From the Guidelines
Contrast is not necessary for detecting Posterior Reversible Encephalopathy Syndrome (PRES) on brain MRI. The diagnosis of PRES can typically be made using non-contrast T2-weighted and FLAIR (Fluid-Attenuated Inversion Recovery) sequences, which show characteristic vasogenic edema predominantly in the posterior cerebral regions, particularly the parietal and occipital lobes. According to the American College of Radiology 1, noncontrast MRI examinations of the brain are usually sufficient in the assessment of intracranial complications related to hypertensive emergency, including posterior reversible encephalopathy syndrome.
Some key points to consider when evaluating PRES with MRI include:
- The hallmark findings of PRES are visible on non-contrast sequences, such as T2-weighted and FLAIR images 1.
- Contrast-enhanced MRI may be performed if intracranial infection, tumor, inflammatory lesions, or vascular pathologies are suspected, but it is not necessary for the diagnosis of PRES 1.
- The pathophysiology of PRES involves disruption of the blood-brain barrier and autoregulatory mechanisms, leading to vasogenic edema that is best visualized on T2-weighted and FLAIR sequences.
- Diffusion-weighted imaging (DWI) is also useful to distinguish PRES from acute ischemic stroke, as PRES typically does not show restricted diffusion unless there is secondary infarction.
In clinical practice, the use of non-contrast MRI for the diagnosis of PRES is supported by the American College of Radiology 1, and it is essential to prioritize the patient's safety and avoid unnecessary contrast administration.
From the Research
Detection of PRES with Brain MRI
- The detection of Posterior Reversible Encephalopathy Syndrome (PRES) using Brain MRI has been studied in several research papers 2, 3, 4.
- According to these studies, conventional MRI and diffusion-weighted imaging (DWI) can be used to establish the diagnosis of PRES.
- The use of contrast agents in MRI for detecting PRES is not explicitly mentioned in these studies, but it is mentioned that DWI can be a useful complement to MRI in the diagnosis of PRES 2.
- In another study, it is mentioned that gadolinium-based contrast agents (GBCAs) have contraindications, and DWI can detect diffusion alterations in active inflammatory lesions, but this study is related to multiple sclerosis, not PRES 5.
- However, a study on the role of MRI in diagnosing local recurrence from rectal cancer found that the addition of gadolinium-enhanced MRI and diffusion-weighted imaging (DWI) improves T2 sequence performance for diagnosis, but this is not directly related to PRES 6.
Use of Contrast in Brain MRI for PRES
- There is no direct evidence in the provided studies that contrast is needed with a Brain MRI to detect PRES.
- The studies suggest that conventional MRI and DWI can be used to diagnose PRES, but they do not explicitly state whether contrast is necessary or not 2, 3, 4.
- More research may be needed to determine the role of contrast in Brain MRI for detecting PRES.