We retrospectively reviewed 330 T1-weighted sagittal images, 80 T2-weighted sagittal images, and 83 gadopentetate-dimeglumine-enhanced scans of normal adults to determine the MR appearance of the normal adult clivus. MR images of 21 patients with an abnormal clivus (19 with tumor invasion and two with marrow reconversion) were also evaluated restrospectively and compared with those of the control group to assess MR features distinguishing the two groups. Our study revealed that a normal adult clivus consisted of low- and high-intensity portions mixed in various proportions on T1-weighted images. The low-intensity portion was isointense or hyperintense relative to the pons and always contained foci of bright signal intensity. The low-intensity tumor of a pathologic clivus tended to be hypointense relative to the pons (17/19), and was completely devoid of foci of bright signal intensity. The normal adult clivus was approximately isointense relative to the pons on T2-weighted images. Clival tumors were grossly hyperintense relative to the pons on T2-weighted images in 11 of 17 patients. In the remaining six patients, either a portion of or the entire lesion was isointense relative to the pons and, therefore, was not detectable on T2-weighted images. A normal adult clivus can enhance to some degree (19/83). Clival tumors were found to enhance intensely. A clivus of very low signal intensity (signal void) on T1- or T2-weighted images was always abnormal. The clivus with marrow reconversion was uniformly hypointense relative to the pons on T1-weighted images and isointense relative to normal marrow on T2-weighted images.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Osteocartilaginous tumors in the parapharyngeal space arising from bone exostoses.

Three osteocartilaginous tumors that arose from bone stalks were diagnosed by the demonstration, on multiplanar cross-sectional CT and MR images, of the site of stalk attachment to the adjacent mandible (one), skull base (one), and cervical vertebra (one). All three patients presented with signs and symptoms related to mass effect in the parapharyngeal region. Mass effect was more pronounced in the two cases of malignant degeneration (osteosarcoma, chondrosarcoma) than in the single case of benign osteocartilaginous exostosis. Differentiation of benign from malignant osteocartilaginous tumor may be accomplished by appreciating characteristic CT and MR features of the cartilage cap. The differential diagnosis of mass lesions of the parapharyngeal space should include tumors of osteocartilaginous origin.

Adolescent↗