Procedural sedation and analgesia for respiratory-gated MR-HIFU in the liver: a feasibility study

Hypnosis in High-Intensity Focused Ultrasound for Thyroid Nodule Ablation

BACKGROUND Current medical technologies enable physicians to treat patients outside operating rooms using minimally invasive techniques. Non-operating room anesthesia (NORA) represents a growing field of medicine, with an increasing number of cases performed over the last decade. As a result, anesthesia providers will need to enhance their understanding of the resources, medical and paramedical staff, and environment outside the operating room. Patients undergoing such procedures under light conscious sedation still experience discomfort such as pain and anxiety, thus requiring the use of pain control medication or sedative drugs. At the same time, the use of hypnosis is spreading in medical practice, particularly with minimally invasive procedures. Many studies have investigated the use of hypnosis in cases of minimally invasive procedures, showing an effective reduction of patients' discomfort and consumption of pain control medication, thus improving patient safety. CASE REPORT We describe the case of a woman in her 70s who underwent a thyroid nodule thermal ablation through high-intensity focused ultrasound (HIFU) performed under hypnosis in a NORA setting. The procedure was well endured; the patient experienced comfort and was satisfied with having avoided general anesthesia. Post-HIFU follow-up showed a 30% decrease of thyroid nodule volume. The patient was completely satisfied with the esthetic result. The operator did not encounter any difficulties with the awoken patient or movements during the procedure. CONCLUSIONS Our case confirms the effective role of hypnosis in relaxation and coping with painful procedures and highlights patient satisfaction without the use of sedative drugs in the context of NORA procedures.

Sorafenib blocks the activation of the HIF-2α/VEGFA/EphA2 pathway, and inhibits the rapid growth of residual liver cancer following high-intensity focused ultrasound therapy in vivo

BACKGROUND

Insufficient high-intensity focused ultrasound (HIFU) can promote the rapid progression of the residual tumor through the hypoxia inducible factor-2α +(HIF-2α)/vascular endothelial growth factor A (VEGFA)/ephrin type-A receptor 2 (EphA2) pathway. Although sorafenib has been shown to significantly improve the survival of patients with advanced liver cancer, the use of sorafenib in residual tumor tissues following HIFU has rarely been elucidated. Thus, this study aimed to investigate the potential adjuvant therapeutic effects of sorafenib following HIFU in order to reduce the relapse rate following insufficient HIFU.

METHODS

Xenograft tumors were established using nude mice injected with liver cancer cells. At approximately 4 weeks after the inoculation of the tumor cells (tumors reached 1.3-1.5 cm), all mice were randomly divided into 3 groups as follows: i) The control group (no treatment); ii) the HIFU-alone group, and iii) the combination group (HIFU + sorafenib), with 6 mice per group. The residual tumor volume was determined among the different treatment groups. The protein expression levels of HIF-2α, VEGFA and EphA2 were determined by immunohistochemistry and western blotting, and the mRNA levels were detected by RT-qPCR. The microvessel density (MVD) was calculated by CD31 immunohistochemistry staining.

RESULTS

The results revealed that by comparing the control group, insufficient HIFU promoted HIF-2α, VEGFA and EphA2 expression (P < 0.05). Compared with the HIFU-alone group, the protein and mRNA levels of HIF-2α, VEGFA and EphA2 were markedly decreased in the group that received combined treatment with HIFU and sorafenib (P < 0.05). Similar results were obtained for MVD expression. Synergistic tumor growth inhibitory effects were also observed between the control group and HIFU group (P < 0.05).

CONCLUSIONS

The findings of this study demonstrate that the expression of HIF-2α, VEGFA and EphA2 can be inhibited by sorafenib, and that sorafenib is likely to provide an effective adjunct treatment for patients with HCC following HIFU ablation.

Phase I feasibility study of Magnetic Resonance guided High Intensity Focused Ultrasound-induced hyperthermia, Lyso-Thermosensitive Liposomal Doxorubicin and cyclophosphamide in de novo stage IV breast cancer patients: study protocol of the i-GO study

INTRODUCTION

In breast cancer, local tumour control is thought to be optimised by administering higher local levels of cytotoxic chemotherapy, in particular doxorubicin. However, systemic administration of higher dosages of doxorubicin is hampered by its toxic side effects. In this study, we aim to increase doxorubicin deposition in the primary breast tumour without changing systemic doxorubicin concentration and thus without interfering with systemic efficacy and toxicity. This is to be achieved by combining Lyso-Thermosensitive Liposomal Doxorubicin (LTLD, ThermoDox, Celsion Corporation, Lawrenceville, NJ, USA) with mild local hyperthermia, induced by Magnetic Resonance guided High Intensity Focused Ultrasound (MR-HIFU). When heated above 39.5°C, LTLD releases a high concentration of doxorubicin intravascularly within seconds. In the absence of hyperthermia, LTLD leads to a similar biodistribution and antitumour efficacy compared with conventional doxorubicin.

METHODS AND ANALYSIS

This is a single-arm phase I study in 12 chemotherapy-naïve patients with de novo stage IV HER2-negative breast cancer. Previous endocrine treatment is allowed. Study treatment consists of up to six cycles of LTLD at 21-day intervals, administered during MR-HIFU-induced hyperthermia to the primary tumour. We will aim for 60 min of hyperthermia at 40°C-42°C using a dedicated MR-HIFU breast system (Profound Medical, Mississauga, Canada). Afterwards, intravenous cyclophosphamide will be administered. Primary endpoints are safety, tolerability and feasibility. The secondary endpoint is efficacy, assessed by radiological response.This approach could lead to optimal loco-regional control with less extensive or even no surgery, in de novo stage IV patients and in stage II/III patients allocated to receive neoadjuvant chemotherapy.

ETHICS AND DISSEMINATION

This study has obtained ethical approval by the Medical Research Ethics Committee Utrecht (Protocol NL67422.041.18, METC number 18-702). Informed consent will be obtained from all patients before study participation. Results will be published in an academic peer-reviewed journal.

TRIAL REGISTRATION NUMBERS

NCT03749850, EudraCT 2015-005582-23.

A planning strategy for combined motion-assisted/gated MR guided focused ultrasound treatment of the pancreas

Objective: To develop and evaluate a combined motion-assisted/gated MRHIFU heating strategy designed to accelerate the treatment procedure by reducing the required number of sonications to ablate a target volume in the pancreas. Methods: A planning method for combined motion-assisted/gated MRHIFU using 4D-MRI and motion characterization is introduced. Six healthy volunteers underwent 4D-MRI for target motion characterization on a 3.0-T clinical scanner. Using displacement patterns, simulations were performed for all volunteers for three sonication approaches: gated, combined motion-assisted/gated, and static. The number of sonications needed to ablate the pancreas head was compared. The influence of displacement amplitude and target volume size was investigated. Spherical target volumes (8, 15, 20 and 34 mL) and displacement amplitudes ranging from 5 to 25 mm were evaluated. For this case, the number of sonications required to ablate the whole target was determined. Results: The number of required sonications was lowest for a static target, 62 on average (range 49-78). The gated approach required most sonications, 126 (range 97-159). The combined approach was almost as efficient as the hypothetical static case, with an average of 78 (range 53-123). Simulations showed that with a 5-mm displacement amplitude, the target could be treated by making use of motion-assisted MRHIFU sonications only. In that case, this approach allowed the lowest number of sonication, while for 10 mm and above, the number of required sonications increased. Conclusion: The use of a combined motion-assisted/gated MRHIFU strategy may accelerate tumor ablation in the pancreas when respiratory-induced displacement amplitudes are between 5 and 10 mm.

Breath-hold MR-HIFU hyperthermia: phantom and in vivo feasibility

Background: The use of magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) to deliver mild hyperthermia requires stable temperature mapping for long durations. This study evaluates the effects of respiratory motion on MR thermometry precision in pediatric subjects and determines the in vivo feasibility of circumventing breathing-related motion artifacts by delivering MR thermometry-controlled HIFU mild hyperthermia during repeated forced breath holds.Materials and methods: Clinical and preclinical studies were conducted. Clinical studies were conducted without breath-holds. In phantoms, breathing motion was simulated by moving an aluminum block towards the phantom along a sinusoidal trajectory using an MR-compatible motion platform. In vivo experiments were performed in ventilated pigs. MR thermometry accuracy and stability were evaluated.Results: Clinical data confirmed acceptable MR thermometry accuracy (0.12-0.44 °C) in extremity tumors, but not in the tumors in the chest/spine and pelvis. In phantom studies, MR thermometry accuracy and stability improved to 0.37 ± 0.08 and 0.55 ± 0.18 °C during simulated breath-holds. In vivo MR thermometry accuracy and stability in porcine back muscle improved to 0.64 ± 0.22 and 0.71 ± 0.25 °C during breath-holds. MR-HIFU hyperthermia delivered during intermittent forced breath holds over 10 min duration heated an 18-mm diameter target region above 41 °C for 10.0 ± 1.0 min, without significant overheating. For a 10-min mild hyperthermia treatment, an optimal treatment effect (TIR > 9 min) could be achieved when combining 36-60 s periods of forced apnea with 60-155.5 s free-breathing.Conclusion: MR-HIFU delivery during forced breath holds enables stable control of mild hyperthermia in targets adjacent to moving anatomical structures.

Real-Time Spatiotemporal Control of High-Intensity Focused Ultrasound Thermal Ablation Using Echo Decorrelation Imaging in ex Vivo Bovine Liver

The ability to control high-intensity focused ultrasound (HIFU) thermal ablation using echo decorrelation imaging feedback was evaluated in ex vivo bovine liver. Sonications were automatically ceased when the minimum cumulative echo decorrelation within the region of interest exceeded an ablation control threshold, determined from preliminary experiments as -2.7 (log-scaled decorrelation per millisecond), corresponding to 90% specificity for local ablation prediction. Controlled HIFU thermal ablation experiments were compared with uncontrolled experiments employing two, five or nine sonication cycles. Means and standard errors of the lesion width, area and depth, as well as receiver operating characteristic curves testing ablation prediction performance, were computed for each group. Controlled trials exhibited significantly smaller average lesion area, width and treatment time than five-cycle or nine-cycle uncontrolled trials and also had significantly greater prediction capability than two-cycle uncontrolled trials. These results suggest echo decorrelation imaging is an effective approach to real-time HIFU ablation control.

Simultaneous MR thermometry and acoustic radiation force imaging using interleaved acquisition

PURPOSE

A novel and practical method for simultaneously performing MR acoustic radiation force imaging (ARFI) and proton resonance frequency (PRF)-shift thermometry has been developed and tested. This could be an important tool for evaluating the success of MR-guided focused ultrasound procedures for which MR-thermometry measures temperature and thermal dose and MR-ARFI detects changes in tissue mechanical properties.

METHODS

MR imaging was performed using a gradient recalled echo segmented echo-planar imaging pulse sequence with bipolar motion encoding gradients (MEG). Images with ultrasound pulses (ON) and without ultrasound pulses (OFF) during the MEG were interleaved at the repetition time (TR) level. ARFI displacements were calculated by complex subtraction of ON-OFF images, and PRF temperature maps were calculated by baseline subtraction. Evaluations in tissue-mimicking phantoms and ex vivo porcine brain tissue were performed. Constrained reconstruction improved the temporal resolution of dynamic measurements.

RESULTS

Simultaneous maps of displacement and temperature were acquired in 2D and 3D while keeping tissue heating < 1°C. Accuracy of the temperature maps was comparable to the standard PRF sequence. Using constrained reconstruction and subsampled k-space (R = 4.33), 3D simultaneous temperature and displacement maps can be acquired every 4.7 s.

CONCLUSION

This new sequence acquires simultaneous temperature and displacement maps with minimal tissue heating, and can be applied dynamically for monitoring tissue mechanical properties during ablation procedures. Magn Reson Med 79:1515-1524, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Thermal ablation of a confluent lesion in the porcine kidney with a clinically available MR-HIFU system

The incidence of small renal masses (SRMs) sized  <4 cm has increased over the decades (as co-findings/or due to introduction of cross sectional imaging). Currently, partial nephrectomy (PN) or watchful waiting is advised in these patients. Ultimately, 80-90% of these SRMs require surgical treatment and PN is associated with a 15% complication rate. In this aging population, with possible comorbidities and poor health condition, both PN and watchful waiting are non-ideal treatment options. This resulted in an increased need for early, non-invasive treatment strategies such as MR-guided high intensity focused ultrasound (MR-HIFU). (i) To investigate the feasibility of creating a confluent lesion in the kidney using respiratory-gated MR-HIFU under clinical conditions in a pre-clinical study and (ii) to evaluate the reproducibility of the MR-HIFU ablation strategy. Healthy pigs (n  =  10) under general anesthesia were positioned on a clinical MR-HIFU system with integrated cooling. A honeycomb pattern of seven overlapping ablation cells (4  ×  4  ×  10 mm³, 450 W, <30 s) was ablated successively in the cortex of the porcine kidney. Both MR thermometry and acoustic energy delivery were respiratory gated using a pencil beam navigator on the contralateral kidney. The non-perfused volume (NPV) was visualized after the last sonication by contrast-enhanced (CE) T ₁-weighted MR (T ₁ w) imaging. Cell viability staining was performed to visualize the extent of necrosis.

RESULTS

a median NPV of 0.62 ml was observed on CE-T ₁ w images (IQR 0.58-1.57 ml, range 0.33-2.75 ml). Cell viability staining showed a median damaged volume of 0.59 ml (IQR 0.24-1.35 ml, range 0-4.1 ml). Overlooking of the false rib, shivering of the pig, and too large depth combined with a large heat-sink effect resulted in insufficient heating in 4 cases. The NPV and necrosed volume were confluent in all cases in which an ablated volume could be observed. Our results demonstrated the feasibility of creating a confluent volume of ablated kidney cortical tissue in vivo with MR-HIFU on a clinically available system using respiratory gating and near-field cooling and showed its reproducibility.