Kevin Macwan, Presenter: Nothing to Disclose

Andrea Schwarz Doria MD, Abstract Co-Author: Nothing to Disclose

Elka Miller MD, Abstract Co-Author: Nothing to Disclose

Harpal Gahunia, Abstract Co-Author: Nothing to Disclose

Anguo Zhong, Abstract Co-Author: Nothing to Disclose

Afsaneh Amirabadi PhD, Abstract Co-Author: Nothing to Disclose

When recognized and treated early, symptoms of hemophilia can be greatly reduced and joint degeneration avoided. Treatment however, must begin before macroscopic lesions develop in the joint cartilage. The study objective was to determine the effects of a limited (n=2, Group 2) vs. a more extensive (n=8, Group 1) number of joint bleeds vs. no prior bleeds (Group 3) on the development of knee joint cartilage degeneration in a rabbit model by using T1 and T2 maps as surrogate imaging techniques for assessment of early cartilage damage.

Juvenile male rabbits (n=21) were randomized into 3 groups (n=9: Groups 1 and 2; n=3 Group 3) and subject to autologous blood injections in one knee to simulate hemophilic arthropathy. Group 1: injections on week 1, 5, 7, 9, 11, 13, 15 and 17; Group 2: injections on week 1 and 17; Group 3: no injections. Rabbits were MR imaged (unenhanced T1 and short TR T2 map) at 1.5 T on weeks 0, 5 and 17 of the study, then euthanized on week 17. T1 maps were compared with cartilage proteoglycan content and T2 map with the degree of collagen organization [polarized light microscopy (picrosirus staining)] in corresponding histologic specimens.

On week 5, a borderline difference was noted between groups 1 and 3 for T2 (P=0.056) and T1 map values (P=0.055) suggesting that even a minimal amount of intra-articular bleeds causes functional cartilage changes. On week 17, significant differences were noted between groups 1 and 3 for T2 (lateral femoral condyle, P<0.0001; medial femoral condyle, P=0.01) and T1 (lateral femoral condyle, P=0.03; medial femoral condyle, P=0.055) map values suggesting that the interval of time plays a role in determining presence of cartilage changes. T1 and T2 maps correlated well with corresponding histology.

Even minimal amounts of intra-articular bleeds cause micro-structural cartilage deterioration within the knee joint. Interval of time between the bleeding episode and imaging is a determinant of cartilage damage. Both T1 and T2 maps can be used as surrogate imaging techniques for assessment and follow-up of early cartilage changes in hemophilic joints.

The use of T2 and T1 mapping as surrogate imaging techniques for assessment of early cartilage changes can assist physicians as a cost-effective prophylaxis for hemophilic arthropathy.

Macwan, K, Doria, A, Miller, E, Gahunia, H, Zhong, A, Amirabadi, A, T1 and T2 Maps as Surrogate Imaging Techniques for Physiologic Characterization of Cartilage Damage in a Rabbit Model of Hemophilic Arthropathy.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9015286.html