Preoperative detection of colorectal liver metastases: DWI alone or combined with MDCT is no substitute for Gd-EOB-DTPA-enhanced MRI

Background Magnetic resonance imaging (MRI) with hepatocyte specific contrast has the highest sensitivity for colorectal liver metastases but comes at high costs and long examination times. Purpose To evaluate if preoperative detection of colorectal liver metastases with less resource-consuming diffusion-weighted imaging (DWI) alone or in combination with multidetector computed tomography (MDCT) can compete with gadolinium-etoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI. Material and Methods Forty-four patients with 123 colorectal liver metastases received MDCT and Gd-EOB-DTPA-enhanced MRI including DWI before liver resection for colorectal liver metastases. Five image sets were evaluated by two radiologists. The DWI set consisted of DWI, ADC map, coronal, axial T2-weighted single-shot sequences. The DWI-T2F set contained additionally respiratory-triggered T2-weighted TSE-SPIR sequences. The MDCT set consisted of four-phase MDCT, the MDCT-DWI set also contained DWI. The CE-MRI set contained all MRI sequences including Gd-EOB-DTPA. Reference standards was histopathology and follow-up. Results CE-MRI set had highest sensitivity ( P ≤ 0.013) with 95% compared to 72%, 73%, 73%, and 87% the for DWI set, DWI-T2W-FS set, MDCT set, and MDCT-DWI set, respectively. The CE-MRI set had the highest sensitivity ( P≤0.012) for colorectal liver metastases <10 mm with 87% compared to 55%, 52%, 23%, and 58% for the DWI set, DWI-T2W-FS set, MDCT set, and MDCT-DWI set, respectively. The MDCT-DWI set improved sensitivity overall and in size-dependent subgroup analyses compared to the MDCT set ( P ≤ 0.031). The MDCT-DWI set showed the highest specificity of 98% followed by 98%, 98%, 95%, and 88% for the DWI set, DWI-T2W-FS set, MDCT set, and CE-MRI set, respectively. Conclusion The less resource and time-consuming DWI sets are inferior to Gd-EOB-DTPA-enhanced MRI for the detection of colorectal liver metastases. Gd-EOB-DTPA-enhanced MRI with its excellent sensitivity should be the preferred preoperative modality when meticulous lesion identification is essential. Combination of DWI with MDCT improved significantly sensitivity compared to each modality alone.