Quantitative imaging of excised osteoarthritic cartilage using spectral CT.
OBJECTIVES
To quantify iodine uptake in articular cartilage as a marker of glycosaminoglycan (GAG) content using multi-energy spectral CT.


METHODS
We incubated a 25-mm strip of excised osteoarthritic human tibial plateau in 50 % ionic iodine contrast and imaged it using a small-animal spectral scanner with a cadmium telluride photon-processing detector to quantify the iodine through the thickness of the articular cartilage. We imaged both spectroscopic phantoms and osteoarthritic tibial plateau samples. The iodine distribution as an inverse marker of GAG content was presented in the form of 2D and 3D images after applying a basis material decomposition technique to separate iodine in cartilage from bone. We compared this result with a histological section stained for GAG.


RESULTS
The iodine in cartilage could be distinguished from subchondral bone and quantified using multi-energy CT. The articular cartilage showed variation in iodine concentration throughout its thickness which appeared to be inversely related to GAG distribution observed in histological sections.


CONCLUSIONS
Multi-energy CT can quantify ionic iodine contrast (as a marker of GAG content) within articular cartilage and distinguish it from bone by exploiting the energy-specific attenuation profiles of the associated materials.


KEY POINTS
• Contrast-enhanced articular cartilage and subchondral bone can be distinguished using multi-energy CT. • Iodine as a marker of glycosaminoglycan content is quantifiable with multi-energy CT. • Multi-energy CT could track alterations in GAG content occurring in osteoarthritis.
['Rajendran|Kishore|K|', 'Löbker|Caroline|C|', 'Schon|Benjamin S|BS|', 'Bateman|Christopher J|CJ|', 'Younis|Raja Aamir|RA|', 'de Ruiter|Niels J A|NJ|', 'Chernoglazov|Alex I|AI|', 'Ramyar|Mohsen|M|', 'Hooper|Gary J|GJ|', 'Butler|Anthony P H|AP|', 'Woodfield|Tim B F|TB|', 'Anderson|Nigel G|NG|']
D002358:Cartilage, Articular D003287:Contrast Media D004210:Dissection D006025:Glycosaminoglycans D006801:Humans D007455:Iodine D010003:Osteoarthritis D019047:Phantoms, Imaging D013977:Tibia D014057:Tomography, X-Ray Computed
Spectral CT Articular cartilage Glycosaminoglycan Osteoarthritis Ionic contrast media