Astrocytic tumour grading: a comparative study of three-dimensional pseudocontinuous arterial spin labelling, dynamic susceptibility contrast-enhanced perfusion-weighted imaging, and diffusion-weighted imaging

Abstract

ObjectivesWe hypothesized that three-dimensional pseudocontinuous arterial spin labelling (pCASL) may have similar efficacy in astrocytic tumour grading as dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI), and the grading accuracy may be further improved when combined with apparent diffusion coefficient (ADC) values.MethodsForty-three patients with astrocytic tumours were studied using diffusion weighted imaging (DWI), pCASL, and DSC-PWI. Histograms of ADC and normalized tumour cerebral blood flow values (nCBF on pCASL and nrCBF on DSC-PWI) were measured and analyzed.ResultsThe mean 10 % ADC value was the DWI parameter that provided the best differentiation between low-grade astrocytoma (LGA) and high-grade astrocytoma (HGA). The nCBF and nrCBF (1.810 ± 0.979 and 2.070 ± 1.048) in LGA were significantly lower than those (4.505 ± 2.270 and 5.922 ± 2.630) in HGA. For differentiation between LGA and HGA, the cutoff values of 0.764 × 10-3 mm2/s for mean 10 % ADC, 2.374 for nCBF, and 3.464 for nrCBF provided the optimal accuracy (74.4 %, 86.1 %, and 88.6 %, respectively). Combining the ADC values with nCBF or nrCBF could further improve the grading accuracy to 97.7 % or 95.3 %, respectively.ConclusionspCASL is an alternative to DSC-PWI for astrocytic tumour grading. The combination of DWI and contrast-free pCASL offers a valuable choice in patients with risk factors.Key Points• pCASL shows positive correlation with DSC-PWI in astrocytic tumour grading.• ADC values based on ADC histograms can be an objective method.• Combination of DWI and pCASL or DSC-PWI can improve grading accuracy.

Current Clinical Brain Tumor Imaging

“…57 rCBV has been positively correlated to glioma grade, although some lower grade gliomas such as oligodendrogliomas may have elevated rCBV. 44,58 rCBV has been noted to be increased in infiltrative edema of gliomas compared to acellular vasogenic edema surrounding metastases, a characteristic which may be used to better target biopsy. 59 rCBV may also predict areas of progression in glioma prior to changes on contrast-enhanced MRI as well as survival.…”

Evaluation of recurrent high‐grade gliomas treated with bevacizumab: A preliminary report of 3D pseudocontinuous artery spin labeling

“…Several studies have evaluated the relationship between DCE and DSC perfusion MRI parameters and clinical outcome following antiangiogenic treatment, and demonstrated the perfusion parameters, such as K trans and rCBV, may be predictive of clinical outcome . The 3D FSE pcASL, a noninvasive functional MRI technique to offer absolute values of CBF, has been applied in gliomas and suggested to be valuable for tumor grading . Only a few studies of ASL focused on the correlation of CBF with prognosis, and the results were controversial .…”

“…Due to the histological heterogeneity of rHGGs, the average CBF may more accurately reflect the underlying vascular status than the maximum CBF. According to prior studies, CBF of cerebellum is stable and unaffected by pathology . In addition, some prior studies using DSC values of contralateral NAWM were often used for normalization .…”

“…Third, an ROI (2.6–2.7 cm 2 ) was placed on the NAWM region contralateral to the tumor on the CBF map to measure the average CBF value as aCBF_wm, and normalized metrics of CBF were calculated as: rCBF_wm = aCBF/aCBF_wm; mCBF_wm = mCBF/aCBF_wm. Fourth, two oval ROIs around 3 cm 2 were placed on the center of cerebellum hemisphere as used in prior studies . The average CBF values of both ROIs were extracted and the related mean value was calculated and recorded as aCBF_cb.…”

“…9 Dynamic susceptibility contrast (DSC) PWI, which can assess tumor vasculature and offer a semiquantitative map of relative cerebral blood volume (rCBV), has been widely used in brain tumor grading. [10][11][12][13] Recently, it was proven to be predictive of treatment response in rHGGs. 6,9,14 Nevertheless, DSC involves invasive injection of contrast agents.…”