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Screening protocol for MR imaging of the internal auditory canal
A W Litt1, P Mirsky, B D Berson
1Department of Radiology, New York University Medical Center, NY 10016.
Journal of Computer Assisted Tomography
|November 1, 1991
Summary
A new MRI protocol using 5 mm axial T1-weighted images with a coronal scout is effective for screening internal auditory canal and cerebellopontine angle diseases. This faster method eliminates the need for 3 mm slices in most patients with sensorineural hearing loss.
Area of Science:
- Radiology
- Neuroimaging
- Magnetic Resonance Imaging
Background:
- Previous MRI protocols for internal auditory canal (IAC) and cerebellopontine angle (CPA) disease screening required 5 mm axial T1-weighted images post-Gd-DTPA, with 3 mm slices needed in 20% of cases.
- This necessitated additional scanning time and resources.
Purpose of the Study:
- To develop and evaluate a modified, more efficient MRI protocol for screening IAC and CPA diseases.
- To reduce the number of patients requiring additional 3 mm slice imaging.
Main Methods:
- A new three-sequence protocol was implemented: coronal T1-weighted scout, 5 mm axial T1-weighted images angled through the IACs post-Gd-DTPA, and routine axial T2-weighted images of the posterior fossa.
- One hundred eleven patients with sensorineural hearing loss were studied using this protocol.
Main Results:
- The modified protocol successfully diagnosed IAC and CPA disease in 109 out of 111 patients using only the 5 mm axial T1-weighted images.
- In the remaining two cases, coronal images confirmed the diagnosis suspected on axial views.
- Three millimeter slices were not required for any patient.
Conclusions:
- The revised three-sequence, post-Gd-DTPA MRI protocol is highly effective for screening IAC and CPA diseases.
- This 12-minute scan protocol significantly improves efficiency by eliminating the need for 3 mm slices in most cases.