Publications by authors named "Michael Temple"

78 Publications

Pediatric May-Thurner Syndrome-Systematic review and individual patient data meta-analysis.

J Thromb Haemost 2021 Mar 2. Epub 2021 Mar 2.

The Hospital for Sick Children, Toronto, Ontario, Canada.

Background: The outcomes of deep vein thrombosis (DVT) in children with May-Thurner Syndrome (MTS) remain unclear.

Objectives: This systematic review and patient-level meta-analysis aims to describe the outcomes of children with MTS presenting with DVT.

Methods: A systematic review of the published literature was performed. Data related to patients <18 years diagnosed with MTS and DVT was extracted. Risk of bias was assessed using the Murad criteria. Outcomes included vessel patency post-treatment, DVT recurrence, and post-thrombotic syndrome (PTS). Predictive and explanatory models were developed for these outcomes.

Results: In total, 109 cases were identified (age range 4-17 years; 77 females) in 28 studies; 75% of patients had ≥1 additional risk factor for DVT. PTS was seen in 61% of patients, DVT recurrence in 38%, and complete vessel patency post-treatment in 65%. The models developed to predict and explain PTS performed poorly overall. Recurrent thrombosis (adjusted for age and patency) predicted PTS (odds ratio [OR] 3.36, 95% confidence interval [CI] 1.28-8.82). DVT management strategies (adjusted for age and DVT characteristics) predicted vessel patency (OR 2.10, 95% CI 1.43-3.08). Lack of complete vessel patency (adjusted for age and thrombophilia) predicted recurrent DVT (OR 2.70, 95% CI 1.09-6.67). Sensitivity analyses showed the same direction of effects for all outcomes.

Conclusions: PTS and DVT recurrence occur frequently in pediatric MTS. PTS prediction is complex and it was not possible to identify early predictors to guide clinical practice. Use of imaging-guided therapy and thrombus burden predicted venous patency, and lack of patency predicted DVT recurrence.
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http://dx.doi.org/10.1111/jth.15284DOI Listing
March 2021

Image-guided chest tube drainage in the management of chylothorax post cardiac surgery in children: a single-center case series.

Pediatr Radiol 2021 Jan 30. Epub 2021 Jan 30.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: In children, chylothorax post cardiac surgery can be difficult to treat, may run a protracted course, and remains a source of morbidity and mortality.

Objective: To analyze the experience with percutaneous image-guided chest-tube drainage in the management of post-cardiac-surgery chylothoraces in children.

Materials And Methods: We conducted a single-center retrospective case series of 37 post-cardiac-surgery chylothoraces in 34 children (20 boys; 59%), requiring 48 drainage procedures with placement of 53 image-guided chest tubes over the time period 2004 to 2015. We analyzed clinical and procedural details, adverse events and outcomes. Median age was 0.6 years, median weight 7.2 kg.

Results: Attempted treatments of chylothoraces prior to image-guided chest tubes included dietary restrictions (32/37, 86%), octreotide (12/37, 32%), steroids (7/37, 19%) and thoracic duct ligation (5/37, 14%). Image-guided chest tubes (n=43/53, 81%) were single unilateral in 29 children, bilateral in 4 (n=8/53, 15%), and there were two ipsilateral tubes in one (2/53, 4%). Effusions were isolated, walled-off, in 33/53 (62%). In 20/48 procedures (42%) effusions were septated/complex. The mean drainage through image-guided chest tubes was 17.3 mL/kg in the first 24 h, and 13.4 mL/kg/day from diagnosis to chest tube removal; total mean drainage from all chest tubes was 19.6 mL/kg/day. Nine major and 27 minor maintenance procedures were required during 1,207 tube-days (rate: 30 maintenance/1,000 tube-days). Median tube dwell time was 21 days (range 4-57 days). There were eight mild adverse events, three moderate adverse events and no severe adverse events related to image-guided chest tubes. Radiologic resolution was achieved in 26/37 (70%). Twenty-three children (68%) survived to discharge; 11 children (32%) died from underlying cardiac disease.

Conclusion: Management of chylothorax post-cardiac-surgery in children is multidisciplinary, requiring concomitant multipronged approaches, often through a protracted course. Multiple image-guided chest tube drainages can help achieve resolution with few complications. Interventional radiology involvement in tube care and maintenance is required. Overall, mortality remains high.
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http://dx.doi.org/10.1007/s00247-020-04928-2DOI Listing
January 2021

Magnetic Resonance Liver Lymphangiography for Investigation and Transhepatic Lymphatic Embolization for the Treatment of Protein-Losing Enteropathy.

J Vasc Interv Radiol 2021 02 29;32(2):327-329.e2. Epub 2020 Nov 29.

Division of Image Guided Therapy, Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, Canada; Medical Imaging Department, University of Toronto, ON, Canada.

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http://dx.doi.org/10.1016/j.jvir.2020.10.012DOI Listing
February 2021

Image guided sacroiliac joint corticosteroid injections in children: an 18-year single-center retrospective study.

Pediatr Rheumatol Online J 2020 Jun 17;18(1):52. Epub 2020 Jun 17.

Division of Image Guided Therapy, Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.

Background: Sacroiliitis is commonly seen in enthesitis-related arthritis (ERA), a subtype of juvenile idiopathic arthritis (JIA). Sacroiliitis is characterized by the inflammation of the sacroiliac (SI) joints (+/- adjacent tissues). The treatment options include systemic therapy with or without corticosteroid SI joint injections. Image guided SI joint injections are frequently requested in pediatric patients with sacroiliitis. The purpose of this study was to evaluate the feasibility and efficacy of SI joint injections in children with sacroiliitis.

Methods: A retrospective study of patients referred to Interventional Radiology (IR) for SI joint corticosteroid injections (2000-2018). Clinical information was collected from Electronic Patient Charts and procedural details from PACS. Efficacy was determined clinically, by MRI, or both when available.

Results: 50 patients (13.8 years; M:F = 35:15) underwent image-guided SI joint corticosteroid injections. Most common indications were JIA (84%) and inflammatory bowel disease (14%). 80% had bilateral injections. 80% were performed under general anesthesia and 20% under sedation. The corticosteroid of choice was triamcinolone hexacetonide in 98% of patients. Needle guidance and confirmation was performed using CT and fluoroscopy (54%), Cone Beam CT (CBCT, 46%), with initial ultrasound assistance in 34%. All procedures were technically successful without any complications. 32/50 patients had long-term follow-up (2 years); 21/32 (66%) had clinical improvement within 3-months. Of 15 patients who had both pre- and post-procedure MRIs, 93% showed short-term improvement. At 2 years, 6% of patients were in remission, 44% continued the same treatment and 47% escalated treatment.

Conclusion: Image-guided SI joint injections are safe and technically feasible in children. Imaging modalities for guidance have evolved, with CBCT being the current first choice. Most patients showed short-term clinical and imaging improvement, requiring long-term maintenance or escalation of medical treatment.
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http://dx.doi.org/10.1186/s12969-020-00435-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7301971PMC
June 2020

Magnetic Resonance Lymphangiography.

Radiol Clin North Am 2020 Jul 6;58(4):693-706. Epub 2020 May 6.

Department of Diagnostic Imaging, The Hospital for Sick Children and Medical Imaging, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.

Dynamic contrast-enhanced magnetic resonance lymphangiography is a novel technique to image central conducting lymphatics. It is performed by injecting contrast into groin lymph nodes and following passage of contrast through lymphatic system using T1-weighted MR images. Currently, it has been successfully applied to image and plan treatment of thoracic duct pathologies, lymphatic leaks, and other lymphatic abnormalities such as plastic bronchitis. It is useful in the assessment of chylothorax and chyloperitoneum. Its role in other areas such as intestinal lymphangiectasia and a variety of lymphatic anomalies is likely to increase.
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http://dx.doi.org/10.1016/j.rcl.2020.02.002DOI Listing
July 2020

Percutaneous removal of biliary stones post-liver transplant in a pediatric patient: Case report and review of the literature.

Pediatr Transplant 2020 06 23;24(4):e13715. Epub 2020 Apr 23.

Faculty of Medicine, University of Toronto, Toronto, ON, Canada.

This case report describes an 8-year-old girl who underwent a segmental LT for a primary diagnosis of citrullinemia at the age of 12 months. She presented with cholangitis secondary to stenosis of the biliary-enteric anastomosis. MRI revealed dilatation of intrahepatic bile ducts associated with multiple stones. An endoscopic approach failed to decompress the bile ducts and remove the stones. A percutaneous approach was then undertaken. After placement of a temporary external biliary drain for 12 days, a 26 French sheath was placed to access the bile ducts. Using a 14Fr flexible cystoscope, 80%-90% of the biliary stones were removed. This was followed by antegrade balloon dilatation of the biliary-enteric anastomosis. Two months later, the procedure was repeated, resulting in complete clearance of the biliary stones. An internal-external biliary drain was maintained in placed for 10 months. The patient has been asymptomatic, with no evidence of stone recurrence for 13 months after drain removal. Percutaneous biliary stone removal is commonly performed in adults with non-transplanted livers, especially in complex cases, and has also been shown to be successful in the pediatric population. However, it is rarely reported in transplanted livers in adults, and to the best of our knowledge, no pediatric cases have been reported. This case illustrates that this technique can be successfully utilized in pediatric LT patients.
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http://dx.doi.org/10.1111/petr.13715DOI Listing
June 2020

Hemodialysis Catheters in Infants: A Retrospective Single-Center Cohort Study.

J Vasc Interv Radiol 2020 05 15;31(5):778-786. Epub 2020 Apr 15.

Image Guided Therapy, Department of Medical Imaging, The Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada.

Purpose: Evaluate technical aspects and outcomes of insertion/maintenance of hemodialysis (HD) central venous catheter (CVC) during infancy.

Materials And Methods: Single-center retrospective study of 29 infants who underwent 49 HD-CVC insertions between 2002 and 2016. Demographics, procedural, and post-procedural details, interventional radiology (IR) maintenance procedures, technical modifications, complications, and outcomes were evaluated. Technical adjustments during HD-CVC placement to adapt catheter length to patient size were labeled "modifications." CVCs requiring return visit to IR were called IR-maintenance procedures. Mean age and weight at HD-CVC insertion were 117 days and 4.9 kg.

Results: Of the 29 patients, 13 (45%) required renal-replacement-therapy (RRT) as neonates, 10 (34%) commenced RRT with peritoneal dialysis (PD), and 19 (66%) with HD. Fifteen nontunneled and 34 tunneled HD-CVCs were inserted while patients were ≤1 year. Technical modifications were required placing 25/49 (51%) HD-CVCs: 5/15 (33%) nontunneled and 20/34 (59%) tunneled catheters (P = .08). Patients underwent ≤6 dialysis-cycles/patient during infancy (mean 2.3), and a mean of 4.1 and 49 HD-sessions/catheter for nontunneled and tunneled HD-CVCs, respectively. Mean primary and secondary device service, and total access site intervals for tunneled HD-CVCs were 75, 115, and 201 days, respectively. A total of 26 of 49 (53%) patients required IR-maintenance procedures. Nontunneled lines had greater catheter-related bloodstream infections per 1,000 catheter-days than tunneled HD-CVCs (9.25 vs. 0.85/1,000 catheter days; P = .02). Nineteen patients (65%) survived over 1 year. At final evaluation (December 2017): 8/19 survived transplantation, 5/19 remained on RRT, 2/19 completely recovered, 1/19 lost to follow-up, and 3 died at 1.3, 2, and 10 years.

Conclusions: Placement/maintenance of HD-CVCs in infants pose specific challenges, requiring insertion modifications, and IR-maintenance procedures to maintain function.
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http://dx.doi.org/10.1016/j.jvir.2020.01.020DOI Listing
May 2020

Use of Tissue Plasminogen Activator in Abdominal Abscesses in Children-A Single-Center Randomized Control Trial.

Can Assoc Radiol J 2020 Apr 13:846537120914263. Epub 2020 Apr 13.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada.

Purpose: To establish the efficacy of once-per-day intracavitary tissue plasminogen activator (tPA) in the treatment of pediatric intra-abdominal abscesses.

Methods: A single-center prospective, double-blinded, randomized controlled trial of the use of intracavitary tPA in abdominal abscesses in children. Patients were randomized to either tPA-treatment or saline-treatment groups. Primary outcome was drainage catheter dwell (hours). Secondary outcomes were length of hospital stay, times to discharge, clinical and sonographic resolution, and adverse events (AEs).

Results: Twenty-eight children were randomized to either group (n = 14 each). Demographics between groups were not significantly different (age = .28; weight = .40; gender = .44). There were significantly more abscesses in the tPA-treated group ( = .03). Abscesses were secondary to perforated appendicitis (n = 25) or postappendectomy (n = 3). Thirty-four abscesses were drained, 4 aspirated, 3 neither drained/aspirated. There was no significant difference in number of drains ( = .14), drain size ( = .19), primary outcome ( = .077), or secondary outcomes found. No procedural or intervention drug-related AEs occurred. No patient in the saline-treated group required to be switched/treated with tPA.

Conclusion: No significant difference in the length of catheter dwell time, procedure time to discharge, or time to resolution was found. Intracavitary tPA was not associated with morbidity or mortality. The results neither support nor negate routine use of tPA in the drainage of intra-abdominal abscess in children. It is possible that a multicentre study with a larger number of patients may answer this question more definitively.
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http://dx.doi.org/10.1177/0846537120914263DOI Listing
April 2020

Evaluation of implanted venous port-a-caths in children with medical complexity and neurologic impairment.

Pediatr Radiol 2019 09 13;49(10):1354-1361. Epub 2019 Jul 13.

Image Guided Therapy Centre, Diagnostic Imaging Department, The Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: Children with medical complexity and associated neurologic impairment frequently face difficulties with venous access. Intermittently they require urgent intravenous administration of fluids and medication.

Objective: To analyze the use of implanted port-a-caths in children with medical complexity who have neurologic impairment and difficult venous access.

Materials And Methods: We performed a single-center observational study of port-a-caths placed by interventional radiologists in children with medical complexity with neurologic impairment. We analyzed peripheral intravenous access attempts, peripheral intravenous starts, peripheral intravenous complications, alternative temporary central venous access devices, port-a-cath insertions, catheter days, access days, port-a-cath-related complications, hospital admissions and emergency department visits. We compared the year pre port-a-cath to the year post port-a-cath.

Results: Twenty-one children with medical complexity with neurologic impairment (10 boys, 11 girls; median age 4.1 years; median weight 13.7 kg) underwent 26 port-a-cath insertions (median catheter days 787). In the year post port-a-cath compared to pre port-a-cath there was a highly significant reduction (P<0.001) in numbers of peripheral intravenous attempts, peripheral intravenous starts and skin punctures; and a significant reduction (P<0.05) in need for other devices, number of emergency department visits, emergency department visits resulting in hospital admissions, and total admissions. Adverse events were graded as mild (n=18), moderate (n=6) and severe (n=0).

Conclusion: Port-a-cath placement in children with medical complexity with neurologic impairment significantly reduced all peripheral intravenous attempts, peripheral intravenous starts, skin punctures, total number of emergency department visits, visits culminating in admission, and total number of inpatient admissions. Advantages must be considered against potential port-a-cath-related adverse events.
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http://dx.doi.org/10.1007/s00247-019-04470-wDOI Listing
September 2019

Experience with Compressed Gelfoam Plugs in Children during Liver Biopsies and Other IR Procedures: A Retrospective Single-Center Case Series.

J Vasc Interv Radiol 2019 Nov 13;30(11):1855-1862. Epub 2019 Jun 13.

Department of Diagnostic Imaging, Division of Image Guided Therapy, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.

Purpose: To analyze the experience using compressed gelfoam plugs (CGPs) in children during liver biopsies and other interventional procedures.

Materials And Methods: This was a single-center, retrospective, consecutive case series of 477 various pediatric interventional radiology procedures using CGPs (January 2012 to December 2016) performed on 397 children (209 males, 188 females; median age, 7 years [range, 9 days-17.8 years]; median weight, 18 kg [range, 2.7-141 kg]). Of 477 procedures, most (n = 371) were liver biopsies, 98 were biopsies of other organs, and 8 were non-biopsy procedures. Analysis focused on liver biopsies.

Results: Of liver biopsies, a median of 2 CGPs were used per procedure, and the mean drop in hemoglobin was -0.36 g/dl (-3.0% change). Thirty-seven mild, 8 moderate, 2 severe, and 1 life-threatening (an anaphylaxis to CGP) adverse events (AEs) occurred. Analysis of liver biopsies with AEs showed significant association between number of passes, cores, and focal-type lesions (unadjusted logistic regression: P = .007, P = .022, P = .028, respectively) and age, weight, and number of passes (adjusted multiple logistic regression: P = .006, P = .032, P = .046, respectively). Technical problems relating to CGP deployment were noted in 5 (1%), without any AEs.

Conclusions: CGPs were used in a wide variety of procedures and organs in children. There was 1 life-threatening AE resulting from the rare risk of anaphylaxis caused by the gelfoam-containing plug. After liver biopsies, transfusion was required in 2/371 (0.5%) procedures, 1 related to pre-biopsy anemia (0.25%).
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http://dx.doi.org/10.1016/j.jvir.2019.04.004DOI Listing
November 2019

Use of the Transrectal Ultrasound Probe in Aspiration and Drainage in Pediatric Patients: A Retrospective Observational Study.

J Vasc Interv Radiol 2019 Jun 5;30(6):908-914. Epub 2019 Apr 5.

Division of Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, Department of Medical Imaging, University of Toronto, 555 University Avenue, 2810B, Toronto, Canada M5G 1X8.

Purpose: To retrospectively evaluate the safety and efficacy of transrectal ultrasound (TRUS) probe use for aspiration and drainage of pelvic abscesses in children.

Materials And Methods: Patient demographics, procedural details, technical success, safety, and clinical course of TRUS procedures were retrospectively analyzed. Between 2007 and 2016, 118 TRUS-guided procedures were performed in 115 children (60 males, 55 females); median age was 12.4 years (range, 2.4-17.9 years) and median weight was 45 kg (range, 12.6-112 kg). Ten children were 5 years of age or younger.

Results: In total, 113/118 procedures were performed under general anesthesia. The rectum accommodated the probe and needle guide without resistance in all children (technical feasibility, 100%). Abscesses were anterior to the rectum in 116/118 and posterior in 2/118. One hundred twelve collections were drained, 4 were aspirated, and 2 procedures were aborted, both subsequently successfully drained (2 and 3 days later). One patient underwent repeat drainage after 28 months. No major complications were reported. Median times to temperature normalization was 0 days (mean, 1.2; range, 0-13 days), catheter dwell time 5 days (mean, 6; range, 2-21 days), drain removal to discharge 1 day (mean, 2; range, 0-41 days), and follow-up 117 days (mean, 195; range, 5-2,690 days).

Conclusions: TRUS-guided drainage using the TRUS probe and needle guide is a safe and effective method for aspiration and drainage of pelvic abscesses in children as young as 2 years.
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http://dx.doi.org/10.1016/j.jvir.2018.09.023DOI Listing
June 2019

Pulmonary endarterectomy in a toddler with chronic thromboembolic pulmonary hypertension after Denver shunt.

J Thorac Cardiovasc Surg 2019 06 2;157(6):e409-e410. Epub 2019 Mar 2.

Division of Thoracic Surgery, University Health Network, University of Toronto, Toronto, Ontario, Canada.

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http://dx.doi.org/10.1016/j.jtcvs.2019.02.085DOI Listing
June 2019

Trends in Use of Electronic Health Records in Pediatric Office Settings.

J Pediatr 2019 03 5;206:164-171.e2. Epub 2018 Dec 5.

Department of Biomedical Informatics, Vanderbilt University, Nashville, TN; Department of Biomedical Informatics, Vanderbilt University, Nashville, TN. Electronic address:

Objectives: To determine the prevalence and functionalities of electronic health records (EHRs) and pediatricians' perceptions of EHRs.

Study Design: An 8-page self-administered questionnaire sent to 1619 randomly selected nonretired US American Academy of Pediatrics members in 2016 was completed by 709 (43.8%). Responses were compared with surveys in 2009 and 2012.

Results: The percent of pediatricians who were using EHRs increased from 58% in 2009 and 79% in 2012 to 94% in 2016. Those with fully functional EHRs, including pediatric functionality, more than doubled from 8.2% in 2012 to 16.9% in 2016 (P = .01). Fully functional EHRs lacking pediatric functionality increased slightly from 7.8% to 11.1% (P = .3), and the percentage of pediatricians with basic EHRs remained stable (30.4% to 31.0%; P < .3). The percentage of pediatricians who lacked basic EHR functionality or who reported no EHR decreased (from 53.6% to 41.0%; P < .001). On average, pediatricians spent 3.4 hours per day documenting care.

Conclusions: Although the adoption of EHRs has increased, >80% of pediatricians are working with EHRs that lack optimal functionality and 41% of pediatricians are not using EHRs with even basic functionality. EHRs lacking pediatric functionality impact the health of children through increased medical errors, missed diagnoses, lack of adherence to guidelines, and reduced availability of child-specific information. The pediatric certification outlined in the 21st Century Cures Act may result in improved EHR products for pediatricians.
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http://dx.doi.org/10.1016/j.jpeds.2018.10.039DOI Listing
March 2019

Phenotype risk scores identify patients with unrecognized Mendelian disease patterns.

Science 2018 03;359(6381):1233-1239

Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, USA.

Genetic association studies often examine features independently, potentially missing subpopulations with multiple phenotypes that share a single cause. We describe an approach that aggregates phenotypes on the basis of patterns described by Mendelian diseases. We mapped the clinical features of 1204 Mendelian diseases into phenotypes captured from the electronic health record (EHR) and summarized this evidence as phenotype risk scores (PheRSs). In an initial validation, PheRS distinguished cases and controls of five Mendelian diseases. Applying PheRS to 21,701 genotyped individuals uncovered 18 associations between rare variants and phenotypes consistent with Mendelian diseases. In 16 patients, the rare genetic variants were associated with severe outcomes such as organ transplants. PheRS can augment rare-variant interpretation and may identify subsets of patients with distinct genetic causes for common diseases.
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http://dx.doi.org/10.1126/science.aal4043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959723PMC
March 2018

Increased risk of symptomatic upper-extremity venous thrombosis with multiple peripherally inserted central catheter insertions in pediatric patients.

Pediatr Radiol 2018 07 27;48(7):1013-1020. Epub 2018 Feb 27.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.

Background: Peripherally inserted central catheters (PICCs) are associated with superficial and deep venous thrombosis of the arm.

Objective: The purpose of this study was to analyze the sequelae of repeated upper limb PICC insertions in children, in terms of the frequency of upper limb thrombosis in this patient group.

Materials And Methods: The study population included all children who underwent their first successful arm PICC insertion between January 2010 and December 2015. We included subsequent ipsilateral arm PICCs in the analysis. Patients were followed until March 2016 or until any alternative central venous line insertion. For each PICC insertion, we collected demographic variables and line characteristics. We correlated all symptomatic deep and superficial thromboses of the arm with the PICC database.

Results: Applying inclusion and exclusion criteria, 2,180 PICCs remained for analysis. We identified first, second, third and fourth PICC insertions in the same arm in 1,955, 181, 38 and 6 patients, respectively. In total there were 57 upper body deep symptomatic thrombotic events. An increasing odds ratio was seen with higher numbers of PICC insertions, which was significant when comparing the first with the third and fourth PICC insertions in the same arm (odds ratio [OR] 6.00, 95% confidence interval [CI] 2.25-16.04, P=0.0004). Double-lumen PICCs were associated with a significantly higher risk of thrombosis than single lumen (OR 2.77, 95% CI 1.72-4.47, P=0.0003).

Conclusion: Repetitive PICC insertions in the same arm are associated with an increased risk of symptomatic thrombosis. Double-lumen PICCs are associated with a higher risk of thrombosis compared to single-lumen lines.
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http://dx.doi.org/10.1007/s00247-018-4096-xDOI Listing
July 2018

Simulating thermal effects of MR-guided focused ultrasound in cortical bone and its surrounding tissue.

Med Phys 2018 Feb 25;45(2):506-519. Epub 2017 Dec 25.

Centre for Image Guided Innovation and Therapeutic Intervention, Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada.

Purpose: Magnetic resonance-guided focused ultrasound (MRgFUS) is emerging as a treatment alternative for osteoid osteoma and painful bone metastases. This study describes a new simulation platform that predicts the distribution of heat generated by MRgFUS when applied to bone tissue.

Methods: Calculation of the temperature distribution was performed using two mathematical models. The first determined the propagation and absorption of acoustic energy through each medium, and this was performed using a multilayered approximation of the Rayleigh integral method. The ultrasound energy distribution derived from these equations could then be converted to heat energy, and the second mathematical model would then use the heat generated to determine the final temperature distribution using a finite-difference time-domain application of Pennes' bio-heat transfer equation. Anatomical surface geometry was generated using a modified version of a mesh-based semiautomatic segmentation algorithm, and both the acoustic and thermodynamic models were calculated using a parallelized algorithm running on a graphics processing unit (GPU) to greatly accelerate computation time. A series of seven porcine experiments were performed to validate the model, comparing simulated temperatures to MR thermometry and assessing spatial, temporal, and maximum temperature accuracy in the soft tissue.

Results: The parallelized algorithm performed acoustic and thermodynamic calculations on grids of over 10 voxels in under 30 s for a simulated 20 s of heating and 40 s of cooling, with a maximum time per calculated voxel of less than 0.3 μs. Accuracy was assessed by comparing the soft tissue thermometry to the simulation in the soft tissue adjacent to bone using four metrics. The maximum temperature difference between the simulation and thermometry in a region of interest around the bone was measured to be 5.43 ± 3.51°C average absolute difference and a percentage difference of 16.7%. The difference in heating location resulted in a total root-mean-square error of 4.21 ± 1.43 mm. The total size of the ablated tissue calculated from the thermal dose approximation in the simulation was, on average, 67.6% smaller than measured from the thermometry. The cooldown was much faster in the simulation, where it decreased by 14.22 ± 4.10°C more than the thermometry in 40 s after sonication ended.

Conclusions: The use of a Rayleigh-based acoustic model combined with a discretized bio-heat transfer model provided a rapid three-dimensional calculation of the temperature distribution through bone and soft tissue during MRgFUS application, and the parallelized GPU algorithm provided the computational speed that would be necessary for an intraoperative treatment planning software platform.
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http://dx.doi.org/10.1002/mp.12704DOI Listing
February 2018

MR Lymphangiography in Children: Technique and Potential Applications.

Radiographics 2017 Oct;37(6):1775-1790

From the Department of Diagnostic Imaging (G.B.C., J.G.A., M.T.) and Division of Image Guided Therapy, Department of Diagnostic Imaging (J.G.A., M.T.), The Hospital for Sick Children, Medical Imaging, University of Toronto, 555 University Ave, Toronto, ON, Canada M5G 1X8; and Center for Lymphatic Imaging and Interventions, Children's Hospital of Philadelphia, Hospital of the University of Pennsylvania, Philadelphia, Pa (M.I.).

The lymphatic system, an important component of the circulatory system with essential physiologic functions, can be affected by various disease processes. There has been a delay in the development of effective imaging methods for the lymphatic system due to its small size, which limits visualization as well as introduction of contrast material. Traditionally, the lymphatic system has been imaged by injecting contrast material or radiotracers into the feet or hands. This is not sufficient for assessment of the central conducting lymphatics (CCLs) (such as the thoracic duct or the cisterna chyli). Fluoroscopic intranodal lymphangiography with injection of oil-based contrast material into groin lymph nodes improves visualization of CCLs but is limited in practice owing to the use of radiation and the potential risk for paradoxical embolization in children with left-to-right shunt. Dynamic contrast material-enhanced (DCE) magnetic resonance (MR) lymphangiography, which is performed by injecting gadolinium-based contrast material into groin lymph nodes, overcomes these limitations. T2-weighted imaging plays a complementary role to DCE MR lymphangiography in the assessment of CCLs. DCE MR lymphangiography demonstrates preserved integrity or any abnormality of the CCLs (including blockage or leak). The technique has recently been used in evaluating pulmonary lymphatic perfusion syndrome in children with plastic bronchitis, neonatal lymphatic flow disorders, and nontraumatic chylothorax. It is useful in identification of the source of chylous ascites and contributes to understanding of the anatomy of lymphatic malformations. It is successfully used for planning of embolization of aberrant lymphatic channels in a variety of lymphatic flow disorders. This review discusses the anatomy and function of the lymphatic system, the evolution of imaging of the lymphatic system, and DCE MR lymphangiography technique and its applications in children. RSNA, 2017.
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http://dx.doi.org/10.1148/rg.2017170014DOI Listing
October 2017

Perforations associated with peripherally inserted central catheters in a neonatal population.

Pediatr Radiol 2018 01 6;48(1):109-119. Epub 2017 Oct 6.

Division of Neonatology, Department of Pediatrics, The Hospital for Sick Children, 555 University Ave., Toronto, ON, M5G 1X8, Canada.

Background: Peripherally inserted central catheters (PICCs) are increasingly used in neonates but perforations can result in devastating complications such as pericardial and pleural effusions. Identifying risk factors may guide surveillance and reduce morbidity and mortality.

Objective: To determine the risk factors for PICC perforation in neonates.

Materials And Methods: Retrospective case:control (1:2) study of neonates admitted between 2004-2014. Charts and imaging were reviewed for clinical and therapeutic risk factors.

Results: Among 3,454 PICCs, 15 cases of perforation (incidence 0.4%, 5 pericardial effusions, 10 pleural effusions) were matched to 30 controls, based on gestation and insertion date. Timing of perforations post-insertion was median 4 days for pericardial effusions and 21.5 days for pleural effusions. A risk factor for pericardial effusion was lower weight at PICC insertion compared with controls. There were no statistically significant differences between cases and controls in catheter material, insertion site, PICC size and lumen number. Among upper limb PICCs, pericardial effusions were associated with tip positions more proximal to the heart at insertion (P=0.005) and at perforation (P=0.008), compared with controls. Pleural effusions were associated with tip positions more distal from the heart at perforation (P=0.008). Within 48 h before perforation, high/medium risk infusions included total parenteral nutrition (100% cases vs. 56.7% controls, P=0.002) and vancomycin (60% cases vs. 23.3% controls, P=0.02).

Conclusion: PICC-associated pericardial effusions and pleural effusions are rare but inherent risks and can occur at any time after insertion. Risk factors and etiologies are multifactorial, but PICC tip position may be a modifiable risk factor. To mitigate this risk, we have developed and disseminated guidelines for target PICC positions and routinely do radiographs to monitor PICCs for migration and malposition in our NICU. The increased knowledge of risk profiles from this study has helped focus surveillance efforts and facilitate early recognition and treatment.
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http://dx.doi.org/10.1007/s00247-017-3983-xDOI Listing
January 2018

Technique, Safety, and Yield of Bone Biopsies for Histomorphometry in Children.

J Vasc Interv Radiol 2017 Nov 18;28(11):1577-1583. Epub 2017 Aug 18.

Division of Image Guided Therapy, Diagnostic Imaging, Department of Medical Imaging, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8 Canada.

Purpose: To evaluate image-guided bone biopsy for bone histomorphometry to assess osteoporosis in children with respect to safety and yield.

Materials And Methods: A single-center retrospective review was performed of 79 bone biopsies in 73 patients performed between 2007 and 2015. Biopsies of the iliac bone were performed under general anesthesia, after tetracycline labeling, using a Rochester needle (Medical Innovations International, Inc, Rochester, Minnesota). Ultrasound and fluoroscopic guidance were used in all procedures. Biopsy technique, technical success, safety, and histomorphometry results (complete, incomplete, none) were analyzed.

Results: There were 41 male patients (51.8%). Technical success was achieved in 76/79 (96%) procedures. Of 79 biopsies, 75 (95%) were uneventful. Unplanned overnight observation was required in 3 (minor SIR grade B), and prolonged hospital stay owing to hematoma causing nerve compression pain was required in 1 (major SIR grade D). Complete histomorphometric reports were obtained in 69 (87%) procedures, incomplete reports were obtained in 7 (9%), and no reports were obtained in 3(4%). Incomplete reports were insufficient to provide a definitive diagnosis or guide treatment. Histomorphometry impacted subsequent therapy in 69 (87%) biopsies.

Conclusions: Image-guided bone biopsy for osteoporosis using the Rochester needle is a valuable and safe technique for establishing the diagnosis of osteoporosis and directing treatment based on histomorphometry results.
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http://dx.doi.org/10.1016/j.jvir.2017.07.003DOI Listing
November 2017

Plastic bronchitis: a rare complication of long-term haemodialysis catheter placement in a child.

Pediatr Nephrol 2017 09 22;32(9):1635-1638. Epub 2017 Jun 22.

Division of Nephrology, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.

Background: Despite peritoneal dialysis being the preferred mode of renal replacement therapy in neonates and infants, long-term haemodialysis may be necessary in a minority of patients with its attendant risks.

Case Diagnosis/treatment: This case identifies plastic bronchitis as a rare yet serious complication of long-term large bore vascular access when a vessel-sparing approach is not possible.

Conclusions: An appropriately sized catheter should be used for the dialytic therapy required and to optimize access survival.
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http://dx.doi.org/10.1007/s00467-017-3717-1DOI Listing
September 2017

Peripherally Inserted Central Catheters in Pediatric Patients: To Repair or Not Repair.

Cardiovasc Intervent Radiol 2017 Jun 30;40(6):845-851. Epub 2017 Jan 30.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Avenue Toronto, Toronto, ON, M5G 1X8, Canada.

Introduction: Preservation of venous access in children is a major concern in pediatric interventional radiology. If a peripherally inserted central catheter (PICC) breaks, there are two options: repair the line with a repair kit or exchange the line over a wire in the interventional suite. The purpose of this study is to assess the outcome of PICC repairs in children and to compare these with the outcomes of PICC exchange.

Materials And Methods: This is a single-center, retrospective study of central line-associated bloodstream infection (CLABSI) following management of externally broken PICCs (2010-2014). The occurrence of CLABSI within 30 days after repair (Group A) or exchange (Group B) of a line was analyzed, as well as PICCs exchanged following an initial and failed repair.

Results: A total of 235 PICC breaks were included in the study, of which 161 were repaired, and 116 of whom were successful (68%, Group A). No repair was performed in 74 PICCs-55/74 of these were exchanged over a wire (74%, Group B), and 19/74 lines were removed. The 30 days post-repair CLABSI rate (Group A) was 2.0 infections per 1000 catheter days, and the calculated risk was 4.3%. In comparison the 30 days post-exchange CLABSI rate (Group B) was 4.0 per 1000 catheter days and the calculated risk 10.9%. This difference was significant when adjusted for antibiotic use (OR 3.87; 95% CI 1.07-14.0, p = 0.039).

Conclusion: The results of this study support repairing a broken PICC instead of removing or replacing the line.
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http://dx.doi.org/10.1007/s00270-017-1580-xDOI Listing
June 2017

Establishing a clinical service for the treatment of osteoid osteoma using magnetic resonance-guided focused ultrasound: overview and guidelines.

J Ther Ultrasound 2016 20;4:16. Epub 2016 May 20.

The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON M5G 1X8 Canada.

Recent studies have demonstrated the effectiveness of magnetic resonance-guided focused ultrasound (MRgFUS) in the treatment of osteoid osteoma (OO), a painful, benign bone tumor. As MRgFUS is a noninvasive and radiation-free treatment, it stands to replace the current standard of care, percutaneous radiofrequency, or laser thermal ablation. Within an institution, creation of a clinical OO MRgFUS treatment program would not only provide cutting edge medical treatment at the current time but would also establish the foundation for an MRgFUS clinical service to introduce treatments currently under development into clinical practice in the future. The purpose of this document is to provide information to facilitate creation of a clinical service for MRgFUS treatment of OO by providing (1) recommendations for the multi-disciplinary management of patients and (2) guidelines regarding current best practices for MRgFUS treatment. This paper will discuss establishment of a multi-disciplinary clinic, patient accrual, inclusion/exclusion criteria, diagnosis, preoperative imaging, patient preparation, anesthesia, treatment planning, targeting and treatment execution, complication avoidance, and patient follow-up to assure safety and effectiveness.
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http://dx.doi.org/10.1186/s40349-016-0059-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4873984PMC
May 2016

IR Approaches to Difficult Removals of Totally Implanted Venous Access Port Catheters in Children: A Single-Center Experience.

J Vasc Interv Radiol 2016 Jun 19;27(6):876-81. Epub 2016 Apr 19.

Division of Image Guided Therapy, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada. Electronic address:

Purpose: To identify factors associated with adherence of implanted venous access port catheters in children and describe technical strategies for removing "stuck" ports.

Materials And Methods: A retrospective single-center review of port removals was conducted between 2003 and 2012. Cases were identified through radiology reports. Clinical details (eg, demographics, disease, port dwell time, interventional techniques) were obtained through patient charts. Cases were classified as difficult removals if there was documented adherence to soft tissues or vein, or simple removals if no difficulty was recorded. Difficult removals were categorized and graded on increasing invasiveness of techniques required. Successful removal was defined as complete removal of the port catheter. Difficult removals were compared with simple removals for factors associated with difficult removal. Of all removals (N = 1,306), 58 were classified as difficult removals (4%).

Results: Using various techniques, 57 of 58 (98%) adherent port catheters were successfully removed. Factors identified with difficult removals included primary diagnosis of acute lymphoblastic leukemia (ALL) (78% vs 37%, P < .0001), age at insertion (3.7 y vs 5.4 y, P = .0019), and port dwell time (median 1,087 d vs 616 d, P < .0001).

Conclusions: Difficulty removing port catheters in children is uncommon. Port catheters can usually be removed successfully using various IR techniques ranging in invasiveness. There is an association of difficult removal with early age at insertion, ALL diagnosis, and long port dwell time. Awareness of these factors may help physicians inform parents of potential difficulties and plan the removal procedure.
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http://dx.doi.org/10.1016/j.jvir.2016.02.021DOI Listing
June 2016

Natural Language Processing for Cohort Discovery in a Discharge Prediction Model for the Neonatal ICU.

Appl Clin Inform 2016 24;7(1):101-15. Epub 2016 Feb 24.

Department of Biomedical Informatics Vanderbilt University , Nashville, TN.

Objectives: Discharging patients from the Neonatal Intensive Care Unit (NICU) can be delayed for non-medical reasons including the procurement of home medical equipment, parental education, and the need for children's services. We previously created a model to identify patients that will be medically ready for discharge in the subsequent 2-10 days. In this study we use Natural Language Processing to improve upon that model and discern why the model performed poorly on certain patients.

Methods: We retrospectively examined the text of the Assessment and Plan section from daily progress notes of 4,693 patients (103,206 patient-days) from the NICU of a large, academic children's hospital. A matrix was constructed using words from NICU notes (single words and bigrams) to train a supervised machine learning algorithm to determine the most important words differentiating poorly performing patients compared to well performing patients in our original discharge prediction model.

Results: NLP using a bag of words (BOW) analysis revealed several cohorts that performed poorly in our original model. These included patients with surgical diagnoses, pulmonary hypertension, retinopathy of prematurity, and psychosocial issues.

Discussion: The BOW approach aided in cohort discovery and will allow further refinement of our original discharge model prediction. Adequately identifying patients discharged home on g-tube feeds alone could improve the AUC of our original model by 0.02. Additionally, this approach identified social issues as a major cause for delayed discharge.

Conclusion: A BOW analysis provides a method to improve and refine our NICU discharge prediction model and could potentially avoid over 900 (0.9%) hospital days.
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http://dx.doi.org/10.4338/ACI-2015-09-RA-0114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4817338PMC
December 2016

Ultrasound-Guided Thrombin Injection for the Treatment of Femoral Pseudoaneurysm in Pediatric Patients.

J Vasc Interv Radiol 2016 Apr;27(4):519-23

Division of Imaging Guided Therapy, Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, 555 University Ave., Toronto, ON, Canada M5G 1X8. Electronic address:

Eight patients with nine femoral pseudoaneurysms were treated with 13 ultrasound-guided thrombin injections. Mean patient age was 3.3 years (range, 5 mo to 13.6 y), mean pseudoaneurysm diameter was 2.0 cm ± 0.6, and mean thrombin dose was 119 IU (500 IU/mL ± 116; 0.95 CI). Mean follow-up was 27 days (range, 7-120 d). Eight pseudoaneurysms were successfully treated, and one failed to close as a result of arterial wall disease. No complications were observed. The approach used at the authors' pediatric institution resulted in safe and effective treatment of femoral pseudoaneurysms.
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http://dx.doi.org/10.1016/j.jvir.2015.12.756DOI Listing
April 2016

Predicting Discharge Dates From the NICU Using Progress Note Data.

Pediatrics 2015 Aug;136(2):e395-405

Departments of Biomedical Informatics, and.

Background And Objectives: Discharging patients from the NICU may be delayed for nonmedical reasons including the need for medical equipment, parental education, and children's services. We describe a method to predict which patients will be medically ready for discharge in the next 2 to 10 days, providing lead time to address nonmedical reasons for delayed discharge.

Methods: A retrospective study examined 26 features (17 extracted, 9 engineered) from daily progress notes of 4693 patients (103,206 patient-days) from the NICU of a large, academic children's hospital. These data were used to develop a supervised machine learning problem to predict days to discharge (DTD). Random forest classifiers were trained by using examined features and International Classification of Diseases, Ninth Revision-based subpopulations to determine the most important features.

Results: Three of the 4 subpopulations (premature, cardiac, gastrointestinal surgery) and all patients combined performed similarly at 2, 4, 7, and 10 DTD with area under the curve (AUC) ranging from 0.854 to 0.865 at 2 DTD and 0.723 to 0.729 at 10 DTD. Patients undergoing neurosurgery performed worse at every DTD measure, scoring 0.749 at 2 DTD and 0.614 at 10 DTD. This model was also able to identify important features and provide "rule-of-thumb" criteria for patients close to discharge. By using DTD equal to 4 and 2 features (oral percentage of feedings and weight), we constructed a model with an AUC of 0.843.

Conclusions: Using clinical features from daily progress notes provides an accurate method to predict when patients in the NICU are nearing discharge.
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http://dx.doi.org/10.1542/peds.2015-0456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524203PMC
August 2015

The percutaneous cecostomy tube in the management of fecal incontinence in children.

J Vasc Interv Radiol 2015 Feb 17;26(2):189-95. Epub 2014 Dec 17.

Department of Diagnostic Imaging, Hospital for Sick Children. Electronic address:

Purpose: To retrospectively evaluate experience with percutaneous cecostomies and their long-term outcomes.

Materials And Methods: Between June 1994 and March 2009, 290 patients (mean age, 10.1 y) with fecal incontinence underwent percutaneous cecostomy tube placement and subsequent tube management. Technical success, procedural complications, and long-term follow-up until March 2012 were evaluated.

Results: A cecostomy was successfully placed in 284 patients (98%), and 257 of 280 patients (92%) underwent a successful exchange to a low-profile tube. A total of 1,431 routine exchanges to low-profile tubes were reviewed in 258 patients (mean, 1.6 ± 1.3 routine tube changes per 1,000 days). Eighty-five patients (29%) experienced one or more early problems after cecostomy, and 10 (3%) had major complications. In the total 463,507 tube-days, 938 late problems were noted: 917 (98%) minor and 22 (2%) major. Forty patients had the cecostomy catheter removed and 141 "graduated" to an adult health care facility.

Conclusions: The percutaneous cecostomy procedure provides a safe management option for fecal incontinence in the pediatric population.
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http://dx.doi.org/10.1016/j.jvir.2014.10.015DOI Listing
February 2015

Image-guided pediatric ureteric stent insertions: an 11-year experience.

J Vasc Interv Radiol 2014 Aug 14;25(8):1265-71. Epub 2014 May 14.

Image Guided Therapy, Diagnostic Imaging, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8. Electronic address:

Purpose: To report the technical success and complication rates for double J ureteric stent placements by interventional radiologists in children.

Materials And Methods: A retrospective analysis of double J ureteric stents placed between January 2001 and December 2011 was conducted. Data collected included patient demographics, procedural details (indication, double J stent size, access approach, concurrent procedures), technical and functional success, tube dwell time, and procedure-related complications. Descriptive statistics were employed. Placement of 59 double J ureteric stents was attempted in 49 procedures performed on 35 pediatric patients (26 boys and 9 girls) with a mean age of 7.3 years (range, 22 d-17.9 y; median age, 4 y) and a mean weight of 22 kg (range, 2.5-70 kg).

Results: There were 44 de novo double J stent insertion attempts: 20 one-stage procedures (17 anterograde, 3 retrograde through the urethra) and 24 two-stage anterograde procedures through an existing nephrostomy tube. There were 15 exchanges; 11 were anterograde, and 4 were retrograde (2 urethral, 2 Mitrofanoff). Of 49 procedures, 15 were performed as combined procedures with a urologist. Technical success was 95% (56 of 59), and primary functional success was 95% (53 of 56). Complications included two minor complications occurring during the procedure and four complications occurring after the procedure.

Conclusions: Image-guided insertion of a double J ureteric stent is an effective treatment for pediatric urologic obstructive conditions. The procedure is both technically and functionally successful in a high percentage of pediatric patients.
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http://dx.doi.org/10.1016/j.jvir.2014.03.028DOI Listing
August 2014