MR-Guided High-Intensity Directional Ultrasound Ablation of Prostate Cancer

Focused Ultrasound in Cancer Immunotherapy: A Review of Mechanisms and Applications

Ultrasound is well-perceived for its diagnostic application. Meanwhile, ultrasound, especially focused ultrasound (FUS), has also demonstrated therapeutic capabilities, such as thermal tissue ablation, hyperthermia, and mechanical tissue ablation, making it a viable therapeutic approach for cancer treatment. Cancer immunotherapy is an emerging cancer treatment approach that boosts the immune system to fight cancer, and it has also exhibited enhanced effectiveness in treating previously considered untreatable conditions. Currently, cancer immunotherapy is regarded as one of the four pillars of cancer treatment because it has fewer adverse effects than radiation and chemotherapy. In recent years, the unique capabilities of FUS in ablating tumors, regulating the immune system, and enhancing anti-tumor responses have resulted in a new field of research known as FUS-induced/assisted cancer immunotherapy. In this work, we provide a comprehensive overview of this new research field by introducing the basics of focused ultrasound and cancer immunotherapy and providing the state-of-the-art applications of FUS in cancer immunotherapy: the mechanisms and preclinical and clinical studies. This review aims to offer the scientific community a reliable reference to the exciting field of FUS-induced/assisted cancer immunotherapy, hoping to foster the further development of related technology and expand its medical applications.

High-intensity focused ultrasound strategies for treating prostate cancer

ABSTRACT

Prostate cancer (PCa) is a significant health concern globally, necessitating effective treatment options. Typical treatment methods for early stage, particularly localized PCa, encompass radical procedures, such as radical prostatectomy (RP) and radiotherapy (RT), and nonradical focal therapy (FT). FT is a focused approach mainly used for treating small lesions limited to a specific zone of the prostate. Its objective is to achieve cancer control when minimizing damage to benign tissue. High-intensity focused ultrasound (HIFU) is one of the most used modalities in FT for the management of PCa. The progress in HIFU technology showcases continuous advancements, offering clinicians a variety of strategies to cater to diverse patient requirements. The advancements include the development of transrectal and transurethral HIFU machines that offer enhanced treatment distances, magnetic resonance imaging (MRI) fusion capabilities, real-time monitoring, and precise ablation. These improvements contribute to increased treatment effectiveness and better outcomes for patients. This narrative review aims to summarize the use of HIFU technology and its evolution, offering diverse options to clinicians, and explores the safety, effectiveness, and quality of different HIFU strategies, such as whole-gland ablation, hemigland ablation, and focal ablation. We conclude that nonwhole-gland HIFU offers similar cancer control with better short-term functional outcomes and fewer complications compared to whole-gland ablation. Combining HIFU with transurethral resection of the prostate (TURP) improves urinary function and reduces catheterization time. Focal ablation and hemigland ablation show promise in achieving cancer control when preserving continence and potency.

Sono-activated materials for enhancing focused ultrasound ablation: Design and application in biomedicine

The ablation effect of focused ultrasound (FUS) has played an increasingly important role in the biomedical field over the past decades, and its non-invasive features have great advantages, especially for clinical diseases where surgical treatment is not available or appropriate. Recently, rapid advances in the adjustable morphology, enzyme-mimetic activity, and biostability of sono-activated materials have significantly promoted the medical application of FUS ablation. However, a systematic review of sono-activated materials based on FUS ablation is not yet available. This progress review focuses on the recent design, fundamental principles, and applications of sono-activated materials in the FUS ablation biomedical field. First, the different ablation mechanisms and the key factors affecting ablation are carefully determined. Then, the design of sono-activated materials with high FUS ablation efficiencies is comprehensively discussed. Subsequently, the representative biological applications are summarized in detail. Finally, the primary challenges and future perspectives are also outlined. We believe this timely review will provide key information and insights for further exploration of focused ultrasound ablation and new inspiration for designing future sono-activated materials. STATEMENT OF SIGNIFICANCE: The ablation effect of focused ultrasound (FUS) has played an increasingly important role in the biomedical field over the past decades. However, there are also some challenges of FUS ablation, such as skin burns, tumour recurrence after thermal ablation, and difficulty in controlling cavitation ablation. The rapid advance in adjustable morphology, enzyme-mimetic activity, and biostability of sono-activated materials has significantly promoted the medical application of FUS ablation. However, the systematic review of sono-activated materials based on FUS ablation is not yet available. This progress review focuses on the recent design, fundamental principles, and applications in the FUS ablation biomedical field of sono-activated materials. We believe this timely review will provide key information and insights for further exploration of FUS ablation.

MRI-guided Minimally Invasive Focal Therapies for Prostate Cancer

Two cases involving patients diagnosed with localized prostate cancer and treated with MRI-guided focal therapies are presented. Patient selection procedures, techniques, outcomes, challenges, and future directions of MRI-guided focal therapies, as well as their role in the treatment of low- to intermediate-risk localized prostate cancer, are summarized.

Contemporary Review of Multimodality Imaging of the Prostate Gland

Tissue changes and the enlargement of the prostate, whether benign or malignant, are among the most common groups of diseases that affect men and can have significant impacts on length and quality of life. The prevalence of benign prostatic hyperplasia (BPH) increases significantly with age and affects nearly all men as they grow older. Other than skin cancers, prostate cancer is the most common cancer among men in the United States. Imaging is an essential component in the diagnosis and management of these conditions. Multiple modalities are available for prostate imaging, including several novel imaging modalities that have changed the landscape of prostate imaging in recent years. This review will cover the data relating to commonly used standard-of-care prostate imaging modalities, advances in newer technologies, and newer standards that impact prostate gland imaging.

Magnetic resonance imaging-guided ultrasound ablation for prostate cancer - A contemporary review of performance

Prostate cancer (PCa) is one of the most common malignancies in men, but patient outcomes are varied depending on extent of disease. Radical, whole-gland therapies, such as prostatectomy or radiotherapy, are definitive treatments for PCa, but they are associated with significant morbidity, including erectile dysfunction and urinary incontinence. Focal therapies for PCa, whereby the part of gland harboring disease is selectively treated, spares the normal surrounding structures, and minimizes the morbidity associated with whole gland treatment. The use of magnetic resonance imaging (MRI) guidance provides advantages over ultrasound guidance, such as better localization and targeting of clinically significant PCa (csPCa), as well as MRI thermometry which optimizes tissue ablation temperatures. This review will discuss two MRI-guided high-intensity focused ultrasound (HIFU) techniques - transrectal MR-guided focused ultrasound (MRgFUS) and TULSA (transurethral ultrasound ablation) ablation for localized PCa. Overall, recent major trials for MRgFUS and TULSA have shown promising oncological and functional results in the treatment of low- to intermediate-risk PCa. Recent Phase II MRgFUS trials have shown better oncologic outcomes than the published results for focal ultrasound guided HIFU and may justify the additional costs associated with MRI guidance. While initial studies on TULSA have focused on subtotal gland ablation, recent trials assessing oncological outcomes for focal treatment of angular sectors have shown promise.

MR Imaging in Real Time Guiding of Therapies in Prostate Cancer

Magnetic resonance imaging (MRI)-guided therapy for prostate cancer (PCa) aims to reduce the treatment-associated comorbidity of existing radical treatment, including radical prostatectomy and radiotherapy. Although active surveillance has been used as a conservative method to reduce overtreatment, there is a growing demand for less morbidity and personalized (focal) treatment. The development of multiparametric MRI was of real importance in improving the detection, localization and staging of PCa. Moreover, MRI has been useful for lesion targeting within the prostate, as it is used in the guidance of prostate biopsies, by means of cognitive registration, MRI-ultrasound fusion guidance or direct in-bore MRI-guidance. With regard to PCa therapies, MRI is used for precise probe placement into the lesion and to accurately monitor the treatment in real-time. Moreover, advances in MR-compatible thermal ablation allow for noninvasive real-time temperature mapping during treatment. In this review, we present an overview of the current status of MRI-guided therapies in PCa, focusing on cryoablation, focal laser ablation, high intensity focused ultrasound and transurethral ultrasound ablation. We explain the important role of MRI in the evaluation of the completeness of the ablation and during follow-up. Finally, we will discuss the challenges and future development inherent to these new technologies.