Accuracy of Unenhanced MRI in the Detection of New Brain Lesions in Multiple Sclerosis

Authors: Paul Eichinger, Simon Schön, Viola Pongratz, Hanni Wiestler, Haike Zhang, Matthias Bussas, Muna-Miriam Hoshi, Jan Kirschke, Achim Berthele, Claus Zimmer, Bernhard Hemmer, Mark Mühlau, Benedikt Wiestler


Background
Administration of a gadolinium-based contrast material is widely considered obligatory for follow-up imaging of patients with multiple sclerosis (MS). However, advances in MRI have substantially improved the sensitivity for detecting new or enlarged lesions in MS.

Purpose
To investigate whether the use of contrast material has an effect on the detection of new or enlarged MS lesions and, consequently, the assessment of interval progression.

Materials and Methods
In this retrospective study based on a local prospective observational cohort, 507 follow-up MR images obtained in 359 patients with MS (mean age, 38.2 years ± 10.3; 246 women, 113 men) were evaluated. With use of subtraction maps, nonenhanced images (double inversion recovery [DIR], fluid-attenuated inversion recovery [FLAIR]) and contrast material–enhanced (gadoterate meglumine, 0.1 mmol/kg) T1-weighted images were separately assessed for new or enlarged lesions in independent readings by two readers blinded to each other’s findings and to clinical information. Primary outcome was the percentage of new or enlarged lesions detected only on contrast-enhanced T1-weighted images and the assessment of interval progression. Interval progression was defined as at least one new or unequivocally enlarged lesion on follow-up MR images.

Results
Of 507 follow-up images, 264 showed interval progression, with a total of 1992 new or enlarged and 207 contrast-enhancing lesions. Four of these lesions (on three MR images) were retrospectively detected on only the nonenhanced images, corresponding to 1.9% (four of 207) of the enhancing and 0.2% (four of 1992) of all new or enlarged lesions. Nine enhancing lesions were not detected on FLAIR-based subtraction maps (nine of 1442, 0.6%). In none of the 507 images did the contrast-enhanced sequences reveal interval progression that was missed in the readouts of the nonenhanced sequences, with use of either DIR- or FLAIR-based subtraction maps. Interrater agreement was high for all three measures, with intraclass correlation coefficients of 0.91 with FLAIR, 0.94 with DIR, and 0.99 with contrast-enhanced T1-weighted imaging.

Conclusion
At 3.0 T, use of a gadolinium-based contrast agent at follow-up MRI did not change the diagnosis of interval disease progression in patients with multiple sclerosis.

© RSNA, 2019

See also the editorial by Saindane in this issue.

Summary
At 3.0 T, use of a gadolinium-based contrast material at follow-up MRI did not change the diagnosis of interval disease progression in patients with multiple sclerosis.

Key Points
In more than 500 follow-up images, only four of 1996 new or enlarged multiple sclerosis lesions would have been missed with 3.0-T MRI without the administration of contrast material.

With 3.0-T MRI, the assessment of interval progression did not differ between contrast-enhanced and nonenhanced images.