OBJECTIVE: Small venous air emboli probably occur frequently. Our purpose was to describe the locations of small venous air emboli detected on CT scans of the head and neck and their clinical presentations. MATERIALS AND METHODS: The head CT scans of 17 patients and neck CT scans of 10 patients with suspected venous air emboli were reviewed and the locations of the gas collections were recorded. The charts of these patients were reviewed to identify possible sources of these gas collections and any symptoms they may have produced. RESULTS: The most likely source of these gas collections was venous air emboli. The neck CT scans demonstrated gas in the inferior internal jugular vein, subclavian vein, and small anterior neck veins. The head CT scans demonstrated gas in the cavernous sinus, the frontal and temporal scalp, the infratemporal fossa, the carotid canal, the straight sinus, the superior ophthalmic vein, the superior sagittal sinus, extracranially in the region of the foramen magnum, and in a canal in the skull base for an emissary vein or the inferior petrosal sinus. Most of the intravenous lines were placed within 6 h of the scans demonstrating gas. The gas collections did not produce symptoms. CONCLUSION: Asymptomatic venous air emboli can be identified in several locations in the head and neck. The time between manipulation of intravenous lines and the scan, the position of the patient, and the anatomy of the patient probably all affect the likelihood of identifying venous air emboli on CT scans.

Embolism, Air↗

PubMedDate not supplied

MR enhancing brain lesions in methanol intoxication.

Methanol intoxication can cause necrosis of the putamen and subcortical white matter that is evident on neuroimaging. We report a 47-year-old man with significant methanol intoxication who had enhancing lesions in the caudate nuclei, putamina, hypothalamus, and subcortical white matter by MRI. This case demonstrates that contrast enhancement of brain lesions can be observed after methanol poisoning.

Brain Diseases↗

PubMedDate not supplied

Anatomy of the facial and vestibulocochlear nerves in the internal auditory canal.

PURPOSE: To define the anatomy of the facial and vestibulocochlear nerves in the internal auditory canal on parasagittal CT scans of cadaveric specimens and to compare this anatomy with findings on in vivo T2-weighted two-dimensional fast spin-echo and three-dimensional turbo spin-echo MR images. METHODS: Thirty-eight formalin-fixed cadaveric temporal bones were examined with 1-mm-thick contiguous parasagittal CT sections to determine the anatomy of the nerves in the internal auditory canal. Ten specimens underwent limited dissection. Fourteen canals in 12 patients were examined with T2-weighted two-dimensional fast spin-echo oblique parasagittal MR imaging and 12 canals in 8 patients were examined with T2-weighted three-dimensional turbo spin-echo MR imaging. The anatomy depicted on MR images was compared with the cadaveric anatomy. RESULTS: On cadaveric specimens, the facial nerve coursed superior and anterior to the vestibulocochlear nerve as a tubular structure throughout the length of the canal. The vestibulocochlear nerve entered the canal as a tubular structure but became crescent shaped in cross section in the middle portion of the canal and separated into individual nerves only in the most lateral portion of the canal. The anatomy of the nerves differed among the specimens. Similar anatomy was demonstrated by MR imaging. CONCLUSION: The ability to define the nerves in the internal auditory canal in the parasagittal plane may provide greater sensitivity and specificity in identifying abnormalities of this anatomic structure.

Ear, Inner↗

PubMedDate not supplied

T2-weighted three-dimensional turbo spin-echo MR of intracranial aneurysms.

A T2-weighted three-dimensional turbo spin-echo sequence is described that accurately depicted the anatomy of 18 intracranial aneurysms in 10 patients.

Arteries↗