Bone and lymph node metastases from neuroblastoma detected by 18F-DOPA-PET/CT and confirmed by posttherapy 131I-MIBG but negative on diagnostic 123I-MIBG scan

The evidence-based role of catecholaminergic PET tracers in Neuroblastoma. A systematic review and a head-to-head comparison with mIBG scintigraphy

BACKGROUND

Molecular imaging is pivotal in staging and response assessment of children with neuroblastoma (NB). [123I]-metaiodobenzylguanidine (mIBG) is the standard imaging method; however, it is characterised by low spatial resolution, time-consuming acquisition procedures and difficult interpretation. Many PET catecholaminergic radiotracers have been proposed as a replacement for [123I]-mIBG, however they have not yet made it into clinical practice. We aimed to review the available literature comparing head-to-head [123I]-mIBG with the most common PET catecholaminergic radiopharmaceuticals.

METHODS

We searched the PubMed database for studies performing a head-to-head comparison between [123I]-mIBG and PET radiopharmaceuticals including meta-hydroxyephedrine ([11C]C-HED), 18F-18F-3,4-dihydroxyphenylalanine ([18F]DOPA) [124I]mIBG and Meta-[18F]fluorobenzylguanidine ([18F]mFBG). Review articles, preclinical studies, small case series (< 5 subjects), case reports, and articles not in English were excluded. From each study, the following characteristics were extracted: bibliographic information, technical parameters, and the sensitivity of the procedure according to a patient-based analysis (PBA) and a lesion-based analysis (LBA).

RESULTS

Ten studies were selected: two regarding [11C]C-HED, four [18F]DOPA, one [124I]mIBG, and three [18F]mFBG. These studies included 181 patients (range 5-46). For the PBA, the superiority of the PET method was reported in two out of ten studies (both using [18F]DOPA). For LBA, PET detected significantly more lesions than scintigraphy in seven out of ten studies.

CONCLUSIONS

PET/CT using catecholaminergic tracers shows superior diagnostic performance than mIBG scintigraphy. However, it is still unknown if such superiority can influence clinical decision-making. Nonetheless, the PET examination appears promising for clinical practice as it offers faster image acquisition, less need for sedation, and a single-day examination.

Clinical utility of nuclear imaging in the evaluation of pediatric adrenal neoplasms

Adrenal neoplasms rarely occur in children. They can be diagnosed in the presence of endocrine, metabolic or neurological problems, an abdominal mass, more rarely an adrenal incidentaloma, or in the context of an adrenal mass discovered in the evaluation of childhood cancer including hematologic malignancy. According to standard medical practice, pediatric malignancies are almost always evaluated by ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography ([¹⁸F]FDG PET/CT). Nuclear imaging using specific radiotracers is also an important tool for diagnosing and staging neuroblastoma, pheochromocytoma, hormone hypersecretion, or indeterminate adrenal masses. The Hippocratic oath "primum non nocere" encourages limitation of radiation in children per the ALARA concept (as low as reasonably achievable) but should not lead to the under-use of nuclear imaging because of the potential risk of inaccurate diagnosis or underestimation of the extent of disease. As in adults, nuclear imaging in children should be performed in conjunction with hormone evaluation and morphological imaging.

Diagnostic Value of Seven Different Imaging Modalities for Patients with Neuroblastic Tumors: A Network Meta-Analysis

Objective

We performed a systematic review and network meta-analysis (NMA) to compare the diagnostic value of seven different imaging modalities for the detection of neuroblastic tumors in diverse clinical settings.

Methods

PubMed, Embase, Medline, and the Cochrane Library were searched to identify eligible studies from inception to Sep 29, 2020. Quality assessment of included studies was appraised with Quality Assessment of Diagnostic Accuracy Studies. Firstly, direct pairwise meta-analysis was conducted to calculate the pooled estimates of odds ratio (OR) and 95% confidence interval (CI) of the sensitivity, specificity, NPV, PPV, and DR. Next, NMA using Bayesian methods was performed. The superiority index was assessed to quantify the rank probability of a diagnostic test. The studies performed SPECT/CT or SPECT were analyzed separately from the ones only performed planar imaging.

Results

A total of 1135 patients from 32 studies, including 7 different imaging modalities, were eligible for this NMA. In the pairwise meta-analysis, ¹⁸F-FDOPA PET/CT had a relatively high value of all the outcomes (sensitivity: 10.195 [5.332–19.493]; specificity: 17.906 [5.950–53.884]; NPV: 16.819 [7.033–40.218]; PPV: 11.154 [4.216–29.512]; and DR 5.616 [3.609–8.739]). In the NMA, ¹⁸F-FDOPA PET/CT exhibited relatively high sensitivity in all subgroups (all data: 0.94 [0.87–0.98]; primary tumor: 0.89 [0.53–1]; bone/bone marrow metastases: 0.96 [0.83–1]; and primary tumor and metastases (P + M): 0.92 [0.80–0.97]), the highest specificity in the subgroup of P + M (0.85 [0.61–0.97]), and achieved the highest superiority index in the subgroups of all data (8.57 [1–15]) and P + M (7.25 [1–13]).

Conclusion

¹⁸F-FDOPA PET/CT exhibited the best diagnostic performance in the comprehensive detection of primary tumor and metastases for neuroblastic tumors, followed by ⁶⁸Ga-somatostatin analogs, ¹²³I-meta-iodobenzylguanidine (MIBG), ¹⁸F-FDG, and ¹³¹I-MIBG tomographic imaging.

Metastatic Neuroblastoma to the Mandible of Children: Report of Two Cases and Critical Review of the Literature

Neuroblastoma is the most common extracranial solid cancer of infancy, occurring mainly in the adrenal gland, with high metastatic potential. However, involvement of the head and neck region is rare. Here, we present two cases of metastatic neuroblastoma of childhood, in which a mandibular swelling was the first sign of disseminated disease. Case 1 describes a 4-year-old boy with a 2-week history of painful swelling in the left mandibular region, body soreness and weakness. Panoramic radiography and computed tomography showed a destructive lesion in the left mandibular ramus. Case 2 describes a 3-year-old boy with a 1-month history of swelling in the right mandibular area. Panoramic radiograph and cone-beam computed tomography showed a destructive lesion in the right body and ramus of the mandible, displacing tooth germs, with the destruction of vestibular and lingual bone cortices. In both cases, microscopic analyses revealed a diffuse proliferation of small, round, and blue cells with hyperchromatic nuclei and scant cytoplasm. While Case 1 was more undifferentiated, Case 2 presented eosinophilic areas suggestive of neuropil. A large immunohistochemical panel was performed, showing expression of neural markers such as CD56, neuron-specific enolase (in Case 2), chromogranin, and synaptophysin. Both lesions presented a high proliferation index (Ki67 > 70% and 80%, respectively). Positron emission tomography-computed tomography revealed ipsilateral adrenal primary lesions in both cases, with multiple bone metastatic lesions. Besides the mandible, multiple sites of the axial and appendicular skeleton were affected. Treatment consisted of induction chemotherapy, adrenalectomy, consolidation chemoradiotherapy, and post-consolidation therapy.

Roles of PET/Computed Tomography in the Evaluation of Neuroblastoma

Neuroblastoma is one of the most common pediatric malignant tumors. Functional imaging plays an important role in the diagnosis, staging, and therapy response monitoring of neuroblastoma. Although metaiodobenzylguanidine scan with single-photon emission computed tomography/computed tomography remains the mainstay in functional imaging of the neuroblastomas, PET/CT has begun to show increased utility in this clinical setting.

Three-step two-pot automated production of NCA [18F]FDOPA with FlexLab module

Automated three-step two-pot production of no-carrier-added (NCA) [¹⁸F]FDOPA was first implemented in the iPHASE FlexLab module. Decay-corrected radiochemical yield (RCY) of [¹⁸F]FDOPA synthesized by this method was 10~14% (n = 7) with a synthesis time of ~110 min [¹⁸F]FDOPA was obtained in > 95% of radiochemical purity with a molar activity of ~431 GBq/μmol. With the method successfully implementing on the commercial FlexLab module and its built-in step-by-step activity monitoring, further processes optimization would be achieved.

Guidelines on nuclear medicine imaging in neuroblastoma

Nuclear medicine has a central role in the diagnosis, staging, response assessment and long-term follow-up of neuroblastoma, the most common solid extracranial tumour in children. These EANM guidelines include updated information on ¹²³I-mIBG, the most common study in nuclear medicine for the evaluation of neuroblastoma, and on PET/CT imaging with ¹⁸F-FDG, ¹⁸F-DOPA and ⁶⁸Ga-DOTA peptides. These PET/CT studies are increasingly employed in clinical practice. Indications, advantages and limitations are presented along with recommendations on study protocols, interpretation of findings and reporting results.