Savitzky-Golay filter based contrast-enhanced ultrasound quantification in hepatic tumors: Methodology and its correlation with tumor angiogenesis

Quantification of Hepatocellular Carcinoma Vascular Dynamics With Contrast-Enhanced Ultrasound for LI-RADS Implementation

OBJECTIVE

The aim of this study is to describe a comprehensive contrast-enhanced ultrasound (CEUS) imaging protocol and analysis method to implement CEUS LI-RADS (Liver Imaging Reporting and Data System) in a quantifiable manner. The methods that are validated with a prospective single-center study aim to simplify CEUS LI-RADS evaluation, remove observer bias, and potentially improve the sensitivity of CEUS LI-RADS.

MATERIALS AND METHODS

This prospective single-center study enrolled patients with hepatocellular carcinoma (April 2021-June 2022; N = 31; mean age ± SD, 67 ± 6 years; 24 men/7 women). For each patient, at least 2 CEUS loops spanning over 5 minutes were collected for different lesion scan planes using an articulated arm to hold the transducer. Automatic respiratory gating and motion compensation algorithms removed errors due to breathing motion. The long axis of the lesion was measured in the contrast and fundamental images to capture nodule size. Parametric processing of time-intensity curve analysis on linearized data provided quantifiable information of the wash-in and washout dynamics via rise time ( RT ) and degree of washout ( DW ) parameters extracted from the time-intensity curve, respectively. A Welch t test was performed between lesion and parenchyma RT for each lesion to confirm statistically significant differences. P values for bootstrapped 95% confidence intervals of the relative degree of washout ( rDW ), ratio of DW between the lesion and surrounding parenchyma, were computed to quantify lesion washout. Coefficient of variation (COV) of RT , DW , and rDW was calculated for each patient between injections for both the lesion and surrounding parenchyma to gauge reproducibility of these metrics. Spearman rank correlation tests were performed among size, RT , DW , and rDW values to evaluate statistical dependence between the variables.

RESULTS

The mean ± SD lesion diameter was 23 ± 8 mm. The RT for all lesions, capturing arterial phase hyperenhancement, was shorter than that of surrounding liver parenchyma ( P < 0.05). All lesions also demonstrated significant ( P < 0.05) but variable levels of washout at both 2-minute and 5-minute time points, quantified in rDW . The COV of RT for the lesion and surrounding parenchyma were both 11%, and the COV of DW and rDW at 2 and 5 minutes ranged from 22% to 31%. Statistically significant relationships between lesion and parenchyma RT and between lesion RT and lesion DW at the 2- and 5-minute time points were found ( P < 0.05).

CONCLUSIONS

The imaging protocol and analysis method presented provide robust, quantitative metrics that describe the dynamic vascular patterns of LI-RADS 5 lesions classified as hepatocellular carcinomas. The RT of the bolus transit quantifies the arterial phase hyperenhancement, and the DW and rDW parameters quantify the washout from linearized CEUS intensity data. This unique methodology is able to implement the CEUS-LIRADS scheme in a quantifiable manner for the first time and remove its existing issues of currently being qualitative and suffering from subjective evaluations.

Imaging findings of fibrolamellar hepatocellular carcinomas on ultrasonography: A comparison with conventional hepatocellular carcinomas

BACKGROUND

Fibrolamellar hepatocellular carcinoma (FLHCC) is an unusual variant of hepatocellular carcinoma (HCC). Revealing the imaging features is important to the diagnosis of FLHCC.

OBJECTIVE

The aim of this study was to investigate the imaging characteristics of FLHCCs.

METHODS

This retrospective study included 29 patients with histopathologically proved FLHCC and 96 patients proved HCC. All patients underwent an ultrasound examination pre-operation.

RESULTS

The average maximum diameters of the FLHCC and HCC lesions were 7.4±4.1 cm and 4.1±3.0 cm, respectively. On the ultrasound, 79.3% of the FLHCCs and 12.3% of the HCCs showed the internal hyperechoic area; 48.3% of the FLHCCs and 3.3% of the HCCs displayed a strip-like attenuation. Calcification was noted in 20.7% of the FLHCCs, while none in HCCs. On the contrast-enhanced ultrasound (CEUS), all FLHCC lesions and 87.7% of the HCCs displayed hyperenhancement in the arterial phase. An internal, unenhanced central scar appeared in all FLHCCs, while none in HCCs.

CONCLUSIONS

The ultrasonographic features of FLHCC lesions indicate that they are relatively large masses showing the internal hyperechoic area or strip-like attenuation or calcification on the US and hypervascularity with an unenhanced central scar on the CEUS as compared with conventional HCC lesions.

Advances in diagnostic application of ultrasomics in liver lesions

With the progress of medical technology in recent years, radiomics has been rapidly developed and widely used. Ultrasomics, as a branch of radiomics, is gradually applied to liver cancer, breast cancer, and other fields, and some research results have been acknowledged by clinicians. In the study of liver lesions, ultrasound is a vital diagnostic imaging method, but it also has limitations. For example, its performance is inferior to computed tomography or magnetic resonance imaging with regard to the diagnostic specificity for benignity and malignancy. The introduction and progress of ultrasomics provide new methods and ideas that could improve the ability to identify benignity or malignancy of liver lesions, tumor stage, and prognosis of the disease.