Rectal cancer refers to cancer that develops in the terminal part of the large intestine. In particular, the rectum is the part of the large intestine that is located immediately above the tube that ends in the anus and is approximately 15 cm long.

Its location differentiates the way it is treated, in relation to cancer of the rest of the colon, and this because it is located in a more difficult to access area, with particularities consisting in the fact that it borders other organs and especially the anal canal, through which it is controlled defecating.

Predisposing factors that contribute to the development of rectal cancer are a diet rich in fat, a sedentary lifestyle, diabetes, obesity, smoking, alcohol, other bowel diseases (polyps, inflammatory diseases, heredity, age >50).

Symptoms

Common symptoms include constipation, diarrhea, alternation of the two, pain, weakness, weight loss, rectal blood.
In the event of the above symptoms, an examination by a gastroenterologist is advisable, which includes, in addition to the history, a clinical examination and a rectoscopy-colonoscopy. If the diagnosis of rectal cancer is confirmed, the next important step is to determine its size, its exact location, whether it is related to neighboring organs, but also whether there are sites of cancer in other organs away from the rectum.

Radiological control

In this phase of the treatment, the radiological control enters. Today, with the current technological development, many possibilities are provided for the diagnosis of rectal cancer with the use of the latest technology of CT and MRI scanners, ultrasound scanners, as well as new methods such as PET-CT.

It is extremely important that the radiologist who is asked to examine patients with rectal cancer has the appropriate training and experience.

Also, the patient who comes to the radiology laboratory with a diagnosis of rectal cancer should provide any relevant information (endoscopy result, medical note of the referring doctor).

As a rule, it is very helpful and the clinician’s pre-examination contact with the radiologist should be sought so that the latter is able to properly plan the required examinations.

Magnetic resonance imaging of the rectum

The main examination for the study of rectal cancer is the magnetic resonance imaging. It is important that the rectal MRI is performed in an advanced technology Magnetic Tomograph (3 Tesla).

Claustrophobic patients should be advised that open MRIs are not suitable for this examination and encouraged to undergo the examination in a 3 Tesla MRI with appropriate preparation.

The patient must fast for 6 hours before the test and no liquids are allowed until 1 hour before the test.

On the day of the examination, the patient should remove all metal objects and anything that may contain metal elements (make-up, jewelry, headphones, removable materials, dentures).

Before the examination, the patient is asked to fill in the relevant consent form and report the possible presence of the pacemaker or any metal material on the body.

The duration of the Magnetic Tomography of the rectum does not exceed 30 minutes during which the patient is in a supine position, and according to the current guidelines, the administration of intravenous contrast medium is not required.

Completion of the radiodiagnostic study of rectal cancer is done by performing a CT scan of the chest and upper abdomen. These examinations do not exceed 15 minutes in duration, however they require the administration of intravenous contrast agent.

Therefore, it is mandatory for the patient to fast at least 6 hours before the examination (fluids are allowed as in the MRI scan) and to receive anti-allergy treatment if there is a history of allergy mainly to iodine.

In special cases, in order to better determine the local extent of rectal cancer as well as the possible presence of locations in other organs, we use intrarectal ultrasound and PET-CT examination respectively.

The role of radiology in the management of patients with rectal cancer is important, since the combination of MRI and CT usually provides all the information required for the correct treatment planning and successful patient management.