Contrast enhanced ultrasound guided biopsies of liver lesions not visualized on standard B-mode ultrasound-preliminary experience

Abstract

Background: To assess the technical success of contrast enhanced ultrasound (CEUS) guided biopsies of liver lesions poorly visualized on B-mode ultrasound.

Methods: Patients were selected during the procedure based on the real-time clinical scenario of unsatisfactory B-mode ultrasound lesion visualization and all patients would have otherwise undergone CT guided liver lesion biopsy. A total of 26 patients underwent CEUS guided biopsy and were included in this retrospective analysis. The review of the patients' files included demographic information, lesion characteristics on imaging, procedural details and pathology outcome. Technical success was defined as concordance between the radiological findings, pathology report and clinical follow-up-demonstrating lack of need for re-biopsy or re-biopsy with identical pathological results. Patients with less than 2 months follow-up were excluded from the study.

Results: CEUS guided liver biopsy was successful in 23 out of 26 patients (88.5%). The average procedure time was 30.7±12.3 minutes and the average lesion size was 2.2±1.7 cm. The majority of lesions (80.8%) were hypoenhancing on the delayed phase of CEUS. The mean number of samples taken from each lesion per procedure was 3.2 (±1.7).

Conclusions: CEUS guidance biopsies of focal liver lesions (FLL) that were difficult to visualize on B-mode ultrasound demonstrated high success rate and may be an evolving image guidance modality in selected patients to avoid CT guided procedures.

Keywords: Contrast-enhanced ultrasonography (CEUS) guided interventions; liver lesions.

Figure 1

Patient #4. A 53-year-old male with metastatic colorectal carcinoma presented with a new hypodense liver lesion in segment 4A on CT, measuring 1.8×1.5 cm (A); CT/US fusion was attempted but did not significantly improve lesion visualization (B,C); the lesion revealed to be mildly hypoechoic on B-mode ultrasound (D); after intravenous Definity contrast administration, the lesion demonstrated lower enhancement on the delayed phase in comparison to the surrounding liver parenchyma, making it clearly visible and facilitated biopsy (E). Pathology demonstrated metastatic adenocarcinoma consistent with colonic primary.

Figure 2

Patient #5. A 69-year-old male with a history of hepatitis C and HCC, presented with two heterogeneous predominantly hypodense new liver lesions in segments 5 and 7 on CT (A,B), which were not visualized on B-mode ultrasound (C); the lesion in segment 5 measured 1.8 cm and the lesion in segment 7 measured 1.6 cm. After contrast administration, the lesions were well demarcated from surrounding enhancing parenchyma and both lesions showed irregular margins without significant contrast enhancement (D). CEUS guided biopsy was performed for the 1.6 cm lesion located in segment 7. Pathology demonstrated malignant cells compatible with poorly differentiated adenocarcinoma. HCC, hepatocellular carcinoma; CEUS, contrast enhanced ultrasound.

Figure 3

Patient #21. A 66-year-old male with history of gastric adenocarcinoma presented with a new hypodense lesion in segment 5 of the liver based on CT (A); on B-mode US the lesion is mildly hypoechoic and almost invisible (B); after contrast injection, the lesion is hypoenhancing with clear delineation of the lesion borders (C). Pathology confirmed metastatic disease from gastric adenocarcinoma.

Figure 4

Patient #24—a 74-year-old male with history of hepatocellular carcinoma and colorectal carcinoma. Patient underwent radiofrequency ablation of a liver lesion in segment 4A previously, and now came back with suspected local recurrence. The ablation area is visible on CT (A) as a hypodense area; FDG-PET/CT (B) demonstrates mild peripheral metabolic activity; on B-mode US the lesion appears as subtle hypoechoic (C) and after contrast injection the area is hypoenhancing with superior delineation of the lesion borders (D). Pathology excluded recurrent disease and this is concordant with the imaging findings of a hypodense FLL on CT with mild peripheral hypermetabolism on FDG-PET/CT. FLL, focal liver lesions.