In situ guidance for MRI interventions using projected feedback.

PURPOSE: To develop and evaluate an augmented reality instrument guidance system for MRI-guided needle placement procedures such as musculoskeletal biopsy and arthrography. Our system guides the physician to insert a needle toward a target while looking at the insertion site without requiring special headgear. METHODS: The system is comprised of a pair of stereo cameras, a projector, and a computational unit with a touch screen. All components are designed to be used within the MRI suite (Zone 4). Multi-modality fiducial markers called VisiMARKERs, detectable in both MRI and camera images, facilitate automatic registration after the initial scan. The navigation feedback is projected directly onto the intervention site allowing the interventionalist to keep their focus on the insertion site instead of a secondary monitor which is often not in front of them. RESULTS: We evaluated the feasibility and accuracy of this system on custom-built shoulder phantoms. Two radiologists used the system to select targets and entry points on initial MRIs of these phantoms over three sessions. They performed 80 needle insertions following the projected guidance. The system targeting error was 1.09 mm, and the overall error was 2.29 mm. CONCLUSION: We demonstrated both feasibility and accuracy of this MRI navigation system. The system operated without any problems inside the MRI suite close to the MRI bore. The two radiologists were able to easily follow the guidance and place the needle close to the target without any intermediate imaging.

Catheter fragment removal from a persistent left superior vena cava in a pediatric patient.

Tunneled central venous catheters and ports provide a long-term method of delivering nutrition, hydration, or medications in children. When these devices are no longer needed, it is best practice to remove them entirely. Complications associated with having long-term venous access devices or the process of device removal include site infections, venous thrombosis or occlusion, device fracture, and possible migration of fractured fragments. We present a case of catheter fragmentation that occurred in a pediatric patient during removal of a 3-year-old left chest port that had been placed into a left superior vena cava (SVC).

Aortic quadfurcation with persistent left sciatic artery: an extremely rare anatomic variant in a 3-year-old boy.

Reports of aortoiliac variant anatomy are rare, especially in the pediatric population. A 3-year-old male patient with hypertension and left foot polydactyly with syndactyly was referred to our interventional radiology service for evaluation of a possible renovascular cause of the hypertension. Angiograms revealed an extremely rare anatomic variant consisting of the absence of the common iliac arteries bilaterally, resulting from quadfurcation of the abdominal aorta into the bilateral internal and external iliac arteries. Additionally, a persistent left sciatic artery was identified.

Minimally invasive treatment of retrocardiac tension pneumomediastinum in an extremely low birth weight infant.

A 23.4-week premature and extremely low birth weight neonate was transferred to the Neonatal Intensive Care Unit for management of respiratory failure and retrocardiac pneumomediastinum, suspected to be the result of a low tracheal injury during intubation. Initial conservative management failed and chest radiographs demonstrated worsening retrocardiac pneumomediastinum. Due to the patient's extreme low birth weight and location of the pneumomediastinum, surgery was deemed to be very high risk and potentially fatal. We report the successful definitive percutaneous management of retrocardiac tension pneumomediastinum with a minimally invasive bedside method using an intercostal paraspinal approach under the guidance of ultrasound and plain radiography.

Ultrasound-detected venous changes associated with peripheral intravenous placement in children.

HIGHLIGHTS: Ultrasound shows several venous changes in pediatric PIV-containing veins. Changes were visualized by ultrasound in the absence of physical exam findings. Venous luminal narrowing, wall thickening, and thrombosis may explain PIV failure. BACKGROUND: Peripheral intravenous catheters (PIVs) are routinely used for venous access in hospitalized pediatric patients to administer fluids and medications and to aspirate blood. Unfortunately, PIVs do not remain functional for the entire duration of intravascular need. We hypothesized that PIV malfunction may be related to venous changes that can be visualized with ultrasound (US) imaging. The purpose of this study was to describe and document such changes in pediatric patients. METHODS: This Institutional Review Board-approved study was performed at a tertiary pediatric medical center. Patients underwent US scans of their PIV-containing veins, documenting venous characteristics such as depth, diameter, wall thickness, blood flow, valves, branch points, and presence of thrombus. Patient demographics and PIV characteristics were also recorded. RESULTS: Data from 30 patients including 12 males and 18 females with a mean age of 11 years were analyzed. Mean venous depth and diameter were 2.07 ± 0.13 and 2.02 ± 0.18 mm, respectively. Mean PIV dwell time at time of evaluation was 3.3 days. PIV-associated venous changes were seen in 73% of accessed veins and included lumen narrowing (47%), wall thickening (33%), presence of thrombus (20%), and absence of blood flow around the PIV tip (40%). CONCLUSION: PIV-associated venous changes are seen with US in the majority of pediatric patients with indwelling PIVs but are not necessarily appreciated on physical exam. These changes may help explain the high rate of pediatric PIV device failure. Given the small sample size, further investigation is needed to better characterize PIV-associated venous changes in children.

Computer-assisted needle navigation for pediatric internal jugular central venous cannulation: A feasibility study.

INTRODUCTION: Vascular access for central venous catheter placement is technically challenging in children. Ultrasound guidance is recommended for pediatric central venous catheter placement, yet many practitioners rely on imprecise anatomic landmark techniques risking procedure failure due to difficulty mastering ultrasound guidance. A novel navigation system provides a visual overlay on real-time ultrasound images to depict needle trajectory and tip location during cannulation. We report the first pediatric study assessing feasibility and preliminary safety of using a computer-assisted needle navigation system to aid in central venous access. METHODS: A prospective, institutional review board-approved feasibility study was performed. All participants provided written informed consent. Ten patients (mean age: 11.4 years, five males) underwent central venous catheter placement with ultrasound and navigation system guidance. All procedures were performed by interventional radiologists expert in vascular access. Feasibility was measured through binary (yes/no) responses from participating users assessing device usability and feasibility. The number of needle passes and procedure time measures were also recorded. RESULTS: Internal jugular veins (seven right sided, three left sided) were cannulated in all patients with no complications. Users confirmed navigation system feasibility in all 10 participants. Mean vein diameter and depth was 13.3 × 9.8 ± 3.4 × 2.1 and 7.0 ± 1.7 mm, respectively. Successful cannulation occurred in all patients and required only a single needle pass in 9 of 10 patients. Mean device set-up and vascular access times were 5:31 ± 2:28 and 1:48 ± 2:35 min, respectively. CONCLUSION: This pilot study suggests that it is feasible to use a novel computer-assisted needle navigation system to safely obtain central venous access under ultrasound guidance in pediatric patients.

Percutaneous Transgluteal Ureteral Stump Access: A Novel Approach to Hybrid Management of Ureteral Stump Syndrome.

Duplicated collecting systems with minimal-to-no function of the upper moiety are often treated surgically with upper pole heminephrectomy and ureterectomy. Complications associated with the ureteral stump can occur and are collectively known as ureteral stump syndrome. We present a case of ureteral stump syndrome treated with percutaneous transgluteal access into the stump which aided in identification of an ectopic ureteral opening that could not be identified by surgical means alone.

Selective Management of Multiple Bronchopleural Fistulae in a Pediatric Patient on Extracorporeal Membrane Oxygenation: A Multidisciplinary Approach.

INTRODUCTION: This case highlights the successful utilization of a multidisciplinary approach to numerous bilateral bronchopleural fistulae (BPF) using minimally invasive techniques. In this study, we present a previously healthy 14-year-old male hospitalized with 2009 H1N1 influenza and methicillin-resistant Staphylococcus aureus coinfection complicated by severe acute respiratory distress syndrome and multifocal necrotizing pneumonia, with significant lung tissue damage requiring prolonged extracorporeal membrane oxygenation (ECMO) support. METHODS: The development of multiple BPFs precluded lung recruitment necessary to wean from ECMO. Treatment options were very limited and endobronchial valves were considered. However, localizing single airleaks with a fogarty balloon is normally the technique to determine appropriate location to place the valves. With multiple fistulae, this technique would be ineffective. Therefore, the patient was brought to interventional radiology and bronchography was performed for selective fistula mapping. With this precise localization, the multiple fistulae were ultimately controlled using image-guided embolization and the placement of multiple endobronchial valves. The success of this intervention enabled positive pressure ventilator support and rehabilitation required for weaning from ECMO support. CONCLUSION: This case highlights the successful utilization of a multidisciplinary approach to numerous bilateral BPFs using minimally invasive techniques.

Magnetic resonance imaging (MRI)-assisted laparoscopic anorectoplasty for imperforate anus: a single center experience.

PURPOSE: Surgical procedures for high imperforate anus have ranged from the posterior sagittal anorectoplasty (PSARP) to laparoscopic-assisted anorectoplasty (LAARP). PSARP bisects the sphincter muscle complex, introducing muscle injury and scarring. LAARP uses a straight trocar to traverse an often non-linear sphincter muscle complex. MRI-assisted LAARP (MRI-LAARP) guides the neorectum precisely through the middle of the entire sphincter complex along its trajectory. We present our experience utilizing MRI intraoperatively during LAARP. METHODS/PROCEDURE: Ten children underwent MRI-LAARP procedures. Intraoperative MRI was performed to delineate the sphincter complex, and to guide the advancement of an MRI-compatible needle through the center of the complex from skin to the peritoneal cavity. The remainder of the procedure was completed using the standard LAARP technique. RESULTS: All had successful MRI needle placement through the sphincter complex. Nine patients had successful laparoscopic pull-through procedures; one was converted to open due to severe intraperitoneal adhesions. Postoperative stay averaged 5.4 ± 4.4 days. Out of the ten patients, one child had mild dehiscence of the anal anastomosis requiring revision 11 days postoperatively. CONCLUSION: The theoretical advantage of the MRI-LAARP is placing the neorectum through the entire sphincter complex without transecting the muscle. Follow-up of these patients shows good short-term results; however, long-term follow-up will be needed to best assess sphincter and bowel function.

Image-guided percutaneous core needle biopsy of soft-tissue masses in the pediatric population.

BACKGROUND: A paucity of literature describes the use of imaged-guided percutaneous core needle biopsy for the diagnosis and characterization of pediatric soft-tissue masses and lesions. OBJECTIVE: To retrospectively determine whether image-guided percutaneous core needle biopsy is adequate for diagnosing and characterizing benign and malignant pediatric soft-tissue masses and lesions. MATERIALS AND METHODS: We identified children (≤18 years old) who underwent US- or CT-guided percutaneous core needle biopsy of a soft-tissue mass or other lesion between January 2012 and March 2014. Using medical records, we documented the following data: age and gender, site of the mass or lesion, size and number of biopsy specimens, whether the biopsy procedure was diagnostic, whether sufficient tissue was obtained for necessary ancillary testing (e.g., cytogenetic evaluation), and whether there was a procedural complication within 1 week. RESULTS: One hundred eight soft-tissue masses or lesions were biopsied under imaging guidance in 84 children; 39 (46%) were girls. Mean age ± standard deviation (SD) was 12.1 ± 5.1 years (range 6 months to 18 years). Of these procedures, 105/108 (97%) were diagnostic; 82/108 (76%) were US-guided; 87/108 (81%) were performed using a 17-gauge introducer needle/18-gauge biopsy instrument. The mean number ± SD of core needle biopsy specimens obtained was 8.9 ± 5.0. For newly diagnosed malignancies, adequate tissue was obtained for ancillary testing in 28/30 (93%) masses. One minor complication was documented. CONCLUSION: Image-guided percutaneous core needle biopsy of pediatric soft-tissue masses is safe, has a high diagnostic rate, and provides sufficient tissue for ancillary testing.

Ultrasound-guided fine-needle aspiration biopsy of pediatric thyroid nodules.

BACKGROUND: The role of US-guided fine-needle aspiration biopsy (US-FNAB) of thyroid nodules is not well-established in children. OBJECTIVE: To retrospectively assess the utility of US-FNAB of pediatric thyroid nodules. MATERIALS AND METHODS: We reviewed Department of Radiology records to identify children who underwent US-FNAB of the thyroid between 2005 and 2013. Two board-certified pediatric radiologists reviewed pre-procedural thyroid US exams and documented findings by consensus. We recorded cytopathology findings and compared them to surgical pathology diagnoses if the nodule was resected. We also recorded demographic information, use of sedation or general anesthesia, and presence of on-site cytopathological feedback. The Student's t-test was used to compare continuous data; the Fisher exact test was used to compare proportions. RESULTS: US-FNAB was conducted on a total of 86 thyroid nodules in 70 children; 56 were girls (80%). Seventy-eight of the 86 (90.7%) US-FNAB procedures were diagnostic; 69/78 (88.5%) diagnostic specimens were benign (including six indeterminate follicular lesions that were proved at surgery to be benign) and 9/78 (11.5%) were malignant/suspicious for malignancy (all proved to be papillary carcinomas). There was no difference in size of benign vs. malignant lesions (P = 0.82) or diagnostic vs. non-diagnostic lesions (P = 0.87). Gender (P = 0.19), use of sedation/general anesthesia (P = 0.99), and presence of onsite cytopathological feedback (P = 0.99) did not affect diagnostic adequacy. Microcalcifications (P < 0.0001; odds ratio [OR] = 113.7) and coarse calcifications (P = 0.03; OR = 19.4) were associated with malignancy. Diagnoses at cytopathology and surgical pathology were concordant in 27/29 (93.1%) nodules; no US-FNAB procedure yielded false-positive or false-negative results for malignancy. CONCLUSION: US-FNAB of pediatric thyroid nodules is feasible, allows diagnostic cytopathological evaluation, and correlates with surgical pathology results in resected nodules.

Development of an operative suspension system for the performance of MRI-OR-guided laparoscopic anoplasty.

BACKGROUND: MRI-guided laparoscopic assisted anorectoplasty (MRI-LAARP), a new approach for surgical correction of high imperforate anus, does not bisect the sphincter complex as in the PSARP and is able to pull the neorectum through the entire sphincter complex unlike the LAARP. There is no available MRI-compatible device to position and transport patients during this procedure. We report on the design of such a device here. METHODS AND DEVICE: The device was constructed from 1.0″ polyvinylchloride tubing and poly-methyl methacrylate (Plexiglass(®)) platform. The device has a stable, rigid base on which platform is secure. An adjustable and removable superstructure is secured to this base to suspend legs for lithotomy position. RESULTS: MRI-LAARP has been performed on 6 patients. The device has performed well and meets requirements set forth in development including construction with MRI-compatible materials, size fitting in the MRI bore, ability to hold patient in lithotomy position, ability to position and support MRI flex coils, and providing stability while transporting to a separate OR with needle in position. CONCLUSIONS: This device provides a stable structure to position and transport a patient with a needle in a tenuous position without dislodgement allowing this procedure, and potentially other procedures, to be done in hospitals without MROR capability.

Endovascular treatment of thrombosed inferior vena cava filters: Techniques and short-term outcomes.

PURPOSE: To present the techniques for endovascular treatment of thrombosed filter-bearing inferior vena cavae (IVCs), along with short-term clinical and imaging follow-up. MATERIALS AND METHODS: A total of 45 consecutive patients (17 females and 28 males), aged 19-79 years (mean age of 49 years), who had IVC filter placement complicated by symptomatic acute or chronic iliocaval thrombosis and underwent endovascular therapy were studied. All patients presented with lower extremity swelling and/or pain. One patient also had bilateral lower extremity swelling and chronic gastrointestinal (GI) bleeding which was secondary to chronic systemic to portal venous collaterals. Patients underwent one or more of the following endovascular treatments depending on the chronicity and extent of thrombosis: (a) catheter-directed thrombolysis (CDT) (n = 25), (b) pharmacomechanical thrombolysis (PMT) (n = 15), (c) balloon angioplasty (n = 45), and/or (d) stent placement across the filter (n = 42). In addition, 16 patients underwent groin arteriovenous fistula (AVF) creation (36%) and 3 (7%) had femoral venous thrombectomy to improve flow in the recanalized iliac veins and IVCs. RESULTS: Anatomical success was achieved in all patients. Follow-up was not available in 10 patients (lost to follow-up, n = 4; expired due to comorbidities, n = 2; lost to follow-up after re-intervention, n = 4). At a mean follow-up time of 13.3 months (range 1-48 months), clinical success was achieved in 27 patients (60%), i.e. in 21 patients without re-intervention and in 6 patients with re-intervention. Clinical success was not achieved despite re-intervention in eight patients. Higher clinical success was noted in patients who did not require repeat interventions (P = 0.03) and the time to re-intervention was significantly shorter in patients who had clinical failure (P = 0.01). AVF creation did not improve the clinical success rate (P = 1). There was no significant difference in clinical success between patients who had acute or subacute thrombosis compared to those who had chronically occluded filter-bearing IVCs (P = 1). CONCLUSION: This study suggests that endovascular therapy for thrombosed filter-bearing IVCs is safe and technically feasible.

Preoperative splenic artery embolization in klippel-Trenaunay syndrome with massive splenomegaly: A case report.

The authors describe a case of Klippel-Trenaunay syndrome (KTS) with massive splenomegaly in a 29-year-old woman. Preoperative splenic artery embolization using the "double embolization technique" (a combination of distal selective splenic artery embolization and proximal splenic artery occlusion) facilitated open splenectomy.

Magnetic resonance angiography of the pediatric abdomen and pelvis: techniques and imaging findings.

Although traditional catheter-based angiography has been the gold standard for pediatric abdominal and pelvic vascular imaging for the past several decades, advances in magnetic resonance angiography (MRA) have made it a viable alternative. MRA offers several advantages in that it is noninvasive, can be performed without ionizing radiation, and does not necessarily rely on contrast administration. The ability of modern MRA techniques to define variant vascular anatomy and detect vascular disease may obviate traditional angiography in some patients.

Imaging of renin-mediated hypertension in children.

OBJECTIVE: The purpose of this article is to review the imaging findings of common and uncommon causes of renin-mediated hypertension in children using a multimodality radiologic approach. CONCLUSION: Pediatric hypertension, although uncommon, is often due to aortic or renal artery narrowing. Imaging plays an important role in the diagnosis and characterization of pediatric renin-mediated causes of hypertension.

Interventional therapies for hepatocellular carcinoma.

Hepatocellular carcinoma is the third most common cause of cancer-related death. In the past few years, staging systems have been developed that enable patients to be stratified into treatment algorithms in a multidisciplinary setting. Several of these treatments involve minimally invasive image-guided therapy that can be performed by radiologists.

Temporary placement of stent grafts in postsurgical benign biliary strictures: a single center experience.

OBJECTIVE: To evaluate the effect of temporary stent graft placement in the treatment of benign anastomotic biliary strictures. MATERIALS AND METHODS: Nine patients, five women and four men, 22-64 years old (mean, 47.5 years), with chronic benign biliary anastomotic strictures, refractory to repeated balloon dilations, were treated by prolonged, temporary placement of stent-grafts. Four patients had strictures following a liver transplantation; three of them in bilio-enteric anastomoses and one in a choledocho-choledochostomy. Four of the other five patients had strictures at bilio-enteric anastomoses, which developed after complications following laparoscopic cholecystectomies and in one after a Whipple procedure for duodenal carcinoma. In eight patients, balloon-expandable stent-grafts were placed and one patient was treated by insertion of a self-expanding stent-graft. RESULTS: In the transplant group, treatment of patients with bilio-enteric anastomoses was unsuccessful (mean stent duration, 30 days). The patient treated for stenosis in the choledocho-choledochostomy responded well to consecutive self-expanding stent-graft placement (total placement duration, 112 days). All patients with bilio-enteric anastomoses in the non-transplant group were treated successfully with stent-grafts (mean placement duration, 37 days). CONCLUSION: Treatment of benign biliary strictures with temporary placement of stent-grafts has a positive effect, but is less successful in patients with strictures developed following a liver transplant.

Acute Renal Artery Occlusion with Prolonged Renal Ischemia: A Case of Successful Treatment with Stent Placement and Catheter-directed Thrombolysis.

We present a case of acute renal artery occlusion caused by a high-grade stenosis associated with in-situ thrombosis. Endovascular renal artery stent placement combined with catheter-directed thrombolysis reversed the renal ischemia with restoration of renal function despite the prolonged ischemia.

The normal distribution of thoracoabdominal aorta small branch artery ostia.

The purpose of this study was to determine the normal distribution of aortic branch artery ostia. CT scans of 100 subjects were retrospectively reviewed. The angular distributions of the aorta with respect to the center of the T3 to L4 vertebral bodies, and of branch artery origins with respect to the center of the aorta were measured. At each vertebral body level the distribution of intercostal/lumbar arteries and other branch arteries were calculated. The proximal descending aorta is posteriorly placed becoming a midline structure, at the thoracolumbar junction, and remains anterior to the vertebral bodies within the abdomen. The intercostal and lumbar artery ostia have a distinct distribution. At each vertebral level from T3 caudally, one intercostal artery originates from the posterior wall of the aorta throughout the thoracic aorta, while the other intercostal artery originates from the medial wall of the descending thoracic aorta high in the chest, posteromedially from the mid-thoracic aorta, and from the posterior wall of the aorta low in the chest. Mediastinal branches of the thoracic aorta originate from the medial and anterior wall. Lumbar branches originate only from the posterior wall of the abdominal aorta. Aortic branch artery origins arise with a bimodal distribution and have a characteristic location. Mediastinal branches of the thoracic aorta originate from the medial and anterior wall. Knowing the location of aortic branch artery ostia may help distinguish branch artery pseudoaneurysms from penetrating ulcers.