Optimal scanning timing by use of multi-detector row computed tomography during thoracic aortography for depiction of arteries causing hemoptysis.

Scanning timing for multi-detector row computed tomography during thoracic aortography (MDCT-TA) was explored for depiction of arteries responsible for hemoptysis. The mean time (MT) from contrast medium (CM) injection to peak enhancement (PE) in the descending aorta at the level of the diaphragm on thoracic aortography was investigated. The MT to PE of the descending aorta at the level of diaphragm was 4.86 ± 0.42 s, with 30 mL CM at an injection rate of 10 mL/s. CM injection was completed 1.86 s before the final slice was obtained. The CM injection duration can be calculated as follows: 4.86 s + scan time - 1.86 s. The optimal scanning timing is a scan delay of approximately 5 s from the start of CM injection, and the CM injection duration is expressed as scan time plus 3 s. MDCT-TA depicted the branching sites of the bronchial arteries in all cases.