[Changes in the blood-labyrinth barrier. Assessments by magnetic resonance].
OBJECTIVE
Recent progress in magnetic resonance imaging (MRI), with contrast-enhanced and steady-state sequences, allows fine depiction of labyrinth abnormalities related to neoplastic, inflammatory, ischemic, degenerative or traumatic disorders. We examined 488 patients with sensorineural hearing loss, vertigo or dizziness, but normal CT findings, to evaluate MR capabilities in showing labyrinth conditions.


METHODS
January 1994 to May 1998, four hundred and eighty-eight patients with labyrinthine symptoms were submitted to CT. Sixty-eight of them, with normal CT findings, were also examined with MRI, which was performed using quadrature head or surface coils and a single dose (0.1 mmol/kg) Gd-DTPA administration. Conventional T1 and T2 high resolution SE images were acquired. The labyrinth was studied of 52 patients with normal CT findings and no abnormalities in the cerebello-pontine angle or internal auditory canal.


RESULTS
Fourteen of 52 patients (27%) exhibited labyrinth enhancement from tumor (5%), hemorrhage (3%), infection (15%), surgical (2%) or radiosurgical (2%) procedures. GRASS sequences allowed differentiation of mass lesions (e.g., tumors, clots) from other conditions.


CONCLUSIONS
Generally the labyrinth exhibits no contrast enhancement even after a triple Gd-DTPA dose. In inflammatory conditions, enhancement is not always diffuse, as expected, but may be focal. Spontaneous hemorrhages can account for labyrinth enhancement. In neoplastic conditions, enhancement may persist for as many as 6 months, and a mass effect against labyrinthine fluids may appear on GRASS images. Although there are no reports on labyrinthine degeneration after radiation therapy, one of our patients submitted to irradiation 7 years previously, had focal bilateral cochlear enhancement, which suggested a correlation with previous treatment.
Manfrè
L
L
Istituto di Radiologia P. Cignolini, Università, Palermo. lgmanfre@tin.it
Bencivinni
F
F
Caronia
A
A
Angileri
T
T
Manasia
G
G
De Maria
M
M
D002199:Capillary Permeability; D003287:Contrast Media; D007758:Ear, Inner / Q000098:blood supply* / Q000473:pathology; D019786:Gadolinium DTPA; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D012680:Sensitivity and Specificity; D014012:Tinnitus / Q000175:diagnosis; D014717:Vertigo / Q000175:diagnosis
D003287:Contrast Media; D019786:Gadolinium DTPA