Retrospective analysis of CT-guided percutaneous cryoablation for treatment of painful osteolytic bone metastasis

Optical Sensing of Tissue Freezing Depth by Sapphire Cryo-Applicator and Steady-State Diffuse Reflectance Analysis

This work describes a sapphire cryo-applicator with the ability to sense tissue freezing depth during cryosurgery by illumination of tissue and analyzing diffuse optical signals in a steady-state regime. The applicator was manufactured by the crystal growth technique and has several spatially resolved internal channels for accommodating optical fibers. The method of reconstructing freezing depth proposed in this work requires one illumination and two detection channels. The analysis of the detected intensities yields the estimation of the time evolution of the effective attenuation coefficient, which is compared with the theoretically calculated values obtained for a number of combinations of tissue parameters. The experimental test of the proposed applicator and approach for freezing depth reconstruction was performed using gelatin-based tissue phantom and rat liver tissue in vivo. It revealed the ability to estimate depth up to 8 mm. The in vivo study confirmed the feasibility of the applicator to sense the freezing depth of living tissues despite the possible diversity of their optical parameters. The results justify the potential of the described design of a sapphire instrument for cryosurgery.

Cryoablation for the Palliation of Painful Bone Metastasis: A Systematic Review

BACKGROUND

Cryoablation is a minimally invasive procedure to treat painful bone metastases in patients with cancer. We designed a systematic review to understand the safety and effects of cryoablation on the pain and quality of life (QoL) of cancer patients.

METHOD

We searched PubMed, ISI, Cochrane library, and Scopus databases using the keywords "Cryoablation," "Pain," and "Bone metastasis." Inclusion criteria were: (1) Original studies published until September 8, 2022; (2) studies on patients over 18 years and affected by bone metastasis; (3) bone metastasis treated with stand-alone cryoablation; (4) studies reporting patients' pain before and at least one time-point following cryoablation; and (5) English-language studies.

RESULTS

We screened 696 articles. Fifteen studies on 376 patients were included. Time points for pain assessment ranged from 1 day to 6 months. Spine was the most frequent treated location. All studies reported a significant pain reduction between 1 day and 6 months after the cryoablation procedure. The highest mean difference between pre- and post-procedure scores was 5.8 (VAS scale) after 4 weeks. The overall rate of minor and major complications was 12.74%. Cryoablation improved the QoL of cancer patients and decreased the need for analgesics.

CONCLUSION

Cryoablation is a safe and useful procedure for palliating painful bone metastasis and increasing the QoL of cancer patients. Future studies should adopt a standardized pain reporting scale to allow for meta-analysis.

The New Ice Age of Musculoskeletal Intervention: Role of Percutaneous Cryoablation in Bone and Soft Tissue Tumors

In the rapidly evolving field of interventional oncology, minimally invasive methods, including CT-guided cryoablation, play an increasingly important role in tumor treatment, notably in bone and soft tissue cancers. Cryoablation works using compressed gas-filled probes to freeze tumor cells to temperatures below -20 °C, exploiting the Joule-Thompson effect. This cooling causes cell destruction by forming intracellular ice crystals and disrupting blood flow through endothelial cell damage, leading to local ischemia and devascularization. Coupling this with CT technology enables precise tumor targeting, preserving healthy surrounding tissues and decreasing postoperative complications. This review reports the most important literature on CT-guided cryoablation's application in musculoskeletal oncology, including sarcoma, bone metastases, and bone and soft tissue benign primary tumors, reporting on the success rate, recurrence rate, complications, and technical aspects to maximize success for cryoablation in the musculoskeletal system.

Feasibility test of a sapphire cryoprobe with optical monitoring of tissue freezing

This article describes a sapphire cryoprobe as a promising solution to the significant problem of modern cryosurgery that is the monitoring of tissue freezing. This probe consists of a sapphire rod manufactured by the edge-defined film-fed growth technique from Al₂ O₃ melt and optical fibers accommodated inside the rod and connected to the source and the detector. The probe's design enables detection of spatially resolved diffuse reflected intensities of tissue optical response, which are used for the estimation of tissue freezing depth. The current type of the 12.5-mm diameter sapphire probe cooled down by the liquid nitrogen assumes a superficial cryoablation. The experimental test made by using a gelatin-intralipid tissue phantom shows the feasibility of such concept, revealing the capabilities of monitoring the freezing depth up to 10 mm by the particular instrumentation realization of the probe. This justifies a potential of sapphire-based instruments aided by optical diagnosis in modern cryosurgery.

Interventional Radiology in the Management of Metastases and Bone Tumors

Interventional Radiology (IR) has experienced an exponential growth in recent years. Technological advances of the last decades have made it possible to use new treatments on a larger scale, with good results in terms of safety and effectiveness. In musculoskeletal field, painful bone metastases are the most common target of IR palliative treatments; however, in selected cases of bone metastases, IR may play a curative role, also in combination with other techniques (surgery, radiation and oncology therapies, etc.). Primary malignant bone tumors are extremely rare compared with secondary bone lesions: osteosarcoma, Ewing sarcoma, and chondrosarcoma are the most common; however, the role of interventional radiology in this fiels is marginal. In this review, the main techniques used in interventional radiology were examined, and advantages and limitations illustrated. Techniques of ablation (Radiofrequency, Microwaves, Cryoablation as also magnetic resonance imaging-guided high-intensity focused ultrasound), embolization, and Cementoplasty will be described. The techniques of ablation work by destruction of pathological tissue by thermal energy (by an increase of temperature up to 90 °C with the exception of the Cryoablation that works by freezing the tissue up to -40 °C). Embolization creates an ischemic necrosis by the occlusion of the arterial vessels that feed the tumor. Finally, cementoplasty has the aim of strengthening bone segment weakened by the growth of pathological tissue through the injection of cement. The results of the treatments performed so far were also assessed and presented focused the attention on the management of bone metastasis.

CIRSE Standards of Practice on Thermal Ablation of Bone Tumours

Background

Percutaneous thermal ablation is an effective, minimally invasive means of treating a variety of focal benign and malignant osseous lesions. To determine the role of ablation in individual cases, multidisciplinary team (MDT) discussion is required to assess the suitability and feasibility of a thermal ablative approach, to select the most appropriate technique and to set the goals of treatment i.e. curative or palliative.

Purpose

This document will presume the indication for treatment is clear and approved by the MDT and will define the standards required for the performance of each modality. CIRSE Standards of Practice documents are not intended to impose a standard of clinical patient care, but recommend a reasonable approach to, and best practices for, the performance of thermal ablation of bone tumours.

Methods

The writing group was established by the CIRSE Standards of Practice Committee and consisted of five clinicians with internationally recognised expertise in thermal ablation of bone tumours. The writing group reviewed the existing literature on thermal ablation of bone tumours, performing a pragmatic evidence search using PubMed to search for publications in English and relating to human subjects from 2009 to 2019. Selected studies published in 2020 and 2021 during the course of writing these standards were subsequently included. The final recommendations were formulated through consensus.

Results

Recommendations were produced for the performance of thermal ablation of bone tumours taking into account the biologic behaviour of the tumour and the therapeutic intent of the procedure. Recommendations are provided based on lesion characteristics and thermal modality, for the use of tissue monitoring and protection, and for the appropriately timed application of adjunctive procedures such as osseus consolidation and transarterial embolisation.

Results

Percutaneous thermal ablation has an established role in the successful management of bone lesions, with both curative and palliative intent. This Standards of Practice document provides up-to-date recommendations for the safe performance of thermal ablation of bone tumours.

In situ terahertz monitoring of an ice ball formation during tissue cryosurgery: a feasibility test

SIGNIFICANCE

Uncontrolled cryoablation of tissues is a strong reason limiting the wide application of cryosurgery and cryotherapy due to the certain risks of unpredicted damaging of healthy tissues. The existing guiding techniques are unable to be applied in situ or provide insufficient spatial resolution. Terahertz (THz) pulsed spectroscopy (TPS) based on sensitivity of THz time-domain signal to changes of tissue properties caused by freezing could form the basis of an instrument for observation of the ice ball formation.

AIM

The ability of TPS for in situ monitoring of tissue freezing depth is studied experimentally.

APPROACH

A THz pulsed spectrometer operated in reflection mode and equipped with a cooled sample holder and ex vivo samples of bovine visceral adipose tissue is applied. Signal spectrograms are used to analyze the changes of THz time-domain signals caused by the interface between frozen and unfrozen tissue parts.

RESULTS

Experimental observation of TPS signals reflected from freezing tissue demonstrates the feasibility of TPS to detect ice ball formation up to 657-μm depth.

CONCLUSIONS

TPS could become the promising instrument for in situ control of cryoablation, enabling observation of the freezing front propagation, which could find applications in various fields of oncology, regenerative medicine, and THz biophotonics.