Percutaneous cecostomy: 25-year two institution experience.

BACKGROUND: Reports of technical success, adverse events, and long-term outcome of percutaneous cecostomy in children are limited. OBJECTIVE: To characterize technical success, 30-day severe adverse events, and long-term outcome of percutaneous cecostomy at two centers. MATERIALS AND METHODS: A retrospective review of hospital course and long-term follow-up (through May 2022) of percutaneous cecostomy tubes placed May 1997 to August 2011 at two children's hospitals was used. Outcomes assessed included technical success (defined as successful tube placement into the colon allowing antegrade colonic enemas), length of stay, 30-day severe adverse events, surgery consults, surgical repair, VP shunt infection, ongoing flushes, tube removal, duration between maintenance tube exchanges, and deaths. RESULTS: A total of 215 procedures were performed in 208 patients (90 institution A, 125 institution B). Tubes were placed for neurogenic bowel (72.1%, n = 155) and functional constipation (27.9%, n = 60). Technical success was 98.1% (211/215) and did not differ between centers (p = 0.74). Surgical repair was required for bowel leakage in 5.1% (11/215) and VP shunt infection was managed in 2.1% (2/95). Compared to functional constipation, patients with neurogenic bowel had higher % tube remaining (65.3% [96/147] versus 25.9% [15/58], p < 0.001) and higher ongoing flushes at follow-up (42.2% [62/147] versus 12.1% [7/58], p < 0.001). Tube removal for dissatisfaction occurred in 15.6% [32/205] and did not differ between groups (p = 0.98). Eight deaths due to co-morbidity occurred after a median of 7.4 years (IQR 9.3) of tube access. CONCLUSION: Percutaneous cecostomy is technically successful in the vast majority of patients and provided durable access in most. Bowel leakage and VP shunt infection are uncommon, severe adverse events.

Generation of Terawatt Attosecond Pulses from Relativistic Transition Radiation.

When a femtosecond duration and hundreds of kiloampere peak current electron beam traverses the vacuum and high-density plasma interface, a new process, that we call relativistic transition radiation (RTR), generates an intense ∼100 as pulse containing ∼1 terawatt power of coherent vacuum ultraviolet (VUV) radiation accompanied by several smaller femtosecond duration satellite pulses. This pulse inherits the radial polarization of the incident beam field and has a ring intensity distribution. This RTR is emitted when the beam density is comparable to the plasma density and the spot size much larger than the plasma skin depth. Physically, it arises from the return current or backward relativistic motion of electrons starting just inside the plasma that Doppler up shifts the emitted photons. The number of RTR pulses is determined by the number of groups of plasma electrons that originate at different depths within the first plasma wake period and emit coherently before phase mixing.

Suppression of Deflecting Forces in Planar-Symmetric Dielectric Wakefield Accelerating Structures with Elliptical Bunches.

Wakefield based accelerators capable of accelerating gradients 2 orders of magnitude higher than present accelerators offer a path to compact high energy physics instruments and light sources. However, for high gradient accelerators, beam instabilities driven by commensurately high transverse wakefields limit beam quality. Previously, it has been theoretically shown that transverse wakefields can be reduced by elliptically shaping the transverse sizes of beams in dielectric structures with planar symmetry. Here, we report experimental measurements that demonstrate reduced transverse wakefields for elliptical beams in planar symmetric structures which are consistent with theoretical models. These results may enable the design of gigavolt-per-meter gradient wakefield based accelerators that produce and stably accelerate high quality beams.

Follistatin Gene Therapy for Sporadic Inclusion Body Myositis Improves Functional Outcomes.

Sporadic inclusion body myositis, a variant of inflammatory myopathy, has features distinct from polymyositis/dermatomyositis. The disease affects men more than women, most commonly after age 50. Clinical features include weakness of the quadriceps, finger flexors, ankle dorsiflexors, and dysphagia. The distribution of weakness is similar to Becker muscular dystrophy, where we previously reported improvement following intramuscular injection of an isoform of follistatin (FS344) by AAV1. For this clinical trial, rAAV1.CMV.huFS344, 6 × 1011 vg/kg, was delivered to the quadriceps muscles of both legs of six sporadic inclusion body myositis subjects. The primary outcome for this trial was distance traveled for the 6-min walk test. The protocol included an exercise regimen for each participant. Performance, annualized to a median 1-year change, improved +56.0 m/year for treated subjects compared to a decline of -25.8 m/year (p = 0.01) in untreated subjects (n = 8), matched for age, gender, and baseline measures. Four of the six treated subjects showed increases ranging from 58-153 m, whereas two were minimally improved (5-23 m). Treatment effects included decreased fibrosis and improved regeneration. These findings show promise for follistatin gene therapy for mild to moderately affected, ambulatory sporadic inclusion body myositis patients. More advanced disease with discernible muscle loss poses challenges.

Image-guided percutaneous removal of ballistic foreign bodies secondary to air gun injuries.

BACKGROUND: Ballistic injuries with retained foreign bodies from air guns is a relatively common problem, particularly in children and adolescents. If not removed in a timely fashion, the foreign bodies can result in complications, including pain and infection. Diagnostic methods to identify the presence of the foreign body run the entire gamut of radiology, particularly radiography, ultrasound (US) and computed tomography (CT). Removal of the foreign bodies can be performed by primary care, emergency, surgical, and radiologic clinicians, with or without imaging guidance. OBJECTIVE: To evaluate the modalities of radiologic detection and the experience of image-guided ballistic foreign body removal related to air gun injuries within the interventional radiology department of a large pediatric hospital. MATERIALS AND METHODS: A database of more than 1,000 foreign bodies that were removed with imaging guidance by the interventional radiologists at our institution was searched for ballistic foreign bodies from air guns. The location, dimensions, diagnostic modality, duration, complications and imaging modality used for removal were recorded. In addition, the use of sedation and anesthesia required for the procedures was also recorded. RESULTS: Sixty-one patients with ballistic foreign bodies were identified. All foreign bodies were metallic BBs or pellets. The age of the patients ranged from 5 to 20 years. The initial diagnostic modality to detect the foreign bodies was primarily radiography. The primary modality to assist in removal was US, closely followed by fluoroscopy. For the procedure, 32.7% of the patients required some level of sedation. Only two patients had an active infection at the time of the removal. The foreign bodies were primarily in the soft tissues; however, successful removal was also performed from intraosseous, intraglandular and intratendinous locations. All cases resulted in successful removal without complications. CONCLUSION: Image-guided removal of ballistic foreign bodies secondary to air guns is a very effective procedure that can obviate the need for open surgical procedures in children.

Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields.

Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of less than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. The underlying physics that leads to the lower than expected emittance growth is elucidated.

A phase 1/2a follistatin gene therapy trial for becker muscular dystrophy.

Becker muscular dystrophy (BMD) is a variant of dystrophin deficiency resulting from DMD gene mutations. Phenotype is variable with loss of ambulation in late teenage or late mid-life years. There is currently no treatment for this condition. In this BMD proof-of-principle clinical trial, a potent myostatin antagonist, follistatin (FS), was used to inhibit the myostatin pathway. Extensive preclinical studies, using adeno-associated virus (AAV) to deliver follistatin, demonstrated an increase in strength. For this trial, we used the alternatively spliced FS344 to avoid potential binding to off target sites. AAV1.CMV.FS344 was delivered to six BMD patients by direct bilateral intramuscular quadriceps injections. Cohort 1 included three subjects receiving 3 × 10(11) vg/kg/leg. The distance walked on the 6MWT was the primary outcome measure. Patients 01 and 02 improved 58 meters (m) and 125 m, respectively. Patient 03 showed no change. In Cohort 2, Patients 05 and 06 received 6 × 10(11) vg/kg/leg with improved 6MWT by 108 m and 29 m, whereas, Patient 04 showed no improvement. No adverse effects were encountered. Histological changes corroborated benefit showing reduced endomysial fibrosis, reduced central nucleation, more normal fiber size distribution with muscle hypertrophy, especially at high dose. The results are encouraging for treatment of dystrophin-deficient muscle diseases.

A comparison of pediatric gastrostomy tube placement techniques.

PURPOSE: This study aimed to compare different techniques for placement of gastrostomy tubes in a pediatric population. STUDY DESIGN: A retrospective review was performed for patients less than 18 years of age who underwent gastrostomy tube placement at a single academic children's hospital between 2010 and 2012. Techniques for gastrostomy placement included Open Stamm, percutaneous endoscopic gastrostomy (PEG), fluoroscopy guided, laparoscopic, and laparoscopic assisted PEG. Pre-operative characteristics of patients and post-operative outcomes were compared between techniques. RESULTS: Most patients underwent an Open Stamm (43 %) or PEG (39 %). There were significant differences between groups with respect to primary diagnoses, prior surgeries, and ASA classification. Major complications were rare, with less than 3 % requiring reoperation within 30 days; however, minor complications and returns to the emergency department were common. Unintentional tube dislodgements occurred in 22 % of all patients, with Open Stamm technique identified as an independent predictor of unintentional dislodgement (p < 0.0001). CONCLUSIONS: Although conclusions from this retrospective analysis are limited due to heterogeneity between groups, open Stamm gastrostomy placement in children was associated with increased negative outcomes including unintentional tube dislodgements, returns to the emergency department, and need for reoperation within 30 days. Prospective analysis of the various techniques is needed to confirm that minimally invasive techniques for gastrostomy tube placement are associated with a less complicated post-operative course.

Development of a pediatric-specific clinical probability tool for diagnosis of venous thromboembolism: a feasibility study.

BACKGROUND: Pediatric venous thromboembolism (VTE) is an increasingly common, difficult to diagnose problem. Clinical probability tools (CPT) for adults estimate VTE likelihood, but are not available for children. We hypothesized that a pediatric-specific CPT is feasible. METHODS: Radiology reports were utilized to identify children imaged for suspected VTE. Relevant signs, symptoms, and comorbidity variables, identified from published literature, were extracted from corresponding medical records. Variables associated with pediatric VTE were incorporated into a multivariate logistic regression to create a pilot CPT which was confirmed on a separate cohort. RESULTS: A total of 389 subjects meeting inclusion criteria were identified: 91 with VTE and 298 without. Univariate analysis revealed male gender (odds ratio (OR) = 2.96; P < 0.001), asymmetric extremity (OR = 1.76; P = 0.033), central venous catheter utilization and/or dysfunction (OR = 2.51; P < 0.001), and cancer (OR = 2.35; P = 0.014) as VTE predictive variables. Documentation of an alternate diagnosis was inversely related to VTE (OR = 0.42; P = 0.004). Receiver operating characteristic analysis of the derived CPT demonstrated reasonable ability to discriminate VTE probability in the training cohort (area under the curve (AUC) = 0.73; P < 0.001) and moderate discrimination in a separate validation cohort of 149 children (AUC = 0.64; P = 0.011). CONCLUSION: A pediatric-specific VTE CPT is feasible, would facilitate early diagnosis, and could lead to improved outcomes.

Percutaneous transcervical thoracic duct embolization for treatment of a cervical lymphocele following anterior spinal fusion: a case report.

Thoracic duct injury is an uncommon complication of neck dissection and cervical spinal surgery that is associated with significant morbidity. The authors describe an unusual case of thoracic duct injury during anterior spinal fusion resulting in a large prevertebral lymphocele presenting with dysphagia, respiratory distress, and chyloptysis. Surgical closure of the lymphocele was unsuccessful, and percutaneous drainage and sclerotherapy was performed. A large thoracic duct branch communicating with the lymphocele became evident during sclerotherapy, and embolization of the duct was performed via a percutaneous transcervical approach. Symptoms immediately resolved, and the patient remained asymptomatic at 6-month follow-up.

Energy doubling of 42 GeV electrons in a metre-scale plasma wakefield accelerator.

The energy frontier of particle physics is several trillion electron volts, but colliders capable of reaching this regime (such as the Large Hadron Collider and the International Linear Collider) are costly and time-consuming to build; it is therefore important to explore new methods of accelerating particles to high energies. Plasma-based accelerators are particularly attractive because they are capable of producing accelerating fields that are orders of magnitude larger than those used in conventional colliders. In these accelerators, a drive beam (either laser or particle) produces a plasma wave (wakefield) that accelerates charged particles. The ultimate utility of plasma accelerators will depend on sustaining ultrahigh accelerating fields over a substantial length to achieve a significant energy gain. Here we show that an energy gain of more than 42 GeV is achieved in a plasma wakefield accelerator of 85 cm length, driven by a 42 GeV electron beam at the Stanford Linear Accelerator Center (SLAC). The results are in excellent agreement with the predictions of three-dimensional particle-in-cell simulations. Most of the beam electrons lose energy to the plasma wave, but some electrons in the back of the same beam pulse are accelerated with a field of approximately 52 GV m(-1). This effectively doubles their energy, producing the energy gain of the 3-km-long SLAC accelerator in less than a metre for a small fraction of the electrons in the injected bunch. This is an important step towards demonstrating the viability of plasma accelerators for high-energy physics applications.

Quality improvement guidelines for pediatric abscess and fluid drainage.

Image-guided drainage of abscesses and fluid collections is a valuable tool in the treatment of pediatric patients. It may obviate surgery or optimize the child's clinical condition for subsequent surgery. Compared with adults, several differences exist in terms of etiology, risks (especially radiation exposure), preprocedural imaging and planning, technical considerations, support issues such as sedation, and complications. Knowledge of these differences is important in the planning and treatment of these patients. In addition, a quality improvement plan can be used to assess practice performance.

Ultrasound-guided corticosteroid injection therapy for juvenile idiopathic arthritis: 12-year care experience.

BACKGROUND: Intra-articular corticosteroid injections are a safe and effective treatment for patients with juvenile idiopathic arthritis. The potential scope of care in ultrasound-guided corticosteroid therapy in children and a joint-based corticosteroid dose protocol designed to optimize interdisciplinary care are not found in the current literature. OBJECTIVE: The purpose of this study was to report the spectrum of care, technique and safety of ultrasound-guided corticosteroid injection therapy in patients with juvenile idiopathic arthritis and to propose an age-weight-joint-based corticosteroid dose protocol. MATERIALS AND METHODS: A retrospective analysis was performed of 198 patients (ages 21 months to 28 years) referred for treatment of juvenile idiopathic arthritis with corticosteroid therapy. Symptomatic joints and tendon sheaths were treated as prescribed by the referring rheumatologist. An age-weight-joint-based dose protocol was developed and utilized for corticosteroid dose prescription. RESULTS: A total of 1,444 corticosteroid injections (1,340 joints, 104 tendon sheaths) were performed under US guidance. Injection sites included small, medium and large appendicular skeletal joints (upper extremity 497, lower extremity 837) and six temporomandibular joints. For patients with recurrent symptoms, 414 repeat injections were performed, with an average time interval of 17.7 months (range, 0.5-101.5 months) between injections. Complications occurred in 2.6% of injections and included subcutaneous tissue atrophy, skin hypopigmentation, erythema and pruritis. CONCLUSION: US-guided corticosteroid injection therapy provides dynamic, precise and safe treatment of a broad spectrum of joints and tendon sheaths throughout the entire pediatric musculoskeletal system. An age-weight-joint-based corticosteroid dose protocol is effective and integral to interdisciplinary care of patients with juvenile idiopathic arthritis.

Generation of ultrahigh-brightness pre-bunched beams from a plasma cathode for X-ray free-electron lasers.

The longitudinal coherence of X-ray free-electron lasers (XFELs) in the self-amplified spontaneous emission regime could be substantially improved if the high brightness electron beam could be pre-bunched on the radiated wavelength-scale. Here, we show that it is indeed possible to realize such current modulated electron beam at angstrom scale by exciting a nonlinear wake across a periodically modulated plasma-density downramp/plasma cathode. The density modulation turns on and off the injection of electrons in the wake while downramp provides a unique longitudinal mapping between the electrons' initial injection positions and their final trapped positions inside the wake. The combined use of a downramp and periodic modulation of micrometers is shown to be able to produces a train of high peak current (17 kA) electron bunches with a modulation wavelength of 10's of angstroms - orders of magnitude shorter than the plasma density modulation. The peak brightness of the nano-bunched beam can be O(1021A/m2/rad2) orders of magnitude higher than current XFEL beams. Such prebunched, high brightness electron beams hold the promise for compact and lower cost XEFLs that can produce nanometer radiation with hundreds of GW power in a 10s of centimeter long undulator.

Safety of pediatric percutaneous liver biopsy performed by interventional radiologists.

OBJECTIVE: National data suggest that pediatric percutaneous liver biopsy is increasingly being performed by interventional radiologists rather than pediatric gastroenterologists. The objective of the present report is to describe the safety and effectiveness of percutaneous liver biopsy performed by interventional radiologists in a large cohort of children and to compare the results with the existing literature on biopsies performed by pediatric gastroenterologists. PATIENTS AND METHODS: The medical records of 249 children undergoing ultrasound-guided percutaneous liver biopsy by interventional radiologists were reviewed for adverse events and success of obtaining tissue. Two hundred ninety-four biopsies were reviewed. RESULTS: There were no deaths. There were 2 instances of a 2-g or greater drop in hemoglobin following biopsy, neither of which was associated with clinical signs of hemorrhage. A small, asymptomatic pneumothorax quickly resolved without treatment. One patient developed Klebsiella sepsis 48  hours after biopsy. In all but 1 case, an adequate sample size was obtained. This low incidence of adverse events compares favorably with existing published reports of morbidity and mortality following percutaneous liver biopsy performed by pediatric gastroenterologists. CONCLUSIONS: Ultrasound-guided percutaneous liver biopsy performed by experienced pediatric interventional radiologists in a children's hospital setting is as safe and effective as biopsy performed by pediatric gastroenterologists.

Infection in pediatric interventional radiology.

Interventional radiology in children involves nearly every aspect of infectious disease. Diagnosis, treatment, prophylaxis and disease transmission in infectious disease are a daily part of pediatric interventional radiology practice. This article will discuss each of these aspects of infection with respect to interventional radiology.