Using Dual-Energy CT for Painful Hip Arthroplasties
2021; Radiological Society of North America; Volume: 300; Issue: 3 Linguagem: Inglês
10.1148/radiol.2021211272
ISSN1527-1315
Autores Tópico(s)Radiation Dose and Imaging
ResumoHomeRadiologyVol. 300, No. 3 PreviousNext Reviews and CommentaryFree AccessEditorialUsing Dual-Energy CT for Painful Hip ArthroplastiesAmelie M. Lutz Amelie M. Lutz Author AffiliationsFrom the Division of Musculoskeletal Imaging, Department of Radiology, Stanford University School of Medicine, 354 Quarry Rd, Palo Alto, CA 94304.Address correspondence to the author (e-mail: [email protected]).Amelie M. Lutz Published Online:Jul 6 2021https://doi.org/10.1148/radiol.2021211272MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In See also the article by Foti et al in this issue.Amelie M. Lutz, MD, associate professor of radiology and co-division chief of musculoskeletal imaging at Stanford School of Medicine, is an NIH-funded physician-scientist with interests in peripheral nerve imaging and molecular US imaging in oncology. After medical school and doctoral thesis in virology at the University Freiburg, Germany; residency training at the University of Zurich and Kantonsspital Frauenfeld, Switzerland; and molecular imaging post-doctoral fellowship at Stanford, she joined the Stanford faculty in 2011.Download as PowerPointOpen in Image Viewer The painful arthroplasty is a nightmare foremost for patients but also for the treating surgeons. Patients frequently suffer years of pain leading to the often-difficult decision to undergo joint replacement with the promise of painless mobility. The last scenario patients expect is a continued ordeal with pain after arthroplasty and the associated diagnostic dilemma. The treating surgeons do not want to revise an arthroplasty unless it is absolutely necessary and they are certain about the underlying cause of the pain. With more than 1 million hip replacements performed worldwide annually, continued pain after hip replacement surgery is not necessarily a rare event. In the literature, persistent pain for more than 6–18 months after surgery is reported in 6%–12% of patients, with persistent discomfort in an impressive 27% (1,2).The causes behind painful arthroplasties are quite heterogeneous and range from infection to soft-tissue or nerve damage, stress changes in the adjacent bone, hardware failure, and aseptic loosening. Of course, in the hip, there are multiple other potential pain confounders: not only periarticular pain from trochanteric bursitis or gluteal and iliopsoas tendonitis but also often referred pain from knee osteoarthritis and back issues (3). Obviously, entities such as infection or periprosthetic fractures have to be ruled out first, but once they are, narrowing down the exact cause becomes more challenging. In painful hip prostheses, prosthesis loosening is one of the most important and also most difficult entities to diagnose. As radiologists, we adhere to the rule of greater than or equal to 2 mm smooth osseous lucency surrounding prosthesis components as a sign of implant loosening on radiographs. Traditionally, reported sensitivity and specificity values of radiography in prosthesis loosening were around 80% (4). But a recent study (5) suggests that the sensitivity of radiography in the diagnosis of implant loosening may be much lower: 20%–26% compared with the sensitivities and specificities of 75%–83% and 98%–100%, respectively, for MRI.At our institution, with a very busy academic orthopedic reference center, we receive referrals for the diagnostic imaging work-up of painful hip arthroplasties in many patients, usually several per week. These patients often come to our institution for second opinions after undergoing surgery at other facilities. Apart from performing radiography and hip aspirations to rule out infections, we usually perform metal artifact–reducing sequence MRI, one of the specialties of our division. The usual suspect entities include adverse soft-tissue reactions, tendon abnormalities, and, of course, implant loosening. But despite the great advancements in metal artifact–reducing sequence MRI, the promising results in publications, and the favorable lack of ionizing radiation (5), image quality and findings are not always perfectly straightforward in the routine clinical setting. The differentiation between signal artifact near metal and true loosening of an implant requires an experienced reader and good scan quality. Also, the MRI examination duration can be challenging for patients experiencing severe pain.In this issue of Radiology, Foti et al (6) present a viable tool in the diagnostic work-up of painful hip arthroplasty: dual-energy CT (DECT) to rule out implant loosening. DECT is tremendously valuable in many settings, including musculoskeletal imaging. The metal artifact–reducing capabilities of DECT in the postsurgical setting with hardware in place are known to be especially helpful in the postoperative spine (7). DECT uses two x-ray tubes producing different kilovoltage peaks offset at approximately 90°, offering the capability for virtual monoenergetic reconstructions at high kilovoltage peaks. Several recent publications have shown these virtual monoenergetic reconstructions, either alone or in combination with iterative reconstruction, to improve the image quality by substantially reducing metal artifacts in the periprosthetic bone and soft tissues.In their retrospective single-center study, Foti and colleagues evaluated 178 patients. Surgery as the reference standard was performed in 121 patients, while a 1-year follow-up was used to rule out implant loosening in 57 patients who did not undergo surgery. At surgery, implant loosening was found in close to 50% of patients (87 of 178), most frequently along the femoral stem component, followed by the acetabular component and loosening of both components. The two readers based their diagnosis of prothesis loosening on the presence of a direct sign of loosening (periprosthetic lucency ≥2 mm in width) or on the presence of two or more indirect findings on DECT scans. Those indirect signs included periprosthetic osteolysis (focal areas of bone reabsorption or asymmetric areas of reduced bone conspicuity near the implant), abnormal angulation or dislocation of the femoral stem, abnormally increased acetabular inclination angle, and any fracture or abnormal periosteal reaction adjacent to the implant. The two readers correctly diagnosed more loosened prostheses at DECT than at radiography, with sensitivity and specificity both over 90% for DECT versus sensitivity and specificity of 82% and less than 90%, respectively, for radiography. The interobserver agreement was near-perfect for DECT, and the agreement was good for radiography. The presence of the primary sign of a periprosthetic gap turned out to be more helpful in the diagnosis of loosening than a combination of secondary signs of loosening. As noted by the authors, in the rare absence of a periprosthetic gap and of secondary signs, the diagnosis may remain difficult even with DECT.Obviously, radiography as a first step in the diagnostic work-up of painful hip arthroplasties and potential loosening will not be replaced by DECT. The method is simply too expensive and not as ubiquitously available as radiography, although many of the centers that routinely deal with complex revision of hip arthroplasties would likely have these scanners available. Overall, the authors present a diagnostic tool with the potential of becoming a problem solver in the diagnostics of aseptic arthroplasty loosening.Interestingly, our second most common referral reason to rule out prosthesis loosening is pain after shoulder replacement. Currently, we deal with that diagnostic dilemma with CT arthrograms. This allows reliable detection of loosening, characterized by invasion of contrast material along the bone cement interface. So, it would be very helpful to systematically study and define the value of DECT in other arthroplasty types as well.Disclosures of Conflicts of Interest: A.M.L. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: institution received or will receive grants from the National Institutes of Health; institution received research funding for MR neurography efforts from GE Healthcare; institution received research material support from Bracco Diagnostics. Other relationships: disclosed no relevant relationships.References1. Nikolajsen L, Brandsborg B, Lucht U, Jensen TS, Kehlet H. Chronic pain following total hip arthroplasty: a nationwide questionnaire study. Acta Anaesthesiol Scand 2006;50(4):495–500. Crossref, Medline, Google Scholar2. Lanting BA, MacDonald SJ. The painful total hip replacement: diagnosis and deliverance. Bone Joint J 2013;95-B(11 Suppl A):70–73. Crossref, Medline, Google Scholar3. Erivan R, Villatte G, Ollivier M, Paprosky WG. Painful hip arthroplasty: what should we find? Diagnostic approach and results. J Arthroplasty 2019;34(8):1802–1807. Crossref, Medline, Google Scholar4. Temmerman OP, Raijmakers PG, Berkhof J, Hoekstra OS, Teule GJ, Heyligers IC. Accuracy of diagnostic imaging techniques in the diagnosis of aseptic loosening of the femoral component of a hip prosthesis: a meta-analysis. J Bone Joint Surg Br 2005;87(6):781–785. Crossref, Medline, Google Scholar5. Burge AJ, Konin GP, Berkowitz JL, Lin B, Koff MF, Potter HG. What is the diagnostic accuracy of MRI for component loosening in THA? Clin Orthop Relat Res 2019;477(9):2085–2094. Crossref, Medline, Google Scholar6. Foti G, Fighera A, Campacci A, et al. Diagnostic performance of dual-energy CT for detecting painful hip prosthesis loosening. Radiology 2021. https://doi.org/10.1148/radiol.2021203510. Published online July 6, 2021. Google Scholar7. McCollough CH, Leng S, Yu L, Fletcher JG. Dual- and multi-energy CT: principles, technical approaches, and clinical applications. Radiology 2015;276(3):637–653. Link, Google ScholarArticle HistoryReceived: May 17 2021Revision requested: May 24 2021Revision received: June 14 2021Accepted: June 16 2021Published online: July 06 2021Published in print: Sept 2021 FiguresReferencesRelatedDetailsAccompanying This ArticleDiagnostic Performance of Dual-Energy CT for Detecting Painful Hip Prosthesis LooseningJul 6 2021RadiologyRecommended Articles Dual-Energy CT for Detecting Painful Knee Prosthesis LooseningRadiology2022Volume: 306Issue: 3Diagnostic Performance of Dual-Energy CT for Detecting Painful Hip Prosthesis LooseningRadiology2021Volume: 300Issue: 3pp. 641-649Periprosthetic Femoral Fractures in the Emergency Department: What the Orthopedic Surgeon Wants to KnowRadioGraphics2017Volume: 37Issue: 4pp. 1202-1217Metal Artifact Reduction MRI in the Diagnosis of Periprosthetic Hip Joint InfectionRadiology2022Volume: 306Issue: 3Current and Novel Techniques for Metal Artifact Reduction at CT: Practical Guide for RadiologistsRadioGraphics2018Volume: 38Issue: 2pp. 450-461See More RSNA Education Exhibits A Pictorial Review Of Peri Prosthetic Fractures In Hip And Knee Replacement: A Radiologist's Guide To Key Clues In Reporting.Digital Posters2021A Radiological Overview of Hip Arthroplasty: Practical Keys in the Assessment of Hip ReplacementDigital Posters2019Elusive Complications in Hip Arthroplasty - Dare to Spot It: Imaging Features of Uncommon Postoperative ComplicationsDigital Posters2019 RSNA Case Collection Metallosis after right hip replacementRSNA Case Collection2020Hip Polyethylene Liner DissociationRSNA Case Collection2021Subcapital Femoral Neck FractureRSNA Case Collection2021 Vol. 300, No. 3 Metrics Altmetric Score PDF download
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