Prognostication and response assessment in liver and pancreatic tumors: The new imaging

Abstract

Diffusion-weighted imaging (DWI), dynamic contrastenhanced magnetic resonance imaging (DCE-MRI) and perfusion computed tomography (CT) are technical improvements of morphologic imaging that can evaluate functional properties of hepato-bilio-pancreatic tumors during conventional MRI or CT examinations. Nevertheless, the term "functional imaging" is commonly used to describe molecular imaging techniques, as positron emission tomography (PET) CT/MRI, which still represent the most widely used methods for the evaluation of functional properties of solid neoplasms; unlike PET or single photon emission computed tomography, functional imaging techniques applied to conventional MRI/CT examinations do not require the administration of radiolabeled drugs or specific equipments. Moreover, DWI and DCE-MRI can be performed during the same session, thus providing a comprehensive "one-step" morphological and functional evaluation of hepato-bilio-pancreatic tumors. Literature data reveal that functional imaging techniques could be proposed for the evaluation of these tumors before treatment, given that they may improve staging and predict prognosis or clinical outcome. Microscopic changes within neoplastic tissues induced by treatments can be detected and quantified with functional imaging, therefore these techniques could be used also for posttreatment assessment, even at an early stage. or altered cellular membranes will present diffusion restriction, which is depicted as signal hyperintensity areas on high b-value DW images and hypointensity on the apparent diffusion coefficient (ADC) maps; ADC measurement can also quantify water molecules' diffusion. As dedifferentiation or therapies may induce microscopic changes in neoplastic tissues that could modify water molecules' diffusion, DWI can distinguish between different degrees of malignancy and can be also proposed for post-treatment monitoring. Moreover, DWI can be performed in a single session with DCE-MRI, thus providing a comprehensive "one-step" morphological and functional evaluation of hepatobilio-pancreatic tumors.Perfusion imaging techniques evaluate changes in signal intensity (DCE-MRI) or density (pCT) after contrast medium injection, being therefore able to assess microvascularization through the evaluation of the dynamics of contrast medium distribution from vessels to the neoplastic tissue. Perfusion parameters are therefore theoretically good candidates for the evaluation of microscopic vascular differences between lesions with different pathological grade and for the assessment of treatment response, especially after chemoembolization or during treatments with antiangiogenic drugs.This editorial analyzes up-to-date literature data regarding the application of functional imaging techniques, apart from molecular imaging, to hepatic and pancreatic tumors, with particular emphasis on correlations to pathological features, prognostic stratification and therapeutic response assessment. FUNCTIONAL IMAGING TECHNIQUES: TECHNICAL BASESIn 1965 Stejskal and Tanne...

Dynamic Contrast-enhanced MR Imaging of Advanced Hepatocellular Carcinoma: Comparison with the Liver Parenchyma and Correlation with the Survival of Patients Receiving Systemic Therapy

“…Therefore, DCE MR imaging can be used to reliably depict and quantify the suppression of tumor vascular permeability induced by antiangiogenic agents. In many current clinical trials for new antiangiogenic agents, DCE MR imaging was used as an early imaging biomarker to evaluate patients' response to treatment (14)(15)(16).…”

“…On the basis of these findings, we hypothesized that patients with high tumor angiogenesis have elevated perfusion parameters and are more likely to respond to the antiangiogenic effects of systemic therapy (39). Such patients should have a more satisfactory survival outcome than those with low tumor angiogenesis (16). Additional studies are required to validate the DCE MR imaging parameters that can be used to monitor vascular changes after local or systemic therapy (14,16,40).…”

“…Such patients should have a more satisfactory survival outcome than those with low tumor angiogenesis (16). Additional studies are required to validate the DCE MR imaging parameters that can be used to monitor vascular changes after local or systemic therapy (14,16,40).…”

Computed Tomography Imaging Assessment of Postexternal Beam Radiation Changes of the Liver

“…Standardization in image interpretation has not been achieved [5] and the available data suggest that postradiation imaging changes may vary by technique, regimen and dose. Furthermore, the value of complementary imaging techniques, especially MRI and PET, may provide critical additional information to help distinguish benign from pathologic changes [33]. Active research in areas such as diffusion-weighted imaging suggests incorporation of these parameters provides clinically meaningful predictive information [34,35].…”

Pankreas kanseri -karaciğer metastazlarında diffüzyon ağırlıklı manyetik rezonans görüntüleme

“…B değeri difüzyon sekansının sensitivitesini belirleyen teknik bir parametredir (13). Yapılan birçok çalışmada kitlelerin malinite dereceleri arasında ADC değerlerinin anlamlı farklılık gösterdiği belirtilmiştir (14).…”