Differentiation between primary CNS lymphoma and glioblastoma: qualitative and quantitative analysis using arterial spin labeling MR imaging

To evaluate the diagnostic performance of arterial spin labelling perfusion weighted images (ASL-PWIs) to differentiate primary CNS lymphoma (PCNSL) from glioblastoma (GBM). ASL-PWIs of pathologically confirmed PCNSL (n = 21) or GBM (n = 93) were analysed. For qualitative analysis, tumours were visually scored into five categories based on ASL-CBF maps. For quantitative analysis, normalised CBF values were derived by contralateral grey matter (GM) in intra- and peritumoral areas (nCBF(intratumoral) and nCBF(peritumoral), respectively). Visual scoring scales and quantitative parameters from PCNSL and GBM were compared. In addition, the area under the receiver-operating characteristic (ROC) curve was used to determine the diagnostic accuracy of ASL-PWI for differentiating PCNSL from GBM. Weighted kappa or intraclass correlation coefficients (ICCs) were used to assess reliability between two observers. In qualitative analysis, scores 5 (CBFintratumoral > CBFGM, 68.8% [64/93]) and 4 (CBFintratumoral ae CBFGM, 47.6% [10/21]) were the most frequently reported scores for GBM and PCNSL, respectively. In quantitative analysis, both nCBF(intratumoral) and nCBF(peritumoral) in PCNSL were significantly lower than those in the GBM (nCBF(intratumoral), 0.89 +/- 0.59 [mean and SD] vs. 2.68 +/- 1.89, p < 0.001; nCBF(peritumoral), 0.17 +/- 0.08 vs. 0.45 +/- 0.28, p < 0.001). nCBF(peritumoral) demonstrated the best diagnostic performance (area under the ROC curve: visual scoring, 0.814; nCBF(intratumoral), 0.849; nCBF(peritumoral), 0.908; p < 0.001 for all). Interobserver agreements for visual scoring (weighted kappa = 0.869), nCBF(intratumoral_GM) (ICC = 0.958) and nCBF(peritumoral_GM) (ICC = 0.947) were all excellent. ASL-PWI performs well in differentiating PCNSL from GBM in both qualitative and quantitative analyses. ASL-PWI performs well (AUC > 0.8) in differentiating PCNSL from GBM. The visual scoring template demonstrated good diagnostic performance, similar to quantitative analysis. nCBF (peritumoral) demonstrated better diagnostic performance than nCBF (intratumoral) or visual scoring.