Post surgical 123I-MIBG SPECT/CT in neuroblastoma

364 Objectives 123I-MIBG is the reference functional imaging tool in the characterization of primary tumor and the detection of distant metastases in neuroblastoma. In post surgical situation, 123I-MIBG is of importance to assess eventual residual viable tissue in the surgical site and is the reference functional exam for follow up. In this study, we performed and compared 123I-MIBG SPECT/CT to 123I-MIBG planar imaging and morphological imaging (MRI, CT, US) to assess eventual residual tissue after surgery for neuroblastoma. Methods 123I -MIBG SPECT/CT imaging was systematically performed in the post surgical period in addition to morphological exams in 16 patients operated for neuroblastoma (age=33.5 months, range 6 -78 months). 13 patients had early post surgical period 123I-MIBG exam (mean: 29 days ; range 8-42 days) ; 3 patients in the delayed post surgical period (mean 26 months) and 123I-MIBG was repeated in 1 patient 11 months after the first early post surgical MIBG exam. 123I-MIBG SPECT/CT was centered on the surgical site, mainly on the thoraco-abdominal area. SPECT/CT MIBG uptake in surgical site tissue was interpreted in correlation with morphological imaging data. Results Contrary to planar 123I-MIBG imaging, 123I-MIBG SPECT/CT allowed precisely assessing uptake in surgical site in all patients. 123I-MIBG SPECT/CT showed no MIBG uptake in surgical site in 12 patients. Among 8 of these patients, no MIBG uptake was found at the place of remnant tissue visualized in the surgical site on morphological imaging. Focal uptake was found in residual tissue in 4 patients ; the focal uptake was unchanged in the residual tissue for the repeated MIBG exam in 1 patient. Conclusions 123I-MIBG SPECT/CT is strongly recommended in addition to morphological imaging in post surgical period in neuroblastoma as a key tool to assess and follow eventual residual tissue in surgical site. Further studies are needed to assess prognostic implication and impact for patient’s management.