High Signal Intensity of the Cochlear Modiolus on Unenhanced T1-Weighted Images in Classical Infratentorial Superficial Siderosis

• Published in: YONAGO ACTA MEDICA Vol. 65; no. 4; pp. 270 - 277
• Main Authors: Matsusue, Eiji, Inoue, Chie, Matsumoto, Kensuke, Tanino, Tomohiko, Nakamura, Kazuhiko, Fujii, Shinya
• Format: Journal Article
• Language: English
• Published: Japan Tottori University Medical Press 2022; YAM
• Subjects: Original; cochlear modiolus; superficial siderosis; magnetic resonance imaging; SPGR; T1-shortening
• ISSN: 0513-5710; 1346-8049
• DOI: 10.33160/yam.2022.11.001

[ABSTRACT] [Background] Superficial siderosis (SS) results from chronic bleeding in the subarachnoid space. SS can be classified as infratentorial SS (i-SS) and supratentorial SS (s-SS). The cochlear modiolus (CM) normally shows low signal intensity (SI) on T1-weighted images (T1WI). We noticed persistently high SI of the CM on unenhanced thin-sliced T1WI in patients with i-SS. The purpose of this study was to evaluate the correlation between SS and high SI of the CM on unenhanced T1WI. [Methods] This retrospective study analyzed three cases with i-SS, eight cases with s-SS, and 23 normal controls (NC) evaluated on unenhanced thin-sliced T1WI with a three-dimensional spoiled gradient-recalled echo sequence. CM-T1SI scores of 0, 1, and 2 indicated low, iso, and high SI, respectively. In cases with scores of 2 evaluated several times, all scores were reviewed for each case. The CM-T1SI ratio was defined as the contrast ratio between the CM and the cerebellum. Differences between the three groups were statistically analyzed based on the CM-T1SI score and ratio. Receiver operative curve (ROC) analysis was used to determine the cut-off values for differentiating the i-SS group from the NC group based on the CM-T1SI ratio. [Results] Two patients with i-SS had a score of 2 on all evaluations. The CM-T1SI score and ratio differed significantly between the i-SS and NC groups. The accuracy of the CM-T1SI ratio for discriminating i-SS from NC was 98.9% at a cutoff value of 0.628. [Conclusion] High SI of the CM on unenhanced TIWI can be an additional characteristic finding of i-SS.