Daniel Ashton

Body MR angiography in children: how we do it

Vascular pathology is ubiquitous in children. Common indications for angiographic imaging in the body include congenital anomalies, portal hypertension, assessing resectability of neoplasms, renovascular hypertension, vascular malformations, vasculitis, systemic vein thrombosis, and trauma. MR angiography, with or without the use of intravenous contrast agents, is therefore a mainstay in the repertoire of MR imaging in children. Pediatric contrast-enhanced MR angiography has benefited from several innovations in recent years, including improved hardware options like high-field-strength scanners and integrated high-density coil arrays, new sequences that combine parallel imaging, innovative k-space sampling and Dixon fat suppression with time-resolved imaging, new contrast agents with longer blood-pool residence time, and advanced post-processing solutions like image fusion. This article focuses on the principles of contrast-enhanced MR angiography of the body as it pertains to the physiologies and pathologies encountered in children. It also discusses tools to adapt the MR angiographic technique to the clinical indication, as well as pitfalls of post-processing and interpretation in commonly encountered vascular imaging scenarios in the pediatric body.

Optimal Diagnostic Yield Achieved With On-site Pathology Evaluation of Fine-Needle Aspiration–Assisted Core Biopsies for Pediatric Osseous Lesions: A Single-Center Experience

CONTEXT - Image-guided, fine-needle aspiration-assisted core needle biopsy with an on-site evaluation by a pathologist (FNACBP) of osseous lesions is not a common practice in pediatric institutions. OBJECTIVES - To evaluate the diagnostic adequacy and accuracy of FNACBP for pediatric osseous lesions and to compare the adequacy with procedures that do not use fine-needle aspiration. DESIGN - Six-year, retrospective review of 144 consecutive children biopsied for osseous lesions with and without fine-needle aspiration assistance. RESULTS - Pathologic diagnosis was achieved in 79% (57 of 72) of the core biopsies without an on-site evaluation, 78% (32 of 41) of the open biopsies (9 with intraoperative consultation), and 97% (30 of 31) of the FNACBPs as the initial diagnostic procedure. Three FNACBP cases were preceded by nondiagnostic open biopsies. Among 34 lesions sampled by FNACBP, 33 (97%) succeeded with diagnostic tissue, with most (30 of 33; 91%) being neoplasms, including 16 malignant (48%), 13 benign (39%), and 1 indeterminate (3%) lesions. The most-common diagnoses were osteosarcoma (9 of 33; 27%) and Langerhans cell histiocytosis (7 of 33; 21%). In cases with follow-up information available, 93% (28 of 30) of the FNACBP-rendered diagnoses were clinically useful, allowing initiation of appropriate therapy. The FNACBP procedure had 100% specificity, sensitivity, and positive predictive value for all 14 malignant lesions, with the sensitivity being 88% in benign lesions. Most FNACBP procedures (32 of 34; 94%) yielded adequate material for ancillary testing. A gradual upward trend was observed for the choice of FNACBP as an initial diagnostic procedure for osseous lesions. CONCLUSIONS - The FNACBP procedure yields sufficient material for diagnosis and ancillary studies in pediatric, osseous lesions and may be considered an initial-diagnostic procedure of choice.

Temporal Evolution and Management of Fast Flow Vascular Anomalies in PTEN Hamartoma Tumor Syndrome

Abstract Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is characterized by formation of recurrent benign tumors described as PTEN hamartoma of soft tissue that may contain fast flow vascular anomalies (FFVA). The purpose of this study is to review the temporal evolution and management of FFVA in PHTS. A retrospective review of 22 patients (9 males), age 1 to 18 (median 9) years diagnosed with PHTS at a tertiary care pediatric hospital between October 2002 and August 2017 revealed 4 patients with FFVA. Imaging, management, and treatment complications were reviewed. During median follow‐up of 8 (range: 4‐13) years, ultrasound and magnetic resonance imaging performed for recurrent pain, showed progressive increase in the size of hamartomas and development of new FFVA in three‐fourth patients. Medical management included pain medications, oral sirolimus, and physical and psychiatric therapy. Surgical excision of hamartoma (n = 1) resulted in recurrence within 3 months. Between 4 and 24 (average 1.5/year) embolizations were performed per patient. Pain related to FFVA responded well to embolization. Pain secondary to PTEN hamartoma responded poorly to percutaneous sclerosant injection, but demonstrated improvement with sirolimus. There was no correlation between serum sirolimus levels and frequency/timing of recurrence of FFVA/hamartoma. Complications included sclerosant migration into digital arteries (n = 1), subclavian vein stenosis due to glue migration (n = 1), oral mucositis (n = 4), and elevated triglycerides (n = 4). Patients with PHTS present with recurrent pain requiring life‐long management with a multi‐disciplinary team. Pain due to FFVA responds to embolization, and pain due to hamartoma responds to sirolimus. This improves quality of life, but does not prevent disease progression.

Dynamic contrast enhanced magnetic resonance lymphangiography: Categorization of imaging findings and correlation with patient management

OBJECTIVE To review the technical aspects and categorize the imaging findings of dynamic contrast enhanced magnetic resonance lymphangiography (DCMRL) and correlate the findings with patient management options. MATERIALS AND METHODS A retrospective review of patients who underwent DCMRL between June 2012 and August 2017 at a tertiary care paediatric hospital was performed. Twenty-five DCMRL studies were performed in 23 patients (9 males, 13 females, 1 ambiguous gender) with a median age of 4 years (range: 1 month-29 years). DCMRL imaging findings were reviewed, categorized and the impact on patient management was studied. RESULTS DCMRL was technically successful in 23/25 (92%) studies. DCMRL findings were categorized based on the status of central conducting lymphatics (CCL) and alternate lymphatic pathways as follows: Type 1 - normal CCL with no alternate lymphatic pathways, Type 2 - partial (2a) or complete (2b) non-visualization of CCL with reflux of contrast into alternate pathways and Type 3 - normal CCL with additional filling of alternate pathways. Type 1 DCMRL patients (n = 5) were reassured and conservative management was continued, Type 2 patients (n = 10) had evidence of CCL obstruction hence thoracic duct ligation or embolization was avoided and other options such as lymphatic fluid diversion using Denver® shunt or lympho-venous anastomosis were used, and Type 3 patients (n = 8) were evaluated for elevated central venous pressure as a cause of lymphatic backflow in addition to Denver® shunt, lympho-venous anastomosis, thoracic duct ligation or embolization. CONCLUSION DCMRL is an evolving imaging technique for understanding abnormalities of the central conducting lymphatics. Categorization of imaging findings may be helpful in guiding selection of management options.