Correlation between three-dimensional arterial spin labelling perfusion parameters and microvessel density in brain tumours: a prospective study

Abstract Background Brain perfusion imaging is a radiological technique used to study cerebral microvasculature. One type of magnetic resonance imaging (MRI) perfusion is arterial spin labelling (ASL), which has been utilised in the pre-operative evaluation of brain tumours. Microvessel density (MVD) is an important histological feature that influences the behaviour of brain tumours. In this study, we aimed to investigate whether there is a positive correlation between the perfusion of brain tumours, as measured by ASL and MVD, as assessed by histopathology using CD34 immunohistochemistry, irrespective of the tumour’s location within the brain. Patients and methods This study included 37 patients who were newly diagnosed with primary brain tumours. Patients with recurrent brain tumours or metastases and those who previously received chemotherapy or radiotherapy were excluded from the study. All patients underwent pre-operative evaluation by ASL, calculating both mean tumour blood flow (mTBF) directly within the lesion and relative tumour blood flow (rTBF) by normalising the perfusion of the lesion to the contralateral cortical grey matter using a standard 50 mm 2 ROI. The tumour MVD was evaluated by histopathology following either operative excision of the lesion or stereotactic biopsy using the CD34 immune marker. Results There was a statistically significant positive correlation between rTBF and MVD ( p -value = 0.001, r = 0.742) and between mTBF and MVD ( p -value = 0.001, r = 0.378), which was confirmed after applying Bonferroni correction, as the p-value was less than the corrected p -value (0.025). Although there was a borderline positive correlation between the rTBF and tumour grade for the intra-axial tumour group ( p -value = 0.046, r = 0.504), this value was not statistically significant after applying Bonferroni correction, as the p-value was greater than the corrected p -value ( p = 0.016). No statistically significant positive correlation was found between rTBF and extra-axial ( p -value = 0.872, r = 0.045) or posterior fossa and skull base ( p = 0.407, r = 0.420) tumour grade. Conclusion Arterial spin labelling perfusion parameters demonstrate a strong correlation with MVD in brain tumours, regardless of their location. ASL is a promising non-invasive method for the assessment of brain tumour angiogenesis, but it needs further validation with larger homogeneous cohorts. The value of ASL in the pre-operative grading of brain tumours requires further validation.