Histotripsy: New technology making waves in IO Mina S Makary & Warren A Campbell IV

Comment & Analysis

Mina S Makary, assistant professor at the Division of Vascular and Interventional Radiology/Department of Radiology at the Ohio State University Wexner Medical Center (Columbus, USA) and collaborator Warren A Campbell IV from Ohio State University’s medical scientist training programme share their take on the impact histotripsy stands to make on the ablation space within interventional oncology (IO).

Ablation techniques utilise thermal stress to induce cell death, which is accomplished using currents, cryotherapy, microwaves, lasers, or ultrasound. While effective, these ablation techniques have limitations. Transducer placement requires percutaneous or laparoscopic access. Reliance on temperature can prevent effective targeting near sensitive structures, and uniform necrosis often cannot be achieved because of the heat-sink effect near vascular structures.

The advent of histotripsy as an ablative modality has the potential to cause a shift in ablation therapies by addressing existing limitations. Histotripsy creates targeted cavitations with large amplitude pulses to mechanically disintegrate tissue—cavitations are transient steamfilled microbubbles that form when high amplitude waves travel through fluid. Rapid expansion and implosion during cavitation causes significant sheer stress to break cells into subcellular components.

Histotripsy has technical advantages over traditional ablation methods. First, renal, hepatic, and intracranial masses can be targeted transdermally. Second, the primary mechanism is mechanical tissue destruction, which improves accuracy and focus on smaller targets. Third, connective tissue is more resistant to histotripsy, reducing the likelihood of collateral damage to blood vessels or biliary structures. Lastly, the area of destruction creates hypoechogenicity which is efficient to monitor in real time. With the principles of histotripsy, there exists the potential to target any tissue in the body for ablation in a precise, rapid approach, sparing non-targeted tissue and without percutaneous incisions or forms of dangerous ionising radiation.

Histotripsy is showing promise in the treatment of cancer. Preclinical animal studies demonstrated histotripsy’s ability to treat liver, prostate, breast, kidney, oesophageal, pancreas, and brain tumours through necrosis. For metastatic tumours, data have also detected an abscopal effect, where untargeted tumours decrease in growth rate. Targeted ablation disrupts the tumour’s evasion of the immune system. Mechanical perturbation of the tumour’s microenvironment increases the exposure of immunological epitopes and removes anti-inflammatory regulatory cells, permitting immune cell infiltration and improved anti-tumour immunity. Recent developments include the phase 1 clinical trial of histotripsy on nonresectable hepatic tumours (THERESA), which was successful—all eight patients experienced no procedural complications two months after the procedure, and tissue was effectively targeted and destroyed in both primary and secondary tumours.

How to avoid (and survive) an audit

Kathy Krol is an interventional radiologist and consultant in interventional radiology practice management based in Boulder, USA. She volunteers for the Society of Interventional Radiology (SIR) Foundation and the American Medical Association.

ACCORDING TO THE AMERICAN ACADEMY of Professional Coders (AAPC), “medical auditing is a systematic assessment of performance within a healthcare organisation. Almost any element of healthcare can be audited, but most audits look at components of payer reimbursement processes to evaluate compliance with payer guidelines and federal and state regulations.”

Many of us will never be audited, but any of us could be audited. Audits may be devastating if they find significant issues. There are ways to decrease the odds of an audit of your practice. In addition, proactively protecting your practice should help you survive an audit should one occur.

Audits are mandated by law in the USA for both Medicare/Medicaid and for private carriers. Medicare estimates it paid US$27.4 billion in improper payments in 2021 alone, and estimates that 6.27% of all payments are improper. Private carriers estimate up to US$68 billion in annual losses due to improper payments. Some law firms suggest that 80% of submitted medical bills have errors. While only a small number of those represent fraud or abuse, it does show how tricky medical billing can be.

There are numerous state and federal laws that address Medicare fraud and abuse. These laws not only define what constitutes a civil or criminal offence, but they also define the penalties for said offences.

Depending on the offence, practices may have to:

● Pay back money that the carrier finds was incorrectly paid

● Pay back money that the carrier finds was incorrectly paid, plus a penalty for every case (US$11,000 fine plus three times the government loss on each case)

● Develop and execute a corrective plan

● Be excluded from participating in the Medicare/ Medicaid programmes

● Do prison time

The penalties depend on the severity, extent, and intent of the infraction. Not knowing that one is making a mistake is not an adequate defence. Wilful intent can be determined by the law even if one does not know that what they are doing is illegal or wrong, as the law can determine that one should have known that they were making a mistake, even if they chose not to be educated on what is correct.

The future of histotripsy is currently being developed in the lab, with a focus on improving the safety, efficacy, and versatility of the procedure.

Utilisation of microbubbles and fluidfilled polymer capsules can make histotripsy safer by reducing the energy required for cavitation. Liposomes could also transport drug payloads (i.e. chemotherapies), where histotripsy initiates targeted release. Histotripsy may also permit the diffusion of larger nonpermeable biopharmaceuticals like heparin and insulin through skin via histotripsy of the stratum corneum, eliminating the need for regular injections. The debulking and tumour-targeting functions have already been proven in clinical trials, but these advancements will increase its synergistic effects with other oncological therapies.

Histotripsy is the most recent development of high-intensity focused ultrasound techniques, which have the added benefit of mechanical tissue destruction with increased precision and targeting that is less invasive than alternative techniques. Histotripsy may also have the added benefit of increasing tumour immunogenicity in metastatic disease. Preclinical models in multiple cancers have been effective, and the first human trial targeting hepatic tumours was safe and effective. The future of histotripsy includes a range of applications to treat patients increasingly safely and non-invasively.

References: See online version of the article at interventionalnews.com

Disclosures: The authors declared no relevant disclosures

There are several things that trigger audits:

● Coding errors

● Billing errors

● Incomplete or improper documentation

● Practice that is outside the norm for that patient population

● Patient complaints

● Random selection

● Whistleblowing

No one is 100% accurate on billing and coding, but careful management of your practice’s revenue cycle can help you identify coding and billing errors (both random and ongoing) and allow you to correct those. Having a compliance plan in place and adhering to that plan is the best way to protect your practice.

Documentation is critical to avoiding an audit, and can be what saves you if you are audited. Complete documentation of what was done for each patient and why is a simple requirement, but often is not performed, leaving the practice vulnerable. If this is not documented, it is considered not done! Trying to remember a specific patient months or years later is impossible without documentation to remind you what you did and why. The SIR standardised reporting templates are available to help cue you to include the appropriate information that completes the medical story for each patient encounter.

Kathy Krol

Cardiovascular-aortic community to come together at CX 2023

From cutting-edge aortic interventions to consensus on revascularisation strategies in the peripheral arteries, the 2023 edition of the Charing Cross (CX) Symposium comes at a crucial time in the calendar for the cardiac, aortic, vascular, and endovascular communities.

The three-day CX Symposium—taking place 25–27 April—returns to the Hilton London Metropole in central London for its second consecutive year, with attendees also tuning in virtually from across the globe. It is anticipated that the event will welcome more than 2,500 in-person attendees, with over 1,000 remote participants.

CX continues its three-year cycle of raising vascular and endovascular controversies in order to challenge the available evidence and to be able to reach a consensus after discussion with an expert audience. Sessions will explore routes to consensus in all vascular domains, spanning aortic, peripheral, venous, acute stroke and vascular access, punctuated by CX debates, live and edited cases, and workshop demonstrations.

Running over the three days, the comprehensive aortic programme opens with aortic techniques and technologies on day one, followed by a full day focused on the abdominal and juxtarenal aorta, and finishing with debate centring on the thoracic aorta.

The sessions bring together worldleading experts in management and treatment of aortic disease from the cardiovascular, vascular and endovascular worlds, with faculty including Gustavo Oderich (University of Texas Health Science Center at Houston, Houston, USA), Joseph Bavaria (University of Pennsylvania, Philadelphia, USA), Maximilian Pichlmaier (Ludwig Maximilian University Munich, Munich, Germany) and Marco