하지 64 MDCT 혈관조영술에서 outrun 예방을 위한 검사방법

The Methods of Prevention to Outrun in lower extremity 64 MDCT Angiography

Purpose In present, MDCT has come into wide use. But outrun often occurs due to fast scanning and rotation time in lower extremity CT angiography with-64 MDCT. We studied the prevention to outrun in lower extremity CT angiography. Materials and Methods Between October 2006 and January 2007, during a period of 4 months, total 210 patients underwent a lower extremity CT angiography with 64 channel MDCT. We scanned patients from the level of lumber-spine three to feet in a single helical scan with 64 MDCT. Examination was scanned by each of different scanning methods. We changed the scan parameter in 3 ways. First, we set the delay time to 6.4 sec and the rotation time to 1sec. We called it to PG 1 (aorta slow). Second, we set the delay time to 20 sec and the rotation time to 0.4 sec. We called it PG 2 (aorta fast). Third method was same as PG 1 except of setting triggering level to popliteal artery. It was called for PG 3 (popliteal fast). The data from scanning was transmitted to 3D software program. Three-dimensional images were obtained using MIP(maximum intensity projection). Four radiologist evaluated all the results in reference to outrun, vein contamination, motion artifact and enhancement of vessel. Results In PG 1, there was no outrun. But it had some vein contamination and motion artifact because of long scan time. In PG 2, there was some outrun. But it had hardly vein contamination and motion artifact due to fast scan time. In PG 3, there was no outrun, too On the a:her hand, it had some vein contamination. Conclusion The best way to prevent outrun is program one (PG 1) or program three (PG 3) in lower extremity CT angiography with 64 MDCT. But each method has inherently a merit and demerit. We should use the protocol which is fit to patient history.