Imaging and Metabolic Diagnostic Methods in the Stage Assessment of Rectal Cancer

Abstract

Rectal cancer (RC) is a prevalent malignancy with significant morbidity and mortality rates. The accurate staging of RC is crucial for optimal treatment planning and patient outcomes. This review aims to summarize the current literature on imaging and metabolic diagnostic methods used in the stage assessment of RC. Various imaging modalities play a pivotal role in the initial evaluation and staging of RC. These include magnetic resonance imaging (MRI), computed tomography (CT), and endorectal ultrasound (ERUS). MRI has emerged as the gold standard for local staging due to its superior soft tissue resolution and ability to assess tumor invasion depth, lymph node involvement, and the presence of extramural vascular invasion. CT imaging provides valuable information about distant metastases and helps determine the feasibility of surgical resection. ERUS aids in assessing tumor depth, perirectal lymph nodes, and sphincter involvement. Understanding the strengths and limitations of each diagnostic modality is essential for accurate staging and treatment decisions in RC. Furthermore, the integration of multiple imaging and metabolic methods, such as PET/CT or PET/MRI, can enhance diagnostic accuracy and provide valuable prognostic information. Thus, a literature review was conducted to investigate and assess the effectiveness and accuracy of diagnostic methods, both imaging and metabolic, in the stage assessment of RC.

Keywords: CT; EUS; MRI; PET/CT; PET/MRI; imaging diagnosis; rectal cancer; stage assessment.

Figure 1

A rectal tumor (arrow) detected using CT in the (A) sagittal, (B) transverse, and (C) coronal planes, respectively.

Figure 2

Virtual Colonoscopy (CTC). The image depicts a polyp in the large intestine (arrow).

Figure 3

PET/MR images on a 3-tesla Biograph mMR Siemens^® scanner using fluorodeoxyglucose labeled with fluorine (18F-FDG). The images show rectal cancer (arrow), respectively: (a) MR in T2-weighted sequence, (b) MR in T1-weighted sequence, and (c) fusion of MR images in T1-weighted sequence and PET.