Diagnostic advances in synovial fluid analysis and radiographic identification for crystalline arthritis

Abstract

Purpose of review: This review addresses diagnostic methods for crystalline arthritis including synovial fluid analysis, ultrasound and dual energy CT scan (DECT). Recent findings:There are new technologies on the horizon to improve the ease, sensitivity and specificity of synovial fluid analysis. Raman spectroscopy uses the spectral signature that results from a material's unique energy absorption and scatter for crystal identification. Lens-free microscopy directly images synovial fluid aspirate on to a complementary metal-oxide semiconductor (CMOS) chip, providing a high-resolution, wide field of view (~20 mm 2 ) image. Raman spectroscopy and lens-free microscopy may provide additional benefit over compensated polarized light microscopy (CPLM) synovial fluid analysis by quantifying crystal density in synovial fluid samples. Ultrasound and DECT have good sensitivity and specificity for the identification of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals. However, both have limitations in patients with recent onset gout and low urate burdens.Summary: New technologies promise improved methods for detection of MSU and CPP crystals. At this time, limitations of these technologies do not replace the need for synovial fluid aspiration for confirmation of crystal detection. None of these technologies address the often concomitant indication to rule out infectious arthritis.

The diagnostic value of conventional radiography and musculoskeletal ultrasonography in calcium pyrophosphate deposition disease: a systematic literature review and meta-analysis

“…In daily clinical practice, imaging techniques play a central role in the diagnosis of CPPD given the fact that SFA may sometimes be difficult to perform 5 .…”

Ultrasonography and dual-energy computed tomography: impact for the detection of gouty deposits

“…The snowstorm sign is caused by hyperechoic microtophi within a joint effusion. The differential diagnosis includes debris in an osteoarthritic joint or synovial chondromatosis, which can have a similar appearance to the snowstorm sign, as described by several authors [ 33 - 36 ]. Aggregates and tophi are most useful when seen in conjunction with the DC sign.…”

Presence of Crystals in the Synovial Fluid of Patients With Psoriatic Arthritis

“…B. Critical assessment of counting molded elements -the total and differential number of white blood cells in synovial fluid provides a way of distinguishing between noninflammatory and inflammatory arthritis, neutrophil rates are a good guide to the degree of inflammation of the joints and therefore an indicator of severe acute conditions (15,18) C. Critical assessment of the identification of MSU, CPPD crystals, etc. through polarized light microscopy -analysis of the sensitivity, specificity and reliability tests of crystals shows alarming problems and variations (15,16,19,20).…”