Related Experiment Video
Updated: May 25, 2026
Sub-acute Cerebral Microhemorrhages Induced by Lipopolysaccharide Injection in Rats
Published on: October 17, 2018
Detection of microhemorrhage in posterior reversible encephalopathy syndrome using susceptibility-weighted imaging
A M McKinney1, B Sarikaya, C Gustafson
1Department of Radiology, University of Minnesota, MMC 292, 420 Delaware St SE, Minneapolis, MN 55455, USA. mckinrad@umn.edu
Background And Purpose:
PRES-related vasogenic edema is potentially reversible while hemorrhage occurs in only 15.2%-17.3% of patients. However, the true incidence of hemorrhage could be higher when SWI is considered. Thus, we set out to determine the incidence of MH, SAH, and IPH in PRES by using SWI and to particularly evaluate whether such MHs are reversible.
Materials And Methods:
Thirty-one patients with PRES and SWI were included, 17 having follow-up SWI. Two neuroradiologists reviewed SWI, FLAIR, DWI, and CE-T1WI. The presence and number of MHs (<5 mm) on SWI, SAH, and IPH (>5 mm) were recorded at presentation and follow-up. We evaluated associations between the presence of MH on SWI and DWI lesions, SAH, IPH, contrast enhancement, and MR imaging severity.
Results:
Hemorrhage was present in 20/31 patients (64.5%), with MHs on SWI in 18/31 (58.1%) at presentation and in 11/17 (64.7%) at follow-up. SAH was present in 3/31 on SWI and 4/31 on FLAIR, while 2/31 had IPH. At follow-up, no patients had acquired new MHs; 2/5 MHs in 1 patient resolved. Four patients with available SWI before PRES developed MHs after PRES onset. No association was found between the presence of MHs on SWI and DWI, SAH, IPH, enhancement, and MR imaging severity (all P > .05).
Conclusions:
SWI showed a higher rate of MH than previously described, underscoring the potential of SWI in evaluating PRES. Such MHs typically persist and may develop after PRES onset. However, the clinical relevance of MHs in PRES is yet to be determined. We propose that MHs in PRES relate to endothelial cell dysfunction.
Insights
Hemorrhage in PRES is common, with susceptibility-weighted imaging (SWI) revealing microhemorrhages (MHs) in over half of patients. These MHs often persist and can even develop after PRES onset, suggesting a link to endothelial dysfunction.
Area of Science:
- Neuroradiology
- Neuroimaging
- Vascular Neurology
Background:
- Posterior reversible encephalopathy syndrome (PRES) is characterized by vasogenic edema, typically reversible.
- Hemorrhage incidence in PRES is traditionally reported as low (15.2%-17.3%), but may be underestimated.
- Susceptibility-weighted imaging (SWI) may improve the detection of hemorrhage in PRES.
Purpose of the Study:
- To determine the incidence of microhemorrhages (MHs), subarachnoid hemorrhage (SAH), and intraparenchymal hemorrhage (IPH) in PRES using SWI.
- To evaluate the reversibility of MHs detected by SWI in PRES patients.
- To explore associations between MHs and other imaging findings in PRES.
Main Methods:
- Retrospective review of SWI, FLAIR, DWI, and CE-T1WI in 31 patients with PRES.
- Two neuroradiologists assessed the presence and number of MHs (<5 mm), SAH, and IPH (>5 mm) at presentation and follow-up (17 patients).
- Evaluation of associations between MHs and DWI lesions, SAH, IPH, contrast enhancement, and MR imaging severity.
Main Results:
- Hemorrhage was present in 64.5% of patients; MHs on SWI were detected in 58.1% at presentation and 64.7% at follow-up.
- SAH and IPH were less common (3/31 and 2/31, respectively).
- MHs typically persisted, with no new MHs acquired; 2/5 MHs resolved in one patient. Four patients developed MHs after PRES onset. No significant associations were found between MHs and other imaging findings.
Conclusions:
- SWI reveals a higher incidence of MHs in PRES than previously reported, highlighting its utility in evaluating the condition.
- MHs in PRES tend to be persistent and can develop post-onset, suggesting a potential link to endothelial cell dysfunction.
- The clinical significance of MHs in PRES requires further investigation.