Detecting optic nerve lesions in multiple sclerosis patients with a 1,5 T MRI: Evaluation of a 3D DIR sequence compared to a 2D STIR sequence.

Objectives: Optic neuritis is a common clinical presentation in patients suffering from multiple sclerosis (MS). Even though optic neuritis is not part of the MS diagnostic criteria, the diagnosis and consideration of differential diagnoses are important in clinical routine. For the evaluation of the optic nerves with MRI, T2-weighted images with fat suppression, known as short tau inversion recovery sequences (STIR), are often used. Besides that, double inversion recovery (DIR) sequences are being used increasingly in MS patients, especially to determine cortical lesions. The Aim of this study was to evaluate the 3D-DIR for the detection of lesions in the optic nerves in MS patients.

Methods: MR examinations of 45 MS-patients containing both STIR and DIR images were independently assessed by two neuroradiologic experienced radiologists, blinded to clinical data. A third neuroradiologic, an experienced radiologist, evaluated the images together, also considering clinical data. These results were considered ground truth and statistically compared to the results of the single readings. To objectify our findings, ROI measurements of affected and unaffected optic nerve segments were made, and a contrast ratio (CR) was calculated.

Result: DIR images are statistically equivalent to STIR images concerning the detection of lesions in the optic nerve (p < 0.001). The sensitivity of DIR images (84.7 %) and STIR images (77 %), as well as the specificity (92.2 % and 91.2 %), are comparable. The interrater reliability was substantial for both sequences (κ = 0,73) as well as separated for the STIR images (κ = 0.744) and the DIR images (κ = 0.707). The objective analysis revealed significantly higher CRs in DIR images (p < 0.001).

Conclusion: 3D DIR images showed similar sensitivity and specificity for detecting optic nerve lesions in comparison to dedicated 2D images of the optic nerve. When 3D DIR images are part of the routine scan protocol for evaluating MS patients, additional 2D imaging of the optic nerve is no longer necessary.