Efficacy and Safety of 124I-MIBG Dosimetry-Guided High-Activity 131I-MIBG Therapy of Advanced Pheochromocytoma or Neuroblastoma.

We aim to evaluate the efficacy and safety of 124I-metaiodobenzylguanidine (MIBG) dosimetry-guided high-activity 131I-MIBG therapy of advanced pheochromocytoma or neuroblastoma. Methods: Fourteen patients with advanced pheochromocytoma or neuroblastoma, age 9-69 y, underwent 124I-MIBG PET scans and whole-body retention measurements to assess the whole-body dose as a surrogate of bone marrow toxicity and tumor (absorbed) dose per unit of administered activity. Dosimetry results together with individual patient characteristics were combined to guide a single therapeutic activity to achieve a high tumor dose without exceeding toxicity threshold. Toxicity was assessed for hematologic, hepatic, and renal function. Response was evaluated by RECIST, International Society of Pediatric Oncology Europe Neuroblastoma-like score, change in PET uptake, and quantitative PET parameters (SUVmax, SUVpeak, metabolic tumor volume, total lesion glycolysis), as well as visual decrease in number or in visual intensity of lesions on baseline to follow-up 124I-MIBG PET/CT. Results: The average therapeutic activity was 14 GBq. Eleven of 14 patients (79%) received each more than 10 GBq. One male patient was treated with a single activity of 50 GBq. Three patients were treated with lower activities between 3.5 and 7.0 GBq. Median overall survival was 85 mo (95% CI), and median progression-free survival was 25 mo (95% CI). Four (29%) and 5 (36%) patients demonstrated response (complete response or partial response) by RECIST and functional imaging, respectively. One patient exceeded whole-body dose of 2 Gy and demonstrated grade 3 hematologic toxicity, which resolved spontaneously within 12 mo after the therapy without the need for further treatment. Three patients (21%) demonstrated transient grade 1 renal toxicity. Conclusion: 124I-MIBG dosimetry-guided high-activity 131I-MIBG therapy in patients with advanced pheochromocytoma or neuroblastoma resulted in durable responses with a low rate of manageable adverse events. Efficacy of 124I-MIBG-guided activity escalation should further be assessed in a prospective setting.

Novel 68Ga-FAPI PET/CT Offers Oncologic Staging Without COVID-19 Vaccine-Related Pitfalls.

In the setting of ongoing coronavirus disease 2019 vaccination, vaccine-related tracer uptake in locoregional lymph nodes has become a well-known issue in tumor staging by 18F-FDG PET/CT. 68Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT is a new oncologic imaging tool that may overcome this limitation. Methods: We assessed postvaccine head-to-head and same-day 18F-FDG and 68Ga-FAPI-46 PET/CT findings in a series of 11 patients from a large, prospective imaging registry. All patients with documented tracer uptake in locoregional lymph nodes on PET/CT or PET/MRI, after vaccination within 6 wk, were eligible for investigation. Result: Significant visual lymph node uptake adjacent to the injection site was noted in 11 of 11 (100%) patients with 18F-FDG PET/CT, versus 0 of 11 (0%) with 68Ga-FAPI PET/CT. 18F-FDG detected 73% and 68Ga-FAPI PET/CT 94% of all tumor lesions. Conclusion: In this case-series study, 68Ga-FAPI showed its potential to avoid 18F-FDG PET/CT postvaccination pitfalls and presented superior tumor localization.

FDG-PET Positivity and Overall Survival in Renal Cell Carcinoma.

This cohort study examines positron emission tomography in renal cell carcinoma and its association with overall survival among adults.

Diagnostic Performance of 124I-Metaiodobenzylguanidine PET/CT in Patients with Pheochromocytoma.

123/131I-metaiodobenzylguanidine (MIBG) scintigraphy has shown a high specificity for imaging pheochromocytoma and paraganglioma, but with low sensitivity because of low spatial resolution. 124I-MIBG PET may be able to overcome this limitation and improve the staging of patients with (suspected) pheochromocytoma. Methods: We analyzed the sensitivity, specificity, and positive and negative predictive values of 124I-MIBG PET in 43 consecutive patients with suspected (recurrence of) pheochromocytoma using histopathologic (n = 25) and clinical validation (n = 18) as the standard of truth. Furthermore, we compared the detection rate of 124I-MIBG PET versus contrast-enhanced (CE) CT on a per-patient and per-lesion basis in 13 additional patients with known metastatic malignant pheochromocytoma. Results:124I-MIBG PET/CT was positive in 19 (44%) of 43 patients with suspected pheochromocytoma. The presence of pheochromocytoma was confirmed in 22 (51%) of 43. 124I-MIBG PET/CT sensitivity, specificity, and positive and negative predictive values were 86%, 100%, 100%, and 88%, respectively. 124I-MIBG PET was positive in 11 (85%) of 13 patients with malignant pheochromocytoma. Combined 124I-MIBG PET and CE CT detected 173 lesions, of which 166 (96%) and 118 (68%) were visible on 124I-MIBG PET and CE CT, respectively. Conclusion:124I-MIBG PET detects pheochromocytoma with high accuracy at initial staging and a high detection rate at restaging. Future assessment of 124I-MIBG PET for treatment guidance, including personalized 131I-MIBG therapy, is warranted.

Post-radiosynovectomy imaging utilizing Erbium-169 citrate.

Currently, there is no imaging procedure for radionuclide therapy utilizing Erbium-169 (Er-169). We have recently published the first post-radiosynovectomy imaging of Er-169 citrate in a case report (Farahati et al., 2017). In this study, we performed in-vitro and in-vivo studies to evaluate the feasibility to assess the distribution of Er-169 citrate after radiosynovectomy in fourteen patients with seventeen affected joints treated for refractory chronic synovitis. Post-radiosynovectomy imaging revealed the feasibility of post-radiosynovectomy detection and distribution utilizing Er-169 citrate in all cases. However, additional in-vitro studies including in-vitro imaging, gamma spectrometry and analysis of half-life indicated that emitted gamma-rays of the Ytterbium-169 in the radiopharmaceutical together with bremsstrahlung induced by Er-169 are the imaging source of emitted counts. Post-radiosynovectomy imaging utilizing Er-169 citrate is feasible and should be implemented in the guidelines for theranostics for quality control, patient safety and therapy monitoring.

Changing trends of incidence and prognosis of thyroid carcinoma.

AIM: to evaluate the time trend of epidemiology of follicular cell derived thyroid cancer (TC) based on data from a well documented cancer registry. METHODS: Population based data on TC from Lower Franconia (LF), Germany, within 1981 and 2015 were analysed to estimate the regional epidemiology of TC. The incidence was assessed in 5-year-intervals for gender, histology, and tumor stage. RESULTS: Incidence of TC solely attributable to papillary TC (PTC) doubled mainly in T1- and T2-stages within the evaluation period from 4.5 to 8.7/100.000/y in females and 1.7 to 4.1/100.000/y in males. There was no significant change of follicular TC (FTC), whereas anaplastic TC (ATC) decreased in the same interval. The number of lymph-node metastases and T3-cases increased, while the frequency of T4-stage and distant metastases decreased. Increased incidences of T1- and T2-stages suggest an over-diagnosis. In contrast, increasing number of tumors at T3-stage and with lymph node involvement contradict the over-diagnosis as the only reason for rising incidence. Declining of T4-stages in spite of increasing of T3-stages and N1-cases indicates the value of timely detection and treatment of TC. In accordance, reduced incidence of advanced cancers with M1-stage and ATC cases promote our current management of TC. CONCLUSION: Timely diagnosis and adequate risk-adopted treatment of thyroid cancer reduce the frequency of high-risk cases with distant metastases and the possible protracted dedifferentiation of TC to anaplastic features. Our analyses support the management algorithm in thyroid cancer according to the recent guidelines of German Nuclear Medicine Society.