Quantification of blood velocity from time-resolved CT angiography on a 256-slice CT

Purpose: To quantify the blood velocity in the arteries of the lower extremities

and to investigate the correlation with peripheral arterial disease (PAD).

Methods and Materials: 7 Patients with suspicion of PAD underwent timeresolved

Computed Tomography Angiography (CTA) in addition to their

standard run-off CTA, consisting of 18 repeated axial acquisitions at 2s

interphase delay at the level of the calves with 16cm collimation (Revolution

CT, GE Healthcare). Image data was processed using in-house developed

processing tools. Motion during the acquisitions was compensated by applying

registration, after which the anterior tibial artery, posterior tibial artery and

peroneal artery were automatically segmented by identifying large intensity

changes over time. Subsequently, blood velocity was quantified in the arteries

by creating time attenuation curves (TAC) of the arterial cross-sections in every

slice and determining the time to peak (TTP).

Results: The described method led to plausible velocity estimations in all

arteries (n=18) for patients that were considered healthy (n=3). For

pathological patients (n=4), only 12 out of 22 arteries could be quantified due to

suboptimal bolus arrival, severe calcification or occlusions. For arteries of

healthy patients, blood velocity was normally distributed (p=0.282) with a

median value of 82.3 mm/s (95% CI= 55.5- 89.9 mm/s). Blood velocity in

arteries of pathological patients was observed to be significantly lower, 30.7

mm/s (95% CI= 27.4-45.7 mm/s), p<0.01.

Conclusion: Time-resolved CT data allows to quantify blood velocity in the

arteries of the lower extremities. In heavily occluded arteries, the contrast was

insufficient in order to quantify velocity.