Dual energy computed tomography cannot effectively differentiate between calcium pyrophosphate and basic calcium phosphate diseases in the clinical setting

Mohamed Jarraya; Olivier Bitoun; Dufan Wu; Rene Balza; Ali Guermazi; Jamie Collins; Rajiv Gupta; Gunnlaugur Petur Nielsen; Elias Guermazi; F Joseph Simeone; Patrick Omoumi; Christopher M Melnic; Seonghwan Yee

doi:10.1016/j.ocarto.2024.100436

Dual energy computed tomography cannot effectively differentiate between calcium pyrophosphate and basic calcium phosphate diseases in the clinical setting

Osteoarthr Cartil Open. 2024 Jan 24;6(1):100436. doi: 10.1016/j.ocarto.2024.100436. eCollection 2024 Mar.

Authors

Affiliations

¹ Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
² VA Boston Healthcare, Boston University School of Medicine, Boston, MA, USA.
³ Orthopedic and Arthritis Center for Outcomes Research, Department of Orthopedic Surgery, Brigham and Women's Hospital, USA.
⁴ Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
⁵ Boston University, Boston, MA, USA.
⁶ Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
⁷ Department of Orthopedics, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.

Abstract

Background: Recent reports suggested that dual-energy CT (DECT) may help discriminate between different types of calcium phosphate crystals in vivo, which would have important implications for the characterization of crystal deposition occurring in osteoarthritis.

Purpose: Our aim was to test the hypothesis that DECT can effectively differentiate basic calcium phosphate (BCP) from calcium pyrophosphate (CPP) deposition diseases.

Methods: Discarded tissue after total knee replacement specimens in a 71 year-old patient with knee osteoarthritis and chondrocalcinosis was scanned using DECT at standard clinical parameters. Specimens were then examined on light microscopy which revealed CPP deposition in 4 specimens (medial femoral condyle, lateral tibial plateau and both menisci) without BCP deposition. Regions of interest were placed on post-processed CT images using Rho/Z maps (Syngo.via, Siemens Healthineers, VB10B) in different areas of CPP deposition, trabecular bone BCP (T-BCP) and subchondral bone plate BCP (C-BCP).

Results: Dual Energy Index (DEI) of CPP was 0.12 (SD = 0.02) for reader 1 and 0.09 (SD = 0.03) for reader 2, The effective atomic number (Z_eff) of CPP was 10.83 (SD = 0.44) for reader 1 and 10.11 (SD = 0.66) for reader 2. Nearly all DECT parameters of CPP were higher than those of T-BCP, lower than those of C-BCP, and largely overlapping with Aggregate-BCP (aggregate of T-BCP and C-BCP).

Conclusion: Differentiation of different types of calcium crystals using DECT is not feasible in a clinical setting.

Keywords: CT; Calcium phosphate; Crystal; Dual energy; Osteoarthritis.