Safety of Periprocedural Antithrombotics during Pediatric Transplant Liver Biopsies.

The purpose of this study was to compare the adverse event (AE) rates of percutaneous pediatric transplant liver biopsies in patients receiving periprocedural antithrombotic agents with those in patients not receiving them. A 19-year retrospective single-center study of ultrasound-guided transplant liver biopsies was conducted. Patients who received aspirin for <5 days (n = 51) or heparin <4 hours (n = 15) before biopsy were separately grouped. AEs were reported using the Society of Interventional Radiology classification. In 276 biopsy samples from patients with a mean age of 6.75 years ± 5.80, the overall AE (P = .72) and moderate AE (P = .78) rates for control and antithrombotic groups were not significantly different. No severe AEs or deaths occurred. In conclusion, aspirin continuation during percutaneous pediatric transplant liver biopsies may be safe, but more studies are necessary to confirm the safety of periprocedural heparin.

Percutaneous treatment of symptomatic deep vein thrombosis in adolescents using large-bore thrombectomy systems.

BACKGROUND: While large-bore mechanical thrombectomy provides effective venous thrombus removal, often with avoidance of thrombolytics, literature surrounding the application of these devices in pediatric patients is sparse. OBJECTIVE: To report technical success and outcomes following large-bore thrombectomy systems in adolescent patients with deep venous thrombosis. MATERIALS AND METHODS: A retrospective review identified all patients less than 18 years of age undergoing mechanical venous thrombectomy at a single institution between 2018 and 2022. No patients were excluded. Technical success was defined as extraction of thrombus sufficient to restore unimpeded flow in affected segments. Clinical success was defined as resolution of presenting symptoms. RESULTS: Nine consecutive patients (6 females, 3 males; age range 15-17 years) underwent 10 thrombectomy procedures using ClotTriever (n=6; 60%), FlowTriever (n=2; 20%), or both (n=2; 20%). Chronicity of thrombus was categorized as acute (<2 weeks) in 6 (60%), subacute (2-6 weeks) in 1 (10%), and chronic (>6 weeks) in 3 (30%). Distribution of thrombus was lower extremity and/or inferior vena cava (IVC) in 9 (90%) and unilateral axillo-subclavian in 1 (10%). Technical success was achieved in 9 interventions (90%). Clinical success was achieved in 8 patients (88.9%). No patients received thrombolytics. There were no intraprocedural adverse events (AE). Minor complications (Society of Interventional Radiology mild adverse events) were observed in a delayed fashion following 2 interventions (20%). CONCLUSIONS: This preliminary experience demonstrated high rates of technical and clinical success with large-bore deep venous thrombectomy in adolescent patients across a range of thrombus chronicity and locations.

Intravascular US: Applications in Interventional Radiology.

Interventional radiology applications of intravascular US (IVUS) continue to expand, complementing intraprocedural angiography and providing a unique vantage from which to guide endovascular interventions. Vascular pathologic conditions become sonographically visualized rather than inferred from the planar appearance of the opacified vascular lumen. Perivascular targets become sonographically visualized rather than approximated on the basis of fluoroscopic landmarks. The authors introduce broad categories of IVUS catheters, namely radial and side-firing varieties, as well as prevailing options for each and their technical specifications. Common applications within interventional radiology are covered in a systems approach, including deep venous thrombosis, May-Thurner syndrome, nutcracker syndrome, transjugular intrahepatic portosystemic shunts, aortic interventions, peripheral arterial disease, and endovascular or perivascular biopsy. Discussions are accompanied by technical pearls from the authors, and summarized evidence where IVUS has been shown to reduce procedural time, intravascular contrast agent dose, radiation exposure, and morbidity in each space is presented. Finally, emerging applications and future directions are discussed. ©RSNA, 2022.

Intravascular ultrasound for endovascular precision in pediatrics.

Intravascular ultrasound (IVUS) is used as a diagnostic adjunct to angiography and has become a valuable diagnostic and interventional tool with a well-documented safety profile. The American College of Cardiology and the European Society of Cardiology have published guidelines regarding the use of IVUS in the setting of percutaneous coronary intervention. IVUS has gained popularity in the interventional radiology (IR) community in recent years; however, there are no consensus guidelines for utilization. Furthermore, IVUS remains an infrequently used modality in pediatric IR, likely because of unfamiliarity with the equipment and techniques, as well as concerns over the compatibility of these instruments with pediatric anatomy. IVUS can be safely used as a helpful and sometimes necessary tool for pediatric interventions in appropriately selected patients. The utility of IVUS for reducing both fluoroscopy time and contrast agent volume makes it particularly valuable in pediatric practice. This article presents an overview of both the rotational and phased-array IVUS types and an in-depth discussion on the most common applications of these techniques in the pediatric setting across multiple procedure categories.

Portomesenteric and portosystemic venous reconstructions in children using balloon-expandable endoprostheses.

BACKGROUND: Portomesenteric and portosystemic venous occlusive disease may lead to portomesenteric hypertension, variceal bleeding, ascites and hypersplenism. Data regarding endovascular reconstructive strategies in children, however, are limited. OBJECTIVE: To report technical success, outcome and patency of portomesenteric and portosystemic venous reconstruction using VIABAHN VBX balloon-expandable endoprostheses in pediatric patients. MATERIALS AND METHODS: Five pediatric patients (median age: 15 years, range: 4-18 years), including 3 (60%) boys and 2 (40%) girls, with portomesenteric or portosystemic venous occlusion or recurrent stenosis, underwent balloon-expandable stent graft reconstruction. Presenting symptoms included acute variceal bleeding, without (n = 2, 40%) or with (n = 1, 20%) splenomegaly, and transfusion-dependent chronic melena (n = 1, 20%). One patient was asymptomatic (n = 1, 20%). Preprocedural imaging included Doppler ultrasound and contrast-enhanced computed tomography (CT) in all patients. Initial imaging showed 4 (80%) occlusions and 1 (20%) recurrent stenosis greater than 50%. Technical aspects of the reconstructions, technical successes, clinical outcomes and adverse events were recorded. Technical success was defined as completion of stent graft reconstruction. Adverse events were categorized according to Society of Interventional Radiology criteria. Clinical success was defined as resolution of the presenting symptoms and/or prevention of portal hypertensive sequela. RESULTS: Venous reconstruction was technically successful in all five patients. Stent graft locations included the main portal vein in 2 (40%), the superior mesenteric vein in 1 (20%), autologous Meso-Rex shunt in 1 (20%) and splenocaval shunt in 1 (20%). Six stent grafts were placed (two stent grafts placed in a single patient). Stent grafts had a median diameter of 7 mm (range: 6-10 mm) and a median length of 59 mm (range: 19-79 mm). Median fluoroscopy time was 36.6 min (range: 13.4-95.8 min) and median air kerma was 301.0 mGy (range: 218.0-1,148.2 mGy). No adverse events occurred. Median clinical follow-up was 18 months (range: 6-29 months). Median imaging follow-up was 17 months (range: 2-29 months). Clinical success was achieved in all patients and maintained during the follow-up period. One patient required follow-up intervention with superior mesenteric vein side extension with a self-expanding bare metal stent due to perigraft stenosis detected on CT 3 months after stent placement. There were no stent graft occlusions. CONCLUSION: Portomesenteric and portosystemic venous reconstruction using balloon-expandable stent grafts in pediatric patients was feasible and clinically successful in this preliminary experience. Additional studies are warranted.

Evaluation and management of biliary complications after pediatric liver transplantation: pearls and pitfalls for percutaneous techniques.

In pediatric liver transplantation, bile duct complications occur with a greater incidence than vascular anastomotic dysfunction and represent a major source of morbidity and mortality. While surgical re-anastomosis can reduce the need for retransplantation, interventional radiology offers minimally invasive and graft-saving therapies. The combination of small patient size and prevailing Roux-en-Y biliary enteric anastomotic techniques makes endoscopic retrograde cholangiopancreatography difficult if not impossible. Expertise in percutaneous management is therefore imperative. This article describes post-surgical anatomy, pathophysiology and noninvasive imaging of biliary complications. We review percutaneous techniques, focusing heavily on biliary access and interventions for reduced liver grafts. Subsequently we review the results and adverse events of these procedures and describe conditions that masquerade as biliary obstruction.

Combined ultrasound and fluoroscopy guided tunneled external lumbar drain placement in children.

External lumbar drain placement has been shown to be an efficacious and safe approach to managing various forms of intracranial hypertension in adult patients and children. The use of ultrasound guidance for lumbar punctures in young patients has been described however, but the modality is not routinely used for the placement of tunneled lumbar drains. In this report, two cases are presented that detail experience using ultrasound guidance for tunneled lumbar drains in children.

Time-Driven Cost Analysis of Noncuffed Venous Catheter Placement in Infants: Bedside versus IR Suite.

PURPOSE: To compare the direct bundled costs of interventional radiology (IR) suite versus bedside placement of noncuffed central venous catheters in infants. METHODS: A single-center retrospective review was performed of all noncuffed upper extremity (peripherally inserted central venous catheter [PICC]) and tunneled femoral (tunneled femoral central venous catheter [TCVC]) catheters placed in infants between January 1, 2018, and December 31, 2018. Propensity score matching was performed adjusting for age, birth weight, procedure weight, and catheter days. Process maps for each procedure were created based on location and sedation type. Technical success and complications were recorded for each placement. The total direct bundled cost for each catheter placement was calculated by summing the procedure and complication costs. RESULTS: A total of 142 procedures were performed on 126 matched patients with a technical success of 96% at the bedside and 100% in the IR suite (P = .08). The complication rates did not significantly differ between the 2 groups (P = .51). The total direct bundled costs for catheter placement were $1421.3 ± 2213.2 at the bedside and $2256.8 ± 3264.7 in the IR suite (P = .001). CONCLUSIONS: The bundled cost of bedside femoral catheter placement is significantly less than that of fluoroscopic TCVC and PICC placement performed in the IR suite, mainly related to differences in sedation costs.

Ultrasound Evaluation of Pediatric Slow-Flow Vascular Malformations: Practical Diagnostic Reporting to Guide Interventional Management.

OBJECTIVE. This article reviews the ultrasound characteristics of pediatric slow-flow vascular malformations and underscores findings that significantly impact diagnosis and treatment. Key imaging features are discussed including lesion size, malformation location, morphology, and mimics. CONCLUSION. Ultrasound findings affect the management of slow-flow vascular malformations and should be emphasized in lesion diagnosis. Superficial, focal lesions with well-defined margins are ideal for ultrasound evaluation.

Line days as a determinant of central line-associated bloodstream infections in pediatric patients with tunneled femoral peripherally inserted central catheters.

BACKGROUND: Ultrasound (US)-guided tunneled femoral peripherally inserted central catheters (PICCs) are a safe central venous access option in infants and neonates. Studies have shown, however, that femoral central venous access has the potential for high central line-associated bloodstream infection (CLABSI) rates with a significant increase in risk around line day 30, though no studies have evaluated these risks exclusively for tunneled femoral PICCs. OBJECTIVE: The primary purpose of this study was to evaluate the relationship between line duration and the risk of CLABSI in tunneled femoral PICCs in children. MATERIALS AND METHODS: Four hundred forty-five patients (196 females, 249 males; median age: 49.4 days; median weight: 3.7 kg) who underwent 573 tunneled femoral PICC placements or exchanges from Jan. 1, 2017, to Jan. 31, 2020, were included in the study. All tunneled femoral PICCs were placed using US technique and catheter specifications, including catheter size (French) and length (cm), were retrieved from the electronic medical record. The location of the PICC placement, the number of lumens, the laterality of placement, and the patient's age and weight were also recorded. Only non-mucosal barrier injury CLABSIs, according to the Centers for Disease Control and Prevention (CDC) definitions, were counted as CLABSI for this study. The number of central line days until a CLABSI event was analyzed with an accelerated failure time model using the exponential, Weibull, and log-normal distributions to determine the probability of a CLABSI over time, taking into consideration the recorded covariates. RESULTS: Tunneled femoral PICC placements accounted for 14,855 line days, during which 20 non-mucosal barrier injury CLABSIs (CLABSI rate of 1.35 per 1,000 line days) occurred during the study period. The highest CLABSI rate occurred in PICCs placed in the neonatal intensive care unit (NICU) at 2.01 per 1,000 line days and the lowest occurred in PICCs placed in interventional radiology at 0.26 per 1,000 line days. Overall, PICCs placed outside of interventional radiology had a CLABSI rate of 1.72 per 1,000 line days. The CLABSI rate during the first 30 days a line was in situ was lower than the rate after 30 days (0.51 per 1,000 line days vs. 3.06 per 1,000 line days, respectively). Statistical modeling and hazard estimation using the Akaike information criterion corrected for small sample size (AICc)-average of log-normal, Weibull and exponential distributions demonstrate the daily risk of CLABSI rapidly increases from day 1 to day 30, with the risk remaining high for the duration of line days. CONCLUSION: While tunneled femoral PICCs are a relatively safe and effective central venous access alternative, the rate of CLABSI appears to rapidly increase with increasing line days until around day 30 and then remains high thereafter.

Spinal ultrasound after failed landmarked-based lumbar puncture: a single institutional experience.

BACKGROUND: The safety and efficacy of US-guided lumbar puncture in children has been described. In the pediatric setting, children are frequently referred to interventional radiology only after a failed landmark-based attempt. Routine pre-procedure US in these children is useful to determine a safe level for subarachnoid access and to optimize success. OBJECTIVE: To determine whether pre-procedure US improves technical success and safety of US-guided lumbar puncture. MATERIALS AND METHODS: We included 47 children. Inclusion criteria were urgent US-guided lumbar puncture in pediatric patients <18 years old. Exclusion criteria were non-urgent lumbar punctures, children referred without an antecedent landmark-based attempt, lumbar punctures performed with fluoroscopic guidance, and procedures performed prior to introducing the diagnostic approach in 2017. We did not evaluate data pertaining to successful landmark-based lumbar punctures performed without subsequent need for additional attempts. We recorded technical successes, adverse events and relevant abnormalities identified on pre-procedural US. RESULTS: Thirty-six US-guided lumbar punctures were performed with 100% technical success. Eleven children referred to interventional radiology did not undergo lumbar puncture because of unfavorable US findings or interval clinical improvement obviating the need for lumbar puncture. Thirty-six children underwent US evaluation of the thecal sac prior to potential intervention. Of these 36 with pre-procedural US studies, 12 demonstrated paucity of cerebrospinal fluid and 14 demonstrated an epidural hematoma. Fifteen children who underwent lumbar puncture had a "traumatic tap," classified as a mild adverse event. No moderate or severe adverse events were recorded. CONCLUSION: Limited spinal US following failed landmark-based lumbar punctures frequently identifies procedure-related complications and can augment patient selection for future image-guided lumbar punctures.

Confirmatory radiographs have limited utility following ultrasound-guided tunneled femoral central venous catheter placements by interventional radiology.

BACKGROUND: Ultrasonography may reliably visualize both appropriately positioned and malpositioned femoral-approach catheter tips. Radiography may be used to confirm catheter tip position after placement, but its utility following intraprocedural ultrasound (US) catheter tip verification is unclear. OBJECTIVES: To report the utility of confirmatory radiographs after US-guided tunneled femoral central venous catheter (CVC) placements by interventional radiology in pediatric patients. MATERIALS AND METHODS: A total of 484 pediatric patients underwent bedside US-guided tunneled femoral CVC placements in an intensive care setting at a single tertiary children's hospital between Jan. 1, 2016, and April 20, 2020. Technical success, adverse events, post-procedure radiographic practices and inter-modality catheter tip concordance were recorded. All radiographs were performed within 12 h of catheter placement. RESULTS: The mean patient age was 175±508 days (range: 1 day to 19 years), including 257 (53.1%) males and 227 (46.9%) females. Of the 484 attempted placements, 472 (97.5%) were primary placements. Four hundred eighty-one (99.4%) placements were technically successful. There were three (0.6%) technical failures due to previously undiagnosed iliofemoral venous occlusive disease. Five (1.0%) adverse events occurred. Radiographs were obtained within 12 h of CVC placement in 171 (35.3%) patients, in 120 (70.2%) of whom the indication was recent catheter placement. All 171 (100%) post-placement radiographs showed catheter tip location concordance with the intra-procedural US. In one (0.2%) patient, in whom there was nonvisualization of a guidewire and clinical concern for malposition during US-guided placement, post-procedure radiographs, coupled with multiplanar venography, demonstrated inadvertent paravertebral venous plexus catheter placement. CONCLUSION: The concordance between intra-procedural US and confirmatory post-procedure radiographs of CVC placements by interventional radiology obviates the need for routine radiographs. Radiographs may be obtained in instances of proceduralist uncertainty or clinical concern.

Transjugular intrahepatic portosystemic shunt creation may be associated with hyperplastic hepatic nodular lesions in the long term: an analysis of 18 pediatric and young adult patients.

BACKGROUND: Retrospective studies have demonstrated the efficacy and safety of pediatric and adolescent transjugular intrahepatic portosystemic shunt (TIPS), but long-term outcomes warrant further investigation. OBJECTIVE: To report on the development of hyperplastic hepatic nodular lesion development in children and young adults (<21 years) with TIPS patency >3 years. MATERIALS AND METHODS: Eighteen children and young adults, including 10 (55.6%) females and 8 (44.4%) males, underwent TIPS creation with >3 years' patency and follow-up evaluation at a tertiary children's hospital. The mean age at the time of TIPS creation was 12.5±5.1 years (range: 1.5-20.0 years). The mean model for end-stage liver disease (MELD) at the time of TIPS creation was 8.1±1.6 (range: 6-11). Indications for TIPS creation included acute variceal bleeding (8/18, 44.4%), primary (1/18, 5.6%) or secondary (7/18, 38.9%) prevention of varices, portal vein thrombosis (1/18, 5.6%), and splenic sequestration (1/18, 5.6%). Technical successes, intra-procedural parameters, hemodynamic and clinical successes, TIPS patencies, adverse events, imaging evaluations, and follow-ups were recorded. RESULTS: All (100%) TIPS placements were successful; however, a direct intrahepatic portosystemic shunt was created in one (5.6%) patient. Mean reduction of the portosystemic shunt gradient was 9.1±3.3 mmHg (range: 4-16 mmHg). Seventeen (94.4%) patients demonstrated clinical success with resolution of their initial clinical indication for TIPS placement. The 3-year TIPS primary, primary-assisted, and secondary patencies were 83.3% (15/18), 94.4% (17/18), and 100% (18/18), respectively. Two (11.1%) patients developed mild, medically controlled hepatic encephalopathy. One (5.6%) patient developed hepatopulmonary syndrome. Nine (50%) patients developed single or multiple hepatic nodules at a mean imaging surveillance time after TIPS of 4.4±3.0 years (range: 1.5-10.2 years). Six (33.3%) patients developed nodules >1 cm with imaging features most consistent with focal nodular hyperplasia or focal nodular hyperplasia-like nodules. The mean follow-up duration was 5.7±2.9 years (range: 3.0-13.1 years). CONCLUSION: Long-term (>3 years) portosystemic shunting via TIPS is associated with the development of hepatic nodular lesions in children. Consequently, children with TIPS may need gray-scale assessment of hepatic parenchyma as part of routine ultrasound exams and extended imaging surveillance until more is understood regarding the natural history of induced nodularity.

Radiation dose reduction during intra-arterial chemotherapy for retinoblastoma: a retrospective analysis of 96 consecutive pediatric interventions using five distinct protocols.

BACKGROUND: Intra-arterial chemotherapy (IAC) represents a mainstay of retinoblastoma treatment in children. Patients with retinoblastoma are uniquely at risk for secondary malignancies and are sensitive to the ionizing effects of radiation. OBJECTIVE: To retrospectively review a single institution's experience with IAC for retinoblastoma and the effect of variable intra-procedural imaging techniques on radiation exposure. MATERIALS AND METHODS: Twenty-four consecutive patients, with a mean age of 30.8±16.3 months (range: 3.2-83.4 months), undergoing IAC for retinoblastoma between May 2014 and May 2020 (72 months) were included. No patients were excluded. The primary outcome was radiation exposure and secondary outcomes included technical success and procedural adverse events. Technical success was defined as catheterization of the ophthalmic or meningolacrimal artery and complete delivery of chemotherapy. Each procedure was retrospectively reviewed and categorized as one of five imaging protocol types. Protocol types were characterized by uniplanar versus multiplanar imaging and digital subtraction angiographic versus roadmap angiographic techniques. Radiation exposure, protocol utilization, the association of protocol and radiation exposure were assessed. RESULTS: During 96 consecutive interventions, 109 ocular treatments were performed. Thirteen of the 96 (15.5%) treatments were bilateral. Ocular technical success was 106 of 109 (97.2%). All three treatment failures were successfully repeated within a week. Mean fluoroscopy time was 6.4±6.2 min (range: 0.7-31.1 min). Mean air kerma was 36.2±52.2 mGy (range: 1.4-215.0 mGy). There were two major (1.8%) complications and four (3.7%) minor complications. Of the 96 procedures, 10 (10.4%), 9 (9.4%), 13 (13.5%), 28 (29.2%) and 36 (37.5%) were performed using protocol types A, B, C, D and E, respectively. For protocol type A, mean fluoroscopy time was 10.3±6.8 min (range: 3.0-25.4 min) and mean air kerma was 118.2±61.2 mGy (range: 24.5-167.3 mGy). For protocol type E, mean fluoroscopy time was 3.1±3.2 min (range: 0.7-15.1 min) and mean air kerma was 5.4±4.2 mGy (range: 1.4-19.5 mGy). Fluoroscopy time and air kerma decreased over time, corresponding to the reduced use of multiplanar imaging and digital subtraction angiography. In the first quartile (procedures 1-24), 8 (33.3%), 7 (29.2%), 2 (8.3%), 6 (25.0%) and 1 (4.2%) were performed using protocol types A, B, C, D and E, respectively. Mean fluoroscopy time was 10.5±8.2 min (range: 2.4-28.1 min) and mean air kerma was 84.2±71.6 mGy (range: 12.8-215.0 mGy). In the final quartile (procedures 73-96), 24 (100%) procedures were performed using protocol type E. Mean fluoroscopy time was 3.5±4.0 min (range: 0.7-15.1 min) and mean air kerma was 5.0±4.3 mGy (range: 1.4-18.0 mGy), representing 66.7% and 94.1% reductions from the first quartile, respectively. Technical success in the second half of the experience was 100%. CONCLUSION: Sequence elimination, consolidation from biplane imaging to lateral-only imaging, and replacing digital subtraction with roadmap angiography dramatically reduced radiation exposure during IAC for retinoblastoma without adversely affecting technical success or safety.

Burnout among Interventional Radiologists.

PURPOSE: To characterize burnout, as defined by high emotional exhaustion (EE) or depersonalization (DP), among interventional radiologists using a validated assessment tool. MATERIALS AND METHODS: An anonymous 34-question survey was distributed to interventional radiologists. The survey consisted of demographic and practice environment questions and the 22-item Maslach Burnout Inventory-Human Services Survey (MBI). Interventional radiologists with high scores on EE (≥ 27) or DP (≥ 10) MBI subscales were considered to have a manifestation of career burnout. RESULTS: Beginning on January 7, 2019, 339 surveys were completed over 31 days. Of respondents, 263 (77.6%) identified as male, 75 (22.1%) identified as female, and 1 (0.3%) identified as trans-male. The respondents were interventional radiology attending physicians (298; 87.9%), fellows (20; 5.9%), and residents (21; 6.2%) practicing at academic (136; 40.1%), private (145; 42.8%), and hybrid (58; 17.1%) centers. Respondents worked < 40 hours (15; 4.4%), 40-60 hours (225; 66.4%), 60-80 hours (81; 23.9%), and > 80 hours (18; 5.3%) per week. Mean MBI scores for EE, DP, and personal achievement were 30.0 ± 13.0, 10.6 ± 6.9, and 39.6 ± 6.6. Burnout was present in 244 (71.9%) participants. Identifying as female (odds ratio 2.4; P = .009) and working > 80 hours per week (odds ratio 7.0; P = .030) were significantly associated with burnout. CONCLUSIONS: Burnout is prevalent among interventional radiologists. Identifying as female and working > 80 hours per week were strongly associated with burnout.

Intrahepatic veno-venous collateralization and misrepresentative hepatic venous pressure gradients in children.

BACKGROUND: Accurate and reproducible means of measuring the portosystemic gradient are essential for risk stratification and treatment of portal hypertension. OBJECTIVE: To report the reliability of hepatic venous pressure gradients in children with intrahepatic veno-venous collateralization. MATERIALS AND METHODS: Between January 2012 and December 2019 (96 months), 39 patients with native livers underwent wedge hepatic venography and hepatic venous pressure gradient measurements at a tertiary pediatric center. All archived images were reviewed for balloon isolation of the hepatic vein and hepatic vein-to-hepatic vein (HV-HV) collaterals. HV-HV collaterals were categorized as present on the basis of non-catheterized segmental venous opacification despite appropriate balloon isolation. Hepatic venous pressure gradient was defined as the difference of wedge and free hepatic venous pressures. Wedge portosystemic gradient was defined as the difference between wedge hepatic venous pressure and right atrial (RA) pressures. For patients subsequently undergoing portal venous catheterization, portosystemic gradient was defined as the difference between main portal vein and RA pressures. RESULTS: Thirteen of 39 (33.3%) patients demonstrated HV-HV collaterals on wedge hepatic venography. The mean hepatic venous pressure gradient was 5.2±3.8 mmHg (range: 0-15 mmHg). The mean hepatic venous pressure gradient was 3.6±2.6 mmHg (range: 0-9 mmHg) in the presence of HV-HV collaterals and 5.9±4.2 mmHg (range: 1-15 mmHg) in the absence of HV-HV collaterals (P=0.043). Twelve (30.8%) patients were found to have varices: 10 gastroesophageal, 1 rectal and 1 stomal. The mean hepatic venous pressure gradient in patients with varices was 5.4±47 mmHg (range: 0-15 mmHg). For patients with varices, mean hepatic venous pressure gradient was 3.0±2.7 mmHg (range: 0-9 mmHg) in the presence of HV-HV collaterals and 10.3±4.1 mmHg (range: 5-15 mmHg) in the absence of HV-HV collaterals (P=0.004). Four (10.3%) patients had extrahepatic portal vein occlusion: 3 with cavernous transformation and 1 with type Ib Abernethy malformation. All patients with extrahepatic portal vein occlusion demonstrated HV-HV collaterals compared with 8 of 35 (22.9%) patients without extrahepatic portal vein occlusion (P=0.002). Four of 39 (10.3%) patients underwent direct portal pressure measurements: 3 via transhepatic and 1 via trans-splenic portal access. All had demonstrated HV-HV collaterals on wedged imaging. One had extrahepatic portal vein occlusion. The mean time between wedge portosystemic gradient and portosystemic gradient measurement was 3.75 days (range: 0-8 days). The mean wedge portosystemic gradient was 4.5±3.1 mmHg (range: 2-9 mmHg) and the mean portosystemic gradient was 14.5±3.7 mmHg (range: 12-20 mmHg) (P=0.006). CONCLUSION: HV-HV collateralization is frequently observed in children undergoing wedged portal venography and leads to misrepresentative hepatic venous pressure gradients. All patients undergoing hepatic venous pressure gradient measurement should have wedged venography to identify HV-HV collaterals and to qualify measured pressures. Additional techniques to obtain representative pressures in the presence of HV-HV collaterals warrant further investigation.

Pressure gradients, laboratory changes, and outcomes with transjugular intrahepatic portosystemic shunts in pediatric portal hypertension.

INTRODUCTION: Indications for TIPS are well described in adults and involve complications of PHTN. Complications from PHTN are associated with PSG of > 12 mm Hg in adults. It is unclear if these parameters apply to children with PHTN. OBJECTIVE: To assess whether adult criteria for TIPS placement can be utilized in children, describe laboratory changes over time, and report outcomes. METHODS: We performed a retrospective review of 34 pediatric patients who underwent TIPS, examining indications, radiology, PSG reductions, laboratory changes, and outcomes. RESULTS: Most patients had PHTN due to parenchymal liver disease including congenital hepatic fibrosis (n = 5), biliary atresia (n = 5), cystic fibrosis-related liver disease (n = 3) and cavernous transformation of the portal vein (n = 6). Indications for TIPS included variceal bleeding, recurrent ascites, and maintenance of portal vein flow following thrombolysis. Variceal bleeding was observed in six children with PSG < 12 mm Hg. Minor complications occurred in eight subjects. Continued bleeding occurred in one patient. Six patients were successfully bridged to transplantation, and three patients died secondary to end-stage disease. Standard laboratory tests stabilized after TIPS placement and hematocrit increased. CONCLUSION: TIPS placement in pediatric patients was performed for complications of PHTN. Unlike adult series, a substantial proportion of our cases treated extrahepatic PHTN from cavernous transformation of the portal vein. Children presented with sequelae of PHTN with PSG below 12 mm Hg, below the adult standard. We found TIPS in pediatrics to be safe and effective with laboratory stabilization and improvement in hematocrit.

Benefits and risks of protocol biopsies in pediatric renal transplantation.

Protocol biopsies are defined as sampling of allograft tissue at predetermined times regardless of function. This procedure can be justified due to the lack of non-invasive methods to reliably diagnose rejection (acute or subclinical). Changes in creatinine are not seen with subclinical rejection or early acute rejection and do not always correlate with efficacy of treatment. Parents and providers are still hesitant to pursue protocol biopsy due to the potential complications and lack of definitive evidence of a benefit from doing this procedure. Importantly, the rate of transplant renal biopsy complications requiring additional intervention is low. It is unclear if detection and treatment of subclinical rejection detected on protocol biopsy will lead to improved graft survival. Our goal is to review the literature on this topic and share some of the experience in our center. Definition, indications, and complications of diagnostic transplant renal biopsies are not included in this review.

Endovascular treatment of surgical mesoportal and portosystemic shunt dysfunction in pediatric patients.

BACKGROUND: Published data describing the endovascular treatment of dysfunctional mesoportal and portosystemic shunts in the pediatric population are limited. OBJECTIVE: We sought to describe the treatment and follow-up of such shunts managed by interventional radiology at a single pediatric hospital. We hypothesized that stenotic and occluded pediatric portosystemic and mesoportal shunts can be maintained patent by interventional radiology in the moderate term. MATERIALS AND METHODS: We conducted a single-center retrospective study at a tertiary pediatric hospital. We included children with surgical mesoportal (meso-Rex) or portosystemic (mesocaval, splenorenal or splenocaval) shunts treated with attempted angioplasty or stenting from 2010 to 2018. Technical success was defined as catheterization and intervention upon the shunt with venographic evidence of flow improvement. The primary outcome variables were shunt patency at 1 month, 6 months, 12 months and 24 months post-procedure and freedom from reintervention. RESULTS: Twenty pediatric patients (11 boys, 9 girls; mean age 8.25 years, range 1.3-17 years) met inclusion criteria. Fifty-two interventions (primary and reintervention) on 13 splenorenal, 3 meso-Rex, 2 mesocaval and 2 splenocaval shunts were performed because of evidence of shunt failure, including gastrointestinal bleeding, hypersplenism, or radiographic evidence of a flow defect. The 11 stenotic shunts were treated with 100% technical success, while the remaining 9 occluded shunts were treated with 66.7% technical success. The mean number of reinterventions was 1.9 (standard deviation [SD] = 3.1) per child, which did not differ between stenotic and occluded shunts (P=0.24). Primary patency at 1-month, 6-month, 12-month and 24-months follow-up visits was 17/17 (100%), 10/16 (62.5%), 7/15 (46.7%) and 4/10 (40%), respectively. However, 100% of shunts were either primary patent or primary-assisted patent by endovascular reintervention. There were no cases of shunt occlusion following initial technical success. Finally, the median freedom from reintervention duration was 387 days (SD=821 days). CONCLUSION: Dysfunctional portosystemic surgical shunts are effectively managed by endovascular methods. While many shunts require reintervention, combined primary patency and assisted primary patency rates are excellent.

Cone-beam computed tomography guidance with navigational overlay for percutaneous lung nodule biopsy.

BACKGROUND: Cone-beam CT is increasingly used in pediatric interventional radiology procedures. However, the feasibility or safety of using this mode of imaging guidance for percutaneous lung nodule biopsy in children has not been assessed. OBJECTIVE: To retrospectively evaluate safety and diagnostic accuracy of percutaneous lung nodule biopsy in people treated at a pediatric hospital using cone-beam CT with navigational overlay. MATERIALS AND METHODS: Thirty-six consecutive patients from two large tertiary-care children's hospitals with lung nodules of 48 mm or smaller underwent percutaneous lung nodule biopsy using cone-beam CT with navigational overlay. We evaluated patient demographics, pre- and post-biopsy diagnoses, number of biopsy passes, complications, radiation exposure and technical success. RESULTS: Percutaneous lung nodule biopsy was performed for 37 nodules in 36 patients (23 males, 13 females, median age 15.5 years, range 8 months to 23 years). One patient underwent biopsy of two nodules at a single procedure. Median patient weight was 55 kg (range 8-97 kg). Pre-biopsy diagnoses included metastatic sarcoma or other solid tumor (n=11), leukemia/lymphoma (n=13), infection (n=10), chronic granulomatous disease (n=2) and post-transplant lymphoproliferative disorder (PTLD; n=1). Mean number of passes was 5 (range 2-15). Mean pre-procedure international normalized ratio (INR) was 1.1 and platelet count 193 × 109/L. Diagnostic specimens were obtained in 32 of 36 patients (89%). Thirteen complications were encountered in 12 patients (33% of cohort), including 9 pneumothoraces (4 requiring chest tubes); 1 hemothorax, which required a chest tube; and 3 self-limited pulmonary hemorrhages. Mean and median radiation doses were as follows: fluoroscopy time 3 min and 2.4 min, dose-area product (DAP) (recorded in 31 patients) 23,402 Gy·cm2 and 12,453 Gy·cm2, and air kerma 88 mGy and 58 mGy. CONCLUSION: Percutaneous lung nodule needle biopsy can be performed accurately using cone-beam CT with navigational overlay.