[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 18F-sodium fluoride uptake in the whole bone, pelvis, and femoral neck of multiple myeloma patients before and after high-dose therapy and conventional-dose chemotherapy.

AIM: To compare the effects of high-dose therapy (HDT consisting of high-dose chemotherapy followed by autologous stem cell transplantation) and conventional-dose chemotherapy (non-HDT) on the uptake of 18F-sodium fluoride (NaF) in the whole bone, pelvis, and femoral neck of multiple myeloma (MM) patients. METHOD: The data of 19 MM patients who received HDT (61.5 (SD 5.6) years) and 11 MM patients who received conventional-dose chemotherapy (70.9 (SD 7.2) years) were collected in a prospective study. NaF PET/CT imaging was performed at baseline, and 8 weeks and 2 weeks after treatment for the HDT group and the non-HDT group, respectively. A CT-based algorithm was applied to segment the bones, and the global mean SUV (GSUVmean) of the whole bone and pelvis was calculated (OsiriX MD v.9.0, Pixmeo SARL; Bernex, Switzerland). In addition, regions of interest for the whole, medial, and lateral femoral neck were delineated bilaterally. Whole bone and pelvis measurements were replicated by two observers. RESULTS: The average GSUVmean in the whole bone and pelvis of the patients who underwent HDT significantly decreased from before to after treatment (- 16.27%, p = 0.02 and - 16.54%, p = 0.01, respectively). A significant decrease in the whole and lateral femoral neck was also observed bilaterally in the HDT group. No significant decrease in average GSUVmean was observed in the non-HDT group. A high level of inter-observer reliability was found in intra-class correlation (ICC for pre-treatment whole bone 0.983, post-treatment whole bone 0.989, pre-treatment whole pelvis 0.998, post-treatment whole pelvis 0.996). CONCLUSION: NaF uptake significantly decreased after treatment in patients who received high-dose therapy. A high level of agreement was observed between two operators for whole bone and pelvis measurements.

Effects of age and weight on the metabolic activities of the cervical, thoracic and lumbar spines as measured by fluorine-18 fluorodeoxyglucose-positron emission tomography in healthy males.

OBJECTIVE: This study aimed to explore the age and weight-related metabolic trends in the spines of healthy male subjects using fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) imaging. SUBJECTS AND METHODS: Forty three healthy male subjects (age 23-75 years, weight 50-145kg) were selected from the CAMONA study. A global assessment methodology was applied to the subjects' 18F-FDG 180 minute scans, where each region of the spine (cervical, thoracic and lumbar) was individually encapsulated in a single region of interest, and standardized uptake value (SUVmean) was calculated per respective region. RESULTS: SUVmean increased significantly with weight in both the thoracic spine (Slope=0.0066, P=0.001) and lumbar spine (Slope=0.0087, P<0.0001), but not the cervical spine. There were no significant correlations between age and SUVmean in all three regions. The cervical spine (average SUVmean=1.84±0.31) illustrated elevated activity when compared to the thoracic (average SUVmean=1.46±0.27, P<0.0001) and lumbar (average SUVmean=1.41±0.28, P<0.0001) spines. CONCLUSION: This study illustrated the ability of 18F-FDG PET to assess metabolic processes in the spine. The data provided evidence of weight dependent metabolic activity, likely related to inflammation. This study offers a methodological precedent that can be applied to studies in populations with back pain.

The role of 18F-FDG PET/CT in the evaluation of pediatric transplant patients.

OBJECTIVE: Intensive immunosuppressive regimens effectively reduce acute or chronic rejection in transplant patients, while these regimens can result in long term side-effects such as viral infection, fever, secondary tumor(s) etc. Our aim was to evaluate the role of 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in pediatric transplant patients. SUBJECTS AND METHODS: Forty one (18)F-FDG PET/CT scans in 18 patients before or after transplantation were analyzed retrospectively. One patient had PET/CT scan prior to transplantation. Seventeen patients had PET/CT scan(s) following transplantation. The PET/CT scan was used to evaluate the therapy response of post transplant lymphoproliferative disorder (PTLD) in 11 patients, establish the cause of fever of unknown origin (FUO) in 5 patients, and restage in 2 patients. RESULTS: PET/CT scan showed development in 3 PTLD patients, improvement in 4 PTLD patients, development and improvement in 1 PTLD patient, new lesions in 1 PTLD patient, and no lesions in 2 PTLD patients. The scan demonstrated the cause of FUO in 2 patients but did not demonstrate the cause of FUO in 2 patients. The PET/CT was false positive in 1 FUO patient and did not show any new lesion(s) in 2 restaging patients. CONCLUSION: PET/CT may have an important role in follow-up of pediatric transplant patients. Further investigations with more patients are necessary to assess the validity of our findings.

Patterns of 18F-FDG PET images in patients with uncomplicated total hip arthroplasty.

OBJECTIVE: This retrospective study was carried out to determine the typical patterns of (18)F-FDG uptake in uncomplicated total hip arthroplasty (THA). SUBJECTS AND METHODS: (18)F-FDG-PET images of 62 asymptomatic THA patients who had undergone whole body scanning were evaluated for this retrospective study. The uptake was assessed qualitatively as positive or negative in the head/neck and the stem of the prosthesis. There were 76 hip prosthesis scans (34 left side and 42 right) and the average time following surgery was 75 months (range from 40 days to 372 months). Furthermore, the time course after surgery was subdivided into 3 time interval groups: Group I less than 2 years, Group II between 2 to 5 years, Group III more than 5 years. The regions of assessment were: head region including acetabulum and femoral head, femoral neck, trochanter, and femoral shaft. RESULTS: In patients who demonstrated increased peri-prosthetic (18)F-FDG uptake (59 of the 76 hip scans), the activity was confined to the femoral neck and proximal femoral shaft with the majority in the neck regions alone: 68% (40 of 59). Majority of the uptake was noted in the femoral neck, proximal shaft and trochanteric regions. CONCLUSION: Uptake of (18)F-FDG in the asymptomatic patients with THA is commonly visualized and appears to be confined to the proximal segment of the prosthesis with minimal or no activity in its femoral segment.

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.

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.

When should we recommend use of dual time-point and delayed time-point imaging techniques in FDG PET?

FDG PET and PET/CT are now widely used in oncological imaging for tumor characterization, staging, restaging, and response evaluation. However, numerous benign etiologies may cause increased FDG uptake indistinguishable from that of malignancy. Multiple studies have shown that dual time-point imaging (DTPI) of FDG PET may be helpful in differentiating malignancy from benign processes. However, exceptions exist, and some studies have demonstrated significant overlap of FDG uptake patterns between benign and malignant lesions on delayed time-point images. In this review, we summarize our experience and opinions on the value of DTPI and delayed time-point imaging in oncology, with a review of the relevant literature. We believe that the major value of DTPI and delayed time-point imaging is the increased sensitivity due to continued clearance of background activity and continued FDG accumulation in malignant lesions, if the same diagnostic criteria (as in the initial standard single time-point imaging) are used. The specificity of DTPI and delayed time-point imaging depends on multiple factors, including the prevalence of malignancies, the patient population, and the cut-off values (either SUV or retention index) used to define a malignancy. Thus, DTPI and delayed time-point imaging would be more useful if performed for evaluation of lesions in regions with significant background activity clearance over time (such as the liver, the spleen, the mediastinum), and if used in the evaluation of the extent of tumor involvement rather than in the characterization of the nature of any specific lesion. Acute infectious and non-infectious inflammatory lesions remain as the major culprit for diminished diagnostic performance of these approaches (especially in tuberculosis-endemic regions). Tumor heterogeneity may also contribute to inconsistent performance of DTPI. The authors believe that selective use of DTPI and delayed time-point imaging will improve diagnostic accuracy and interpretation confidence in FDG PET imaging.

Delayed small bowel transit in children with cystic fibrosis and pancreatic insufficiency.

OBJECTIVE: Gastrointestinal disturbances are common in people with cystic fibrosis (CF); however, motility studies in this population have yielded inconsistent results. This study examined gastric emptying (GE) and small bowel transit (SBT) time in children with CF and pancreatic insufficiency compared with a healthy adult reference group. METHODS: Participants consumed an 8-ounce liquid test meal (approximately 550 calories, 32 g of fat) labeled with 300 µCi 99m technetium (Tc) sulfur colloid. Subjects with CF received a standard dose of pancreatic enzymes before consuming the test meal. GE and SBT were measured using a standard nuclear medicine scan. GE was determined after correcting for 99mTc decay in both anterior and posterior images. SBT was determined by following the movement of the tracer from the stomach to the cecum. The percentage arrival of total small bowel activity at the terminal ileum and cecum/ascending colon at 6 hours was used as an index of SBT. A 1-way analysis of covariance was performed for comparisons between groups after adjustment for age, sex, and body mass index. RESULTS: Subjects with CF (n = 16) had similar GE compared with the healthy reference group (n = 12); however, subjects with CF had significantly prolonged SBT time. At 6 hours, 37.2% ± 25.4% (95% CI 23.7-50.7) of the tracer reached the terminal ileum and colon compared with 68.6% ± 13.1% (95% CI 60.2-76.9) for the reference group (P < 0.001). After controlling for sex, age, and body mass index, this difference remained statistically significant (F = 12.06, adjusted R = 0.44, P < 0.002). CONCLUSIONS: Children with CF and pancreatic insufficiency had unaltered GE but delayed SBT time when taking pancreatic enzymes.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.