Objective: To determine the dual-energy computed tomography (DECT) attenuation properties of meniscal calcifications in calcium pyrophosphate deposition (CPPD) in vivo, and assess whether DECT was able to discriminate meniscal CPP deposits from calcium hydroxyapatite (HA) in subchondral and trabecular bone. Method: Patients with clinical suspicion of crystal-related arthropathy (gout and/or CPPD) and knee DECT scans were retrospectively assigned to CPPD (n ¼ 19) or control (n ¼ 21) groups depending on the presence/absence of chondrocalcinosis on DECT. Two observers drew standardized regions of interest (ROI) in meniscal calcifications, non-calcified menisci, as well as subchondral and trabecular bone. Five DECT parameters were obtained: CT numbers (HU) at 80 and 140 kV, dual-energy index (DEI), electron density (r e), and effective atomic number (Z eff). The four different knee structures were compared within/between patients and controls using linear mixed models, adjusting for confounders. Results: Meniscal calcifications (n ¼ 89) in CPPD patients had mean ± SD CT numbers at 80 and 140 kV of 257 ± 64 and 201 ± 48 HU, respectively; with a DEI of 0.023 ± 0.007, and r e and Z eff of 140 ± 35 and 8.8 ± 0.3, respectively. Meniscal CPP deposits were readily distinguished from calcium HA in subchondral and trabecular bone (p 0.001), except at 80 kV separately (p ¼ 0.74). Z eff and r e both significantly differed between CPP deposits and calcium HA in subchondral and trabecular bone (p < 0.0001). Conclusion: This proof-of-concept study shows that DECT has the potential to discriminate meniscal CPP deposits from calcium HA in subchondral and trabecular bone in vivo, paving the way for the noninvasive biochemical signature assessment of intra-and juxta-articular calcium crystal deposits.
Choosing the subcutaneous (SC) route of administration of abatacept and tocilizumab is more cost-effective than the intravenous (IV) route. The objective of this study was to examine patients' reasons for choosing to keep with their IV infusions or to switch to subcutaneous SC injections. This study was based upon a self-administered questionnaire given to consecutive rheumatoid arthritis patients treated with abatacept or tocilizumab. Patients were asked to express their opinions concerning reasons explaining why they chose to keep the IV route or switch to the SC route. A total of 201 questionnaires completed by 127 patients treated by tocilizumab and 74 by abatacept were analysed. Overall, 45.8% of the patients chose to keep the IV route of administration. Another ongoing SC treatment was noted more often in patients choosing the SC route (15.9 versus 4.3%, p < 0.05). Reasons guiding the choice of the SC route were concerns about repeated hospital day-care (72%), greater autonomy with SC injections (38.7%) and economic considerations (21.5%). Reasons associated with choosing to maintain the IV route were worries about a lack of follow-up (72.1%), the absence of medical assistance during the SC injection (61.2%), maintaining social relationships with other patients developed at the hospital (40.5%), lower frequency of injection (32.9%), fear of adverse events (27.7%) and fear of SC injections (17.9%). Patients reject the SC switch from the IV route of tocilizumab and abatacept mainly because of fears about the unknown SC route, while those who accept it find it more convenient.
Background: Dual-energy computed tomography (DECT) is being considered as a non-invasive diagnostic and characterization tool in calcium crystal-associated arthropathies. Our objective was to assess the potential of DECT in distinguishing between basic calcium phosphate (BCP) and calcium pyrophosphate (CPP) crystal deposition in and around joints in vivo. Methods: A total of 13 patients with calcific periarthritis and 11 patients with crystal-proven CPPD were recruited prospectively to undergo DECT scans. Samples harvested from BCP and CPP calcification types were analyzed using Raman spectroscopy and validated against synthetic crystals. Regions of interest were placed in BCP and CPP calcifications, and the following DECT attenuation parameters were obtained: CT numbers (HU) at 80 and 140 kV, dual-energy index (DEI), electron density (Rho), and effective atomic number ( Zeff). These DECT attenuation parameters were compared and validated against crystal calibration phantoms at two known equal concentrations. Receiver operating characteristic (ROC) curves were plotted to determine the highest accuracy thresholds for DEI and Zeff. Results: Raman spectroscopy enabled chemical fingerprinting of BCP and CPP crystals both in vitro and in vivo. DECT was able to distinguish between HA and CPP in crystal calibration phantoms at two known equal concentrations, most notably by DEI (200 mg/cm3: 0.037 ± 0 versus 0.034 ± 0, p = 0.008) and Zeff (200 mg /cm3: 9.4 ± 0 versus 9.3 ± 0, p = 0.01) analysis. Likewise, BCP calcifications had significantly higher DEI (0.041 ± 0.005 versus 0.034 ± 0.005, p = 0.008) and Zeff (9.5 ± 0.2 versus 9.3 ± 0.2, p = 0.03) than CPP crystal deposits with comparable CT numbers in patients. With an area under the ROC curve of 0.83 [best threshold value = 0.0 39, sensitivity = 90. 9% (81.8, 97. 7%), specificity = 64.6% (50.0, 64. 6%)], DEI was the best parameter in distinguishing between BCP and CPP crystal depositions. Conclusion: DECT can help distinguish between crystal-proven BCP and CPP calcification types in vivo and, thus, aid in the diagnosis of challenging clinical cases, and in the characterization of CPP and BCP crystal deposition occurring in osteoarthritis.
Non-traumatic osteonecrosis (ON) of the femoral head is a common disease affecting a young population as the peak age of diagnosis is in the 40 s. The natural history of non-traumatic ON leads to a collapse of the femoral head requiring prosthetic replacement in a 60% of cases. Although trabecular bone involvement in the collapse is suspected, the underlying modifications induced at a molecular level have not been explored in humans. Here, we examine changes in the molecular composition and structure of bone as evaluated by Raman spectroscopy in human end-stage ON. Comparing samples from femoral heads harvested from 11 patients and 11 cadaveric controls, we show that the mineral and organic chemical composition of trabecular bone in ON is not modified apart from age-related differences. We also show that the molecular composition in the necrotic part of the femoral head is not different from the composition of the remaining ‘healthy’ trabecular bone of the femoral head. These findings support that quality of trabecular bone is not modified during ON despite extensive bone marrow necrosis and osteocyte death observed even in the ‘healthy’ zones on histological examination.
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