Introduction
A variety of imaging techniques has been described for the assessment of cerebral perfusion. These techniques have been primarily used to assess cerebral ischaemia [1, 2]; however, the range of perfusion applications is being expanded, including the diagnostic field of cerebral tumours. Perfusion-weighted magnetic resonance imaging (PWI) has been proven to provide additional valuable information about intra-axial brain tumours [3–6]. A correlation among perfusion parameters, tumour grade and treatment response has already been demonstrated through the non-invasive measurement of regional cerebral blood volume (CBV), regional cerebral blood flow (CBF) and permeability (PMB) as a measure of blood-brain barrier disruption by PWI techniques [3–6]. Furthermore, perfusion imaging has shown promising results for distinguishing recurrence from radionecrosis, but also for differentiating cerebral tumour lesions, such as lymphomas and gliomas [3].
Non-invasive assessment of cerebral perfusion by means of dynamic perfusion computed tomography (PCT) has also been used for the evaluation of brain tumours. PCT has exhibited a number of advantages over PWI, the most important of which is the linear relation between density changes and the tissue concentration of the contrast agent. Moreover, PWI, because of susceptibility artefacts generated by haemorrhage or various mineral depositions, can create diagnostic concerns in post-treatment tumour patients. CT is often the first imaging technique that is performed in patients suffering from neurological symptoms caused by brain tumours. Even though non-enhanced CT is not really the imaging technique of choice for a detailed neuroradiological diagnosis of brain tumours, getting additional haemodynamic information from the same device without having to shift technique appears to be attractive [7]. PCT renders important information in patients with intra-axial brain tumours, allowing differentiation not only between low-grade and high-grade gliomas but also between high-grade gliomas and lymphomas, by quantifying regional CBV, CBF and permeability of the blood-brain barrier with a single acquisition [7]. Because tumour neoangiogenesis and neovascularisation play an important role in tumour growth and spread, measurement of perfusion characteristics enables the prediction of tumour grade, the determination of treatment options and the assessment of treatment response and prognosis [8].
The aim of our study was to prospectively evaluate the feasibility and efficacy of PCT in the preoperative differential diagnosis of intra-axial brain tumours. Furthermore, we tried to explore a non-invasive way of quantifying and classifying the characteristics of cerebral gliomas and lymphomas according to their regional perfusion parameters.