Inclusion Criteria:

• - Subject is aged 18 years or older - Signed Informed Consent - Subject is diagnosed with a neural crest tumor or neuroendocrine tumor - Subject is judged to be in good general condition by the investigator on the basis of medical history, physical examination including vital signs and clinical laboratory tests, besides the diagnosis of a neural crest tumor - Subject should have a routine clinical 123I-MIBG scintigraphy (planar + SPECT/CT) performed within 6 months prior to the inclusion visit or scheduled within 3 months after the inclusion visit - Female subjects should be post-menopausal or surgically sterile or using effective contraceptive with negative pregnancy test

  Exclusion Criteria:

  - Subject has a previous or ongoing recurrent or chronic disease, other than a neural crest tumor, at high risk to interfere with the evaluation of the trial according to the judgement of the investigator, e.g. known gastro-intestinal, hepatic, renal, cardiovascular, metabolic or hormonal disease, cancer, major neurological or convulsive disorder or any psychiatric disease - Subject is currently, or within two weeks prior to the inclusion visit, a user (including ''recreational use'') of any illicit drugs, including cannabis, or has a history of drug or alcohol abuse - Subject is unable to refrain from smoking more than 10 cigarettes per day during the study - Subject has had exposure to ionizing radiation (> 1 mSv) in other research studies within the last 12 months - Subject suffers from claustrophobia or cannot tolerate confinement during PET/CT scanning procedures; subject cannot lie still for 60 minutes inside the scanner - Subject is unwilling to avoid unusual, unaccustomed, or strenuous physical activity (i.e. weight lifting, running, bicycling) from the time of the selection visit until the final safety telephone follow-up interview - Subject does not understand the study procedure - Subject is unwilling or unable to perform all of the study procedures, or is considered unsuitable in any way by the principal investigator.

- Subject is potentially pregnant (serum and urinary hCG test will be performed in women where pregnancy is not excluded) or is breast-feeding - Subject has recently (< 30 days or 5 times the plasma half-life of the investigated drug, whichever is longest) participated or is simultaneously participating in another prospective interventional clinical trial - Subject has a history of multiple and/or severe allergies to drugs or food - Subject underwent surgery between the selection and inclusion visit - Subject is mentally or legally incapacitated

Ten neural crest tumor or neuroendocrine tumor (NET) patients, with a routine clinical 123I-metaiodobenzylguanidine (123I-MIBG imaging) (planar + single photon emission tomography (SPECT)) performed in the previous six months or scheduled within three months, will undergo a dynamic PET scan for the first 30 minutes, followed by 3 static whole-body PET/CTs up to three hours post injection for a pharmacokinetics study and efficacy assessment of 18F-MFBG in humans. Furthermore, a comparison with 123I-MIBG imaging will be performed.

Arms

Experimental: Patients

A single dose of 18F-MFBG will be intravenously injected in 10 patients with neural crest tumors or neuroendocrine tumors. Patients will first undergo a dynamic PET scan, followed by whole-body PET/CT scans at various time points for a pharmacokinetics study and efficacy assessment.

Interventions

Drug: - (18F)MFBG

One intravenous injection of 4 MBq/kg

Device: - PET/CT

Patients will undergo a dynamic PET scan for the first 30 minutes, followed by 3 static whole-body PET/CTs at 60 ± 10 min, 120 ± 30 min and 180 ± 30 min post injection.

Other: - Venous blood samples

Blood samples will be obtained for laboratory safety evaluation for initial screening and safety evaluation after injection. Furthermore, venous blood samples will be obtained for metabolite analysis and activity measurements at various time points post injection (5 ± 2 min, 10 ± 5 min, 20 ± 10 min, 40 ± 20 min, 60 ± 30 min, 120 ± 60 min).