High-resolution peripheral quantitative CT in rheumatology

Abstract

CORRESPONDENCEWe read with interest the Perspectives article by Filippucci et al. (Progress in imaging in rheumatology. Nat. Rev. Rheumatol. 10, 628-634;. 1 This article is a very informative concise paper on MRI and musculoskeletal ultrasono graphy. However, we were surprised that no mention was made of high-resolution peripheral quantitative CT (HR-pQCT), previously highlighted in a Review in this journal, 2 and we would like to call attention to its emerging potential in the field of advanced diagnostic imaging.HR-pQCT was initially developed to study bone diseases such as osteoporosis, and has contributed to a better understanding of the separate behavior of trabecular and cortical bone structures and the different cortical envelopes during ageing, in metabolic bone diseases and during fracture healing; 2 moreover, it allows for calculation of bone strength in vivo using finite-element analysis. 3 Due to its ability to evaluate bone in 3D at a high resolution (82 μm) and with minimal irradiation (5 μSv to image a 0.9 cm region of interest), HR-pQCT is being intensely investigated in the evaluation of bone architecture in the small joints of the hands in rheumatoid arthritis, 4-6 psori atic arthritis, 7 and hand osteoarthritis. 8 To what degree can this method now be rated as "progress in imaging" in rheumatology?Firstly, an increased number of, and earlier stages of, erosions are visible with HR-pQCT than on plain radiography, as evidenced by the work of Stach et al. 4 Secondly, quantification of erosions in terms of size (width, depth and volume) together with changes in trabecular bone is possible, and has been studied in crosssectional and longitudinal studies 5,9-11 and in comparison with MRI. 6 Thirdly, a 3D assessment of joint space is described using quantitative analysis algorithms. 12,13 Fourthly, 3D measurement of bone microarchitecture in rheumatoid arthritis patients showed altered results with disease High-resolution peripheral quantitative CT in rheumatologyCheryl Barnabe, Stephanie Finzel, Kathryn S. Stok and Piet Geusens activity. 14 None of these 3D parameters can currently be evaluated by other imaging techniques at such high resolution.In conclusion, HR-pQCT is, besides MRI and musculoskeletal ultrasonography, also promising "progress in imaging" for clinical research in rheumatic disease of the hand joints. SPECTRA (Study Group for X-treme CT in Rheumatoid Arthritis) 15 is an inter national collaboration between rheumatologists, radiologists, biomedical engineers, physicists and clinical researchers in bone metabolism and osteoimmunology that has provided fertile ground for crossdisciplinary research, united by the desire to certify the validity of the research findings from the application of this technology to the assessment of inflammatory arthritis.

HR-pQCT has promise in rheumatology

“…Nevertheless, we agree with Barnabe et al 2 in believing that HR-pQCT can be considered one of the most promising imaging modalities, which will see researchers of different specialties working together to further clarify its use in patients with bone disorders and inflammatory arthritis. …”

“…doi:10.1038/nrrheum.2014.145-c1). 2 Their letter highlights the potential of high-resolution peripheral quantitative CT (HR-pQCT). This is really an emerging imaging technique which provides an in vivo assessment in patients with bone and joint diseases, opening a new dimension in the study of the bony microarchitecture.…”

Assessment of 3-month changes in bone microstructure under anti-TNFα therapy in patients with rheumatoid arthritis using high-resolution peripheral quantitative computed tomography (HR-pQCT)

“…High-resolution peripheral quantitative computed tomography (HR-pQCT), is a very sensitive imaging tool to detect bone erosions [ 10 ] and to evaluate cortical and trabecular bone mineral density (BMD) and microstructure in RA [ 11 ]. It has also been applied in studies of psoriatic arthritis [ 12 ] and hand osteoarthritis [ 13 ].…”

Age- and Sex-Dependent Changes of Intra-articular Cortical and Trabecular Bone Structure and the Effects of Rheumatoid Arthritis

“…In contrast, high‐resolution peripheral quantitative computed tomography (HR‐pQCT) allows exact quantification of trabecular and cortical bone in the human radius and tibia . During the last years, HR‐pQCT has been introduced to characterize bone erosions and systemic bone loss in patients with RA and other forms of arthritis …”