[18F]mFBG Long Axial Field Of View (LAFOV) PET/CT without sedation or general anaesthesia compared to [123I]mIBG scintigraphy with single-photon emission computed tomography-CT (SPECT/CT) for imaging of children with neuroblastoma.

Introduction: Meta-[¹⁸F]fluorobenzylguanidine ([¹⁸F]mFBG) is a new positron emission tomography (PET) radiotracer that allows for fast and high-resolution imaging of tumours expressing the norepinephrine transporter. These initial results investigates the value of [¹⁸F]mFBG Long Axial Field Of View (LAFOV) PET/CT compared to 'standard' [¹²³I]mIBG scintigraphy with single-photon emission computed tomography-CT (SPECT/CT) for imaging in neuroblastoma.

Methods: Prospective, single-center study, that recruited children with neuroblastoma, referred for meta-[¹²³I]iodobenzylguanidine ([¹²³I]mIBG) whole body planar scintigraphy with SPECT/CT of the thorax and abdomen. Within 1 week of [¹²³I]mIBG scintigraphy, [¹⁸F]mFBG LAFOV PET/CT (Siemens Vision Quadra PET/CT) were performed at 1 h p.i. of [¹⁸F]mFBG (1.5-3 MBq/kg) without sedation or general anaesthesia (GA). The PET acquisition time was 10 min., if possible for the child, with only 2 min. of reconstruction required (being the minimum required scanning time in order to provide a clinically useful image) and by scanning 10 min. the periods without motion artefacts could be reconstructed. Tumour localisation and extension on paired scan were compared.

Results: 16 paired [¹²³I]mIBG and [¹⁸F]mFBG scans were performed in 8 patients (median age 3.25 years (0.25-8.08 y), n = 2 stage L2(low risk), n=1 stage L2(intermediate risk), n=1 stage L2(high risk/relaps), n=2 stage M (high risk), n=1 stage M (high risk/relaps), n=1 stage MS. Mean scan time for [¹⁸F]mFBG PET-CT (7.7 min, SD 2.6) was significantly shorter than for [¹²³I]mIBG scanning (72.5 min, SD 16.3), p < 0.01. None of the children had sedation or GA during the PET scanning procedure, whereas 81% had GA during the [¹²³I]mIBG scintigraphy with SPECT/CT. Compared to [¹²³I]mIBG scintigraphy, [¹⁸F]mFBG PET-CT detected a higher, equal, and lower number of avid lesions in 75%, 25%, and 0% of scan pairs, respectively. Especially, intraspinal-, retroperitoneal lymph node-, and bone marrow involvement is diagnosed with much higher accuracy in [¹⁸F]mFBG LAFOV PET/CT compared to [¹²³I]mIBG scintigraphy with SPECT/CT.

Conclusions: Preliminary results demonstrate that more neuroblastoma localisations were detected on [¹⁸F]mFBG LAFOV PET/CT compared to [¹²³I]mIBG scintigraphy with SPECT/CT. The clinical benefit of [¹⁸F]mFBG LAFOV PET/CT is a 1 day protocol, much shorter scan time and avoidance of GA/sedation in most patients. [¹⁸F]mFBG LAFOV PET/CT shows promise for future staging and response assessment in neuroblastoma in children.

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