Recent advances in the treatment of cerebral gliomas have increased the demands on noninvasive neuroimaging for the diagnosis, therapeutic planning, tumor monitoring, and patient outcome prediction. In the meantime, improved magnetic resonance (MR) imaging techniques have shown much potentials in evaluating the key pathological features of the gliomas, including cellularity, invasiveness, mitotic activity, angiogenesis, and necrosis, hence, further shedding light on glioma grading before treatment. In this paper, an update of advanced MR imaging techniques is reviewed, and their potential roles as biomarkers of tumor grading are discussed.

2Contrast-enhanced T1-weighted imaging (CET1-WI) has been routinely used in cerebral stroke study. [3][4][5] The presence of parenchymal enhancement (PE) on CET1-WI is generally accepted as an indicator of contrast medium leakage across the disrupted BBB. 6 Previous studies have demonstrated an association between the risk of HT after recanalization therapy and the increased BBB permeability shown as PE on CET1-WI during the acute stage.3 However, PE in CET1-WI usually does not appear until several days after the ictus. 2 The phenomenon has been explained by BBB breakdown and luxury reperfusion at the subacute stage. 4 Because the BBB disruption is thought to be present as early as 6 hours after cerebral infarction, it is possible that PE in CET1-WI Background and Purpose-Brain enhancement on contrast-enhanced T1-weighted imaging (CET1-WI) after ischemic stroke is generally accepted as an indicator of the blood-brain barrier disruption. However, this phenomenon usually starts to become visible at the subacute phase. The purpose of this study was to evaluate the time-course profiles of K trans , cerebral blood volume (v p ), and CET1-WI with early detection of blood-brain barrier changes on K trans maps and their role for prediction of subsequent hemorrhagic transformation in acute middle cerebral arterial infarct. Methods-Twenty-six patients with acute middle cerebral arterial stroke and early spontaneous reperfusion, whose MR images were obtained at predetermined stroke stages, were included. T2*-based MR perfusion-weighted images were acquired using the first-pass pharmacokinetic model to derive K trans and v p . Parenchymal enhancement observed on maps of K trans , v p , and CET1-WI at each stage was compared. Association among these measurements and hemorrhagic transformation was analyzed. Results-Ktrans map showed significantly higher parenchymal enhancement in ischemic parenchyma as compared with that of v p map and CET1-WI at early stroke stages (P<0.05). The increased K trans at acute stage was not associated with parenchymal enhancement in CET1-WI at the same stage. Parenchymal enhancement in CET1-WI started to occur at the late subacute stage and tended to be luxury reperfusion-dependent. Patients with hemorrhagic transformation showed higher mean K trans values as compared with patients without hemorrhagic transformation (P=0.02). Conclusions-Postischemic brain enhancement on routine CET1-WI seems to be closely related to the luxury reperfusion at the late subacute stage and is not dependent on microvascular permeability changes at the acute stage. (Stroke. 2013;44:1872-1877.)