Raman hyperspectral imaging detects novel and combinations of crystals in synovial fluids of patients with a swollen joint

Abstract

The identification of synovial crystals is important for diagnosing rheumatic diseases. Currently, rheumatologists worldwide use compensated polarized light microscopy (CPLM) for crystal identification, but this technique is flawed. Raman spectroscopy might offer an objective, accurate alternative. We have tested Raman hyperspectral imaging on synovial fluid samples of 28 patients with swollen joints, measuring 5–10 crystals in each of these. Reference spectra for identification were measured using patient material, synthetic compounds, and oxalate kidney stones. Additionally, RRUFF and PANGAEA Raman databases were used to identify spectra. We identified the classical pathological crystals monosodium urate for gout and calcium pyrophosphate for calcium pyrophosphate deposition disease (CPPD). Hydroxyapatite, lipid spherules, and calcium oxalate monohydrate have also been observed and had been previously identified in synovial fluids. Other crystals, which were not previously observed in synovial fluid using CPLM, have been identified as well: calcite, aragonite, anatase, rutile, thenardite, dolomite, and a carotenoid. In addition, we found combinations of crystals in 13 out of 28 patients. We propose that the observed large variation of detectable crystals from a small population of patients and a small number of crystals per patient has significant ramifications for the use of compensated polarized light microscopy for the diagnosis of gout and CPPD. Further studies are required to learn the clinical significance of these crystals in human arthritis.

The Prevalence of Titanium Dioxide Particles in Synovial Fluid Samples Drops after European Union Ban

“…The collection started during the transitional period. We earlier published a dataset of patient samples collected and analyzed before the titanium dioxide ban, and reported a prevalence of 14%, although this was not a representative cohort [9]. Due to the large average size of the particles, we suspect that the identified particles were A total of 302 samples from patients with swollen joints were analyzed with a H-iRPolM Raman Spectrometer for the presence of TiO 2 .…”

“…Next to their presence in the brain stem [4], TiO 2 particles have also been identified in synovial fluid samples from patients with swollen joints, including in an ankle of a patient with a suspected gout flare [9,10]. Synovial fluid is a protein-rich viscous fluid present as a thin layer in joint spaces.…”

Hyperspectral Imaging Algorithms and Applications: A Review

“…The results show accurate identification of normal gingiva, mild, moderate, and severe periodontitis, offering a precise means of disease staging with potential clinical applications. In [173], the study investigates the use of Raman hyperspectral imaging (HRI) as an alternative to compensated polarized light microscopy (CPLM) for identifying synovial crystals in rheumatic diseases. It detected various crystals, including classical and novel ones, offering advantages over CPLM and potential for discovering new crystal-based diseases, improving diagnostic accuracy, and monitoring.…”

Real-time and accurate calibration detection of gout stones based on terahertz and Raman spectroscopy

“…Zhu et al (2022) used a portable Raman system to analyze urine stone samples obtained from 300 patients and demonstrated that Raman spectroscopy can be applied to portable automated analysis systems, which have the characteristics of simple operation, easy automation, and rapid detection in on-site clinical environments. Niessink et al (2023) measured the crystals in joint synovial fluid using Raman spectroscopy, which indicated that Raman technology could be used to evaluate disease conditions or predict the formation of stones. These studies demonstrate that Raman spectroscopy technology provides a fast and convenient method for medical detection.…”