Hemodynamic Imaging in Cerebral Diffuse Glioma—Part A: Concept, Differential Diagnosis and Tumor Grading

SIMPLE SUMMARY: Diffuse gliomas, and glioblastomas, in particular, represent a diagnostic and clinical challenge. Standard neuroimaging continues to have many limitations for accurate diagnostic assessment, resection planning and treatment follow-up. The present two-review series comprehensively summarizes recent evidence on hemodynamic imaging applications in the context of diffuse cerebral glioma. Part A provides an overview of the concepts underlying hemodynamic imaging modalities and critically discusses the diffuse glioma differential diagnosis and tumor grading results reported in the literature. ABSTRACT: Diffuse gliomas are the most common primary malignant intracranial neoplasms. Aside from the challenges pertaining to their treatment—glioblastomas, in particular, have a dismal prognosis and are currently incurable—their pre-operative assessment using standard neuroimaging has several drawbacks, including broad differentials diagnosis, imprecise characterization of tumor subtype and definition of its infiltration in the surrounding brain parenchyma for accurate resection planning. As the pathophysiological alterations of tumor tissue are tightly linked to an aberrant vascularization, advanced hemodynamic imaging, in addition to other innovative approaches, has attracted considerable interest as a means to improve diffuse glioma characterization. In the present part A of our two-review series, the fundamental concepts, techniques and parameters of hemodynamic imaging are discussed in conjunction with their potential role in the differential diagnosis and grading of diffuse gliomas. In particular, recent evidence on dynamic susceptibility contrast, dynamic contrast-enhanced and arterial spin labeling magnetic resonance imaging are reviewed together with perfusion-computed tomography. While these techniques have provided encouraging results in terms of their sensitivity and specificity, the limitations deriving from a lack of standardized acquisition and processing have prevented their widespread clinical adoption, with current efforts aimed at overcoming the existing barriers.