Does CISS MRI Reliably Depict the Endolymphatic Duct in Children with and without Vestibular Aqueduct Enlargement?

Olutayo I. Olubiyi; Nicholas Thompson; Thad Benefield; Kassie L. McCullagh; Benjamin Y. Huang

doi:10.3174/ajnr.A8158

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FIG 1.
Flow chart summarizing identification, selection, and exclusion of subjects from this study.
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FIG 2.
Examples of the 3 types of ELD visibility observed on MR imaging. Upper row, Representative axial-view non-contrast-enhanced temporal bone CT images of 3 different ears from different patients. Lower row, Axial temporal bone CISS MR images corresponding to the same ears as the CT images directly above demonstrate type 1 (lower left image), type 2 (lower middle image), and type 3 ELDs (lower right image). Blue arrows in the upper row indicate the vestibular aqueducts; red arrows in the lower row indicate the visible ELDs.
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FIG 3.
CISS MR images demonstrating additional examples of type 2 (faintly visible) ELDs (arrows) in 3 different patients: A, A 4-year-old girl with mild SNHL in the left ear. This patient demonstrated EVA on CT. B, A 1-year-old boy with profound SNHL in the right ear. This patient did not have VA enlargement on CT. C, An 8-year-old girl with profound SNHL in the left ear. This patient did not have VA enlargement on CT.
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FIG 4.
CISS MR images demonstrating additional examples of type 3 (easily visible) ELDs (arrows) in 3 different patients. A, A 7-month-old girl with severe SNHL in the right ear. B, A 6-year-old boy with severe SNHL in the right ear. C, A 4-year-old girl with mild SNHL in the left ear. All patients in these images demonstrated EVA on CT.

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Table 1:

Baseline demographic, audiometric, and imaging data

Patient-Level Characteristics	Overall (n = 98 Patients)
Demographic
Age (mean) (SD) (yr)	6.2 (4.7)
Female sex (No.) (%)	53 (54.1)
Hearing loss laterality (No.) (%)
Bilateral	66 (67.3)
Unilateral	31 (31.6)
Data not available	1 (1.0)
MR imaging field strength (No.) (%)
1.5T (%)	38 (38.8)
3T (%)	60 (61.2)

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Table 2:

Baseline demographic, audiometric, and imaging data

Characteristics by Evaluated Ears	Overall (n = 196 Ears)
Type of hearing loss (No.) (%)
Normal	31 (15.8)
Sensorineural	140 (71.4)
Conductive	18 (9.2)
Mixed	5 (2.5)
Audiometry data not available	2 (1)
Severity of hearing loss (No.) (%)
Normal	31 (15.8)
Mild	15 (7.7)
Moderate	23 (11.7)
Severe	42 (21.4)
Profound	83 (42.3)
Audiometry data not available	2 (1)
ELD visualization (No.) (%)
Type 1	145 (74.0)
Type 2	29 (14.8)
Type 3	22 (11.2)

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Table 3:

ELD visibility on high-resolution MR imaging based on EVA status

VA Status on CT^{^a}	Type of ELD Visualization on MR Imaging			Totals (Column %)
VA Status on CT^{^a}	Type 1, Not Visualized No. (Row %)	Type 2, Faintly Visualized No. (Row %)	Type 3, Easily Visualized No. (Row %)	Totals (Column %)
EVA –	136 (87.2)	20 (12.8)	0 (0)	156 (79.6)
EVA +	9 (22.5)	9 (22.5)	22 (55.0)	40 (20.4)
Totals (row %)	145 (74.0)	29 (14.8)	22 (11.2)	196 (100)

↵a There was evidence of an association between VA status and ELD visibility (P < .0008).

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Table 4:
Predicted probability of VA enlargement based on the type of MR Imaging visibility
Type of ELD Visualization on High-Resolution MR Imaging Predicted Probability of EVA 95% Confidence Level
Type 1 0.053 (0.024–0.114)
Type 2 0.288 (0.141–0.498)
Type 3 0.997 (0.194–0.999)

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Table 5:

Predicted mean VA width based on MR imaging visibility of the ELD^{^a}

Type of ELD Visualization on High-Resolution MR Imaging	VA Midpoint Width (Axial Plane)		VA Opercular Width (Axial Plane)		VA Midpoint Width (Pöschl Plane)
Type of ELD Visualization on High-Resolution MR Imaging	Predicted Mean (mm)	95% CI	Predicted Mean (mm)	95% CI	Predicted Mean (mm)	95% CI
Type 1	0.62	(0.55–0.69)	0.92	(0.80–1.03)	0.59	(0.53–0.64)
Type 2	0.97	(0.83–1.11)	1.43	(1.20–1.67)	0.83	(0.72–0.94)
Type 3	2.08	(1.92–2.25)	3.00	(2.73–3.28)	1.98	(1.85–2.11)

↵a All predicted means differed significantly from each other. For comparison of predicted mean VA opercular width between type 1 and type 2 ears, Tukey-adjusted P = .0004. For comparison of predicted mean VA midpoint width in the Pöschl plane between type 1 and type 2 ears, P = .0005. For all other comparisons, P < .0001.

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Table 6:

Results of 3-outcome ELD assessment on MR imaging by the 3 readers

Type of ELD Visualization on High-Resolution MR Imaging	Reader 1 (Fellow and Senior Radiologist)		Reader 2 (Junior Radiologist)		Reader 3 (Neurotologist)
Type of ELD Visualization on High-Resolution MR Imaging	Right	Left	Right	Left	Right	Left
Type 1	69	76	49	47	67	73
Type 2	17	12	34	38	20	16
Type 1 or 2	86	88	83	85	87	89
Type 3	12	10	15	13	11	9

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Table 7:

Summary of interreader agreement analysis for ELD visibility on MR imaging

Readers	3-Category Outcome: Fleiss κ (95% CI)		2-Category Outcome: Fleiss κ (95% CI)
Readers	Right	Left	Right	Left
All 3 readers	0.691 (0.579–0.803)	0.531 (0.396–0.666)	0.849 (0.714–0.984)	0.825 (0.667–0.982)
Pair-wise comparisons:
Reader 1 vs 2	0.555 (0.402–0.709)	0.361 (0.186–0.537)	0.785 (0.604–0.966)	0.754 (0.547–0.960)
Reader 1 vs 3	0.935 (0.863–1.007)	0.844 (0.724–0.963)	0.951 (0.885–1.047)	0.942 (0.828–1.055)
Reader 2 vs 3	0.615 (0.468–0.762)	0.449 (0.279–0.619)	0.822 (0.654–0.991)	0.795 (0.601–0.989)