Value of magnetic resonance imaging (MRI) in evaluating T stage and lymph node metastasis in rectal cancer

The article is expertly consulted by Master, Resident, Specialist I Trinh Le Hong Minh - Radiologist - Radiology Department - Vinmec Central Park International General Hospital.

Magnetic resonance imaging in rectal cancer is an important diagnostic method to help evaluate T stage and regional lymph node metastasis. From there, the doctor can make the most suitable treatment option for the patient.

Rectal cancer is the most common type of gastrointestinal cancer. In many studies, rectal cancer has been described in conjunction with colon cancer and is referred to as colorectal cancer.
Most cases of early rectal cancer have no symptoms and are often discovered incidentally through screening. Over the years, the development of rectal endoscopy, biopsy and new imaging methods such as magnetic resonance imaging, computed tomography have contributed to the effective early diagnosis of rectal cancer. more fruitful.
The 5-year survival rate of rectal cancer patients is about 66%. Magnetic resonance imaging is an important imaging test to assess the stage of rectal cancer, helping doctors make the right treatment options. This method not only plays an important role in diagnosing early-stage disease, but also used to evaluate treatment response and cancer recurrence.

2.1 Magnetic resonance imaging of rectal cancer Normal, the rectal wall is about 3mm thick. If the wall of the rectum is thicker than 5mm, there may be an abnormality. Rectal tumors present as asymmetric thickening of the wall or as a mass occupying the lumen of the rectum causing stricture of the rectum. This image can be easily detected if the patient has dilated colon or the tumor has increased contrast enhancement (when performing an MRI).
2.2 Evaluation of rectal cancer T staging by MRI T-reading results were used according to the UICC (International Union for Cancer Control) TNM staging classification in conjunction with the AJCC (Joint Commission). on cancer in the United States). TNM stands for tumor, node, and metastasis. The TNM classification system describes the initial tumor size (T1 - T4), whether the tumor has spread to the lymph nodes (N0 - N3), and whether it has spread to other parts of the body (M0). - M1).
Regarding the magnetic resonance imaging to assess the T stage of rectal cancer, the diagnostic results are as follows:
T1 and T2: The tumor is confined to the intestinal wall; T3: Tumor grows through the intestinal wall, fatty infiltrates in the perirectal fascia: T3a: Tumor invades less than 1mm beyond the muscle layer, not reaching the mesenteric fascia (MRF); T3b: Tumor invades 1-5mm beyond the muscle layer, less than the mesenteric fascia; T3c: Tumor invades less than 5-15mm beyond the muscle layer, less than the mesenteric fascia; T3d: Tumor invades more than 15 mm beyond the muscle layer, less than the mesenteric fascia; T3 MRF - : Tumor invades mesenteric fascia less than 1mm; T3 MRF +: Tumor invades mesenteric fascia 1mm; T4: T4a: Tumor invades serosa or mesenteric fascia; T4b: Tumor invades or attaches to other organs or organs. 2.3 Evaluation of lymph node metastasis in rectal cancer on MRI According to AJCC, regional lymph nodes include: perirectal lymph nodes, ipsilateral, anterior posterior, inferior mesenteric, mesenteric sigmoid, Gerota, internal iliac, external iliac, superior rectum - middle - bottom. A regional lymph node is suspected of metastasis on magnetic resonance imaging (MRI) if it belongs to one of the following three cases:
The lymph node is less than 5mm in size, with 3 warning features of the risk of malignancy: round shape, irregular border, and no signal. uniformity; The lymph nodes are 5 - 9mm in size, with 2 out of 3 warning signs of malignancy, which are irregular margins, heterogeneous lymph node signal and round shape; Nodules over 9mm in size. According to the TNM classification of UICC 2016 combined with AJCC 2010:
N1: Metastasis in 1 - 3 regional lymph nodes. In which, N1a is metastasis in 1 - 3 regional lymph nodes; N1b is metastasis in 2 - 3 regional lymph nodes; N1c is nuclei-satellite metastasis into oligoserosal, mesenteric, and para-rectal (but not peritoneal) tissues but no lymph node metastasis; N2: Metastasis in 4 regional lymph nodes. In which, N2a is metastasis in 4-6 lymph nodes, N2b is metastasis in 7 or more lymph nodes.

Rectal cancer is a dangerous disease with a high mortality rate. Meanwhile, the methods of disease treatment depend greatly on the assessment of the stage of the disease. And magnetic resonance imaging is a method with many advantages because of its high diagnostic accuracy, non-invasiveness, and few complications. Therefore, MRI has high value in diagnosing T stage and lymph node metastasis in rectal cancer. When indicated to perform this method, the patient should absolutely coordinate with all instructions of the doctor.
Early cancer screening is considered a perfect measure in the timely detection and treatment of all types of cancer. Vinmec International General Hospital currently has a high-tech cancer screening and screening package, including genetic testing, imaging, and biomarkers for early tumor detection. A single gene test can assess the risk of 16 common cancers in both men and women (lung cancer, colorectal cancer, breast cancer, pancreatic cancer, cervical cancer) Bowel cancer, stomach cancer, prostate cancer, ....)
Before taking a job at Vinmec Central Park International General Hospital, the position of Doctor of Imaging Department was from February 2018, Doctor Trinh Le Hong Minh used to work as a resident in the imaging department at hospitals: Cho Ray, University of Medicine and Pharmacy, Oncology, People's Gia Dinh, Trung Vuong... from 2012-2015. Officially worked at Cho Ray Hospital from 2015-2016, City International Hospital from 2016-2018.