Prediction of Response to Lu-PSMA Therapy Based on Tumor-to-Kidney Ratio on Pretherapeutic PSMA PET/CT and Posttherapeutic Tumor-Dose Evaluation in mCRPC.

The aim of this study was to analyze the absorbed dose of Lu-PSMA in osseous versus lymphatic metastases in patients with metastatic castration-resistant prostate cancer across therapy cycles and to relate those data to therapeutic success. In addition, pretherapeutic prostate-specific membrane antigen (PSMA) PET/CT was evaluated for its ability to predict response behavior. The study comprised 30 patients with metastatic castration-resistant prostate cancer, each receiving at least 3 cycles of Lu-PSMA therapy.

Translational Development of a Zr-89-Labeled Inhibitor of Prostate-specific Membrane Antigen for PET Imaging in Prostate Cancer.

Purpose: We present here a Zr-89-labeled inhibitor of prostate-specific membrane antigen (PSMA) as a complement to the already established F-18- or Ga-68-ligands.

Procedures: The precursor PSMA-DFO (ABX) was used for Zr-89-labeling. This is not an antibody, but a peptide analogue of the precursor for the production of [Lu]Lu-PSMA-617.

An Zr-Labeled PSMA Tracer for PET/CT Imaging of Prostate Cancer Patients.

The short half-life of existing prostate-specific membrane antigen (PSMA) tracers limits their time for internalization into tumor cells after injection, which is an essential prerequisite for robust detection of tumor lesions with low PSMA expression on PET/CT scans. Because of its longer half-life, the Zr-labeled ligand Zr-PSMA-DFO allows acquisition of PET scans up to 6 d after injection, thereby overcoming the above limitation. We investigated whether Zr-PSMA-DFO allowed more sensitive detection of weak PSMA-positive prostate cancer lesions.

[F]-JK-PSMA-7 PET/CT Under Androgen Deprivation Therapy in Advanced Prostate Cancer.

Purpose: PSMA imaging is frequently used for monitoring of androgen deprivation therapy (ADT) in prostate cancer. In a previous study, [F]-JK-PSMA-7 exhibited favorable properties for tumor localization after biochemical recurrence. In this retrospective study, we evaluated the performance of [F]-JK-PSMA-7 under ADT.

Intraindividual Comparison of F-PSMA-1007 with Renally Excreted PSMA Ligands for PSMA PET Imaging in Patients with Relapsed Prostate Cancer.

F-prostate-specific membrane antigen (PSMA)-1007 is excreted mainly through the liver. We benchmarked the performance of F-PSMA-1007 against 3 renally excreted PSMA tracers. Among 668 patients, we selected 27 in whom PET/CT results obtained with Ga-PSMA-11, F-DCFPyL (2-(3-(1-carboxy-5-[(6-[F]fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid), or F-JK-PSMA-7 (JK, Juelich-Koeln) were interpreted as equivocal or negative or as oligometastatic disease (PET-1).

Biodistribution and radiation dosimetry of [F]-JK-PSMA-7 as a novel prostate-specific membrane antigen-specific ligand for PET/CT imaging of prostate cancer.

Aim: We investigated the whole-body distribution and the radiation dosimetry of [F]-JK-PSMA-7, a novel F-labeled PSMA-ligand for PET/CT imaging of prostate cancer.

Methods: Ten patients with prostate cancer and biochemical recurrence or radiologic evidence of metastatic diseases were examined with 329-384 MBq (mean 359 ± 17 MBq) [F]-JK-PSMA-7. Eight sequential positron emission tomography (PET) scans were acquired from 20 min to 3 h after injection with IRB approval.

An F-Labeled PSMA Ligand for PET/CT of Prostate Cancer: First-in-Humans Observational Study and Clinical Experience with F-JK-PSMA-7 During the First Year of Application.

In preclinical trials, the recently developed tracer 2-methoxy-F-DCFPyL (F-JK-prostate-specific membrane antigen [PSMA]-7) has shown favorable properties regarding clinical performance and radiochemical accessibility. The aim of this study was to evaluate the clinical utility of F-JK-PSMA-7 for PET/CT imaging of patients with prostate cancer. In an Institutional Review Board-approved pilot study, the initial clinical utility of PET/CT imaging with F-JK-PSMA-7 was directly compared with Ga-PSMA-11 PET/CT in a group of 10 patients with prostate cancer.

4D-CT-based motion correction of PET images using 3D iterative deconvolution.

Objectives: Positron emission tomography acquisition takes several minutes representing an image averaged over multiple breathing cycles. Therefore, in areas influenced by respiratory movement, PET-positive lesions occur larger, but less intensive than they actually are, resulting in false quantitative assessment. We developed a motion-correction algorithm based on 4D-CT without the need to adapt PET-acquisition.

[Procedural guideline for Iodine-131 whole-body scintigraphy in differentiated thyroid carcinoma (version 5)].

Version 5 of the procedural guideline for Iodine-131 whole-body scintigraphy (WBS) in differentiated thyroid carcinoma is an update of the version 4, published by the "Deutsche Gesellschaft für Nuklearmedizin" (DGN). This procedural guideline advises on how to best perform I-131 whole body scintigraphy after I-131 therapy or after application of a diagnostic I-131 activity. A representative expert group has discussed and reached consensus on the procedural guideline; the development of this procedural guideline therefore fulfils the criteria for level S1 (first step) within the classification of the German Workgroup of Scientific Medical Societies ("Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften"; AWMF).

Uptake in non-affected bone tissue does not differ between [18F]-DCFPyL and [68Ga]-HBED-CC PSMA PET/CT.

Introduction: [68Ga]PSMA-HBED-CC and [18F]DCFPyL show a high potential for the detection of recurrent prostate cancer. While 18F-based tracers have several advantages in availability and image resolution, their sensitivity in the skeleton might be impaired by released [18F]fluoride due to its high bone affinity. In turn, chemically unbound trivalent 68Ga might also accumulate in osseous tissue, in cases of occupied binding sites of plasma proteins and thereby influence bone signal.

Impact of different approaches to calculation of treatment activities on achieved doses in radioiodine therapy of benign thyroid diseases.

Purpose: Radioiodine has been used for the treatment of benign thyroid diseases for over 70 years. However, internationally, there is no common standard for pretherapeutic dosimetry to optimally define the individual therapy activity. Here, we analyze how absorbed tissue doses are influenced by different approaches to pretherapeutic activity calculation of varying complexity.

Discovery of F-JK-PSMA-7, a PET Probe for the Detection of Small PSMA-Positive Lesions.

Prostate-specific membrane antigen (PSMA), expressed by most prostate carcinomas (PCa), is a promising target for PCa imaging. The application of PSMA-specific F-labeled PET probes such as F-DCFPyL and F-PSMA-1007 considerably improved the accuracy of PCa tumor detection. However, there remains a need for further improvements in sensitivity and specificity.

Thyroid Uptake and Effective Half-Life of Radioiodine in Thyroid Cancer Patients at Radioiodine Therapy and Follow-Up Whole-Body Scintigraphy Either in Hypothyroidism or Under rhTSH.

Adjuvant radioiodine therapy (RITh) for differentiated thyroid carcinoma is performed either with thyroid hormone withdrawal or with administration of recombinant human thyroid-stimulating hormone (rhTSH). Heterogeneous results have been obtained on the impact of the method of patient preparation on thyroid uptake and whole-body effective half-life. A higher radiation exposure using thyroid hormone withdrawal for several weeks compared with rhTSH was reported in prior studies.

Lacrimal Glands May Represent Organs at Risk for Radionuclide Therapy of Prostate Cancer with [(177)Lu]DKFZ-PSMA-617.

Purpose: Calculating the absorbed dose is important for the determination of risk and therapeutic benefit of internal radiation therapy. The aim of this study was to perform image-based absorbed dose calculation for critical organs during the first cycle of [(177)Lu]DKFZ-PSMA-617 therapy in a small cohort of patients with metastatic prostate cancer.

Procedures: Nine patients with a history of prostate cancer documented by histopathology and radiologic evidence of metastatic diseases underwent radioligand therapy with [(177)Lu]DKFZ-PSMA-617.

Semiautomatic algorithm for lymph node analysis corrected for partial volume effects in combined positron emission tomography-computed tomography.

Positron emission tomography-computed tomography (PET-CT) is superior compared to stand-alone PET in evaluation of malignancies. Few studies have employed high-resolution structural information to correct PET. We designed a semiautomatic algorithm using CT and PET to obtain a partial volume corrected (PVC) standardized uptake value (SUV) and a combined morphologic and functional parameter (multimodal SUV) for lymph node assessment.