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Background: This study investigates the use of fibre tractography to facilitate visualisation of the medial longitudinal fasciculus (MLF) and the impact of internuclear ophthalmoplegia (INO) causing lesions on these reconstructions of the tract. Improved visualisation of such tracts may improve knowledge, understanding and confidence related to neurological conditions., Aims: To explore the use of fibre tractography for the visualisation of the MLF in patients with INO., Methods: Twelve MS subjects with clinical evidence of INO and 12 matched controls underwent magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI), of the brain. Fibre tractography reconstructions were then evaluated and validated by an experienced neuroanatomist., Results: The evaluating neuroanatomist confirmed that the MLF had been reproduced in all of the reconstructed cases (fibre tractography was unsuccessful in five cases). The sensitivity of fibre tractography to MLF pathology was 58.3 % while the specificity was much higher at 85.7 % with a positive predictive value of 87.5 % and a negative predictive value of 54.6 %, with excellent intra-reader reliability., Conclusion: This study demonstrates that fibre tractography of the MLF can potentially be performed with a view to facilitating improved visualisation of the tract and associated pathology in cases of INO. This may help explain the association between lesion type and location with clinical symptomatology and may assist in monitoring disease progression. These reconstructions may provide a valuable addition to the teaching and understanding of clinical signs related to subtle pathology.

Purpose: The purpose of this study was to investigate the diagnostic efficacy of a range of conventional magnetic resonance imaging (MRI) pulse sequences in the identification of internuclear ophthalmoplegia (INO) caused by medial longitudinal fasciculus (MLF) lesions in multiple sclerosis patients using a receiver-operating characteristic (ROC) methodology., Methods: A total of 15 clinically confirmed INO and 15 control subjects underwent conventional MRI at 1.5 T consisting of T2-weighted, proton density (PD)-weighted, and fluid-attenuated inversion recovery (FLAIR) sequences, following full institutional approval. A free-response, multiple-reader multiple-case design ROC study was used to evaluate the diagnostic efficacy of each sequence. All imaging sequences were evaluated by 10 board-certified neuroradiologists. Area under the curve (AUC), sensitivity, and specificity were analysed statistically for all three pulse sequences using repeated-measures analyses of variance and post-test analysis using Bonferroni's multiple comparison test of differences., Results: No significant AUC differences were found between the three sequences (p = 0.0697), with T2 recording the highest AUC (0.8346). Sensitivity differences between PD (0.7927) and FLAIR (0.6329) were significant (p < 0.05). Non-significant differences were also evident between T2 and FLAIR (p = 0.0511). The specificity analysis revealed an overall difference (p = 0.0005), with specific inter-sequence differences shown between T2 and PD (p < 0.05) and PD and FLAIR (p < 0.001) with the PD values being lower than those provided with the other two sequences., Conclusion: T2-weighted axial imaging through the MLF region resulted in the greatest overall diagnostic efficacy when viewing a combination of mean AUC, sensitivity, and specificity, in terms of the identification of INO-causing lesions.