Comparison of low and high frequency transducers in the detection of liver metastases

Incidentally Detected Liver Metastases during Pancreas Contrast-enhanced Ultrasound

Abstract Purpose: The purpose of current study was to investigate the value of the late-phase enhancement features of pancreas contrast-enhanced ultrasound (CEUS) in the detection of liver metastases in patients with pancreatic ductal adenocarcinomas (PDAC).Methods: From October 2020 to March 2021, 86 patients were prospectively enrolled. The gold standard of liver metastatic and PDAC lesions were based on histopathologically diagnoses and multiple imaging modalities results. B-mode ultrasound (BMUS) was performed to detect suspected liver metastases before CEUS. During the late phase of pancreas CEUS, the entire liver was scanned again to detect hypoenhanced liver metastases. Liver metastases were confirmed by biopsy and histopathological results. The number and size of liver metastases detected by BMUS and during CEUS late phase were recorded and compared.Results: Suspected liver metastases were detected in 14 patients by BMUS (n = 23). During the late phase of CEUS, hypoenhanced liver metastases were detected in 23 patients (n = 87). When compared with BMUS, whole-liver scan during the late phase of CEUS detected more isoechoic, small, or superficially located lesions. Compared with BMUS, the specificity, sensitivity, positive predictive value, and negative predictive value of CEUS in diagnosing of liver metastases in PDAC patients were significantly improved (96.72% vs. 100%, 48% vs. 92%, 85.71% vs. 100%, and 83.10% vs. 96.83%, respectively) (P < 0.05).Conclusion: The late phase whole liver scan during CEUS of pancreas helps to detect more liver metastases, which is important for further clinical decision-making.

Improvement in the routine diagnostic assessment of the liver by high-resolution sonography: an analysis of 999 cases

OBJECTIVE

High-frequency ultrasound transducers have been helpful in certain settings of transabdominal ultrasound examination, and their role in the evaluation of the liver surface in patients with cirrhosis is well documented. However, their value in the routine assessment of the liver has not yet been analysed systematically. The aim of this pilot study was to clarify whether the additional use of high-frequency ultrasound as compared to the standard 3.5 MHz-transducer is of any benefit.

MATERIAL AND METHODS

A total of 999 patients from a tertiary care medical centre were examined with a wideband 3.5 MHz- and a high-frequency transducer (band width 4.5 to 10 MHz) with tissue harmonic imaging using one of two high-end ultrasound machines (Siemens Sonoline Elegra or Hitachi EUB-8500). Findings on hepatic pathologies were collected on a standardized documentation sheet and were evaluated using descriptive statistics.

RESULTS

In all, 948 patients showed a plain liver surface when the 3.5 MHz transducer was used, whereas this was only true for 862 patients examined with the high-frequency probe. Using the 7.5 MHz probe, the structure of the liver parenchyma appeared to be homogeneous (n=800; 80.1%) less often than when the 3.5 MHz probe (n=822; 82.3%) was used. More cases of liver cirrhosis were suspected with the high-frequency probe (n=66; 6.6% as compared with n=49; 4.9%). In 85 patients (8.5%) new hepatic pathologies were described which had not been detected with the 3.5 MHz probe. The examiners judged the high-frequency examination to be helpful in 284 cases. The time needed for the additional examination ranged between 0.5 and 10 min (mean: 2.2 min).

CONCLUSIONS

This study demonstrates that the additional use of a high-frequency transducer during routine abdominal examinations reveals new hepatic pathologies in a significant proportion of examined patients, without substantial prolongation of the overall examination period.