Possible distinguishing criteria between SDHy and cSDH in neuroimaginga
| Criterion | SDHy | cSDH | Remarks |
|---|---|---|---|
| Neomembranes/septa/chamber formations | No | Yes | MRI more sensitive than CT |
| IV contrast may improve the detection of neomembranes | |||
| First formation of neomembranes macroscopically visible after ∼10 days;74 when using MR imaging contrast after ∼2–4 weeks22 | |||
| Late (chronifying) SDHys may also have first thin neomembranes (transitional phase to cSDH, terminologic gray zone) | |||
| Structure/composition | Rather homogeneous (CSF-like) | Rather heterogeneous/complex (evidence for blood products and CSF) | Heterogeneity of different cSDH fluid areas by neomembrane-associated chamber formations |
| Coexisting brain edema | Possible | Unlikely | Brain edema = rather acute/subacute |
| Growth behavior | At first, often rapidly progredient in growth; subsequently, mostly regredient in growth or static | Rather static/only slowly progredient in growth | Requires serial neuroimaging |
| Density | Very CSF-like, between 3.5 and 11.5 HU66 | Slightly higher density than CSF due to admixture of blood components, between 6.4 and 24.6 HU66 | Requires standardized measurements of densities |
| CSF = 5–10 HU | |||
| SDHHys with low blood fraction and high dilution with CSF are likely to show HU values just above 10 HU as well; thus, differentiation between SDHy and SDHHy may be difficult |
↵a According to Hedlund22 Wittschieber et al,27 Vezina,28 Zouros et al,29 Case,33 Bergström et al,66 and Walter et al.74