Rafael Mauricio Jimenez MD, Presenter: Nothing to Disclose

Andrea Hernandez MD, Abstract Co-Author: Nothing to Disclose

Diana Marin MD, Abstract Co-Author: Nothing to Disclose

Stephen M. Henesch DO, Abstract Co-Author: Nothing to Disclose

Diego Jaramillo MD, MPH, Abstract Co-Author: Nothing to Disclose

The trochlear preossification can present on T2-weighted images as a focus of high signal intensity and can be confused with different pathologies. We will characterize the MR characteristics of the trochlear preossification center according to age, gender, imaging characteristics and time of appearance.

The study subjects were selected from the musculoskeletal MR examinations database performed over a period of nine years. We studied sixty four consecutive MR images of the elbow in children between 6 months and 12 years. The signal characteristics of the trochlea were blindly categorized by 3 experienced Radiologist on the basis of signal intensity on T1, T2 and Gradient echo sequences within the epiphyseal cartilage. Subjects’ age and corrected age were compared to the trochlear ossification center stages using Analysis of variances followed by pairwise comparisons using Bonferroni methods. Data was reported by mean ± Standard deviation (SD) for continues variables and frequency distribution for categorical variables.

We observed sequential MR development of the trochlear region for 61 subjects. No significant differences were seen between males and females in regard to age (7.4 ± 3.06, 6.0 ± 3.51 p=.10, respectively) and corrected age. The ossification center was preceded by the appearance of the preossification center. We found a total of 18 preossification centers. The statistical analysis showed there was a significantly different age of appearance of the trochlear preossification center when compared to the ossification center (p=0.004). The average age of the appearance of the preossification center at the trochlea was 6.7 ±3.6 years. The average age of the appearance of the ossification center at the trochlea was 11±0.7 years . The typical signal characteristics of a preossification center is hyperintense in both T2 weighted images and Gradient Echo images.

There is an expected age-related progression in MR imaging signal intensity within the trochlea. The pre-ossification center appears at a statistically significant earlier age than the ossification center and shows very different signal characteristics.

The preossification center of the trochlea is a well visualized MR precursor of the ossification center and should not be confused with inflammatory, infectious or traumatic pathologies.

Jimenez, R, Hernandez, A, Marin, D, Henesch, S, Jaramillo, D, MRI Identification and Characterization of the Trochlear Preossification Center, an Area of Cartilaginous Change That Precedes the Appearance of the Secondary Ossification Center.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6009973.html