannula or access vein

2. When access veins are small: Dual energy scan with 50–60 keV monoenergetic reconstruction

Incorrectly placed region of interest

1. Assess location of region of interest from the bolus tracker/ bolus timing images

Correct placement of ROI, reinjection, and reimage

Extravasation

1. No target vessel opacification

2. Contrast presence in soft tissues of access vein extremity

1. New cannula and access vein at a different site

Thoracic venous outlet obstruction

1. Contrast pooling in the collaterals around axilla & chest wall

1. Asymptomatic: reinjection with arm down position

2. Symptomatic: new access site in contralateral extremity

Transient interruption of contrast bolus

1. Transient decreased contrast attenuation.

2. Presence of normal contrast in upstream vessels

1. Shallow breath hold

2. End expiratory imaging

3. Free breathing high pitch acquisition

Differential enhancement in pulmonary artery

1. Delayed acquisition

2. Biphasic injection

Differential enhancement in aorta

1. Multiplanar reformats to evaluate coarctation, shunts.

Mixing artifact in aorta

Contrast blood level, dependent pooling of contrast

1. Assessment of cardiac function Repeat delayed (30 sec) limited Z axis scan

Mixing artifact in left atrium

Contrast blood level in left atrium, pulmonary veins

Assessment of cardiac function

Poor opacification of left ventricle

No opacification of left ventricle on a pulmonary artery CTA

Assessment of cardiac function

Early enhancement on left compared to right heart

Intracardiac shunt

Assessment of cardiac function

Asystole

Dependent pooling of contrast in central veins, liver

Initiate cardiopulmonary resuscitation and page the code team