The distal femoral epiphyseal secondary ossification center (DFE), which can be reliably identified and measured sonographically, may assist the sonologist in predicting third-trimester menstrual age. Between 28 and 35 menstrual weeks, the percentage of fetuses with a DFE progressively increases. Although the mean age at DFE appearance is approximately 32-33 menstrual weeks, the DFE may be seen as early as 29 menstrual weeks. Nevertheless, the age of a fetus without an identifiable DFE is most likely less than or equal to 34 menstrual weeks. Measurements of the DFE show that its size increases linearly: the menstrual age of a fetus whose DFE measures greater than or equal to 7mm is most likely greater than or equal to 37 weeks.
The potential role of magnetic resonance (MR) imaging in the diagnosis and local staging of testicular tumors was evaluated in 23 patients who subsequently underwent surgery or biopsy. Findings at MR imaging were compared with those at ultrasonography (US) and were correlated with the surgical-histologic findings. At surgery, three patients were found to have extratesticular and 20 patients intratesticular abnormalities. This distinction had been correctly made with both imaging modalities, but US did not demonstrate the intratesticular abnormality in four patients with diffuse infiltrating tumors. Neither modality allowed differentiation of benign from malignant disorders. When local tumor staging was analyzed in 11 patients, the accuracy of both modalities was disappointing (true-positive findings with MR imaging in seven patients and with US in five). At present, US remains the primary imaging modality for testicular disease. MR imaging should be employed when findings at physical examination and US are discrepant and considered when diffuse infiltrative disease is suspected.
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