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

Abstract

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 Role of Wideband Tympanometry in the Diagnosis of Meniere's Disease

“…Studies have proved that MD is associated with endolymphatic hydrops (EH), which cause an enlarged endolymphatic space in the inner ear (IE) (1,5). The presence of EH can be verified non-invasively by intravenous injection of delayed gadolinium-enhanced magnetic resonance imaging of the IE (6). The measurement of intralabyrinthine pressure allows a better understanding of MD (7).…”

IE-Vnet: Deep Learning-Based Segmentation of the Inner Ear's Total Fluid Space

“…At first glance, clinical radiology approaches offer fast and easily applicable visual semi-quantitative (SQ) ELH classifications ( 4 – 9 ). Nevertheless, given the plurality of visual SQ ELH classification approaches that may vary in wording, resolution (3- or 4-point ordinal scale), or evaluation level (anatomical fixpoint), and can be sensitive to human bias, published results cannot be considered inherently reproducible, comparable or standardized ( 10 ). Already an improvement in comparability, manual measurement of the ELS area in 2D within one MR-layer ( 11 , 12 ), or better yet, the entire ELS volume 3D over multiple MR-layers ( 13 , 14 ) remain dependent on human decisions.…”

A non-invasive, automated diagnosis of Menière’s disease using radiomics and machine learning on conventional magnetic resonance imaging: A multicentric, case-controlled feasibility study

“…This technique enables the in-vivo confirmation of EH. Various methods have been proposed to qualitatively and quantitatively assess the endolymphatic space [10]. Most recent developments even allow the fully automatic 3D segmentation and Marc van Hoof, Raymond van de Berg have equally contributed to do this work volumetric quantification of the endolymphatic space [12,13], a significant step towards automatization and standardization of EH assessment on imaging.…”

“…Nevertheless, EH is not a pathognomic feature to MD. It is observed in various neuro-otologic pathologies as well as in asymptomatic ears [10][11][12]14]. The exact relationship between EH and MD and its pathological and clinical relevance are not completely understood.…”

“…Therefore, new imaging techniques are under investigation as a MD diagnostic [ 8 , 9 ]. Nowadays, the most commonly applied technique in clinical practice is delayed gadolinium-enhanced MRI [ 10 , 11 ]. This technique enables the in-vivo confirmation of EH.…”