Fostering research in pediatric interventional radiology: needs assessment and suggestions for support.

BACKGROUND: Due to the rarity of pediatric diseases, collaborative research is the key to maximizing the impact of research studies. A research needs assessment survey was created to support initiatives to foster pediatric interventional radiology research. OBJECTIVE: To assess the status of pediatric interventional radiology research, identify perceived barriers, obtain community input on areas of research/education/support, and create metrics for evaluating changes/responses to programmatic initiatives. MATERIALS AND METHODS: A survey link was sent to approximately 275 members of the Society for Pediatric Interventional Radiology (SPIR) between May and October 2020. Data was collected using a web-based interface. Data collected included practice setting, clinical role, research experience, research barriers, and suggestions for future initiatives. RESULTS: Fifty-nine surveys were analyzed with a staff physician survey response rate of 28% (56/198). A wide range of practice sizes from 15 countries were represented. Respondents were predominantly staff physicians (95%; 56/59) with an average of 11 years (range: 1-25 years) of clinical experience working at academic or freestanding children's hospitals. A total of 100% (59/59) had research experience, and 70% (41/58) had published research with a mean of 30 peer-reviewed publications (range: 1-200). For job security, 56% (33/59) of respondents were expected or required to publish, but only 19% (11/58) had research support staff, and 42% (25/59) had protected research time, but of those, 36% (9/25) got the time "sometimes or never." Lack of support staff, established collaborative processes, and education were identified as top barriers to performing research. CONCLUSIONS: The needs assessment survey demonstrated active research output despite several identified barriers. There is a widespread interest within the pediatric interventional radiology community for collaborative research.

Is There Really No Kit for Kids? Quantification of Manufacturer Recommendations Regarding Paediatric Use For High-Volume IR Devices.

AIMS: The development of paediatric specific devices appears to lag behind advancements in our specialty. Children could therefore be limited in the number of procedures available to them unless we continue to use and modify adult devices 'off-label'. This study quantifies the proportion of IR devices in which paediatric use is indicated by the manufacturer. MATERIALS & METHODS: Cross-sectional analysis of device instructions for use (IFU), assessing inclusion of children was performed. Vascular access, biopsy, drainage, and enteral feeding devices, from 28 companies who sponsored BSIR, CIRSE and SIR (2019-2020) as determined by the meeting websites, were included. Devices for which the IFU was not available were excluded. RESULTS: 190 (106 vascular access, 40 biopsy, 39 drainage and 5 feeding) devices with IFU's from 18 medical device manufacturers were assessed. 49/190 (26%) IFU's referenced children. 6/190 (3%) explicitly stated the device could be used in children and 1/190 (0.5%) explicitly stated the device was not for use in children. 55/190 (29%) implied they could be used in children through caution notes. The most common caution was a reference to the size of the device that could be accommodated in a child (26/190, 14%). CONCLUSIONS: This data identifies an unmet need for paediatric IR devices and could be used to support the future development of devices intended for the children we treat. There is potentially a larger proportion (29%) of devices suitable for paediatric use, but which lack manufacturer explicit support. LEVEL OF EVIDENCE: Level 2c, Cross-Sectional study.

Diagnostic yield and safety of ultrasound-guided percutaneous testicular biopsies in children.

BACKGROUND: Traditionally, testicular biopsy is performed using an open surgical approach. Ultrasound-guided percutaneous biopsy is a less invasive alternative and can be performed in children. OBJECTIVE: The aim of this study is to report our technique and to assess the diagnostic accuracy and safety of ultrasound-guided percutaneous biopsy of testicular masses in children. MATERIALS AND METHODS: This is a 16-year retrospective review of ultrasound-guided percutaneous testicular biopsies at a single pediatric hospital. RESULTS: We performed nine ultrasound-guided testicular biopsies in 9 patients (median age: 3 years, range: 4 months-11 years; median weight: 20.9 kg, range: 8.4-35 kg; median volume of testicular lesion biopsied: 4.4 mL, range: 1.2-17 mL). A percutaneous co-axial technique was used for 5/9 biopsies with absorbable gelatin sponge tract embolization performed in 4 of those biopsies. A non-co-axial technique was used in 4/9 biopsies. A median of three cores, range 2-6, were obtained. The diagnostic yield was 89% with one biopsy yielding material suggestive of, but insufficient for, a definitive diagnosis. The most common histological diagnosis was leukemic infiltration, occurring in 6/9 biopsies. Of the remaining three biopsies, one biopsy was suggestive of, but not confirmatory for, juvenile granulosa cell tumor and two biopsies confirmed normal testicular tissue; the long-term follow-up of which demonstrated normal growth and no lasting damage. There was one (clinically insignificant) complication out of nine biopsies (11%, 95% confidence interval 0-44%): a mild, self-resolving scrotal hematoma. CONCLUSION: Ultrasound-guided testicular biopsy can be performed safely in children as an alternative to open surgical biopsy, with a high diagnostic yield and low complication rate.

Evidence of Chemoresponsiveness in Unresectable Metastatic Angiomatoid Fibrous Histiocytoma.

Angiomatoid fibrous histiocytoma (AFH) is a soft tissue neoplasm of intermediate biological potential. Typically a slow-growing tumor, it can recur locally. Rarely, it manifests as a soft tissue sarcoma capable of metastasis. When metastases are nonamenable to local therapy, it is believed uniformly fatal. We present 3 patients with metastatic AFH who demonstrated a sustained response to chemotherapy; including one who achieved complete remission with cryoablation. These cases reinforce the potential value of chemotherapy in some patients with unresectable metastatic AFH and provide the first case in the literature of cryoablation in AFH.

Presentation, treatment, and outcome of renovascular hypertension below 2 years of age.

Renovascular hypertension in most cases requires endovascular treatment and/or surgery. This is technically much more difficult in small children and there is very limited published knowledge in this age group. We here present treatment and outcome of young children with renovascular hypertension at our institution. Children below 2 years of age, with renovascular hypertension between January 1998 and March 2020 were retrospectively reviewed. Demographics and treatment modalities were noted. Primary outcome was blood pressure within a week after the procedures and at last available visit. Sixty-six angiographies were performed in 34 patients. Median age at time of first angiography was 1.03 (interquartile range (IQR) 0.4-1.4) years and systolic blood pressure at presentation 130 (IQR 130-150) mm Hg. Thirty-eight percent (13/34) of children were incidentally diagnosed and 18% (6/34) presented with heart failure. Twenty-six (76%) children had main renal artery stenosis and 17 (50%) mid-aortic syndrome. Seventeen (50%) children showed intrarenal, six (18%) mesenteric, and three (9%) cerebrovascular involvement. Twenty patients underwent 45 percutaneous transluminal angioplasty procedures and seven children surgeries. In 44% of the 16 patients who underwent only percutaneous transluminal angioplasty blood pressure was normalized, 38% had improvement on same or decreased treatment and 19% showed no improvement. Complications were seen in 7.5% (5/66) of angiographies. In four of the seven (57%) children who underwent surgery blood pressure was normalized, two had improved (29%) and one unchanged (14%) blood pressure. CONCLUSION: In small children with renovascular hypertension below the age of 2 years, percutaneous transluminal angioplasty caused significant improvement in blood pressure with low complication profile. Surgery can be recommended where percutaneous transluminal angioplasty and medical treatments failed. WHAT IS KNOWN: • Renovascular hypertension is diagnosed in all age groups from a few weeks of life until adulthood. • Both angioplasty and surgery are significantly more difficult to perform in small children and the published information on short and long-term outcome in these children is very scarce. WHAT IS NEW: • Children below the age of two years can safely and successfully undergo selective renal angiography and also safely be treated with angioplasty. • We here present a large group of babies and infants where angioplasty and in some cases surgery effectively and safely improved their blood pressure.

Long-term outcomes following failure of Nissen fundoplication.

PURPOSE: To determine the management and outcomes of patients with gastro-oesophageal reflux (GOR) that requires further intervention following failure of Nissen fundoplication (NF). METHODS: After institutional audit department approval, a retrospective review of paediatric patients who had further intervention following failure of primary NF between January 2006 and December 2015 for GOR at our centre was performed. Data are presented as median (range). RESULTS: Of 820 patients who underwent NF, 190 (23%) received further procedures for GOR management at a median of 21 months of age (6-186); 90/190 (47%) had gastro-jejunal feeding (GJ). Of these, 67 (74%) remained on GJ feeds up to a median of 48 months and 23/90 (26%) had a second NF after GJ feeding. 97/190 (51%) had a redo fundoplication without having had a GJ; thus, 120/190 (63%) of patients having a further procedure went on to have a second NF after a median period of 15 months (1-70 months). Three patients (2%) had early emergency wrap revision 4 days after first fundoplication (we classed this as an 'early complication'). Of the seven patients who failed a 3rd NF, 4 continued GJ feeding, 2 of had oesophagogastric dissociation; 2 had 4th NF of which 1 was successful and 1 patient had gastric pacemaker and is successfully feeding orally. Patients who were finally successfully managed with GJ underwent 2 (2-5) tube changes/year. We found patients who had a previous GJ were more likely to have failure of the redo fundoplication than those who had not to have the GJ (16/24 vs. 30/90, p = 0.005). CONCLUSION: The chance of success decreases with every further attempt at fundoplication. The only factor significantly associated with failure of redo fundoplication was whether the patient previously had a GJ tube. In patients with failed fundoplications, when symptom free on jejunal feedings, further anti-reflux surgical intervention should be avoided. A randomized prospective study is needed for patient selection.

Cost evaluation of two types of gastrojejunal feeding tubes used in pediatric patients.

BACKGROUND: Gastrojejunal tubes are important feeding devices for children with gastro-esophageal reflux, allowing medication and feeding into the small bowel, and allowing gastric venting to prevent reflux. As with many medical devices, there are multiple manufacturers and designs, including balloon-retained tubes and disc-retained tubes. OBJECTIVE: This study evaluated the cost difference between these two types of gastrojejunal tube. MATERIALS AND METHODS: We conducted a 3.5-year retrospective cost evaluation for all pediatric patients undergoing an insertion or change of gastrojejunal tube using a bottom-up micro-costing analysis. We calculated days between encounters and a subsequent cost per day for each patient. RESULTS: A total of 187 children and adolescents were included, with an average age of 9.2 years. They underwent a total of 1,240 encounters, an average of 6.6 encounters per patient during the study period. A total of 82% of these encounters were related to balloon-retained tubes and 18% to disc-retained tubes. The most common reason for an encounter was a routine change (57%), with mechanical complications accounting for 31%. Disc-retained tubes had a longer period between encounters (117.5 days) than balloon-retained tubes (95 days; P=0.038). However, disc-retained tubes cost 6.9 British pound sterling (GBP) per day, which was significantly higher than balloon-retained tubes at 5.2 GBP per day (P<0.0001). CONCLUSION: Despite being more expensive to purchase, balloon-retained tubes were noted to be the least costly device in a cost-per-day analysis.

Importance of Magnetic Resonance Imaging With Diffusion-weighted Imaging in Guiding Biopsy of Nodular Ganglioneuroblastoma: A Case Report.

BACKGROUND: Nodular ganglioneuroblastoma is a rare peripheral neuroblastic tumor of variable prognosis. Accurate diagnosis, staging, and risk categorization can be particularly challenging in patients with nodular ganglioneuroblastoma due to the inherent heterogeneity of these lesions. CASE PRESENTATION: We illustrate the use of diffusion-weighted magnetic resonance imaging to identify tumor nodules and guide tumor biopsy in an almost 5-year-old boy with a large abdominal tumor. CONCLUSIONS: Diffusion-weighted magnetic resonance imaging was successful in detecting and guiding biopsy of a poorly differentiated neuroblastoma nodule within the context of a well-differentiated ganglioneuroma, allowing the diagnosis and characterization of a ganglioneuroblastoma nodular, thus influencing the child's prognosis and treatment.

An automated framework for localization, segmentation and super-resolution reconstruction of fetal brain MRI.

High-resolution volume reconstruction from multiple motion-corrupted stacks of 2D slices plays an increasing role for fetal brain Magnetic Resonance Imaging (MRI) studies. Currently existing reconstruction methods are time-consuming and often require user interactions to localize and extract the brain from several stacks of 2D slices. We propose a fully automatic framework for fetal brain reconstruction that consists of four stages: 1) fetal brain localization based on a coarse segmentation by a Convolutional Neural Network (CNN), 2) fine segmentation by another CNN trained with a multi-scale loss function, 3) novel, single-parameter outlier-robust super-resolution reconstruction, and 4) fast and automatic high-resolution visualization in standard anatomical space suitable for pathological brains. We validated our framework with images from fetuses with normal brains and with variable degrees of ventriculomegaly associated with open spina bifida, a congenital malformation affecting also the brain. Experiments show that each step of our proposed pipeline outperforms state-of-the-art methods in both segmentation and reconstruction comparisons including expert-reader quality assessments. The reconstruction results of our proposed method compare favorably with those obtained by manual, labor-intensive brain segmentation, which unlocks the potential use of automatic fetal brain reconstruction studies in clinical practice.

Diagnostic yield and safety of ultrasound-guided bowel mass biopsies in children.

BACKGROUND: Traditionally, ultrasound (US)-guided bowel mass biopsies are avoided in favour of endoscopic or surgical biopsies. However, endoscopy cannot easily reach lesions between the duodenojejunal flexure and the terminal ileum and lesions not involving the mucosa may not be accessible via an endoscopic route. OBJECTIVE: The aim of this study was to report our technique and to assess the diagnostic accuracy and safety of US-guided biopsy of bowel masses in children. MATERIALS AND METHODS: We conducted a 14-year retrospective review of US-guided bowel mass biopsies at a single paediatric hospital. RESULTS: Twenty US-guided bowel mass biopsies were performed in 19 patients (median age: 6 years and 6 months, range: 22 months-17 years, median weight: 22 kg, range: 10.2-48.4 kg). For 14 biopsies, there was no other lesion that could potentially be biopsied. A percutaneous coaxial technique was used for 19 biopsies and a transanal non-coaxial biopsy was performed in 1. A median of 9 (range: 2-15) cores of tissue was obtained at each biopsy. The technical success rate and adequacy of diagnostic yield were 100%. The most common diagnosis was lymphoma, which occurred in 16 biopsies. Three biopsies contained mucosa. There was one complication out of 20 biopsies (5%, 95% confidence interval 0-15%): a self-limiting, post biopsy pyrexia. Nineteen procedures were accompanied by a bone marrow aspirate and/or trephine within 2 weeks of the bowel biopsy, only one of which was diagnostic. CONCLUSION: US-guided bowel mass biopsy can be performed safely in children, with a high diagnostic yield and low complication rate.

Quantitative color-coded digital subtraction neuroangiography for pediatric arteriovenous shunting lesions.

BACKGROUND: Several complex pediatric neurovascular conditions are amenable to endovascular treatment. Given the unique anatomical and physiological challenges in children, there is an ongoing need for tools and techniques that provide accurate information for treatment planning, while minimizing exposure to ionizing radiation and contrast. This is more so for neonates and infants with high-flow arteriovenous (AV) shunts that are challenging to assess using conventional techniques. OBJECTIVE: In this brief report, we describe, through representative cases, the potential role of quantitative color-coded digital subtraction angiography (qDSA) in neuroendovascular procedures in children with high-flow AV shunting lesions. METHODS: Images were obtained using an ArtisQ biplane system (Siemens Healthineers, Erlangen, Germany). Post-processing was performed at a dedicated workstation (Syngo, Siemens) using the iFlow module to generate color-coded maps of individual digital subtraction angiography runs. CONCLUSION: Color-coded qDSA provides real-time quantitative information in high-flow AV shunting neurovascular lesions. This can potentially help direct treatment choices, optimize endovascular treatment protocols, monitor outcomes, and determine treatment end points.

Super-resolution for upper abdominal MRI: Acquisition and post-processing protocol optimization using brain MRI control data and expert reader validation.

PURPOSE: Magnetic resonance (MR) cholangiopancreatography (MRCP) is an established specialist method for imaging the upper abdomen and biliary/pancreatic ducts. Due to limitations of either MR image contrast or low through-plane resolution, patients may require further evaluation with contrast-enhanced computed tomography (CT) images. However, CT fails to offer the high tissue-ductal-vessel contrast-to-noise ratio available on T2-weighted MR imaging. METHODS: MR super-resolution reconstruction (SRR) frameworks have the potential to provide high-resolution visualizations from multiple low through-plane resolution single-shot T2-weighted (SST2W) images as currently used during MRCP studies. Here, we (i) optimize the source image acquisition protocols by establishing the ideal number and orientation of SST2W series for MRCP SRR generation, (ii) optimize post-processing protocols for two motion correction candidate frameworks for MRCP SRR, and (iii) perform an extensive validation of the overall potential of upper abdominal SRR, using four expert readers with subspeciality interest in hepato-pancreatico-biliary imaging. RESULTS: Obtained SRRs show demonstrable advantages over traditional SST2W MRCP data in terms of anatomical clarity and subjective radiologists' preference scores for a range of anatomical regions that are especially critical for the management of cancer patients. CONCLUSIONS: Our results underline the potential of using SRR alongside traditional MRCP data for improved clinical diagnosis.

Pancreatic pseudocyst drainage in children by image-guided cystogastrostomy and stent insertion.

BACKGROUND: Endoscopic ultrasound is seldom available at paediatric centres; therefore drainage of pancreatic pseudocysts in children has traditionally been achieved by surgery. OBJECTIVE: This study assessed the feasibility and safety of performing image-guided internal drainage of pancreatic pseudocysts with a flanged self-expanding covered nitinol pancreatic pseudocyst drainage stent. MATERIALS AND METHODS: We conducted a retrospective case note review of children undergoing image-guided cystogastrostomy at two paediatric hospitals. Percutaneous access to the stomach was achieved via an existing gastrostomy tract or image-guided formation of a new tract. Under combined ultrasound, fluoroscopic or cone-beam CT guidance the pancreatic pseudocysts were punctured through the posterior wall of the stomach. A self-expanding covered nitinol stent was deployed to create a cystogastrostomy opening. RESULTS: Image-guided cystogastrostomy was performed in 6 children (4 male; median age 6 years, range 46 months to 15 years; median weight 18 kg, range 13.8-47 kg). Two children had prior failed attempts at surgical or endoscopic drainage. Median maximum cyst diameter was 11.5 cm (range 4.7-15.5 cm) pre-procedure. Technical success was 100%. There were no complications. There was complete pseudocyst resolution in five children and a small (2.1-cm) residual pseudocyst in one. Pseudocyst-related symptoms resolved in all children. CONCLUSION: Pancreatic pseudocyst drainage can be successfully performed in children by image-guided placement of a cystogastrostomy stent. In this cohort of six children there were no complications.

Validation of the Fetal Lamb Model of Spina Bifida.

A randomized trial demonstrated that fetal spina bifida (SB) repair is safe and effective yet invasive. New less invasive techniques are proposed but are not supported by adequate experimental studies. A validated animal model is needed to bridge the translational gap to the clinic and should mimic the human condition. Introducing a standardized method, we comprehensively and reliably characterize the SB phenotype in two lamb surgical models with and without myelotomy as compared to normal lambs. Hindbrain herniation measured on brain magnetic resonance imaging (MRI) was the primary outcome. Secondary outcomes included gross examination with cerebrospinal fluid (CSF) leakage test, neurological examination with locomotor assessment, whole-body MRI, motor and somatosensory evoked potentials; brain, spinal cord, hindlimb muscles, bladder and rectum histology and/or immunohistochemistry. We show that the myelotomy model best phenocopies the anatomy, etiopathophysiology and symptomatology of non-cystic SB. This encompasses hindbrain herniation, ventriculomegaly, posterior fossa anomalies, loss of brain neurons; lumbar CSF leakage, hindlimb somatosensory-motor deficit with absence of motor and somatosensory evoked potentials due to loss of spinal cord neurons, astroglial cells and myelin; urinary incontinence. This model obtains the highest validity score for SB animal models and is adequate to assess the efficacy of novel fetal therapies.

Non-vascular interventional radiology in the paediatric alimentary tract.

Paediatric interventional radiology is an evolving speciality which is able to offer numerous minimally invasive treatments for gastrointestinal tract pathologies. Here we describe interventions performed by paediatric interventional radiologists on the alimentary tract from the mouth to the rectum. The interventions include sclerotherapy, stricture management by dilation, stenting and adjunctive therapies such as Mitomycin C administration and enteral access for feeding, motility assessment and administration of enemas.

Quantifying the Intra-Operative Hemodynamic Effects of Glue Embolization in Vein of Galen Malformations.

Vein of Galen malformation is a rare congenital pathological intracranial arteriovenous shunt which carries 30% risk of death before 28 days-of-age. Treatment is by high risk minimally invasive endovascular glue embolization of shunt feeding arteries under angiographic control. A tool to support intra-operative decision making would be useful. We present a novel method for visualizing angiography data to demonstrate the effect of the intervention based upon change the after embolization in the delay in time of peak contrast density relative to the injected artery and a novel method for quantifying the immediate effect of embolization on the hemodynamics of the shunt. The method is demonstrated on the angiograms of five neonates who underwent embolization. We show consistent results including a post-embolization increase in the delay in time of peak contrast density relative to the injected artery at the venous outflow in keeping with reduced shunting and redistribution of blood following embolization.

DeepIGeoS: A Deep Interactive Geodesic Framework for Medical Image Segmentation.

Accurate medical image segmentation is essential for diagnosis, surgical planning and many other applications. Convolutional Neural Networks (CNNs) have become the state-of-the-art automatic segmentation methods. However, fully automatic results may still need to be refined to become accurate and robust enough for clinical use. We propose a deep learning-based interactive segmentation method to improve the results obtained by an automatic CNN and to reduce user interactions during refinement for higher accuracy. We use one CNN to obtain an initial automatic segmentation, on which user interactions are added to indicate mis-segmentations. Another CNN takes as input the user interactions with the initial segmentation and gives a refined result. We propose to combine user interactions with CNNs through geodesic distance transforms, and propose a resolution-preserving network that gives a better dense prediction. In addition, we integrate user interactions as hard constraints into a back-propagatable Conditional Random Field. We validated the proposed framework in the context of 2D placenta segmentation from fetal MRI and 3D brain tumor segmentation from FLAIR images. Experimental results show our method achieves a large improvement from automatic CNNs, and obtains comparable and even higher accuracy with fewer user interventions and less time compared with traditional interactive methods.

Arterial Recanalization for Access for Arterial Intervention in Children: Techniques and Outcomes.

PURPOSE: To assess technical success of arterial recanalization in children requiring repeated arterial access and intervention. MATERIALS AND METHODS: Over 14 years, 41 attempts to cross 30 arterial occlusions were made in 22 patients (13 male, 9 female). Median patient age was 12 months (15 days-14 years), and weight was 7.6 kg (3.0-77.3 kg). Techniques and outcomes were recorded. RESULTS: Twenty-five of 41 (61%) attempts at crossing an arterial occlusion were successful. Nineteen of 30 (63%) first attempts to cross occlusions were successful, and 6 of 11 (55%) repeat attempts were successful. The occluded segments were combinations of common femoral artery (n = 4), external iliac artery (n = 36), common iliac artery (n = 11), and aorta (n = 1). Complications occurred in 5 of 41(12%) attempts: 3 minor complications (hematoma, extravasation, and transient leg ischemia) and 2 major complications (rupture and thrombosis). CONCLUSIONS: Arterial access by recanalization of occluded segments is technically feasible in children, with a low complication rate.