Percutaneous radiofrequency ablation: minimally invasive therapy for renal tumors

Triarylboron-Doped Acenethiophenes as Organic Sonosensitizers for Highly Efficient Sonodynamic Therapy with Low Phototoxicity

The development of efficient organic sonosensitizers is crucial for sonodynamic therapy (SDT) in the field of cancer treatment. Herein, a new strategy for the development of efficient organic sonosensitizers based on triarylboron-doped acenethiophene scaffolds is presented. The attachment of boron to the linear acenethiophenes lowers the lowest unoccupied molecular orbital (LUMO) energy, resulting in redshifted absorptions and emissions. After encapsulation with the amphiphilic polymer DSPE-mPEG₂₀₀₀ , it is found that the nanostructured BAnTh-NPs and BTeTh-NPs (nanoparticles of BAnTh and BTeTh) shows efficient hydroxyl radical (^• OH) generation under ultrasound (US) irradiation in aqueous solution with almost no phototoxicity, which can overcome the shortcomings of O₂ -dependent SDT and avoid the potential cutaneous phototoxicity issue. In vitro and in vivo therapeutic results validate that boron-doped acenethiophenes as sonosensitizers enable high SDT efficiency with low phototoxicity and good biocompatibility, indicating that boron-functionalization of acenes is a promising strategy toward organic sonosensitizers for SDT.

Morphological and hemodynamic analysis of the patient-specific renal cell carcinoma models

Although the morbidity of renal cell carcinoma (RCC) has been increasing as the seventh most common tumours, to our knowledge, there is few studies foucsing on the hemodynamics of the renal artery (RA) with RCC. The objective of this study is to perform morphological and hemodynamic analysis of the RA and abdominal aorta artery (AAA) in the control healthy and RCC patient groups. Three-dimensional (3D) geometries are reconstructed from 18 control healthy subjects and 15 RCC patients based on Computed Tomography Angiography (CTA) images. There is higer in the lumen diameter of the RA (6.21 ± 0.89 mm) and curvature of the RA (1.2 ± 0.07) in the RCC patient group compared with the control healthy group (4.29 ± 1.08 mm, 1.1 ± 0.1), respectively. In the hemodynamic analysis, the surface area ratio (%) of low time-averaged wall shear stress (SAR-TAWSS) at the RA (10.65 ± 11.65) and AAA (48.49 ± 12.79) in the RCC patient group is significantly higher than that in the control healthy group (0.23 ± 0.22, 21.57 ± 20.5), respectively. It is found that RCC altered the morphology of the RA in the RCC patient group, which could deteriorate the hemodynamic environment of the RA and AAA. The finding in this study could enhance us to understand the progression of vascular disease caused by RCC.

Design and Challenges of Sonodynamic Therapy System for Cancer Theranostics: From Equipment to Sensitizers

As a novel noninvasive therapeutic modality combining low-intensity ultrasound and sonosensitizers, sonodynamic therapy (SDT) is promising for clinical translation due to its high tissue-penetrating capability to treat deeper lesions intractable by photodynamic therapy (PDT), which suffers from the major limitation of low tissue penetration depth of light. The effectiveness and feasibility of SDT are regarded to rely on not only the development of stable and flexible SDT apparatus, but also the screening of sonosensitizers with good specificity and safety. To give an outlook of the development of SDT equipment, the key technologies are discussed according to five aspects including ultrasonic dose settings, sonosensitizer screening, tumor positioning, temperature monitoring, and reactive oxygen species (ROS) detection. In addition, some state-of-the-art SDT multifunctional equipment integrating diagnosis and treatment for accurate SDT are introduced. Further, an overview of the development of sonosensitizers is provided from small molecular sensitizers to nano/microenhanced sensitizers. Several types of nanomaterial-augmented SDT are in discussion, including porphyrin-based nanomaterials, porphyrin-like nanomaterials, inorganic nanomaterials, and organic-inorganic hybrid nanomaterials with different strategies to improve SDT therapeutic efficacy. There is no doubt that the rapid development and clinical translation of sonodynamic therapy will be promoted by advanced equipment, smart nanomaterial-based sonosensitizer, and multidisciplinary collaboration.

Micro/Nanoparticle-Augmented Sonodynamic Therapy (SDT): Breaking the Depth Shallow of Photoactivation

The fast development of photoactivation for cancer treatment provides an efficient photo-therapeutic strategy for cancer treatment, but traditional photodynamic or photothermal therapy suffers from the critical issue of low in vivo penetration depth of tissues. As a non-invasive therapeutic modality, sonodynamic therapy (SDT) can break the depth barrier of photoactivation because ultrasound has an intrinsically high tissue-penetration performance. Micro/nanoparticles can efficiently augment the SDT efficiency based on nanobiotechnology. The state-of-art of the representative achievements on micro/nanoparticle-enhanced SDT is summarized, and specific functions of micro/nanoparticles for SDT are discussed, from the different viewpoints of ultrasound medicine, material science and nanobiotechnology. Emphasis is put on the relationship of structure/composition-SDT performance of micro/nanoparticle-based sonosensitizers. Three types of micro/nanoparticle-augmented SDT are discussed, including organic and inorganic sonosensitizers and micro/nanoparticle-based but sonosensitizer-free strategies to enhance the SDT outcome. SDT-based synergistic cancer therapy augmented by micro/nanoparticles and their biosafety are also included. Some urgent critical issues and potential developments of micro/nanoparticle-augmented SDT for efficient cancer treatment are addressed. It is highly expected that micro/nanoparticle-augmented SDT will be quickly developed as a new and efficient therapeutic modality which will find practical applications in cancer treatment. At the same time, fundamental disciplines regarding materials science, chemistry, medicine and nanotechnology will be advanced.

Real-time magnetic resonance imaging-guided cryoablation of small renal tumors at 1.5 T

OBJECTIVES

Real-time magnetic resonance imaging (MRI)-guided cryoablation has been investigated in open MRI systems with low magnetic fields (0.2-0.5 T). More advanced imaging techniques and faster imaging rates are possible at higher magnetic fields, which often require a closed-bore magnet design. However, there is very little experience with real-time interventions in closed-bore 1.5-T MRI units. Herein, we report our initial experience with real-time MRI-guided cryoablation of small renal tumors using a prototype balanced steady-state free precession imaging sequence in a closed-bore 1.5-T MRI system.

MATERIALS AND METHODS

From August 2008 to April 2012, 18 patients underwent MRI-guided cryoablation of small renal tumors. A 1.5-T cylindrical MRI scanner with a 125 cm × 70 cm bore and a prototype balanced steady-state free precession sequence (BEAT interactive real-time tip tracking) were used to guide the placement of 17-gauge cryoprobes in real time. Ice ball formation was monitored every 3 minutes in 1 or more imaging planes. Each ablation consisted of 2 freeze-thaw cycles. Contrast-enhanced MRI was performed after the second active thaw period. Follow-up consisted of clinical evaluation and renal protocol computed tomography (CT) or MRI performed at 1, 6, 12, 18, and 24 months and annually thereafter.

RESULTS

During the study period, we successfully ablated 18 tumors in 18 patients in 18 sessions. The mean tumor size was 2.2 cm (median, 2 cm; range, 1.2-4.4 cm). The number of cryoprobes used per patient was determined based on tumor size. The mean number of cryoprobes used per patient was 3 (median, 3 cryoprobes; range, 2-4 cryoprobes). Fifty-six cryoprobes, 9 biopsy needles, and 2 hydrodissection needles were successfully placed under real-time MRI guidance using BEAT interactive real-time tip tracking sequence. Hydrodissection under MRI guidance was successfully performed in 4 patients. In each patient, contrast-enhanced MRI performed after the second active thaw period revealed a sharply defined avascular zone surrounding the targeted tumor, which confirmed complete ablation of the tumor with adequate margins. Although contrast media slowly accumulated in the targeted tumor in 9 patients immediately after the procedure, follow-up imaging studies performed at a mean of 16.7 months revealed no contrast enhancement within the ablation zone in these patients. Disease-specific, metastasis-free, and local recurrence-free survival rates were all 100%.

CONCLUSIONS

Real-time placement and manipulation of cryoprobes during MRI-guided cryoablation of small renal tumors in a closed-bore, high-magnetic field scanner are feasible. Technical and clinical success rates are similar to those of patients who undergo CT-guided radiofrequency ablation or cryoablation of small renal tumors. Our findings suggest that MRI-guided ablation has several advantages over CT-guided ablation, including real-time guidance for probe placement, multiplanar imaging, exquisite soft tissue contrast, and lack of ionizing radiation.

Contrast-enhanced ultrasonography for real-time monitoring of interstitial laser thermal therapy in the focal treatment of prostate cancer

INTRODUCTION

We report a case study of the application of contrast-enhanced ultrasonography (CEUS) for intraoperative monitoring of thermal ablation of a single focus of prostate cancer.

METHODS

A patient presented with biopsy-proven, solitary-focus, low-risk prostate cancer and was recruited into a clinical trial of interstitial laser thermal focal therapy. Multiparametric magnetic resonance imaging (MRI) was used to locate the single dominant focus, and photothermal ablation was performed at the tumour site under the guidance of transrectal ultrasonography. Transrectal CEUS using systemic bolus injections of the intravascular contrast agent Definity was performed immediately before, several times during and on completion of therapy. Lesions observed on CEUS were compared with treatment effect as measured by tissue devascularization on 1-week gadolinium (Gd)-enhanced MRI.

RESULTS

Baseline images showed CEUS contrast-agent signal throughout the prostate. During and after treatment, large hypocontrast regions were observed surrounding the treatment fibres, indicating the presence of an avascular lesion resulting from photothermal therapy. Lesion size was found to increase during the delivery of thermal energy. Lesion size measured using CEUS (16 x 11 mm) was similar to the 7-day lesion measured using Gd-enhanced T(1)-weighted MRI.

CONCLUSION

Focal therapy for prostate cancer requires both complete treatment of the dominant tumour focus and minimal morbidity. The application of CEUS during therapy appears to provide an excellent measure of the actual treatment effect. Hence, it can be used to ensure that the therapy encompasses the whole target but does not extend to surrounding critical structures. Future clinical studies are planned with comparisons of intraoperative CEUS to Gd-enhanced MRI at 7 days and whole-mount pathology samples.

Non-surgical treatment of pulmonary and extra-pulmonary metastases

Studies have demonstrated that chemotherapy alone is usually unsuccessful as exclusive therapy for osteosarcoma (Cancer 95:2202-2201, 2002). Information will be presented for situations where non-surgical alternatives could be considered as useful, if not necessary, adjuncts to chemotherapy. In the thorax these include treatment of pleural effusions, chest wall lesions, central lung or mediastinal osteosarcoma, as well as recurrences in patients with limited pulmonary reserve. Other situations include too many metastases to easily resect, axial osteosarcomas, bone metastases, liver and brain metastases. Non-surgical local control measures include radiation with chemotherapy for radiosensitization, bone-seeking radioisotopes (e.g., 153Sm-EDTMP, 223Ra), bisphosphonates, heat (radiofrequency ablation), freezing and thawing (cryoablation), and intracavitary or regional (aerosol) therapy. Because of the predictable and common pattern of pulmonary metastases in osteosarcoma, aerosol therapy also offers an attractive regional treatment strategy. Principles and use of aerosol cytokines (e.g., GM-CSF, IL-2), and aerosol chemotherapy with gemcitabin will be discussed. Individual cases illustrating strategy and techniques will be presented.

Recurrent, refractory, metastatic and/or unresectable pediatric sarcomas: treatment options for young people ‘off the roadmap’

Although sarcoma surgery is very important for cancer control, it is not always possible or practical to offer in some situations, including sarcoma recurrences, metastatic disease and/or unacceptable loss of function. We review some pragmatic approaches and examples of how to balance indications, risks and alternatives to control cancer in young people with sarcomas that are no longer using ‘front-line’ therapy. Radiotherapy combined with chemotherapy and outpatient ‘continuation’ chemotherapy regimens using drugs that cause less alopecia can improve function and quality of life. Some effective strategies to help cope when cure is not possible may include tumor ablation techniques performed in interventional radiology and percutaneous nerve blocks. Family centered care and effective problem solving of difficult issues can be greatly facilitated by consultation with a multidisciplinary team experienced in the management of very difficult cases. Treatment of young people with recurrent, relapsed and/or metastatic sarcoma still remains an art very much in the realm of compassion not protocol and persistent advocacy is required for the young person for whom cure may not be possible. A reduction of suffering and assistance in writing more chapters of a rich life narrative is the goal.

Unexpected Atypical Findings on CT after Radiofrequency Ablation for Small Renal-cell Carcinoma and the Role of Percutaneous Biopsy

Radiofrequency ablation is a safe and effective treatment for small renal-cell carcinoma (RCC) in selected patients. After ablation, computed tomography or magnetic resonance imaging is used to confirm complete eradication or the presence of residual unablated tumor. The characteristic findings associated with these imaging techniques have been described previously. When the appearance of the ablated tumor deviates from expected findings, percutaneous biopsy is necessary to further evaluate the ablation zone. The present report describes three patients whose atypical findings after ablation of small RCC prompted percutaneous biopsy.