Published online Nov 21, 2017. doi: 10.3748/wjg.v23.i43.7765
Peer-review started: August 15, 2017
First decision: August 30, 2017
Revised: September 14, 2017
Accepted: September 19, 2017
Article in press: September 19, 2017
Published online: November 21, 2017
The frequency of focal liver lesion (FLL) detection is increasing because of the development and prevalence of imaging technology, especially ultrasound examinations. The subsequent challenge not only involves efficiently distinguishing between malignant and benign FLLs but also precisely identifying the characteristics of all types of FLLs as different clinical treatments and outcomes may be inherent to each type.
Addressing this challenge involves choosing a diagnostic method that requires minimal time and effort, but can achieve high diagnostic accuracy. Some patients may be ineligible for the currently used imaging techniques, such as CEUS/CT/MRI, because of the risk of triggering or worsening renal failure due to contrast agents, such as iodine used for CT and Gd-DTPA (gadolinium diethylene-trianmine pentaacetic acid) used for MRI. In addition, the agents used in CEUS, CECT, and CEMRI are foreign bodies, and each one could cause hypersensitivity reactions. Additionally, the three techniques are expensive and time-consuming, limiting their widespread application.
Superb microvascular imaging (SMI) is a novel Doppler technique that simulates enhanced ultrasound by using advanced clutter elimination to obtain only vascular flow signals without using any contrast agent. The purpose of our study was to investigate the SMI features of focal liver lesions and to analyze their ability to provide additional information for differential diagnoses.
To explore the ability of SMI to differentially diagnose focal liver lesions and compare SMI morphologies to those of color Doppler ultrasound and enhanced imaging.
Twenty-four patients with 31 focal liver lesions (FLLs) were included in our study, with diagnoses of hemangioma (HE) (n = 17), hepatocellular carcinoma (HCC) (n = 5), metastatic lesions (n = 5), primary hepatic lymphoma (n = 1), focal nodular hyperplasia (FNH) (n = 2), and adenoma (n = 1). Nine lesions were pathologically diagnosed, and 22 lesions were radiologically confirmed, all of which were evaluated by at least two types of enhanced imaging techniques. All patients had undergone SMI. Patients were divided into subgroups based on pathological and radiological diagnoses to analyze SMI manifestations. We also compared the SMI manifestations of the most common malignant FLLs of HCCs and metastatic lesions with those of the most common benign FLLs of HEs.
HEs were classified into three SMI subgroups: diffuse dot-like type (n = 6); strip rim type (n = 8); and nodular rim type (n = 3). The sizes of the three types of HEs were significantly different (P = 0.00, < 0.05). HCCs were classified into two subgroups: diffuse honeycomb type (n = 2) and non-specific type (n = 3). Four of the metastatic lesions were the strip rim type of HE, and the other metastatic lesion was the thick rim type, which is the same as that of lymphoma. FNH was described as a spoke-wheel type, and adenoma as a diffuse honeycomb type. The SMI types of HCCs and metastatic lesions were significantly different from that of HEs (P = 0.048, < 0.05).
SMI technology enables microvascular evaluation of focal liver lesions without using any contrast agent. For HEs, lesion size may affect SMI performance. SMI is able to provide useful information for differentially diagnose HCCs and metastatic lesions from HEs.