2415. Adequacy, Diagnostic Rate, and Safety of MR-Guided Core Needle Biopsies in Pediatric Patients
Authors * Denotes Presenting Author
  1. Guenther Schneider *; Saarland University Medical Center
  2. Caroline Grund; Saarland University Medical Center
  3. Arno Buecker; Saarland University Medical Center
The aim of our study was to assess adequacy, diagnostic rate and safety of MRI-guided core needle biopsies in pediatric patients with benign and malignant lesions. All biopsies were performed on closed-bore 1.5 or 3 T MRI systems and sedation of the patients for biopsy was carried out depending on the age of children. In most patients, biopsy was carried out during routine diagnostic imaging for staging of disease, so complete work up of patients was performed in a single exam.

Materials and Methods:
This study retrospectively analyzed 93 MRI-targeted core-needle biopsies in 90 pediatric patients 4 months to 19 years, mean age: 8 years, m/f=50/40). Biopsies were conducted between 2014 and 2022. Biopsy sides included neck (3 biopsies), thorax (6), abdomen (17), retroperitoneum (15), pelvis (14), musculoskeletal (29) and other soft tissue areas such as subcutaneous fat (9). In 78 cases, MRI-targeted biopsy was initiated for initial diagnosis, and 15 biopsies were performed to assess suspected recurrent disease. A biopsy was considered adequate, if representative specimen were obtained for histopathological analysis. A biopsy was considered diagnostic if unequivocal characterization of the target lesion was possible and matched subsequent clinical management and outcome. Safety of MRI-guided biopsy was analyzed by means of reported procedure-bound complications and follow-up.

Percutaneous MRI-guided biopsy yielded an overall adequacy of 95%, and the overall diagnostic rate was 86%. In malignant lesions, biopsy was adequate in 38/39 (97%) and diagnostic in 36/39 (92%) of the cases. Malignant lesions included 10 Neuroblastoma, 1 Nephroblastoma, 1 Renal cell carcinoma, 8 Ewing’s Sarcoma, 1 Osteosarcoma, 6 Soft tissue sarcoma, 8 Lymphoma, 3 Hepatoblastoma and 1 Hepatic metastasis (choroidal melanoma). For benign lesions, biopsy was adequate in 50/54 (93%) and diagnostic in 45/54(83%) of cases. Biopsy was nondiagnostic in 12 cases, entailing four diagnostic surgeries and two repeated biopsies. Reasons for nondiagnostic biopsies were necrotic tissue, vascular tumors without sufficient solid tissue areas for diagnosis as well as heterogeneous tumors without clear differentiation and biopsy of a LN without tumor involvement. Four (4%) procedure-bound complications were reported, all of them uncomplicated local hemorrhages that did not require further treatment. With regard to the target size in lesions = 1 cm (n = 13) 12 of 13 (92%) specimen were adaequate, in lesions 1 - 3 cm (n = 47) 43 (91%), 3 - 5 cm (n = 15) 15 (100%) and >5 cm (n = 18) 18 (100%).

Percutaneous MRI-guided core needle biopsy in pediatric patients provides adequate and accurate tissue sampling for various malignant and benign lesions with a low incidence of procedure-bound complications and complements or may even replace CT- or US-guided procedures. MRI-guided biopsy in pediatric patients is a safe and accurate technique which allows for biopsies of very small lesions due to the very good tissue contrast and a low rate of nondiagnostic tissue samples.