Characterization of Microwave Generator Energy and Ablation Volumes Following Transarterial Embolization in an In Vivo Porcine Liver Model

PURPOSE

This study aims to characterize the relationship between ablation zone volume (AZV) and microwave ablation (MWA) energy in an in vivo porcine liver model following arterial embolization.

MATERIALS AND METHODS

With animal IRB approval, eleven female swine underwent either right (n= 5) or left (n= 6) hepatic artery embolization under fluoroscopic guidance. Subsequently, ultrasound guided MWA was performed in each liver segment (left lateral, left medial, right medial, right lateral) at either 30 Watts (W) (n=4 lobes), 60W (n=4), 65W (n=20), 90W (n=8), 120W (n=4), or 140W (n=4) continuously for 5 minutes. Post-procedural volumetric segmentation was performed on standardized multiphase T1 MRI sequences.

RESULTS

AZVs in embolized lobes (15.8 ± 10.6 mL) were significantly larger than non-embolized lobes (11.2 ± 6.5 mL, P <0.01). MWA energy demonstrated significant positive linear correlation with both embolized (R2=0.66, P <0.01) and non-embolized lobes (R2=0.64, P < 0.01). The slope of the linear models corresponded to a 0.95 ± 0.16 and 0.54 ± 0.09 mL/kJ increase in ablation volume per applied kJ of energy (E) in embolized and non-embolized lobes, respectively. In the multivariate model, embolization status significantly modified the relationship between E and AZV as described by the interaction term: 0.42*E*(Embolization Status), (P = 0.031).

CONCLUSION

Linear models demonstrate a near 1.8 fold increase in ratio of AZV per unit E, R(AZV:E), when applied to embolized lobes relative to non-embolized lobes. Absolute AZV differences between embolized and non-embolized lobes were greater at higher power MWA.

Harnessing the abscopal effect for gastrointestinal malignancies in the era of immunotherapy

Gastrointestinal (GI) cancers are among the leading causes of cancer-related mortality and have traditionally been treated using a combination of surgical resection and chemoradiotherapy (CRT). While the introduction of immunotherapies over the last decade have dramatically changed the treatment landscape for some GI malignancies, including esophageal, gastric, and colorectal cancer, treatment resistance remains a major unaddressed obstacle for many patients. There has thus been emerging interest in determining the optimal treatment strategy for the delivery of immunotherapy in combination with traditional therapies. In this regard, a growing number of preclinical and clinical studies have suggested that combining radiation therapy (RT) with immunotherapy may work synergistically to improve treatment response through amplification of the abscopal effect. In this review, we discuss the rationale for RT in combination with immunotherapy. We further discuss how this knowledge may lead to a paradigm shift in the application of RT and highlight remaining issues pertaining to the delivery of combination therapy.

Dynamic Contrast-Enhanced MR Imaging Evaluation of Perfusional Changes and Ablation Zone Size after Combination Embolization and Ablation Therapy

PURPOSE

The objectives of this study were to assess the utility of dynamic contrast-enhanced magnetic resonance (MR) imaging in quantifying parenchymal perfusional changes after embolization and to characterize the association between pharmacokinetic (PK) parameters and final microwave ablation volume.

MATERIALS AND METHODS

PK parameters from dynamic contrast-enhanced MR imaging were used to quantify perfusional changes in the liver after transarterial embolization of the right or left lobe in a swine liver model (n = 5). Each animal subject subsequently underwent microwave ablation (60 W for 5 minutes) of the embolized and nonembolized liver lobes. Changes in PK parameters from dynamic contrast-enhanced MR imaging were correlated with their respective final microwave ablation volumes in each liver lobe.

RESULTS

Microwave ablation volumes of embolized liver lobes were significantly larger than those of nonembolized liver lobes (28.0 mL ± 6.2 vs 15.1 mL ± 5.2, P < .001). PK perfusion parameters were significantly lower in embolized liver lobes than in nonembolized liver lobes (K^trans = 0.69 min^-1 ± 0.15 vs 1.52 min^-1 ± 0.37, P < .001; k_ep = 0.69 min^-1 ± 0.19 vs 1.54 min^-1 ± 0.42, P < .001). There was a moderate but significant correlation between normalized k_ep and ablation volume, with each unit increase in normalized k_ep corresponding to a 9.8-mL decrease in ablation volume (P = .035).

CONCLUSIONS

PK-derived parameters from dynamic contrast-enhanced MR imaging can be used to quantify perfusional changes after transarterial embolization and are directly inversely correlated with final ablation volume.

North American Practice-Based Recommendations for Transjugular Intrahepatic Portosystemic Shunts in Portal Hypertension

Complications of portal hypertension, including ascites, gastrointestinal bleeding, hepatic hydrothorax, and hepatic encephalopathy, are associated with significant morbidity and mortality. Despite few high-quality randomized controlled trials to guide therapeutic decisions, transjugular intrahepatic portosystemic shunt (TIPS) creation has emerged as a crucial therapeutic option to treat complications of portal hypertension. In North America, the decision to perform TIPS involves gastroenterologists, hepatologists, and interventional radiologists, but TIPS creation is performed by interventional radiologists. This is in contrast to other parts of the world where TIPS creation is performed primarily by hepatologists. Thus, the successful use of TIPS in North America is dependent on a multidisciplinary approach and technical expertise, so as to optimize outcomes. Recently, new procedural techniques, TIPS stent technology, and indications for TIPS have emerged. As a result, practices and outcomes vary greatly across institutions and significant knowledge gaps exist. In this consensus statement, the Advancing Liver Therapeutic Approaches group critically reviews the application of TIPS in the management of portal hypertension. Advancing Liver Therapeutic Approaches convened a multidisciplinary group of North American experts from hepatology, interventional radiology, transplant surgery, nephrology, cardiology, pulmonology, and hematology to critically review existing literature and develop practice-based recommendations for the use of TIPS in patients with any cause of portal hypertension in terms of candidate selection, procedural best practices and, post-TIPS management; and to develop areas of consensus for TIPS indications and the prevention of complications. Finally, future research directions are identified related to TIPS for the management of portal hypertension.

Percutaneous direct puncture and embolization of vascularly inaccessible abdominal visceral pseudoaneurysms: A single-center experience and literature review

BACKGROUND

To evaluate the techniques, efficacy, and safety for treating vascularly inaccessible abdominal visceral pseudoaneurysms by direct puncture and embolization.

METHODS

A retrospective study of 5 consecutive patients who underwent percutaneous direct puncture embolization for intra-abdominal pseudoaneurysms in our institution between January 2009 and December 2016. Technical aspects, success, clinical outcome, and complications were discussed.

RESULTS

Four patients (80%) were men, and the mean age of all five patients was 57.2 years (range, 47-72 years). The mean diameter of the pseudoaneurysms was 2.5 cm (range, 1.9-3.4 cm). All the pseudoaneurysms were punctured under the imaging guidance of fluoroscopy, ultrasound, or computed tomography. Coils and glue were used in four of the patients, the remaining one with coil only. The mean injected glue volume was 1.5 (range, 0.8-2) mL. The overall technical and clinical success rate was 100% without major complications or mortality.

CONCLUSION

Our single-center experience and the literature review demonstrate that percutaneous direct puncture embolization is feasible and effective to serve as an alternative for treating abdominal vascular pseudoaneurysms when the traditional endovascular embolization fails. In this approach, fluoroscopy is the most needed guidance technique.

Consensus Guidelines for the Definition of Time-to-Event End Points in Image-guided Tumor Ablation: Results of the SIO and DATECAN Initiative

There is currently no consensus regarding preferred clinical outcome measures following image-guided tumor ablation or clear definitions of oncologic end points. This consensus document proposes standardized definitions for a broad range of oncologic outcome measures with recommendations on how to uniformly document, analyze, and report outcomes. The initiative was coordinated by the Society of Interventional Oncology in collaboration with the Definition for the Assessment of Time-to-Event End Points in Cancer Trials, or DATECAN, group. According to predefined criteria, based on experience with clinical trials, an international panel of 62 experts convened. Recommendations were developed using the validated three-step modified Delphi consensus method. Consensus was reached on when to assess outcomes per patient, per session, or per tumor; on starting and ending time and survival time definitions; and on time-to-event end points. Although no consensus was reached on the preferred classification system to report complications, quality of life, and health economics issues, the panel did agree on using the most recent version of a validated patient-reported outcome questionnaire. This article provides a framework of key opinion leader recommendations with the intent to facilitate a clear interpretation of results and standardize worldwide communication. Widespread adoption will improve reproducibility, allow for accurate comparisons, and avoid misinterpretations in the field of interventional oncology research. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Liddell in this issue.

Effects of irreversible electroporation on femoral nerves in a rabbit model

INTRODUCTION

Irreversible electroporation (IRE) is a novel technique that uses a non-thermal ablation to avoid adjacent major structure injury. The aim of this study was to sequentially evaluate the effects of IRE on the femoral nerve during acute-to-delayed periods in a rabbit model.

MATERIAL AND METHODS

Ultrasound-guided IRE of femoral neurovascular bundles was performed in seven rabbits. Functional and histopathologic evaluation was performed sequentially after IRE. The extent of nerve fiber affected, and the proportion of perineurial inflammation and surrounding tissue injury were recorded.

RESULTS

After IRE, femoral nerve function was damaged before four weeks, but then gradually returned to normal. Perineural inflammatory cell infiltration was most severe three days after IRE (80-85%), and was normalized after eight weeks. Surrounding tissue injury was prominent at three days and one week after IRE (80-90%), and then gradually recovered. However, peripheral nerve fibers were markedly damaged at one and two weeks (80-100%). Nerve fibers then recovered and were normalized at eight weeks.

CONCLUSION

Nerve tissue injury with transient functional impairment can occur after IRE. However, endoneurial and epineurial extracellular matrix were preserved with Schwann cell regeneration, which could lead to regeneration of nerve tissues within eight weeks.

Outcomes of balloon occlusion in the University of California Morbidly Adherent Placenta Registry

BACKGROUND

Morbidly adherent placenta, also known as placenta accreta spectrum, is associated with severe maternal morbidity and mortality. Multiple adjunctive procedures have been proposed to improve outcomes, and at many institutions, interventional radiologists will play a role in assisting obstetricians in these cases.

OBJECTIVE

The objective of the study was to evaluate the outcomes of women with morbidly adherent placenta who underwent cesarean hysterectomy with aortic balloon occlusion or internal iliac artery balloon occlusion catheters, compared with cesarean hysterectomy with surgical ligation of the iliac arteries, or cesarean hysterectomy without adjunctive procedures.

STUDY DESIGN

A retrospective review of women with morbidly adherent placenta treated with cesarean hysterectomy was performed at 5 institutions from May 2014 to April 2018. The balloon occlusion group had either prophylactic aortic or iliac balloons placed prior to cesarean hysterectomy. Comparison groups included those who underwent internal iliac artery ligation prior to hysterectomy or a control group if they underwent cesarean hysterectomy without adjuvant procedures. Evaluated outcomes include estimated blood loss, transfusion requirements, intensive care unit admission, and adverse event rates.

RESULTS

There were 171 women with morbidly adherent placenta included in the study. Twenty-eight had balloon placement prior to cesarean hysterectomy, 18 had intraoperative internal iliac artery ligation, and there were 125 control women who underwent cesarean hysterectomy without any adjunctive procedures. Compared with the women who underwent cesarean hysterectomy without adjunctive procedures, women who underwent aortic or iliac artery balloon occlusion prior to hysterectomy had significantly lower estimated blood loss (30.9% decrease, P < .001), transfusion requirements (76.8% decrease, P < .001), intensive care unit admission rates (0% vs 15.2%, P < .001), and intensive care unit stay lengths (0.0 vs 3.1 days, P < .001). Compared with women who underwent surgical ligation of the internal iliac arteries prior to hysterectomy, women who underwent aortic or iliac artery balloon occlusion prior to cesarean hysterectomy had lower estimated blood loss (54.2% decrease, P < .01), transfusion requirements (90.5% decrease, P < .001), operating room times (40.0% decrease, P < .01), intensive care unit admissions rates (0% vs 77.8%, P < .001), intensive care unit stay lengths (0.0 vs 1.4 days, P < .001), and adverse events (3.6% vs 44.4%, P < .01).

CONCLUSION

Aortic and iliac artery balloon occlusion are associated with lower estimated blood loss, transfusion requirements, intensive care unit admission rates, and adverse event rates compared with women who underwent internal iliac artery ligation prior to cesarean hysterectomy or women who had no adjunctive interventions prior to cesarean hysterectomy for morbidly adherent placenta.

Transfemoral Venous Access Facilitates Upper Extremity Dialysis Interventions: Procedural Success and Clinical Outcomes

PURPOSE

To report technical success and clinical outcomes of transfemoral venous access for upper extremity dialysis interventions.

MATERIALS AND METHODS

A total of 15 patients underwent a transfemoral venous approach for fistulography (n = 4; 27%) or thrombectomy (n = 11; 73%) over a 14-month period. Access characteristics, sheath size, thrombectomy method, angioplasty site, fluoroscopy time, radiation dose, technical and clinical success, complications, and post-intervention primary and secondary patency rates were recorded.

RESULTS

Access type included arteriovenous fistulas (n = 10; 67%) and grafts (n = 5; 33%). The most common configuration was brachio-brachial (n = 6; 38%). Mean age of access was 37 months. Mean prior interventions were 4. Right CFV access was used in all patients using 6-8-French (most common: 7-French [n = 10; 67%]) sheaths. Most thrombectomies (n = 11; 73%) required both pharmacologic and mechanical maceration (n = 9; 82%). All accesses required angioplasty to treat underlying stenosis at the outflow vein (n = 12; 80%) or arteriovenous anastomosis (n = 9; 90%). Mean fluoroscopy time was 26.43 min. Air kerma and dose area product were 178.06 ± 225.77 mGy and 57,768.83 ± 87,553.29 μGym², respectively. Procedural and clinical success rates were 93% and 80%, respectively. Technical failure was due to persistent stenosis in one patient. Clinical failure was due to unsuccessful dialysis immediately following intervention in three patients. Mean post-intervention primary patency and secondary patency durations were 2.8 and 4.8 months, respectively. Primary patency rates at 1 and 3 months were 50% and 35%, respectively. Secondary patency rates at 1 and 3 months were 58% and 30%, respectively.

CONCLUSION

A transfemoral venous approach for intervention of upper extremity dialysis accesses may be a valuable adjunct to traditional approaches.

Yttrium-90 Radioembolization for Metastatic Colorectal Cancer: Outcomes by Number of Lines of Therapy

Metastatic colorectal cancer represents the most common liver malignancy, and imparts a very poor prognosis for those who develop this disease. Unlike primary liver tumors such as hepatocellular carcinoma, which largely develops in patients with underlying cirrhosis, most metastatic liver tumor patients have normal underlying liver function. Owing to this, most will succumb to tumoral replacement of the liver rather than from underlying liver dysfunction. Radioembolization represents a treatment modality that can be used in multiple fashions to treat one or both lobes of the liver. Techniques depend on whether the procedure is used as first-line, second/third-line, or as salvage therapy. Outcomes and complications of radioembolization are presented in this article, as well as background information on colorectal cancer and systemic therapies.

Renal Denervation: A Novel Therapy at the Crossroads of Imaging, Intervention, and Innovation

Hypertension (HTN) is one of the most significant medical problems affecting society today. The estimated 76 million Americans with hypertension represent a significant public health problem, contributing to cardiac, vascular, renal, and neurovascular morbidity and mortality. HTN is the most common indication for lifelong pharmacologic treatment, mainly because of the incontrovertible reductions in cardiovascular events with blood pressure (BP) reduction and control. However, despite the availability and potency of multiple different antihypertensive drugs, up to half of American patients have BPs above the recommended target. Given the overwhelming evidence of both the cost to society of HTN and the benefits that are accrued from improved BP control, alternatives or adjuncts to current management options have been sought to aid in treatment of these patients. Over the past few years, a device-based approach involving modulation of the autonomic nervous system, termed renal denervation, has evolved to meet this challenge. With early trials showing startlingly good results, with few side effects, multiple devices were fast-tracked to clinical trials and hence to the market. However, larger trials have shone an unfavorable light on the field, with concerns about the short- and long-term effectiveness, diverting attention back to operational and procedural details. Despite this, image-guided manipulation of the sympathetic nervous system to treat HTN remains a fertile area of laboratory and clinical research.

Irreversible electroporation: ready for prime time?

Image-guided ablation has evolved rapidly in the past decade into a competitive technique for treating focal solid malignancies. However, as they rely mainly on thermal energy, such as radiofrequency or microwave, many tumors close to sensitive organs, such as ducts, bowel, and nerves, still remain nonablatable owing to the risk of thermal injury. Irreversible electroporation is a novel ablation modality that relies largely on a nonthermal mechanism to induce cell death, and therefore may overcome many of the shortcomings of thermal ablation. Emerging preclinical data as well as early clinical experience is showing promise for this technique in treating a variety of tumors including periportal liver masses, pancreatic cancer, perihilar renal tumors, prostate cancer, and other soft tissue tumors. However, practical limitations remain for irreversible electroporation, and its complete cancer and location-specific safety and efficacy profiles are still largely unknown. We therefore review what is known for this new ablation modality based on preclinical and preliminary clinical data, and discuss its emerging indications as well as technical challenges.

Suppression of stent-induced tissue hyperplasia in rats by using small interfering RNA to target matrix metalloproteinase-9

BACKGROUND AND STUDY AIMS

We evaluated the efficacy of small interfering RNA (siRNA) in targeting matrix metalloproteinase (MMP-9) to suppress stent-induced tissue hyperplasia in a rat esophageal model.

METHODS

The silencing effect of the candidate siRNA (termed (MMP-9 siRNA) was evaluated in 9 L rat glial cells. Four groups of rats (n = 10, each group) were used: Eso-S, stent insertion only, comparison; Eso-R, stent insertion plus treatment with MMP-9 siRNA complexed with Chol-R9 for delivery, experimental; Eso-P, stent insertion plus treatment with pCMV-luc complexed with Chol-R9, for confirmation of Chol-R9 delivery effect; and Eso-N, no stent insertion and no treatment, controls. All rats were sacrificed at 3 weeks. The therapeutic efficacy of the MMP-9 siRNA/Chol-R9 complex was assessed.

RESULTS

The most potent MMP-9 siRNA was selected. Compared with the Eso-S group, the Eso-R group showed significantly less tissue hyperplasia with a lower percentage of granulation tissue and smaller granulation tissue area, and also significantly lower MMP-9 level.

CONCLUSIONS

MMP-9 siRNA/Chol-R9 is effective for inhibiting stent-induced tissue hyperplasia in a rat esophageal model.

Therapy model for advanced intracerebral B16 mouse melanoma using radiation therapy combined with immunotherapy

A reproducible therapy model for advanced intracerebral B16 melanoma is reported. Implanted tumors (D0), suppressed by a single 15 Gy radiosurgical dose of 100 kVp X-rays (D8), were further suppressed by a single ip injection of a Treg-depleting mAb given 2 days prior to the initiation (D9) of four weekly then eight bi-monthly sc injections of GMCSF-transfected, mitotically disabled B16 cells. The trends of seven independent experiments were similar to the combined result: The median (days) [SD/total N] of survival went from 15[1.09/62] (no treatment control) to 35.8[8.8/58] (radiation therapy only) to 52.5[13.5/57] (radiation therapy plus immunotherapy). Within 2 weeks after immunization, tumors in mice receiving radiation therapy plus immunotherapy were significantly smaller than tumors in mice treated only with radiosurgery. Splenocytes and lymph node cells from immunized mice showed increased interferon γ production when cultured with syngeneic tumor cells. We suggest that our model will be useful for the development and testing of novel combination therapies for brain tumors.

Abstract 4748: Therapy model for advanced intracerebral B16 mouse melanoma using radiosurgery combined with immunotherapy

A reproducible therapy model for advanced intracerebral B16 melanoma is reported. Implanted tumors (D0), suppressed by a single 15 Gy radiosurgical dose of 100 kVp X-rays (D8) were further suppressed by a single ip injection of a Treg depleting Mab given two days prior to the initiation (D9) of four weekly then eight bi-monthly sc injections of GMCSF-transfected, mitotically disabled B16 cells. The results of seven independent experiments were similar to the combined result: the Median (Days) [SD/Total N] of survival went from 15[1.09/62] (No Treatment Control) to 35.8[8.8/58] (Radiosurgery-Only) to 52.5[13.5/57] (Radiosurgery Plus Immunotherapy); Radiosurgery-Only and Radiosurgery Plus Immunotherapy groups were highly distinct from Controls as well as from one another (p&lt;0.0001). Within two weeks after immunization, tumors in mice receiving Radiosurgery Plus Immunotherapy were significantly smaller than tumors in mice treated only with Radiosurgery. Splenocytes and lymph node cells from immunized mice showed increased interferon Y production when cultured with syngenic tumor cells. We hypothesize that our model will be useful for the development and testing of novel combination therapies for brain tumors.

Citation Format: Henry M. Smilowitz, Dan Sasso, Edward W. Lee, Peggy Micca, Gyuhyeong Goh, F Avrahamn Dilmanian. Therapy model for advanced intracerebral B16 mouse melanoma using radiosurgery combined with immunotherapy. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4748. doi:10.1158/1538-7445.AM2013-4748

Image-guided tumor ablation: emerging technologies and future directions

As the trend continues toward the decreased invasiveness of medical procedures, image-guided percutaneous ablation has begun to supplant surgery for the local control of small tumors in the liver, kidney, and lung. New ablation technologies, and refinements of existing technologies, will enable treatment of larger and more complex tumors in these and other organs. At the same time, improvements in intraprocedural imaging promise to improve treatment accuracy and reduce complications. In this review, the latest advancements in clinical and experimental ablation technologies will be summarized, and new applications of image-guided tumor ablation will be discussed.

Electron microscopic demonstration and evaluation of irreversible electroporation-induced nanopores on hepatocyte membranes

PURPOSE

To demonstrate, evaluate, and verify the existence of irreversible electroporation (IRE)-ablation induced nanopores on the plasma membrane of hepatocytes.

MATERIALS AND METHODS

On animal research committee approval, four New Zealand rabbits and two Yorkshire swine underwent IRE ablation of the liver (90 pulses, 100 μs per pulse at 2,500 V), and selected ablated liver tissues were harvested, fixed, and air-dried according to the electron microscopy (EM) protocol. A scanning electron microscope (SEM; Nova 230 NanoSEM [FEI, Hillsboro, Oregon] with 80 picoamperes and 10-kV acceleration) was used to visualize and verify IRE-created nanopores. Using NIH image (Bethesda, Maryland) and ImageScope (Aperio Inc., Vista, California), 21 ablated tissues (16 rabbit, 5 swine) were evaluated. Corresponding hematoxylin and eosin (H&E) evaluation was performed to verify IRE-induced cell death.

RESULTS

In all 21 IRE-ablated tissues, the SEM was able to show numerous, well-circumscribed, round, and concave-shaped pore defects disturbing the hepatocyte plasma membranes. These pores were not seen in normal liver. The size of the nanopores ranged from 80-490 nm with the greatest frequency of pores in bimodal distribution. The highest frequency of pore size was noted at the size range 340-360 nm.

CONCLUSIONS

IRE induces nanopores on hepatocyte membranes, as shown by SEM. The pore diameters are larger than nanopores created by reversible electroporation (RE), which may have implications for irreversibility or permanency.

Percutaneous ablation of hepatocellular carcinoma: current status

Hepatocellular carcinoma (HCC) is an increasingly common disease with dismal long-term survival. Percutaneous ablation has gained popularity as a minimally invasive, potentially curative therapy for HCC in nonoperative candidates. The seminal technique of percutaneous ethanol injection has been largely supplanted by newer modalities, including radiofrequency ablation, microwave ablation, cryoablation, and high-intensity focused ultrasound ablation. A review of these modalities, including technical success, survival rates, and complications, will be presented, as well as considerations for treatment planning and follow-up.

Irreversible electroporation: a novel image-guided cancer therapy

Irreversible electroporation (IRE) is a novel tumor ablation technique using a non-thermal energy to create innumerable permanent nanopores in the cell membrane to disrupt cellular homeostasis. This disruption of cellular homeostasis initiates apoptosis which leads to permanent cell death. In our translational research, we have demonstrated that IRE can be a safe, fast and powerful method of tumor treatment. In this review, we present an overview of IRE ablation including a brief history of IRE, advantages and disadvantages of IRE and clinical and research implications of IRE.

Advanced hepatic ablation technique for creating complete cell death: irreversible electroporation

PURPOSE

To evaluate the effectiveness of irreversible electroporation (IRE) in hepatic tissue ablation and the radiologic-pathologic correlation of IRE-induced cell death.

MATERIALS AND METHODS

On approval of the animal research committee, 16 Yorkshire pigs underwent ultrasonography (US)-guided IRE of normal liver. A total of 55 ablation zones were created, which were imaged with US, magnetic resonance (MR) imaging, and computed tomography (CT) and evaluated with immunohistochemical analysis, including hematoxylin-eosin (H-E), Von Kossa, and von Willibrand factor (vWF) staining and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.

RESULTS

At gross section examination, the mean diameter of the ablation zones was 33.5 mm + or - 3.0 (standard deviation) and was achieved in 6.9 minutes (mean total procedure time per ablation), with a mean difference of 2.5 mm + or - 3.6 between US and gross section measurements (r = 0.804). No complications were seen in any of the 16 animals. IRE ablation zones were well characterized with US, CT, and MR imaging, and real-time monitoring was feasible with US. H-E, Von Kossa, and vWF staining showed complete cell death, with a sharply demarcated treatment area. Bile ducts and vessels were completely preserved. Areas of complete cell death were stained positive for apoptotic markers (TUNEL, BCL-2 oncoprotein), suggesting involvement of the apoptotic process in the pathophysiology of cell death caused by IRE.

CONCLUSION

In an animal model, IRE proved to be a fast, safe, and potent ablative method, causing complete tissue death by means of apoptosis. Cell death is seen with full preservation of periablative zone structures, including blood vessels, bile ducts, and neighboring nonablated tissues.

How diagnostic is ultrasound-guided neck mass biopsy (fine-needle capillary sampling biopsy technique)?: evaluation of 132 nonthyroid neck mass biopsies with pathologic analysis over 7 years at a single institution

OBJECTIVE

The purpose of this study was to evaluate the diagnostic value of ultrasound-guided neck mass biopsy (fine-needle capillary sampling biopsy [FNC] technique).

METHODS

With Institutional Review Board approval, all patients who had an ultrasound-guided neck mass FNC biopsy between January 2000 and December 2006 were retrieved from the ultrasound database. A total of 132 neck mass biopsies were performed in 124 patients. Patient demographics, procedure characteristics, and pathologic diagnoses were recorded.

RESULTS

Of the 124 patients, 73 were female (mean age, 51.4 years). Biopsies were performed twice in 8 patients. A significant 200% increase from 2000 through 2002 to 2003 through 2004 and from 2003 through 2004 to 2005 through 2006 was found (P < .05). The most biopsied location was in the lymph nodes (34.8%), followed by perithyroid soft tissue masses (28.0%). A 25-gauge needle was used most frequently (97.7%). A total of 41 biopsies were diagnostic for thyroid diseases (31.1%), with the most common being thyroid papillary carcinoma. We found metastases in 31 biopsies (23.5%). Following these 2 were 29 lymph node biopsies. No major complications were noted. Of the 132 neck masses biopsied, 8 were pathologically nondiagnostic (93.9% diagnostic yield), yielding sensitivity, specificity, and accuracy of greater than 95% (97.1%, 95.2%, and 95.8%, respectively).

CONCLUSIONS

Ultrasound-guided FNC of neck masses is highly diagnostic. The diagnostic yield is especially high for detection of malignancy, including metastases. Together with a high clinical suspicion, ultrasound-guided needle biopsy should be performed to form a correct diagnosis and make appropriate management plans.

Single ZnO nanobelt based field effect transistors (FETs)

Electrical properties of single ZnO nanobelt have been examined by fabricating single nanobelt based field effect transistors (FETs). The ZnO nanobelts were grown via non-catalytic simple thermal evaporation process by using metallic zinc powder in the presence of oxygen. The detailed structural and optical characterizations confirmed that the grown nanobelts are well-crystalline with the wurtzite hexagonal phase and exhibiting good optical properties. The passivation effect on the electrical characteristics of the as-grown nanobelts was also evaluated by passivating the fabricated FETs with polymethyl methacrylate (PMMA). The passivated single ZnO nanobelt based FETs exhibited higher electrical performance as compared to non-passivated FETs due to reduction in the physically absorbed chemisorbed species such as O-, O2-, O2, or OH- etc. The field effect mobility (micro(eff)) of the fabricated nanobelt based non-passivated and passivated FETs was estimated to be approximately 21.3 and 59 cm2/V x s, respectively. Moreover the carrier concentration and peak transconductance of the fabricated non-passivated and passivated FET were calculated to be approximately 8.73 x 10(17) and approximately 1.86 x 10(18) cm(-3) and approximately 0.76 and 1.4 microS, respectively. This work offers substantial opportunities for further practical electronics and photonics nanodevice applications of ZnO based nanostructures.

A new wave in treatment of vascular occlusive disease: biodegradable stents--clinical experience and scientific principles

Stent-based therapies in percutaneous vascular intervention are associated with significant long-term complications related to in-stent restenosis. A growing body of literature demonstrates the feasibility of biodegradable materials for endovascular stents, which may, in theory, circumvent many of the immunologic and inflammatory response issues seen with long-term metallic stent failure in coronary and peripheral applications. This review describes the history of endovascular stents and the challenges encountered with metallic, drug-eluting, and biodegradable stents. A review of the basic engineering principles of biodegradable stents is provided, along with a discussion of the cellular mechanisms of restenosis.

Bronchial and pulmonary arterial and venous interventions

With advancement of interventional techniques and increasing complexity of patients, the involvement of interventional radiologists in the pulmonary critical care (PCC) setting has increased in recent years. Particularly, interventional radiologists have evolved to play a significant role in treating patients with vascular pathologies such as massive pulmonary embolism. In this article, we discuss management of these critically ill patients using four pulmonary and bronchial vascular interventional procedures: bronchial artery embolization in the setting of hemoptysis; pulmonary artery embolization in the setting of the treatment of AVM; thrombectomy and thrombolysis of the pulmonary arteries for the treatment of pulmonary embolism; and catheter-directed stent placement in the treatment of superior vena cava syndrome.

Comparison between the electrical properties of ZnO nanowires based field effect transistors fabricated by back- and top-gate approaches

Large-quality, well-crystallized growth of ZnO nanowires was done via non-catalytic thermal evaporation process on silicon substrate only by using metallic zinc powder and oxygen as source materials for zinc and oxygen, respectively. The electrical properties of the as-grown ZnO nanowires were examined by fabricating a single nanowire based FETs which were fabricated via two approaches, i.e., back- and top-gate approaches by using electron beam lithography (EBL) and photolithography processes. ZnO FETs electrical properties were characterized by I(DS)-V(DS) and I(DS)-V(GS) measurement. The fabricated single ZnO nanowire based FETs by back- and top-gate approaches exhibited field effect mobilities of approximately 4.25 and approximately 12.76 cm2/Vs, respectively. Moreover, the carrier concentrations for the fabricated back- and top-gate FETs were approximately 1.6 x 10(17) and approximately 1.37 x 10(18) cm(-3), respectively. From our studies it was observed that the fabricated top-gate FETs exhibited higher and good electrical properties as compared to ZnO nanowire FETs fabricated using back-gate approaches.

Imaging guided percutaneous irreversible electroporation: ultrasound and immunohistological correlation

Preliminary results of percutaneous irreversible electroporation (PIE) on swine liver as a novel non-thermal ablation are presented. The goal of this study was to evaluate the feasibility of using irreversible electroporation in more clinically applicable manner, a percutaneous method, and to investigate a possible role of apoptosis in PIE-induced cell death. We performed PIE on four swine livers under real-time ultrasound guidance. The lesions created by PIE were imaged with ultrasound and were correlated with histology data, including pro-apoptotic marker. A total of 11 lesions were created with a mean size of 16.8 cm(3) in 8.4 +/- 1.8 minutes. Real-time monitoring was performed and a correlation of (+) 2 +/- 3.2 mm in measurement comparison between ultrasound and gross pathologic measurements was demonstrated. Complete hepatic cell death without structural destruction, unaffected by heat-sink effect, and with a sharp demarcation between the ablated zone and the non-ablated zone were observed. Immunohistological analysis confirmed complete apoptotic cell death by PIE on Von Kossa, BAX, and H&E staining. In summary, PIE can provide a novel and unique ablative method with real-time monitoring capability, ultra-short procedure time, non-thermal ablation, and well-controlled and focused apoptotic cell death.

Renal and cardiac neuropeptide Y and NPY receptors in a rat model of congestive heart failure

Neuropeptide Y (NPY) is coreleased with norepinephrine and stimulates vasoconstriction, vascular and cardiomyocyte hypertrophy via Y1 receptors (R) and angiogenesis via Y2R. Although circulating NPY is elevated in heart failure, NPY's role remains unclear. Activation of the NPY system was determined in Wistar rats with the aortocaval (A-V) fistula model of high-output heart failure. Plasma NPY levels were elevated in A-V fistula animals (115.7 +/- 15.3 vs. 63.1 +/- 17.4 pM in sham, P < 0.04). Animals either compensated [urinary Na(+) excretion returning to normal with moderate disease (COMP)] or remained decompensated with severe cardiac and renal failure (urinary Na(+) excretion <0.5 meq/day), increased heart weight, decreased mean arterial pressure and renal blood flow (RBF), and death within 5-7 days (DECOMP). Cardiac and renal tissue NPY decreased with heart failure, proportionate to the severity of renal complications. Cardiac and renal Y1R mRNA expression also decreased (1.5-fold, P < 0.005) in rats with heart failure. In contrast, Y2R expression increased up to 72-fold in the heart and 5.7-fold in the kidney (P < 0.001) proportionate to severity of heart failure and cardiac hypertrophy. Changes in receptor expression were confirmed since the Y1R agonist, [Leu31, Pro34]-NPY, had no effect on RBF, whereas the Y2R agonist (13-36)-NPY increased RBF to compensate for disease. Thus, in this model of heart failure, cardiac and renal NPY Y1 receptors decrease and Y2 receptors increase, suggesting an increased effect of NPY on the receptors involved in cardiac remodeling and angiogenesis, and highlighting an important regulatory role of NPY in congestive heart failure.

Neuropeptide Y acts directly in the periphery on fat tissue and mediates stress-induced obesity and metabolic syndrome

The relationship between stress and obesity remains elusive. In response to stress, some people lose weight, whereas others gain. Here we report that stress exaggerates diet-induced obesity through a peripheral mechanism in the abdominal white adipose tissue that is mediated by neuropeptide Y (NPY). Stressors such as exposure to cold or aggression lead to the release of NPY from sympathetic nerves, which in turn upregulates NPY and its Y2 receptors (NPY2R) in a glucocorticoid-dependent manner in the abdominal fat. This positive feedback response by NPY leads to the growth of abdominal fat. Release of NPY and activation of NPY2R stimulates fat angiogenesis, macrophage infiltration, and the proliferation and differentiation of new adipocytes, resulting in abdominal obesity and a metabolic syndrome-like condition. NPY, like stress, stimulates mouse and human fat growth, whereas pharmacological inhibition or fat-targeted knockdown of NPY2R is anti-angiogenic and anti-adipogenic, while reducing abdominal obesity and metabolic abnormalities. Thus, manipulations of NPY2R activity within fat tissue offer new ways to remodel fat and treat obesity and metabolic syndrome.

Crusted Norwegian Scabies in an Adult With Langerhans Cell Histiocytosis

BACKGROUND

Crusted Norwegian scabies is a rare hyperkeratotic variant of scabies infestation. We report herein a case of crusted scabies in a woman with underlying Langerhans cell histiocytosis (LCH).

OBSERVATIONS

A 49-year-old woman with LCH was hospitalized owing to marked thrombocytopenia. Her hyperkeratotic skin eruption was thought to be secondary to LCH because several years earlier, she had positive biopsy findings and had been diagnosed as having LCH. After a 1-month hospital stay, her laboratory values improved despite worsening of her skin lesions.

CONCLUSION

Analysis of skin scrapings confirmed the presence of scabies, and resolution was achieved with a 1-dose ivermectin treatment.

Short-term intraocular pressure trends after intravitreal triamcinolone injection

PURPOSE

To report the trends in intraocular pressures (IOP) within the first week after intravitreal injection of triamcinolone acetonide (Kenalog) for the treatment of retinal disease.

DESIGN

Retrospective chart review.

METHODS

Review of 43 consecutive patients and 50 intravitreal injections of 4 mg triamcinolone acetonide. Analysis of the effect on IOP was performed.

RESULTS

The mean preinjection IOP was 14.60 +/- 3.71 mm Hg (mean +/- SD) (range, 9 to 26 mm Hg). The mean postinjection IOP (30 minutes after injection) was 19.64 +/- 7.43 mm Hg (range, 5 to 45 mm Hg). Mean IOP change before and after injection was 4.83 +/- 7.10 mm Hg. The mean IOP one to two days after injection was 15.32 +/- 4.41. mm Hg (range, 6 to 27 mm Hg). The mean IOP five to seven days after injection was 15.94 +/- 4.86 mm Hg (range, 5 to 28 mm Hg).

CONCLUSIONS

Intravitreal triamcinolone acetonide injection in this limited series does not cause a marked increase in IOP within the first week after the procedure.

Pain Associated With Local Anesthetic Injection in Eyelid Procedures: Comparison of Microprocessor-Controlled Versus Traditional Syringe Techniques

PURPOSE

To evaluate the pain associated with local infiltration of the eyelid, using a microprocessor-controlled delivery system (CompuMed, using the Wand), as compared with traditional manual syringe infiltration technique.

METHODS

A randomized clinical trial of 30 patients undergoing minor eyelid surgical procedures was performed. Fifteen patients were injected by use of the CompuMed system and 15 patients were injected by the traditional manual syringe technique. The severity of pain was recorded from each patient by using a visual analog scale (0 to 10). The duration of pain experienced by the patient was also recorded.

RESULTS

The mean pain level reported was 1.5 in the Wand group and 3.2 in the syringe group (p < 0.01). The mean duration of pain experienced was 1.5 seconds in the Wand group and 34 seconds in the syringe group (p < 0.01).

CONCLUSIONS

The Wand was effective at significantly reducing the pain associated with local anesthetic infiltration in minor eyelid surgical procedures. Patients appear to feel pain from the initial needle stick but not during the actual injection.

The outcome of resection shoulder arthroplasty for recalcitrant shoulder infections

Postarthroplasty infection is a devastating complication. In some patients, virulent pathogens or poor health complicate reconstruction. Resection arthroplasty is a viable option in such cases. Seven patients with resection arthroplasty following infection after shoulder arthroplasty were reviewed retrospectively at an average 20- month follow-up (range, 12-41). Average time between the initial procedure and the first debridement was 59.5 months (4-151 months). The average number of debridements was 2.2 per patient (range, 1-4 procedures). There were no complications, no recurrence of deep infection, no nerve damage, and no fractures. All patients were able to reach the opposite axilla, their backpocket and perineum, and their mouth. All but 1 patient were satisfied with their result. No patient had a satisfactory outcome via Neer's criteria. Resection arthroplasty is a reasonable salvage option for patients who are not good candidates for prosthetic reimplantation. This yields patients who can reliably perform basic activities of daily living.

Differential diagnosis of gastrointestinal bleeding

In this article, we review the many causes of gastrointestinal (GI) bleeding and discuss current strategies for rendering a specific diagnosis. Diagnostic tools considered in this review include: clinical assessment, upper endoscopy, colonoscopy, scintigraphy, and conventional arteriography as well as computed tomography angiography and magnetic resonance angiography. An algorithm for the diagnostic work-up of the patient with GI bleeding is included.

Differential effects of neuropeptide Y on the growth and vascularization of neural crest-derived tumors

Neuropeptide Y (NPY) is a sympathetic neurotransmitter recently found to be potently angiogenic and growth promoting for endothelial, vascular smooth muscle and neuronal cells. NPY and its cognate receptors, Y1, Y2 and Y5, are expressed in neural crest-derived tumors; however, their role in regulation of growth is unknown. The effect of NPY on the growth and vascularization of neuroendocrine tumors was tested using three types of cells: neuroblastoma, pheochromocytoma, and Ewing's sarcoma family of tumors (ESFT). The tumors varied in expression of NPY receptors, which was linked to differential functions of the peptide. NPY stimulated proliferation of neuroblastoma cells via Y2/Y5Rs and inhibited ESFT cell growth by Y1/Y5-mediated apoptosis. In both tumor types, NPY receptor antagonists altered basal growth levels, indicating a regulatory role of autocrine NPY. In addition, the peptide released from the tumor cells stimulated endothelial cell proliferation, which suggests its paracrine angiogenic effects. In nude mice xenografts, exogenous NPY stimulated growth of neuroblastoma tumors, whereas it increased apoptosis and reduced growth of ESFT. However, in both tumors, NPY treatment led to an increase in tumor vascularization. Taken together, this is the first report of NPY being a growth-regulatory factor for neuroendocrine tumors, acting both by autocrine activation of tumor cell proliferation or apoptosis and by angiogenesis. NPY and its receptors may become targets for novel approaches in the treatment of these diseases, directed against both tumor cell proliferation and angiogenesis.

Comparison of SAR (sodium adsorption ratio) between RO and NF processes for the reclamation of secondary effluent

Secondary effluent reclamation and reuse has been considered as an alternative for agricultural irrigation water. Whilst all constituents in the reclaimed wastewater could affect plant growth and soil characteristics, the most important parameters for agricultural irrigation are salinity and SAR (Sodium Adsorption Ratio). Salinity affects the availability of crop water and sodium causes clay soils to disperse. Membrane technologies, especially NF (Nano-Filtration) and RO (Reverse Osmosis), have played in a key role reclaiming the secondary effluent. RO can remove monovalent and divalent cations simultaneously. However NF processes reject preferably divalent cations and most monovalent ions are allowed to pass through the NF membranes. This could make them have different SAR values for both NF and RO processes. Therefore the primary objective of this study is to examine if the SAR values of the reclaimed water could be changed while they undergo NF and RO processes. The measured SAR values of the secondary effluent, NF permeate, and RO permeate were 1.78, 4.67, and 0.72 respectively. The SAR value after NF (4.67) increased to more than twice that of the feed solution, whereas the SAR of the RO permeate decreased to 0.72. In general, the higher SAR the water has, the greater risk the soils have. Although the SAR value after NF was within the safe range, this increased SAR value will affect permeability of soil, thus limiting the reclaimed wastewater use for as agricultural irrigation water. Consequently, when the NF system is used for the reclamation of the secondary effluent, SAR has to be examined first because potentially it tends to increase the SAR value.

Neuropeptide Y: multiple receptors and multiple roles in cardiovascular diseases

Neuropeptide Y (NPY), a sympathetic co-transmitter, acts through multiple G protein-coupled receptors (Y1 to y6) to elicit its vast range of effects in the cardiovascular, immune, and central and peripheral nervous systems. Initially, the focus of the function of NPY in the cardiovascular system involved its acute actions, such as vasoconstriction via the Y1 receptor. However, recent studies have shown that NPY is a potent growth and angiogenic factor, which acts on multiple receptor subtypes. To be more specific, NPY-mediated vascular smooth muscle cell growth, leading to neointima formation, involves Y1 and Y1 receptors, while the angiogenic effects of NPY include Y2 and Y5 receptor activation. The presence of dipeptidyl peptidase IV also influences the cardiovascular responses of NPY by acting as a converting enzyme, shifting NPY activities away from Y1. Thus, agonists and antagonists aimed at the NPY system represent a new avenue for drug treatment, which may help alleviate several cardiovascular disorders in which vascular remodeling plays a major role, such as atherosclerosis, restenosis following balloon angioplasty, hypertension and peripheral vascular disease.

Anatomical study concerning the origin and course of the pectoral branch of the thoracoacromial trunk for the pectoralis major flap

The patterns of the feeding vessels to each muscle determine the extent of their safe transposition and the muscle's value as a pedicled flap in reconstructive surgery. This study aimed to demonstrate the point of origin and the intra- and submuscular course of the pectoral branch of the thoracoacromial trunk (TAT) for pectoralis major (PM) flap surgery. Seventy sides of the PM were dissected based on a clinical reference line that has been used for several decades. The branching point of the TAT from the axillary artery was located lateral to the midclavicular line on the right-sided specimens (100%) and medial to the midclavicular line on the left sides (86%). The branching patterns of the pectoral branch to the PM muscle from the TAT were classified into three types. In type I the pectoral branches originated directly from the TAT (55 cases, 78.6%). In type II (11 cases, 15.7%) and type III (4 cases, 5.7%) the pectoral branch divided from the medial and lateral pedicle of the TAT, respectively. The course of the pectoral branch from the TAT in the PM was categorized into three patterns according to the degree of proximity to the midclavicular line. In 49 cases (70%), the pectoral branch in the PM ran within 1 cm of the midclavicular line. The other cases ran 2 cm (20 cases, 29%) and 3 cm (1 case, 1%) from the midclavicular line, respectively. These results provide topographic data of the pectoral branch based on anatomical landmarks, and will be useful in surgical planning as well as the procedure for PM flap surgery.

Topographic anatomy of the lingual nerve and variations in communication pattern of the mandibular nerve branches

We made a thorough observation of the morphology and course of the lingual nerve (LN) and inferior alveolar nerve (IAN) to clarify their topographical relationships in the infratemporal fossa and in the paralingual area. Thirty-two Korean hemi-sectioned heads were dissected macroscopically and microscopically from a clinical viewpoint. On the 32 tracings on the radiograph, the average distance between the retromolar portion and the LN was 7.8 mm, and no case was found where the LN ran above the alveolar crest as passing along the mandibular lingual plate. The bifurcation of the LN and IAN was located around the mandibular notch, inferior to the otic ganglion in 66% of the cases, and a plexiform branching pattern of the mandibular nerve was observed in only two cases. The bifurcation spot of the LN and IAN was located 14.3 mm inferior to the foramen ovale and 16.5 mm superior to the tip of hamulus. Collateral nerve twigs from the LN to the retromolar area were observed in 26 cases (81.2%), with an average of one nerve twig. We observed four types of variations in terms of communication pattern. In four specimens, the mylohyoid nerve passed through the mylohyoid muscle and connected with the LN. In other four specimens, the IAN communicated with the auriculotemporal nerve. We also observed another type of variational communication between the IAN and the nerve to the lateral pterygoid (LPt); this was observed in only one specimen, and it could be predicted that motor innervation from the nerve to the LPt was transmitted via the mental nerve to the depressor anguli oris. Another type was observed where the IAN divided into two branches with the posterior branch being partially entrapped by the LPt muscle fibers.

Neuropeptide Y and Y2-receptor are involved in development of diabetic retinopathy and retinal neovascularization

BACKGROUND

Neuropeptide Y is a sympathetic neurotransmitter, a potent endothelium-derived angiogenic factor and a vascular mitogen. We have studied the role of the functional leucine7 to proline7 polymorphism of the signal peptide region of preproneuropeptide Y (prepro-NPY) as a genetic susceptibility factor for diabetic retinopathy. In addition, we investigated the role of the NPY Y2-receptor as a putative mediator of angiogenic NPY signaling in the retina.

METHODS

Frequencies of proline7 (Pro7) carriers in the prepro-NPY were determined in type 1 and type 2 diabetes patients having retinopathy, in type 2 diabetes patients without retinopathy and in healthy control subjects. The role of Y2-receptor in hyperoxemia-induced retinal neovascularization was investigated in Y2-receptor knockout mice (Y2-/-) and in rats administered Y2-receptor mRNA antisense oligonucleotide.

RESULTS

The carriers having Pro7 in the preproNPY are markedly over-represented among type 2 diabetes patients with retinopathy compared to type 2 diabetes patients without retinopathy and to the population control. Neonatal exposure to hyperoxia resulted in development of retinal neovascularization that was prevented in Y2(-1-) -mice, and significantly inhibited in rats treated with the Y2-receptor antisense oligonucleotide.

CONCLUSIONS

NPY and Y2-receptor play important roles in diabetic retinopathy and retinal neovascularization and are thus potential new targets for drug molecules for treatment of retinopathy.