The demonstration of glomus tumours by subtraction MRI

MR Imaging of 495 Consecutive Cases with Sensorineural Hearing Loss

Purpose:

To examine patients with sensorineural hearing loss (SNHL) with MR.

Material and Methods:

495 consecutive patients with SNHL and 120 age-matched healthy controls were examined. Spin-echo (SE) and fast spin-echo (FSE) images were used with 1.5 T equipment.

Results:

An intracranial abnormality was found in 211 (42.6%) of the patients with 95 (19.2%) along the acoustic pathway. Eleven of the 95 patients had sensory hearing loss while 84 had neural hearing loss with the retrocochlear auditory pathway affected by lesions. In 62 of the 84 patients, the internal acoustic canal and cerebellopontine angle were involved. Twenty-two patients had intra-axial lesions. The controls had no pathologic changes along the auditory pathway.

Conclusion:

MR imaging in a patient with SNHL must cover the entire acoustic pathway from the cochlea to the superior temporal gyrus, and all the components of the auditory pathway should be scrutinized. The FSE-technique can be used to detect the lesions causing SNHL. FSE-sequences can replace SE-sequences.

Vagus nerve imaging with ultrasound: anatomic and in vivo validation

To provide the anatomic basis and demonstrate the reproducibility of ultrasound studies for the identification of the vagus nerve within its course in the carotid sheath in the neck, cadaveric and in vivo imaging studies were conducted. On transverse B-mode images of the neck, there is a centrally hypoechoic and peripherally hyperechoic structure between the common carotid artery and the jugular vein inside the carotid sheath. This structure was also identified in a fresh, nonpreserved cadaver and was marked with a hypodermic needle by means of a transdermal approach. Neck dissection was performed leaving the carotid sheath intact. B-mode imaging yielded detailed anatomic information about the structures in the carotid sheath. Further dissection showed the vagus nerve as the target of the needle. One hundred consecutive transverse carotid scans were reviewed, and the characteristic echo patterns of the vagus nerve were identified in 97 instances. A distinct and reproducible, round, hypoechoic structure was defined adjacent to the common carotid artery and jugular vein as the vagus nerve. On the basis of this study, a new, noninvasive, and highly reproducible method to locate the vagus nerve in the carotid sheath is introduced. This may lead to further clinical application such as presurgical localization or ultrasound-guided needle studies. Stimulation of the vagus nerve has been proposed for seizure therapy. The diagnosis of vagus nerve tumors may be improved.