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.

Significantly Elevated FDG Activity in Neurothekeoma.

ABSTRACT: Neurothekeoma is a very rare cutaneous lesion affecting mainly young patients. The lesion is generally benign. We report here that intense FDG activity on PET/CT was noted at the site of primary neurothekeoma of the right shoulder in a 16-year-old boy. Abnormal FDG activity was also seen in the metastatic neurothekeoma in the lung in the same patient 2 years later.

Recurrent Metastatic Ewing Sarcoma Involving Only in the Muscles of Extremities Shown on FDG PET/CT.

ABSTRACT: Ewing sarcoma is the second most common osseous malignancy in pediatric patient. Metastasis is common due to its aggressive nature, with 25% of patients with metastasis at diagnosis, commonly to the lungs, bone, or bone marrow. Muscle metastasis is uncommon. We report FDG PET/CT findings of multifocal muscle metastases of recurrent Ewing sarcoma in the extremities without lung and bone involvement in a 6-year-old boy.

Solitary Neuroblastoma in the Scapula.

ABSTRACT: Majority of primary pediatric neuroblastomas occur in the abdomen, followed by posterior mediastinum. A 7-year-old girl presented worsening pain in the left shoulder, and a CT image of the chest revealed osseous destruction in the left scapula, suggestive of bone tumor. A biopsy was performed. Pathological result was consistent with neuroblastoma. A 123I scan with SPECT/CT images was performed, which showed only increased activity in the left scapula without any other foci of abnormal activity elsewhere.

FDG PET/CT Findings of Renal Cell Carcinoma Arising From a Transplanted Kidney in a Pediatric Patient.

ABSTRACT: A 12-year-old girl presented with a history of kidney transplant complicated by posttransplant lymphoproliferative disease. A solid mass was found in the lower pole of the transplanted kidney, concerning for posttransplant lymphoproliferative disease. However, biopsy confirmed papillary renal cell carcinoma. FDG PET/CT showed increased activity in the known renal cell carcinoma in the renal allograft.

Outcomes of ATA Low-Risk Pediatric Thyroid Cancer Patients Not Treated With Radioactive Iodine Therapy.

CONTEXT: The American Thyroid Association (ATA) Pediatric Guidelines recommend patients not receive radioactive iodine therapy (RAIT) for differentiated thyroid cancer (DTC) confined to the thyroid. Since publication, there is ongoing concern whether withholding RAIT will result in a lower rate of remission. OBJECTIVE: This study explores whether ATA low-risk patients treated with and without RAIT achieved similar remission rates. METHODS: Medical records of patients <19 years old diagnosed with DTC and treated with total thyroidectomy between 2010 and 2020 were reviewed. Multivariate logistic regression was performed to evaluate factors influencing RAIT administration and remission rate. RESULTS: Ninety-five patients with ATA low-risk DTC were analyzed: 53% (50/95) and 47% (45/95) were treated with and without RAIT, respectively. RAIT was used to treat 82% of patients before 2015 compared with 33% of patients after 2015 (P < .01). No significant difference in 1-year remission rate was found between patients treated with and without RAIT, 70% (35/50) vs 69% (31/45), respectively. With longer surveillance, remission rates increased to 82% and 76% for patients treated with and without RAIT, respectively. Median follow-up was 5.8 years (IQR 4.3-7.9, range 0.9-10.9) and 3.6 years (IQR 2.7-6.6; range 0.9-9.3) for both cohorts. No risk factors for persistent or indeterminate disease status were found, including RAIT administration, N1a disease, and surgery after 2015. CONCLUSION: Withholding RAIT for pediatric patients with ATA low-risk DTC avoids exposure to radiation and does not have a negative impact on remission rates. Dynamic risk stratification at 1-year after initial treatment is a suitable time point to assess the impact of withholding RAIT for these patients.

[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.

Prolonged imaging time in the salivagram appears unnecessary for detecting aspiration.

Background: The salivagram was first described to detect possible lung aspiration in infants or young children. Its original protocol required dynamic imaging for 60 minutes, which has high sensitivity. The purpose of this retrospective investigation was to determine whether a shortened period of image acquisition can be adopted without significantly reducing the sensitivity of the test in detecting aspiration. Methods: The current salivagram protocol in our hospital requires 60 minutes of dynamic imaging. The images of a total of 398 patients (ages 1 month to 9 years old) with positive salivagrams were analyzed. The entire 60-minute dynamic images were divided into 6 periods, 10 minutes/period. The time of the onset of abnormal activity in the bronchi, which was evidence of aspiration in each patient, was recorded and assigned to the corresponding period. Results: Among all 398 patients with evidence of aspiration, tracheobronchial tree activity could be seen in the first 10 minutes of the dynamic imaging in 184 of them (46.2%, 184/398). The onset of the bronchial activity was seen between 10 and 20 minutes in 177 patients (44.5%, 177/398). A total of 35 patients (8.8%, 35/398) had the onset of abnormal tracheobronchial tree activity in the 3rd period between 20 and 30 minutes. During the 4th period between 30 and 40 minutes, the onset of the aspiration occurred in only 2 patients (0.5%, 2/398). All patients had the onset of aspiration in the first 40 minutes of the dynamic imaging. Conclusions: The originally described 60-minute dynamic imaging protocol of the salivagram can be safely shortened to 40 or even 30 minutes without a significantly decreased chance of detecting aspiration. Prolonged imaging is unnecessary.

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.

Excreted 99m Tc-Pertechnetate in a Renal Pelvis as a Potential False Positive in a Meckel's Scan.

ABSTRACT: A 14-year-old girl presented with right lower quadrant pain. A 99m Tc-pertechnetate scan with SPECT/CT was performed to exclude a Meckel's diverticulum. The images demonstrated focal tracer uptake in the right midabdomen, which appeared early and decreased over time. However, SPECT/CT revealed that this uptake corresponded to the right renal pelvis, which was located more inferior than expected. This case emphasizes the importance of recognizing anatomic variants that may cause focal tracer uptake, as well as leveraging an understanding of tracer kinetics to inform a diagnosis.

Cerebellar Metastasis From Thyroid Carcinoma With Prominent 123 I Uptake But Less Impressive MRI Findings in a Pediatric Patient.

ABSTRACT: Papillary thyroid carcinoma in childhood frequently presents with locoregional lymph node metastases. The distant metastases often involve lungs and the bone, whereas brain metastasis is rare. We report a case of classic variant-papillary thyroid carcinoma with right cerebellar metastasis in a 7-year-old girl on a 123 I SPECT/CT study. A brain MRI on the same day shows a tiny millimetric enhancing nodule in the right cerebellum with no perceivable perilesional edema, confirming the 123 I scan findings.

Ectopic Gallbladder in the Left Upper Abdomen Shown on Hepatobiliary Scintigraphy.

ABSTRACT: The gallbladder is normally located in the right upper abdomen below the undersurface of the liver. We reported an ectopically located gallbladder, which was located in the left upper abdomen on hepatobiliary scintigraphy in an 18-year-old woman.

Increased Genioglossus Muscle FDG Activity Due to Using Pacifier.

ABSTRACT: An 18-month-old girl with history of liver transplant underwent FDG PET/CT to evaluate posttransplant lymphoproliferative disorder. In addition to multistation hypermetabolic lymphadenopathy and abnormal activity in the liver, stomach, and small bowel, in keeping with known posttransplant lymphoproliferative disorder, the images also showed focal activity in the submental region. This submental activity persisted on 2 separate follow-up FDG PET/CT studies, even though other foci of abnormal activity resolved after chemotherapy. Records revealed that the patient was sucking on a pacifier prior to all 3 FDG PET/CT studies, and the submental uptake corresponded with genioglossus muscle activity.

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

ABSTRACT: A 27-year-old woman with known malignant pheochromocytoma was enrolled in a clinical trial to compare efficacy of 68Ga-DOTATATE PET/CT and 18F-MFBG PET/CT. Images from both studies detected similar number of the metastatic lesions. In addition, both studies detected more lesions than 131I-MIBG imaging.

An Atypical Case of Meckel's Diverticulum Assessed by SPECT/CT Imaging.

ABSTRACT: A 17-year-old adolescent boy presented with multiple episodes of hematochezia. After a negative 99mTcO4 scan, upper endoscopy, colonoscopy, and CT angiography, the patient underwent a second 99mTcO4 scan with ranitidine. The anterior images demonstrated a faint, delayed focus of uptake in the midabdomen without correlate on lateral projections. SPECT/CT was performed for localization with the focus of activity seen in an anterior loop of distal small bowel adjacent to the umbilicus. The patient subsequently underwent diagnostic laparoscopy and resection of the diverticulum with postoperative resolution of the symptoms.

18F-6-Fluoro-l-Dopa PET/CT Imaging of Congenital Hyperinsulinism.

Congenital hyperinsulinism is characterized by persistent hypoglycemia due to inappropriate excess secretion of insulin resulting in hyperinsulinemic hypoglycemia. The clinical course varies from mild to severe, with a significant risk for brain damage. Imaging plays a valuable role in the care of infants and children with severe hypoglycemia unresponsive to medical therapy. 18F-6-fluoro-l-dopa PET/CT is the method of choice for the detection and localization of a focal lesion of hyperinsulinism. Surgical resection of a focal lesion can lead to a cure with limited pancreatectomy. This article reviews the role of 18F-6-fluoro-l-dopa PET/CT in the management of this vulnerable population.

Hyperthyroidism Incidentally Noted on Lymphoscintigraphy.

ABSTRACT: A 43-year-old woman with edema in both left upper limb and lower limb underwent lymphoscintigraphy to evaluate possible lymphedema. Two separate lymphoscintigraphies, one for the lower and the other for the upper limbs, were performed with interval of 3 days. Incidentally, an activity in the region of the thyroid glands was noted in the delayed images of both studies. Subsequently, Graves disease was diagnosed based on the patient's symptoms and the results of laboratory examinations.

Neuroblastoma Shown on 18F-DOPA PET/CT Performed to Evaluate Congenital Hyperinsulinism.

ABSTRACT: 18F-DOPA PET/CT was performed to evaluate congenital hyperinsulinism in a 55-day-old boy with hypoglycemia. The images revealed not only a focal 18F-DOPA-avid lesion in the pancreas but also in a left thoracic paraspinal neuroblastoma.

Semi-quantitative assessment optimized the grading of pulmonary aspiration on salivagram in children.

OBJECTIVE: Salivagram is one of the imaging modalities to detect pulmonary aspiration in children. This study aims to optimize the classification of pulmonary aspiration detected by salivagram with a semi-quantitative analytical method. METHODS: This is a retrospective study involving 737 patients (471 males, 266 females; aged 1 month to 8 years; mean age 5.3 months, median age 3.0 months old) with suspected pulmonary aspiration, who had salivagram done between January 2018 and June 2019. Positive cases were divided into 10 groups (Grade 1, R2, L2, R2L2, R3, L3, R3L2, R2L3, R3L3, and 4) according to the scintigraphic findings. Aspiration index was determined as the ratio of the count in the respiratory tract to the total count in the image field of view and compared among different groups using the receiver operating characteristics (ROC) curve analysis. RESULTS: A total of 180 cases had positive scintigraphic findings of various grades of aspiration (24.4%, 180/737). There is a high consistency among the two independent nuclear medicine physicians involved in the study, in determining both the disease gradings (κ = 0.919;95% CI: 0.915-0.923) and aspiration index (ICC = 0.994;95% CI: 0.993-0.996). There is no significant difference (p > 0.05) in aspiration index among the gradings in "mild" group (grade 1, R2, L2, L2R2), and "moderate" group (grade R3, R3L2, R3L3). After dividing the different grades into "mild", "moderate" and "severe" groups, the aspiration index of "mild" group is 4.40 ± 2.01, that of "moderate" group is 16.43 ± 8.20, and that of "severe" group is 46.94 ± 14.81. Difference in groups was statistically significant (p < 0.0001). In ROC curve analysis, AUC of "mild" and "moderate" groups is 0.970 and that of "moderate" and "severe" groups is 0.943; the cut-off value with highest diagnostic efficiency is 6.75 between "mild" and "moderate" groups and 38.00 between "moderate" and "severe" groups. CONCLUSIONS: We introduced a semi-quantitative analytical method in pulmonary aspiration on salivagram, to optimize and supplement to the current classification of pulmonary aspiration.

Correlation of whole-bone marrow dual-time-point 18F-FDG, as measured by a CT-based method of PET/CT quantification, with response to treatment in newly diagnosed multiple myeloma patients.

The practical application of dual-time-point-imaging (DTPI) technique still remains controversial. One of the issues is that current parameters of DTPI quantification suffer from some deficiencies, mainly limited sampling of the diseased sites by confining measurements to specific locations. We aimed to examine the correlation between the percent change from early to delayed scans in whole-bone marrow (WBM) 18F-FDG uptake, as measured by a CT-based method of PET/CT quantification, and response to treatment in multiple myeloma (MM) patients. Pre-treatment 18F-FDG-PET/CT scans of 36 newly diagnosed MM patients were collected in a prospective study at 1 h and 3 h post tracer injection (NCT02187731). A threshold algorithm based on bone Hounsfield units on CT was applied to segment and quantify WBM 18F-FDG uptake. Patients were separated into two treatment groups: high-dose therapy with autologous stem cell transplant (HDT) and non-high dose therapy (non-HDT). The International Response Criteria for MM patients was used to determine each patient's response to treatment. In the HDT group, WBM 18F-FDG uptake increased significantly in patients that had a poor response to treatment, from a median of 1.31 (IQR: 1.13-1.64) at 1 h to a median of 1.85 (1.45-2.10) at 3 h. The median percent change was 37.77% (IQR: 23.47-46.4), with a range of 6.10-50.73 (P = 0.003). However, no significant change in uptake was observed in patients with a complete response (P = 0.24). The same trend was observed for the non-HDT group. WBM uptake of 18F-FDG assessed with dual-time-point imaging may have a role in predicting treatment response in MM.