Imaging features and pathologic characteristics of ovarian thecoma.

OBJECTIVE: To analyze the imaging findings of ovarian thecoma and to better understand the tumor features based on aspect of computed tomography and magnetic resonance images. METHODS: Nineteen ovarian thecomas confirmed by histopathologic examination were analyzed retrospectively. Image characteristics were analyzed and compared with those of the pathologic features. RESULTS: The mean diameter of tumors was 9.6 cm. The masses were well defined (n = 17) or ill defined (n = 2) and appeared solid with cystic areas (n = 11), entirely solid (n = 4), or cystic with solid components (n = 4). On T2-weighted/spectral adiabatic inversion recovery (T2WI/SPAIR) images, 12 cases appeared isointense or slightly hyperintense. Of the 12 cases, 8 had patchy hypersignal areas. On computed tomographic images, 7 cases showed hypodensity or isodensity. All tumors exhibited mild enhancement. On pathologic examination, the tumor was composed of spindle cells with a moderate amount of cytoplasm. CONCLUSION: Imaging manifestations of ovarian thecoma are various and nonspecific. However, a large, well-defined mildly enhanced solid mass with cystic areas and especially isointense or slightly hyperintense on T2WI/SPAIR sequence in pelvic cavity may suggest the diagnosis of ovarian thecoma.

In vivo DTI longitudinal measurements of acute sciatic nerve traction injury and the association with pathological and functional changes.

OBJECTIVE: To explore the feasibility of longitudinally measuring acute traction injury to the sciatic nerve using 1.5 T clinical MRI scanner of diffusion tensor imaging (DTI) and to analyze the associations of the measurements [regarding fractional anisotropy (FA), apparent diffusion coefficient (ADC), eigenvalue (λ|| and λ⊥)] with limb function and pathology. MATERIALS AND METHODS: Acute traction injuries to the sciatic nerve were created in the right hind limbs of 32 New Zealand white rabbits, the left hind limbs were chosen as sham operation nerves. MRI scans were performed at intervals from pre-operation through 8 weeks post-operation follow up. Scanning sequences included T2WI, STIR, and single shot spin echo DTI with single shot EPI acquisition (SE-DTI-SSEPI). Parameters of FA, ADC, axial diffusivity (λ||) and radial diffusivity (λ⊥) were then calculated from the DTI. The limb functions and pathologic changes were evaluated and compared. RESULTS: Diffusion Tensor Tractography (DTT) only revealed the proximal portion of the injured nerves 1-3 days after traction injury but did not reveal the nerve of the distal and traction portions at all. Nerve fibers of the distal and traction portions were not revealed by DTT until after the 1st week. They were elongated gradually and recovered almost to the normal at 8th week. The value of FA and λ⊥of the injured nerves, which varied in different portions, were significantly different between the traction injury nerves and the sham operation nerves, whereas the value of ADC and λ|| were not significantly different. The curve lines of FA value-time for the proximal, traction and distal portions of the injured nerve correlated well to the functional and pathological changes of the limb affected, while the DTI parameters did not change that much in the sham-operated nerves. CONCLUSIONS: DTI obtained on a 1.5 T clinical MRI scanner can demonstrate early abnormal changes following traction injury to the sciatic nerve in rabbits. The curve lines of FA-time and λ⊥-time for nerve traction injury are consistent with the pathological and functional changes of the limb affected. DTI may thus be a sensitive and reliable method to evaluate degeneration and regeneration of the nerve after traction injury.