n.94 – COMPARISON OF 18F-DOPA PET/CT AND 123 I-MIBG SPECT IN NEUROBLASTOMA PEDIATRIC PATIENT



Abstract

BACKGROUND-AIM
Neuroblastoma (NB) an embryogenic tumor of children derived from the peripheral sympathetic nervous system and produces catecholamines.
(18)F-Dopa positron emission tomography (PET)/CT has proved to be a valuable tool for the assessment of neuroendocrine tumors. So far no data are available on (18)F-dopa use in neuroblastoma (NB) in pediatric patient. Our aim was to evaluate the role of (18)F-dopa PET/CT in NB and compare its diagnostic performance with that of (123)I-metaiodobenzylguanidine (MIBG) scintigraphy in pediatric patients affected by stage 3-4 NB.
METHODS
We prospectively evaluated a total of 28 paired 123 I-MIBG and 18F-Dopa PET/CT scans in 19 consecutive patients with stage 3-4 NB. (15 M, 4F).
Four patient underwent our protocol at the time of the first NB diagnosis and 15 when disease relapse was suspected on routine clinical and conventional radiological imaging during follow-up.
No patient aged less then 1 year was included in our study. Paired scans were obtained in fasting patients within 10 days.
Image acquisition was performed according to standard procedures: 123I-MIBG scans were acquired 24h after injection of tracer.
Whole body 18F-Dopa PET/CT was carried out 60 min after the injection of tracer on an integrated PET/CT system (Discovery LS or STE, GE Medical System).
RESULTS
our final multidisciplinary diagnosis confirmed primary tumor/recurrence/metastasis of NB in 17of 19 patients. 18F-dopa PET/CT correctly identified NB localization in 16 (94%) of these patients, whereas 123I_MIBG scintigraphy did so in 11 patients (65%). Both disease-free patients who had been classified as positive on 123I-MIBG scintigraphy were correctly reevaluated as negative by 18F-DOPA PET/CT analysis. On scan-based analysis, 18F-dopa PET/CT showed a sensitivity and accuracy of 95% and 96% respectively, while I123-MIBG scanning showed sensitivity and accuracy 68% and 64% respectively p<0,05. No significant difference in terms of specificity was found between the two imaging modalities (P=0,2). The specificity of 18F-dopa PET/CT approached 100%.
The 18F-dopa PET/CT seemed to be slightly more sensitive, albeit without reaching statistical significance, than 123I-MIBG scintigraphy in detecting primary/residual tumor (66 vs 33%, p=0,07) but not in the case of bone marrow/bone recurrence (100 vs 90%).
We identified 156 NB localizations, 141 of which were correctly detected by 18F-dopa PET/CT and 88 by MIBG. In 9 of 28 paired scans (32%) PET/CT result influenced the patient management.
CONCLUSION
PET with 18F-dopa has the shortest execution time and is more suited to the pediatric patients.
The study showed that primary/residual, recurrent/metastatic soft tissue NB and bone/bone marrow NB metastases were all characterized by a specific 18F-dopa uptake. The pathological distribution of this PET tracer was similar to that of 123I-MIBG. 18F-dopa PET/CT displayed high overall diagnostic accuracy in stage 3-4 NB which was comparable to I123-MIBG scintigraphy results, providing outstanding information on disease extension.
The combination of morphological and functional imaging provided by PET / CT provided the best tool to guide the surgery that is the primary treatment of NB.
In addition to 18F-DOPA PET / CT does not require premedication and suspension of treatments; execution time is significantly shorter (1h vs 4-24h). Finally, F-DOPA PET/CT procedure delivers to the patient a lower exposure to ionizing radiation, characteristics that make it more suitable to the child.

Scarica PDF