The relationship of contrast-enhanced lesions with radiological variables in multiple sclerosis patients

Introduction and Aim:Gadolinium enhanced MRI is routinely used for follow-up of patients with multiple sclerosis.Our aim is to determine the relationship of 'contrast-enhanced plaques', which is an indicator of acute attack in MS, with radiological parameters and to evaluate the diagnostic necessity of using contrast media in the follow-up of patients with stable lesion burden. Material and Method: We retrospectively a total of 412 consecutive MRIs in 300 adult patients who were diagnosed with MS at Akdeniz University, NeurologyDepartment. Each enhancing lesion, accompanying signal change in FLAIR, and the course of the lesions (complete regression, partial regression, and stable) were recorded. The lesion burden was classified as mild (less than 10), moderate (11-20), and severe (more than 20). If the patient completed more than one control during this period, it was evaluated in 3D FLAIR and postcontrast sequences for new lesion development. It was evaluated if the enhanced lesions were newly appeared on the T2/FLAIR sequence or changed in size. Reenhancement was defined as the onset of enhancement without increasing the size of a pre-existing lesion.The clinical presentations of the patients were recorded for each examination, and MRI were obtained recently within 3 weeks for the patients with acute attack. The data were analyzed using SPSS (IBM SPSS for Windows, ver.23) statistical package program. Descriptive statistics for continuous variables in the study; Expressed as Average, Standard Deviation, Minimum and Maximum; expressed as Number (n) and Percentage (%) for categorical variables. Kolmogorov-Smirnov and Skewness-Kurtosis tests were used to check the conformity of the data to the normal distribution. In cases where parametric test assumptipons were met, the T test was used to compare the continuous variables of two independent groups. Otherwise the Mann-Whitney U test was used. "One-Way Analysis of Variance (ANOVA)" was performed to compare the continuos variables of more than two indepedent groups, in cases where the parametric test assumptions were met.Otherwise the Kruskal-Wallis Test was performed. Chi-square test was used to determine the relationship between categorical variables. The statistical significance level (P) was taken as 5% in the calculations. Results: A total of 300 patients participated in the study. The mean age of the study group was 39,0 ± 11,9.204 patients had only 1 MRI, 82 patients had 2, 12 patients had 3 and 2 patients had 4 MRI scans. There was no positive neurologic examination finding in 314 applications (76.2%), acute attack was present in 98 applications (23.8%). The lesion burden was mild in 142 (47.3%), moderate in 82 (27.3%), and high in 76 (25.3%) patients. A total of 60 of 412 MRIs demonstrated 141 enhancing lesions, of which 140 (99,3%) had corresponding hyperintensity on FLAIR. 4 of the contrast-enhanced lesions were pre-existing and showed increased size on T2/FLAIR sequences. Three of the lesions were in the same patient, accompanied by newly enhanced lesions and an increase in lesion load. Only 2 enhanced lesions were observed as reenhancement, and an increase in the total lesion burden was accompanied in one of these patients.A total of 17 (15%) of the 112 MRIs with a prior comparision had imaging evidence of disease progression. 1 MRIs with progression was detectable only on postcontrast T1 images. A statistically significant difference was observed in the "clinical presentation" and "existence of contrast-enhanced-lesions" (p<0.05). A statistically significant difference was observed in "lesion burden" and "enhancing lesions" (p<0.05). In other words, enhancing lesions were frequently observed in 'patients with high-lesions burdens' als 'with low burdens'. Conclusion: Patients with MS routinely have MR imaging with contrast every 6-12 months to assess the progression. Previously tissue deposition of gadolinium-based contrast agents is revealed in multiple studies Hence, the long-term safety of these agent is questioned. In the literature, there are many studies which questioned the necessarity of use of contrast agent in nonprogressive MS patiens.In our study, we have obtained results that are correlated with other studies in the literature. Because nearly all enhancing lesions are associated with a change in signal or size on unenhanced imaging (93,1%), and progresion was only evident in 15% of patients, it is reasonable to consider reserving contrast for only those patients with evidence of progression on precontrast MR images. Keywords: Multiple Sclerosis, Gadolinium-based Contrast Agent, Enhancing Lesions, Magnetic Resonance Imaging