PURPOSE: In patients with multiple sclerosis (MS), Double Inversion Recovery 
(DIR) magnetic resonance imaging (MRI) can be used to identify cortical lesions 
(CL). We sought to evaluate the reliability of CL detection on DIR 
longitudinally at multiple subsequent time-points applying the MAGNIMs scoring 
criteria for CLs.
METHODS: 26 MS patients received a 3T-MRI (Siemens, Skyra) with DIR at 12 
time-points (TP) within a 16 months period. Scans were assessed in random order 
by two different raters. Both raters separately marked all CLs on each scan and 
total lesion numbers were obtained for each scan-TP and patient. After a 
retrospective re-evaluation, the number of consensus CLs (conL) was defined as 
the total number of CLs, which both raters finally agreed on. CLs volumes, 
relative signal intensities and CLs localizations were determined. Both ratings 
(conL vs. non-consensus scoring) were compared for further analysis.
RESULTS: A total number of n = 334 CLs were identified by both raters in 26 MS 
patients with a first agreement of both raters on 160 out of 334 of the CLs 
found (κ = 0.48). After the retrospective re-evaluation, consensus agreement 
increased to 233 out of 334 CL (κ = 0.69). 93.8% of conL were visible in at 
least 2 consecutive TP. 74.7% of the conL were visible in all 12 consecutive TP. 
ConL had greater mean lesion volumes and higher mean signal intensities compared 
to lesions that were only detected by one of the raters (p<0.05). A higher 
number of CLs in the frontal, parietal, temporal and occipital lobe were 
identified by both raters than the number of those only identified by one of the 
raters (p<0.05).
CONCLUSIONS: After a first assessment, slightly less than a half of the CL were 
considered as reliably detectable on longitudinal DIR images. A retrospective 
re-evaluation notably increased the consensus agreement. However, this finding 
is narrowed, considering the fact that retrospective evaluation steps might not 
be practicable in clinical routine. Lesions that were not reliably identifiable 
by both raters seem to be characterized by lower signal intensity and smaller 
size, or located in distinct anatomical brain regions.