Heejin Park MD, Abstract Co-Author: Nothing to Disclose

Ji Hyun Kim, Presenter: Nothing to Disclose

So-Yeon Lee MD, Abstract Co-Author: Nothing to Disclose

Eun Chul Chung MD, PhD, Abstract Co-Author: Nothing to Disclose

(1) To compare the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and quality of two different methods of imaging that include iterative decomposition of water and fat in the articular cartilage of the knee: echo asymmetry and least-squares estimation with 3D spoiled gradient echo (IDEAL 3D SPGR) and conventional 3.0 T fast spin-echo T2 fat saturation (FSE T2 FS) imaging. (2) To evaluate the utility of IDEAL 3D SPGR for imaging.

Forty-five patients underwent 3.0T MR imaging by IDEAL 3D SPGR and FSE T2 FS and were retrospectively analyzed. The SNR and CNR of the patellar and femoral cartilages were measured and calculated. Two musculoskeletal radiologists performed subjective scoring of all images for three measures: general image quality, fat saturation, and cartilage evaluation. Inter-observer agreement between the two radiologists was analyzed using kappa statistics, and the subjective scores were analyzed using the Wilcoxon signed rank test. SNR and CNR values were compared by paired Student’s t-tests.

The mean SNRs of the patellar and femoral cartilages were 90% and 66% higher, respectively, for IDEAL 3D SPGR than for FSE T2 FS. The CNRs of the patellar cartilages and joint fluids were 2.4 times higher for FSE T2 FS than for IDEAL 3D SPGR, and the CNR between the femoral cartilage and joint fluid was 2.2 times higher for FSE T2 FS than for IDEAL 3D SPGR. Inter-observer agreement was fair for general image quality of both IDEAL 3D SPGR and FSE T2 FS (kappa values = 0.343, 0.328) and for fat saturation of FSE T2 FS (0.343) and cartilage evaluation of IDEAL 3D SPGR (0.308), while the inter-observer agreements for other measures were slight or poor. General image quality and fat saturation were superior using FSE T2 FS compared to those of IDEAL 3D SPGR imaging according to both readers, while cartilage evaluation was superior using IDEAL 3D SPGR.  

IDEAL 3D SPGR images show excellent visualization of the patellar and femoral cartilages in 3.0 T MR and can compensate for the weaknesses of FSE T2 FS in the evaluation of cartilage injuries. IDEAL 3D SPGR images reveal adequate fat saturation, especially when metallic devices are present in the knee; however, these images are susceptible to motion artifacts.  

This article help clinical appliance of the IDEAL image and  usefulness of the IDEAL on the evaluation of the cartilage of the knee joint  

Park, H, Kim, J, Lee, S, Chung, E, Iterative Decomposition of Water and Fat Using Echo Asymmetry and Least-Squares Estimation with a 3D Spoiled Gradient Echo (IDEAL 3D SPGR) of the Articular Cartilage of the Knee on 3.0 T MRI: A Comparison with Conventional 3.0 T Fast Spin-Echo T2 Fat.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12020666.html