Cochlear Lymph Fluid Signal Increase in Patients with Otosclerosis after Intravenous Administration of Gadodiamide

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.

Increased signal intensity with delayed post contrast 3D-FLAIR MRI sequence using constant flip angle and long repetition time for inner ear evaluation

PURPOSE

The purpose of this study was to compare the degree of perilymphatic enhancement between 4 hour post-contrast constant flip angle three-dimensional fluid attenuated inversion recovery (3D-FLAIR) images obtained with short repetition time (TR) and those obtained with long TR.

MATERIALS AND METHODS

This single-center, prospective study included patients who underwent MRI of the inner ear with heavily T2-weighted sequence, 3D-FLAIR sequence with a "short" TR of 10,000 ms (s3D-FLAIR) and with a "long" TR of 16,000 ms (l3D-FLAIR). Signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) obtained with s3D-FLAIR and l3D-FLAIR were quantitatively assessed using region of interest (ROI) method and compared. The morphology of the endolymphatic space on both sequences was also evaluated.

RESULTS

From March 2020 to July 2020, 20 consecutive patients were enrolled (9 women and 11 men; mean age, 52.1 ± 14.5 [SD] years; age range: 29-75 years). On l3D-FLAIR images, mean SIR (21.1 ± 8.8 [SD]; range: 7.6-46.1) was significantly greater than that on s3D-FLAIR images (15.7 ± 6.7 [SD]; range: 5.9-33.4) (P < 0.01). On l3D-FLAIR images, mean CNR (17 ± 8.5 [SD]; range: 2-40) was significantly greater than that on s3D-FLAIR images (12 ± 6.3 [SD]; range: 3.2-29.8) (P < 0.01). Kappa value for inter-rater agreement for endolymphatic hydrops, vestibular atelectasis and perilymphatic fistula were 0.93 (95% CI: 0.74-1), 1 (95% CI: 0.85-1) and 1 (95% CI: 0.85-1) respectively.

CONCLUSION

This study demonstrates that the sensitivity of 3D-FLAIR sequences to low concentration gadolinium in the perilymphatic space is improved by elongation of the TR, with SIR and CNR increased by +34.4% and +41.3% respectively.

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.

MRI With Gadolinium as a Measure of Blood-Labyrinth Barrier Integrity in Patients With Inner Ear Symptoms: A Scoping Review

Objective: Capillaries within the inner ear form a semi-permeable barrier called the blood-labyrinth barrier that is less permeable than capillary barriers elsewhere within the human body. Dysfunction of the blood-labyrinth barrier has been proposed as a mechanism for several audio-vestibular disorders. There has been interest in using magnetic resonance imaging (MRI) with intravenous gadolinium-based contrast agents (GBCA) as a marker for the integrity of the blood labyrinth barrier in research and clinical settings. This scoping review evaluates the evidence for using intravenous gadolinium-enhanced MRI to assess the permeability of the blood-labyrinth barrier in healthy and diseased ears.

Methods: A systematic search was conducted of three databases: PubMed, EMBASE, CINAHL PLUS. Studies were included that used GBCA to study the inner ear and permeability of the blood-labyrinth barrier. Data was collected on MRI protocols used and inner ear enhancement patterns of healthy and diseased ears in both human and animal studies.

Results: The search yielded 14 studies in animals and 53 studies in humans. In healthy animal and human inner ears, contrast-enhanced MRI demonstrated gradual increase in inner ear signal intensity over time that was limited to the perilymph. Signal intensity peaked at 100 min in rodents and 4 h in humans. Compared to controls, patients with idiopathic sudden sensorineural hearing loss and otosclerosis had increased signal intensity both before and shortly after GBCA injection. In patients with Ménière's disease and vestibular schwannoma, studies reported increased signal at 4 h, compared to controls. Quality assessment of included studies determined that all the studies lacked sample size justification and many lacked adequate control groups or blinded assessors of MRI.

Conclusions: The included studies provided convincing evidence that gadolinium crosses the blood-labyrinth barrier in healthy ears and more rapidly in some diseased ears. The timing of increased signal differs by disease. There was a lack of evidence that these findings indicate general permeability of the blood-labyrinth barrier. Future studies with consistent and rigorous methods are needed to investigate the relationship between gadolinium uptake and assessments of inner ear function and to better determine whether signal enhancement indicates permeability for molecules other than gadolinium.

Clinical Practice Guideline: Ménière's Disease

OBJECTIVE

Ménière's disease (MD) is a clinical condition defined by spontaneous vertigo attacks (each lasting 20 minutes to 12 hours) with documented low- to midfrequency sensorineural hearing loss in the affected ear before, during, or after one of the episodes of vertigo. It also presents with fluctuating aural symptoms (hearing loss, tinnitus, or ear fullness) in the affected ear. The underlying etiology of MD is not completely clear, yet it has been associated with inner ear fluid (endolymph) volume increases, culminating in episodic ear symptoms (vertigo, fluctuating hearing loss, tinnitus, and aural fullness). Physical examination findings are often unremarkable, and audiometric testing may or may not show low- to midfrequency sensorineural hearing loss. Conventional imaging, if performed, is also typically normal. The goals of MD treatment are to prevent or reduce vertigo severity and frequency; relieve or prevent hearing loss, tinnitus, and aural fullness; and improve quality of life. Treatment approaches to MD are many and typically include modifications of lifestyle factors (eg, diet) and medical, surgical, or a combination of therapies.

PURPOSE

The primary purpose of this clinical practice guideline is to improve the quality of the diagnostic workup and treatment outcomes of MD. To achieve this purpose, the goals of this guideline are to use the best available published scientific and/or clinical evidence to enhance diagnostic accuracy and appropriate therapeutic interventions (medical and surgical) while reducing unindicated diagnostic testing and/or imaging.

MRI evaluation of the endolymphatic space in otosclerosis and correlation with clinical findings

PURPOSE

The purpose of this study was to investigate the clinical features of ears with otosclerosis and their correlation with endolymphatic hydrops and blood-labyrinth barrier (BLB) impairment on 3T magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This was a single-center retrospective imaging study. Thirty-nine ears from 29 patients (17 men, 12 women; mean age 52±12 [SD] years; range 27-74 years) with non-operated otosclerosis were included. All patients underwent three-dimensional fluid attenuated inversion recovery (FLAIR) MRI sequences performed 4hours after the intravenous administration of a single dose of gadolinium-based contrast material. MRI examinations were analyzed by two radiologists for the presence of saccular hydrops (SH) and BLB impairment. Results of MRI examinations were compared with clinical findings, hearing levels and extent of otosclerotic lesions based on high-resolution computed tomography findings. BLB impairment was evaluated using the signal intensity ratio, ratio of intensities between the basal turn of the cochlea and the medulla.

RESULTS

SH was observed in 1/39 (3%) otosclerotic ears and BLB impairment in 8/39 (21%) while 8/29 patients with otosclerosis (28%) had vertigo. No significant associations were found between SH or BLB impairment on MRI, and the presence of vertigo or the degree of sensorineural hearing loss.

CONCLUSION

Clinical manifestations of otosclerosis (sensorineural hearing loss and rotatory vertigo) were not significantly associated with MRI findings such as BLB impairment and endolymphatic hydrops. SH was only observed in one patient with obstruction of the vestibular aqueduct by an otosclerotic focus.

Comparison of Enhancement of the Vestibular Perilymph between Variable and Constant Flip Angle-Delayed 3D-FLAIR Sequences in Menière Disease

BACKGROUND AND PURPOSE

Endolymphatic hydrops in patients with Menière disease relies on delayed postcontrast 3D-FLAIR sequences. The purpose of this study was to compare the degree of perilymphatic enhancement and the detection rate of endolymphatic hydrops using constant and variable flip angles sequences.

MATERIALS AND METHODS

This was a retrospective study performed in 16 patients with Menière disease who underwent 3T MR imaging 4 hours after gadolinium injection using two 3D-FLAIR sequences with a constant flip angle at 140° for the first and a heavily-T2 variable flip angle for the second. The signal intensity ratio was measured using the ROI method. We graded endolymphatic hydrops and evaluated the cochlear blood-labyrinth barrier impairment.

RESULTS

Both for symptomatic and asymptomatic ears, the median signal intensity ratio was significantly higher with the constant flip angle than with the heavily-T2 variable flip angle (7.16 versus 1.54 and 7.00 versus 1.45, P < .001). Cochlear blood-labyrinth barrier impairment was observed in 4/18 symptomatic ears with the heavily-T2 variable flip angle versus 8/19 with constant flip angle sequences. With heavily-T2 variable flip angle sequences, endolymphatic hydrops was observed in 7-10/19 symptomatic ears versus 12/19 ears with constant flip angle sequences. We found a significant association between the clinical symptomatology and the presence of endolymphatic hydrops with constant flip angle but not with heavily-T2 variable flip angle sequences. Interreader agreement was always perfect with constant flip angle sequences while it was fair-to-moderate with heavily-T2 variable flip angle sequences.

CONCLUSIONS

3D-FLAIR constant flip angle sequences provide a higher signal intensity ratio and are superior to heavily-T2 variable flip angle sequences in reliably evaluating the cochlear blood-labyrinth barrier impairment and the endolymphatic space.

Electrophysiological and inner ear MRI findings in patients with bilateral vestibulopathy

PURPOSE

Bilateral vestibulopathy (BV) is an uncommon disorder and the etiology remained idiopathic in most cases. Delayed 3D-FLAIR sequences have provided new insights into various inner ear diseases, allowing the evaluation of the endolymphatic space and the permeability of the blood-labyrinthine barrier (BLB). The aim of this study was to assess both the morphology of the endolymphatic space and the permeability of the BLB in patients with BV as evaluated by delayed 3D-FLAIR sequences.

METHODS

In this retrospective study, we performed 3D-FLAIR sequences 4 h after administering contrast media to 42 patients with BV. Two radiologists independently evaluated the morphology of the endolymphatic space (either vestibular atelectasis or endolymphatic hydrops) and the permeability of the BLB.

RESULTS

Morphologic anomalies of the endolymphatic space and vestibular blood-labyrinthine barrier impairment were observed in 59.6% of patients with BV. Bilateral vestibular atelectasis (VA) was found in 21 patients (50%), involving only the utricle and all three ampullas while the saccule was always observed with no sign of collapse: idiopathic BV (n = 19), aminoglycoside administration (n = 1) and few days following abdominal surgery (n = 1). One patient had bilateral vestibular malformation. BLB impairment was observed in five patients (11.9%): paraneoplastic (n = 1), lymphoma (n = 1), autoimmune (n = 1), and vestibular "neuritis" (n = 2). Seventeen patients (40.4%) had normal MRI with no endolymphatic space anomaly or BLB impairment.

CONCLUSION

Patients with BV presented with morphologic anomalies of the endolymphatic space or BLB impairment in 59.6% of patients.

The value of four stage vestibular hydrops grading and asymmetric perilymphatic enhancement in the diagnosis of Menière's disease on MRI

Purpose

There is still a clinical-radiologic discrepancy in patients with Menière’s disease (MD). Therefore, the purpose of this study was to investigate the reliability of current MRI endolymphatic hydrops (EH) criteria according to Baráth in a larger study population and the clinical utility of new imaging signs such as a supplementary fourth low-grade vestibular EH and the degree of perilymphatic enhancement (PE) in patients with Menière’s disease (MD).

Methods

This retrospective study included 148 patients with probable or definite MD according to the 2015 American Academy of Otolaryngology, Head and Neck Surgery criteria who underwent a 4-h delayed intravenous Gd-enhanced 3D-FLAIR MRI between January 2015 and December 2016. Vestibular EH, vestibular PE, cochlear EH, and cochlear PE were reviewed twice by three experienced readers. Cohen’s Kappa and multivariate logistic regression were used for analysis.

Results

The intra- and inter-reader reliability for the grading of vestibular-cochlear EH and PE was excellent (0.7 < kappa < 0.9). The two most distinctive characteristics to identify MD are cochlear PE and vestibular EH which combined gave a sensitivity and specificity of 79.5 and 93.6%. By addition of a lower grade vestibular EH, the sensitivity improved to 84.6% without losing specificity (92.3%). Cochlear EH nor vestibular PE showed added-value.

Conclusions

MRI using vestibular-cochlear EH and PE grading system is a reliable technique. A four-stage vestibular EH grading system in combination with cochlear PE assessment gives the best diagnostic accuracy to detect MD.

3D fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging at different stages of otosclerosis

PURPOSE

The aim of this work is to study otosclerotic patients by 3D-FLAIR (fluid attenuated inversion recovery) sequence magnetic resonance imaging (MRI) with and without Gadolinium administration (-/+ Gd), to understand whether there is a direct relationship between radiological findings at 3D FLAIR MRI sequences and some clinical features of otosclerosis, such as the presence and entity of sensorineural involvement, duration of disease, patient gender, and other factors.

METHODS

38 patients affected by different stages of unilateral or bilateral otosclerosis underwent 3D FLAIR MRI+/- Gd. 11 subjects with normal hearing, previously submitted to 3T MRI for other minor diseases, unrelated with otosclerosis, had been retrospectively enrolled as control group.

RESULTS

We found significant correlations between 3D FLAIR MRI findings and some clinical features of otosclerosis, such as severity of cochlear damage (in terms of entity of sensorineural loss) and duration of disease. These findings indicate that at 3D-FLAIR MRI different patterns may depend on the level of blood labyrinth barrier damage in the cochlea, and be related to different stages of cochlear involvement in otosclerotic patients.

CONCLUSIONS

We believe that our findings may contribute in understanding the pathogenesis of cochlear damage in otosclerosis and may have further prognostic value. Our results led us to consider the possible use of 3D-FLAIR sequences in monitoring the effectiveness of any medical therapy of otosclerosis and in selecting the patients eligible for treatment.

Differences in Signal Intensity and Enhancement on MR Images of the Perivascular Spaces in the Basal Ganglia versus Those in White Matter

Purpose:

To elucidate differences between the perivascular space (PVS) in the basal ganglia (BG) versus that found in white matter (WM) using heavily T₂-weighted FLAIR (hT₂-FL) in terms of 1) signal intensity on non-contrast enhanced images, and 2) the degree of contrast enhancement by intravenous single dose administration of gadolinium based contrast agent (IV-SD-GBCA).

Materials and Methods:

Eight healthy men and 13 patients with suspected endolymphatic hydrops were included. No subjects had renal insufficiency. All subjects received IV-SD-GBCA. MR cisternography (MRC) and hT₂-FL images were obtained prior to and 4 h after IV-SD-GBCA. The signal intensity of the PVS in the BG, subinsular WM, and the cerebrospinal fluid (CSF) in Ambient cistern (CSF_AC) and CSF in Sylvian fissure (CSF_Syl) was measured as well as that of the thalamus. The signal intensity ratio (SIR) was calculated by dividing the intensity by that of the thalamus. We used 5% as a threshold to determine the significance of the statistical test.

Results:

In the pre-contrast scan, the SIR of the PVS in WM (Mean ± standard deviation, 1.83 ± 0.46) was significantly higher than that of the PVS in the BG (1.05 ± 0.154), CSF_Syl (1.03 ± 0.15) and the CSF_AC (0.97 ± 0.29). There was no significant difference between the SIR of the PVS in the BG compared to the CSF_AC and CSF_Syl. For the evaluation of the contrast enhancement effect, significant enhancement was observed in the PVS in the BG, the CSF_AC and the CSF_Syl compared to the pre-contrast scan. No significant contrast enhancement was observed in the PVS in WM.

Conclusion:

The signal intensity difference between the PVS in the BG versus WM on pre-contrast images suggests that the fluid composition might be different between these PVSs. The difference in the contrast enhancement between the PVSs in the BG versus WM suggests a difference in drainage function.

Endolymphatic hydrops imaging: Differential diagnosis in patients with Meniere disease symptoms

PURPOSE

The goal of this retrospective study was to investigate the differential diagnosis of endolymphatic hydrops in patients with Meniere's disease (MD) symptoms by using magnetic resonance imaging (MRI) with intravenous injection of gadolinium chelate and delayed acquisition.

MATERIAL AND METHOD

Two hundred patients (133 women, 67 men; mean age=67.2±11 ([SD] years) with unilateral MD underwent MRI at 3-T, between 4.5 and 5.5hours after intravenous administration of gadoterate meglumine at a dose of 0.1mmol/kg. MR images were analyzed for the presence of saccular hydrops, perilymphatic fistulae, inner ear malformations, semicircular canal (SCC) abnormal enhancement and brain lesions. We also tested the potential relationship between past history of gentamicin intratympanic administration and perilymphatic fistula presence and SCC aspect.

RESULTS

Saccular hydrops were found in 96/200 patients with MD (48%). Three patients (1.5%) had perilymphatic fistulas associated with saccular hydrops, as confirmed by surgery. There was a correlation between the presence of perilymphatic fistula and past history of intratympanic gentamicin administration (P=0.02). We detected inner ear malformations in 5 patients (2.5%), SCC local enhancement in 15 patients (7.5%) always on the same side than the clinical symptoms of MD. There was a correlation between the presence of SCC abnormal enhancement and past intratympanic gentamicin administration (P=0.001). Five patients (2.5%) had brain lesions along central cochleovestibular pathways.

CONCLUSION

MRI may reveal brain lesions, SCC abnormalities and perilymphatic fistulae in patients with clinical MD.