A comparative study of tomosynthesis, computed tomography and X-ray in imaging the structures around hip prostheses

MA Yi-min; SU Yong-bin; SHAO Hong-yi; WANG Chen; XU Li; LI Na; ZHOU Yi-xin; CHENG Xiao-guang

doi:10.3969/j.issn.2095-252X.2014.11.07

Abstract：Objective To compare the capacity of tomosynthesis ( TOMOS ), computed tomography ( CT ) and digital radiography ( DR ) in imaging hip prostheses and their surrounding structures.Methods A total of 20 consecutive patients receiving either unilateral or bilateral total hip arthroplasty ( THA ) were enrolled, including 12 males and 8 females. Their mean age was 61.0 years old ( range: 36-82 years ). All the patients underwent TOMOS, CT and DR after THA. The TOMOS, CT and DR images of the 20 patients were reviewed and subjectively scored by 3 senior attending radiologists. The evaluation standard was stated as following. The clear image of the structures around the prostheses was rated as “excellent”, with the score of 2 points. The sharpness of the image was affected by minor artifacts or lower resolution, but the basic observation wasn’t affected. Such images were rated as “mid”, with the score of 1 point. If the image deifnition was seriously affected by metal artifacts or other factors, it was rated as “poor”, with the score of 0 point. The scores calculated would be statistically analysed via Generalized Estimating Equations.Results The score frequency distribution of TOMOS imaging for the acetabulum ( including the hip joint space ) was 55% ( 2 points ), 40% ( 1 point ), and 5% ( 0 point ). The score frequency distribution of TOMOS imaging for the proximal femoral peri-prothesis region was 75% ( 2 points ), 25% ( 1 point ), and 0% ( 0 point ). The score frequency distribution of CT imaging for the acetabulum ( including the hip joint space ) is 5% ( 2 points ), 60%( 1 point ), and 35% ( 0 point ). The score frequency distribution of CT imaging for the proximal femoral peri-prothesis region was 5% ( 2 points ), 55% ( 1 point ), and 40% ( 0 point ). TOMOS was superior to CT in image quality, and the differences in the scores were statistically signigicant (P<0.001 ). The score frequency distribution of DR imaging for the acetabulum ( including the hip joint space ) was 25% ( 2 points ), 75% ( 1 point ), and 0% ( 0 point ). The score frequency distribution of DR imaging for the proximal femoral peri-prothesis region was 50% ( 2 points ), 50%( 1 point ), and 0% ( 0 point ). The image deifnition of DR was better than that of CT, and the differences in the scores were statistically signigicant (P=0-0.0077 ).Conclusions The TOMOS imaging quality of hip prostheses is better than that of CT, with the advantage of layering and thin-slice observation over DR. Thus, TOMOS is a promising imaging modality in the follow-up after THA .