Magnetic resonance-based volumetric measurement of the endolymphatic space in patients with Meniere's disease and other endolymphatic hydrops-related diseases

Comparing the Saccule-to-Utricle Ratio in Early- Versus Late-Stage Meniere's Disease Patients

OBJECTIVE

To compare the saccule-to-utricle ratio in early- versus late-stage Meniere's disease (MD) patients based on magnetic resonance imaging (MRI) images.

METHODS

In this retrospective study, we performed 3-dimensional real inversion recovery (3D-real IR) MRI 24 h after intratympanic gadolinium administration in unilateral MD patients at early-stage (n = 56) and late-stage (n = 70). Two radiologists independently graded endolymphatic hydrops (EH) and the saccule-to-utricle ratio inversion (SURI) was compared between the two groups. Furthermore, early-stage MD patients were further divided into two subgroups based on disease duration: ≤6 months (n = 20) and >6 months (n = 36) and the SURI was compared.

RESULTS

Among the 56 patients in the early-stage group, 26 cases (46.43%) exhibited an enlarged saccule that is larger than the utricle, showing SURI. In contrast, among the late-stage MD, only four cases (5.71%) showed SURI (p < 0.001). In the early-stage MD subgroup with a disease duration of ≤6 months, the proportion of SURI was 70% (14/20), which was higher than that in the subgroup with a disease duration of >6 months (33.33%, 12/36, p = 0.02).

CONCLUSION

SURI may serve as an effective imaging marker for diagnosis of early-stage MD. Our finding suggests that endolymphatic hydrops in MD may primarily originate from the saccule.

LEVEL OF EVIDENCE

Level 3 Laryngoscope, 2024.

Findings of Intravenous Gadolinium Inner Ear Magnetic Resonance Imaging in Patients With Acute Low-Tone Sensorineural Hearing Loss

OBJECTIVES

Acute low-tone sensorineural hearing loss (ALHL) is thought to have a different etiology from that of idiopathic sudden sensorineural hearing loss. We hypothesized that endolymphatic hydrops (EH) in the inner ear organ contributes to ALHL, even in patients without vertigo. This study investigated the presence of EH in ALHL and compared the clinical characteristics of patients with or without EH.

METHODS

We retrospectively reviewed 38 patients diagnosed with ALHL without vertigo from January 2017 to March 2022. EH was measured in all patients using inner ear magnetic resonance imaging (MRI). In addition, we selected patients who showed only mid- or high-frequency hearing loss and had available MRI data as a control group and compared the ALHL and control groups.

RESULTS

After treatment, the pure-tone average at low frequencies significantly improved compared to the initial hearing (P<0.001). Hearing recovery was observed in 63.1% of patients; however, the recovery rate did not differ based on the treatment method. During the follow-up period, six patients (15.8%) progressed to Meniere's disease, and 18 (47.4%) experienced recurrence. In the ALHL group, the cochlear hydrops ratio on the affected side (0.34±0.09) was significantly higher than on the contralateral side (0.29±0.12) (P=0.005), and most patients showed hydrops in the apex area of the cochlea. Compared with the control group (0.25±0.15), the ALHL group showed a significantly higher cochlear hydrops ratio (P=0.043). The correlation analysis showed a tendency for hearing thresholds at low frequencies to increase as the hydrops ratio increased, albeit without statistical significance.

CONCLUSION

The cochlear hydrops ratio, especially in the apex area on the affected side, was significantly higher in patients with ALHL, suggesting that EH in the cochlea contributes to the pathogenesis of ALHL.

Magnetic Resonance Volumetric Quantification of Vestibular Endolymphatic Hydrops in Patients with Unilateral Definite Meniere's Disease Using 3D Inversion Recovery with Real Reconstruction (3D-REAL-IR) Sequence

BACKGROUND

The 3D-REAL-IR MRI sequence allows for an in vivo visualization of endolymphatic hydrops. Qualitative assessment methods of the severity of vestibular and cochlear hydrops are the most commonly used.

METHODS

A quantitative volumetric measurement of vestibular EH in patients with definite unilateral Ménière's disease using the 3D-REAL-IR sequence and the calculation of the endolymphatic ratio (ELR) was intended.

RESULTS

Volumetric calculations of the vestibules, vestibular endolymph and vestibular ELR are performed in 96 patients with unilateral Ménière's disease and correlated with classic qualitative grading scales.

CONCLUSIONS

Quantitative volumetric measurement of vestibular hydrops using the 3D-REAL-IR sequence is feasible and reproducible in daily clinical practice. Vestibular ELR values exceeding 60% defined radiologically significant vestibular hydrops, while values below 30% defined radiologically non-significant vestibular hydrops.

Vestibular hydrops in patients with semicircular canal malformation

OBJECTIVE

To investigate the vestibular endolymphatic hydrops in patients with semicircular canal malformation.

METHODS

We searched 7864 patients who underwent MR Imaging after contrast injection and found 21 patients with semicircular canal malformations. Another 9 non-malformed patients with unilateral hearing loss were randomly included. We asked patients about their medical history and measured the volume of total vestibular fluid space and endolymphatic space. The vestibular volume ratio = endolymphatic space/total fluid space × 100.

RESULTS

Hearing loss was observed in 18 of 30 malformed ears and in 7 of 12 non-malformed ears. Statistical analysis showed no association between semicircular canal malformation and hearing loss. In the semicircular canal malformation group, the average vestibular volume ratio (22.6%) in the ears with hearing loss was higher than that in the ears without hearing loss (11.4%). There was no statistically significant difference in the average vestibular %EL in ears with hearing loss between the malformed inner ear group (22.6%) and non-malformed group (28.2%) (P>0.05).

CONCLUSION

There was no correlation between semicircular canal malformation and hearing loss. The mean vestibular hydrops volume ratio of the semicircular canal deformed ears with hearing loss was about 22.6%, which was not different from that of normal ears.

Development and Characteristics of Hearing Loss With the Progression of Endolymphatic Hydrops

OBJECTIVES

This study aims to explore how patients' hearing loss developed with the progression of endolymphatic hydrops and the characteristics of hearing loss at different stages.

MATERIALS AND METHODS

We collected 73 patients with definite or possible unilateral Meniere's disease or sudden hearing loss who underwent magnetic resonance imaging after intravenous contrast agent injection. There were 25 cases of isolated cochlear hydrops, 24 cases of isolated vestibular hydrops, and 24 cases of cochlear and vestibular hydrops. Primary outcome analyses included their evaluation of endolymphatic hydrops and hearing thresholds at low and high frequencies.

RESULTS

The overall hearing threshold of patients with vestibular and cochlear hydrops was significantly higher than that of patients with isolated cochlear hydrops and patients with isolated vestibular hydrops. There was a significant correlation between low-frequency hearing loss and cochlear hydrops, and the low-frequency hearing threshold was proportional to the grade of cochlear hydrops. At low frequency, the hearing threshold of patients with isolated vestibular hydrops was lower than that of patients with isolated cochlear hydrops and patients with both cochlear and vestibular hydrops. The audiogram configurations of patients with isolated cochlear hydrops consist largely of flat type and up-sloping type. The audiogram configurations of patients with isolated vestibular hydrops and patients with both cochlear and vestibular hydrops are mainly flat type and down-sloping type.

CONCLUSIONS

Patients present with low-frequency hearing loss in the early stage of endolymphatic hydrops. When the hydrops involves the whole cochlea and vestibule, the patients' hearing is impaired at both low and high frequencies.

Consensus on MR Imaging of Endolymphatic Hydrops in Patients With Suspected Hydropic Ear Disease (Meniere)

Endolymphatic hydrops (EH) is considered the histological hallmark of Meniere's disease. Visualization of EH has been achieved by special sequences of inner ear magnetic resonance imaging (MRI) with a gadolinium-based contrast agent via intravenous or intratympanic administration. Although it has been applied for more than 10 years since 2007, a unified view on this technique has not yet been achieved. This paper presents an expert consensus on MRI of endolymphatic hydrops in the following aspects: indications and contra-indications for patient selection, methods of contrast-agent administration (intravenous or intratympanic), MRI sequence selection, the specific scanning parameter settings, and standard image evaluation methods and their advantages and disadvantages. For each part of this consensus, a comment is attached to elucidate the reasons for the recommendation.

Magnetic resonance imaging of the endolymphatic space in patients with benign paroxysmal positional vertigo: volume ratio and distribution rate of the endolymphatic space

BACKGROUND

Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibular disease. It is characterised by sudden onset short lived vertigo triggered by sudden changes in head position relative to gravity.

AIMS/OBJECTIVES

We aimed to perform a quantitative volumetric analysis of the inner ear endolymphatic space in patients with BPPV.

MATERIAL AND METHODS

This study included 67 patients with BPPV and 50 control subjects (CS). The endolymphatic space/total fluid space volume ratio (%) and the distribution rate of the inner ear components in the endolymphatic space (%) were measured using three-dimensional magnetic resonance imaging.

RESULTS

Differences in the endolymphatic space/total fluid space volume ratio of the inner ear, cochlea, vestibule, and semi-circular canals (SCCs) between the CS and BPPV groups were not significant. The endolymphatic space distribution rate of the vestibule in the BPPV group was significantly lower than that in the CS group, and the endolymphatic space distribution rate of SCCs in the BPPV group was significantly higher than that in the CS group.

CONCLUSIONS AND SIGNIFICANCE

Extended endolymphatic space in patients with BPPV did not exist. The otoconia released from the damaged utricles were considered to move with the endolymphatic flow toward SCCs.

Magnetic resonance imaging of endolymphatic hydrops in patients with unilateral Meniere's disease: volume ratio and distribution rate of the endolymphatic space

BACKGROUND

Endolymphatic hydrops (ELH), which is a pathological feature of Meniere's disease (MD), is characterized by an extended endolymphatic space (ELS).

AIMS/OBJECTIVES

We aimed to perform a quantitative volumetric analysis of inner-ear ELH in patients with unilateral MD (uMD).

MATERIAL AND METHODS

This study included 97 patients with definite uMD and 49 control subjects (CS). The ELS/total fluid space (TFS) volume ratio (%) and the distribution rate of the inner-ear components in the ELS (%) were measured using 3D magnetic resonance imaging and compared between patients with uMD and CS.

RESULTS

Compared to CS, patients with uMD had significantly higher mean ELS/TFS volume ratios for inner-ear components. The mean distribution rate of the inner-ear components in the ELS was not significantly different between the two groups.

CONCLUSIONS AND SIGNIFICANCE

In patients with uMD, ELH was noted to be spread throughout the entire inner ear and the endolymph was evenly distributed in the total ELS. These findings should be useful as a standard reference for further research.

Validation of inner ear MRI in patients with Ménière's disease by comparing endolymphatic hydrops from histopathologic specimens

Intravenous gadolinium-enhanced inner-ear magnetic resonance imaging (IV-Gd inner-ear MRI) has been used to visualize endolymphatic hydrops (EH) in clinical diagnosis of Ménière's disease (MD). However, lack of histological validation has led to several concerns regarding how best to interpret the resulting images. Here, we compared hydropic changes in temporal bone specimens with the results of IV-Gd inner-ear MRI in patients with MD. Histopathologic images of temporal bones from 37 patients with MD and 10 healthy controls were collected from the National Temporal Bone Bank of the Massachusetts Eye and Ear Infirmary in the United States. The EH ratios in the vestibule and cochlea were calculated from temporal bones using the methods used for IV-Gd inner-ear MRI, and the degree to which the saccular and utricular hydrops contributed to vestibular hydrops was measured. The presence of hydropic change in each semicircular canal was assessed using temporal bone images and compared with IV-Gd inner-ear MRI scans of 74 patients with MD. Based on human temporal bone imagery, the EH ratios in the cochlea and the vestibule on the affected side were 0.314 and 0.757, respectively. In the healthy control group, the ratio was 0.064 for the cochlea and 0.289 for the vestibule; these values were significantly different from those for the affected side of MD patients. The values for the affected ear were similar to the ratios from the IV-Gd inner-ear MRI scans in MD patients. In the vestibule, saccular hydrops were more common than utricular hydrops. The average EH ratios in the saccule and utricle were 0.513 and 0.242, respectively. No significant hydropic change from each of three semicircular canals was evident in temporal bone histopathology. However, herniation of otolithic organs (saccule or utricle) into the lateral semicircular canal was found in 44.4% of the patients, with saccular herniation (24.8%) more common than utricular herniation (16.7%). Although IV-Gd inner-ear MRI might not reflect fully the results of actual histopathology due to the limited resolution of MRI and image-processing techniques, the measured EH ratios from temporal bone specimens and IV-Gd inner-ear MRI scans were similar. Hydropic change in the three semicircular canals was not significant at either the ampullated or nonampullated end. Canal invasion of vestibular hydrops seen on MRI also appeared in temporal bone histopathology, and saccular invasion was dominant.

Magnetic resonance imaging of endolymphatic hydrops in patients with unilateral Meniere's disease: a comparison between with and without herniation into the posterior and lateral semi-circular canals

BACKGROUND

The presence of endolymphatic hydrops (ELH) in patients with Meniere's disease (MD) is considered a pathological hallmark.

AIMS/OBJECTIVES

We aimed to conduct a quantitative volumetric measurement of inner ear ELH in patients with unilateral MD (uMD). The values of uMD with and without herniation into the posterior semi-circular canal (h-PSC) and the lateral semi-circular canal (h-LSC) were compared using 3 D magnetic resonance imaging.

MATERIAL AND METHODS

This study included 130 individuals (47 controls and 83 patients with uMD). We measured the total fluid space (TFS) and endolymphatic space (ELS) volumes. We also evaluated the ELS/TFS volume ratios (%).

RESULTS

The ELS/TFS volume ratios in the inner ear, cochlea, and vestibule were significantly different between the affected and contralateral sides in patients with h-PSC. Moreover, the ELS/TFS volume ratios of the inner ear, vestibule, and semi-circular canals in the affected ear were significantly higher in patients with h-PSC than in those without h-PSC. The vestibular ELS/TFS volume ratio in the affected ear was significantly higher in patients with h-LSC than in those without h-LSC.

CONCLUSIONS AND SIGNIFICANCE

H-LSC is present in extended vestibular ELH. However, this is a result of ELH progression in the inner ear.

Intravenous Delayed Gadolinium-Enhanced MR Imaging of the Endolymphatic Space: A Methodological Comparative Study

In-vivo non-invasive verification of endolymphatic hydrops (ELH) by means of intravenous delayed gadolinium (Gd) enhanced magnetic resonance imaging of the inner ear (iMRI) is rapidly developing into a standard clinical tool to investigate peripheral vestibulo-cochlear syndromes. In this context, methodological comparative studies providing standardization and comparability between labs seem even more important, but so far very few are available. One hundred eight participants [75 patients with Meniere's disease (MD; 55.2 ± 14.9 years) and 33 vestibular healthy controls (HC; 46.4 ± 15.6 years)] were examined. The aim was to understand (i) how variations in acquisition protocols influence endolymphatic space (ELS) MR-signals; (ii) how ELS quantification methods correlate to each other or clinical data; and finally, (iii) how ELS extent influences MR-signals. Diagnostics included neuro-otological assessment, video-oculography during caloric stimulation, head-impulse test, audiometry, and iMRI. Data analysis provided semi-quantitative (SQ) visual grading and automatic algorithmic quantitative segmentation of ELS area [2D, mm²] and volume [3D, mm³] using deep learning-based segmentation and volumetric local thresholding. Within the range of 0.1-0.2 mmol/kg Gd dosage and a 4 h ± 30 min time delay, SQ grading and 2D- or 3D-quantifications were independent of signal intensity (SI) and signal-to-noise ratio (SNR; FWE corrected, p < 0.05). The ELS quantification methods used were highly reproducible across raters or thresholds and correlated strongly (0.3-0.8). However, 3D-quantifications showed the least variability. Asymmetry indices and normalized ELH proved the most useful for predicting quantitative clinical data. ELH size influenced SI (cochlear basal turn p < 0.001), but not SNR. SI could not predict the presence of ELH. In conclusion, (1) Gd dosage of 0.1-0.2 mmol/kg after 4 h ± 30 min time delay suffices for ELS quantification. (2) A consensus is needed on a clinical SQ grading classification including a standardized level of evaluation reconstructed to anatomical fixpoints. (3) 3D-quantification methods of the ELS are best suited for correlations with clinical variables and should include both ears and ELS values reported relative or normalized to size. (4) The presence of ELH increases signal intensity in the basal cochlear turn weakly, but cannot predict the presence of ELH.

The Importance of the Temporal Bone 3T MR Imaging in the Diagnosis of Menière's Disease

BACKGROUND

The aim of this study was to evaluate endolymphatic hydrops using the 3T temporal bone magnetic resonance imaging (MRI), performed according to the chosen protocol, and determine whether it could be applied as an objective diagnostic tool for Menière's disease.

METHODS

105 participants diagnosed with probable (n = 50) and definite (n = 55) Menière's disease were included in this prospective study at Vilnius University Hospital, Santaros Clinics. Audiometry, vestibular function tests, videonystagmography, and computer posturography were performed before MRI. The 3T MRI with gadolinium contrast was performed to evaluate the endolymphatic hydrops. Imaging protocol consisted of 3D-FLAIR and 3D T2DRIVE sequences. Vestibular endolymphatic sac was interpreted as enlarged if occupied more than 50% of the vestibular area.

RESULTS

78.1% of subjects had abnormal MRI findings other than hydrops, and it was more than 90% (50/55) of patients in the definite MD group (p < 0.001). Changes in caloric test were observed in 63.8% of subjects in general, and in 76.4% of patients with a definite Menière's disease. The side of the endolymphatic hydrops observed on MR imaging corresponded to the clinical diagnosis of the Menière's disease based on the results of audiometry (p < 0.001) and unilateral weakness (p < 0.001). Endolymphatic hydrops on MRI and directional preponderance in caloric test were two independent predictors of the definite Menière's disease.

CONCLUSIONS

Temporal bone 3T MRI with gadolinium contrast is clinically superior to confirm the diagnosis of Menière's disease. Grade II endolymphatic hydrops on MRI, directional preponderance, and unilateral weakness on caloric test were independent predictors for the definite Menière's disease.

Deep learning for the fully automated segmentation of the inner ear on MRI

Segmentation of anatomical structures is valuable in a variety of tasks, including 3D visualization, surgical planning, and quantitative image analysis. Manual segmentation is time-consuming and deals with intra and inter-observer variability. To develop a deep-learning approach for the fully automated segmentation of the inner ear in MRI, a 3D U-net was trained on 944 MRI scans with manually segmented inner ears as reference standard. The model was validated on an independent, multicentric dataset consisting of 177 MRI scans from three different centers. The model was also evaluated on a clinical validation set containing eight MRI scans with severe changes in the morphology of the labyrinth. The 3D U-net model showed precise Dice Similarity Coefficient scores (mean DSC-0.8790) with a high True Positive Rate (91.5%) and low False Discovery Rate and False Negative Rates (14.8% and 8.49% respectively) across images from three different centers. The model proved to perform well with a DSC of 0.8768 on the clinical validation dataset. The proposed auto-segmentation model is equivalent to human readers and is a reliable, consistent, and efficient method for inner ear segmentation, which can be used in a variety of clinical applications such as surgical planning and quantitative image analysis.

Magnetic resonance imaging of endolymphatic space in patients with sensorineural hearing loss: comparison between fluctuating and idiopathic sudden sensorineural hearing loss

Background: Recently, 3-Tesla magnetic resonance imaging (MRI) after an intravenous gadolinium injection has been used to describe the endolymphatic space (ELS).Objectives: This study described the histopathological differences between idiopathic sudden sensorineural hearing loss (ISSNHL) and fluctuating sensorineural hearing loss (FSNHL) by examining the ELS. Additionally, the relationship between the affected cochlear and vestibular ELS/total fluid space (TFS) volume ratio and the duration from the onset to MRI in patients with FSNHL were evaluated.Material and methods: This study included 205 individuals without vertigo: 47 controls, 94 with ISSNHL, and 64 with FSNHL. The TFS and ELS volumes were measured and the ELS/TFS volume ratios (%) were evaluated.Results: The cochlear and vestibular ELS/TFS volume ratios of the affected ear in patients with FSNHL were significantly higher than that in those with ISSNHL. There was no correlation between the duration from FSNHL onset to the MRI scan in the affected cochlea and vestibule.Conclusion and significance: There were differences in the form of hearing fluctuation and the extended ELS volume between ISSNHL and FSNHL. ISSNHL cases with severe ELS extension were likely to change to FSNHL.

Audiological Findings in Patients with Vestibular Migraine and Migraine: History of Migraine May Be a Cause of Low-Tone Sudden Sensorineural Hearing Loss

INTRODUCTION

The aim of this study was to investigate and compare the auditory findings in migraine, vestibular migraine (VM), and healthy controls.

METHODS

Twenty-eight migraine patients (56 ears), 18 VM (36 ears), and 25 healthy controls (50 ears) were included. Audiometry, speech discrimination scores, distortion product optoacoustic emission (DPOAE), and auditory brainstem response were tested.

RESULTS

The pure tone in the VM group showed higher thresholds at lower frequencies (250, 500, 1,000, 2,000 Hz) than the control group, with statistical differences observed (P250 Hz = 0.001, P500 Hz = 0.003, P1,000 Hz = 0.016, P2,000 Hz = 0.002). Compared with the healthy controls, the patients with VM had significantly lower amplitudes of DPOAE at 1 kHz (p < 0.001) and 2 kHz (p = 0.020), and the patients with migraine had lower amplitudes at 2 kHz (p = 0.042). Compared with the control group, the patients with migraine reported prolonged latency of wave V (p = 0.016) and IPL I-V (p = 0.003). The patients with VM had significant prolongation of IPL I-V (p = 0.024).

CONCLUSION

Not only the peripheral, but also the central auditory system was involved in patients with migraine and VM. In particular, lower frequencies of the auditory system were more likely to be involved in VM. The history of migraine may be a cause of low-tone sudden sensorineural hearing loss.