Magnetic resonance imaging of guinea pig cochlea after vasopressin-induced or surgically induced endolymphatic hydrops
Received 3 June 2009; received in revised form 1 October 2009; accepted 2 October 2009.
Abstract
Objective
To investigate the ability to detect the in vivo cochlear changes associated with vasopressin-induced and surgically induced endolymphatic hydrops using MRI at 3 tesla (T).
Study Design
Prospective, animal model.
Setting
Animal laboratory.
Subjects and Methods
In group 1, five guinea pigs underwent post–gadolinium temporal bone MRI before and after seven and 14 days of chronic systemic administration of vasopressin by osmotic pump. In group 2, five guinea pigs underwent temporal bone MRI eight weeks after unilateral surgical ablation of the endolymphatic sac. Three-tesla high-resolution T1-weighted sequences were acquired pre- and postcontrast administration. Region of interest signal intensities of the perilymph and endolymph were analyzed manually. Quantitative evaluation of hydrops was measured histologically.
Results
Gadolinium preferentially concentrated in the perilymph, allowing for distinction of cochlear compartments on 3.0-T MRI. The T1-weighted contrast MRI of vasopressin-induced hydropic cochlea showed significant increases in signal intensity of the endolymph and perilymph. Surgically induced unilateral hydropic cochlea also showed increased signal intensity, compared with the control cochlea of the same animal, but less of an increase than the vasopressin group. The histological degree of hydrops induced in the vasopressin group was comparable to previous studies.
Conclusions
In vivo postcontrast MRI of the inner ear demonstrated cochlear changes associated with chronic systemic administration of vasopressin and surgical ablation of the endolymphatic sac. Understanding the MRI appearance of endolymphatic hydrops induced by various methods contributes to the future use of MRI as a possible tool in the diagnosis and treatment of Ménière's disease.
aDepartment of Otolaryngology–Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, NC
bDepartment of Radiology, University of North Carolina School of Medicine, Chapel Hill, NC
Corresponding author: Allen F. Marshall, MD, CB# 7070, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7070
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
ABSTRACT