Optical clearing of articular cartilage: A comparison of clearing agents

Alexander Bykov, Tapio Hautala, Matti Kinnunen, Alexey Popov, Sakari Karhula, Simo Saarakkala, Miika T. Nieminen, Valery Tuchin

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

3 Citations (Scopus)


Optical clearing technique was applied to the problem of OCT imaging of articular cartilage and subchondral bone. We show that optical clearing significantly enhances visualization of articular cartilage and cartilage-bone interface. The effect of different clearing agents was analyzed. For the clearing, iohexol solution and propylene glycol (PG) were used. Clearing was performed in vitro at room temperature by immersion method. Cylindrical osteochondral samples (d=4.8mm) were drilled from bovine lateral femur and stored in phosphate-buffered saline at-20°C until clearing. Monitoring of clearing process was performed using high-speed spectral-domain OCT system providing axial resolution of 5.8 μm at 930nm. Total duration of experiment was 90-100min to ensure saturation of clearing. We have shown that iohexol solution and PG are capable to optically clear articular cartilage enabling reliable characterization of cartilagebone interface with OCT. Being a low osmolarity agent, iohexol provides minimal changes to the thickness of cartilage sample. Clearing saturation time for the cartilage sample with the thickness of 0.9 mm measured with OCT is of 50 min. However, less than 15 min is enough to reliably detect the rear cartilage boundary. Alternatively, PG significantly (60%) reduces the cartilage thickness enabling better visualization of subchondral bone. It was observed that PG has higher clearing rate. The clearing saturation time is of 30 min, however less than 5 min is enough to detect cartilage-bone interface. We conclude that iohexol solution is superior for OCT imaging of cartilage and cartilage-bone interface, while PG suits better for subhondral bone visualization.

Original languageEnglish
Title of host publicationNovel Biophotonics Techniques and Applications III
EditorsArjen Amelink, I. Alex Vitkin
PublisherInternational Society for Optics and Photonics SPIE
ISBN (Print)978-1-6284-1705-0
Publication statusPublished - 1 Jan 2015
MoE publication typeNot Eligible
EventNovel Biophotonics Techniques and Applications III - Munich, Germany
Duration: 24 Jun 201525 Jun 2015

Publication series

SeriesProgress in Biomedical Optics and Imaging
SeriesProceedings of SPIE


ConferenceNovel Biophotonics Techniques and Applications III


  • articular cartilage
  • optical clearing
  • Optical Coherence Tomography (OCT)
  • osteoarthritis
  • subchondral bone


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