Colorectal liver metastases: radiopathological correlation

Abstract

With the development of chemotherapy regimens, targeted therapies, and hepatic surgery, the survival of patients with colorectal liver metastases (CRLM) has dramatically improved. Imaging plays a central role for the diagnosis, staging, and treatment allocation in these patients. To interpret CRLM on imaging, radiologists must be familiar with the main imaging features of untreated tumors as well as the modifications induced by systemic therapies, and their meaning in relation to pathological tumor response and tumor biology. CRLM have the same histological features as the primary tumor. Most are "non-otherwise specified" (NOS) adenocarcinomas. The mucinous tumor is the most common of the rare subtypes. In NOS tumors, imaging usually differentiates central areas of necrosis from peripheral proliferating tumors and desmoplastic reaction. Areas of mucin mixed with fibrosis are seen in mucinous subtypes to help differentiate the metastases from other tumors cysts or hemangiomas. After treatment, the viable tumor is gradually replaced by ischemic-like necrosis and fibrosis, and remnants cells are mainly located on the periphery of tumors. Imaging can help predict the degree of tumor response, but changes can be difficult to differentiate from the pretherapeutic appearance. When chemotherapy is interrupted or in case of resistance to treatment, a peripheral infiltrating halo of tumor growth may appear. The purpose of the article is to illustrate the significance of the imaging features of colorectal liver metastases during systemic therapy, using radiopathological correlations.

Liver Metastatic Colorectal Tumor Cells Change Their Phenotype During Consecutive Passages on Chick Embryo Chorioallantoic Membrane: Lessons from the Lab to the Clinic

“…Imaging investigations may be useful to predict the degree of tumor response, but changes can be difficult to differentiate from pretherapeutic appearance. It was noticed that the most common pattern of progression after the initial response to chemotherapy was an increase in tumor size due to growth of peripheral tumor cells (20). The aspect, with higher values of intensity in the peripheral xenografts cells was noticed on slides, on the second day after the first transfer, in our study.…”

Evaluation of Response to Immune Checkpoint Inhibitors Using a Radiomics, Lesion-Level Approach

“…This variable measures the intensity values at the 2.5th percentile on the histogram and indicates that lesions with lower CT attenuation showed hyperprogression in the liver. Hepatic metastasis is frequently accompanied by necrosis, which is caused by tumor hypoxia and mainly occurs in centers with poor blood and oxygen supply [ 41 , 42 ]. In addition, the genomic stability of tumor cells in the tumor center is much lower, with a higher possibility of distant metastasis [ 43 ].…”

Comprehensive Imaging Characterization of Colorectal Liver Metastases

“…Interface features could influence chemotherapy selection, in particular for antiangiogenic agents (17,18), inform surgical approach (19) and improve risk stratification for recurrence and overall survival (20,21). These features are also well covered in another recent review (22).…”

“…The major benefit of imaging is the capacity to perform repeated, in vivo assessment of multisite disease, which is a particular advantage in the metastatic setting. In this article, we have described the basis for more complete morphological characterization of CRLM ( 22 ). A further strength of imaging is the potential to perform multiparametric imaging, including functional imaging techniques.…”