Background The value of intravascular ultrasound (IVUS) imaging in patients with replacement of the ascending aorta for acute type A aortic dissection (AD) is unknown.The purpose of this study was to assess the potential use of IVUS imaging in this setting.Methods From September 2002 to July 2005,IVUS imaging with a 9 MHz probe was performed in a series of 16 consecutive patients with suspected or established AD.This study focused on 5 of them with replacement of the ascending aorta for acute type A AD.Among these 5 patients,other imaging modalities including aortography,spiral computed tomography,magnetic resonance imaging and transesophageal echocardiography were performed in 5,3,3 and 1 patients,respectively.Results There were no complications related to IVUS imaging.For the replaced graft,as other imaging modalities,IVUS could identify all 5 grafts,the proximal and the distal anastomoses,and the ostia of the reimplanted coronary arteries.In 2 cases,IVUS detected 2 peri-graft pseudo-aneurysms (1 per case),which were also detected by magnetic resonance imaging but omitted by aortography.For the residual dissection,IVUS had similar findings as other imaging modalities in detecting the patency (5/5),the longitudinal and the circumferential extent,the thrombus (4/5),the recurrent dissection (1/5) and an aneurysm distal to the graft (5 in 4 patients).However,it detected more intimal tears and side branch involvements than other imaging modalities (15 vs 10 and 3 vs 1,respectively).Conclusions In following-up patients with replacement of the ascending aorta for acute type A AD,IVUS imaging can provide complete information of the replaced graft and the residual dissection.So,IVUS imaging may be considered when the four current frequently used imaging modalities can not supply sufficient information or there are some discrepancies between them.