Comparison of the diagnostic performances of routine imaging protocol, three- dimensional contrast enhanced FLAIR and three- dimensional T1 black blood sequences in detecting active lesions in patients diagnosed with multiple sclerosis

Background and purpose: Multiple sclerosis (MS) is a demyelinating, autoimmune, neurodegenerative central nervous system (CNS) disease that is estimated to affect approximately 2.8 million people worldwide. In standard clinical protocols, contrast-enhanced MRI frequently uses the three-dimensional (3D) T1-weighted (T1W) MPRAGE sequence. Standard protocols have limited predictive power in the course of MS. Increased diagnostic performance in imaging of patients with clinically isolated syndrome (CIS) and consequently early diagnosis may be beneficial in long-term treatment evaluation. The aim of this study is to compare the diagnostic performances of three-dimensional T1 MPRAGE, three-dimensional T1-weighted black-blood, and three-dimensional contrast-enhanced FLAIR sequences for the detection of active MS lesions during acute attacks in patients with relapsing-remitting multiple sclerosis (RRMS). Materials and Methods: This single-center, prospective study was conducted at Afyonkarahisar Health Sciences University Hospital. Between August 2024 and April 2025, RRMS patients over 18 years old who presented to the neurology outpatient clinic and were suspected of having an acute attack were prospectively screened, and their images in the PACS system were examined. For the 48 patients who met the inclusion criteria and were within the appropriate age range during the specified period, measurements were taken for quantitative analysis of diagnostic performance, including calculations of SNR and CNR, lesion size, contrast enhancement pattern, lesion localization, active lesion ROI, normal-appearing white matter ROI, and background noise ROI. Statistical analysis was performed using SPSS 26.0. Bland-Altman analyses, Friedman and Wilcoxon Signed Ranks tests, Spearman correlation analyses, and Chi-square tests were conducted, with p<0.05 considered statistically significant. Results: The mean age of the female participants was 30.64 ± 9.25 years, while the mean age for male participants was 38.00 ± 9.38 years. Bland-Altman analyses evaluating the agreement between the same measurement types in different protocols showed that most measurements fell within the 95% confidence interval. No significant association was found between lesion location and contrast enhancement pattern. Four types of contrast enhancement patterns were defined in the study, with nodular (45.8%) and open ring (35.4%) being the most common. Peripheral (ring-like) enhancement was less frequent (16.7%), and heterogeneous enhancement was the least observed pattern (2.1%). Significant differences were found among the three imaging protocols in terms of AL ROI, NGBC ROI, and SNR values (p < 0.001). The T1 BB protocol provided the best contrast-to-noise ratio, and no significant difference was found between T1 MPRAGE and FLAIR CE (p = 0.083). A very strong positive correlation was observed between SNR and CNR across all protocols. AL ROI showed a strong positive correlation with both CNR and SNR in all three protocols. A negative correlation was observed between APG ROI and SNR and CNR values. Conclusion: In terms of SNR and CNR, the 3D T1 BB protocol was evaluated as the most successful. However, limitations include the single-observer design, the small number of patients, and the single-center nature of the study. There is a need for multi-center studies with larger sample sizes on the subject. Keywords: FLAIR, Magnetic Resonance Imaging, MPRAGE, Multiple Sclerosis, T1 Dark Blood