The significance of iodine 123 MIBG SPECT/CT for the diagnosis and treatment planning in neuroblastoma

Objectives 123I-MIBG (MIBG) SPECT/CT allows a direct correlation between functional and anatomical imaging and CT based attenuation correction improves the accuracy. The aim was to assess the significance of MIBG SPECT/CT imaging for the diagnosis and localization of neuroblastoma in comparison to planar and SPECT imaging.

Methods A total of 44 MIBG scans were performed for 18 patients (1 months - 15 y)with neuroblastoma.The MIBG images were obtained in the context of the initial staging,restaging and follow-up. MIBG SPECT/CT images were compared to planar and SPECT imaging alone regarding the delivery of diagnostic information and diagnostic reliability. Histology, follow up of the patients and conventional radiological imaging, especially MRI served as reference standard. For clarification of suspected MRI findings SPECT and MRI images were fused using CT anatomical landmarks.

Results Compared to planar and SPECT images, SPECT/CT could significantly provide additional diagnostic information. The sensitivity, specificity, PPV and NPV of MIBG SPECT/CT, SPECT and planar images were 98%, 100%, 100%, 97% ; 65%, 88%, 91% , 57.6% and 46.7%, 96.7%, 96%, 47.6% respectively. SPECT/CT completed the MRI findings especially with regard to tumor burden in 31% of studies. Suspected MRI findings could be confirmed as malignant after fusion of SPECT and MRI images in 56% of the scans. The therapy plan was changed according to the results of MIBG SPECT/CT in 6.3% of studies.

Conclusions MIBG SPECT/CT imaging has an important role to reduce false negative and false positive results compared to planar and SPECT imaging and is a sensitive and specific method in patients with neuroblastoma. Its particular strength lays in the detection of local recurrence and smaller tumor lesions. Moreover, it can provide additional information compared to MRI and allows a more accurate assessment of tumor burden. MIBG SPECT/CT can also affect the treatment planning