Low-dose CT with metal artifact reduction in arthroplasty imaging: a cadaveric and clinical study

Abstract

Objective To determine whether a simulated low-dose metal artifact reduction (MAR) CT technique is comparable with a clinical dose MAR technique for shoulder arthroplasty evaluation. Materials and methods Two shoulder arthroplasties in cadavers and 25 shoulder arthroplasties in patients were scanned using a clinical dose (140 kVp, 300 qrmAs); cadavers were also scanned at half dose (140 kVp, 150 qrmAs). Images were reconstructed using a MAR CT algorithm at full dose and a noise-insertion algorithm simulating 50% dose reduction. For the actual and simulated half-dose cadaver scans, differences in SD for regions of interest were assessed, and streak artifact near the arthroplasty was graded by 3 blinded readers. Simulated half-dose scans were compared with full-dose scans in patients by measuring differences in implant position and by comparing readers' grades of periprosthetic osteolysis and muscle atrophy. Results The mean difference in SD between actual and simulated half-dose methods was 2.42 HU (95% CI [1.4, 3.4]). No differences in streak artifact grades were seen in 13/18 (72.2%) comparisons in cadavers. In patients, differences in implant position measurements were within 1°or 1 mm in 149/150 (99.3%) measurements. The inter-reader agreement rates were nearly identical when readers were using full-dose (77.3% [232/300] for osteolysis and 76.9% [173/225] for muscle atrophy) and simulated half-dose (76.7% [920/1200] for osteolysis and 74.0% [666/900] for muscle atrophy) scans. Conclusion A simulated half-dose MAR CT technique is comparable both quantitatively and qualitatively with a standard-dose technique for shoulder arthroplasty evaluation, demonstrating that this technique could be used to reduce dose in arthroplasty imaging.

Validation of a 3D CT imaging method for quantifying implant migration following anatomic total shoulder arthroplasty

“…Lastly, our clinical CT‐based method requires radiation exposure higher than plain radiographs or marker‐based RSA methods; however, postoperative CT‐based assessment is becoming popular in clinical practice as it provides more accurate and reliable assessment of osteolysis around the implant and other qualitative and quantitative assessment, such as muscle atrophy and fatty infiltration following anatomic TSA. In the future, it may be possible to reduce the amount of radiation exposure to patients by using lower radiation doses, while still maintaining the quality and the accuracy of MAR 3D CT imaging, as demonstrated in the recently published study by Subhas et al 28 …”

“…All patients underwent the following sequential 3D CT scanning of the shoulder using the clinical patient imaging protocol as mentioned previously; 10,11,18 a preoperative CT, an immediate postoperative CT within 2 weeks of surgery (1-14 days), and a postoperative CT scan performed at minimum 2-year follow-up (763-839 days). In a published study 28 using the same CT imaging protocol in our clinic, the mean in-vivo effective dose for 25 patients was 12.6 ± 3.5 mSv (average ± SD), which is inconclusive to be considered as an increased risk of cancer or mortality according to the present official statement by the American Association of Physicists in Medicine (https://www.aapm. org/org/policies/details.asp?id=439%26type=PP%26current=true).…”