Quantitative measurement of blood flow in paediatric brain tumours-a comparative study of dynamic susceptibility contrast and multi time-point arterial spin labelled MRI.

Rishma Vidyasagar,Laura M Parkes,Laurence Abernethy,Barry Pizer,Shivaram Avula

doi:10.1259/bjr.20150624

Abstract

Objective:Arterial spin-labelling (ASL) MRI uses intrinsic blood water to quantify the cerebral blood flow (CBF), removing the need for the injection of a gadolinium-based contrast agent used for conventional perfusion imaging such as dynamic susceptibility contrast (DSC). Owing to the non-invasive nature of the technique, ASL is an attractive option for use in paediatric patients. This work compared DSC and multi-timepoint ASL measures of CBF in paediatric brain tumours.Methods:Patients (n = 23; 20 low-grade tumours and 3 high-grade tumours) had DSC and multi-timepoint ASL with and without vascular crushers (VC). VC removes the contribution from larger vessel blood flow. Mean perfusion metrics were extracted from control and T1-enhanced tumour regions of interest (ROIs): arterial arrival time (AAT) and CBF from the ASL images with and without VC, relative cerebral blood flow (rCBF), relative cerebral blood volume, delay time (DT) and mean transit time (MTT) from the DSC images.Results:Significant correlations existed for: AAT and DT (r = 0.77, p = 0.0002) and CBF and rCBF (r = 0.56, p = 0.02) in control ROIs for ASL-noVC. No significant correlations existed between DSC and ASL measures in the tumour region. Significant differences between control and tumour ROI were found for MTT (p < 0.001) and rCBF (p < 0.005) measures.Conclusion:Significant correlations between ASL-noVC and DSC measures in the normal brain suggest that DSC is most sensitive to macrovascular blood flow. The absence of significant correlations within the tumour ROI suggests that ASL is sensitive to different physiological mechanisms compared with DSC measures.Advances in knowledge:ASL provides information which is comparable with that of DSC in healthy tissues, but appears to reflect a different physiology in tumour tissues.

Highlights

Central nervous system tumours are the most common group of solid tumours in childhood and comprise 20–25% of all childhood neoplasms
No significant differences were noted from the Arterial spin-labelling (ASL) measures in the tumour region when compared with the control region
When considering the measures derived from dynamic susceptibility contrast (DSC), mean transit time (MTT) and relative cerebral blood flow (rCBF) were both significantly (p, 0.001) lower within the tumour region than within the control region; rCBV did not show a significant difference

Summary

Introduction

Central nervous system tumours are the most common group of solid tumours in childhood and comprise 20–25% of all childhood neoplasms. Some types of brain tumours may be completely resected, many cannot be completely removed without serious morbidity. Survivors of central nervous system tumours are frequently susceptible to severe and sometimes devastating neuropsychological, neurological and other pathologies, which may be related to factors such as the tumour location and therapy used. Brain imaging is fundamental to the management of brain tumours, and there is a clear need for the development of improved non-invasive measures of tumour characteristics. The potential benefits of using a noninvasive method to monitor paediatric brain tumour (PBT) progression and response to treatment are reduced distress to patients and increased frequency of monitoring, which may improve treatment plans and possibly lead to better patient outcomes

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Conclusion