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High resolution peripheral quantitative computed tomography (HR-pQCT) is a 3-dimensional imaging modality with superior sensitivity for bone changes and abnormalities. Recent advances have led to increased use of HR-pQCT in inflammatory arthritis to report quantitative volumetric measures of bone density, microstructure, local anabolic (e.g., osteophytes, enthesiophytes) and catabolic (e.g., erosions) bone changes and joint space width. These features may be useful for monitoring disease progression, response to therapy, and are responsive to differentiating between those with inflammatory arthritis conditions and healthy controls. We reviewed 69 publications utilizing HR-pQCT imaging of the metacarpophalangeal (MCP) and/or wrist joints to investigate arthritis conditions. Erosions are a marker of early inflammatory arthritis progression, and recent work has focused on improvement and application of techniques to sensitively identify erosions, as well as quantifying erosion volume changes longitudinally using manual, semi-automated and automated methods. As a research tool, HR-pQCT may be used to detect treatment effects through changes in erosion volume in as little as 3 months. Studies with 1-year follow-up have demonstrated progression or repair of erosions depending on the treatment strategy applied. HR-pQCT presents several advantages. Combined with advances in image processing and image registration, individual changes can be monitored with high sensitivity and reliability. Thus, a major strength of HR-pQCT is its applicability in instances where subtle changes are anticipated, such as early erosive progression in the presence of subclinical inflammation. HR-pQCT imaging results could ultimately impact decision making to uptake aggressive treatment strategies and prevent progression of joint damage. There are several potential areas where HR-pQCT evaluation of inflammatory arthritis still requires development. As a highly sensitive imaging technique, one of the major challenges has been motion artifacts; motion compensation algorithms should be implemented for HR-pQCT. New research developments will improve the current disadvantages including, wider availability of scanners, the field of view, as well as the versatility for measuring tissues other than only bone. The challenge remains to disseminate these analysis approaches for broader clinical use and in research.

Purpose: Osteoarthritis (OA), rheumatoid arthritis (RA), and psoriatic arthritis (PsA) can all lead to the formation of bony proliferations (BP). This systematic review aimed to examine the characteristics of BPs in patients with RA, PsA, OA, and healthy controls (HC) using high‐resolution peripheral quantitative computed tomography (HR‐pQCT). Secondarily, we examined any treatment‐related effect on BP number and size. Methods: A systematic literature search was conducted in PubMed and Embase, and a total of 15 studies were included. Results: Seven studies demonstrated a disease‐specific variation in BP location. One study showed no difference in the number of BPs between patients with PsA and OA. The number of BPs was greater in patients with PsA compared to RA in one study, and to HC in another study, while one study documented no difference in the number of BPs between patients with RA and HC. Five studies showed larger BPs in patients with PsA compared to HC, and one study larger BPs in patients with PsA compared to RA. One study showed no difference in BP size between patients with PsA and OA. Secukinumab may have a potential effect on arresting BP progression. Otherwise, no other treatment was reported to influence BP size and progression. No standard definitions or measurement techniques for BPs using HR‐pQCT have been identified. Conclusion: BPs showed disease‐specific variations in location, size, and number. Results regarding treatment‐related effects are sparse. An agreement on the definition and measurement technique for BPs using HR‐pQCT is warranted for diagnostic accuracy, disease comparability, and monitoring potential. [ABSTRACT FROM AUTHOR]

Objectives: To compare if the 4th and 5th metatarsophalangeal (MTP) joints evaluated by high‐resolution peripheral quantitative computed tomography (HR‐pQCT) could classify more patients with erosive rheumatoid arthritis (RA) compared with conventional radiography (CR) of the hands, wrists, and feet. Furthermore, we characterize and quantify bone erosions in the two MTP joints by HR‐pQCT. Methods: This single‐center cross‐sectional study included patients with established RA (disease duration ≥5 years). Blinded to patient data, the number and volume of erosions in the 4th and 5th MTP joints were measured by HR‐pQCT, whereas the erosive scores by CR of 44 joints in the hands, wrists, and feet were assessed according to the Sharp/van der Heijde method. Results: Among 42 participants, 30 patients were classified with erosive RA and 12 with non‐erosive RA by CR. HR‐pQCT of two MTP joints could classify more patients with erosive RA compared with CR of 44 joints (p =.03). The optimal cut‐off value for the number and volume of erosions per patient in the 4th and 5th MTP joints by HR‐pQCT was 7.5 erosions and 11.7 mm3, respectively, for detecting erosive disease by CR. Erosions in the two MTP joints by HR‐pQCT were found most frequently and were largest at the lateral quadrant of the 5th metatarsal head. Conclusion: The superiority of HR‐pQCT of the 4th and 5th MTP joints compared with CR of 44 joints for classifying erosive RA provides a basis for larger studies evaluating if HR‐pQCT could be used for diagnosing erosive RA in the future. [ABSTRACT FROM AUTHOR]

Objective To investigate whether high-resolution peripheral quantitative CT (HR-pQCT) of two metacarpophalangeal (MCP) joints can more accurately classify patients as having erosive RA compared with conventional radiography (CR) of 44 joints in the hands, wrists and feet. Methods In this single-centre cross-sectional study, patients with established RA (disease duration ≥5 years) were investigated by HR-pQCT and CR. The second and third MCP joints of the dominant hand were assessed for erosions by HR-pQCT. CR of the hands, wrists and feet were scored according to the Sharp–van der Heijde (SHS) method. Results In total, 353 patients were included; 66 (18.7%) patients were classified as having non-erosive RA, and 287 (81.3%) had erosive RA by CR. The sensitivity and specificity (95% CI) of HR-pQCT for classifying patients as having erosive RA when standard CR of hands, wrists and feet was used as the reference was 89% (84, 92%) and 30% (20, 43%), respectively. Using HR-pQCT as the reference, the sensitivity and specificity of CR for classifying patients having erosive RA were 85% (80, 89%) and 38% (25, 52%), respectively. McNemar's χ2 test showed no significant difference between the sensitivities of patients classified as having erosive RA by HR-pQCT or by CR (2.14, P  = 0.177). Conclusion The diagnostic accuracy of HR-pQCT scanning of only two MCP joints and CR of 44 joints suggests the two modalities were comparable for classifying patients with established RA as having erosive disease. Clinical trial registration ClinicalTrials.gov (NCT03429426). [ABSTRACT FROM AUTHOR]

Aim: Bone erosions are the hallmark of rheumatoid arthritis (RA). High‐resolution peripheral quantitative computed tomography (HR‐pQCT) enables 3‐dimensional visualization of arthritic bone erosions at a high resolution. However, the degree of erosive disease could influence the reliability of HR‐pQCT evaluation. We aim to assess the intra‐ and inter‐reader variability of identification of erosions in the metacarpophalangeal (MCP) joints using HR‐pQCT in healthy controls and patients with RA, stratified according to van der Heijde‐modified Sharp Score (HSS) of radiographic erosions. Method: We analyzed HR‐pQCT images from 78 patients with RA and 25 healthy controls. Patients were allocated to one of three groups of mild, moderate or severe disease according to HSS of MCP joints 2 and 3. Total HR‐pQCT scans were analyzed twice in random order by three experienced readers, blinded to group distribution. The number of cortical interruptions and their classification as either erosions or cysts according to predefined criteria were recorded. Intraclass correlation coefficients (ICC) for cortical interruptions, erosions and cysts were calculated for each group using a 2‐way random‐effects model for inter‐reader ICC and a 2‐way mixed‐effects model for intra‐reader ICC. Results: The intra‐ and inter‐reader ICC were good to moderate for cortical interruptions and moderate for erosions throughout disease severity groups. The ICCs for the identification of cysts decreased with increasing degree of erosive disease. Conclusion: The detection of cortical interruptions is only minimally affected by the degree of erosive damage, whereas the distinction between erosions and cysts is more complex in patients with extensive erosive disease. [ABSTRACT FROM AUTHOR]

Objectives The diagnostic accuracy of axillary artery US in the diagnosis of large-vessel (LV)-GCA using 18F-fluorodeoxyglucose (FDG) PET/CT as reference standard was prospectively evaluated in GCA-suspected patients. As an exploratory analysis, the diagnostic accuracy of cranial artery FDG PET/CT was evaluated. Methods Briefly, the inclusion criteria were age ≥50 years, raised inflammatory markers and potential GCA symptoms. Patients in immunosuppressive therapy or with a previous diagnosis of GCA or PMR were excluded. Examinations were performed pre-treatment. LV-GCA reference diagnosis was a clinical diagnosis of GCA and PET-proven LV inflammation. GCA patients fulfilling ACR criteria were considered as cranial-GCA (c-GCA). Patients without GCA were considered controls. Receiver operating characteristic curve analysis of the US-measured axillary intima-media thickness was performed. FDG uptake in temporal, maxillary and vertebral arteries was also assessed. Results Forty-six patients were diagnosed with LV-GCA, 10 with isolated c-GCA, and in 34 patients GCA was dismissed. Axillary US yielded a sensitivity of 76% and a specificity of 100% for LV-GCA. An axillary intima-media thickness cut-off of 1.0 mm yielded a sensitivity of 74% and a specificity of 92%. Adding LV US to temporal assessment increased sensitivity from 71% to 97% (all GCA patients). Cranial artery PET showed a diagnostic sensitivity of 78% and specificity of 100% for c-GCA. Conclusion Axillary artery US shows high accuracy for the LV-GCA diagnosis. Building upon the recent EULAR recommendations, we propose a diagnostic algorithm with US as the first-line confirmatory test, not only in c-GCA-suspected patients, but in all patients suspected of GCA. [ABSTRACT FROM AUTHOR]

Purpose: To estimate the diagnostic accuracy of conventional 18F-FDG PET/CT of cranial arteries in the diagnosis of giant cell arteritis (GCA).Methods: The study was a retrospective case-control study. The reference diagnosis was fulfillment of the 1990 ACR criteria for GCA. All patients had new-onset GCA. Conventional 18F-FDG PET/CT was performed before glucocorticoid treatment. Controls were age- and sex-matched patients with a previous history of malignant melanoma (MM) undergoing surveillance PET/CT >6 months after MM resection. PET images were evenly cropped to include only head and neck and were assessed in random order by four nuclear medicine physicians blinded to reference diagnosis. Temporal (TA), maxillary (MA) and vertebral (VA) arteries were visually rated for 18F-FDG uptake. Interreader agreement was evaluated by Fleiss kappa.Results: A total of 44 patients and 44 controls were identified. In both groups, the mean age was 69 years (p = 0.45) and 25/44 were women. 35/41 GCA patients were temporal artery biopsy positive (TAB). Considering only FDG uptake in TA and/or MA, diagnostic sensitivity and specificity was 64 and 100%. Including VA, sensitivity increased to 82% and specificity remained 100%. Interreader agreement was 91% and Fleiss kappa 0.82 for the PET diagnosis based on the cranial arteries.Conclusion: Conventional 18F-FDG PET/CT is an accurate and reliable tool to diagnose cranial arteritis in glucocorticoid-naïve GCA patients. The high diagnostic specificity suggests that TAB can be omitted in patients with 18F-FDG uptake in cranial arteries. 18F-FDG PET/CT performed in patients with suspected vasculitis should always include the head and neck. [ABSTRACT FROM AUTHOR]