Published online Apr 28, 2019. doi: 10.3748/wjg.v25.i16.1986
Peer-review started: February 6, 2019
First decision: March 5, 2019
Revised: March 14, 2019
Accepted: March 24, 2019
Article in press: March 24, 2019
Published online: April 28, 2019
Regional lymph node metastasis in patients with hepatocellular carcinoma (HCC) is not uncommon, and is often under- or misdiagnosed. Regional lymph node metastasis is associated with a negative prognosis in patients with HCC, and surgical resection of lymph node metastasis is considered feasible and efficacious in improving the survival and prognosis. It is critical to characterize lymph node preoperatively. There is currently no consensus regarding the optimal method for the assessment of regional lymph nodes in patients with HCC.
Dual-energy computed tomography (CT) can provide quantitative information with monochromatic spectral images, material decomposition images, spectrum curves, and effective atomic number images. The role of dual-energy CT parameters in the evaluation of malignant lymph nodes has been reported with excellent results. However, there have been no dual-energy CT studies regarding lymph node assessment in HCC.
The main objective of our study was to evaluate the diagnostic value of dual energy CT parameters [such as iodine concentrations (IC), normalized IC (NIC), and slope of the spectral curve (λHU)] in regional lymph node assessment for HCC patients.
In this retrospective study, a total of 156 lymph nodes (33 patients with 104 non-metastatic and 10 patients with 52 metastatic) from 43 patients were finally included. According to the lymph node status, the lymph nodes were divided into group P (52 metastatic) and group N (104 non-metastatic). According to the active hepatitis diagnosis standard, the lymph nodes in groups P and N were further divided into an active hepatitis group (group P1, n = 34; group N1, n = 73) and a non-active hepatitis group (group P2, n = 18; group N2, n = 31), respectively. All patients underwent three-phase dual-energy CT scan preoperatively [arterial phase (AP), portal phase (PP), and delayed phase (DP)]. The maximal short axis diameter (MSAD), IC, NIC, and λHU of each group in the AP, PP, and DP were analyzed.
The MSAD, IC, NIC, and λHU showed statistical differences between groups P and N (P < 0.05 for all) in dual-energy CT scans in all the three phases. The diagnostic value of IC, NIC, and λHU in the PP to distinguish benign from metastatic lymph nodes was the best among the three phases (AP, PP, and DP), with a sensitivity up to 81.9%, 83.9%, and 81.8%, and specificity up to 82.4%, 84.1% and 84.1%, respectively. To distinguish benign from metastatic lymph nodes, the diagnostic value of combined analyses of MSAD with IC, NIC, or λHU in PP was superior to the dual energy CT parameters alone, with a sensitivity up to 84.5%, 86.9%, and 86.2%, and a specificity up to 83.0%, 93.6% and 89.8%, respectively. Between groups P1 and P2 and groups N1 and N2, only IC, NIC, and λHU between groups N1 and N2 in the PP had a statistically significant difference (P < 0.05).
Dual-energy CT parameters (IC, NIC, and λHU) are sensitive and specific, and can help to differentiate benign from metastatic lymph nodes in patients with HCC, especially in PP CT scans. The diagnostic efficacy of combined analysis of MSAD with IC, NIC, or λHU values is superior to using any single parameter alone. Active hepatitis does not deteriorate the capabilities for characterization of metastatic lymph nodes.
The future direction in this field will probably focus on the comparison of diagnostic efficacy of different imaging methods to differentiate benign from metastatic lymph nodes in patients with HCC, e.g., between dual-energy CT and magnetic resonance imaging.