Boubaker Fatma, Lane John I, Puel Ulysse, Drouot Guillaume, Witte Robert J, Ambarki Khalid, Teixeira Pedro Augusto Gondim, Blum Alain, Parietti-Winkler Cécile, Vallee Jean-Noel, Gillet Romain, Eliezer Michael
From the Guilloz Imaging Department, Central Hospital, University Hospital of Nancy, 54000 Nancy, France (F.B, U.P,PA.G-T, A.B,R.G); From Department of Radiology, Mayo Clinic, Rochester, MN 55901, USA (JI.L, RJ.W). From Université de Lorraine, CIC, Innovation Technologique, University Hospital Center of Nancy, 54000 Nancy, France (U.P, G.D,PA.G-T, A.B, R.G). From Université de Lorraine, INSERM, IADI, 54000, Nancy, France (U.P, G.D,PA.G-T, A.B, R.G). From Siemens Healthcare SAS, Courbevoie, France (K.A). From ENT Surgery Department, Central Hospital, University Hospital Center of Nancy, 54000 Nancy, France (C.P-W). From Diagnostic and Functional Neuroradiology and Brain stimulation Department, 15-20 National Vision Hospital, Paris University Hospital Center, 75571, Paris, France (JN.V, M.E). From Department of Radiology, Hôpital Américain de Paris, 63 boulevard Victor Hugo 92200 Neuilly-sur-Seine, France (M.E).
AJNR Am J Neuroradiol. 2025 Aug 28. doi: 10.3174/ajnr.A8989.
The labyrinth is a complex anatomical structure in the temporal bone. However, high-resolution imaging of its membranous portion is challenging due to its small size and the limitations of current MRI techniques. Deep Learning Reconstruction (DLR) represents a promising approach to advancing MRI image quality, enabling higher spatial resolution and reduced noise. This study aims to evaluate DLR-High-Resolution 3D-T2 MRI sequences for visualizing the labyrinthine structures, comparing them to conventional 3D-T2 sequences. The goal is to improve spatial resolution without prolonging acquisition times, allowing a more detailed view of the labyrinthine microanatomy.
High-resolution heavy T2-weighted TSE SPACE images were acquired in patients using 3D-T2 and DLR-3D-T2. Two radiologists rated structure visibility on a four-point qualitative scale for the spiral lamina, scala tympani, scala vestibuli, scala media, utricle, saccule, utricular and saccular maculae, membranous semicircular ducts, and ampullary nerves. Ex vivo 9.4T MRI served as an anatomical reference.
DLR-3D-T2 significantly improved the visibility of several inner ear structures. The utricle and utricular macula were systematically visualized, achieving grades ≥3 in 95% of cases (p < 0.001), while the saccule remained challenging to assess, with grades ≥3 in only 10% of cases. The cochlear spiral lamina and scala tympani were better delineated in the first two turns but remained poorly visible in the apical turn. Semicircular ducts were only partially visualized, with grades ≥3 in 12.5-20% of cases, likely due to resolution limitations relative to their diameter. Ampullary nerves were moderately improved, with grades ≥3 in 52.5-55% of cases, depending on the nerve.
While DLR does not yet provide a complete anatomical assessment, it represents a significant step forward in the non-invasive evaluation of inner ear structures. Pending further technical refinements, this approach may help reduce reliance on delayed gadolinium-enhanced techniques for imaging membranous structures.
3D-T2 = Three-dimensional T2-weighted turbo spin-echo; DLR-3D-T2 = improved T2 weighted turbo spinecho sequence incorporating Deep Learning Reconstruction; DLR = Deep Learning Reconstruction.
