131I-MIBG in the diagnosis of primary and metastatic neuroblastoma

Neuroblastoma is the third most common malignancy of childhood. 131I-MIBG scintigraphy must be performed in patients with neuroblastoma at the time of staging. The aim of this study is to identify the role of 131I-MIBG scintigraphy in neuroblastoma patients in correlation with other diagnostic modalities for staging of the disease.

Twenty six patients provisionally diagnosed by clinical and imaging criteria to have neuroblastoma were included. On histopathologic verification 5 of these 26 patients were rediagnosed as non-neuroblastoma. Each patient had imaging by ultrasound, CT and/or MRI. In all cases, 131I-MIBG scintigraphy was performed, among them 15 patients had additional 99mTc-MDP bone scan.

The outcome demonstrated that CT and MRI were able to detect lesions in 19 out of 21 patients; while in 2 patients no lesions were detected. 131I-MIBG showed active lesions in 16 out of the above 19 patients, while in 3 patients 131I-MIBG was negative. There were no false positive result by 131I-MBG scan. Accordingly, 131I-MIBG is able to detect neuroblastora lesions with an overall sensitivity of 84.2%, specificity of 100% and an accuracy of 85.7%. Detection of primary lesions by 131I-MIB was significantly better than 99mTc-MDP bone scanning (92.31% vs. 61.54% respectively) (P < 0.05). For skeletal metastases, 131I-MIBG scan has a higher ability to detect more lesions than 99mTc-MDP bone scan (P = 0.023).

131I-MIBG scintigraphy has an excellent ability to discriminate between neuroblastonia and other small round cell paediatric tumours. 131I-MIBG was found to be significantly superior to conventional bone scanning in revealing both primary and metastatic osseous lesions.