MRI appearance of chronic subdural hematoma

Abstract

Objective: We aimed to describe the magnetic resonance imaging (MRI) characteristics of chronic subdural hematoma (cSDH) and to ascribe MRI patterns.

Methods: A total of 20 patients having 27 subdural hematomas underwent contrast-enhanced (CE) MRI of the brain at our institution between April 2019 and May 2021. The images were independently evaluated by two experienced neuroradiologists with regard to imaging characteristics on T1w, T2w, T2^*-GRE, FLAIR, diffusion-weighted magnetic resonance imaging (DWI), and CE images.

Results: The signal characteristics of cSDH on T1- and T2-weighted images were rather heterogeneous. The majority of hematomas (74%) had internal septations. Surprisingly, contrast enhancement along the outer membrane adjacent to the cranium was noticed in all hematomas. There was also contrast enhancement along the inner membrane adjacent to the brain in more than one-third of the hematomas (37%). In approximately two-thirds of the cSDH (62%), there was a mass-like enhancement of the hematoma. Most hematomas (89%) were partially hypointense on T2^*-GRE and/or susceptibility-weighted imaging (SWI). Restricted diffusion was detected in approximately one-third of the hematomas (33%).

Conclusion: Consistent contrast enhancement along the outer membrane, triangular-shaped contrast enhancement at the borders of the cSDH, and infrequent enhancement of the inner membrane may help to distinguish cSDH from other entities such as empyema and tumors. Mass-like enhancement may refer to non-solid hematomas and could be an indicator for hematoma growth and a possible surrogate for successful endovascular embolization. Restricted diffusion in a subdural mass is not specific for empyema but may also be found in cSDH.

Keywords: chronic; empyema; hematoma; magnetic resonance imaging; subdural.

Figure 1

A 62-year-old male patient with chronic subdural hematoma (cSDH) over the left convexity. Axial T1w images pre (A) and post (B) contrast administration as well as an axial T2*w gradient echo image (C). There is enhancement of the inner [(B): thin arrow] and outer membrane [(B): arrow] as well as a roughly triangular, spandrel-like contrast enhancement at the borders of the hematoma [(B): arrowheads]. On T2*-GRE (C), there is hemosiderin staining adjacent to the dural surface and septa [(C): arrows].

Figure 2

A 66-year-old male patient with chronic subdural hematoma (cSDH) over the left convexity. Axial diffusion-weighted image (DWI) (A) and respective apparent diffusion coefficient (ADC) map (B), T1w image (C), and T2* gradient echo-weighted image (D). There are patchy areas of diffusion restriction within the hematoma [(A,B): arrows]. The hematoma is homogenously hyperintense on T1w images (C) and shows hemosiderin staining adjacent to the inner membrane and septa [(D): arrows] on T2*-GRE.

Figure 3

A 76-year-old female patient with bilateral chronic subdural hematomas (cSDHs). Axial-T2-FLAIR image (A), axial T1w images pre (B), post (C), and contrast administration as well as a sagittal T2w over the right hematoma (D). The hematomas are of mixed signal intensity on T2-FLAIR (A), T1w (B), as well as T2w images [(D): arrow]. There is enhancement of the inner [(C): thin arrows] and outer membrane [(C): arrows] as well as spandrel-like contrast enhancement at the borders of the hematoma [(C): arrowhead].

Figure 4

A 66-year-old female patient with chronic subdural hematoma (cSDH) over the left convexity. Axial T2-FLAIR images before (A) and after (B) contrast administration showing mass-like enhancement of the hematoma [(B): arrow].