- Email: [email protected]
Interventional radiology in infancy
Early Human Development 90 (2014) 787–790
Contents lists available at ScienceDirect
Early Human Development journal homepage: www.elsevier.com/locate/earlhumdev
Interventional radiology in infancy Alex M. Barnacle ⁎ Department of Radiology, Great Ormond Street Hospital for Children, London WC1N 3JH, United Kingdom
a r t i c l e
i n f o
a b s t r a c t Interventional radiology (IR) is an emerging sub-speciality within paediatric medicine. In adult care, IR is largely centred on the management of vascular disease but in paediatric practice, IR applications are varied and increasingly innovative, making this an exciting field to be a part of. IR has a central role both in the day to day care of sick children, from long term IV access provision to feeding tube insertions, and in the acute management of critically ill infants, such as those with overwhelming liver disease, neonatal tumours and vascular malformations. Paediatric IR faces a unique set of challenges, developing or modifying techniques and equipment for use in very small patients, training professionals to take the speciality forward and, most importantly, convincing paediatricians and healthcare institutions to create opportunities for IR to make a difference. © 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Interventional radiology Paediatric Intravenous access Biopsy Vascular malformation Embolisation
Contents 1. Introduction . . . . . . . . . 2. Intravenous access . . . . . . 3. Biopsy . . . . . . . . . . . . 4. Gastrointestinal intervention. . 5. Aspiration and drainage . . . . 6. Airway intervention. . . . . . 7. Vascular anomalies . . . . . . 8. Angiography and embolisation . 9. Conclusion . . . . . . . . . . Conflict of interest . . . . . . . . . References . . . . . . . . . . . .
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1. Introduction Interventional radiology (IR) is well established in adult medical practice but has been slow to develop in paediatric care. The reasons for this can be debated but include the challenges of adapting alreadycomplex techniques for use in small patients, the lack of industry-led innovation on paediatric-specific IR devices, a relative low number of interventionalists from traditional adult vascular surgery backgrounds willing to consider a career involving paediatric medical expertise and interaction with small children and their families, as well as a frustratingly widespread lack of vision by medical institutions in embracing the speciality. But it can no longer be denied that IR brings a wide range of new approaches to many aspects of neonatal and paediatric care, offering not only quicker, less painful minimally invasive options ⁎ Tel.: +44 207 8297943. E-mail address: [email protected].
http://dx.doi.org/10.1016/j.earlhumdev.2014.08.017 0378-3782/© 2014 Elsevier Ireland Ltd. All rights reserved.
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787 787 788 788 789 789 789 790 790 790 790
for many procedures but also emergency interventions for very sick children unable to tolerate complex surgery. Not only does IR offer alternatives to more traditional surgical approaches, it is also developing new treatments previously unavailable for many conditions and changing the future for many children and families.
2. Intravenous access Provision of medium to long term intravenous access devices for children, for many decades the responsibility of paediatric surgeons, is fast becoming the remit of IR. It has been clearly demonstrated that image guidance increases the safety and efficiency of central venous catheter (CVC) placement [1]. The UK National Institute for Health and Care Excellence (NICE) stated as long ago as 2002 that ultrasound imaging guidance should be the preferred method for CVC placement in adults and children in elective situations and should be considered
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in most clinical situations where CVC insertion is necessary, whether the situation is elective or an emergency [2]. The particular strengths of an IR-led image-guided technique are that a suitable route of access can be planned before any incision or surgical exploration is undertaken and that the vein is usually preserved for future access. In the early days of IR, many long-term patients presented after multiple previous surgical access procedures. The majority of central veins would be lost and increasingly heroic IR options were required to place a CVC, including transhepatic, transrenal or translumbar routes. Patients managed in an institution with ready access to an IR-led vascular access service present with this scenario increasingly rarely and central venous access should now be straightforward in the majority of cases. In instances where children have lost access routes due to previous procedures, IR techniques originally developed for peripheral arterial work in adults are modified to negotiate small collateral venous channels, stent venous stenoses and recanalise central vessels. Any paediatric healthcare institution should have a robust central venous access policy which details the decision-making process when choosing a suitable central venous access device for a child and formalises the progression from ward or intensive care-based cannulation procedures for short-term lines to surgical or IR-led procedures in a dedicated operating suite for long term access. The majority of institutions agree that the remit of IR is solely for the placement of medium to long-term devices. The most common indications for central venous access referral in infants include extended intravenous antibiotic or antiviral courses, parenteral nutrition, dialysis and chemotherapy. Specialised centres will also require reliable access for children with haemophilia, enzyme replacement therapy and metabolic conditions such as hyperinsulinism. Recently there has been a move towards IR involvement in cannulation for extracorporeal membrane oxygenation (ECMO) programs. In paediatric practice, there is of course also a drive for intravenous access solutions for children with needle phobia and difficult peripheral venous access. Device options vary from 2-5Fr peripherally inserted CVCs (PICCs) to 11Fr dual lumen cuffed tunnelled CVCs, the details of which are beyond the scope of this review but are well documented elsewhere [3]. Decisions need to be made about whether a device should be peripherally inserted, tunnelled or totally implanted and whether the procedure can be performed with the child awake. Consideration should also be given to whether a local team can manage the child's device after discharge from hospital and whether general anaesthesia is required for device removal. Clinical teams looking after complex inpatients will often be tempted to request a device with the greatest number of lumens but this needs to be balanced with other considerations such as the size of the catheter relative to the child (large catheters in small children can be associated with acute superior vena cava obstruction or long term central vessel occlusion) and the need for reliable withdrawal rates (catheters with multiple lumens tend to have smaller calibre individual lumens which may not aspirate well). Many paediatric centres with well-established IR practices advocate the development of an IR-led vascular access team. This service can be nurse-led and should coordinate the decision-making process when a child first requires long term access, family education, monitoring of indwelling lines, troubleshooting of faulty devices on the wards and liaison with the community upon patient discharge. Currently, IR has limited involvement with patients once devices are placed and this must be detrimental to the patient and the process, under-using IR's skills in diagnosing and managing malfunctioning catheters and limiting data collection on long term line outcomes [4]. 3. Biopsy The commonest indications for biopsy in infants are suspected malignancy, hepatic disease, renal disease, infection and the investigation of some soft tissue masses [5]. Liver biopsy may also be indicated in infants with suspected biliary atresia [5]. Soft tissue masses and suspected
malignancies should be carefully imaged with ultrasound in the first instance, as the diagnosis can often be reached on imaging features alone. Complex masses with deep extension should then be assessed with detailed cross-sectional imaging, ideally MRI, to document the anatomical relations of the tumour, its vascular supply and its tissue viability. It makes a significant difference to biopsy planning, for instance, to know that a lesion is within, rather than adjacent to, the liver, and biopsy should be targeted at the most viable tissue within the mass to optimise the quality of the samples obtained. Infants with abdominal malignancies often present with very large tumours and the organ of origin can sometimes be difficult to determine on initial imaging. Much of the tumour is often necrotic at presentation, having outgrown its blood supply, so biopsy must be directed towards the well-perfused, viable parts of the mass. It is also critical to look for secondary masses during imaging work-up, as there may be satellite or secondary lesions that are more easily accessed than the primary tumour. Because neonatal and infant tumours are usually large and because the child is small, most lesions are relatively superficial and can be accessed percutaneously using ultrasound guidance alone [5]. It is rare to need cross sectional imaging guidance but occasionally CT proves invaluable. Many modern IR suites have inbuilt cone-beam CT technology which allows for a single 200 degree rotation of the X-ray C-arm, generating a volumetric dataset which can be reconstructed into cross sectional images. This significant technical advance allows for realtime CT imaging during an IR procedure and affords the radiologist an opportunity to confirm, for instance, biopsy needle position for small or relatively inaccessible lesions. Abdominal and chest mass biopsies can be performed using a coaxial biopsy needle system, which allows for only one breach of the tumour capsule. Multiple cores can then be obtained using the inner needle. This reduces the risks of bleeding and inadvertent damage to other structures compared to multiple biopsy needle passes and provides an opportunity to embolise or plug the biopsy track as the outer needle is finally withdrawn. This is likely to reduce the risk of tumour spill, so is of particular importance in hepatoblastoma and renal tumour biopsy.
4. Gastrointestinal intervention Indications for feeding tube placement in infants are rare but do occur. Gastrostomy tube insertion may be indicated in children unable to take oral feeds due to an unsafe swallow secondary to neurological impairment, those with specific nutrition or medication demands (renal failure, cystic fibrosis, certain metabolic conditions) and those with severe oesophageal disease such as caustic strictures. Gastrostomy devices are placed by IR, gastroenterology or paediatric surgery, using a range of techniques. In infants, gastrostomy tube insertion is often combined with fundoplication in patients with severe reflux and therefore a combined surgical approach is indicated. However, image-guided percutaneous gastrostomy tube placement by IR is well described and this quick, minimally invasive technique can be advantageous in small children [6]. There is still conflicting evidence as to whether surgical or IR techniques are safer or more successful [6,7]. IR-guided balloon dilatation has a central role in the management of oesophageal strictures. A proportion of strictures are secondary to foreign body obstruction, caustic ingestion or epidermolysis bullosa (EB), but in infancy, the commonest indication for dilatation is anastamotic stricture secondary to oesophageal atresia (EA) repair. Anastamotic strictures occur in 18–55% of patients following surgical repair of EA but respond well to serial balloon dilatation [8,9]. An image-guided technique allows accurate visualisation of the entire length of the stricture and for both safe crossing of the stricture with a hydrophilic guidewire and controlled balloon dilatation under real-time fluoroscopic control. Complication rates are very low, with oesophageal rupture rates of b1% [9].
A.M. Barnacle / Early Human Development 90 (2014) 787–790
5. Aspiration and drainage Image-guided aspiration and drain insertion techniques allow safer and more efficient treatment of collections, as adjacent solid organs, vessels and bowel can be more easily avoided and drains can be meticulously placed into the centre of collections. IR has additional expertise in the subsequent management of indwelling drains, with access to fluoroscopic ‘tube-checks’ and techniques available to replace malfunctioning drains over a guidewire. Although most collections are a result of infective processes in older children such as appendicitis, empyema and pancreatitis, there are some indications for aspiration and drainage in infants. These include drainage of extensive pleural collections or ascites, diagnostic taps of osteomyelitis-related collections, decompression of acute neonatal hydronephrosis and peri-renal urinomas and, rarely, severe hydrocolpos collections in infants with anorectal malformations. Almost all collections can be accessed with ultrasound guidance alone, because most structures are inevitably superficial in very small children. Drain size ranges from 5-12Fr but small gauge drains usually suffice for the indications listed above. Because most procedures are ultrasound-guided and involve a simple Seldinger technique and the use of standard puncture needles and guidewires, drainage and aspiration can often be performed at the bedside on a neonatal intensive care unit if required. 6. Airway intervention It is increasingly common for IR to be asked to investigate or treat infants with airway obstruction. Patients may present with stridor, recurrent apnoeas or ventilator dependence. The commonest cause of airway obstruction in infants is tracheobronchial malacia but congenital tracheal stenosis (secondary to complete tracheal rings), extrinsic compression (such as from vascular rings) and intraluminal obstructive lesions also occur. Children with complex airway disease should be managed by a specialist multidisciplinary team, including intensivists, respiratory physicians, cardiothoracic and ENT surgeons and paediatricians. In some centres, IR has developed a key role in this team, using bronchoscopy and bronchography to diagnosis malacia and tracheal stenosis, and using IR techniques such as balloon dilatation and stenting to treat complex obstructive disease [9,10]. Bronchography, once relegated to the history books by the advent of cross sectional imaging, has re-emerged as an invaluable tool in the dynamic assessment of the infant airway. Ideally performed in a biplane angiography suite, low-osmolality water-soluble contrast medium is injected through either the working channel of a bronchoscope or through a small angiography catheter placed in the upper trachea. Contrast medium coats the surface of the airway and delineates the trachea, major and segmental bronchi, demonstrating anatomical variants and intrinsic obstructive lesions. If the patient is spontaneously breathing, high-resolution, fast frame rate image acquisition in AP and lateral planes exquisitely demonstrates any malacia of the trachea or bronchi. By introducing a manometer into the breathing circuit, the opening pressure of malacic segments can be determined. This information can be invaluable in the management of neonates with ventilator dependency.
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in the embolisation of such lesions but this is now almost entirely obsolete. Congenital haemangiomas are distinct from infantile haemangiomas. They occur far less commonly, are fully grown at birth and are negative for GLUT1 on immunohistochemical staining, unlike infantile lesions, which appear in early infancy and demonstrate GLUT1 positivity. Many congenital haemangiomas shrink very rapidly within a few months of age and are termed rapidly involuting congenital haemangiomas (RICHs). Others do not involute at all (non-involuting congenital haemangiomas, NICHs). RICHs can be large and extremely hypervascular, and cause significant anxiety when they are found in a newborn child. They can be mistaken for common infantile haemangiomas or tumours and misdiagnosis or mistreatment is common [11]. Paediatric interventional radiologists tend to have considerable experience in the imaging and management of vascular anomalies and should be consulted early in such cases. Many haemangiomas are small and clinically insignificant but large lesions can occasionally compromise an infant due to their inherent hypervascularity or mass effect. This is most commonly encountered in the liver. Both infantile and congenital haemangiomas can occur within the liver; RICH lesions of the liver are usually large, solitary lesions while infantile haemangiomas are typically multifocal or diffuse. These latter lesions tended to be known as infantile haemangioendotheliomas but this confusing terminology has rightly fallen out of favour [11]. Although both types of liver lesion are benign and self-limiting, emergency embolisation may be required in the neonatal period due to massive cardiac overload or to overwhelming mass effect causing splinting of the diaphragm or abdominal compartment syndrome. Vascular malformations comprise a second type of vascular anomaly and are distinct from haemangiomas in that they are present from birth, never involute and grow commensurately with the child. High flow arteriovenous malformations (AVMs) are the group of malformations that most clinicians tend to be familiar with but in childhood, slow flow venous and lymphatic malformations present far more commonly. The lesions that cause the most morbidity in infancy are large cervicofacial lymphatic malformations, also known as cystic hygromas (Fig. 1). If diagnosed antenatally, an ex utero intrapartum treatment (EXIT) procedure can be considered at delivery. These patients require the skills of a specialist multidisciplinary team, including ENT surgery, craniofacial surgery and IR. Many children require a tracheostomy for the first few years of life. Management is aimed at a staged debulking
7. Vascular anomalies The commonest vascular anomaly presenting in infancy is the infantile haemangioma, occurring in up to 10% of Caucasian infants. The management of these lesions has been transformed by the use of the beta blocker propanolol, which dramatically accelerates the regression of these haemangiomas. Extensive lesions causing clinical problems such as obstruction of the airway or visual axis can now be treated quickly with medication alone. Historically, IR had an occasional role
Fig. 1. Sagittal T1-weighted MRI image of a 1-week-old female with an extensive cervicofacial lymphatic malformation.
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IR operators and radiographers must employ meticulous radiation dose reduction techniques during angiography, as these can be high dose procedures. Of equal concern is the volume of contrast medium required, especially for a complex embolisation. Most operators, using non-ionic contrast medium 240 mgI/ml, will aim for a maximum dose of 4–5 ml/kg per procedure, although in reality far higher doses (up to 10 ml/kg) are often tolerated. Alongside this, saline flush volumes must be carefully monitored and the anaesthetist must be kept informed of the volumes being used. Assuming there are no acute contraindications, intravenous heparin is usually given after securing arterial access (usually 50–100 U/kg) [13]. Lesion type and morphology will dictate the embolic agent used; operators need to consider the intended outcome of embolisation (total occlusion of vascular supply or just a temporary reduction in flow) and the lesion’s flow characteristics and vascular anatomy. Embolisation choices in neonates and infants are further complicated by the need to consider the total of volume of liquid embolic that can be used and the volume of contrast needed to deliver particulate embolics. Onyx (Covidien, Plymouth MN) use is limited by the volume of associated DMSO solvent that can be tolerated. Fig. 2. Axial T2-weighted MRI image of the abdomen in a 2-week-old female with neuroblastoma stage MS. There is massive infiltration and expansion of the liver by tumour (intermediate to high signal tissue). The small volume of normal liver parenchyma (low signal tissue) is seen centrally, around the portal tracts.
of the lesion, usually by a combination of sclerotherapy and surgery. Percutaneous sclerotherapy is performed by IR, usually using simple ultrasound guidance and a range of sclerosing agents. The commonest agents available are sodium tetradecyl sulfate (STS), doxycycline, dehydrated alcohol and bleomycin. Most sclerosants cause inflammation of the cysts within the lymphatic malformation followed by chronic scarring, so that the cysts flatten and do not refill with fluid. Bleomycin has a different action, causing DNA breakage and cell destruction, and hence it is usually recommended for malformations with smaller ‘microcysts’ and more solid disease. Patients with extensive malformations, such as the child imaged in Fig. 1, will require multiple sclerotherapy and surgical procedures over several years but in experienced hands the outcomes are reasonable and most children achieve decannulation [12].
8. Angiography and embolisation Angiography and embolisation in sick neonates and infants are highly specialised procedures requiring expert paediatric IR skills [13]. Indications for embolisation include infantile or congenital haemangiomas causing cardiac failure or severe mass effect, extensive liver infiltration and associated mass effect in neuroblastoma stage MS (Fig. 2), arteriovenous shunts (including vein of Galen malformations), and bleeding. Chemoembolisation of liver tumours has also been reported. Detailed management of these conditions is beyond the scope of this paper but the general principles of arterial intervention are common to all. Arterial access is usually via the femoral vessels, as in adults, but this can be difficult in neonates with extensive liver disease in whom aortic blood flow beyond the celiac axis can be markedly reduced. The axillary arteries are a valuable alternative access route in such patients and a left axillary artery approach often gives a better angle for cannulation of the hepatic artery. In the first few days of life, umbilical artery access is often also possible. 3Fr or 4Fr vascular access sheaths are usually sufficient in calibre for most procedures.
9. Conclusion IR is a key resource in the management of sick neonates and infants. IR techniques provide fast, non-traumatic, minimally invasive options for many procedures in children and new treatments are being developed to push the boundaries of what can be achieved. IR requires the support and encouragement of specialist paediatric centres, research institutions and industry to allow it to flourish and innovate. Conflict of interest None. References [1] Nosher JL, Shami MM, Siegel RL, DeCandia M, Bodner LJ. Tunneled central venous access catheter placement in the pediatric population: comparison of radiologic and surgical results. Radiology 1994;192:265–8. [2] National Institute for Health and Care Excellence. Guidance on the use of ultrasound locating devices for placing central venous catheters TA49. London: National Institute for Health and Care Excellence; 2002. [3] Vo J, Hoffer FA, Shaw DWW. Techniques in vascular and interventional radiology: pediatric central venous access. Tech Vasc Interv Radiol 2010;13:250–7. [4] Barnacle A, Arthurs OJ, Roebuck D, Hiorns M. Malfunctioning central venous catheters in children: a diagnostic approach. Pediatr Radiol 2008;38:363–78. [5] Hogan MJ, Hoffer FA. Biopsy and drainage techniques in children. Tech Vasc Interv Radiol 2010;13:206–13. [6] Connolly B, Krishnamurthy G, Amaral J. Upper gastrointestinal access in children: techniques and outcomes. Tech Vasc Interv Radiol 2010;13:222–8. [7] Nah SA, Narayanaswarmy B, Eaton S, Coppi PD, Kiely EM, Curry JI, et al. Gastrostomy insertion in children: percutaneous endoscopic or percutaneous image-guided? J Pediatr Surg 2010;45:1153–8. [8] Ko HK, Shin JH, Song HY, Kim YJ, Ko GY, Yoon HK, et al. Balloon dilatation of anastamotic strictures secondary to surgical repair of esophageal atresia in a pediatric population: long term results. J Vasc Interv Radiol 2006;17:1327–33. [9] Roebuck DJ, Hogan MJ, Connolly B, McLaren CA. Interventions in the chest in children. Tech Vasc Interv Radiol 2011;14:8–15. [10] McLaren CA, Elliott MJ, Roebuck DJ. Tracheobronchial intervention in children. Eur J Radiol 2005;53:22–34. [11] Roebuck DJ, Sebire N, Lehmann, Barnacle A. Rapidly involuting haemangioma (RICH) of the liver. Pediatr Radiol 2012;42:308–14. [12] Cahill AM, Nijs E, Ballah D, Rabinowitz D, Thompson L, Rintoul N, et al. Percutaneous sclerotherapy in neonatal and infant head and neck lymphatic malformations: a single center experience. J Pediatr Surg 2011;46:2083–95. [13] Lord DJ, Chennapragada SM. Embolization in neonates and infants. Tech Vasc Interv Radiol 2011;14:32–41.
Contents lists available at ScienceDirect
Early Human Development journal homepage: www.elsevier.com/locate/earlhumdev
Interventional radiology in infancy Alex M. Barnacle ⁎ Department of Radiology, Great Ormond Street Hospital for Children, London WC1N 3JH, United Kingdom
a r t i c l e
i n f o
a b s t r a c t Interventional radiology (IR) is an emerging sub-speciality within paediatric medicine. In adult care, IR is largely centred on the management of vascular disease but in paediatric practice, IR applications are varied and increasingly innovative, making this an exciting field to be a part of. IR has a central role both in the day to day care of sick children, from long term IV access provision to feeding tube insertions, and in the acute management of critically ill infants, such as those with overwhelming liver disease, neonatal tumours and vascular malformations. Paediatric IR faces a unique set of challenges, developing or modifying techniques and equipment for use in very small patients, training professionals to take the speciality forward and, most importantly, convincing paediatricians and healthcare institutions to create opportunities for IR to make a difference. © 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Interventional radiology Paediatric Intravenous access Biopsy Vascular malformation Embolisation
Contents 1. Introduction . . . . . . . . . 2. Intravenous access . . . . . . 3. Biopsy . . . . . . . . . . . . 4. Gastrointestinal intervention. . 5. Aspiration and drainage . . . . 6. Airway intervention. . . . . . 7. Vascular anomalies . . . . . . 8. Angiography and embolisation . 9. Conclusion . . . . . . . . . . Conflict of interest . . . . . . . . . References . . . . . . . . . . . .
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1. Introduction Interventional radiology (IR) is well established in adult medical practice but has been slow to develop in paediatric care. The reasons for this can be debated but include the challenges of adapting alreadycomplex techniques for use in small patients, the lack of industry-led innovation on paediatric-specific IR devices, a relative low number of interventionalists from traditional adult vascular surgery backgrounds willing to consider a career involving paediatric medical expertise and interaction with small children and their families, as well as a frustratingly widespread lack of vision by medical institutions in embracing the speciality. But it can no longer be denied that IR brings a wide range of new approaches to many aspects of neonatal and paediatric care, offering not only quicker, less painful minimally invasive options ⁎ Tel.: +44 207 8297943. E-mail address: [email protected].
http://dx.doi.org/10.1016/j.earlhumdev.2014.08.017 0378-3782/© 2014 Elsevier Ireland Ltd. All rights reserved.
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for many procedures but also emergency interventions for very sick children unable to tolerate complex surgery. Not only does IR offer alternatives to more traditional surgical approaches, it is also developing new treatments previously unavailable for many conditions and changing the future for many children and families.
2. Intravenous access Provision of medium to long term intravenous access devices for children, for many decades the responsibility of paediatric surgeons, is fast becoming the remit of IR. It has been clearly demonstrated that image guidance increases the safety and efficiency of central venous catheter (CVC) placement [1]. The UK National Institute for Health and Care Excellence (NICE) stated as long ago as 2002 that ultrasound imaging guidance should be the preferred method for CVC placement in adults and children in elective situations and should be considered
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in most clinical situations where CVC insertion is necessary, whether the situation is elective or an emergency [2]. The particular strengths of an IR-led image-guided technique are that a suitable route of access can be planned before any incision or surgical exploration is undertaken and that the vein is usually preserved for future access. In the early days of IR, many long-term patients presented after multiple previous surgical access procedures. The majority of central veins would be lost and increasingly heroic IR options were required to place a CVC, including transhepatic, transrenal or translumbar routes. Patients managed in an institution with ready access to an IR-led vascular access service present with this scenario increasingly rarely and central venous access should now be straightforward in the majority of cases. In instances where children have lost access routes due to previous procedures, IR techniques originally developed for peripheral arterial work in adults are modified to negotiate small collateral venous channels, stent venous stenoses and recanalise central vessels. Any paediatric healthcare institution should have a robust central venous access policy which details the decision-making process when choosing a suitable central venous access device for a child and formalises the progression from ward or intensive care-based cannulation procedures for short-term lines to surgical or IR-led procedures in a dedicated operating suite for long term access. The majority of institutions agree that the remit of IR is solely for the placement of medium to long-term devices. The most common indications for central venous access referral in infants include extended intravenous antibiotic or antiviral courses, parenteral nutrition, dialysis and chemotherapy. Specialised centres will also require reliable access for children with haemophilia, enzyme replacement therapy and metabolic conditions such as hyperinsulinism. Recently there has been a move towards IR involvement in cannulation for extracorporeal membrane oxygenation (ECMO) programs. In paediatric practice, there is of course also a drive for intravenous access solutions for children with needle phobia and difficult peripheral venous access. Device options vary from 2-5Fr peripherally inserted CVCs (PICCs) to 11Fr dual lumen cuffed tunnelled CVCs, the details of which are beyond the scope of this review but are well documented elsewhere [3]. Decisions need to be made about whether a device should be peripherally inserted, tunnelled or totally implanted and whether the procedure can be performed with the child awake. Consideration should also be given to whether a local team can manage the child's device after discharge from hospital and whether general anaesthesia is required for device removal. Clinical teams looking after complex inpatients will often be tempted to request a device with the greatest number of lumens but this needs to be balanced with other considerations such as the size of the catheter relative to the child (large catheters in small children can be associated with acute superior vena cava obstruction or long term central vessel occlusion) and the need for reliable withdrawal rates (catheters with multiple lumens tend to have smaller calibre individual lumens which may not aspirate well). Many paediatric centres with well-established IR practices advocate the development of an IR-led vascular access team. This service can be nurse-led and should coordinate the decision-making process when a child first requires long term access, family education, monitoring of indwelling lines, troubleshooting of faulty devices on the wards and liaison with the community upon patient discharge. Currently, IR has limited involvement with patients once devices are placed and this must be detrimental to the patient and the process, under-using IR's skills in diagnosing and managing malfunctioning catheters and limiting data collection on long term line outcomes [4]. 3. Biopsy The commonest indications for biopsy in infants are suspected malignancy, hepatic disease, renal disease, infection and the investigation of some soft tissue masses [5]. Liver biopsy may also be indicated in infants with suspected biliary atresia [5]. Soft tissue masses and suspected
malignancies should be carefully imaged with ultrasound in the first instance, as the diagnosis can often be reached on imaging features alone. Complex masses with deep extension should then be assessed with detailed cross-sectional imaging, ideally MRI, to document the anatomical relations of the tumour, its vascular supply and its tissue viability. It makes a significant difference to biopsy planning, for instance, to know that a lesion is within, rather than adjacent to, the liver, and biopsy should be targeted at the most viable tissue within the mass to optimise the quality of the samples obtained. Infants with abdominal malignancies often present with very large tumours and the organ of origin can sometimes be difficult to determine on initial imaging. Much of the tumour is often necrotic at presentation, having outgrown its blood supply, so biopsy must be directed towards the well-perfused, viable parts of the mass. It is also critical to look for secondary masses during imaging work-up, as there may be satellite or secondary lesions that are more easily accessed than the primary tumour. Because neonatal and infant tumours are usually large and because the child is small, most lesions are relatively superficial and can be accessed percutaneously using ultrasound guidance alone [5]. It is rare to need cross sectional imaging guidance but occasionally CT proves invaluable. Many modern IR suites have inbuilt cone-beam CT technology which allows for a single 200 degree rotation of the X-ray C-arm, generating a volumetric dataset which can be reconstructed into cross sectional images. This significant technical advance allows for realtime CT imaging during an IR procedure and affords the radiologist an opportunity to confirm, for instance, biopsy needle position for small or relatively inaccessible lesions. Abdominal and chest mass biopsies can be performed using a coaxial biopsy needle system, which allows for only one breach of the tumour capsule. Multiple cores can then be obtained using the inner needle. This reduces the risks of bleeding and inadvertent damage to other structures compared to multiple biopsy needle passes and provides an opportunity to embolise or plug the biopsy track as the outer needle is finally withdrawn. This is likely to reduce the risk of tumour spill, so is of particular importance in hepatoblastoma and renal tumour biopsy.
4. Gastrointestinal intervention Indications for feeding tube placement in infants are rare but do occur. Gastrostomy tube insertion may be indicated in children unable to take oral feeds due to an unsafe swallow secondary to neurological impairment, those with specific nutrition or medication demands (renal failure, cystic fibrosis, certain metabolic conditions) and those with severe oesophageal disease such as caustic strictures. Gastrostomy devices are placed by IR, gastroenterology or paediatric surgery, using a range of techniques. In infants, gastrostomy tube insertion is often combined with fundoplication in patients with severe reflux and therefore a combined surgical approach is indicated. However, image-guided percutaneous gastrostomy tube placement by IR is well described and this quick, minimally invasive technique can be advantageous in small children [6]. There is still conflicting evidence as to whether surgical or IR techniques are safer or more successful [6,7]. IR-guided balloon dilatation has a central role in the management of oesophageal strictures. A proportion of strictures are secondary to foreign body obstruction, caustic ingestion or epidermolysis bullosa (EB), but in infancy, the commonest indication for dilatation is anastamotic stricture secondary to oesophageal atresia (EA) repair. Anastamotic strictures occur in 18–55% of patients following surgical repair of EA but respond well to serial balloon dilatation [8,9]. An image-guided technique allows accurate visualisation of the entire length of the stricture and for both safe crossing of the stricture with a hydrophilic guidewire and controlled balloon dilatation under real-time fluoroscopic control. Complication rates are very low, with oesophageal rupture rates of b1% [9].
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5. Aspiration and drainage Image-guided aspiration and drain insertion techniques allow safer and more efficient treatment of collections, as adjacent solid organs, vessels and bowel can be more easily avoided and drains can be meticulously placed into the centre of collections. IR has additional expertise in the subsequent management of indwelling drains, with access to fluoroscopic ‘tube-checks’ and techniques available to replace malfunctioning drains over a guidewire. Although most collections are a result of infective processes in older children such as appendicitis, empyema and pancreatitis, there are some indications for aspiration and drainage in infants. These include drainage of extensive pleural collections or ascites, diagnostic taps of osteomyelitis-related collections, decompression of acute neonatal hydronephrosis and peri-renal urinomas and, rarely, severe hydrocolpos collections in infants with anorectal malformations. Almost all collections can be accessed with ultrasound guidance alone, because most structures are inevitably superficial in very small children. Drain size ranges from 5-12Fr but small gauge drains usually suffice for the indications listed above. Because most procedures are ultrasound-guided and involve a simple Seldinger technique and the use of standard puncture needles and guidewires, drainage and aspiration can often be performed at the bedside on a neonatal intensive care unit if required. 6. Airway intervention It is increasingly common for IR to be asked to investigate or treat infants with airway obstruction. Patients may present with stridor, recurrent apnoeas or ventilator dependence. The commonest cause of airway obstruction in infants is tracheobronchial malacia but congenital tracheal stenosis (secondary to complete tracheal rings), extrinsic compression (such as from vascular rings) and intraluminal obstructive lesions also occur. Children with complex airway disease should be managed by a specialist multidisciplinary team, including intensivists, respiratory physicians, cardiothoracic and ENT surgeons and paediatricians. In some centres, IR has developed a key role in this team, using bronchoscopy and bronchography to diagnosis malacia and tracheal stenosis, and using IR techniques such as balloon dilatation and stenting to treat complex obstructive disease [9,10]. Bronchography, once relegated to the history books by the advent of cross sectional imaging, has re-emerged as an invaluable tool in the dynamic assessment of the infant airway. Ideally performed in a biplane angiography suite, low-osmolality water-soluble contrast medium is injected through either the working channel of a bronchoscope or through a small angiography catheter placed in the upper trachea. Contrast medium coats the surface of the airway and delineates the trachea, major and segmental bronchi, demonstrating anatomical variants and intrinsic obstructive lesions. If the patient is spontaneously breathing, high-resolution, fast frame rate image acquisition in AP and lateral planes exquisitely demonstrates any malacia of the trachea or bronchi. By introducing a manometer into the breathing circuit, the opening pressure of malacic segments can be determined. This information can be invaluable in the management of neonates with ventilator dependency.
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in the embolisation of such lesions but this is now almost entirely obsolete. Congenital haemangiomas are distinct from infantile haemangiomas. They occur far less commonly, are fully grown at birth and are negative for GLUT1 on immunohistochemical staining, unlike infantile lesions, which appear in early infancy and demonstrate GLUT1 positivity. Many congenital haemangiomas shrink very rapidly within a few months of age and are termed rapidly involuting congenital haemangiomas (RICHs). Others do not involute at all (non-involuting congenital haemangiomas, NICHs). RICHs can be large and extremely hypervascular, and cause significant anxiety when they are found in a newborn child. They can be mistaken for common infantile haemangiomas or tumours and misdiagnosis or mistreatment is common [11]. Paediatric interventional radiologists tend to have considerable experience in the imaging and management of vascular anomalies and should be consulted early in such cases. Many haemangiomas are small and clinically insignificant but large lesions can occasionally compromise an infant due to their inherent hypervascularity or mass effect. This is most commonly encountered in the liver. Both infantile and congenital haemangiomas can occur within the liver; RICH lesions of the liver are usually large, solitary lesions while infantile haemangiomas are typically multifocal or diffuse. These latter lesions tended to be known as infantile haemangioendotheliomas but this confusing terminology has rightly fallen out of favour [11]. Although both types of liver lesion are benign and self-limiting, emergency embolisation may be required in the neonatal period due to massive cardiac overload or to overwhelming mass effect causing splinting of the diaphragm or abdominal compartment syndrome. Vascular malformations comprise a second type of vascular anomaly and are distinct from haemangiomas in that they are present from birth, never involute and grow commensurately with the child. High flow arteriovenous malformations (AVMs) are the group of malformations that most clinicians tend to be familiar with but in childhood, slow flow venous and lymphatic malformations present far more commonly. The lesions that cause the most morbidity in infancy are large cervicofacial lymphatic malformations, also known as cystic hygromas (Fig. 1). If diagnosed antenatally, an ex utero intrapartum treatment (EXIT) procedure can be considered at delivery. These patients require the skills of a specialist multidisciplinary team, including ENT surgery, craniofacial surgery and IR. Many children require a tracheostomy for the first few years of life. Management is aimed at a staged debulking
7. Vascular anomalies The commonest vascular anomaly presenting in infancy is the infantile haemangioma, occurring in up to 10% of Caucasian infants. The management of these lesions has been transformed by the use of the beta blocker propanolol, which dramatically accelerates the regression of these haemangiomas. Extensive lesions causing clinical problems such as obstruction of the airway or visual axis can now be treated quickly with medication alone. Historically, IR had an occasional role
Fig. 1. Sagittal T1-weighted MRI image of a 1-week-old female with an extensive cervicofacial lymphatic malformation.
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IR operators and radiographers must employ meticulous radiation dose reduction techniques during angiography, as these can be high dose procedures. Of equal concern is the volume of contrast medium required, especially for a complex embolisation. Most operators, using non-ionic contrast medium 240 mgI/ml, will aim for a maximum dose of 4–5 ml/kg per procedure, although in reality far higher doses (up to 10 ml/kg) are often tolerated. Alongside this, saline flush volumes must be carefully monitored and the anaesthetist must be kept informed of the volumes being used. Assuming there are no acute contraindications, intravenous heparin is usually given after securing arterial access (usually 50–100 U/kg) [13]. Lesion type and morphology will dictate the embolic agent used; operators need to consider the intended outcome of embolisation (total occlusion of vascular supply or just a temporary reduction in flow) and the lesion’s flow characteristics and vascular anatomy. Embolisation choices in neonates and infants are further complicated by the need to consider the total of volume of liquid embolic that can be used and the volume of contrast needed to deliver particulate embolics. Onyx (Covidien, Plymouth MN) use is limited by the volume of associated DMSO solvent that can be tolerated. Fig. 2. Axial T2-weighted MRI image of the abdomen in a 2-week-old female with neuroblastoma stage MS. There is massive infiltration and expansion of the liver by tumour (intermediate to high signal tissue). The small volume of normal liver parenchyma (low signal tissue) is seen centrally, around the portal tracts.
of the lesion, usually by a combination of sclerotherapy and surgery. Percutaneous sclerotherapy is performed by IR, usually using simple ultrasound guidance and a range of sclerosing agents. The commonest agents available are sodium tetradecyl sulfate (STS), doxycycline, dehydrated alcohol and bleomycin. Most sclerosants cause inflammation of the cysts within the lymphatic malformation followed by chronic scarring, so that the cysts flatten and do not refill with fluid. Bleomycin has a different action, causing DNA breakage and cell destruction, and hence it is usually recommended for malformations with smaller ‘microcysts’ and more solid disease. Patients with extensive malformations, such as the child imaged in Fig. 1, will require multiple sclerotherapy and surgical procedures over several years but in experienced hands the outcomes are reasonable and most children achieve decannulation [12].
8. Angiography and embolisation Angiography and embolisation in sick neonates and infants are highly specialised procedures requiring expert paediatric IR skills [13]. Indications for embolisation include infantile or congenital haemangiomas causing cardiac failure or severe mass effect, extensive liver infiltration and associated mass effect in neuroblastoma stage MS (Fig. 2), arteriovenous shunts (including vein of Galen malformations), and bleeding. Chemoembolisation of liver tumours has also been reported. Detailed management of these conditions is beyond the scope of this paper but the general principles of arterial intervention are common to all. Arterial access is usually via the femoral vessels, as in adults, but this can be difficult in neonates with extensive liver disease in whom aortic blood flow beyond the celiac axis can be markedly reduced. The axillary arteries are a valuable alternative access route in such patients and a left axillary artery approach often gives a better angle for cannulation of the hepatic artery. In the first few days of life, umbilical artery access is often also possible. 3Fr or 4Fr vascular access sheaths are usually sufficient in calibre for most procedures.
9. Conclusion IR is a key resource in the management of sick neonates and infants. IR techniques provide fast, non-traumatic, minimally invasive options for many procedures in children and new treatments are being developed to push the boundaries of what can be achieved. IR requires the support and encouragement of specialist paediatric centres, research institutions and industry to allow it to flourish and innovate. Conflict of interest None. References [1] Nosher JL, Shami MM, Siegel RL, DeCandia M, Bodner LJ. Tunneled central venous access catheter placement in the pediatric population: comparison of radiologic and surgical results. Radiology 1994;192:265–8. [2] National Institute for Health and Care Excellence. Guidance on the use of ultrasound locating devices for placing central venous catheters TA49. London: National Institute for Health and Care Excellence; 2002. [3] Vo J, Hoffer FA, Shaw DWW. Techniques in vascular and interventional radiology: pediatric central venous access. Tech Vasc Interv Radiol 2010;13:250–7. [4] Barnacle A, Arthurs OJ, Roebuck D, Hiorns M. Malfunctioning central venous catheters in children: a diagnostic approach. Pediatr Radiol 2008;38:363–78. [5] Hogan MJ, Hoffer FA. Biopsy and drainage techniques in children. Tech Vasc Interv Radiol 2010;13:206–13. [6] Connolly B, Krishnamurthy G, Amaral J. Upper gastrointestinal access in children: techniques and outcomes. Tech Vasc Interv Radiol 2010;13:222–8. [7] Nah SA, Narayanaswarmy B, Eaton S, Coppi PD, Kiely EM, Curry JI, et al. Gastrostomy insertion in children: percutaneous endoscopic or percutaneous image-guided? J Pediatr Surg 2010;45:1153–8. [8] Ko HK, Shin JH, Song HY, Kim YJ, Ko GY, Yoon HK, et al. Balloon dilatation of anastamotic strictures secondary to surgical repair of esophageal atresia in a pediatric population: long term results. J Vasc Interv Radiol 2006;17:1327–33. [9] Roebuck DJ, Hogan MJ, Connolly B, McLaren CA. Interventions in the chest in children. Tech Vasc Interv Radiol 2011;14:8–15. [10] McLaren CA, Elliott MJ, Roebuck DJ. Tracheobronchial intervention in children. Eur J Radiol 2005;53:22–34. [11] Roebuck DJ, Sebire N, Lehmann, Barnacle A. Rapidly involuting haemangioma (RICH) of the liver. Pediatr Radiol 2012;42:308–14. [12] Cahill AM, Nijs E, Ballah D, Rabinowitz D, Thompson L, Rintoul N, et al. Percutaneous sclerotherapy in neonatal and infant head and neck lymphatic malformations: a single center experience. J Pediatr Surg 2011;46:2083–95. [13] Lord DJ, Chennapragada SM. Embolization in neonates and infants. Tech Vasc Interv Radiol 2011;14:32–41.