American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the preferred study for preoperative staging of patients with newly diagnosed colorectal cancer?

1. Magnetic resonance imaging of the abdomen

2. Contrast-enhanced CT scanning of the chest, abdomen, and pelvis

3. Plain X-ray of the chest

4. Ultrasound of the abdomen

The correct answer is: Contrast-enhanced CT scanning of the chest, abdomen, and pelvis

The preferred study for preoperative staging of patients with newly diagnosed colorectal cancer is contrast-enhanced CT scanning of the chest, abdomen, and pelvis. This imaging modality provides a comprehensive assessment of the disease's extent, allowing for visualization of the primary tumor, lymph node involvement, and any potential metastases to the liver or lungs. A contrast-enhanced CT scan is advantageous because it offers high-resolution images and the ability to evaluate multiple regions simultaneously. It assists in staging the cancer according to the TNM (tumor, node, metastasis) classification, which is crucial for determining prognosis and appropriate management strategies. In cases of colorectal cancer, identifying the presence of distant metastases is vital. The CT scan's ability to detect involvement of lymph nodes and the presence of lesions in the liver and lungs makes it the best choice for preoperative evaluation. Other imaging studies, such as MRI or ultrasound, may have specific applications, but they do not provide the same comprehensive assessment as a contrast-enhanced CT scan in this context.