Philip John

SickKids, Toronto, Ontario, Canada

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Publications (37)89.17 Total impact

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    ABSTRACT: The purpose of this article is to describe the principles and various techniques of MR angiography (MRA) that can be applied to pediatric body imaging and the current noncardiac, nonneurologic applications of MRA of children. The choice between CT angiography and MRA for body imaging should depend on the clinical query, ROI, and vessel size. MRA is useful for assessment of stenosis of the main renal artery, portal hypertension, tumor vascularity, vascular malformations, generalized vasculopathy in vasculitis and syndromes, and thoracic outlet syndrome.
    American Journal of Roentgenology 07/2015; 205(1):173-184. DOI:10.2214/AJR.14.13795 · 2.73 Impact Factor
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    ABSTRACT: Hepatic venous pressure gradient (HVPG) is an indirect measure of portal venous pressure in cirrhosis, which is valid in cirrhotic adults for evaluating the severity of portal hypertension, predicting outcomes, and guiding therapeutic decisions. Published data on the measurement of HVPG in children is sparse. To determine the feasibility and safety of undertaking HVPG measurements in children. Children who underwent HVPG measurements between 2000 and 2011 were identified from our Interventional Radiology database. Medical charts were reviewed for clinical, procedural and outcome data. 49 patients (25 male, mean age 8.2 ± 5.6y) underwent 52 HVPG measurements. Diagnoses included cirrhosis (n = 7), acute liver failure (n = 15), post-liver transplant (n = 6), post-bone marrow transplant (n = 9), vascular anomalies (n = 3) and others (n = 9). There were no complications related to HVPG measurement. HVPG values ranged between 0 and 28 mmHg, median 9.0 (range 0-28) mmHg, and were elevated above 6 mmHg in 30 patients. HVPG measurement is feasible and safe in children with severe liver disease. The clinical utility of HVPG measurements in managing children with portal hypertension or with acute liver diseases must now be determined.
    Journal of pediatric gastroenterology and nutrition 06/2013; 57(5). DOI:10.1097/MPG.0b013e3182a0e114 · 2.63 Impact Factor
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    ABSTRACT: Focal nodular hyperplasia (FNH), a benign liver tumour, has a characteristic appearance on diagnostic imaging (DI) and histology. The role of liver biopsy in children for the diagnosis of FNH is unclear. This study investigates the diagnostic accuracy of DI for FNH in children without comorbidities, compared to liver biopsy. A total of 304 consecutive patients (age <18 years) with a biopsied liver mass were retrospectively ascertained (1990-2010). Individuals with a history of malignancy, liver disease or syndromes with increased malignancy risk were excluded. DI and biopsy data were reviewed. After excluding 205 cases, 99 liver masses were studied. Based on histology, the most common diagnosis was hepatoblastoma (46/99, 44%) followed by FNH (23/99, 23%). The mean age at FNH diagnosis was 11.1 ± 5.2 years, with female preponderance (78%), and a median follow-up of 1.35 years (interquartile range 0.54, 4.20 years). 19/23 biopsy-proven FNH met standard criteria for FNH on DI. In 4/23 cases of biopsy-proven FNH, imaging did not suggest FNH. Two false positive cases included adenoma and fibrolamellar hepatocellular carcinoma. On review of original reports, DI had 82.6% sensitivity and 97.4% specificity for the diagnosis of FNH. On blind review, the sensitivity of DI for FNH diagnosis was 81.3% for MRI (13/16), and 53.3% for CT (8/15). In this cohort of children with liver masses and no comorbidities, a diagnosis of FNH by imaging was highly specific, and MRI was the most sensitive study for its diagnosis. Liver biopsy may be deferred in selected children if the DI, particularly MRI, is indicative of FNH.
    Liver international: official journal of the International Association for the Study of the Liver 06/2013; 34(2). DOI:10.1111/liv.12241 · 4.85 Impact Factor
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    ABSTRACT: Purpose: To assess the use of cuffed peripherally inserted central catheters (PICCs) compared with uncuffed PICCs in children with respect to their ability to provide access until the end of therapy. Materials and methods: A retrospective review of PICCs inserted between January 2007 and December 2008 was conducted. Data collected from electronic records included patient age, referring service, clinical diagnosis, inserting team (pediatric interventional radiologists or neonatal intensive care unit [NICU] nurse-led PICC team), insertion site, dates of insertion and removal, reasons for removal, and need for a new catheter insertion. A separate subset analysis of the NICU population was performed. Primary outcome measured was the ability of the PICCs to provide access until the end of therapy. Results: Cuffed PICCs (n = 1,201) were significantly more likely to provide access until the end of therapy than uncuffed PICCs (n = 303) (P = .0002). Catheter removal before reaching the end of therapy with requirement of placement of a new PICC occurred in 26% (n = 311) of cuffed PICCs and 38% (n = 114) of uncuffed PICCs. Uncuffed PICCs had a significantly higher incidence of infections per 1,000 catheter days (P = .023), malposition (P = .023), and thrombus formation (P = .022). In the NICU subset analysis, cuffed PICCs had a higher chance of reaching end of therapy, but this was not statistically significant. Conclusions: In this pediatric population, cuffed PICCs were more likely to provide access until the end of therapy. Cuffed PICCs were associated with lower rates of catheter infection, malposition, and thrombosis than uncuffed PICCs.
    Journal of vascular and interventional radiology: JVIR 05/2013; 24(9). DOI:10.1016/j.jvir.2013.03.003 · 2.41 Impact Factor
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    ABSTRACT: BACKGROUND: Analysis of small pulmonary nodules in children poses an important diagnostic and therapeutic challenge for clinicians. OBJECTIVE: To review our experience of lung tattooing with immediate video-assisted thoracoscopic resection (IVATR) performed as a single procedure in a hybrid room for technical difficulties, complications and diagnostic yield of the procedure. MATERIAL AND METHODS: Retrospective analysis of 31 children (16 boys, 15 girls) who underwent lung tattooing of various lesions from January 2001 to July 2011. Data were collected from the Interventional Radiology database, Electronic Patient Chart (EPC) and PACS. RESULTS: A total of 34 lesions were treated in 31 children. Tattooing was performed on lung lesions with median size 3 mm and median depth 2 mm from pleura. Technical success was 91.1% and diagnostic yield was 100%. In seven children, it was combined with other interventional radiologic procedures. The median procedure time for lung tattooing and IVATR was 197 min. CONCLUSION: Lung tattooing with IVATR as a single procedure in a hybrid room is safe and effective in children with several inherent advantages, including avoiding the need to move the child from the interventional radiology suite to the operating room.
    Pediatric Radiology 03/2013; 43(9). DOI:10.1007/s00247-013-2665-6 · 1.57 Impact Factor
  • Dimitri A Parra · Govind B Chavhan · Amer Shammas · Philip R John ·

    Canadian Association of Radiologists Journal 02/2013; 64(4). DOI:10.1016/j.carj.2012.12.002 · 0.52 Impact Factor
  • Arvind Shergill · Philip John · Joao G Amaral ·
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    ABSTRACT: Lymphatic malformations (LMs) are congenital lesions of the lymphatic system and consist of lymphatic channels and cystic spaces of varying sizes. Recent evidence has shown that LMs respond well to intralesional sclerotherapy. The purpose of this retrospective study is to evaluate the outcome and efficacy of using doxycycline in treating macrocystic, microcystic and combined macro- and microcystic LMs in a tertiary-care pediatric center. Fifty children (32 boys, 18 girls) underwent doxycycline sclerotherapy for treatment of LMs between January 2005 and October 2010. Demographics, imaging, doxycycline treatment details, complications and follow-up details were documented. The mean age at first treatment was 5.9 years (3 days-17.8 years), median 4.2 years. Cervicofacial (19/50 children) and truncal (16/50 children) locations were the most frequently affected. One hundred forty-six sclerotherapy sessions were performed in 50 children (mean 2.9/child). The mean doxycycline dose/kg body weight for 146 sessions was 15.3 mg/kg (0.6-85.7 mg/kg). Complications occurred in 4/146 procedures. Clinical follow-up showed excellent response in 14/16 children with macrocystic LMs, 21/27 children with combined LMs and 4/7 children with microcystic LMs. Doxycycline is a safe and effective sclerosant agent for treating LMs in children, with a low complication rate.
    Pediatric Radiology 05/2012; 42(9):1080-8. DOI:10.1007/s00247-012-2406-2 · 1.57 Impact Factor
  • P.L. Valentino · S.C. Ling · V.L. Ng · P. John · B.M. Kamath ·

    Journal of Hepatology 04/2012; 56:S547-S548. DOI:10.1016/S0168-8278(12)61407-X · 11.34 Impact Factor
  • Craig Gibson · Philip John · Joao Amaral ·
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    ABSTRACT: Gibson C, John P, Amaral J. A novel approach to endovascular treatment of severe hepatic vein stenoses following liver transplant in children. Pediatr Transplantation 2012. © 2012 John Wiley & Sons A/S. Abstract:  Hepatic vein stenoses are a rare but serious complication of liver transplants in children. Restoration of flow by radiological methods often provides a viable treatment option. This technique relies on the interventional radiologist's ability to advance a guide wire across the obstruction, thus allowing for balloon dilatation and other necessary interventions. Failure to cross the stenosis reduces graft survival and increases patient morbidity. We report two cases with tight hepatic vein stenosis where the guide wire could not be advanced in a conventional approach across the upper end of the stenosis. Utilizing prominent intrahepatic collateral vessels, the stenoses were able to be crossed, facilitating successful PTA with good clinical outcome.
    Pediatric Transplantation 03/2012; 16(7):E306-10. DOI:10.1111/j.1399-3046.2012.01675.x · 1.44 Impact Factor
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    ABSTRACT: To assess the effects of repeated placements of peripherally inserted central catheters (PICCs) on the venous system in children. Children who underwent successful first-time PICC placements between 2005 and 2007 were retrospectively evaluated. Patient demographics, procedural data, and complications were obtained from hospital databases. Data from subsequent PICC insertions were compared with those from previous PICC insertions. A generalized estimating equation was used with appropriate statistical tests for data analysis. PICCs were grouped into four groups: first PICCs (n = 1,274), second PICCs (n = 167), third PICCs (n = 52), and fourth to seventh PICCs (n = 32). Successive PICCs were associated with progressively increased difficulty of access compared with earlier PICCs, as demonstrated by significant increases in procedural duration (P = .01) and fluoroscopy time (P = .005). Increased complexity was also evident through significant increases in the percentages of cases that required venography/digital subtraction angiography (P <.0001), multiple attempts to gain venous access (P <.0001), and a switch to another limb for venous access (P <.0001) between subsequent and first PICCs. In addition, rates of procedural complications also increased for subsequent PICCs compared with first PICCs (P <.0001). Furthermore use of the most preferred vein for vascular access significantly decreased in subsequent versus first PICC insertions (P <.0001). Increased procedural complexity and complications were found with successive PICC insertions. These results confirm the need for a prospective study to directly assess the long-term effects of PICCs on venous patency.
    Journal of vascular and interventional radiology: JVIR 03/2012; 23(3):351-7. DOI:10.1016/j.jvir.2011.11.024 · 2.41 Impact Factor
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    ABSTRACT: Children with Pierre Robin sequence (PRS) have significant oropharyngeal abnormalities, with respiratory and feeding difficulties. Gastrostomy tubes (G-tube) provide a means for nutrition. To evaluate the safety and efficacy of percutaneous G-tube insertion in children with PRS. Of 120 children with PRS (1996-2009), 40 were referred for G-tube insertion; clinical details were reviewed in 37/40 children (18M, 19F) at three time periods: (1) pre-G-tube insertion, (2) at G-tube insertion, (3) at G-tube removal. Pre-G-tube: 32/37 were term infants; 5 were preterm; 16/37 children were ≤ 10th weight percentile. At G-tube insertion, mean age was 66 days, mean weight 4.4 kg (1.1-7.0 kg); 19 dropped ≥10 weight percentiles; 12 tolerated nil by mouth; 2/37 were intubated for the procedure. All G-tubes were successfully placed, with five minor technical issues. Early postprocedure, there were eight minor complications and two dislodgements (classified as major). At G-tube removal mean G-tube dwell time was 2 years, with an average of 3.6 maintenance procedures per child, approximately 3 tube changes/1,000 tube days. At G-tube removal, 76% had maintained or increased weight centiles. G-tubes in PRS provide a safe method for nutrition until children feed adequately by mouth.
    Pediatric Radiology 12/2011; 42(5):566-73. DOI:10.1007/s00247-011-2301-2 · 1.57 Impact Factor
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    ABSTRACT: Anterior mediastinal masses in children are clinically challenging, requiring prompt histological diagnosis. The purpose of this study was to review the experience with US-guided percutaneous core needle biopsy (PCNB) of anterior mediastinal masses in children, particularly with respect to safety and diagnostic accuracy. We retrospectively reviewed the clinical presentation, imaging, sedation approach, procedural details and pathology results of US-guided PCNB of mediastinal masses that occurred during an 8-year period (2001-2008). Complications were graded and pathology was categorized into four groups based on adequacy and diagnostic yield. 32 US-guided PCNBs were performed on 32 children, mean age 12 years (range 18 months to 17 years), mean weight 48 kg (range 11.5 to 109 kg, median 49 kg). A coaxial US-guided technique was used, with a mean of 8.2 passes and a mean 7.6 cores obtained (range 2-15). There were no major complications. The biopsies were adequate in volume and quality of specimens in 29/32, and 25/32 were diagnostic. PCNB was diagnostic in all cases of non-Hodgkin disease. Experience with anterior mediastinal masses suggests that US-guided PCNB can be considered a viable, safe and accurate method of reaching a diagnosis in the pediatric population.
    Pediatric Radiology 08/2011; 42(1):40-9. DOI:10.1007/s00247-011-2204-2 · 1.57 Impact Factor
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    ABSTRACT: High-flow hepatic vascular anomalies with arteriovenous shunting commonly manifest during the neonatal period with signs and symptoms of congestive heart failure, but to our knowledge, they have never been described in patients with hereditary hemorrhagic telangiectasia (HHT). We report here our experience with 3 patients with hepatic arteriovenous malformations (AVMs) who presented with symptoms of high-output congestive heart failure during the neonatal period and were subsequently diagnosed with HHT. Imaging showed large hypervascular lesions and multiple hepatic arteriovenous shunts that differentiated these lesions from liver hemangiomas. Transcatheter embolization was performed in all cases. One infant died of sepsis shortly after embolization; follow-up at the age of 2.5 years of the surviving infants revealed involution of the vascular lesions and no evidence of symptom recurrence. We conclude that severe symptoms related to hepatic AVMs in HHT can occur in the neonatal period and that HHT should therefore be included in the differential diagnosis of symptomatic neonatal hepatic vascular malformations. Imaging plays a key role in differentiating hepatic AVMs from hemangiomas, because the latter require additional pharmacologic treatments. Early transcatheter embolization seems to be effective, but long-term outcomes still need to be assessed.
    PEDIATRICS 06/2011; 127(6):e1615-20. DOI:10.1542/peds.2010-2366 · 5.47 Impact Factor
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    ABSTRACT: To report (1) our experience with botulinum toxin A injections into the salivary glands of pediatric patients with sialorrhea, (2) the clinical outcomes of these interventions, and (3) the associated complication rates. Retrospective cohort study. Urban pediatric hospital and pediatric rehabilitation center. Forty-five neurologically impaired children. Patients received botulinum toxin A intrasalivary injections between January 2004 and May 2008 at the Hospital for Sick Children in Toronto, Ontario, Canada. All patients received sedation or general anesthesia for their botulinum toxin A injections, which were performed using ultrasonographic guidance. Posttreatment assessments included the duration of effect, patient complications, saliva consistency, caregiver willingness to repeat the treatment, caregiver satisfaction with the treatment, and caregiver overall assessment of the child's posttreatment quality of life. Forty-five subjects received a total of 91 botulinum toxin A treatments. The mean (SD) duration of effect was 4.6 (5.2) months. Duration of effect (log transformed) was significantly negatively associated with saliva quantity (P = .02), and there was a positive association with both increasing age and female sex, although neither reached statistical significance (P = .08 for each). Seven of the 24 documented complications were major, according to the Society of Interventional Radiology Classification System for Complications by Outcome scale. Thirty-six of the caregivers reported that this treatment improved the child's quality of life (80%). Ultrasonographically guided botulinum toxin A injections into the salivary glands are safe and efficacious in the management of sialorrhea in children with neurologic disorders.
    Archives of otolaryngology--head & neck surgery 04/2011; 137(4):339-44. DOI:10.1001/archoto.2010.240 · 2.33 Impact Factor
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    ABSTRACT: Percutaneous biopsies of soft-tissue organs are frequently performed using US guidance. US permits visualization of blood flow on color Doppler imaging. To report the presence of color Doppler signal (positive color Doppler sign) along the biopsy tract after percutaneous needle biopsy of the liver and kidney as an indication of bleeding and to describe US-guided hemostasis. A case-control study of US-guided liver and kidney biopsies performed between January 2005 and September 2009 was undertaken. All pediatric patients with a positive color Doppler sign along the biopsy tract were included. Controls consisted of patients in whom no color Doppler sign was identified. Fifty-three cases with positive color Doppler sign were identified. One hundred and six matched controls were selected. The average compression time was 9.2 min in kidney and 8.4 min in liver cases. US-guided compression achieved cessation of the positive color Doppler sign in all cases. There was no significant difference between the mean pre- and post-procedure hemoglobin and platelet levels between kidney cases and controls (P=0.68 and P=0.63, respectively) and between liver cases and controls (P=0.45 and P=0.80). Color Doppler US can detect bleeding post percutaneous liver and kidney biopsies. US-guided compression is effective in obliterating the color Doppler signal and achieving appropriate hemostasis.
    Pediatric Radiology 10/2010; 41(3):362-8. DOI:10.1007/s00247-010-1848-7 · 1.57 Impact Factor
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    ABSTRACT: Juvenile idiopathic arthritis (JIA) has an incidence that ranges from 1 to 22 per 100,000 children worldwide, with involvement of the temporomandibular joint (TMJ) in 17-87% of patients. Intraarticular corticosteroid injections are beneficial in the local treatment of JIA and of other types of arthritis. To describe and assess the accuracy of an US-guided technique for visualization of needle placement within the TMJ in children. Between January 2000 and November 2007, 180 TMJ injections were performed during 116 encounters in 83 children with arthritis (71 girls, 12 boys; mean age 12.0 years). Access was obtained under sterile conditions using US guidance (linear 15-MHz or curvilinear 8-MHz transducers) in a coronal plane, and confirmed with CT. To minimize radiation, a limited focused CT protocol was developed. A bilateral injection was performed in 65 encounters (57%). Twenty-three children had repeat TMJ injections. All injections were performed using US guidance. CT confirmation was used in 127/180 TMJs (70%). In those confirmed with CT, the needle tip was intra-articular in 91% of cases. Triamcinolone hexacetonide was used in 92% of injections and triamcinolone acetonide in 8%. One major complication was encountered (skin atrophy at the injection site). In our experience, TMJ injections using sonographic guidance is a safe, effective and accurate procedure.
    Pediatric Radiology 03/2010; 40(9):1498-504. DOI:10.1007/s00247-010-1581-2 · 1.57 Impact Factor
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    ABSTRACT: Complex combined vascular malformations affecting extremities are an interesting group of vascular malformations because, in addition to the vascular channel anomalies present, they can be associated with other tissue changes and sometimes altered limb growth. At present, magnetic resonance imaging is the gold standard imaging tool to evaluate such complex conditions in children because of its inherent tissue specificity and vascular capabilities that enables characterization of tissues and the vascular channel anomalies both for diagnosis and management of the patient. A brief review of some of these conditions is presented, including Klippel-Trénaunay syndrome, Parkes Weber syndrome, extensive diffuse low-flow venous malformations, Bannayan-Riley-Ruvalcaba syndrome, cutis marmorata telangiectatica congenita, Maffucci's syndrome, and Gorham-Stout disease.
    Seminars in Musculoskeletal Radiology 10/2009; 13(3):255-76. DOI:10.1055/s-0029-1237692 · 1.09 Impact Factor
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    ABSTRACT: Vascular anomalies are vascular lesions noted at birth or that arise during the first months of life. The purpose of this article is to illustrate how vascular anomalies involve the extremities of infants and children. Cases illustrate the range of vascular anomalies as defined by the International Society for the Study of Vascular Anomalies. Both clinical and imaging features of extremity vascular anomalies are discussed. A comprehensive classification that uses a simple, universal, and common terminology is presented. Ultrasound and magnetic resonance imaging are noninvasive diagnostic tools that are widely used in pediatric practice, in particular to categorize many of these lesions, provide a diagnosis if there is clinical doubt, evaluate these lesions fully, and guide management and therapy.
    Seminars in Musculoskeletal Radiology 10/2009; 13(3):210-35. DOI:10.1055/s-0029-1237690 · 1.09 Impact Factor
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    ABSTRACT: We report a case of n-butyl-2-cyanoacrylate glue embolization of life-threatening lower gastrointestinal (LGI) hemorrhage in a 10-month-old boy. The child had a history of gastroschisis and short-bowel syndrome. Six months prior to the LGI bleed, he had undergone a serial transverse enteroplasty (STEP) to lengthen his intestine. To the best of our knowledge this is both the first report of successful glue embolization for LGI bleeding in a child and also the first report of severe hemorrhage after the STEP procedure.
    Pediatric Radiology 08/2009; 39(10):1098-101. DOI:10.1007/s00247-009-1328-0 · 1.57 Impact Factor
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    ABSTRACT: We report a case of penetration of the inferior vena cava (IVC) by all four primary struts of a Celect caval filter in a 17-year-old girl with Klippel-Trénaunay syndrome. The girl presented with acute lower abdominal and right leg pain 17 days after filter insertion. An abdominal radiograph demonstrated that the filter had moved caudally and that the primary struts had splayed considerably since insertion. Contrast-enhanced CT confirmed that all four primary struts had penetrated the IVC wall. There was a small amount of retroperitoneal hemorrhage. The surrounding vessels and viscera were intact. The filter was subsequently retrieved without complication.
    Pediatric Radiology 08/2009; 39(10):1110-3. DOI:10.1007/s00247-009-1340-4 · 1.57 Impact Factor

Publication Stats

290 Citations
89.17 Total Impact Points


  • 2006-2013
    • SickKids
      • Department of Diagnostic Imaging
      Toronto, Ontario, Canada
  • 2005-2013
    • University of Toronto
      • Hospital for Sick Children
      Toronto, Ontario, Canada