Hybrid Single Photon Emission Tomography/Computed Tomography (SPET/CT ) imaging is becoming the standard of care in pediatric imaging and one of the main indication is for metaiodobenzylguanidine (MIBG) scintigraphy in Neuroblastoma (NBL). Reviewing our experience, we discuss the feasibility and the clinical added value of manual fusion for correlation of 123I MIBG scintigraphy and diagnostic CT in pediatric NBL management.
We retrospectively evaluated 675 123I-MIBG scintigraphies (planar and SPET images) of 238 children (133 males and 105 females, age range at presentation 1 month – 15 years) which referred to our Institution for NBL from 2003 to 2014. Planar imaging was performed by a single head gamma-camera (Ecam, Siemens) acquiring spot images of the entire body according to the EANM guidelines. High quality SPET images were performed using a well-defined acquisition protocol (64 views, zoom factor: 1, acquisition matrix: 128×128, frame duration: 35 sec). All planar and SPET images were acquired during natural sleep or getting children cooperation. Since 2009, all SPET studies (93 SPET examinations, 70 of whom in the last 2 years , in 57 patients) were processed by manual fusion with diagnostic CT by a dedicated software (Siemens ESOFT Workstation), previously validated by a wide range of phantom studies.
In 16/93 (17%) patients SPET/CT fused images confirmed the absence of 123I-MIBG uptake showed by planar images; in 57/93 (61%) patients SPET/CT fused images provided additional information about extension, number and site of uptake foci revealed by planar acquisition (skull in 10 patients, spine in 4, lymph-nodes in 4, chest wall in 2 and residual disease in the abdomen in 37) ; in 20/93 (22%) SPET/CT fused images confirmed planar images findings.
In our experience, also in absence of an hybrid tomograph, SPET/CT image fusion is feasible. Our results confirm combined anatomical-functional imaging with SPET/CT has a higher diagnostic accuracy than planar imaging and this multimodality approach is crucial for defining risk stratification, disease assessment and the adequate treatment option in pediatric NBL management.