Hindawi, BioMed Research International, (2015), p. 1-2
DOI: 10.1155/2015/397521
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The official history of Computed Tomography perfusion (CTp) began in 1979 when Heinz and his colleagues published their paper [1]. From that date, a limited number of experiences have been carried out to achieve the technique that is now be-coming more familiar thanks to the availability of commercial CTp software platforms that are integrated into today's clinical reporting workstations, allowing a rapid analysis and processing of dynamic data sets. From a technical point of view, CTp requires a rapid intravenous injection of an iodi-nated contrast medium (CM) bolus and sequential imaging to simultaneously monitor changes in the CM concentration as a function of time, both in the tissue of interest and in the vessel that is used as an input function. CTp is thus able to determine, through mathematical models and ded-icated software, the perfusion parameters of a given tissue, such as the blood flow (BF), the blood volume (BV), the mean transit time (MTT), and the capillary permeability surface (PS). In particular, PS is considered a functional CT surrogate marker of neoplastic angiogenesis, focusing on the interest of the use of CTp in oncologic imaging [2]. Today, CTp could routinely offer functional imaging information, as an adjunct to a conventional or morphologic CT examination. In particular, it is a widely applied technique in the evaluation of acute ischemic stroke patients and to investigate other brain diseases, including tumours. It can also be used as an aid to distinguish benign and malignant lesions in body imaging and above all to monitor the treat-ment response in oncologic patients. This has subsequently lead to some authors affirming that CTp is a more sensitive image biomarker than RECIST and tumour density for monitoring early antiangiogenic treatment effects as well as in predicting prognosis and progression-free survival at the end of treatment. However, despite these possibilities, CTp is still considered a niche technique because of some issues. Firstly, the lack of awareness between radiologists, in fact despite the diffusion of commercial CTp software platforms, CTp has not been routinely utilised in clinical practice yet. It also suffers from some limitations due to the high radiation dose delivered to patients, the need for CM injection, and the lack of reproducibility of CTp data obtained from different software packages used and also between the different upgrades of the same commercial software [3]. The dose exposure to the patient is strictly related to the acquisition time required for the dynamic scanning of the volume being analysed. However, a lot of possibilities for reducing the dose exposure to the patient are available today, for example, the axial acquisition opposed to the cine acquisition technique, the combination between CTp and iterative reconstruction techniques, and the possibility to obtain reproducible CTp measurements using a short time acquisition protocol with the CTp deconvolution method. Therefore, if the dose exposure question can be overtaken today, the main problem remains the lack of a standardised