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Functional imaging and emerging techniques in CT
Published in Anju Sahdev, Sarah J. Vinnicombe, Husband & Reznek's Imaging in Oncology, 2020
Vicky Goh, Christian Kelly-Morland, Davide Prezzi
In oncology, perfusion CT parameters act as an imaging surrogate for tumour angiogenesis (via measurement of the rate of leakage from the neovessels) and for tumour hypoxia (via measurement of regional blood flow). Clinicopathological correlative studies comparing in vivo imaging and ex vivo histopathology can be challenging, but a number of studies have suggested moderate associations between perfusion CT and microvessel density (MVD), and vascular endothelial growth factor (VEGF) expression in cancers including lung (8–10), renal (11), gastrointestinal (12,13), liver (14), and pancreatic (15) cancers. There have also been negative studies, in part reflecting the heterogeneity of analyses and immunohistological biomarkers used. Data relating perfusion CT parameters to perfusion-related hypoxia remain limited. In lung cancer, a study has suggested that blood volume is negatively correlated to an exogenous marker of hypoxia, pimonidazole (16).
Clinical Perspectives of Spectral Photon-Counting CT
Published in Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski, Spectral, Photon Counting Computed Tomography, 2020
Salim Si-Mohamed, Loic Boussel, Philippe Douek
Conventional and Dual-energy CT with dual-source and detector assembly with their superior quality for imaging coronary arteries and functional cardiac imaging capability is increasingly used as a noninvasive imaging investigation. They have been proposed to detect myocardial perfusion defects, including following acute or chronic infarction (38). However, studies using CT data are susceptible to beam-hardening artefacts that may mimic perfusion defect. Furthermore, CT, as MRI, allows a visualization of the perfusion defect but not a real quantification of the perfusion. This quantification can be performed with PET but again with a poor accessibility and a high cost. Finally, the radiation dose in perfusion CT is currently too high for a clinical application of CT perfusion.Similarly, studies in animals and humans indicate that myocardial perfusion studies performed with CT accurately detect myocardial ischemia and infarcts compared with single photon emission computed tomography (SPECT), but includes a rather high-radiation exposure. Furthermore, the detection of myocardial late enhancement has been demonstrated with conventional CT (39). However, because of the poor contrast between normal and abnormal myocardium in late enhancement studies with conventional CT limits its clinical use and its potential in determining precisely the different components of reperfusion myocardial lesions.
Central nervous system
Published in David A Lisle, Imaging for Students, 2012
CT angiography is able to provide visualization of the carotid arteries in the neck as well as the cerebral vessels; sites of arterial thrombosis and occlusion are clearly shown. For perfusion CT, CT scans of the brain are obtained during contrast infusion. Various parameters of cerebral perfusion are mapped, including:Cerebral blood flowMean transit timeCerebral blood volume.
Advanced clinical imaging for the evaluation of stem cell based therapies
Published in Expert Opinion on Biological Therapy, 2021
Michail E. Klontzas, George A. Kakkos, Georgios Z. Papadakis, Kostas Marias, Apostolos H. Karantanas
Another state-of-the-art CT method with applications in regenerative medicine is perfusion CT (CTP). CTP enables dynamic analysis of intravascular contrast attenuation, providing measurements of blood flow, blood volume, and a dynamic assessment of tissue vascularity applicable to a wide variety of clinical scenarios including stroke imaging [65], liver oncology [66] and peripheral arterial disease [67]. Wen et al. employed CTP to evaluate the healing of femoral head avascular necrosis (AVN) following treatment with transgenic BMMSCs. The authors compared stem cell treatment to core decompression for AVN treatment, showing that blood volume in the femoral head was similar to normal when BMMSCs were combined with core decompression, which was not the case when decompression was used as monotherapy [68]. Vascular regeneration has been also studied with CTP following adipose MSC delivery in rat fibrotic livers. The authors demonstrated that MSC delivery in fibrotic livers restored portal vasculature, reducing hepatic arterial perfusion while improving liver function tests [69].
Perfusion CT radiomics as potential prognostic biomarker in head and neck squamous cell carcinoma
Published in Acta Oncologica, 2019
M. Bogowicz, S. Tanadini-Lang, P. Veit-Haibach, M. Pruschy, S. Bender, A. Sharma, M. Hüllner, G. Studer, S. Stieb, H. Hemmatazad, S. Glatz, M. Guckenberger, O. Riesterer
The major limitation of this exploratory study is the lack of a validation cohort. In clinical practice, perfusion CT is not a standard diagnostic procedure in head and neck cancer patients and thus, the collection of large datasets is difficult. Nevertheless, as a next step, this model should be validated and compared to previously published CT- and 18F-FDG PET-based models [16,22,24]. One of the inherent limitations of perfusion CT for routine clinical use is a higher radiation exposure to the patient compared to a standard CT scan. However, new iterative reconstruction algorithms were shown to decrease the dose by a factor of 2 while preserving the image quality [34]. Additionally, our robustness study should be extended in the future with inter-observer contouring variability [35].
Role of perfusion CT in the evaluation of adnexal masses
Published in Journal of Obstetrics and Gynaecology, 2019
Veenu Singla, Nidhi Prabhakar, Niranjan Khandelwal, Gaurav Sharma, Tulika Singh, Neelam Aggarwal, Srinivasan Radhika
Perfusion CT (PCT) enables the radiologist to obtain both morphological and functional information of tumours. Neovascularity, an important characteristic of malignant neoplasms, allows rapid tumour growth and proliferation. Perfusion-based imaging enables us to objectively evaluate the neovascularity within a lesion, thus helping to differentiate benign from malignant lesions. PCT may also predict tumour behaviour and assess response to therapy (Miles et al. 2000).