Table 1.
Demographics of MS patients.
Table 2.
Proposed histopathologic interpretation based upon signal intensity patterns on MR images.
Fig 1.
Schematic sketches for lesions depicting ideal signal intensity distribution on images.
The ideal signal intensity distribution on GRE-T2* weighted image, SWI and QSM for Pattern A to D lesions are shown. Pattern A and B lesions belong to non-iron related pathology, whereas Pattern C (nodular) and D (ring-like) lesions are associated with iron-enriched pathology.
Fig 2.
Distribution of total number of lesions at baseline and at follow-up period.
Bar diagram showing the variations in the number of baseline lesions (n = 191) of each pattern (A-D) between baseline (gray-color) and follow-up period (black-color).
Fig 3.
Pattern switch from non-iron related pathology at baseline to iron related pathology at follow-up.
In the upper rows, axial GRE-T2* weighted image shows a hyperintense lesion (arrow) that appears isointense on SWI and QSM consistent with Pattern A at baseline. This lesion exhibited hypointensity on SWI and hyperintensity on QSM (lower rows) at follow-up indicating iron accumulation. Hence this lesion switched from Pattern A at baseline to Pattern C after 2 years of follow up.
Fig 4.
No change in pattern B lesion and appearance of new iron-laden lesions at follow-up.
In the upper rows, axial GRE-T2* weighted image shows a hyperintense lesion (green arrow) that appears isointense on SWI and hyperintense on QSM consistent with Pattern B at baseline. This lesion showed similar signal intensity pattern on images (lower rows) at follow-up suggesting this lesion remained as Pattern B at follow-up during a period of 2.5 years. Additionally, two lesions that were not visible at baseline, became visible at follow-up. Incidentally, both of these lesions demonstrated nodular hypointense signals on GRE-T2* and SWI (yellow arrows) and hyperintense signal on QSM (yellow arrows) consistent with Pattern C.
Fig 5.
Redistribution of signal intensity pattern in iron-laden lesions at follow-up relative to baseline.
In the upper left panel, QSM shows solid hyperintense signal within a lesion indicating iron-laden nodular lesion (Pattern C) at baseline. This lesion underwent redistribution of signal intensity from nodular to ring-like (Pattern D) on QSM (lower left panel) at follow-up. In the upper right panel, QSM shows ring-like hyperintense signal within another lesion consistent with Pattern D at baseline that underwent redistribution of signal intensity from ring-like to nodular (Pattern C) on QSM (lower right panel) at follow-up.
Fig 6.
Distribution of QSM from iron-laden lesions at baseline and at follow-up period.
Box-and-whisker plots demonstrating the distribution of QSM from iron-laden (Pattern C and Pattern D) lesions at baseline (white) and at follow-up (shaded). The bottom and top edges of boxes represent the 25th percentile, and the 75th percentile values. The bands within the boxes represents 50th percentile (median). Whiskers display the range of data distribution. Non-significant (p>0.05) increase in QSM at follow-up relative to baseline was observed from these lesions.
Table 3.
Distribution of iron-laden and non-iron-laden lesions at baseline, pattern switch and formation of new lesions by disease type.