MR Imaging in Real Time Guiding of Therapies in Prostate Cancer

Epidemiology, diagnosis and treatment of anterior prostate cancer

Anterior prostate cancers (APCs) are a group of impalpable neoplasms located in regions anterior to the urethra, which comprise the transition zone, apical peripheral zone and anterior fibromuscular stroma. These regions are typically undersampled using conventional biopsy schemes, leading to a low detection rate for APC and a high rate of false negatives. Radical prostatectomy series suggest prevalence rates of at least 10-30%, but transperineal systematic biopsy is ideal for diagnosis, particularly where multiparametric MRI is unavailable. Combined MRI-targeted and systematic biopsies demonstrate high concordance with final histopathology and lead to the fewest incidences of upgrading and upstaging at radical prostatectomy. Thus, the use of combined biopsy techniques has important implications for preoperative work-up and surgical planning, as APCs are associated with larger cancer volumes and a higher rate of positive surgical margins than posterior prostate cancer. Nevertheless, anterior tumour location might confer a relative resistance to stage progression, as APCs exhibit lower rates of extraprostatic extension, seminal vesical invasion and lymph node metastases than the more commonly seen posterior neoplasms. Few studies have examined the long-term outcomes of partial gland approaches to APCs, but MRI-targeted techniques have the potential to provide real-time intraoperative guidance and maximize the oncological safety of anterior focal treatment options in patients with APC.

Automatic volumetric temperature regulation during in vivo MRI-guided laser-induced thermotherapy (MRg-LITT) with multiple laser probes

BACKGROUND

Clinical Laser-Induced Thermotherapy (LITT) currently lacks precise control of tissue temperature increase during the procedure. This study presents a new method to automatically regulate the maximum temperature increase in vivo at different positions by adjusting LITT power delivered by multiple laser probes using real-time volumetric MR-thermometry.

METHODS

The regulation algorithm was evaluated in vivo on a pig leg muscle. Temperature regulation was performed in volumes surrounding each laser probe tip. The power delivered to each laser probe was automatically adjusted every second using a feedback control algorithm by processing on-the-fly MR-thermometry images (10 slices/second) on a 1.5 T clinical scanner (1.56 mm × 1.56 mm x 3 mm resolution), using the proton-resonance frequency (PRF) shift technique. Several experimental conditions were tested with predefined temperature-time profiles corresponding to conditions of thermal ablation (+30 °C above body temperature) or moderate hyperthermia (+10 and + 15 °C). Control images were acquired after injection of Gadolinium at the end of experiment and were compared with the thermal dose images calculated from the thermometry images.

RESULTS

The mean difference and root mean squared error between target temperatures and measured ones remained below 0.5 °C and 2 °C respectively, for 5 min duration. Lesion sizes observed on thermal dose and on images acquired after gadolinium injection were in good agreement.

CONCLUSION

Automatic regulation of in vivo temperature increase during LITT procedures with multiple laser emitters control is feasible. The method provides an adaptative solution to improve the safety and efficacity of such clinical procedures.

The Thermal Ablation with MRgFUS: From Physics to Oncological Applications

The growing interest in minimal and non-invasive therapies, especially in the field of cancer treatment, highlights a significant shift toward safer and more effective options. Ablative therapies are well-established tools in cancer treatment, with known effects including locoregional control, while their role as modulators of the systemic immune response against cancer is emerging. The HIFU developed with magnetic resonance imaging (MRI) guidance enables treatment precision, improves real-time procedural control, and ensures accurate outcome assessment. Magnetic Resonance-guided Focused Ultrasound (MRgFUS) induces deep coagulation necrosis within an elliptical focal area, effectively encompassing the entire tumor site and allowing for highly targeted radical ablation. The applications of MRgFUS in oncology are rapidly expanding, offering pain relief and curative treatment options for bone metastatic lesions. Additionally, the MRgFUS plays an effective role in targeted optional therapies for early prostate and breast cancers. Emerging research also focuses on the potential uses in treating abdominal cancers and harnessing capabilities to stimulate immune responses against tumors or to facilitate the delivery of anticancer drugs. This evolving landscape presents exciting opportunities for improving patient outcomes and advancing cancer treatment methodologies. In neuro-oncology, MRgFUS utilizes low-intensity focused ultrasound (LIFU) along with intravenous microbubbles to open the blood-brain barrier (BBB) and enhance the intra-tumoral delivery of chemotherapy drugs.

Percutaneous Magnetic Resonance Imaging-Guided Focal Laser Ablation (MRI-FLA) of Prostate Tumors: A Systematic Review and Network Meta-Analysis

Background/Objectives: MRI-guided focal laser ablation (MRI-FLA) is an emerging minimally invasive technique for treating localized prostate tumors, aiming to provide effective cancer control while minimizing side effects. This meta-analysis systematically evaluates the clinical outcomes, technical efficacy, and complication rates associated with MRI-FLA to better understand its therapeutic potential and safety profile in prostate cancer management. Methods: In July 2024, PubMed (MEDLINE) was searched for eligible trials using the PRISMA guidelines. The primary outcome was residual disease (RD). The secondary outcomes were technical efficacy, progression to metastatic disease, cancer-specific mortality, complications, and decreases in the prostate-specific antigen (PSA) level. Results: Nine clinical trials involving 296 patients with prostate tumors treated via MRI-FLA were analyzed. A random effects model showed that the overall RD prevalence after ablation was 20.37% (12.56-29.28%; p = 0.03) and the cancer-free survival rate was 75.62% (64.88-85.10%). The rate of major and minor adverse effects was 14.26% (0.61-37.3%, p < 0.01). Conclusions: MRI-FLA is safe, feasible, and effective, although further trials are required.

The State-of-the-Art and Perspectives of Laser Ablation for Tumor Treatment

Tumors significantly impact individuals' physical well-being and quality of life. With the ongoing advancements in optical technology, information technology, robotic technology, etc., laser technology is being increasingly utilized in the field of tumor treatment, and laser ablation (LA) of tumors remains a prominent area of research interest. This paper presents an overview of the recent progress in tumor LA therapy, with a focus on the mechanisms and biological effects of LA, commonly used ablation lasers, image-guided LA, and robotic-assisted LA. Further insights and future prospects are discussed in relation to these aspects, and the paper proposed potential future directions for the development of tumor LA techniques.

Real-Time and Delayed Imaging of Tissue and Effects of Prostate Tissue Ablation

PURPOSE OF REVIEW

Prostate ablation is increasingly being utilized for the management of localized prostate cancer. There are several energy modalities with varying mechanism of actions which are currently used for prostate ablation. Prostate ablations, whether focal or whole gland, are performed under ultrasound and/or MRI guidance for appropriate treatment plan execution and monitoring. A familiarity with different intraoperative imaging findings and expected tissue response to these ablative modalities is paramount. In this review, we discuss the intraoperative, early, and delayed imaging findings in prostate from the effects of prostate ablation.

RECENT FINDINGS

The monitoring of ablation both during and after the therapy became increasingly important due to the precise targeting of the target tissue. Recent findings suggest that real-time imaging techniques such as MRI or ultrasound can provide anatomical and functional information, allowing for precise ablation of the targeted tissue and increasing the effectiveness and precision of prostate cancer treatment. While intraprocedural imaging findings are variable, the follow-up imaging demonstrates similar findings across various energy modalities. MRI and ultrasound are two of the frequently used imaging techniques for intraoperative monitoring and temperature mapping of important surrounding structures. Follow-up imaging can provide valuable information about ablated tissue, including the success of the ablation, presence of residual cancer or recurrence after the ablation. It is critical and helpful to understand the imaging findings during the procedure and at different follow-up time periods to evaluate the procedure and its outcome.

Suitable T stage for cryosurgery to spare the anus in patients with low rectal cancer

Sphincter preserving therapy is a key research focus for treating low rectal cancer; however, the role of cryotherapy in this process has seldom been reported in the literature. Therefore, we conducted a comprehensive report on the role of cryoablation in sphincter preservation and explored its effect in rectal cancers. An observational study used longitudinal observation and follow-up. Participants were screened from patients whose medical records showed cryotherapy intervention for low rectal cancers from January 2016 to December 2020, with more than 2 years of follow-up. The primary endpoint was progress-free survival, and the secondary outcomes were mainly related to sphincter preservation rate and complications. Thirty-five patients were enrolled in this study, all of whom had their sphincters preserved. Until June 2022, 35 cases achieved long-term progression-free survival (41.77 ± 15.58), with no recurrence observed in 88.57% (31/35) of all patients at follow-up. Cryotherapy showed no significant differences in progress-free survival between sexes (p > 0.05). Cox regression was used to analyze the factors affecting local recurrence, with sex, T stage, size, and cryo-time taken as covariates. The results showed that T stage was a risk factor for local recurrence (p = 0.01, odds ratio: 16.27, 95% confidence interval: 8.20,145.75). Analysis of the T stage according to different subgroups showed that T3 stage was an independent risk factor (p = 0.002). We observed seven cases of complications, which were classified into grades I-II. In patients with low rectal cancers, cryotherapy can safely and effectively preserve the anus and avoid low anterior resection syndrome. Cryoablation has a better curative effect on radical treatment, especially for tumors in the T₀-₂ N₀M₀ stage.