Open AccessDual-energy computed-tomography-based discrimination between basic calcium phosphate and calcium pyrophosphate crystal deposition in vivo
Author(s) -
Tristan Pascart,
Guillaume Falgayrac,
Laurène Norberciak,
Clément Lalanne,
Julie Legrand,
É. Houvenagel,
HangKorng Ea,
Fabio Becce,
Jean-François Budzik
Publication year - 2020
Publication title -
therapeutic advances in musculoskeletal disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.387
H-Index - 35
eISSN - 1759-7218
pISSN - 1759-720X
DOI - 10.1177/1759720x20936060
Subject(s) - effective atomic number , digital enhanced cordless telecommunications , calcium pyrophosphate , calcium , in vivo , nuclear medicine , medicine , crystal (programming language) , calcification , attenuation , radiology , optics , physics , telecommunications , programming language , microbiology and biotechnology , computer science , wireless , biology
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 ( Z eff ). 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 Z eff .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/cm 3 : 0.037 ± 0 versus 0.034 ± 0, p = 0.008) and Z eff (200 mg /cm 3 : 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 Z eff (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.