Defining MRI Superiority over CT for Colorectal and Neuroendocrine Liver Metastases

SIMPLE SUMMARY: We compared CT and MRI for staging metastatic colorectal or neuroendocrine liver metastases (CRLMs and NELMs, respectively). Data from 76 patients (42 CRLMs; 34 NELMs) were analyzed, with two blinded radiologists (R1 and R2) independently assessing the images. For CRLMs, CT and MRI showed no significant differences in lesion number or size. However, in NELMs, Eovist(®)-enhanced MRI detected more lesions (p = 0.02) and smaller lesions (p = 0.03) than CT. In conclusion, CT and MRI are equivalent for CRLMs, but for NELMs, MRI outperforms CT, potentially impacting treatment planning and surgery. ABSTRACT: Background: We compared CT and MRI for staging metastatic colorectal or neuroendocrine liver metastases (CRLMs and NELMs, respectively) to assess their impact on tumor burden. Methods: A prospectively maintained database was queried for patients who underwent both imaging modalities within 3 months, with two blinded radiologists (R1 and R2) independently assessing the images for liver lesions. To minimize recall bias, studies were grouped by modality, and were randomized and evaluated separately. Results: Our query yielded 76 patients (42 CRLMs; 34 NELMs) with low interrater variability (intraclass correlation coefficients: CT = 0.941, MRI = 0.975). For CRLMs, there were no significant differences in lesion number or size between CT and MRI. However, in NELMs, Eovist(®)-enhanced MRI detected more lesions (R1: 14.3 vs. 12.1, p = 0.02; R2: 14.4 vs. 12.4, p = 0.01) and smaller lesions (R1: 5.7 vs. 4.4, p = 0.03; R2: 4.8 vs. 2.9, p = 0.02) than CT. Conclusions: CT and MRI are equivalent for CRLMs, but for NELMs, MRI outperforms CT in detecting more and smaller lesions, potentially influencing treatment planning and surgery.