Introduction: Diffusion-weighted MRI (DWI) contributes to N staging of rectal cancers and diagnosis of colorectal liver metastases (CLM). About 15% of CLM patients have loco-regional lymph node (LN) metastases that impact prognosis and treatment strategy. This retrospective study is the first one to evaluate quantitative ADC measurement as a tool to identify metastatic LNs in patients with liver metastases from colorectal cancer.
Methods: All consecutive patients undergoing surgery for CLM between 2008 and 2015 were considered. Inclusion criteria were: intraoperative retrieval of at least one LN; LN ≥ 5 mm; DWI performed ≤2 months before surgery. The ADC and ADCratio (ADCLN/ADCCLM) were computed by two radiologists for all the LNs.
Results: Among 555 patients operated for CLM, 32 met the inclusion criteria. Fifty-six LNs were analyzed and 28 were metastatic. ADC and ADCratio in metastatic LNs were lower than in benign LNs (ADC = 1.37 vs. 1.83 × 10-3 mm2/s, p < 0.001; ADCratio = 1.26 vs. 1.73, p < 0.001). The optimal cut-off value for ADC was 1.48 x 10-3 mm2/s (AUC = 0.85, p < 0.001, sensitivity/specificity/accuracy 79%/93%/86% in per LN-analysis and 94%/86%/91% in per-patient analysis). The optimal cut-off for ADCratio was 1.15 (AUC = 0.80, p < 0.001, sensitivity/specificity/accuracy 69%/93%/81% and 76%,93%/84%). Excellent inter- and intra-operators' agreements were observed.
Conclusion: In patients with CLM, ADC values < 1.48 x 10-3 mm2/s can be postulated as a cut-off to distinguish metastatic LNs.
Keywords: ADC measurement; Colorectal liver metastases; Diffusion-weighted MRI; Lymph node metastases; N staging; Staging of colorectal tumors.
Copyright © 2018. Published by Elsevier Ltd.