Lhermitte-Duclos disease (LDD) is a disorder sometimes referred to as a dysplastic gangliocytoma of the cerebellum. This is a focally indolent growth of the cerebellar cortex in which the folia enlarge due to a profusion of dysplastic cortical neurons and a thickening of the molecular layer. Loss of Purkinje cells and thinning of medullary white matter results. The enlarged folia lose their secondary foldings and asymmetrically expand the cerebellar hemisphere. These morphologic features produce a characteristic pattern on some CTs and all MRIs, affording an opportunity for a preoperative diagnosis. MRI of a pathologic specimen suggested that the abnormal T1 and T2 signals corresponded to the atrophic folial white matter, thickened granule cell layer, and outer molecular layer. Because of inherent Hounsfield artifact in posterior fossa with CT, MRI is the imaging modality of choice, with better visualized striated pattern. The uniqueness of these imaging features obviates the need for an obligatory biopsy for asymptomatic patients and either permits more definitive planning for surgical decompression or, in restricted lesions, guides more assuredly complete excision of the cerebellar mass.

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We retrospectively reviewed the myelograms of 433 patients and identified those who had no symptoms or signs referable to the thoracic cord, roots, or nerves. By post-myelography computed tomographic scan criteria, our frequency of asymptomatic thoracic herniated dises (ATHDs) was calculated. Post-myelography computed tomographic scans of 68 ATHDs were analyzed. Their imaging characteristics were compared with our own series of 5 symptomatic thoracic herniated discs and symptomatic thoracic herniated discs in the literature. We were unable to identify any imaging features that could reliably classify a disc as an ATHD or a symptomatic thoracic herniated disc. Our results call into question the propriety of prophylactic surgery for ATHDs, even when the lesions are radiographically impressive.

Osteochondromas represent a hyperplastic-dysplastic disturbance of bone from progressive endochondral ossification. The tumors slowly enlarge, creating insidious but progressive symptoms. Magnetic resonance imaging, computed tomography, and postmyelogram computed tomography are useful in evaluating the size and extent of spinal osteochondromas as a cause of spinal cord compression.

The introduction of computed tomography (CT) in 1972 revolutionized the radiographic evaluation of patients who have experienced trauma. However, panoramic tomography (PT) continued to be superior in sensitivity to CT in the identification of mandible fractures and has been considered the gold standard for the past 3 decades. In 1989, a faster, higher-resolution spiral or helical CT (HCT) became widely available, and its efficacy in multiplanar evaluation and diagnosis of fractures of the upper two thirds of the face has been well established. The sensitivity of this new-generation HCT in comparison to PT in the detection of mandible fractures has not been determined. The purpose of this study was to compare the sensitivity, physician interpretation error, and interphysician agreement of HCT and PT in the identification of mandible fractures. The number and anatomical location of mandible fractures identified by HCT and PT was not significantly different. However, the number and location of 96% of fractures identified by HCT was agreed on by neuroradiologists compared with only 91% of fractures identified by PT. Furthermore, the interphysician agreement when no fracture was identified was 96% by HCT versus only 81% by PT. In conclusion, HCT has enhanced imaging quality, equivalent sensitivity in identification of fractures, decreased interpretation error, and greater interphysician agreement in the identification of mandible fractures. HCT has surpassed PT as the current gold standard for the radiographic evaluation and diagnosis of mandible fractures.

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