ABSTRACT. Magnetic resonance (MR) imaging (MRI)has the advantage of demonstrating lesions not visualized by other radiologic modalities. We present a case involving pediatric malignancy where MR-guided bone biopsy confirmed correct histologic diagnosis and was used to plan additional treatment. A 2-year, 9-month-old boy had a history of spontaneous regression of stage 4S neuroblastoma. 123 I-metaiodobenzylguanidine scintigraphy showed a hot spot at his right lower leg; however, neither plain radiograph 99m Tc diphosphonate bone scan was positive. Only MRI depicted a lesion at the distal third of his right tibia, and a subsequent MR-guided bone biopsy was diagnostic of bone marrow metastasis. After 6 courses of intensive chemotherapy, he has been in complete remission. MR-guided biopsy technique is likely to be particularly useful for the resection of invisible metastatic lesions, especially those that are only visible using MRI. Pediatrics 2002;109(1). URL: http:// www.pediatrics.org/cgi/content/full/109/1/e18; magnetic resonance imaging, biopsy, neoplasm.ABBREVIATIONS. MR, magnetic resonance; MRI, magnetic resonance imaging; VMA, vanillylmandelic acid; HVA, homovanillic acid; MIBG, metaiodobenzylguanidine. M agnetic resonance (MR) imaging (MRI) has the advantage of demonstrating lesions not visualized on computed tomography or other conventional imaging methods. 1 Moreover, it is extremely sensitive in detecting abnormalities of bone marrow. 2 When an abnormality can be seen on MRI only, or can be seen significantly better on MR images, MR-guided interventional surgery may be required for diagnosis and therapy. In this report, we present a case of pediatric malignancy where bone biopsy under real-time MR guidance was diagnostic of metastasis.
CASE REPORTA 2-year, 9-month-old boy had a history of spontaneous regression of stage 4S neuroblastoma. He was found to have bilateral adrenal tumors and multiple liver masses on the abdominal ultrasound at his regular 1-month-old infant health checkup. Blood neuron specific enolase was high (72 ng/mL), and urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) were elevated, 435 mg/g creatinine, 153 mg/g creatinine, respectively. Bone marrow aspiration did not show pathology. The diagnosis of stage 4S neuroblastoma was confirmed by a biopsy of skin metastasis. N-myc was not amplified, with a weak Trk-A expression. There was no 1p deletion. With all these favorable biological features except for a diploid DNA content, a wait-and-see strategy was initiated. By the age of 1 year 4 months, spontaneous regression of all the tumor was detected by graphic studies including ultrasound, computed tomography scan, MRI, and 123 I-MIBG (metaiodobenzylguanidine) scan. Although decreasing, urinary VMA and HVA excretions remained in higher levels, 26 mg/g creatinine and 56 mg/g creatinine, respectively. Now, at the age of 2 years and 9 months, a repeat MIBG scan showed a hot spot at his lower extremity (Fig 1). Neither plain radiographs nor 99m Tc diphosphate bone scan showed an...