Scan-timed CT angiography in experimental arthritis: selective placement of regions of interest.

Scan-timed computed tomography (CT) angiography is a functional imaging technique that evaluates the perfusion kinetics of tissue using time-attenuation curves derived from dynamic CT acquisition. While water shifts do not affect CT, which is an advantage of this technique over MR imaging, CT angiography tends to be less sensitive to contrast media than MR imaging. We conducted a pilot study to evaluate the ability of scan-timed CT angiography to differentiate maximum enhancement values according to the inflammatory status of rabbit joints using different regions of interest for analysis of the data. Four animals had arthritis in one of their knees and four animals served as controls.