Intra-operative High-Intensity Focused Ultrasound in Patients With Colorectal Liver Metastases: A Prospective Ablate-and-Resect Study

OBJECTIVE

High-intensity focused ultrasound (HIFU) is a recent, non-ionizing and non-invasive technology of focal destruction. Independence from the heat-sink effect of blood flow makes HIFU an interesting technique for focal ablation of liver tumors. Current available technology is based on extracorporeal treatment that limits use of HIFU for the treatment of liver tumors, as elementary ablations are small and must be juxtaposed to treat tumors, resulting in long-duration treatment. We developed an HIFU probe with toroidal technology, which increases the volume of ablation, for intra-operative use, and we assessed the feasibility and efficacy of this device in patients with colorectal liver metastasis (CLM) measuring less than 30 mm.

METHODS

This study was an ablate-and-resect, prospective, single-center, phase II study. All ablations were performed in the area of liver scheduled for liver resection to avoid loss of chance of recovery. The primary objective was to ablate CLM with safety margins (>5 mm).

RESULTS

Between May 2014 and July 2020, 15 patients were enrolled and 24 CLM were targeted. The HIFU ablation time was 370 s. In total, 23 of 24 CLM were successfully treated (95.8%). No damage occurred to extrahepatic tissues. HIFU ablations were oblate shaped with an average long axis of 44.3 ± 6.1 mm and an average shortest axis of 35.9 ± 6.7 mm. On pathological examination, the average diameter of the treated metastasis was 12.2 ± 4.8 mm.

CONCLUSION

Intra-operative HIFU can safely and accurately produce large ablations in 6 min with real-time guidance (ClinicalTrials.gov identifier: NCT01489787).

Non-invasive high-intensity focused ultrasound treatment of the placenta: a preliminary in-vivo study using a simian model

OBJECTIVE

To demonstrate the feasibility and efficacy of high-intensity focused ultrasound (HIFU) for the non-invasive creation of placental lesions in a simian model.

METHODS

Eight pregnant monkeys were exposed to HIFU treatment after anesthesia, using a toroidal HIFU 2.5-MHz transducer with an integrated ultrasound imaging probe. Lesions on the placental tissue were created non-invasively by placing the HIFU probe on the skin surface. Fetal and maternal parameters, such as maternal heart rate, fetal heart rate and subcutaneous and intra-amniotic fluid temperature, were recorded during HIFU exposure. Cesarean section was performed immediately after the procedure to extract the placenta and examine the fetus and the maternal abdominal cavity. Placental HIFU lesions were assessed by ultrasound, gross pathology and histology.

RESULTS

The mean gestational age of the monkeys was 72 ± 4 days. In total, 13 HIFU procedures were performed. The acoustic power and exposure time were increased progressively. This gradual increase in total energy delivered was used to determine a set of parameters to create reproducible lesions in the placenta without complications. Five placental lesions were observed with average diameters of 6.4 ± 0.5 mm and 7.8 ± 0.7 mm and an average depth of 3.8 ± 1.5 mm. Ultrasound examination of the placentae revealed hyperechoic regions that correlated well with macroscopic analysis of the HIFU lesions. Necrosis of placental tissue exposed to HIFU was confirmed with macroscopic and microscopic analysis. There was no significant variation in maternal and fetal parameters during HIFU exposure.

CONCLUSIONS

This study demonstrates the feasibility of HIFU applied non-invasively to the placental unit in an in-vivo pregnant monkey model. The technique is safe in the immediate short term and is potentially translatable to human pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Efficacy of high-intensity focused ultrasound-assisted hepatic resection (HIFU-AR) on blood loss reduction in patients with liver metastases requiring hepatectomy: study protocol for a randomized controlled trial

BACKGROUND

Liver resection is the only potentially curative treatment for colorectal liver metastases (LM). It is considered a safe procedure, but is often associated with blood loss during liver transection. Blood transfusions are frequently needed, but they are associated with increased morbidity and risk of recurrence. Many surgical devices have been developed to decrease blood loss. However, none of them has proven superior to the standard crushing technique. We developed a new, powerful intra-operative high-intensity focused ultrasound (HIFU) transducer which destroys tissue by coagulative necrosis. We aim to evaluate whether HIFU-assisted liver resection (HIFU-AR) results in reduced blood loss.

METHODS

This is a prospective, single-centre, randomized (1:1 ratio), comparative, open-label phase II study. Patients with LM requiring a hepatectomy for ≥ 2 segments will be included. Patients with cirrhosis or sinusoidal obstruction syndrome with portal hypertension will be excluded. The primary endpoint is normalized blood loss in millilitres per square centimetre of liver section plane. Secondary endpoints are: total blood loss, transection time, transection time per square centimetre of liver area, haemostasis time, clip density on the liver section area, rate and duration of the Pringle manœuvre, rate of patients needing a blood transfusion, length of hospital stay, morbidity, patients with positive resection margin, and local recurrence. Assuming a blood loss of 7.6 ± 3.7 mL/cm² among controls, the study will have 85% power to detect a twofold decrease of blood loss in the experimental arm, using a Wilcoxon (Mann-Whitney) rank-sum test with a 0.05 two-sided significance level. Twenty-one randomized patients per arm are required. Considering the risk of contraindications at surgery, up to eight patients may be enrolled in addition to the 42 planned, with an enrolment period of 24 months. Randomization will be stratified by surgeon.

DISCUSSION

We previously demonstrated the safety and efficacy of intra-operative HIFU in patients operated on for LM. We also demonstrated the efficacy of HIFU-AR in a preclinical study. Participants in the HIFU-AR group of this randomized trial can expect to benefit from reduced blood loss and decreased ischemia of liver parenchyma.

TRIAL REGISTRATION

Clinicaltrial.gov, NCT02728167 . Registered on 22 March 2016.

High-intensity focused ultrasound applied to the placenta using a toroidal transducer: a preliminary ex-vivo study

OBJECTIVE

To demonstrate in an ex-vivo model the feasibility of applying high-intensity focused ultrasound (HIFU) using a toroidal transducer for the creation of placental lesions.

METHODS

In this study we used a toroidal transducer, composed of 32 ring-shaped emitters with an ultrasound probe at the center, operating at a frequency of 2.5 MHz. We examined 45 human placentae, following either normal vaginal delivery or medical termination of pregnancy between 17 and 40 gestational weeks. First, the attenuation coefficients of 12 human placentae were measured and integrated into a numerical model for simulating HIFU lesions. Then, using acoustic parameters from this preliminary study, we performed ex-vivo experiments with 33 human placentae, each overlain with an animal abdominal wall to simulate the maternal wall. We created single HIFU lesions in 25 of these placentae, and a series of six juxtaposed lesions in eight, studying these both sonographically and macroscopically.

RESULTS

Human placental attenuation coefficients of the 12 human placentae ranged from 0.072 to 0.098 Np/cm/MHz, according to gestational age. The 25 single HIFU lesions created had an average diameter of 7.1 ± 3.2 mm and an average depth of 8.2 ± 3.1 mm. The average diameter of the eight series of six juxtaposed HIFU lesions was 23.0 ± 5.0 mm and the average depth was 11.0 ± 4.7 mm. The average thickness of the abdominal walls was 10.5 ± 1.8 mm. No lesions or damage were observed in intervening tissues.

CONCLUSION

This study demonstrates, using an ex-vivo model, the feasibility, reproducibility, harmlessness and effectiveness of HIFU applied to the human placenta.

First clinical experience of intra-operative high intensity focused ultrasound in patients with colorectal liver metastases: a phase I-IIa study

BACKGROUND

Surgery is the only curative treatment in patients with colorectal liver metastases (CLM), but only 10-20% of patients are eligible. High Intensity Focused Ultrasound (HIFU) technology is of proven value in several indications, notably prostate cancer. Its intra-operative use in patients with CLM has not previously been studied. Preclinical work suggested the safety and feasibility of a new HIFU device capable of ablating volumes of up to 2cm x 2cm in a few seconds.

METHODS

We conducted a prospective, single-centre phase I-IIa trial. HIFU was delivered immediately before scheduled hepatectomy. To demonstrate the safety and efficacy of rapidly ablating liver parenchyma, ablations were performed on healthy tissue within the areas scheduled for resection.

RESULTS

In total, 30 ablations were carried out in 15 patients. These ablations were all generated within 40 seconds and on average measured 27.5mm x 21.0mm. The phase I study (n = 6) showed that use of the HIFU device was feasible and safe and did not damage neighbouring tissue. The phase IIa study (n = 9) showed both that the area of ablation could be precisely targeted on a previously implanted metallic mark (used to represent a major anatomical structure) and that ablations could be undertaken deliberately to avoid such a mark. Ablations were achieved with a precision of 1-2 mm.

CONCLUSION

HIFU was feasible, safe and effective in ablating areas of liver scheduled for resection. The next stage is a phase IIb study which will attempt ablation of small metastases with a 5 mm margin, again prior to planned resection.

TRIAL REGISTRATION

ClinicalTrials.govNCT01489787.

First clinical experience of intra-operative high intensity focused ultrasound in patients with colorectal liver metastases: a phase I-IIa study

Background

Surgery is the only curative treatment in patients with colorectal liver metastases (CLM), but only 10–20% of patients are eligible. High Intensity Focused Ultrasound (HIFU) technology is of proven value in several indications, notably prostate cancer. Its intra-operative use in patients with CLM has not previously been studied. Preclinical work suggested the safety and feasibility of a new HIFU device capable of ablating volumes of up to 2cm x 2cm in a few seconds.

Methods

We conducted a prospective, single-centre phase I-IIa trial. HIFU was delivered immediately before scheduled hepatectomy. To demonstrate the safety and efficacy of rapidly ablating liver parenchyma, ablations were performed on healthy tissue within the areas scheduled for resection.

Results

In total, 30 ablations were carried out in 15 patients. These ablations were all generated within 40 seconds and on average measured 27.5mm x 21.0mm. The phase I study (n = 6) showed that use of the HIFU device was feasible and safe and did not damage neighbouring tissue. The phase IIa study (n = 9) showed both that the area of ablation could be precisely targeted on a previously implanted metallic mark (used to represent a major anatomical structure) and that ablations could be undertaken deliberately to avoid such a mark. Ablations were achieved with a precision of 1–2 mm.

Conclusion

HIFU was feasible, safe and effective in ablating areas of liver scheduled for resection. The next stage is a phase IIb study which will attempt ablation of small metastases with a 5 mm margin, again prior to planned resection.

Trial Registration

ClinicalTrials.govNCT01489787