Scientific Abstracts: Liver
Objective: To evaluate the diagnostic performance of 2D and 3D contrast-enhanced ultrasound (CEUS) for detecting residual blood flow in hepatocellular carcinoma (HCC) at 1-2 weeks and 1 month post transarterial chemoembolization (TACE) in a prospective multi-center clinical trial.
Methods: In this IRB approved study, patients provided informed consent to undergo CEUS exams prior to TACE, 1-2 weeks post treatment, and approximately one month post treatment. Patients were enrolled and scanned at three United States academic medical centers. Each exam entailed two bolus contrast injections consisting of 2D CEUS, a 10 minute washout period, and then 3D CEUS. Imaging was performed with a GE Logiq E9 scanner (GE Healthcare) with a C1-6 transducer for 2D imaging and RAB2-5 probe for 3D imaging operating in coded harmonic imaging mode during bolus injection of 0.2-0.3 ml of the ultrasound contrast agent Definity (Lantheus Medical Imaging). Following baseline review, each reader reviewed the 2D and 3D CEUS exams from the 1-2 week and 1 month CEUS exam at least 1 month apart (treating each time point as an independent exam in random order). For each exam, readers were asked to evaluate the presence of residual disease and their overall confidence level (on a 5-point scale). As a reference standard, HCCs were deemed incompletely treated by (in order of preference): pathological examination of explanted livers demonstrating residual viable tumor, tumor enhancement seen with CT or MR and confirmed via angiography during retreatment, tumor growth on 6 month follow-up CE-CT/MRI, or clinical tumor progression.
Results: To date, 99 patients have been enrolled in this study with no adverse events. Contrast-enhancement has been evident in all cases and CEUS volume acquisition rates have ranged from 0.3 to 1.3 volumes/second. Two radiologists have provided reads for the first 60 cases. Of these cases, long-term outcomes demonstrated complete treatment in 25 cases (7 confirmed by explant pathology and 18 by long-term stability on cross sectional imaging) and 35 cases of residual disease (5 confirmed by explant pathology, 19 by retreatment, 7 by long-term cross sectional imaging, and 4 by disease progression). Sensitivity and specificity have ranged from 93-91% and 93-84% respectively with no apparent differences between CEUS at 1-2 weeks and 1 month. When using the 1 month post treatment radiology reads as the clinical standard of care, cross sectional imaging demonstrated a sensitivity of 72% and specificity of 89%. Importantly, the addition of 3D CEUS after 2D CEUS provided no change in diagnostic reads and actually lowered reader confidence.
Conclusions: CEUS is well tolerated in HCC patients treated with TACE and preliminary results indicate this modality has greater sensitivity for detecting residual blood flow indicating viable tumor compared to cross sectional imaging. Additionally, residual disease can be detected by CEUS as early as 1-2 weeks post treatment.