The study of Nguyen Thi Anh Dao (2012) was similar with results of PVT in the trunk or PVT in both branch and trunk (grade Vp4) of 42.8% for ultrasound and 60.3% for CT scan, PVT in only branch (Vp2 and Vp3) of 32.3% for ultrasound and 33.3% for CT scan.