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Ann Biomed Eng. 2018 Jul;46(7):1038-1046. doi: 10.1007/s10439-018-2013-y. Epub 2018 Apr 13.

Quantitative Dual Contrast CT Technique for Evaluation of Articular Cartilage Properties.

Author information

1
Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland. abhisek.bhattarai@uef.fi.
2
Diagnostic Imaging Center, Kuopio University Hospital, P.O. Box 100, FI-70029, Kuopio, Finland. abhisek.bhattarai@uef.fi.
3
Center of Oncology, Kuopio University Hospital, Kuopio, Finland.
4
Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland.
5
Diagnostic Imaging Center, Kuopio University Hospital, P.O. Box 100, FI-70029, Kuopio, Finland.
6
Department of Orthopedics, Traumatology and Hand Surgery, Kuopio University Hospital, Kuopio, Finland.
7
Departments of Biomedical Engineering, Chemistry, and Medicine, Boston University, Boston, MA, USA.
8
School of Liberal Studies and Education, Navrachana University, Vadodara, Gujarat, India.

Abstract

Impact injuries of cartilage may initiate post-traumatic degeneration, making early detection of injury imperative for timely surgical or pharmaceutical interventions. Cationic (positively-charged) CT contrast agents detect loss of cartilage proteoglycans (PGs) more sensitively than anionic (negatively-charged) or non-ionic (non-charged, i.e., electrically neutral) agents. However, degeneration related loss of PGs and increase in water content have opposite effects on the diffusion of the cationic agent, lowering its sensitivity. In contrast to cationic agents, diffusion of non-ionic agents is governed only by steric hindrance and water content of cartilage. We hypothesize that sensitivity of an iodine(I)-based cationic agent may be enhanced by simultaneous use of a non-ionic gadolinium(Gd)-based agent. We introduce a quantitative dual energy CT technique (QDECT) for simultaneous quantification of two contrast agents in cartilage. We employ this technique to improve the sensitivity of cationic CA4+ (q =+4) by normalizing its partition in cartilage with that of non-ionic gadoteridol. The technique was evaluated with measurements of contrast agent mixtures of known composition and human osteochondral samples (n = 57) after immersion (72 h) in mixture of CA4+ and gadoteridol. Samples were arthroscopically graded and biomechanically tested prior to QDECT (50/100 kV). QDECT determined contrast agent mixture compositions correlated with the true compositions (R2= 0.99, average error = 2.27%). Normalizing CA4+ partition in cartilage with that of gadoteridol improved correlation with equilibrium modulus (from ρ = 0.701 to 0.795). To conclude, QDECT enables simultaneous quantification of I and Gd contrast agents improving diagnosis of cartilage integrity and biomechanical status.

KEYWORDS:

Biomechanics; Cartilage; Cationic contrast agent; Contrast enhanced computed tomography; Dual energy CT

PMID:
29654384
DOI:
10.1007/s10439-018-2013-y
[Indexed for MEDLINE]

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