Cerebral and tumoral blood flow in adult gliomas: a systematic review of results from magnetic resonance imaging

OBJECTIVE: Blood flow is the rate of blood movement and relevant to numerous processes, though understudied in gliomas. The aim of this review was to pool blood flow metrics obtained from MRI modalities in adult supratentorial gliomas. METHODS: MEDLINE, EMBASE and the Cochrane database were queried 01/01/2000–31/12/2019. Studies measuring blood flow in adult Grade II–IV supratentorial gliomas using dynamic susceptibility contrast (DSC) MRI, dynamic contrast enhanced MRI (DCE-MRI) or arterial spin labelling (ASL) were included. Absolute and relative cerebral blood flow (CBF), peritumoral blood flow and tumoral blood flow (TBF) were reported. RESULTS: 34 studies were included with 1415 patients and 1460 scans. The mean age was 52.4 ± 7.3 years. Most patients had glioblastoma (n = 880, 64.6%). The most common imaging modality was ASL (n = 765, 52.4%) followed by DSC (n = 538, 36.8%). Most studies were performed pre-operatively (n = 1268, 86.8%). With increasing glioma grade (II vs IV), TBF increased (70.8 vs 145.5 ml/100 g/min, p < 0.001) and CBF decreased (85.3 vs 49.6 ml/100 g/min, p < 0.001). In Grade IV gliomas, following treatment, CBF increased in ipsilateral (24.9 ± 1.2 vs 26.1 ± 0.0 ml/100 g/min, p < 0.001) and contralateral white matter (25.6 ± 0.2 vs 26.0± 0.0 ml/100 g/min, p < 0.001). CONCLUSION: Our findings demonstrate that increased mass effect from high-grade gliomas impairs blood flow within the surrounding brain that can improve with surgery. ADVANCES IN KNOWLEDGE: This systematic review demonstrates how mass effect from brain tumours impairs blood flow in the surrounding brain parenchyma that can improve with treatment

Kinetic modelling of [(11)C]PBR28 for 18 kDa translocator protein PET data:A validation study of vascular modelling in the brain using XBD173 and tissue analysis

The 18 kDa translocator protein (TSPO) is a marker of microglia activation in the central nervous system and represents the main target of radiotracers for the in vivo quantification of neuroinflammation with positron emission tomography (PET). TSPO PET is methodologically challenging given the heterogeneous distribution of TSPO in blood and brain. Our previous studies with the TSPO tracers [11C]PBR28 and [11C]PK11195 demonstrated that a model accounting for TSPO binding to the endothelium improves the quantification of PET data. Here, we performed a validation of the kinetic model with the additional endothelial compartment through a displacement study. Seven subjects with schizophrenia, all high-affinity binders, underwent two [11C]PBR28 PET scans before and after oral administration of 90 mg of the TSPO ligand XBD173. The addition of the endothelial component provided a signal compartmentalization much more consistent with the underlying biology, as only in this model, the blocking study produced the expected reduction in the tracer concentration of the specific tissue compartment, whereas the non-displaceable compartment remained unchanged. In addition, we also studied TSPO expression in vessels using 3D reconstructions of histological data of frontal lobe and cerebellum, demonstrating that TSPO positive vessels account for 30% of the vascular volume in cortical and white matter

The LEGATOS technique: A new tissue‐validated dynamic contrast‐enhanced MRI method for whole‐brain, high‐spatial resolution parametric mapping

From Wiley via Jisc Publications RouterHistory: received 2020-06-30, rev-recd 2021-04-23, accepted 2021-04-24, pub-electronic 2021-05-15Article version: VoRPublication status: PublishedFunder: Dowager Countess Eleanor Peel Trust; Id: http://dx.doi.org/10.13039/501100000832Funder: Cancer Research UK; Id: http://dx.doi.org/10.13039/501100000289; Grant(s): C8742/A18097Purpose: A DCE‐MRI technique that can provide both high spatiotemporal resolution and whole‐brain coverage for quantitative microvascular analysis is highly desirable but currently challenging to achieve. In this study, we sought to develop and validate a novel dual‐temporal resolution (DTR) DCE‐MRI‐based methodology for deriving accurate, whole‐brain high‐spatial resolution microvascular parameters. Methods: Dual injection DTR DCE‐MRI was performed and composite high‐temporal and high‐spatial resolution tissue gadolinium‐based‐contrast agent (GBCA) concentration curves were constructed. The high‐temporal but low‐spatial resolution first‐pass GBCA concentration curves were then reconstructed pixel‐by‐pixel to higher spatial resolution using a process we call LEGATOS. The accuracy of kinetic parameters (Ktrans, vp, and ve) derived using LEGATOS was evaluated through simulations and in vivo studies in 17 patients with vestibular schwannoma (VS) and 13 patients with glioblastoma (GBM). Tissue from 15 tumors (VS) was examined with markers for microvessels (CD31) and cell density (hematoxylin and eosin [H&E]). Results: LEGATOS derived parameter maps offered superior spatial resolution and improved parameter accuracy compared to the use of high‐temporal resolution data alone, provided superior discrimination of plasma volume and vascular leakage effects compared to other high‐spatial resolution approaches, and correlated with tissue markers of vascularity (P ≤ 0.003) and cell density (P ≤ 0.006). Conclusion: The LEGATOS method can be used to generate accurate, high‐spatial resolution microvascular parameter estimates from DCE‐MRI

Sex Differences in Biomarkers for Predicting Cardiovascular and Coronary Events

INTRODUCTION: Primary and secondary prevention of cardiovascular Disease (CVD) are major concerns and priorities. The best tools that we actually have to prevent CVD are the biomarkers. Numerous studies have shown that the presentation of cardiac disease in women is quite different from the presentation in men. Thus, one question arises "Are there any differences in biomarkers as well?" The answer to this question could open new avenues for a tailored management of cardiac diseases. METHOD AND RESULTS: We searched the PubMed and Medline databases for articles comparing differences between the 2 genders in terms of biomarker expression. Keywords used included "Cardiovascular biomarkers sex differences". We reviewed the role of different biomarkers in the 2 genders in relation to cardiac events. CONCLUSIONS: Differences of expressions in biomarker levels were found between the 2 genders. Further investigation should be promoted