Which imaging modality is most sensitive for detecting liver metastases?

The imaging modality that is most sensitive for detecting liver metastases is Magnetic Resonance Imaging (MRI) with liver-specific contrast agents.

Here are the steps explaining why:

1. MRI provides a detailed view of the liver, allowing for the detection of smaller lesions that may not be visible with other imaging modalities.

2. Liver-specific contrast agents, such as gadoxetic acid, are taken up by normal liver cells but not by tumor cells. This makes tumors stand out more clearly on the images.

3. MRI with liver-specific contrast agents can detect liver metastases as small as a few millimeters in diameter, making it the most sensitive imaging modality for this purpose.

4. Other imaging modalities like CT scan and ultrasound are also used, but they are not as sensitive as MRI. For example, CT scans can miss small metastases and ultrasound is user-dependent and has a lower sensitivity.

5. Therefore, for the highest sensitivity in detecting liver metastases, MRI with liver-specific contrast agents is the preferred choice.