Comparison of Primovist-enhanced MRI, Diffusion Weighted MRI and Multidetector CT of Colorectal Liver Metastases

1. Primovist-enhanced Magnetic resonance imaging (MRI) and Diffusion Weighted MRI (DW-MRI) is superior to Multidetector Computed axial Tomography (MDCT) in the detection of colorectal liver metastases. Fatty changes in the liver after chemotherapy treatment likely reduces the chances of seeing metastatic lesions on CT especially when the lesions are small (<10 mm). When compared with CT, Primovist-enhanced MRI and DW-MRI have the potential to provide higher contrast resolution enabling better detection of colorectal liver metastases following chemotherapy. 2. Primovist-enhanced MRI and DW-MRI are superior to CT in assessing and predicting treatment response of patients with colorectal liver metastases to chemotherapy. Primovist-enhanced MRI by providing superior resolution may provide improved accuracy in metastatic lesion margin detection thereby providing higher accuracy in estimating tumor response based on size criteria. DW-MRI provides information indirectly about tumor composition and therefore is likely to be superior to MD-CT in assessing treatment response.

Two groups of patients will be analyzed. The second group consists of patients with colorectal liver metastases who are to go for chemotherapy prior to surgery for metastases resection. This group will be CT and MRI scanned prior to chemotherapy and after chemotherapy. The first group of patients will consist of those patients who have already received chemotherapy and are likely to have surgery to resect liver metastases. This group will have only one set of scans done 4-6 weeks prior to their operation. The pathology of the resected metastases and CT and MRI images will be analyzed and compared.