Remote brain microhaemorrhages may predict haematoma in glioma patients treated with radiation therapy

An update on susceptibility-weighted imaging in brain gliomas

Susceptibility-weighted imaging (SWI) has become a standard component of most brain MRI protocols. While traditionally used for detecting and characterising brain hemorrhages typically associated with stroke or trauma, SWI has also shown promising results in glioma assessment. Numerous studies have highlighted SWI's role in differentiating gliomas from other brain lesions, such as primary central nervous system lymphomas or metastases. Additionally, SWI aids radiologists in non-invasively grading gliomas and predicting their phenotypic profiles. Various researchers have suggested incorporating SWI as an adjunct sequence for predicting treatment response and for post-treatment monitoring. A significant focus of these studies is on the detection of intratumoural susceptibility signals (ITSSs) in gliomas, which are indicative of microhemorrhages and vessels within the tumour. The quantity, distribution, and characteristics of these ITSSs can provide radiologists with more precise information for evaluating and characterising gliomas. Furthermore, the potential benefits and added value of performing SWI after the administration of gadolinium-based contrast agents (GBCAs) have been explored. This review offers a comprehensive, educational, and practical overview of the potential applications and future directions of SWI in the context of glioma assessment. CLINICAL RELEVANCE STATEMENT: SWI has proven effective in evaluating gliomas, especially through assessing intratumoural susceptibility signal changes, and is becoming a promising, easily integrated tool in MRI protocols for both pre- and post-treatment assessments. KEY POINTS: • Susceptibility-weighted imaging is the most sensitive sequence for detecting blood and calcium inside brain lesions. • This sequence, acquired with and without gadolinium, helps with glioma diagnosis, characterisation, and grading through the detection of intratumoural susceptibility signals. • There are ongoing challenges that must be faced to clarify the role of susceptibility-weighted imaging for glioma assessment.

Review of Cerebral Radiotherapy-Induced Vasculopathy in Pediatric and Adult Patients

Radiation therapy (RT) causes radiation-induced vasculopathy, which requires clinicians to identify and manage this side effect in pediatric and adult patients. This article reviews previous findings about the pathophysiology of RT-induced vascular injury, including endothelial cell injury, oxidative stress, inflammatory cytokines, angiogenic pathways, and remodeling. The vasculopathy is categorized into ischemic vasculopathy, hemorrhagic vasculopathy, carotid artery injury, and other malformations (cavernous malformations and aneurysms) in populations of pediatric and adult patients separately. The prevention and management of this RT-induced side effect are also discussed. The article summarizes the distribution and risk factors of different types of RT-induced vasculopathy. This will help clinicians identify high-risk patients with corresponding vasculopathy subtypes to deduce prevention and treatment strategies accordingly.

Susceptibility-weighted imaging cannot distinguish radionecrosis from recurrence in brain metastases after radiotherapy: a comparison with high-grade gliomas

AIM

To explore the efficiency of susceptibility-weighted imaging (SWI) in the differential diagnosis of recurrence from radionecrosis in brain metastases (BM) and in high-grade gliomas (HGG).

MATERIALS AND METHODS

From September 2016 to November 2018, 56 patients with BM and 42 patients with HGG were included in this retrospective study. BM and HGG were assigned to the recurrence and radionecrosis groups according to their histopathology or follow-up results. The proportion of dark signal intensity (proDSI), which was defined as the area of dark signal on SWI or the enhancing area on contrast-enhanced T1-weighted imaging (T1WI), was calculated for each patient. Analysis of variance (ANOVA) with Tukey's honestly significant difference test was used for the repeat multiple comparisons. Receiver operating characteristic curve analysis was performed to validate the diagnostic performance.

RESULTS

For HGG, the proDSI in the recurrence group was significantly lower than that in the radionecrosis group (0.13 ± 0.05 versus 0.43 ± 0.11, p<0.001); however, for BM, no statistical difference was found between groups (0.49 ± 0.09 versus 0.46 ± 0.08, p=0.26). proDSI had the best diagnostic performance (AUC = 0.87, 95% CI: 0.76-0.98; sensitivity = 0.87; specificity = 0.88) for HGG, when a cut-off value of 0.21 was selected.

CONCLUSIONS

Semi-quantitative analysis using SWI is feasible for the differential diagnosis between recurrence and radionecrosis in HGG, but is not feasible in BM. Semi-quantitative assessment based on SWI should interpreted with caution in BM after radiotherapy in clinical practice.