EUS-guided interstitial brachytherapy of the pancreas: a feasibility study

History of the Interventional Pancreaticobiliary Endoscopy

With the introduction of endoscopic retrograde cholangiopancreatography and linear endoscopic ultrasound, interventional pancreaticobiliary (PB) endoscopy has had an enormous impact in the management of pancreatic and biliary diseases. Continuous efforts to improve various devices and techniques have revolutionized these treatment modalities as viable alternatives to surgery. In recent years, trends toward combining endoscopic techniques with other modalities, such as laparoscopic and radiological interventions, for complex PB diseases have emerged using a multidisciplinary approach. Ongoing research and clinical experience will lead to refinements in interventional PB endoscopic techniques and subsequently improve outcomes and reduce complication rates.

A meta-analysis on the efficacy of endoscopic ultrasonography for treatment of pancreatic cancer

OBJECTIVE

This study aimed to systematically evaluate the efficacy and safety of Endoscopic Ultrasonography (EUS) for the treatment of pancreatic cancer.

METHODS

The PubMed, Embase, Web of Science, and Google Scholar databases were searched from the inception of the databases to June 2022. RevMan 5.3.0 software was utilized for data analysis. In total, 13 self-descriptive studies, which enrolled 382 patients, were finally included.

RESULTS

It was revealed that EUS for the treatment of pancreatic cancer exhibited a lower incidence of adverse reactions (Relative Risk Ration [RR = 0.23], 95 % Confidence interval [95 % CI 0.23-0.23]), a higher success rate (RR = 0.90, 95 % CI 0.90-0.90), and a low failure rate (RR = 0.06, 95 % CI 0.06-0.06). Moreover, EUS-guided Celiac Plexus Neurolysis (EUS-CPN) not only significantly relieved pancreatic cancer patients' pain (RR = 0.83, 95 % CI 0.83-0.83), but also significantly eliminated pain in some patients (RR = 0.09, 95 % CI 0.09-0.09). The effects of EUS on pancreatic cancer treatment were satisfactory, and few adverse reactions were found.

CONCLUSION

Owing to the restricted sample size in this meta-analysis, primarily consisting of descriptive studies, it was imperative to conduct more rigorously designed, multi-center, long-term follow-up, larger sample, and Randomized Controlled Trials (RCTs) to validate the findings.

The global research status and trends of the application of endoscopic ultrasonography in pancreatic tumors over the last decades: A bibliometric study

Background

To describe the development process and structural relationships of scientific achievements in endoscopic ultrasonography (EUS) in pancreatic tumors over the past decades and to reveal the key research topics using bibliometric analysis.

Methods

All relevant publications covering the research of EUS in pancreatic tumors from 1984 to 2021 were involved through the Web of Science Core Collection. R-bibliometrix was used to conduct the bibliometric analysis, and VOSviewer software was used to explore the hot spots and networks related to this field.

Results

Between 1984 and 2021, 4071 publications were involved. The number of annual publications increased from 1 to 310. The United States contributed the most publications to this field (n=1433, 35.20%), followed by Japan (n=827, 20.31%) and Germany (n=319, 7.84%). There was active cooperation between countries/regions. Gastrointestinal Endoscopy (GIE) was the most productive journal and the most influential journal. Professor Giovannini M, who produced the most publications, had a great influence on this research. The focus in this field was clarified by analyzing the top 10 citations and co-citations publications. Moreover, the analysis of the keywords showed Important topics: "Classification of pancreatic tumor disease" "Development of EUS in the diagnosis of pancreatic tumor diseases," and "Development of EUS in the treatment of pancreatic tumor diseases."

Conclusion

For the first time, bibliometric analysis was used to gain a deep understanding of the global trends of studies investigating EUS in pancreatic tumor diseases. The EUS field is rapidly evolving, and our study may be a critical reference for clinical researchers related to this field.

Endoscopic ultrasound role in pancreatic adenocarcinoma treatment: A review focusing on technical success, safety and efficacy

The impressive technological advances in recent years have rapidly translated into the shift of endoscopic ultrasound (EUS) from diagnostic modality into an interventional and therapeutic tool. Despite the great advance in its diagnosis, the majority of pancreatic adenocarcinoma cases are inoperable when diagnosed, thus demanding alternative optional therapies. EUS has emerged as an easy, minimally invasive modality targeting this carcinoma with different interventions that have been reported recently. In this review we summarize the evolving role of interventional therapeutic EUS in pancreatic adenocarcinoma management.

Role of therapeutic endoscopic ultrasound in gastrointestinal malignancy- current evidence and future directions

Endoscopic ultrasound (EUS) has come a long way from a mere diagnostic tool to an advanced therapeutic modality. With the advent of better technologies and accessories, EUS has found ground in the management of gastrointestinal (GI) malignancies, not only for diagnosis but also for therapeutic purposes. EUS can tackle a host of conditions, including hepato-pancreatico-biliary malignancies. Advances and experience in various EUS-guided biliary drainage techniques have enabled the endosonologist to tackle biliary obstruction when conventional techniques of endoscopic retrograde cholangiopancreatography (ERCP) and/or percutaneous transhepatic biliary drainage (PTBD) fails. More and more emerging data not only establishes the safety of EUS-BD but also demonstrates superior efficacy over PTBD and sometimes even ERCP. Malignant gastric outlet obstruction can now be safely managed with EUS-guided gastroenterostomy. Starting from pain management in malignant tumors through celiac plexus neurolysis to various tumor ablative therapies, EUS has forged ahead over percutaneous treatment or surgical options in the management of GI malignancies. Additional data is now coming up on the prospects of EUS-guided immunotherapy and biological therapy for tumor management. The future of EUS therapeutics in the field of GI malignancies is bright. With increasing evidence, this modality becoming a key player in management of a host of complex clinical conditions arising out of GI malignancies is in the offing. This review focuses on elucidating the role of therapeutic EUS in the management of GI malignancies, a synopsis of various techniques, data on its safety and efficacy as well as future advancements in this domain.

Endoscopic ultrasound-guided therapies for pancreatic solid tumors: An overview

The close proximity of the endoscopic ultrasound (EUS) probe to the pancreas, coupled with the ease with which a needle can be inserted into a pancreatic lesion, have contributed to the development of EUS-guided therapies for both adenocarcinoma and neuroendocrine pancreatic neoplasms. EUS-guided fine needle injection of different types of drugs, implantation of fiducial markers to facilitate stereotactic body radiation therapy or of radioactive seeds to perform brachytherapy, and the use of different thermal and nonthermal ablation devices and techniques have all been tested in preliminary human studies. This manuscript will present the available evidence accumulated thus far in the field of EUS-guided oncological treatment of pancreatic solid tumors, along with a look into possible future applications.

Endoscopic Management of Pancreatobiliary Neoplasms

Endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) are the mainstays of interventional endoscopic practice. EUS occupies a central role in the diagnosis of pancreatobiliary neoplasms and offers a platform for a wide range of direct tumor therapies. Initial steps have demonstrated the feasibility of such applications in animal models and pilot studies. Larger clinical trials and incorporation of EUS-based therapies into cooperative cancer studies might demonstrate an impact in the clinical prognosis of patients with pancreatic cancer. ERCP plays an important role in elucidating indeterminate biliary strictures and in treating patients with malignant biliary obstruction who are symptomatic or have borderline-resectable or unresectable disease. ERCP-directed ablative therapies enable neoadjuvant and palliative intervention in patients with malignant biliary obstruction, in particular perihilar cholangiocarcinoma. Additional comparative, multicenter studies are needed to better understand the safety and efficacy of endobiliary brachytherapy, photodynamic therapy, and radiofrequency ablation in patients with pancreatobiliary malignancies.

Recent Advances in Therapeutic Endosonography for Cancer Treatment

Therapeutic endosonography (EUS) may play an important role in the management of cancers. EUS-guided fiducial placement has a high success rate and can aid in stereotactic radiotherapy. EUS-guided tumor ablation therapies can help in palliation of locally advanced tumors. EUS-guided antitumor injection seems to be feasible and safe in animals; initial human studies suffer from small sample size and lack of controls. Randomized, controlled trials have not shown benefit over conventional therapy. EUS celiac plexus neurolysis has gained popularity and is performed by interventional endosonographers. Large trials are needed to determine the most appropriate indications and overall usefulness of these therapies.

Endoscopic ultrasonography-guided tumor ablation

Real-time guidance of needle advancement has transformed endoscopic ultrasound (EUS) from a diagnostic to an interventional procedure. EUS-guided fine-needle puncture has application in various interventional procedures (drainage of pseudocyst, biliary intervention, and injection of drugs). Celiac plexus or ganglion neurolysis for pain control is the major current EUS-guided fine-needle injection procedure. Feasibility and safety to accurately position needle devices and/or inject under real-time EUS imaging with precise delivery of interventional agent have expanded the use of EUS to ablate tumors. These include radiofrequency ablation, or delivery of fiducial markers, potential antitumor agents, or radioactive seeds, in the cancer mass. Minimally invasive EUS-guided antitumor therapy is primarily used for pancreatic cancer because of better anatomic access (vs other imaging modality) and the dismal prognosis (despite improvements in surgery and chemoradiation). Also, the response to parenteral chemotherapy in pancreatic cancer is poor because of suboptimal drug delivery resulting from hypovascularity and abundant desmoplasia. Other targets for EUS-guided tumor ablation are pancreatic neuroendocrine tumor and pancreatic cyst lesion, which are less aggressive and curable by resection. However, patients non-eligible for surgery may benefit from local EUS-guided ablation.

Injectable polypeptide micelles that form radiation crosslinked hydrogels in situ for intratumoral radiotherapy

Intratumoral radiation therapy - 'brachytherapy' - is a highly effective treatment for solid tumors, particularly prostate cancer. Current titanium seed implants, however, are permanent and are limited in clinical application to indolent malignancies of low- to intermediate-risk. Attempts to develop polymeric alternatives, however, have been plagued by poor retention and off-target toxicity due to degradation. Herein, we report on a new approach whereby thermally sensitive micelles composed of an elastin-like polypeptide (ELP) are labeled with the radionuclide (131)I to form an in situ hydrogel that is stabilized by two independent mechanisms: first, body heat triggers the radioactive ELP micelles to rapidly phase transition into an insoluble, viscous coacervate in under 2 min; second, the high energy β-emissions of (131)I further stabilize the depot by introducing crosslinks within the ELP depot over 24h. These injectable brachytherapy hydrogels were used to treat two aggressive orthotopic tumor models in athymic nude mice: a human PC-3 M-luc-C6 prostate tumor and a human BxPc3-luc2 pancreatic tumor model. The ELP depots retained greater than 52% and 70% of their radioactivity through 60 days in the prostate and pancreatic tumors with no appreciable radioactive accumulation (≤ 0.1% ID) in off-target tissues after 72h. The (131)I-ELP depots achieved >95% tumor regression in the prostate tumors (n=8); with a median survival of more than 60 days compared to 12 days for control mice. For the pancreatic tumors, ELP brachytherapy (n=6) induced significant growth inhibition (p=0.001, ANOVA) and enhanced median survival to 27 days over controls.

[Endoscopic Ultrasound-guided Local Therapy of Pancreatic Tumors]

The development of curvilinear EUS has enabled EUS-guided fine-needle aspiration of intra-abdominal mass lesions. With the introduction of interventional EUS, this technology has undergone several modifications in order to be applied to clinical medicine. One of the potential uses of interventional EUS is the EUS-guided local therapy of pancreatic tumors. Various treatment modalities such as fine-needle injection, radiofrequency ablation, photodynamic therapy, laser ablation, and brachytherapy have been tried under EUS guidance. Some of these modalities are being applied clinically. These methods for EUS-guided local therapy of pancreatic tumors will be reviewed in this article.

Endoscopic ultrasound-guided therapies in pancreatic neoplasms

Endoscopic ultrasound (EUS) has evolved from being primarily a diagnostic modality into an interventional endoscopic tool for the management of both benign and malignant gastrointestinal illnesses. EUS-guided therapy has garnered particular interest as a minimally invasive approach for the treatment of pancreatic cancer, a disease often complicated by its aggressive course and poor survival. The potential advantage of an EUS-guided approach revolves around real-time imaging for targeted therapy of a difficult to reach organ. In this review, we focus on EUS-guided therapies for pancreatic neoplasms.

The role of endoscopic ultrasound in the radiation treatment of pancreatic tumor

Radiotherapy is an established treatment modality for patients with pancreatic cancer. Image-guided radiation therapy (IGRT) allows the delivery of high doses to the tumour, while sparing the sensitive tissues around it, thus reducing side effects. However, the need of precisely contouring and identifying the target lesion is mandatory to be able to perform IGRT. Endoscopic ultrasound has been progressively implemented in the field of radiotherapy as a tool for intra-lesional placement of fiducial markers to perform IGRT and for direct placing of sealed radioactive sources in contact with the target lesions. In the current paper we provide an updated review on the role of endoscopic ultrasound in the radiation treatment of pancreatic cancer, highlighting areas of future research.

Endoscopic ultrasound in gastroenterology: From diagnosis to therapeutic implications

Since its advent in 1980, the scope of endoscopic ultrasound (EUS) has grown to include a wide range of indications, and it is now being incorporated as an integral part of everyday practice in the field of gastroenterology. Its use is extending from an adjuvant imaging aid to utilization as a therapeutic tool for various gastrointestinal disorders. EUS was first used to visualize remote organs, such as the pancreas and abdominal lymph nodes. When fine needle aspiration was introduced, the indications for EUS expanded to include tissue sampling for diagnostic purposes. At the same time, the needle can be used to convey a potential therapy to the internal organs, allowing access to remote sites. In this review, we aim to highlight the expanding spectrum of EUS indications and uses in the field of gastroenterology.

Pilot trial of endoscopic ultrasound-guided interstitial chemoradiation of UICC-T4 pancreatic cancer

Background and aims:

Both interstitial brachytherapy and interstitial chemotherapy are effective in improving local control in patients with local UICC-T4 pancreatic cancer. In this study, we report the results of endoscopic ultrasound (EUS)-guided interstitial chemoradiation (EUS-ICR) in patients with advanced pancreatic cancer, with respect to tumor response, clinical response, safety, and complications.

Patients and methods:

A total of 8 patients (3 men, 5 women; median age of 69) with T4 pancreatic adenocarcinoma were the subjects of this study. A mean of 18 radioactive seeds and 36 intratumoral implants for sustained delivery of 5-fluorouracil in each patient were implanted into the tumors using EUS-guided needle puncture. The mean total implanted radioactive activity was 13.68 mCi, the mean total dose of intratumoral 5-fluorouracil was 3.6 g, and the mean volume of implants was 28 cm³. The conditions of the patients were followed-up by examination and imaging tests every two months. Clinical endpoints included the Karnofsky performance status, pain response, tumor response (assessed by computed tomography and/or EUS), and survival.

Results:

During a median follow-up period of 8.3 months, the objective tumor response was classified as “partial” in 1 of 8 patients (with a median duration of partial response of 3 months), “minimal” in 2 patients, and indicative of “stable disease”, in 3 of 8 patients. Clinical benefit was shown in 4 of 8 patients, which was mostly due to pain reduction, and lasted for 3.5 months. No local complications or hematologic toxicity occurred.

Conclusions:

EUS-ICR had a moderate local anti-tumor effect, showed some clinical benefits in 4 of the 8 patients, and was well tolerated by all the patients in this study.

Interventional endoscopic ultrasonography

OPINION STATEMENT

Endoscopic ultrasound (EUS) is not only a diagnostic tool but also an interventional and therapeutic procedure. Indeed, in addition to tissue acquisition, it can also drain fluid collections adjacent to the gastrointestinal tract, provide access to biliary and pancreatic ducts, biliary, pancreatic, and gallbladder drainage, pancreatic cyst ablation, and, finally, provide anti-tumoral treatments and interventional vascular procedures. Although several improvements have been made in the last decade, the full potential of interventional EUS is yet to be completely explored. Future areas of research are the development of dedicated tools and accessories, the standardization of the interventional procedures, and the widening of the use of EUS, while increasing the expertise worldwide. In addition, more data, based on well-performed, possibly randomized clinical trials, are needed to accurately determine the risks and long-term outcomes of these interventions. We firmly believe that interventional EUS can play a pivotal role in anti-tumor treatments, by the fine-needle injection of anti-tumoral agents, tumor ablation, and assisting radiation treatment with gold fiducial placement and the implantation of intralesional seeds. The goal of the near future will be to offer targeted therapy and monitoring of tumor treatment response in a more biologically driven manner than has been available in the past. Interventional EUS will be an essential part of the multidisciplinary approach to cancer treatment.

Role of endoscopic ultrasound in treatment of pancreatic cancer

Endoscopic ultrasound (EUS) can help diagnose diseases with high accuracy because it overcomes the limitations of gastrointestinal gas and abdominal fat. The emergence of curved linear-array echoendoscopy has significantly promoted the applications of the technique to new levels. The advancement has appeared from EUS imaging to EUS-guided fine needle aspiration, drainage and injection. Computed tomography and magnetic resonance imaging present certain limitations for diagnosing pancreatic tumors due to the specificity of the location of such growths. In addition, traditional chemotherapy does not show ideal results because pancreatic cancer (PC) exhibits hypovascular characteristics. Interventional EUS can overcome these limitations and has potential to become the mainstream method of PC local treatment in the future. This paper reviews the use of interventional EUS in the treatment of PC based on previous studies.

Endoscopic ultrasound and fine needle aspiration in pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer mortality for both men and women in the United States. Overall 5-year survival from time of diagnosis is less than 5%. The only meaningful chance for cure results from early detection while the tumor remains resectable without locoregional extension or metastasis. Endoscopic ultrasound (EUS) is uniquely suited to the examination and treatment of the pancreas. Endoscopic ultrasound can provide important information with regard to disease stage including involvement of the mesenteric vasculature, adjacent organ invasion, and regional lymph node metastasis. In addition, EUS is considered the procedure of choice for tissue diagnosis of pancreatic cancer. More recently, EUS has developed therapeutic roles in an array of other clinical situations including EUS-guided fine needle injection, EUS-guided biliary drainage, celiac plexus neurolysis, brachytherapy, fiducial placement, and emerging antitumor agents delivered directly into the tumor.

Endoscopic ultrasound-guided oncologic therapy for pancreatic cancer

Since the development of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) in the early 1990s, its application has been extended to various diseases. For pancreatic cancer, EUS-FNA can obtain specimens from the tumor itself with fewer complications than other methods. Interventional EUS enables various therapeutic options: local ablation, brachytherapy, placement of fiducial markers for radiotherapy, and direct injection of antitumor agents into cancer. This paper will focus on EUS-guided oncologic therapy for pancreatic cancer.

Endoscopic ultrasound-guided fiducial markers and brachytherapy

Endoscopic ultrasound (EUS)-guided needle placement of small radiopaque particles paves the way for EUS-guided fiducial markers and brachytherapy. Stereotactic body radiation therapy relies on image-guided radiation therapy (IGRT), permitting escalation of radiation dose to tumors while minimizing dose to normal tissues. Fiducial markers are radiopaque spheres, coils, or seeds that are implanted in or near tumors for IGRT. Brachytherapy is a therapeutic modality for various cancers. Both require precise and minimally-invasive seed placement, which EUS provides. This article reviews recent literature regarding the safety and efficacy of these procedures and discusses novel concepts, including EUS-guided celiac ganglia radiation neurolysis.

Endoscopic ultrasound-guided antitumor agents

The development of linear-array endoscopic ultrasonography (EUS), with its real-time guidance of needle advancement, changed EUS from a diagnostic procedure to an interventional procedure. EUS-guided fine-needle injection (EUS-FNI) is an attractive minimally invasive delivery system with potential applications in local (intratumoral) and combination therapy against esophageal and pancreatic cancers. The evidence of the feasibility of EUS-FNI of antitumor agents has been expanding with promising results.

Endoscopic palliation of pancreatic cancer

There is no doubt that our long-range goal is to cure pancreatic cancer. Realistically, most of what we can do currently is treat the disabling symptoms of this dreadful disease. Biliary decompression, intestinal stenting, celiac plexus neurolysis, and fiducial placement are some of the endoscopic procedures that aim to provide better quality of life to patients suffering from this disease. A thorough understanding of these options will help patients make good decisions in choosing the proper treatment. Endoscopists who perform these procedures must possess great skills, but importantly, they must also be compassionate and act with good judgment.

Endoscopic ultrasound-guided fine needle injection for cancer therapy: the evolving role of therapeutic endoscopic ultrasound

Endoscopic ultrasound (EUS) is central to the diagnosis and staging of many malignancies, but now has an evolving role in cancer therapy. EUS-guided fine needle injection (FNI) is already used for palliative interventions such as treatment of pain through nerve blockade and to guide biliary decompression when conventional ERCP is not possible. More recently, EUS-FNI has been used to deliver specific anti-tumor agents for pancreatic cyst ablation and local control of tumor growth in patients with unresectable solid malignancies. The agents used to date include ethanol, brachytherapy seeds, and chemotherapeutic agents such as paclitaxel. In addition, FNI of new immunomodulating cell cultures such as mixed lymphocyte and dendritic cell cultures has also been reported, as has FNI of several different viral vectors for antitumor therapy. Although experience with these agents remains preliminary, EUS-FNI is a minimally invasive approach to deliver local antitumor agents, and is likely to have an expanding role in cancer therapy.

Interventional endoscopic ultrasonography: present and future

The technical advances in endoscopic ultrasonograpy (EUS) and accessories have enabled performing EUS-guided intervention in the pancreas and biliary tract. Many research centers have been performing or investigating EUS-guided drainage, EUS-guided celiac plexus neurolysis and block, EUS-guided anastomosis that includes choledocho-enterostomy and choledocho-gastrostomy, EUS-guided ablation and injection therapy mainly for pancreatic neoplasm, EUS-guided photodynamic therapy and EUS-guided brachytherapy. Some of these are currently clinical applications and others are under investigations in clinical studies or animal models. Further detailed randomized controlled clinical trials and the development of materials will bring us into a new era of therapeutic EUS.

Interventional endoscopic ultrasonography: present and future

The technical advances in endoscopic ultrasonograpy (EUS) and accessories have enabled performing EUS-guided intervention in the pancreas and biliary tract. Many research centers have been performing or investigating EUS-guided drainage, EUS-guided celiac plexus neurolysis and block, EUS-guided anastomosis that includes choledocho-enterostomy and choledocho-gastrostomy, EUS-guided ablation and injection therapy mainly for pancreatic neoplasm, EUS-guided photodynamic therapy and EUS-guided brachytherapy. Some of these are currently clinical applications and others are under investigations in clinical studies or animal models. Further detailed randomized controlled clinical trials and the development of materials will bring us into a new era of therapeutic EUS.

Feasibility of EUS-guided injection of irinotecan-loaded microspheres into the swine pancreas

BACKGROUND

LC beads (Biocompatibles International plc) are designed for the time-released delivery of the chemotherapeutic agent irinotecan into focal, hypervascularized, hepatic tumors.

OBJECTIVE

To determine the feasibility of EUS-guided injection of LC beads (with/without irinotecan) into the swine pancreas.

DESIGN

Survival animal study.

SETTING

Academic center.

SUBJECTS

This study involved 12 Yorkshire swine.

INTERVENTION

LC beads without irinotecan and loaded with up to 300 mg of irinotecan were injected under EUS guidance with a 19-gauge needle into the tail of the pancreas. CT scanning and necropsy with histology were performed at day 7.

MAIN OUTCOME MEASUREMENTS

Feasibility of the injections, gross and microscopic evidence of pancreatic inflammation, and clinical tolerance by the animals.

RESULTS

After injection of LC beads with/without irinotecan, in 10 of 12 animals an intrapancreatic, hyperechoic focus with an average diameter of 2.2 cm was visible by EUS, and a hypodense area in the tail of the pancreas was visible by contrast CT. In 2 animals (1 with irinotecan and 1 without) no beads were seen on CT. In 10 of 12 animals, a depot of beads was located in the tail of the pancreas on gross inspection and histology. Drug depot with only localized pancreatic tissue reactions was seen on histopathologic review.

LIMITATIONS

Animal study.

CONCLUSION

The EUS-guided injection of LC beads (with/without irinotecan) into the pancreas of the pig is feasible and safe. This technique is a potential minimally invasive local treatment option for locally advanced pancreatic cancer.

Endoscope-assisted brachytherapy for pancreatic cancer: From tumor killing to pain relief and drainage

Locally advanced or metastatic pancreatic cancer has been a long-term challenge to clinicians, due to the poor overall survival rate compared with that of other gastrointestinal malignancies. Recently, with the emerging applications of therapeutic endoscopic ultrasonography (EUS), EUS- guided fine needle injection with antitumor agents is considered a promising modality. In this review, we summarize recently published data on the efficacy of endoscope guided interventional procedures with radioactive seeds. Firstly, EUS-guided iodine-125 seed implantation was reported to have a short-term efficacy on pancreatic cancer, with a three-month partial remission rate of 13.6% to 27%. Thereafter, feasibility of celiac ganglion radiation was tested in animal models to achieve pain relief. Recently, a seed-based stent has been introduced in the endoscopic retrograde cholangio-pancreatography (ERCP) drainage of biliary obstruction caused by pancreatic cancer, with a response rate of 72.7%. In addition, we discuss the potential of radioactive seed-based, endoscope-assisted interventional treatment of patients with locally advanced pancreatic cancer. Further studies should focus on the precise amount and distribution of seeds with the aim to improve the survival rate as well as the quality of life.

Endoscopic ultrasonography-guided ablation therapy

Endoscopic ultrasonography (EUS) imaging has undergone extensive technological advancement since its development in the 1980s, including improvement of echoendoscopes with larger channels and accessories.These advancements enable not only tissue procurement for diagnosis but also therapeutic interventions that hitherto would have required surgery, with its attendant risks. A wide array of interventional procedures are performed under EUS guidance, including celiac plexus neurolysis, drainage of pancreatic and pelvic fluid collections, drainage of obstructive pancreatic-biliary ducts, ablation of cyst neoplasms in the pancreas, and implantation of fiducial markers and radioactive seeds into gastrointestinal tumors. Various experimental procedures are also underway to evaluate the role of EUS in radiofrequency ablation, vascular therapy, and natural orifice transluminal endoscopic surgery. In this review, we examine the various EUS-guided ablation therapies currently undertaken in humans.

Interventional endoscopic ultrasonography: applications for cancer related treatment

For tissue diagnosis in patients with abnormalities of various organs, endoscopic ultrasonography (EUS)-guided fine needle aspiration (EUS-FNA) has emerged as an effective technique. Subsequently, EUS-guided fine needle injection (EUS-FNI) has expanded the clinical utility of EUS. Several applications of EUS-FNI for anti-cancer efforts have included celiac nerve blocking and drug delivery into tumors, such as ablation, chemotherapy, gene therapy, and cytoimplantation. Furthermore, chemosensitivity tests with materials obtained using EUS-FNA are available to produce tailor-made medicines. Demonstrably, EUS-guided intervention has opened new and exciting clinical applications for the management of malignancies.

Interventional endoscopic ultrasonography

Endoscopic ultrasonography (EUS) is the combination of endoscopy and intraluminal ultrasonography. This allows use of a high frequency transducer, which, due to the short distance to the target lesion, enables ultrasonographic images of high resolution to be obtained. Endoscopic ultrasonography is now a widely accepted modality for the diagnosis of pancreatobiliary diseases. It can be used to determine the depth of invasion of gastrointestinal malignancies, and often for visualizing lesions more precisely than other imaging modalities. The most important early limitation of EUS was the lack of specificity in the differentiation between benign and malignant changes. In 1992, EUS-guided fine needle aspiration (EUS-FNA) of lesions in the pancreas head has been made possible using a curved linear array echoendoscope. Since then, many researchers have expanded the indication of EUS-FNA to various kinds of lesions and also for a variety of therapeutic purposes. In this review, we particularly focus on the present and future roles of interventional EUS, including EUS-FNA and therapeutic EUS.

Endoscopic ultrasound: moving from diagnostics to therapeutics

Endoscopic ultrasound was initially introduced in the 1980s as a diagnostic modality using echoendoscopes with radial scanning that permitted reconstruction of cross-sectional images similar to computed tomography The close proximity of the ultrasound transducer to the gastrointestinal wall and retroperitoneal structures allowed a detailed examination that is not possible with cross-sectional imaging such as computed tomography and magnetic resonance imaging. It proved to be highly accurate and useful in the staging of gastrointestinal malignancies, as well as in characterizing the nature of subepithelial lesions and disorders of the pancreaticobiliary system. The introduction of linear echoendoscopes facilitated fine needle aspiration because, with linear scanning, it was able to trace the path of the tip of the needle during the puncture process. In addition to being very useful for tissue acquisition for diagnostic purposes, the principles behind endoscopic ultrasound-guided fine needle aspiration paved the way for the development of therapeutic endoscopic ultrasound. Substances could now be delivered by endoscopic ultrasound into targeted areas, an example being an endoscopic ultrasound-guided celiac plexus block and neurolysis. In addition, the endoscopic ultrasound-guided puncture of fluid collections, abscesses and obstructed biliary and pancreatic ductal systems facilitated the passage of guidewires, thus allowing therapeutic drainage procedures to be performed using the Seldinger technique. This review summarizes the diagnostic capability of endoscopic ultrasound and then moves on to elaborate in detail its therapeutic capability and potential.

EUS-guided photodynamic therapy with verteporfin for ablation of normal pancreatic tissue: a pilot study in a porcine model (with video)

BACKGROUND

EUS-guided photodynamic therapy (PDT) with the photosensitizing agent porfimer sodium has been shown to be effective in ablation of pancreatic tissue.

OBJECTIVE

The objective of this study was to determine the effectiveness and safety of EUS PDT with verteporfin, a photosensitizer associated with less photosensitivity.

DESIGN

Prospective investigation of 6 swine that received an IV injection of 6 mg/m2 of verteporfin before EUS.

SETTING

Hospital animal laboratory.

INTERVENTIONS

The tail of the pancreas was located with EUS and was used to guide the placement of a light catheter. The pancreatic tail was exposed to 10, 15, or 20 minutes of laser light (689 nm).

MAIN OUTCOME MEASUREMENTS

Follow-up abdominal CT, liver and renal function tests, and serum pancreatic enzymes levels were performed. Histology of the pancreas was obtained 7 days after the procedure on necropsy.

RESULTS

Localized tissue necrosis within the pancreatic tail (range 6.6-30.5 mm in diameter) was seen in all animals. The diameter of the necrotic tissue was directly related to the dose of light. No post-procedural complications were observed.

LIMITATIONS

Normal animal model (lack of malignant tissue).

CONCLUSIONS

EUS-guided PDT of porcine pancreas with verteporfin achieved localized pancreatic tissue ablation in a dose-related fashion.

Ultrasonography of the pancreas. 6. Endoscopic imaging

EUS is a high-resolution technique for pancreatic imaging. EUS has applictions in detecting and staging pancreatic tumors, EUS guided FNA of the pancreas for tissue diagnosis, and evaluation of chronic pancreatitis as well as EUS guided therapy such as celiac plexus block. This is a review of EUS imaging (EUS) of the pancreas covering technical aspects, clinical indications, advantages, and pitfalls as well as emerging trends in the field.