Subdivision of marker sites and summary of grading system
| Grade | Marker Sites | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Frontal Lobe | Temporal Lobe | Parietal Lobe | Peritrigonal Area | ||||||
| Pre-R | Polar | I–II | Lateral | Polar | Post-R | Gyri | Posterior | Superior | |
| 0 | − | − | − | − | − | − | − | − | − |
| 1 | + | − | − | + | − | + | − | + | − |
| 2 | + | + | − | + | + | + | + | + | + |
| 3 | + | + | + | ||||||
Note.—R indicates rolandic; I–II, first and second convolutions; +, presence of myelination (absence of T2 hyperintensity); −, absence of myelination (presence of T2 hyperintensity).