Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 21, 2019; 25(35): 5233-5256
Published online Sep 21, 2019. doi: 10.3748/wjg.v25.i35.5233
Colorectal cancer: Parametric evaluation of morphological, functional and molecular tomographic imaging
Pier Paolo Mainenti, Arnaldo Stanzione, Salvatore Guarino, Valeria Romeo, Lorenzo Ugga, Federica Romano, Giovanni Storto, Simone Maurea, Arturo Brunetti
Pier Paolo Mainenti, Institute of Biostructures and Bioimaging of the National Council of Research (CNR), Naples 80145, Italy
Arnaldo Stanzione, Salvatore Guarino, Valeria Romeo, Lorenzo Ugga, Federica Romano, Simone Maurea, Arturo Brunetti, University of Naples "Federico II", Department of Advanced Biomedical Sciences, Naples 80131, Italy
Giovanni Storto, IRCCS-CROB, Referral Cancer Center of Basilicata, Rionero in Vulture 85028, Italy
Author contributions: All authors equally contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Conflict-of-interest statement: No potential conflicts of interest. No financial support.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Pier Paolo Mainenti, MD, Academic Research, Doctor, Institute of Biostructures and Bioimaging of the National Council of Research (CNR), Naples 80145, Italy.
Telephone: +39-347-1873089 Fax: +39-081-5457081
Received: June 18, 2019
Peer-review started: June 20, 2019
First decision: July 22, 2019
Revised: August 6, 2019
Accepted: August 24, 2019
Article in press: August 24, 2019
Published online: September 21, 2019

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

Keywords: Colorectal cancer, Computed tomography, Magnetic resonance imaging, Positron emission tomography, Parametric imaging, Perfusion imaging, Diffusion imaging, Texture analysis

Core tip: While encouraging progress has been made in the management of colorectal cancer (CRC), it still remains among the malignancies with higher incidence and mortality. Tomographic imaging plays a crucial role in the diagnosis, staging and evaluation of treatment responses in CRC; however, it may also conceal critical information that could guide treatment decisions. The quantitative analysis of computed tomography (CT), magnetic resonance imaging and positron emission tomography/CT images could unveil novel promising biomarkers in the form of numerical parameters. These parameters, if validated in terms of their clinical significance, may contribute to redefining the role of diagnostic imaging and improving CRC management.