Technique And Application Of Gadolinium-enhanced Inner Ear MRI After Intratympanic And Intravenous Injection For Endolymphatic Hydrops In Meniere’s Disease

The continuous development of gadolinium-enhanced inner ear MRI(ie MRI)has gradually make it an important method for clinical detection of endolymphatic hydrops(EH)in Meniere’s disease.At the technical level,this study evaluated the actual detection rate of hydrops in the ears with Meniere’s disease after intravenous injection using the new EH dictation sequence and compared it with the conventional sequences after intra-tympanic injection,so as to provide a reference for the selection of examination methods;we used the sensitive sequence to improve the limitation of low success rate of inner ear imaging by conventional sequence.At the application level,we studied the asymmetry of electrocochleography in patients with unilateral Meniere’s disease and its correlation with gadolinium-enhanced inner ear MR;We investigated the mechanism of vertigo attack in hydropic ear disease using ie MRI,in order to contribute to the clinical application of this technology and the diagnosis and treatment of Meniere’s disease.Part 1 Comparison of Gadolinium-enhanced MRI of Ears with Definite Meniere’s Disease in Endolymphatic Hydrops Detection Between Intratympanic and Intravenous InjectionObjective We aimed to compare the success rate and EH detection rate of gadolinium-enhanced MRI in ears with definite Meniere’s disease between intratympanic and intravenous injection.Methods A total of 122 ears with definite Meniere’s disease were included and divided into intratympanic group(n=38 ears)and intravenous group(n=84 ears)according to the administration method of contrast agent.Ears in the intratympanic administration group(IT group)underwent 3D-real IR and 3DFLAIR sequence scans of inner ear 24 hours after intratympanic injection of 8-fold diluted Gd-DTPA.Ears in the intravenous group(IV group)was performed i3D-real IR sequence scans 4.5 hours after intravenous Gd-DTPA administration.The success rate of visualization of the inner ear and the detection rate of EH were evaluated by 2 experienced radiologists.Chi-square test was used to compare the success rate and the detection rate of EH between the two groups.Identify the cause for failure of inner ear visualization using high-resolution temporal bone CT.Results In IV group,the success rate of i3D-real IR sequence in ears with Meniere’s disease was 100%,which was statistically higher than that of 3D-real IR(76.32%)and 3D-FLAIR sequence(84.21%)in IT group.In IT group,the actual EH detection rates by 3D-real IR and 3D-FLAIR sequences were 76.32%and 78.95%,respectively,with no statistical difference(P>0.05).In IV group,the actual EH detection rate by i3D-real IR sequence was 98.81%,which was higher than that of 3D-real IR and 3D-FLAIR sequences in IT group(both P<0.05).In IT group,15.79%(6/38)of the examined ears could not accurately assess the presence of EH due to too weak perilymph enhancement.However,in the ears with successful inner-ear visualization,the EH detection rates in IT and IV groups had no statistical difference(P>0.05).Temporal bone HRCT of the 2 patients with failed inner-ear visualization in IT group found that there were anatomical barriers to the niche of the round window,which probably blocked the uptake of gadolinium by the inner ear.Conclusion The success rate and detection rate of EH of i3D-real IR sequence after intravenous injection of 1.5 dosages gadolinium are high and i3D-real IR is suitable for clinical application.In clinical setting,the success rate of intratympanic injection of gadolinium-enhanced inner ear MRI is significantly lower than that of intravenous administration,which affects the detection rate of EH in patients Ménière’s disease.The method can be recommended according to the purpose of MRI and whether there are contraindications and the actual EH detection rate.HRCT of the temporal bone can be used to investigate structural abnormalities that hampers the uptake of gadolinium.Part 2 Clinical application of MIIRMR as a salvage method in gadolinium-enhanced magnetic resonance imaging after intra-tympanic injection Objective We investigated the inner ear visualization success rate and EH detection rates of 3D-FLAIR and 3D-real IR,and whether salvage medium inversion-time inversion-recovery imaging with magnitude reconstruction(MIIRMR)could improve EH detection.Methods Fifty-one patients(102 ears)with episodic or chronic vestibular syndrome were injected intratympanically with 8-fold diluted gadolinium,and 3D-FLAIR and 3D-real IR images obtained 24-h post-injection.If 3DFLAIR inner ear visualization 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 3D-FLAIR and 3D-real IR were 88.90% and72.55%,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.3D-FLAIR+3D-real IR+MIIRMR had92.11% sensitivity,79.68% specificity,72.92% positive-predictive value,and 94.44% negative-predictive value for MD diagnosis.Conclusion MIIRMR can improve success and EH detection rates when 3DFLAIR fails,and help to overcome the limitation of the low success rate of gadolinium-enhanced inner ear MRI after intratympanic injection.Combined MIIRMR+3D-FLAIR+3D-real IR is more valuable for diagnosing MD than conventional sequences.Part 3 Study of asymmetry of electrocochleography in patients with unilateral definite Ménière’s disease and its association with gadolinium-enhanced inner ear MRIObjective Electrocochleography(ECoch G),calorie test and vestibular evoked myogenic potential are important reference indicators for the diagnosis and functional evaluation of Meniere’s disease.This study focused on the asymmetry of ECoch G in patients with unilateral definite Ménière’s disease and its diagnostic value.Methods Thirty-five healthy controls and 93 patients with unilateral definite Meniere’s disease were included in this study.The electrocochleograms of both ears of the two groups were recorded using clicks ECoch G,and the-SP/AP amplitude ratio,ration of-SP/AP amplitude ratio(hereinafter referred to as ECoch G ratio),and asymmetry ratio of-SP/AP amplitude ratio(hereinafter referred to as ECoch G asymmetry ratio),were calculated and evaluated.Patients with Meniere’s disease underwent intravenous injection of gadolinium-enhanced inner ear MRI.ROC curves were used to determine the best diagnostic cut-off values for the three parameters individually and the diagnostic performance when used in combination,and the association between gadolinium-enhanced inner ear MR and Ecoch G was assessed using chi-square and Spearman tests.Results The ECoch G-SP/AP amplitude ratio,ECoch G ratio,and ECoch G asymmetry ratio in diseased ears of patients with unilateral definite Meniere’s disease were higher than those of ears of healthy control,and the difference was statistically significant(P<0.05).According to the ROC curve,the best diagnostic cut-off value of the amplitude ratio of electrocochleogram-SP/AP in this hearing center is 0.35,and the best diagnostic cut-off value of ECoch G ratio is 1.32.The optimal diagnostic cutoff for the ECoch G asymmetry ratio is 0.17.Sensitivity of ECoch G-SP/AP amplitude ratio,ECoch G ratio,ECoch G asymmetry ratio and combined of these three were 54.84%,72.04%,63.44% and 82.80%,respectively.Specificity of these four metrics were 94.29%,85.71%,94.29% and 91.43%,respectively.Positive-predictive value of these four metrics were 96.23%,93.06%,96.72% and 96.25%,respectively.Negative-predictive value of these four metrics were 44.00%,53.57%,49.25%,and 66.67%,respectively.AUC of these four metrics were 0.729,0.740,0.740 and 0.928,respectively.Combined of ECoch G metrics increased the diagnostic values,and the positive rate of ECoch G metrics in combination with gadolinium-enhanced MRI reached 100%.In the ears of patients with unilateral definite Meniere’s disease,Ecoch G-SP/AP amplitude ratio was not associated with the grade of cochlear EH,but weakly correlated with the grade of vestibular EH(rs=0.260,P=0.012).Both of ECoch G ratio and asymmetry ratio did not correlate with the grade of cochlear or vestibular EH.Conclusion ECoch G asymmetry is present in patients with unilateral definite Ménière’s disease.ECoch G ratio and ECoch G asymmetry ratio can be used as indicators to improve the diagnostic performance of ECoch G for definite Ménière’s disease.When ECoch G is negative,gadolinium-enhanced MRI of the inner ear with a higher positive rate can still be used to further search for evidence of EH.Part 4 Intravenous gadolinium-enhanced inner ear MRI of two patients with hydropic ear disease during a vertigo attackObjective This chapter reports the MRI changes of ears in a patient with Ménière’s disease(MD)before and during a vertigo attack and a patient with delayed endolymphatic hydrops(DEH)during a vertigo attack and after that episode,providing imaging-based evidence for the study of the mechanism of vertigo attack in hydropic ear disease(HED).Methods A patient with MD completed intravenous gadolinium-enhanced inner ear MRI during an intermittent period.The next day,the patient completed the re-examination of inner ear MRI during a vertigo attack.A patient with DEH completed gadolinium-enhanced inner ear MRI during a vertigo attack and the intermission period after the vertigo attack the next day.Results There was no evidence of obvious rupture of the membrane labyrinth and mixing of perilymph and endolymph in the two cases of HED during the vertigo attack.Inner ear MRI revealed a decrease in EH volume in patients with Meniere’s disease during a vertigo attack compared with period before the attack.In patients with DEH,the volume of vestibular EH was still reduced after the vertigo attack was relieved.These findings suggested that EH volume in patients with DEH may be changing before and after a vertigo attack.In patients with DEH no significant improvement in cochlear EH was observed after the attack.Conclusion The dynamic changes of endolymph in the inner ear revealed by inner ear during and after a vertigo attack in patients with HED provide new clues for exploring the mechanism of vertigo attacks in HED,which is worthy of further study.