MRI for occult physeal fracture detection in children and adolescents.

BACKGROUND: Conventional radiography has limitations in the detection of physeal fractures before the closure of the physis occurs. Fracture detection may be improved by using magnetic resonance imaging (MRI). PURPOSE: To evaluate the usefulness of MRI for the detection of occult fractures involving the physis when radiography results are negative. MATERIAL AND METHODS: In this prospective study, 24 children (age range, 3-15 years; mean age, 10.7 years) received MRI if they met the following criteria: acute joint trauma, swelling and tenderness around the joint, limitations in bearing weight, an open physis, and negative radiography results for fractures. Fractures revealed by the MRI were classified according to the Salter-Harris classification system. Joint effusion, bone marrow edema, and periosteal alterations were graded on a three-point scale. The non-parametric Wilcoxon test and Fisher's exact test were used for the statistical evaluation. RESULTS: From a total of 24 MR data-sets, 23 were evaluated (one patient was excluded due to poor MR image quality). Elbow injuries were present in 10 patients (43.5%), distal tibia injuries in 10 patients (43.5%), and distal femur injuries in three patients (13%). MRI results excluded physeal fractures in 15 (65.2%) of the 23 children. An occult physeal fracture was detected with MRI in eight (34.8%) patients; of these, five (21.7%) had fractures of the elbow, two (8.7%) had fractures of the distal tibia, and one (4.3%) had a fracture of the distal femur. All of the patients with fractures and 11 of the 15 patients without fractures demonstrated bone marrow edema. CONCLUSION: The frequency of occult fracture, as detected by MRI, was 34.8%. Thus, MRI is a useful additional imaging method for the detection of occult fractures when radiography is negative.

Differentiation of adrenal adenomas from metastases with unenhanced computed tomography.

OBJECTIVE: To investigate whether the diagnostic accuracy of unenhanced computed tomography (CT) regarding the differentiation of adrenal adenomas from adrenal metastases is increased by applying a combination of morphologic criteria instead of only measuring the density values of the tumor. PATIENTS AND METHODS: Unenhanced CT scans of 56 patients with an adrenal mass and a history of an extra-adrenal malignancy were analyzed for size, attenuation, contour, and structure characteristics of the adrenal tumor. Coefficients yielded by multiple logistic regression analysis were used for the construction of an additive total score (score S) that included several diagnostic criteria. The reliability of the total score and all parameter combinations was tested by receiver operating characteristic (ROC) analysis. The nature of the adrenal lesion was determined by follow-up CT (40 patients), percutaneous biopsy (15 patients), or surgery (1 patient). Twenty-four of the neoplasms were adenomas, and 32 were found to be metastases. RESULTS: The score of the combined CT parameters showed the largest area under the ROC curve. The highest predictive power indicated by the model was calculated at a cutoff value of 7.05, with a sensitivity of 100% and a specificity of 96.8% for the detection of metastases. At 6.85 points as the cutoff value, the scoring system still maintained a sensitivity of 95.8% and a specificity of 96.9%. CONCLUSION: The differentiation between adrenal adenomas and metastases is improved by applying our scoring system compared with any single parameter alone. The total score is obtained by adding 10% of the density values to the size in centimeters, plus 2 if the contour of the lesion is blurred and plus 1 if the structure is inhomogeneous. By setting the threshold at 7 points, all but 1 lesion were classified correctly.