Similar Findings on 18F-MFBG PET/CT and 68Ga-DOTATATE PET/CT in a Patient With Widespread Metastatic Pheochromocytoma

18 F-MFBG PET/CT and MRI in Identifying Brain Metastases in a Posttreatment Neuroblastoma Patient

ABSTRACT

A 7-year-old girl with known brain metastasis from neuroblastoma developed new onset of severe headache. A brain MRI confirmed known metastasis in the right frontal lobe of the brain without new abnormalities. The patient was enrolled in a clinical trial using 18 F-MFBG PET/CT to evaluate patients with neuroblastoma. The images confirmed abnormal activity in the known lesion in the right frontal lobe. In addition, the PET showed additional foci of abnormal activity in the left cerebellopontine region. A follow-up brain MRI study acquired 4 months later revealed abnormal signals in the same region.

Gastroesophageal Reflux Revealed by 18 F-MFBG PET/CT

ABSTRACT

A 56-year-old woman who had a lung transplant 4 months ago presented frequent vomiting for 1 month. Barium meal and 99m Tc gastroesophageal scintigraphy showed no gastroesophageal reflux. The patient was enrolled in a clinical trial and underwent 18 F-MFBG PET/CT dynamic imaging. At the seventh minute of dynamic imaging, the images revealed reflux from the cardia into the esophagus and reached the oral cavity.

[18F]MFBG PET/CT outperforming [123I]MIBG SPECT/CT in the evaluation of neuroblastoma

PURPOSE

Iodine 123 labeled meta-iodobenzylguanidine ([123I]MIBG) scan with SPECT/CT imaging is one of the most commonly used imaging modalities in the evaluation of neuroblastoma. [18F]-meta-fluorobenzylguanidine ([18F]MFBG) is a novel positron emission tomography (PET) tracer which was reported to have a similar biodistribution to [123I]MIBG. However, the experience of using [18F]MFBG PET/CT in the evaluation of patients with neuroblastoma is limited. This preliminary investigation aims to assess the efficacy of [18F]MFBG PET/CT in the evaluation of neuroblastomas in comparison to [123I]MIBG scans with SPECT/CT.

MATERIALS AND METHODS

In this prospective, single-center study, 40 participants (mean age 6.0 ± 3.7 years) with history of neuroblastoma were enrolled. All children underwent both [123I]MIBG SPECT/CT and [18F]MFBG PET/CT studies. The number of lesions and the Curie scores revealed by each imaging method were recorded.

RESULTS

Six patients had negative findings on both [123I]MIBG and [18F]MFBG studies. Four of the 34 patients (11.8%) were negative on [123I]MIBG but positive on [18F]MFBG, while 30 patients were positive on both [123I]MIBG and [18F]MFBG studies. In these 34 patients, [18F]MFBG PET/CT identified 784 lesions while [123I]MIBG SPECT/CT detected 532 lesions (p < 0.001). The Curie scores obtained from [18F]MFBG PET/CT (11.32 ± 8.18, range 1-27) were statistically higher (p < 0.001) than those from [123I]MIBG SPECT/CT (7.74 ± 7.52, range 0-26). 30 of 34 patients (88.2%) with active disease on imaging had higher Curie scores based on the [18F]MFBG study than on the [123I]MIBG imaging.

CONCLUSION

[18F]MFBG PET/CT shows higher lesion detection rate than [123I]MIBG SPECT/CT in the evaluation of pediatric patients with neuroblastoma.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov : NCT05069220 (Registered: 25 September 2021, retrospectively registered); Institute Review Board of Peking Union Medical College Hospital: ZS-2514.

Comparison of 18 F-FDOPA and 18 F-MFBG PET/CT Images of Metastatic Pheochromocytoma

ABSTRACT

A 30-year-old man with pheochromocytoma was hospitalized for hemoptysis without inducement. CT revealed a mass in the left lung, and biopsy pathology under the bronchoscope suggested that it was a pheochromocytoma metastasis. To further identify the location of the metastatic lesions, the patient was enrolled in a clinical trial and underwent 18 F-FDOPA and 18 F-MFBG PET/CT. Images from both examinations showed similar lesions. However, the lesions differed in that the uptake of some lesions was significantly higher with 18 F-FDOPA than with 18 F-MFBG, whereas the para-aortic lesion was active in 18 F-MFBG but not in 18 F-FDOPA.

Recent Advances in Radiopharmaceutical Theranostics of Pheochromocytoma and Paraganglioma

As a rare kind of non-epithelial neuroendocrine neoplasms, paragangliomas (PGLs) exhibit various clinical characteristics with excessive catecholamine secretion and have been a research focus in recent years. Although several modalities are available nowadays, radiopharmaceuticals play an integral role in the management of PGLs. Theranostics utilises radiopharmaceuticals for diagnostic and therapeutic intentions by aiming at a specific target in tumour and has been considered a possible means in diagnosis, staging, monitoring and treatment planning. Numerous radiopharmaceuticals have been developed over the past decades. 123/131-Metaiodobenzylguanidine (123/131I-MIBG), the theranostics pair target on norepinephrine transporter system, has remained a fantastic protocol for patients with PGLs because of disease control with limited toxicity. The high-specific-activity 131I-MIBG was authorised by the Food and Drug Administration as a systemic treatment method for metastatic PGLs in 2018. Afterward, peptide receptor radionuclide therapy, which uses radiolabelled somatostatin (SST) analogues, has been exploited as a superior substitute. 68Ga-somatostatin analogue (SSA) PET showed significant performance in diagnosing PGLs than MIBG scintigraphy, especially in patients with head and neck PGLs or SDHx mutation. 90Y/177Lu-DOTA-SSA is highly successful and has preserved favourable safety with mounting evidence regarding objective response, disease stabilisation, symptomatic and hormonal management and quality of life preservation. Besides the ordinary beta emitters, alpha-emitters such as 211At-MABG and 225Ac-DOTATATE have been investigated intensively in recent years. However, many studies are still in the pre-clinical stage, and more research is necessary. This review summarises the developments and recent advances in radiopharmaceutical theranostics of PGLs.

Molecular imaging Theranostics of Neuroendocrine Tumors

Neuroendocrine neoplasms (NEN) are rare and heterogeneous tumors, originating mostly from the gastro-entero-pancreatic (GEP) tract followed by the lungs. Multidisciplinary discussion is mandatory for optimal diagnostic and therapeutic management. Well-differentiated NEN (NET) present a high expression of somatostatin receptors (SSTR) and can be studied with [68Ga]-DOTA-peptides ([68Ga]Ga-DOTANOC, [68Ga]Ga-DOTATOC, [68Ga]Ga-DOTATATE) PET/CT to assess disease extension and the eligibility for peptide receptor radionuclide therapy (PRRT). SSTR-analogues labelled with 90Y or 177Lu have been used since mid-90s for NET therapy. PRRT is now considered an effective and safe treatment option for SSTR-expressing NET: following the approval of 177Lu-DOTATATE by FDA and EMA, PRRT is now part of the therapeutic algorithms of the main scientific societies. New strategies to improve PRRT efficacy and to reduce its toxicity are under evaluation (eg, personalization of treatment schemes, the selection of the most suitable patients, improvement of response assessment criteria, optimization of treatment sequencing, feasibility of PRRT-retreatment, combination of PRRT with other treatments options). Recently, several emerging radiopharmaceuticals showed encouraging results for both imaging and therapy (eg, SSTR-analogues labelled with 18F, SSTR-antagonists for both diagnosis and therapy, alpha-labelling for therapy, radiopharmaceuticals binding to new cellular targets). Aim of this review is to focus on current knowledge and to outline emerging perspectives for NEN's diagnosis and therapy.

18 F-MFBG PET/CT Is an Effective Alternative of 68 Ga-DOTATATE PET/CT in the Evaluation of Metastatic Pheochromocytoma and Paraganglioma

PURPOSE

The current guidelines state that the functional imaging choice in the evaluation of metastatic pheochromocytoma and paraganglioma (PPGL) is 68 Ga-DOTATATE PET/CT. 18 F-meta-fluorobenzylguanidine ( 18 F-MFBG) is a new PET tracer and an analog of meta-iodobenzylguanidine (MIBG). This study aimed to compare 18 F-MFBG and 68 Ga-DOTATATE PET/CT in patients with metastatic PPGL.

PATIENTS AND METHODS

Twenty-eight patients with known metastatic PPGL were prospectively recruited for this study. All patients underwent both 18 F-MFBG and 68 Ga-DOTATATE PET/CT studies within 1 week. Lesion numbers detected were compared between these 2 studies.

RESULTS

18 F-MFBG PET/CT was positive for detecting metastases in all patients, whereas positive results of 68 Ga-DOTATATE PET/CT were in 27 (96.4%) patients. A total of 686 foci of metastatic lesions were detected by both 18 F-MFBG and 68 Ga-DOTATATE imaging. In addition, 33 foci of abnormal activity were only detected by 18 F-MFBG, whereas 16 foci were only shown on 68 Ga-DOTATATE PET/CT.

CONCLUSIONS

Our data suggest that 18 F-MFBG PET/CT is an effective imaging method in the evaluation of metastatic PPGL and could be alternative of 68 Ga-DOTATATE PET/CT in this clinical setting.

[18F]mFBG PET-CT for detection and localisation of neuroblastoma: a prospective pilot study

PURPOSE

Meta-[¹⁸F]fluorobenzylguanidine ([¹⁸F]mFBG) is a positron emission tomography (PET) radiotracer that allows for fast and high-resolution imaging of tumours expressing the norepinephrine transporter. This pilot study investigates the feasibility of [¹⁸F]mFBG PET-CT for imaging in neuroblastoma.

METHODS

In a prospective, single-centre study, we recruited children with neuroblastoma, referred for meta-[¹²³I]iodobenzylguanidine ([¹²³I]mIBG) scanning, consisting of total body planar scintigraphy in combination with single-photon emission computed tomography-CT (SPECT-CT). Within two weeks of [¹²³I]mIBG scanning, total body PET-CTs were performed at 1 h and 2 h after injection of [¹⁸F]mFBG (2 MBq/kg). Detected tumour localisations on scan pairs were compared. Soft tissue disease was quantified by number of lesions and skeletal disease by SIOPEN score.

RESULTS

Twenty paired [¹²³I]mIBG and [¹⁸F]mFBG scans were performed in 14 patients (median age 4.9 years, n = 13 stage 4 disease and n = 1 stage 4S). [¹⁸F]mFBG injection was well tolerated and no related adverse events occurred in any of the patients. Mean scan time for [¹⁸F]mFBG PET-CT (9.0 min, SD 1.9) was significantly shorter than for [¹²³I]mIBG scanning (84.5 min, SD 10.5), p < 0.01. Most tumour localisations were detected on the 1 h versus 2 h post-injection [¹⁸F]mFBG PET-CT. Compared to [¹²³I]mIBG scanning, [¹⁸F]mFBG PET-CT detected a higher, equal, and lower number of soft tissue lesions in 40%, 55%, and 5% of scan pairs, respectively, and a higher, equal, and lower SIOPEN score in 55%, 30%, and 15% of scan pairs, respectively. On average, two more soft tissue lesions and a 6-point higher SIOPEN score were detected per patient on [¹⁸F]mFBG PET-CT compared to [¹²³I]mIBG scanning.

CONCLUSION

Results of this study demonstrate feasibility of [¹⁸F]mFBG PET-CT for neuroblastoma imaging. More neuroblastoma localisations were detected on [¹⁸F]mFBG PET-CT compared to [¹²³I]mIBG scanning. [¹⁸F]mFBG PET-CT shows promise for future staging and response assessment in neuroblastoma.

TRIAL REGISTRATION

Dutch Trial Register NL8152.

Comparison of 18 F-MFBG and 68 Ga-DOTATATE PET/CT in the Imaging of Metastatic Paraganglioma and Pheochromocytoma

ABSTRACT

Two men with metastatic paraganglioma/pheochromocytoma underwent PET/CT examination in our hospital to understand the treatment effect and progression of the disease. Both patients had previously been treated with 131 I-MIBG, and at this evaluation, both of them underwent 68 Ga-DOTATATE and 18 F-MFBG PET/CT. The 68 Ga-DOTATATE PET/CT showed more metastases in the images of these 2 patients. This case highlighted that 68 Ga-DOTATATE PET/CT is superior to 18 F-MFBG PET/CT in detecting metastases from paraganglioma and pheochromocytoma in these 2 patients.

MIBG Uptake in a Gastric Gastrointestinal Stromal Tumor

ABSTRACT

MIBG scintigraphy is the imaging choice in the evaluation of pheochromocytoma and neuroblastoma. 131 I-MIBG uptake by gastrointestinal stromal tumors was rare. Here we report a case in which an increased 131 I-MIBG activity in an endoluminal gastric gastrointestinal stromal tumor was noted.