Thoracic duct drainage patterns in heterotaxy.

BACKGROUND: Disordered lymphatic drainage is common in congenital heart diseases (CHD), but thoracic duct (TD) drainage patterns in heterotaxy have not been described in detail. This study sought to describe terminal TD sidedness in heterotaxy and its associations with other anatomic variables. METHODS: This was a retrospective, single-center study of patients with heterotaxy who underwent cardiovascular magnetic resonance imaging at a single center between July 1, 2019 and May 15, 2023. Patients with (1) asplenia (right isomerism), (2) polysplenia (left isomerism) and (3) pulmonary/abdominal situs inversus (PASI) plus CHD were included. Terminal TD sidedness was described as left-sided, right-sided, or bilateral. RESULTS: Of 115 eligible patients, the terminal TD was visualized in 56 (49 %). The terminal TD was left-sided in 25 patients, right-sided in 29, and bilateral in two. On univariate analysis, terminal TD sidedness was associated with atrial situs (p = 0.006), abdominal situs (p = 0.042), type of heterotaxy (p = 0.036), the presence of pulmonary obstruction (p = 0.041), superior vena cava sidedness (p = 0.005), and arch sidedness (p < 0.001). On multivariable analysis, only superior vena cava and aortic arch sidedness were independently associated with terminal TD sidedness. CONCLUSIONS: Terminal TD sidedness is highly variable in patients with heterotaxy. Superior vena cava and arch sidedness are independently associated with terminal TD sidedness. Type of heterotaxy was not independently associated with terminal TD sidedness. This data improves the understanding of anatomic variation in patients with heterotaxy and may be useful for planning for lymphatic interventions.

Magnetic resonance three-dimensional steady-state free precession imaging of the thoracic duct in patients with Fontan circulation and its relationship to outcomes.

BACKGROUND: Lymphatic complications are common in patients with Fontan circulation. Three-dimensional balanced steady-state free precession (3D bSSFP) angiography by cardiovascular magnetic resonance (CMR) is widely used for cardiovascular anatomical assessment. We sought to determine the frequency of thoracic duct (TD) visualization using 3D bSSFP images and assess whether TD characteristics are associated with clinical outcomes. METHODS: This was a retrospective, single-center study of patients with Fontan circulation who underwent CMR. Frequency matching of age at CMR was used to construct a comparison group of patients with repaired tetralogy of Fallot (rTOF). TD characteristics included maximum diameter and a qualitative assessment of tortuosity. Clinical outcomes included protein-losing enteropathy (PLE), plastic bronchitis, listing for heart transplantation, and death. A composite outcome was defined as presence of any of these events. RESULTS: The study included 189 Fontan patients (median age 16.1 years, IQR 11.0-23.2 years) and 36 rTOF patients (median age 15.7 years, IQR 11.1-23.7 years). The TD diameter was larger (median 2.50 vs. 1.95 mm, p = 0.002) and more often well visualized (65% vs. 22%, p < 0.001) in Fontan patients vs. rTOF patients. TD dimension increased mildly with age in Fontan patients, R = 0.19, p = 0.01. In Fontan patients, the TD diameter was larger in those with PLE vs. without PLE (age-adjusted mean 4.11 vs. 2.72, p = 0.005), and was more tortuous in those with NYHA class ≥ II vs. class I (moderate or greater tortuosity 75% vs. 28.5%, p = 0.02). Larger TD diameter was associated with a lower ventricular ejection fraction that was independent of age (partial correlation = - 0.22, p = 0.02). More tortuous TDs had a higher end-systolic volume (mean 70.0 mL/m2 vs. 57.3 mL/m2, p = 0.03), lower creatinine (mean 0.61 mg/dL vs. 0.70 mg/dL, p = 0.04), and a higher absolute lymphocyte count (mean 1.80 K cells/µL vs. 0.76 K cells/µL, p = 0.003). The composite outcome was present in 6% of Fontan patients and was not associated with TD diameter (p = 0.50) or tortuosity (p = 0.09). CONCLUSIONS: The TD is well visualized in two-thirds of patients with Fontan circulation on 3D-bSSFP images. Larger TD diameter is associated with PLE and increased TD tortuosity is associated with an NYHA class ≥ II.

Imaging of pediatric extremity soft tissue tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

Pediatric soft tissue tumors of the extremity include rhabdomyosarcoma and nonrhabdomyosarcoma neoplasms. This manuscript provides consensus-based imaging recommendations for imaging evaluation at diagnosis, during treatment, and following completion of therapy for patients with a soft tissue tumor of the extremity.

Imaging of pediatric liver tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper.

Primary hepatic malignancies are relatively rare in the pediatric population, accounting for approximately 1%-2% of all pediatric tumors. Hepatoblastoma and hepatocellular carcinoma are the most common primary liver malignancies in children under the age of 5 years and over the age of 10 years, respectively. This paper provides consensus-based imaging recommendations for evaluation of patients with primary hepatic malignancies at diagnosis and follow-up during and after therapy.

The Use of an Inflatable Adhesive External Compression Device for Maintenance of Hemostasis following Angiography in Children.

PURPOSE: To assess the safety and efficacy of the posthemostasis use of an inflatable adhesive external compression device (SafeGuard) following angiography in children performed under general anesthesia. MATERIALS AND METHODS: Medical records of 74 children (43 females) with a mean age of 8.9 years (range, 0.4-18.0 years) and mean weight of 44.0 kg (range, 7.3-115.7 kg) in whom an inflatable adhesive external compression device was used for maintaining hemostasis following angiography under general anesthesia were retrospectively reviewed. After establishing hemostasis with manual compression, the device was applied and inflated over the arteriotomy. The patients were assessed for access-related adverse events in the recovery unit and during postprocedural follow-up. RESULTS: The inflatable adhesive external compression device was utilized to maintain hemostasis following 181 angiography procedures. The mean length of the procedure was 396 minutes. The common femoral artery (n = 170, 93.9%) was the most common access, using 4-5-F vascular sheath (n = 118, 65.2%) or 3-5-F sheathless (n = 8, 12.7%) catheters. The mean time to deflation was 93 minutes. There were no adverse events other than minor bleeding from the arteriotomy after deflation (n = 2, 1.1%) and early deflation of the device because of pain (n = 1, <1%). Follow-up ultrasonography (n = 109 procedures, 60.2% at a mean follow-up of 2.2 years) demonstrated patency of the access artery. CONCLUSIONS: The use of an inflatable adhesive external compression device following angiography in children to maintain hemostasis during the emergence phase of anesthesia and recovery period is safe and effective. The use of this simple device may reduce the need for postprocedural sedation and facilitate early discharge.

Appendix to the Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image-Guided Interventions: Pediatric Considerations.

PURPOSE: To provide guidance on the use of anticoagulant and antithrombotic agents in pediatric patients undergoing interventional radiology procedures. MATERIALS AND METHODS: A multidisciplinary writing group conducted a comprehensive literature search to identify studies on the topic of interest. Recommendations were developed for procedural risk and medication dosage and withholding. A modified Delphi technique was used to achieve consensus agreement on the recommendations. RESULTS: A total of 24 studies, including systematic reviews and meta-analyses, randomized controlled trials, and prospective and retrospective cohort studies, were identified as relevant. The expert writing group agreed on procedural risk categorization, laboratory testing thresholds, and medication dosage and withholding recommendations specific to pediatric practice. They additionally described the nuances of anticoagulation in clinical conditions specific to pediatrics. CONCLUSIONS: The Society of Interventional Radiology recommends following the guidance provided in the document when developing multidisciplinary management protocols for anticoagulation and antithrombotic treatment in pediatric patients undergoing interventional radiology procedures.

Qualitative evaluation of MRI features in aneurysmal bone cysts after percutaneous sclerotherapy.

OBJECTIVE: To report MRI findings of changes seen in aneurysmal bone cysts after percutaneous sclerotherapy treatment. MATERIALS AND METHODS: After applying exclusion criteria, a total of 36 patients who had aneurysmal bone cysts and undergone percutaneous sclerotherapy were included in this study. The pre-treatment and post-treatment MRIs were reviewed and multiple pre-determined MRI findings were evaluated. The presence of each post-treatment finding, as well as the time for each finding to develop, was recorded. RESULTS: Early post-sclerotherapy changes include increased perilesional edema and enhancement, which appear on MRI on average 5.1 months after the initial sclerotherapy. This is followed by decreased cystic areas, which can be seen on average 5.9 months after the initial treatment. The presence of fibrosis, improved cortical integrity, and improving mass effect are later post-treatment changes and appear on MRI on average 9.7 months, 10.6 months, and 16.1 months after the initial sclerotherapy, respectively. CONCLUSION: The early and late post-sclerotherapy MR findings of aneurysmal bone cysts were reported in this study.

Making the most of small samples: Optimization of tissue allocation of pediatric solid tumors for clinical and research use.

INTRODUCTION: Tissue from pediatric solid tumors is in high demand for use in high-impact research studies, making the allocation of tissue from an anatomic pathology laboratory challenging. We designed, implemented, and assessed an interdepartmental process to optimize tissue allocation of pediatric solid tumors for both clinical care and research. METHODS: Oncologists, pathologists, surgeons, interventional radiologists, pathology technical staff, and clinical research coordinators participated in the workflow design. Procedures were created to address patient identification and consent, prioritization of protocols, electronic communication of requests, tissue preparation, and distribution. Pathologists were surveyed about the value of the new workflow. RESULTS: Over a 5-year period, 644 pediatric solid tumor patients consented to one or more studies requesting archival or fresh tissue. Patients had a variety of tumor types, with many rare and singular diagnoses. Sixty-seven percent of 1768 research requests were fulfilled. Requests for archival tissue were fulfilled at a significantly higher rate than those for fresh tissue (P > .001), and requests from resection specimens were fulfilled at a significantly higher rate than those from biopsies (P > .0001). In an anonymous survey, seven of seven pathologists reported that the process had improved since the introduction of the electronic communication model. CONCLUSIONS: A collaborative and informed model for tissue allocation is successful in distributing archival and fresh tissue for clinical research studies. Our workflows and policies have gained pathologists' approval and streamlined our processes. As clinical and research programs evolve, a thoughtful tissue allocation process will facilitate ongoing research.

Two-hour Observation After Liver Biopsy in Children: Clinical and Economic Outcome of a Quality Improvement Intervention.

OBJECTIVE: Following percutaneous liver biopsy performed at our institution on an outpatient basis, children traditionally were observed for 4 hours then discharged after verifying a stable hematocrit level. In June 2015, we adopted a quality improvement project with shorter 2-hour observation for patients with no known risks and the hematocrit test was abandoned.The purpose of this study is to evaluate the clinical and economic outcomes of early discharge of children following liver biopsy. METHODS: We analyzed data on 2 groups of children who underwent ultrasound-guided nontargeted core needle liver biopsy performed on outpatient basis. Group A (100 procedures with 4-hour postprocedural observation time and hematocrit test) was compared with group B (100 procedures with 2-hour observation without hematocrit test). RESULTS: Group A consisted of 92 patients (43 boys; 49 girls) with a mean age of 11.1 years and mean weight of 52.6 kg. Group B had 92 patients (47 boys; 45 girls) with a mean age of 8.9 years and mean weight of 40.5 kg. The mean length of observation was 281 minutes (range 204-540 minutes) and 147 minutes (range 86-332 minutes) for groups A and B, respectively. The mean recovery charges were reduced by 35% per procedure in group B. The tissue obtained was sufficient for pathologic diagnosis in all procedures. There were no biopsy-related complications in either group. CONCLUSIONS: Enhanced recovery with early discharge of low-risk children after 2-hour observation following percutaneous liver biopsy can be safely implemented without adversely affecting the outcome. Shorter postbiopsy observation can be cost-saving and may potentially improve patient satisfaction.

Clinical and imaging features in fibro-adipose vascular anomaly (FAVA).

BACKGROUND: Fibro-adipose vascular anomaly (FAVA) is a rare and recently described complex vascular malformation. The clinical and imaging features and morphology can be confusing and often overlap with features of other vascular malformations and tumors. OBJECTIVE: To present the imaging characterization of FAVA in association with clinical features. MATERIALS AND METHODS: We retrospectively evaluated clinical and imaging (MRI, sonography and venography) findings in FAVA. We documented the clinical presentation, lesion morphology, imaging characteristics, tissue distribution, pattern of contrast enhancement and vascular characteristics. RESULTS: Thirty-eight people (31 female, 7 male) ages 1-30 years (mean 12 years) were diagnosed with FAVA based on clinical findings combined with imaging or histopathological findings (n=17). Most lesions were in the lower extremity (n=36). Three patterns were noticed: focal, focal infiltrative and diffuse. CONCLUSION: Fibro-adipose vascular anomaly, a rare and complex vascular malformation, has distinct clinical and imaging features that a radiologist should be familiar with to avoid delay in diagnosis and to direct appropriate management.

Surgical Management of Fibroadipose Vascular Anomaly of the Lower Extremities.

BACKGROUND: Fibroadipose vascular anomaly (FAVA) is a recently-defined vascular malformation often involving the extremities and presenting in childhood. Patients may present to orthopaedic surgeons with pain, swelling, joint contractures, and leg length discrepancy. There is no established therapy or treatment paradigm. We report on outcomes following surgical excision for patients with this condition. METHODS: Between 2007 and 2016, all 35 patients that underwent excision of lower-extremity FAVA were retrospectively reviewed using a combination of medical records, radiologic findings, and telemedicine reviews. RESULTS: Mean age at initial presentation was 12.3±6.8 years. Mean follow-up from time of definitive diagnosis at our institution was 66 months (range: 12 to 161 mo). Mean follow-up after surgery was 35 months (range: 6 to 138 mo). Females were affected more than males (71% vs. 29%). The most common location of FAVA was in the calf (49%), followed by the thigh (40%). The most commonly involved muscle was gastrocnemius (29%), followed by the quadriceps (26%). At latest follow-up after surgery, there was an improvement in the proportion of patients with pain at rest (63% vs. 29%), pain with activity (100% vs. 60%), as well as analgesia use (94% vs. 37%). Fourteen patients (40%) had symptomatic residual disease or recurrence of FAVA requiring further treatment. Six patients (17%) required further surgery and 6 (17%) required further interventional radiologic procedures. Three patients (9%) required eventual amputation for intractable pain and loss of function. Lesions with direct nerve involvement were associated with persistent neuropathic symptoms at latest follow-up (P=0.002) as well as symptomatic residual disease and/or recurrence requiring further treatment (P=0.01). Seventeen patients (49%) had 19 preoperative joint contractures. Eighteen of the 19 contractures (95%) had sustained improvement at latest follow-up. CONCLUSIONS: In carefully selected patients, surgical excision of FAVA results in improvement of symptoms. However, symptomatic residual disease and/or recurrence are not uncommon. Direct nerve involvement is associated with a worse outcome. LEVEL OF EVIDENCE: Level IV-case series.

Characterization of long-term outcomes for pediatric patients with epithelioid hemangioma.

Epithelioid hemangioma (EH) is a rare benign vascular tumor that occurs in soft tissues and bone and presents between the third and sixth decades of life. Little is known about the clinical course and outcomes of pediatric EH. We report 11 patients diagnosed with EH at a median age of 14.4 years. One patient treated with interferon and one with sirolimus exhibited partial response for >2 years. Although a benign neoplasm, EH is difficult to manage without standard protocols and portends considerable morbidity. Our findings suggest medical management, particularly sirolimus, may benefit these patients; however, long-term follow-up is needed.

Catheter-Directed Thrombolysis in a Child with Bilateral Renal Artery Graft Thrombosis.

A 5-year-old boy with midaortic syndrome who had undergone aortic bypass and bilateral renal artery grafts presented to the emergency department 1 year after surgery with symptoms of nausea, vomiting, and abdominal pain. Because of delay in diagnosis of bilateral renal artery thrombosis, his condition progressed to anuric renal failure. He underwent catheter-directed thrombolysis 7 days after presentation with administration of tissue plasminogen activator and heparin infusion over a 24-hour period. There was successful resolution of thrombus and complete recovery of renal function to baseline. The patient had normal renal function at 6-month follow-up.

Cryoablation in fibro-adipose vascular anomaly (FAVA): a minimally invasive treatment option.

BACKGROUND: Fibro-adipose vascular anomaly (FAVA) is a complex vascular malformation that typically presents with persistent pain, discomfort, contracture and other disabling symptoms. There are no minimally invasive treatment options to effectively control these symptoms. Image-guided percutaneous cryoablation, which has been used to control pain in people with cancer, could be used for similar indications in FAVA. OBJECTIVE: To assess the role of image-guided percutaneous cryoablation for control of symptoms in FAVA lesions. MATERIALS AND METHODS: We conducted a retrospective cohort study of 20 children and young adults with FAVA who underwent percutaneous cryoablation at 26 sites, from September 2013 to August 2015. The outcome was based on the brief pain inventory scoring (BPI), concurrent symptoms, clinical response and patient satisfaction. RESULTS: After cryoablation there was significant improvement in pain, which dropped by 3 points (pain now) to 3.7 points (pain in the last 24 h). Most patients indicated that pain interfered less in their everyday social life. Concurrent symptoms like swelling, physical limitations and skin hyperesthesia also improved. Clinical response was greatest at 2-5 months follow-up after cryoablation, with acceptable patient satisfaction thereafter. Technical response was 100%. There were no major complications. CONCLUSION: Image-guided percutaneous cryoablation is a safe and effective option for treatment of symptomatic FAVA lesions.

Imaging features of kaposiform lymphangiomatosis.

BACKGROUND: Kaposiform lymphangiomatosis is a rare, aggressive lymphatic disorder. The imaging and presenting features of kaposiform lymphangiomatosis can overlap with those of central conducting lymphatic anomaly and generalized lymphatic anomaly. OBJECTIVE: To analyze the imaging findings of kaposiform lymphangiomatosis disorder and highlight features most suggestive of this diagnosis. MATERIALS AND METHODS: We retrospectively identified and characterized 20 children and young adults with histopathological diagnosis of kaposiform lymphangiomatosis and radiologic imaging referred to the vascular anomalies center between 1995 and 2015. RESULTS: The median age at onset was 6.5 years (range 3 months to 27 years). The most common presenting features were respiratory compromise (dyspnea, cough, chest pain; 55.5%), swelling/mass (25%), bleeding (15%) and fracture (5%). The thoracic cavity was involved in all patients; all patients had mediastinal involvement followed by lung parenchymal disease (90%) and pleural (85%) and pericardial (50%) effusions. The most common extra-thoracic sites of disease were the retroperitoneum (80%), bone (60%), abdominal viscera (55%) and muscles (45%). There was characteristic enhancing and infiltrative soft-tissue thickening in the mediastinum and retroperitoneum extending along the lymphatic distribution. CONCLUSION: Kaposiform lymphangiomatosis has overlapping imaging features with central conducting lymphatic anomaly and generalized lymphatic anomaly. Presence of mediastinal or retroperitoneal enhancing and infiltrative soft-tissue disease along the lymphatic distribution, hemorrhagic effusions and moderate thrombocytopenia (50-100,000/µl) should favor diagnosis of kaposiform lymphangiomatosis.

Predictors of diagnostic success in image-guided pediatric soft-tissue biopsies.

BACKGROUND: Image-guided percutaneous core needle biopsy (PCNB) of soft-tissue lesions is a minimally invasive technique that can provide a definitive diagnosis for treatment. Anatomical and age considerations in children require judicious use of safe percutaneous biopsy techniques. There are, however, limited data on the determinants of diagnostic yield in soft-tissue lesions in this population. OBJECTIVES: To assess lesion-related and technical factors that affect diagnostic yield and safety in PCNB of pediatric soft-tissue lesions. MATERIALS AND METHODS: This was a retrospective cohort study of 205 PCNB performed from January 2000 to July 2014. Diagnostic yield and its associations with technical and lesion-related factors were evaluated using bivariate analysis. RESULTS: The mean patient age was 11.1 ± 6.9 years (interquartile range [IQR]: 4.3-16 years). Ultrasound guidance alone was used in 91% of cases. The mean number of passes was 7.5 ± 3.2 (IQR: 5-9 passes) per case. The overall diagnostic yield was 75% and the overall accuracy was 88%. Performing fewer than four passes was associated with a nondiagnostic biopsy (P = 0.001). There were no lesion or other technical factors that predicted a diagnostic biopsy. There were two complications (1%) over 14 years. CONCLUSION: Image-guided PCNB is a safe and effective means for the diagnosis of pediatric soft-tissue abnormalities. Aside from performing at least four passes, our data show no technical or lesion-related factors that increase diagnostic yield in pediatric PCNB of soft-tissue lesions.

Percutaneous coil embolization of massive pelvic pseudoaneurysm in an infant.

Iatrogenic pseudoaneurysm formation is an uncommon but potentially serious complication of cardiac catheterization. This case report describes diagnosis and treatment of a large left external iliac artery pseudoaneurysm in a 3-month-old boy following cardiac catheterization and aortic balloon dilatation for aortic coarctation. A 4-cm pulsatile mass in the left hemipelvis was discovered on MRI performed 6 weeks later for possible tethered spinal cord. Sonography and angiography showed a large pseudoaneurysm of the left external iliac artery just distal to the iliac bifurcation with no flow in the external iliac artery distal to the pseudoaneurysm. Percutaneous US-guided thrombin injection was performed twice, with partial recanalization after each treatment. The residual portion of the pseudoaneurysm was then successfully embolized with percutaneous coils deployed under US and fluoroscopic guidance.

Subfascial involvement in glomuvenous malformation.

OBJECTIVE: Glomuvenous malformation (GVM) is an inherited autosomal dominant trait. The lesions, which appear as bluish nodules or plaque-like cutaneous elevations, are usually tender and more firm than sporadic venous malformations. Conventionally, the lesions are thought to be limited to the cutaneous and subcutaneous tissue planes. The objective was to characterize the depth of involvement of GVM lesions. MATERIALS AND METHODS: Magnetic resonance imaging (MRI) findings in GVM were retrospectively evaluated by two radiologists. The signal characteristics, tissue distribution, pattern of contrast enhancement of the lesions in GVM were documented. RESULTS: Thirty patients (19 female) aged 1-35 years (mean 18 years) were diagnosed with GVM based on clinical features (n = 20) and/or histopathological findings (n = 10). The lesions were present in the lower extremity (n = 15), upper extremity (n = 6), cervico-facial region (n = 6), pelvis (n = 2), and chest wall (n = 1). All patients had skin and subcutaneous lesions. Fifty percent of the patients (n = 15) demonstrated subfascial intramuscular (n = 15), intra-osseous (n = 1), and intra-articular involvement (n = 1). CONCLUSION: Contrary to the conventional belief that GVMs are generally limited to the skin and subcutaneous tissue, deep subfascial extension of the lesions is common.

Image-Guided Transrectal Drainage of Pelvic Abscesses in Children.

OBJECTIVE: To describe our technique and share our experience with image-guided transrectal drainage (TRD) of pelvic abscesses in children. MATERIALS AND METHODS: Retrospective review and analysis of indications for image-guided TRD and examination of procedural outcomes in pediatric patients with pelvic abscesses over 8 years. RESULTS: A total of 69 patients (33 males and 36 females) with symptomatic pelvic abscesses underwent image-guided TRD. The median age and weight of the patients were 11.5 years (range, 3-18) and 46.8 kg (range, 15.1-118.0), respectively. The etiologies of the pelvic abscesses were perforated appendicitis (72.5%) and post-operative collections (27.5%). All patients presented with abdominal pain. Fever, emesis, and diarrhea were also common symptoms. The size of the pelvic abscesses ranged from 24.0 to 937.1 mL (median, 132.7). Technical success was achieved in 68 of 69 TRD procedures (98.6%). Clinical improvement was observed in all patients with technically successful TRD. The TRD catheter dwell time ranged from 0 to 10 days (median, 4.0). Most patients who underwent TRD for perforated appendicitis subsequently underwent elective appendectomy after the resolution of the pelvic abscess (84.0%). The median time from TRD to elective appendectomy was 2.8 months (range, 0.3-6.1). There were no procedure-related complications. CONCLUSION: Image-guided TRD is a safe and effective procedure with high technical and clinical success rates for the treatment of pelvic abscesses in children.

Transjugular retrograde cannulation of the portal vein via patent ductus venosus: alternative access for endovascular hepatic interventions.

The use of the patent ductus venosus via a transjugular approach to access the portal system for endovascular treatment of hepatic vascular anomalies in three infants is reported. Two patients had an arterioportal fistula, and one had a rapidly involuting congenital hemangioma. All patients underwent arteriography followed by embolization of the vascular anomalies without complications. This alternative route is technically simpler and likely safer than transarterial and transhepatic approaches.