Gadolinium distribution in cochlear perilymph: differences between intratympanic and intravenous gadolinium injection

Blood-labyrinth barrier breakdown in Meniere's disease

OBJECTIVE

We compared the signal intensity ratio (SIR) of the cochlear basal turn between Meniere's disease and healthy controls to investigate potential damage of the blood-labyrinth barrier in Meniere's disease.

METHODS

Thirty patients diagnosed with unilateral definite Meniere's disease and 24 healthy controls were enrolled. 3D-FLAIR scan was conducted to assess the grades of endolymphatic hydrops in Meniere's patients while measuring the SIR of cochlear basal turns in both groups. The differences of bilateral SIR between Meniere's disease and healthy control were compared, and the correlation between the SIR on affected ear in Meniere's disease and the grades of cochlear and vestibular hydrops were analyzed.

RESULTS

SIR of affected ear in Meniere's disease exhibited significant increase compared to that of unaffected ear. No significant difference was observed in SIR between the two ears in the healthy control. Furthermore, the SIR of unaffected side in Meniere's disease was higher than that of both ears in healthy controls. The SIR in affected ear of Meniere's disease exhibited positive correlation with hydrops in both cochlea and vestibula.

CONCLUSION

The permeability of blood-labyrinth barrier is increased in Meniere's disease, in combination with the typical criteria of Meniere's disease it may be a good biological marker. Destruction of blood-labyrinth barrier may be one of the causes of endolymphatic hydrops in Meniere's disease.

The effect of delay time after injecting gadobutrol on the diagnosis of endolymphatic hydrops

OBJECTIVES

The aim of this study was to reduce the time delay between gadolinium injection and 3D-FLAIR (three-dimensional fluid-attenuated inversion recovery) MRI by using a single dose of intravenous gadobutrol in Menière's disease patients.

METHODS

17 patients diagnosed with definite unilateral Meniere's disease underwent 3D-FLAIR MRI scans at 2, 4, and 6 h post-intravenous administration of a single-dose of gadobutrol. The signal intensity ratio of bilateral inner ear, cochlear and vestibular hydrops was measured at 2 h, 4 h and 6 h, while the differences in signal intensity ratio and endolymphatic hydrops were evaluated at three time points.

RESULTS

The cochlea, vestibule, and semicircular canal exhibit clear structural features with distinct perilymph-endolymph boundaries at 2 h, 4 h, and 6 h. The signal intensity ratio of the affected ear was significantly higher than that of the unaffected ear at 2 h, 4 h, and 6 h. The signal intensity ratio at 4 h and 6 h in both the affected and unaffected ears was significantly higher than that at 2 h, but there was no significant difference between 4 h and 6 h. Cochlear hydrops and vestibular hydrops show no significant differences at these time points, demonstrating excellent consistency.

CONCLUSIONS

We have demonstrated that 3D-FLAIR images acquired 2 h after intravenous administration of a single-dose gadobutrol are of high quality and equally effective as those obtained at the conventional 4-h time point for diagnosing endolymphatic hydrops in Menière's disease. In clinical practice, the delay time can be safely shortened to 2 h.

The use of cochlear-enhancement imaging to predict hearing preservation following vestibular schwannoma removal

BACKGROUND

Hearing preservation is challenging for patients after the removal of large vestibular schwannomas (VSs). Here, using preoperative magnetic resonance (MR) imaging, we investigated the significance of cochlear enhancement (CE) for predicting postoperative hearing preservation.

METHODS

Between January 2014 and December 2019, 34 VS-patients with serviceable hearing underwent tumor-removal surgery using a retrosigmoid approach. The presence or absence of CE using both T2-weighted and gadolinium-enhanced T1-weighted MR images was assessed in VS patients using the pixel-analysis method. Segmented volumetric analyses were also performed using GrowCut 3D slicer software.

RESULTS

There were 17 patients (50%) without CE and 17 (50%) with CE. Ten of the 17 non-CE patients (58.8%) had postoperative hearing preservation. In contrast, only 3 of the 17 patients with CE (17.6%) had postoperative hearing preservation. There were no significant tumor-characteristic differences between the two groups. The presence of CE on both the T2-weighted and the gadolinium-enhanced T1-weighted MR images correlated significantly with postoperative hearing outcomes (P=0.032). Only pure-tone averages were significantly different between the two groups (P=0.049).

CONCLUSIONS

Preoperative serviceable hearing is likely to be preserved after surgery in non-CE VS patients. Preoperative CE assessment using MR imaging may be a useful predictor for postoperative hearing outcomes in VS patients.

Correlation Between Quantitative Value of Endolymphatic Hydrops and Hearing Threshold Using Magnetic Resonance Imaging

OBJECTIVES

This study investigated the relationship between quantitative value of endolymphatic hydrops in the affected ear and the hearing threshold in patients with unilateral Meniere's disease.

STUDY DESIGN

Prospective study.

METHODS

Forty patients with unilateral definite Meniere's disease were diagnosed in outpatient clinic. We recorded their clinical symptoms (duration of vertigo and tinnitus and duration of vertigo attacks), and obtained the hearing thresholds of high, middle, and low by pure tone audiometry. A 3D-FLAIR MRI revealed endolymphatic hydrops and assessed quantitative values of cochlear and vestibular endolymphatic hydrops. We assessed the correlation between hearing thresholds and quantitative values of endolymphatic hydrops.

RESULTS

All patients showed varying degrees of endolymphatic hydrops in the affected ear. With the duration of vertigo, tinnitus and vertigo attacks as control variables, partial correlation analysis showed that the correlation coefficients between quantitative value of cochlear hydrops and hearing thresholds of low, middle, and high tone in the affected ear were 0.581, 0.610, and 0.125, respectively. The correlation coefficients between quantitative value of vestibular hydrops and hearing thresholds of low, middle, and high tone in the affected ear were 0.727, 0.569, and 0.201, respectively.

CONCLUSIONS

The degree of endolymphatic hydrops in Meniere's disease can be revealed and assessed by 3D-FLAIR MRI after intravenous administration of double doses of gadoterate meglumine. Clinical evaluation of endolymphatic hydrops in Meniere's disease can be assisted by low- and middle-tone hearing thresholds, thereby providing anatomical support for the clinical symptoms of Meniere's disease.

Application of inner ear MRI after intravenous gadolinium injection in SSNHL

BACKGROUND

With the development of inner ear gadolinium imaging technology, its clinical application is more and more frequent.

OBJECTIVES

To explore the application value of inner ear MRI after intravenous gadolinium injection in sudden sensorineural hearing loss.

MATERIAL AND METHODS

The clinical data of 28 patients who were preliminarily diagnosed with sudden sensorineural hearing loss and the results of intravenous gadolinium MRI examination were analyzed to find the relationship between them.

RESULTS

Of the 28 patients (30 ears) with idiopathic sudden sensorineural hearing loss, 20 (71.4%) showed normal MRI. MRI abnormalities related to hearing loss were found in 8 cases (28.6%), of which 5 cases (17.9%) showed hydrops in the inner ear membrane labyrinth, 2 cases (7.1%) showed mastoiditis on the affected side, and 1 case (3.6%) showed vestibular schwannoma.

CONCLUSIONS AND SIGNIFICANCE

Inner ear MRI after intravenous gadolinium injection can be used as an index to detect the cause of sudden deafness, one of the factors to guide clinical treatment, and an important means to further explore the relationship between hydrops of membranous labyrinth and SSNHL.

Clinical application of MIIRMR as a salvage method in gadolinium-enhanced MRI after intra-tympanic injection

BACKGROUND

Three-dimensional fluid-attenuated inversion-recovery (3 D-FLAIR) and real inversion-recovery (3 D-real IR) sequences are used to detect endolymphatic hydrops (EH), but medium inversion-time inversion-recovery imaging with magnitude reconstruction (MIIRMR) may be more sensitive.

AIMS

We investigated the inner-ear visualisation success rate and EH detection rates of 3 D-FLAIR and 3 D-real IR, and whether salvage MIIRMR could improve EH detection.

MATERIALS AND METHODS

Fifty-one patients (102 ears) with episodic or chronic vestibular syndrome were injected intra-tympanically with 8-fold diluted gadolinium, and 3 D-FLAIR and 3 D-real IR images obtained 24-h post-injection. If 3 D-FLAIR inner-ear visualisation failed, additional MIIRMR was performed. The success and EH detection rate increase by MIIRMR was calculated. The diagnostic performance of combined MIIRMR + 3D-FLAIR + 3D-real IR for Meniere's disease (MD) was evaluated.

RESULTS

The success rates of 3 D-FLAIR and 3 D-real IR were 88.90% and 72.55%, respectively. MIIRMR increased the success and EH detection rates by 11.10% and 6.86%, respectively. In MD, MIIRMR increased these rates by 10.53% and 10.53%, respectively. 3 D-FLAIR + 3D-real IR + MIIRMR had 92.11% sensitivity, 79.68% specificity, 72.92% positive-predictive value, and 94.44% negative-predictive value for MD diagnosis.

CONCLUSION AND SIGNIFICANCE

MIIRMR can improve success and EH detection rates when 3 D-FLAIR fails. Combined MIIRMR + 3D-FLAIR + 3D-real IR is more valuable for diagnosing MD than conventional sequences.

Optimal sequences and sequence parameters for GBCA-enhanced MRI of the glymphatic system: a systematic literature review

BACKGROUND

The glymphatic system (GS) is a recently discovered waste clearance system in the brain.

PURPOSE

To evaluate the most promising magnetic resonance imaging (MRI) sequence(s) and the most optimal sequence parameters for glymphatic MRI (gMRI) 4-24 h after administration of gadolinium-based contrast agent (GBCA).

MATERIAL AND METHODS

Multiple literature databases were systematically searched for articles regarding gMRI or MRI of the perilymph in the inner ear until 11 May 2020. All relevant MRI sequence parameters were tabulated for qualitative analysis. Their potential was assessed based on detection of low dose GBCA, primarily measured as signal intensity (SI) ratio.

RESULTS

Thirty articles were included in the analysis. Three-dimensional fluid attenuated inversion recovery (3D-FLAIR), 3D Real Inversion Recovery (3D-Real IR), and multiple 3D T1-weighted gradient echo sequences were used. In perilymph, 3D-FLAIR with a TE of at least 400 ms yielded the highest SIRs. In the qualitative analysis of inner ear studies using 3D-FLAIR, TR was in the range of 4400-10,000 ms, TI 1500-2600 ms, refocusing flip angle (rFA) (range 120°-180°), and echo train length (ETL) 23-173. In the gMRI studies, quantitative analysis was not possible. In the qualitative analysis, 3D-FLAIR was used in the majority (8/12) of the studies, usually with TR 4800-9000 ms, TI 1650-2500 ms, TE 311-561 ms, rFA 90°-120°, and ETL 167-278.

CONCLUSION

Long TE 3D-FLAIR is the most promising sequence for detection of low-dose GBCA in the GS. Clinical and/or phantom studies on other MRI parameters are needed for further optimization of gMRI.

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.

Comparison of inner ear MRI enhancement in patients with Meniere's disease after intravenous injection of gadobutrol, gadoterate meglumine, or gadodiamide

PURPOSE

To compare the enhancement results of three gadolinium contrast agents in the inner ear of patients with Meniere's disease 4 h after intravenous injection of gadobutrol, gadoterate meglumine, or gadodiamide.

METHODS

We enrolled 60 patients with a definitive diagnosis of unilateral Meniere's disease and divided them into three groups of 20 patients; each group received a double dose of gadobutrol, gadoterate meglumine, or gadodiamide. The postcontrast signal intensity of the basal cochlear turn was scored quantitatively, and qualitative visual evaluation of the cochlea, vestibule and semi-circular canals was also performed. The results of both evaluations were compared between the three patient groups.

RESULTS

The cochlear basal turn signal intensity of the gadobutrol group was significantly higher than that of the gadoterate meglumine and gadodiamide groups; however, no significant difference was observed between the gadoterate meglumine and gadodiamide groups. The intensity of visualization of the semi-circular canals was significantly better in the bilateral gadobutrol group than in the gadoterate meglumine and gadodiamide groups; however, there was no significant difference in terms of the intensity of visualization of the semi-circular canals between the gadoterate meglumine and gadodiamide groups. There were no significant differences in the intensity of visualization of the cochlea and vestibule among the three groups.

CONCLUSIONS

Compared with gadoterate meglumine and gadodiamide, gadobutrol can provide a higher degree of perilymphatic enhancement and better anatomical details of the semi-circular canals in the ears of patients with Meniere's disease.

Differential Diagnosis of Endolymphatic Hydrops Between "Probable" and "Definite" Ménière's Disease via Magnetic Resonance Imaging

OBJECTIVES

To investigate the grade of endolymphatic hydrops in patients with "probable" and "definite" Ménière's disease via magnetic resonance imaging (MRI) and to determine whether MRI could assist clinicians in differential diagnosis between probable and definite Ménière's disease.

STUDY DESIGN

Prospective study.

SETTING

Three-dimensional FLAIR MRI (fluid-attenuated inversion recovery) to examine endolymphatic hydrops in Ménière's disease.

METHODS

A total of 51 patients diagnosed with probable (n = 20) or definite (n = 31) unilateral Ménière's disease were enrolled. Three-dimensional FLAIR MRI was performed to evaluate the grade of endolymphatic hydrops. The differences in endolymphatic hydrops between the probable and definite groups were analyzed.

RESULTS

The grade of endolymphatic hydrops was more severe in the definite group than in the probable group (P < .05).

CONCLUSION

MRI revealed a higher grade of endolymphatic hydrops in patients with definite Ménière's disease than in patients with probable Ménière's disease. As a result, it may be clinically useful and an effective tool in the differentiation between definite and probable Ménière's disease.

The Correlation Between Endolymphatic Hydrops and Clinical Features of Meniere Disease

OBJECTIVES

The purpose of this study was to investigate the grades of endolymphatic hydrops determined by gadolinium-contrast magnetic resonance (MR) and correlation to the clinical features in patients with Meniere disease.

STUDY DESIGN

Prospective study.

METHODS

A total of 24 patients suffering from unilateral Meniere disease with either definite or probable clinical diagnosis were included. The duration of vertigo, duration of tinnitus, duration of vertigo attacks, hearing thresholds, and canal paresis (CP) value of caloric tests were assessed. Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (MRI) was performed 4 hours after intravenous injection of double dose of gadobutrol (Gd) to show endolymph and perilymph, and the grades of endolymphatic hydrops were measured. Additionally, the correlation between clinical features and the grades of endolymphatic hydrops of cochlea and vestibular were evaluated.

RESULTS

Different grades of the endolymphatic hydrops in the impaired ear were revealed by MRI. The Spearman correlation showed a strong correlation between the hearing thresholds of low, middle, and high tone and the grades of cochlea and vestibular hydrops (P < .05); However, no significant correlation between the duration of vertigo, duration of tinnitus, duration of vertigo attacks, CP value, and endolymphatic hydrops was determined (P > .05).

CONCLUSION

By visualizing the endolymph and perilymph of inner ear in patients with Meniere disease assisted with intravenous injection of double doses of Gd, the grades of endolymphatic hydrops could be assessed. As a result, the grades of endolymphatic hydrops in patients with Meniere disease can be used to predict the level of hearing impairment.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E144-E150, 2021.

3D-real IR MRI of Meniere's disease with partial endolymphatic hydrops

OBJECTIVES

A three-dimensional inversion-recovery sequence with real reconstruction (3D-real IR) sequence 4 h after intravenous gadolinium injection (IV) has been used to visualize the endolymphatic hydrops (ELH) in Meniere's disease (MD). This study was designed to explore the pathology of MD with partial ELH.

METHODS

We collected 338 patients with definite MD, all of whom underwent the IV method. Patients who were found to have partial ELH (vestibular or cochlear) were enrolled. The hearing thresholds of the enrolled patients were analyzed, the regions of interest of the cochlear perilymph and the cerebellum white matter were determined, and the signal intensity ratio in the former to the latter (CC ratio) for both sides in the patients was subsequently evaluated.

RESULTS

Of the 338 collected patients with definite MD, 19 patients (5.6%) had unilateral vestibular ELH (N = 18) or cochlear ELH (N = 1), and 4 patients (1.2%) with bilateral ELH had contralateral cochlear ELH. The CC ratio of the affected side (1.44 ± 0.46) was higher than that of the unaffected side (1.15 ± 0.33, P < 0.05) in the 19 patients with unilateral ELH. Conversely, there was no difference between the ratio of the contralateral side (1.18 ± 0.16) and the unaffected side (P > 0.05) in the 4 patients with bilateral ELH.

CONCLUSIONS

Partial vestibular ELH was more common than partial cochlear ELH in MD. Moreover, vestibular ELH, rather than cochlear ELH, may correlate with the elevated contrast effect in the affected side, which may better reflect the pathologic mechanism of MD.

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

OBJECTIVE

To employ magnetic resonance imaging (MRI) to measure the volume of the inner ear endolymphatic space (ELS) in patients with acute low-tone sensorineural hearing loss (ALHL), sudden deafness (SD), cochlear Meniere's disease (cMD), and unilateral MD (uMD) compared with control subjects (CS) with chronic rhinosinusitis.

METHODS

Forty-one patients with ALHL, 82 with SD, 48 with cMD, 72 with uMD, and 47 CS participated in the study. With the exception of all uMD patients, none of the subjects had vertigo. Images of the inner ear fluid space, positive perilymph signal, and positive endolymph signal were acquired using a 3-T MRI scanner. Three-dimensional images were reconstructed semi-automatically by using anatomical and tissue information to fuse the inner ear fluid space images and the ELS images.

RESULTS

The cochlear ELS/total fluid space (TFS) volume ratio was 10.2±6.7% (mean±standard deviation) in the CS group, 12.1±5.7% in ALHL patients, 15.2±8.7% in SD patients, 18.1±8.2% in cMD patients, and 21.9±16.4% in uMD patients. The vestibular ELS/TFS volume ratio was 17.7±10.2% in the CS group, 18.9±8.3% in ALHL patients, 19.9±11.3% in SD patients, 22.5±13.7% in cMD patients, and 35.7±24.1% in uMD patients. The cochlear ELS/TFS volume ratio in patients with uMD was similar to that in the cMD group and significantly higher than that in the CS, ALHL, and SD groups (CS=ALHL<SD<cMD=uMD: p<0.05 for CS vs. SD and p<0.01 for CS vs. cMD). The vestibular ELS/TFS volume ratio in patients with uMD was significantly higher than that in the CS and all other patient groups (CS=ALHL=SD=cMD<uMD: p<0.01 for uMD vs. all other groups).

CONCLUSION

The cochlear ELS volume of patients with MD and other endolymphatic hydrops-related diseases differed from that of CS. Our results suggest that ALHL may not be caused by endolymphatic hydrops. We confirmed the presence of extended ELS in patients with SD.

Magnetic Resonance Imaging of Ménière's Disease After Intravenous Administration of Gadolinium

OBJECTIVES

A three-dimensional (3D) inversion-recovery (IR) sequence with real reconstruction (3D-real IR) sequence 4 hours after intravenous (IV) gadolinium injection has been used to visualize the endolymphatic hydrops (ELH) in Ménière's disease (MD). This study was designed to investigate the ELH characteristics in clinically diagnosed definite MD and to explore the pathology of MD with magnetic resonance imaging (MRI).

METHODS

One hundred fifty-four patients with definite MD were included in this study. All patients underwent the IV method. The grades of ELH were analyzed on each image, regions of interest of the cochlear perilymph and the cerebellum white matter were determined, and the signal intensity ratio of the former to the latter (CC ratio) on both sides in patients with unilateral MD was subsequently evaluated.

RESULTS

Endolymphatic hydrops was observed in 148 patients (96.1%) on the clinically affected side; the remaining 6 patients (3.9%) had no apparent ELH. One hundred fifteen patients (74.7%) had unilateral ELH, and 33 patients (21.4%) had bilateral ELH. Eighteen patients (11.7%) had ELH on the clinically silent side. Patients with moderate and significant grades of ELH in the vestibule and cochlea accounted for 88.3% and 90.3%, respectively. The CC ratio of the affected side (1.39 ± 0.37) was higher than that of the unaffected side (1.18 ± 0.29) ( P < .01) in 115 patients with unilateral MD.

CONCLUSIONS

Moderate and significant grades of ELH are common in MD; however, the proposed diagnostic criteria are not fully consistent with ELH. The elevated contrast effect in the affected side in patients with unilateral MD may better reflect the pathologic condition of MD.

High Resolution Three-Dimensional Delayed Contrast MRI Detects Endolymphatic Hydrops in Patients With Vertigo and Vestibular Schwannoma

OBJECTIVE

Advances in high resolution magnetic resonance imaging (MRI) have enabled the detection of endolymphatic hydrops (EH), a pathological ballooning of the endolymphatic fluid system, known to be associated with Menière's disease. When a patient has a known diagnosis of vestibular schwannoma and develops recurrent episodic vertigo spells, many surgeons recommend surgical intervention, attributing the vestibular symptoms to the vestibular schwannoma. The aim of this study is to evaluate the clinical outcome in patients with vestibular schwannoma and EH, treated medically, for recurrent spells of vertigo.

PATIENTS

Two patients with EH and vestibular schwannoma who presented with recurrent spells of vertigo are included. Both had characteristic low frequency hearing loss ipsilateral to the schwannoma.

INTERVENTION

MRI sequences with 3T scanner (Skyra, Siemens Healthcare, Erlangen, Germany) using high resolution three-dimensional delayed postcontrast protocol included "cisternographic" T2 and delayed intravenous-enhanced three-dimensional fluid-attenuation inversion recovery (DIVE-3D-FLAIR) sequences, performed with 2350 ms (bright perilymph) and 2050 ms (bright endolymph) inversion times and with subtracted images.

MAIN OUTCOME MEASURE

MRI FLAIR evaluation of EH and presence or absence of vestibular symptoms.

RESULTS

Both patients had resolution of the disabling vertigo spells with a diuretic, and Patient 1 had unchanged EH, while Patient 2 had partial resolution of the EH and the FLAIR hyperintensity.

CONCLUSION

When EH coexists with vestibular schwannoma in a patient presenting with recurrent vertigo spells, medical treatments for EH may alleviate the vestibular symptoms. We recommend that patients with small vestibular schwannomas who present with vertigo spells undergo high resolution MRI to evaluate for EH and undergo a trial of medical treatment with diuretics.

Magnetic resonance volumetric measurement of endolymphatic space in patients without vertiginous or cochlear symptoms

CONCLUSION

Magnetic resonance volumetric measurement of inner ear endolymphatic space (ELS) was performed in patients without vertiginous or cochlear symptoms. The existence of the ELS in patients with chronic rhinosinusitis (CRS) was shown. The ELS in the cochlea and vestibule was classified into four categories. These findings could be useful as a standard reference for further research.

OBJECTIVES

To identify normal values of the ELS in the cochlea and vestibule.

METHODS

Twenty-four patients with CRS were enrolled. Inner ear fluid space images and positive perilymph/positive endolymph images were acquired using a 3.0-tesla unit. Three-dimensional (3-D) images were constructed semi-automatically using both anatomical and tissue information by fusing the 3-D images of the inner ear fluid space and the ELS.

RESULTS

Among all patients, the mean ELS/the total fluid space (TFS) ratio in the cochlea was 8.8% and that in the vestibule was 16.2%. The ELS in the cochlea and vestibule was classified into four categories. Age-related differences were found in the TFS, ELS, and ELS/TFS ratio in the inner ear and the ELS and ELS/TFS ratio in the vestibule.

Investigation of the ototoxicity of gadoteridol (ProHance) and gadodiamide (Omniscan) in mice

CONCLUSION

In the mouse, when a tympanic perforation is present, gadoteridol does not seem to cause ototoxicity. Gadodiamide may cause mild ototoxicity other than toxicity to the outer hair cells of the cochlea.

OBJECTIVES

Endolymphatic hydrops have been visualized through intra-tympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. However, reports on the safety of GBCAs are limited. This study aimed to assess ototoxicity of gadoteridol and gadodiamide.

METHOD

In a prospective, randomized, controlled trial, myringotomies in the left ear were performed in 20 male C57 BL/6 mice. After testing the baseline auditory brainstem response (ABR) (range = 8-32 kHz), the test solution (gadoteridol, gadodiamide, saline, or cisplatin) was injected into the left ear. ABR testing was repeated 14 days after test solution application. In morphological experiments, images of post-mortem surface preparations were assessed for cochlear hair cell status.

RESULTS

At 14 days following gadoteridol application, there was no significant change in ABR thresholds at 8, 16, or 32 kHz. Gadodiamide application caused a significant change in the ABR threshold at 8 kHz. Apparent cochlear hair cell loss was not observed in the surface preparation after gadoteridol or gadodiamide application.

Sustained Effect of Hyaluronic Acid in Subcutaneous Administration to the Cochlear Spiral Ganglion

The spatiotemporal distribution of drugs in the inner ear cannot be precisely evaluated because of its small area and complex structure. In the present study, we used hyaluronic acid (HA)-dispersed luciferin to image transgenic mice and to determine the effect of HA on controlled drug delivery to the cochlea. GFAP-luc mice, which express luciferase in cochlear spiral ganglion cells, were subcutaneously administered HA-luciferin (HA-sc) or luciferin dissolved in saline (NS-sc) or intraperitoneally administered luciferin dissolved in saline (NS-ip). The bioluminescence of luciferin was monitored in vivo in real time. The peak time and half-life of fluorescence emission were significantly increased in HA-sc-treated mice compared with those in NS-sc- and NS-ip-treated mice; however, significant differences were not observed in peak photon counts. We detected differences in the pharmacokinetics of luciferin in the inner ear, including its sustained release, in the presence of HA. The results indicate the clinical potential of using HA for controlled drug delivery to the cochlea.

Changes in endolymphatic hydrops in patients with Ménière's disease treated conservatively for more than 1 year

CONCLUSION

This study revealed that endolymphatic hydrops (EH) reduced in some cases with Ménière's disease (MD) treated conservatively. It appears that the EH reduction was associated with improvement of the clinical symptoms.

OBJECTIVES

The relationship between the degree of EH and clinical symptoms is not clear at present. The purpose of the present study was to investigate the time course of the relationship in patients with MD treated conservatively.

PATIENTS

Twelve patients with MD treated conservatively for more than 1 year in a university hospital.

METHODS

Twenty ears of 12 patients with MD treated conservatively were evaluated. The presence or absence of vertigo, tinnitus and ear fullness was confirmed when magnetic resonance imaging (MRI) was performed. Using a 3 T MRI scanner, three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) MRI was performed 2 or 3 times 24 hours after intra-tympanic gadolinium injection or 4 hours after intravenous gadolinium injection.

RESULTS

In the three ears in which the symptoms alleviated, EH was reduced in two ears, but EH was reduced in only one of 17 ears in which the symptoms did not alleviate. The Fisher exact test revealed that EH reduction occurred more frequently in ears with alleviation of the symptoms (p < 0.05).

The Technical and Clinical Features of 3D-FLAIR in Neuroimaging

In clinical MR neuroimaging, 3D fluid-attenuated inversion recovery (3D-FLAIR) with a variable-flip-angle turbo spin echo sequence is becoming popular. There are more than 100 reports regarding 3D-FLAIR in the PubMed database. In this article, the technical and clinical features of 3D-FLAIR for neuroimaging are reviewed and summarized. 3D-FLAIR allows thinner slices with multi-planar reformation capability, a higher flow sensitivity, high sensitivity to subtle T1 changes in fluid, images without cerebrospinal fluid (CSF) inflow artifacts, and a 3D dataset compatible with computer-aided analysis. In addition, 3D-FLAIR can be obtained within a clinically reasonable scan time. It is important for radiologists to be familiar with the features of 3D-FLAIR and to provide useful information for patients.

MR volumetric assessment of endolymphatic hydrops

OBJECTIVES

We aimed to volumetrically quantify endolymph and perilymph spaces of the inner ear in order to establish a methodological basis for further investigations into the pathophysiology and therapeutic monitoring of Menière's disease.

METHODS

Sixteen patients (eight females, aged 38-71 years) with definite unilateral Menière's disease were included in this study. Magnetic resonance (MR) cisternography with a T2-SPACE sequence was combined with a Real reconstruction inversion recovery (Real-IR) sequence for delineation of inner ear fluid spaces. Machine learning and automated local thresholding segmentation algorithms were applied for three-dimensional (3D) reconstruction and volumetric quantification of endolymphatic hydrops. Test-retest reliability was assessed by the intra-class coefficient; correlation of cochlear endolymph volume ratio with hearing function was assessed by the Pearson correlation coefficient.

RESULTS

Endolymph volume ratios could be reliably measured in all patients, with a mean (range) value of 15% (2-25) for the cochlea and 28% (12-40) for the vestibulum. Test-retest reliability was excellent, with an intra-class coefficient of 0.99. Cochlear endolymphatic hydrops was significantly correlated with hearing loss (r = 0.747, p = 0.001).

CONCLUSIONS

MR imaging after local contrast application and image processing, including machine learning and automated local thresholding, enable the volumetric quantification of endolymphatic hydrops. This allows for a quantitative assessment of the effect of therapeutic interventions on endolymphatic hydrops.

KEY POINTS

• Endolymphatic hydrops is the pathological hallmark of Menière's disease. • Endolymphatic hydrops can be visualized by locally enhanced ultra-high-resolution MR imaging. • Computer-aided image processing enables quantification of endolymphatic hydrops. • Endolymphatic hydrops correlates with hearing loss in patients with Menière's disease. • Therapeutic trials in Menière's disease can be monitored with this quantitative approach.

Visualization of white matter tracts using a non-diffusion weighted magnetic resonance imaging method: does intravenous gadolinium injection four hours prior to the examination affect the visualization of white matter tracts?

Objectives

Visualization of white matter (WM)-tracts such as the corticospinal tract (CST), medial lemniscus (ML), and superior cerebellar peduncle (SCP) using delayed enhanced (DE)-heavily T2-weighted three-dimensional fluid-attenuated inversion-recovery (hT2w-3D-FLAIR) imaging has recently been reported. In that report, all patients were clinically suspected of having Ménière’s disease, because DE-hT2w-3D-FLAIR imaging of the inner ear has been reported to separately visualize perilymph and endolymph fluid and can identify the presence of endolymphatic hydrops. Therefore, the previous report could not rule out the possible effect of delayed enhancement. From this perspective, the purpose of this study was to elucidate if the use of gadolinium affects the visualization of WM-tracts on hT2w-3D-FLAIR.

Materials and Methods

The records of nine patients with suspected Ménière’s disease who underwent plain (P) and DE-hT2w-3D-FLAIR by 3-Tesla were retrospectively analyzed. The regions of interest were set on the CST, ML, and SCP, and on contiguous brain parenchyma: The thalamus (Th), pontine parenchyma (PP), and cerebellar parenchyma (CP), respectively. The signal intensity ratio between each WM-tract and the relevant contiguous brain parenchyma was calculated for both P- and DE-hT2w-3D-FLAIR images, and statistically compared using paired t-tests.

Results

The CST/Th signal intensity ratio was 3.75±0.67 on P-hT2w-3D-FLAIR and 3.62±0.50 on DE-hT2w-3D-FLAIR (p = 0.24). The ML/PP signal intensity ratio was 2.19±0.59 on P-hT2w-3D-FLAIR and 2.08±0.53 on DE-hT2w-3D-FLAIR (p = 0.25). The SCP/CP signal intensity ratio was 4.08±0.91 on P-hT2w-3D-FLAIR and 4.04±0.96 on DE-hT2w-3D-FLAIR (p = 0.43). There were no significant differences in the signal intensity ratios between P- and DE-hT2w-3D-FLAIR images.

Conclusions

The use of gadolinium is not necessary for visualization of WM-tracts using hT2w-3D-FLAIR, and P-hT2w-3D-FLAIR without gadolinium may have future clinical applications as an imaging procedure.

Diluted gadoteridol (ProHance®) causes mild ototoxicity in cochlear outer hair cells

CONCLUSION

Administration of diluted solutions of gadoteridol might cause considerably less toxic effects on cochlear outer hair cells (OHCs).

OBJECTIVES

Visualization of endolymphatic hydrops is done by intratympanic injection of gadolinium-based contrast agents (GBCAs) and three-dimensional fluid-attenuated inversion recovery (3-D FLAIR) magnetic resonance imaging. Here, we investigated the physiological and morphological responses of guinea pig cochlear cells to gadoteridol.

METHODS

Distortion product otoacoustic emission (DPOAE) levels were measured before and 1, 2, and 4 weeks after intratympanic injection of 1/8 or 1/16 dilution of gadoteridol in guinea pigs. Morphological changes in isolated cochlear OHCs were observed after application of gadoteridol and GdCl3.

RESULTS

At the highest frequency (F2 = 12 000 Hz), DPOAE level was significantly (p < 0.05) lower in the 1/8 diluted gadoteridol group than in the control group. Cell shape changes were observed in 24% (6/25) and 3% (1/33) of OHCs after application of 1/8 and 1/16 diluted gadoteridol, respectively. The occurrence of morphological damage was significantly lower after application of saline compared with 1/8 diluted gadoteridol. Morphological damage was significantly lower after application of 1/16 diluted gadoteridol compared with 1/8 diluted gadoteridol (p < 0.05). Morphological damage was observed at a high rate (8/10 cells, 80%) after application of GdCl3.

Magnetic resonance imaging of the inner ear after both intratympanic and intravenous gadolinium injections

CONCLUSION

Using magnetic resonance imaging (MRI), endolymphatic hydrops could be visualized on both sides after intratympanic (IT) injection of gadolinium contrast agents (Gd) in one symptomatic ear and subsequent intravenous (IV) Gd injection. The MRI revealed a difference of intracochlear Gd distribution between the IT injection side and the contralateral IV side.

OBJECTIVES

Although the IT method allows greater enhancement of the perilymph, many patients feel reluctance in receiving the IT injection in asymptomatic ears. We attempted to evaluate endolymphatic space size on both sides without the IT injection in asymptomatic ears.

METHODS

In 10 patients with Meniere's disease, MRI was performed 24 h after the IT Gd injection in one symptomatic ear and 4 h after the IV Gd injection. The signal intensity of Gd in the basal and apical turns of the cochlea was evaluated.

RESULTS

The signal intensity in the scala tympani of the basal turn of the cochlea was 1.70 ± 0.60 on the IT + IV side and 0.42 ± 0.10 on the contralateral (IV) side. Gd was distributed uniformly in the scala tympani in the cochlea on the IV side, whereas it was strongly localized in the basal turn on the IT + IV side.