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Background: The main objective is to discuss why treatment of non-prostate cancers with [177Lu]Lu-PSMA-radioligand achieved only low tumor dose in most published cases, despite high uptake on PSMA PET. We use a patient with renal cell carcinoma as an illustrative example. Furthermore, we discuss how the problem with early washout and low tumor dose might be overcome by using a radionuclide with shorter half-life, matching the target binding residence time. Case presentation: [68Ga]Ga-PSMA-11 PET/CT of a 56-year old man with metastatic renal cell carcinoma showed high lesion uptake. One dose of 6.9 GBq [177Lu]Lu-PSMA-I&T was administrated. Post-therapy dosimetry was performed with SPECT/CT and whole-body planar imaging after 5, 24 and 48 h. Doses to target lesions were only 0.2–0.5 Gy. No treatment effect was achieved. Conclusion: Rapid tumor washout of [177Lu]Lu-PSMA-I&T and low tumor dose despite high uptake of [68Ga]Ga-PSMA-11 are most likely caused by localization of PSMA-receptors on neovasculature rather than on the tumor cells, and unlike in prostate cancer cells, the PSMA-RL / PSMA-receptor complex is not internalized. To overcome the problem with early washout, the use of a radionuclide with shorter half-life matching the target binding residence time will be needed. [ABSTRACT FROM AUTHOR]

Objective: Redifferentiation therapy (RDT) can restore radioactive iodine (RAI) uptake in differentiated thyroid cancer (DTC) cells to enable salvage 131I therapy for previously RAI refractory (RAIR) disease. This study evaluated the clinical outcomes of patients who underwent RDT and identified clinicopathologic characteristics predictive of RAI restoration following RDT. Methods: This is a retrospective case series of 33 patients with response evaluation criteria in solid tumors (RECIST)-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic (Rochester, MN). All patients underwent genomic profiling and received MEK, RET or ALK inhibitors alone, or combination BRAF-MEK inhibitors for 4 weeks. At week 3, those with increased RAI avidity in metastatic foci received high-dose 131I therapy. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 57.6% had restored RAI uptake following RDT (Redifferentiated subgroup). 42.1% (8/19) with papillary thyroid cancers (PTC), 100% (4/4) with invasive encapsulated follicular variant PTCs (IEFV-PTCs), and 100% (7/7) with follicular thyroid cancers (FTC) redifferentiated. All (11/11) RAS mutant tumors redifferentiated compared with 38.9% (7/18) with BRAF mutant disease (6 PTC and 1 IEFV-PTC). 76.5% (13/17) of redifferentiated and 66.7% (8/12) of non-redifferentiated patients achieved a best overall RECIST response of stable disease (SD) or non-complete response/non-progressive disease. Both subgroups had a median 12% tumor shrinkage at 3 weeks on drug(s) alone. The redifferentiated subgroup, following high-dose 131I therapy, achieved an additional median 20% tumor reduction at 6 months after RDT. There were no statistically significant differences between both groups in progression free survival (PFS), time to initiation of systemic therapy, and time to any additional therapy. Of the entire cohort, 6.1% (2/33) experienced histologic transformation to anaplastic thyroid cancer, 15.1% (5/33) died, and all had redifferentiated following RDT and received 131I therapy. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following 131I therapy in select patients with RAIR-DTC, particularly those with RAS-driven "follicular" phenotypes. In patients with PTC, none of the evaluated clinical outcomes differed statistically between the redifferentiated and non-redifferentiated subgroups. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic anaplastic transformation. [ABSTRACT FROM AUTHOR]

B Dear Editor: b To our knowledge, all studies on radioiodine redifferentiation after pretreatment with mitogen-activated protein kinase (MAPK) inhibition so far have reported on only one treatment.[1] Although one case report indicates that repeat redifferentiation may be possible, the effects of the redifferentiation could not be assessed because of the simultaneous and continued long treatment with redifferentiation agents.[2] In this letter, we report on a patient with SP 131 sp I refractory (RAIR) BRAF SP V600E sp mutated progressive metastatic papillary thyroid cancer (PTC) successfully redifferentiated twice 14 months apart with the BRAF inhibitor dabrafenib, each followed by SP 131 sp I therapy resulting in initial clinical response. Fourteen months after the treatment, a diagnostic rhTSH-stimulated SP 123 sp I whole-body scan (WBS) and SPECT/CT did not show radioiodine uptake in the metastases (Fig. [Extracted from the article]

Abstract: Objective: To explore the value of 18F fluorodeoxy-glucose (FDG) positron emission tomography (PET) in Burkitt''s lymphoma. Methods: All Burkitt''s lymphoma patients referred for FDG PET or FDG PET/computed tomography (CT) exams at our institution from June 2003 to June 2006 were included. Selected patients were followed and clinical information was reviewed retrospectively. Results from FDG PET–PET/CT, as blindly reviewed by a consensus of two experienced readers, were compared with the status of the disease as determined by other laboratory, clinical and imaging exams and clinical follow-up. FDG PET–PET/CT results were classified as true positive or negative and false positive or negative. The degree of FDG uptake in the positive lesions was semiquantified as maximum standard uptake value (SUVmax). Results: Fifty-seven FDG PET–PET/CT exams were done in 15 patients. Seven exams were done for initial staging, 8 during and 14 after the completion of therapy, and 28 for disease surveillance. For nodal disease FDG PET–PET/CT was true positive in 8, true negative in 47 and false positive in 2 exams (sensitivity 100%, specificity 96%). For extranodal disease FDG PET–PET/CT was true positive in 6, true negative in 48 and false positive in 3 exams (sensitivity 100%, specificity 94%). The mean SUVmax for the positive nodal lesions was 15.7 (range 6.9–21.7, median 18.5) and for extranodal lesions was 14.2 (range 6.2–24.3, median 12.4). Conclusions: FDG PET–PET/CT is sensitive for the detection of viable disease in Burkitt''s lymphoma. Affected areas demonstrated high degree of uptake that was reversible upon successful implementation of treatment. [Copyright &y& Elsevier]

Objective: The purpose of this study is to determine the efficacy of 11 C-choline PET/CT for the detection of parathyroid adenomas by retrospectively reviewing a large patient population., Materials and Methods: In this single-institution retrospective study, 7088 11 C-choline PET/CT scans performed of 2933 men with prostate cancer from January 2005 through February 2016 were evaluated. Patients with suspected parathyroid adenomas were identified through a review of the electronic medical record and relevant imaging. Patient demographics, laboratory results, and lesion characteristics were noted. Pathologically proven parathyroid adenomas and lesions in patients with imaging or laboratory findings consistent with the diagnosis were considered positive., Results: Thirteen men (mean [± SD] age, 72 ± 7 years) with pathologically or laboratory-proven parathyroid adenomas were identified. All had abnormally elevated serum calcium and parathyroid hormone levels. All adenomas were tracer avid on 11 C-choline PET/CT (maximum standardized uptake value, 5.6 ± 3.0), with activity averaging 4.2 times that of the blood pool and 2.1 times that of the adjacent thyroid. One case of an ectopic adenoma was identified. Of the six pathologically confirmed cases, none displayed high-grade features such as capsular, vascular, or adjacent tissue invasion. Three additional patients with possible parathyroid adenomas at 11 C-choline PET/CT were ultimately found to have thyroid lesions on the basis of tissue diagnosis; however, none of these patients had abnormal calcium or parathyroid hormone levels., Conclusion: In our patient population, 11 C-choline PET/CT identified parathyroid adenomas with high specificity. Prospective investigation is warranted to validate this result and delineate the utility of 11 C-choline PET/CT relative to other modalities.

In vitro gastrointestinal (GI) bleed testing such as the UltraTag kits has been successfully used for a number of years. None of the research studies identified reported any significant bone marrow and liver uptake. An 80-y-old male patient was admitted to the hospital for rectal bleeding. An initial GI bleed study using the UltraTag kit was normal. Two days later, a second GI bleed scan was performed while the patient was undergoing blood transfusion with packed red blood cells. The technologist withdrew a blood sample from the blood transfusion bag. The second GI bleed test demonstrated unusual liver and bone marrow uptake. We believe that this liver uptake might have been caused by the labeling of fragmented red blood cells or oxidation of pertechnetate in the form of technetium dioxide.