Iobenguane I-123

This study aims to evaluate the performance of the single time-point (STP) dosimetry model in patients with differentiated thyroid cancer (DTC) or neuroendocrine tumors (NETs) undergoing radioiodine therapy.This approach facilitates personalized dosimetry and optimizes radioiodine therapy for these patients.The study enrolled 18 patients-9 with DTC and 9 with NETs.Each patient underwent three planar imaging sessions at 24, 72, and 168 h following the administration of the resp. radioiodine compoundsThe results from the STP evaluations for each time point were compared to the three-time-point dosimetry measurements to determine the accuracy of the STP model.In DTC patients, using the STP dosimetry at 72 h provided integrated activity estimates for all organs with less than 10% error compared to the reference three-time-point dosimetry, except in the thyroid, where the activity estimation error was 14%.The 168-h STP evaluation yielded an integrated activity estimation in the thyroid remnants with only a 7% error.In NET patients treated with ¹³¹I-MIBG, applying the STP dosimetry at 72 h led to at most a 10% underestimation of activity across all tissues.Addnl., the 168 h STP produced integrated activity estimates in different tissues within a range of +15% to -14% compared to the reference model.The STP dosimetry model demonstrated reliable accuracy for quantifying absorbed doses in various tissues and NET lesions.These findings support the potential of this approach for routine personalized dosimetry in radioiodine therapy.

Hereditary pheochromocytomas and paragangliomas can be associated with mutations in the mitochondrial enzyme succinate dehydrogenase. Due to their heterogenous clinical presentation, no clear universal screening guidelines are currently available. We sought to examine the utility of metabolic testing and imaging in diagnosing hereditary pheochromocytomas and paragangliomas.

Our retrospective study included patients with confirmed familial succinate dehydrogenase mutations and histologically proven pheochromocytomas/paragangliomas or with suggestive metabolic and imaging features. We extracted information on age, race, sex, tumor size, tumor location, presence of metastatic disease and other succinate dehydrogenase-associated manifestations, urine and plasma metabolic testing, and diagnostic imaging. Patients who lacked any diagnostic information were excluded.

Our cohort consisted of 9 patients with 13 tumor occurrences from 2003 to 2023. The average age at diagnosis was 31.7 years with a 2.9 cm average tumor size. Three patients developed metastatic disease. Five tumors (38.5%) were biochemically silent, with all tumors detected on imaging. Most of the remaining tumors had a noradrenergic profile, with positive norepinephrine and normetanephrine in plasma and urine. I-123 MIBG was the least sensitive (50%) imaging modality, and Ga-68 DOTATATE PET/CT was the most sensitive (100%). 10 (76.9%) tumors were treated with surgical resection; all metabolic results were subsequently negative, except in patients with metastatic disease.

Our investigation adds to the current literature on diagnosing hereditary pheochromocytomas and paragangliomas. We highlight the importance of multimodal screening that consists of both imaging and metabolic screening, especially given the prevalence of biochemically silent tumors.