Hee Kyung Kim MD, Abstract Co-Author: Nothing to Disclose

Arnold Carlson Merrow MD, Abstract Co-Author: Author for Amirsys, Inc

Suraj Serai PhD, Abstract Co-Author: Nothing to Disclose

Shelia Salisbury PhD, Abstract Co-Author: Stockholder, Angiodynamics, Inc Stockholder, Apricus Biosciences, Inc Stockholder, BioClinica, Inc Stockholder, Optic Circuits Ltd Stockholder, Computerized Thermal Imaging, Inc Stockholder, CytRx Corporation Stockholder, General Electric Company Stockholder, Orchid Cellmark, Inc Stockholder, Poniard Pharmaceuticals, Inc Stockholder, RXI Pharmaceuticals Corporation Stockholder, Retractable Technologies, Inc Stockholder, Targeted Genetics Corporation Stockholder, Women First Healthcare, Inc Stockholder, YM Bioscience Inc Stockholder, OSI Pharmaceuticals, Inc

Lily L. Wang MBBS, Presenter: Nothing to Disclose

Tal Laor MD, Abstract Co-Author: Nothing to Disclose

Brenda Wong, Abstract Co-Author: Nothing to Disclose

Muscular dystrophy and other muscular disorders can have age- or disease duration-related changes in skeletal muscle due to their progressive nature. Objective measurements of muscular fat and inflammation are important for establishing diagnoses and assessing the therapeutic responses in these diseases. In order to identify disease-related changes, normative values must be determined. Therefore, the purpose of this study is to identity the normal range of T2 relaxation time (T2 values) of skeletal muscles on MRI in healthy children, to identify the correlation between child age and T2 values in skeletal muscles, and to identify the correlation between BSA and T2 values in skeletal muscle.

IRB approval and informed consent were obtained. Nineteen healthy boys were evaluated, age range: 7-17 years, mean: 14.2 ±2.7 years. Pelvic MRI exams were obtained which included axial T1-weighted images (WI), axial T2-WI with fat saturation (FS), and axial T2 maps with and without FS. Fatty infiltration and inflammation of the right gluteus maximus muscles were graded on T1 WI and T2 WI with FS, respectively. Mean T2 values of the right gluteus maximus muscles from the T2 maps with FS (T2 I) were used as an index of the water content of the muscles. Differences between T2 maps with and without FS (∆ T2) were used as an index of the fat content of the muscles. Age and BSA were obtained for each patient; BSA was calculated from the height and weight.

All 19 boys showed minimal fatty infiltration of the gluteus maximus muscle on T1 WI, and none of 19 boys showed inflammation on T2 WI with FS. T2 I ranged from 41.2 to 48.4 msec (mean: 45.0 ± 2 msec). ∆ T2 ranged from 2.8 to 21.6 msec (mean 7.4 ± 2.6 msec). There was no signification correlation between T2 I and age (p= 0.60), T2 I and BSA (p= 0.91), ∆ T2 and age (p=0.77), or ∆ T2 and BSA (p=0.07). There was significant correlation between age and BSA (p<0.05).

While there is significant positive correlation between BSA and age, neither age nor BSA affects the amount of physiologic water or fat of normal skeletal muscles in children.

Regardless of age and BSA, T2 values of muscles in normal children can be used as normal reference values to determine the degree of abnormal fatty infiltration and inflammation in muscular diseases.

Kim, H, Merrow, A, Serai, S, Salisbury, S, Wang, L, Laor, T, Wong, B, Do Age and BSA (Body Surface Area) Affect the T2 Relaxation Time Value on MRI of Skeletal Muscles in Normal Children?.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11013389.html