What is the preferred initial imaging modality to evaluate suspected colorectal liver metastases?

What is the preferred initial imaging modality to evaluate suspected colorectal liver metastases?

• A. Ultrasound abdomen
• B. MRI liver
• C. Contrast-enhanced CT scan of chest, abdomen, pelvis
• D. PET-CT

Answer: (C)

When colorectal cancer is suspected to have spread to the liver, the best initial imaging is a contrast-enhanced CT scan of the chest, abdomen, and pelvis. This study quickly provides a staged view of the liver for metastases and also screens for extrahepatic disease that would alter management, all in one session. The multiphasic protocol with arterial and portal venous phases helps differentiate lesions and accurately assess their size and number, while the chest component checks for lung metastases, a common site of spread. MRI of the liver offers higher sensitivity for small lesions and is valuable as a problem-solving test when CT is inconclusive or when detailed liver mapping is needed for planning, but it isn’t typically used first. Ultrasound can miss smaller lesions and is less reliable for comprehensive staging, and PET-CT isn’t as sensitive for small liver metastases and is not the preferred initial test.

When colorectal cancer is suspected to have spread to the liver, the best initial imaging is a contrast-enhanced CT scan of the chest, abdomen, and pelvis. This study quickly provides a staged view of the liver for metastases and also screens for extrahepatic disease that would alter management, all in one session. The multiphasic protocol with arterial and portal venous phases helps differentiate lesions and accurately assess their size and number, while the chest component checks for lung metastases, a common site of spread. MRI of the liver offers higher sensitivity for small lesions and is valuable as a problem-solving test when CT is inconclusive or when detailed liver mapping is needed for planning, but it isn’t typically used first. Ultrasound can miss smaller lesions and is less reliable for comprehensive staging, and PET-CT isn’t as sensitive for small liver metastases and is not the preferred initial test.