131i-mibg in neuroblastoma, is not simply the uptake in the primary mass

Abstract EN

Neuroblastoma is the third most common malignancy of childhood.

Nowadays, MIBG has become a central procedure for staging and defining extent and location of neuroblastoma tumors.

The recommendations of the International Neuroblastoma Staging System (INSS) indicate that MIBG scintigraphy must be performed in patients with neuroblastoma at the time of initial staging and as a follow-up tool during therapy.

Purpose: Of this study is to identify the role of 131I-MIBG scintigraphy in neuroblastoma patients and to correlate it with other diagnostic modalities for staging and follow up of neuroblastoma.

Methods : the study was conducted on 26 patients provisionally diagnosed to have neuroblastoma.

On his to-pathologic verification 5 of these 26 patients were rediag-nosed as non-neuroblastoma.

Since the study aims at assessing the diagnostic power of 131I-MIBG scan, these 5 cases were not excluded.

The 21 histopathologically diagnosed as neuroblastoma were 11 patients in stage I V, 7 in stage III and 1 patient in each of stages I, II and IV-S.

Each, patient underwent a standard comprehensive diagnostic work up, Radiological imaging by conventional X-ray, ultrasound, CT and/or MRI was carried out.

In all patients 131I-MIBG scintigraphy was performed, among them 15 patients underwent additional 99mTc-MDP bone scan as well.

Results: The 21 neuroblastoma patients were studied according to the results obtained from CT, MRI and 131I-MIBG scanning.

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 scan showed actively functioning lesions in 16 out of the above 19 patients, while in 3 patients MIBG scan was negative.

There was no false positive result by 131I-MIBG scan.

Accordingly, 131I-MIBG is able to detect neuroblas-toma lesions with an overall sensitivity of 84.2 %, specificity of 100 % and an accuracy of 85.7 %.

Detection of primary lesions by 131I-MIBG was significantly better than 99mTc -MDP bone scanning (92.31 % vs 61.54 % respectively) (p < 0.01).

For skeletal metastases, 131I-MIBG scan has a higher ability to detect more lesions than 99mTc-MDP bone scan (p = 0.023).

Conclusions : 131I-MIBG has excellent ability to discriminate between neuroblastoma and other small round cell pediatric tumors.

131I-MIBG was found to be significantly superior to conventional bone scanning in revealing both primary and metastatic osseous lesions.

It is recommended to perform 131I-MIBG scanning at initial presentation to confirm the histopathology diagnosis and to monitor subsequent response to therapy.