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Three-dimensional imaging of the inner ear by volume-rendered reconstructions of magnetic resonance data
Randolf Klingebiel1, Nadine Thieme, Dietmar Kivelitz
1Neuroradiology Section, Department of Radiology, Charité CM, Schumannstr 20/21, 10098 Berlin, Germany. Randolf.Klingebiel@charite.de
Objective:
To evaluate 3-dimensional inner ear visualization by volume rendering of high-resolution magnetic resonance data in patients with clinically suspected inner ear abnormality.
Design:
Prospective comparative study of different postprocessing techniques, based on blinded film readings.
Setting:
Tertiary referral hospital.
Subjects:
Fifty patients (17 females and 33 males) aged 1 to 77 years (average age, 42 years) with sensorineural hearing loss, vertigo, and/or tinnitus.
Intervention:
Postprocessing of magnetic resonance data to inner ear reconstructions by the use of volume rendering as well as maximum-intensity projection; caloric testing by electronystagmography.
Main Outcome Measures:
Film was read blindly by 4 radiologists using a 5-point parameter scale for image quality and diagnostic value. The assessibility of inner ear subsegments was evaluated. The specificity of volume-rendered reconstructions for detecting semicircular canal obliterations was assessed in a subgroup of 9 patients by caloric testing. The time required for data postprocessing as well as film reading was recorded by means of a stopwatch.
Results:
Volume-rendered inner ear reconstructions were superior in image quality (P<.001), diagnostic value (P<.001), subsegment inner ear assessment (P<.01 to P<.001), and film reading time (P<.001) compared with maximum-intensity projections. The data postprocessing time was comparable for both techniques. Caloric weakness was noted in all patients assessed by electronystagmography.
Conclusion:
Volume rendering is the postprocessing technique of choice for 3-dimensional inner ear visualization, performing better than maximum-intensity projections with respect to various parameters.