Jutta Ellermann MD, PhD, Presenter: Nothing to Disclose

Stanislav Spiridonov, Abstract Co-Author: Nothing to Disclose

Patrick Morgan MD, Abstract Co-Author: Nothing to Disclose

Hip MRI studies are increasingly used to diagnose femoroacetabular impingement (FAI). However, even today’s state-of-the-art imaging is insufficient for predicting articular cartilage abnormalities as diagnosed on arthroscopy. In this feasibility study, we investigate if quantitative cartilage T2*-mapping adds valuable information to the interpretation of clinical hip MRI studies.

MRI was performed at 3T. Following the intraarticular administration of Gadolinium a conventional clinical MRI Hip Imaging Protocol was performed. Fourteen symptomatic patients were included in this HIPPA compliant study, using Proton Density, T1- and T2-weighted Turbo Spin Echo images. Subsequently T2*-weighted images were collected in 7 oblique sagittal slices (resolution 0.5x0.5x3mm3; TE = 4.2, 11.3, 18.4, 25.6 and 32.7 ms, respectively, TR = 1040 ms, field of view 18 x 18 cm2). Following the acquisition of the T2* data, the T2* maps were calculated.

Conventional MRI depicted the spectrum of imaging findings associated with femoroacetabular impingement. T2* maps in the sagittal oblique plane (Fig. 1) reveal decreased values in the area of cartilage abnormality (20.86 ms, SD 5.2). These values compare to 32.57 ms (SD 7.2) within the articular cartilage of the central aspect of the femoral head, which was comparable to the T2* values of acetabular cartilage in healthy young adults. The p value for the difference between the acetabular and femoral zone is p<001. Arthroscopic correlation at the time of labral repair, revealed high-grade cartilage abnormalities in the area of decreased T2* values in the anterosuperior labrum.

In the past decade the ability to surgically intervene in patients with FAI has outpaced the ability to identify the patients that will most benefit from these interventions. The conventional TSE images in this study clearly revealed the labral tear. However, the extent of the cartilage injury is not fully appreciated. Our preliminary results, using T2* mapping to further biochemically probe cartilage integrity in patients with arthroscopically proven femoroacetabular impingement indicate clear depiction of lower than normal values in areas of cartilage degeneration.

The ability to surgical intervene has outpaced the ability to identify the patients with FAI that will benefit most. There is a need for improved qualitative and quantitative imaging protocols.

Ellermann, J, Spiridonov, S, Morgan, P, Quantitative T2* Mapping for Improved Cartilage Assessment in Femoroacetabular Impingement: A Feasibility Study.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012130.html