Purpose: Primary staging of prostate cancer relies on modalities, which are limited. We evaluate simultaneous [68Ga]Ga-PSMA-11 PET (PSMA-PET)/MRI as a new diagnostic method for primary tumor–node–metastasis staging compared with histology and its impact on therapeutic decisions. Experimental Design: We investigated 122 patients with PSMA-PET/MRI prior to planned radical prostatectomy (RP). Primary endpoint was the accuracy of PSMA-PET/MRI in tumor staging as compared with staging-relevant histology. In addition, a multidisciplinary team reassessed the initial therapeutic approach to evaluate its impact on the therapeutic management. Results: PSMA-PET/MRI correctly identified prostate cancer in 119 of 122 patients (97.5%). Eighty-one patients were treated with RP and pelvic lymphadenectomy. The accuracy for T staging was 82.5% [95% confidence interval (CI), 73–90; P < 0.001], for T2 stage was 85% (95% CI, 71–94; P < 0.001), for T3a stage was 79% (95% CI, 43–85; P < 0.001), for T3b stage was 94% (95% CI, 73–100; P < 0.001), and for N1 stage was 93% (95% CI, 84–98; P < 0.001). PSMA-PET/MRI changed the therapeutic strategy in 28.7% of the patients with either the onset of systemic therapy/radiotherapy (n = 16) or active surveillance (n = 19). Conclusions: PSMA-PET/MRI can provide an accurate staging of newly diagnosed prostate cancer. In addition, treatment strategies were changed in almost a third of the patients due to the information of this hybrid imaging technique.

Radiation therapy is one of the most effective tools in cancer therapy. However, success varies individually, necessitating improved understanding of radiobiology. Three-dimensional (3D) tumor spheroids are increasingly gaining attention, being a superior in vitro cancer model compared to 2D cell cultures. This in vitro study aimed at comparing radiation responses in 2D and 3D cell culture models of different human cancer cell lines (PC-3, LNCaP and T-47D) irradiated with varying doses (1, 2, 4, 6, 8 or 20 Gy) of X-ray beams. Radiation response was analyzed by growth analysis, various cell viability assays (e.g., clonogenic assay, resazurin assay) and amount of DNA damage (γH2AX Western Blot). Results showed decreasing cell proliferation with the increase of radiation doses for all cell lines in monolayers and spheroids of LNCaP and T-47D. However, significantly lower radiosensitivity was detected in spheroids, most pronounced in PC-3, evincing radiation resistance of PC-3 spheroids up to 8 Gy and significant growth inhibition only by a dose escalation of 20 Gy. Cell line comparison showed highest radiosensitivity in LNCaP, followed by T-47D and PC-3 in 2D, whereas, in 3D, T-47D showed highest sensitivity. The results substantiate the significant differences in radiobiological response to X-rays between 2D and 3D cell culture models.

This continuing educational article gives an introduction to radiochemistry of positron emission tomography (PET)-tracers, which exhibit a covalently bound radiolabel with the nuclides carbon-11, nitrogen-13, and fluorine-18. The overall process of a PET-tracer production is explained starting from the production of the radionuclide in a cyclotron, followed by the automatization process of the radiosynthesis including the necessary steps for the respective synthesis and finalized with the requirements for quality control.

Electroconvulsive therapy (ECT) constitutes one of the most effective antidepressant treatment strategies in major depression (MDD). Despite its common use and uncontested efficacy, its mechanism of action is still insufficiently understood. Previously, we showed that ECT is accompanied by a global decrease of serotonin-1A receptors in MDD; however, further studies to investigate the involvement of the serotonergic system in the mechanism of action of ECT are warranted. The monoamine oxidase A (MAO-A) represents an important target for antidepressant treatments and was found to be increased in MDD. Here, we investigated whether ECT impacts on MAO-A levels in treatment-resistant patients (TRD). 16 TRD patients (12 female, age 45.94 ± 9.68 years, HAMD 25.12 ± 3.16) with unipolar depression according to DSM-IV were scanned twice before (PET1 and PET2, to assess test-retest variability under constant psychopharmacotherapy) and once after (PET3) completing a minimum of eight unilateral ECT sessions using positron emission tomography and the radioligand [11C]harmine to assess cerebral MAO-A distribution volumes (VT). Age- and sex-matched healthy subjects (HC) were measured once. Response rate to ECT was 87.5%. MAO-A VT was found to be significantly reduced after ECT in TRD patients (-3.8%) when assessed in 27 a priori defined ROIs (p < 0.001). Test-retest variability between PET1 and PET2 was 3.1%. MAO-A VT did not significantly differ between TRD patients and HC at baseline. The small effect size of the significant reduction of MAO-A VT after ECT in the range of test-retest variability does not support the hypothesis of a clinically relevant mechanism of action of ECT based on MAO-A. Furthermore, in contrast to studies reporting elevated MAO-A VT in unmedicated depressed patients, MAO-A levels were found to be similar in TRD patients and HC which might be attributed to the continuous antidepressant pharmacotherapy in the present sample.

Radiolabeling of the chemotherapeutic agent BOLD-100 with ruthenium-103 enables animal experiments with lower amounts of injected drug. This leads to a relatively higher tumor uptake and promising tumor-to-background ratio for future imaging studies.

The overexpression of the translocator protein (TSPO) has been amply reported for a variety of conditions, including neurodegenerative disorders, heart failure, and cancer. Thus, TSPO has been proposed as an excellent imaging biomarker, allowing, in this manner, to obtain an accurate diagnosis and to follow disease progression and therapy response. Accordingly, several radioligands have been developed to accomplish this purpose. In this work, we selected [¹⁸F]FEPPA, as one of the clinical established tracers, and assessed its in vitro performance in colorectal cancer. Moreover, we setup an improved radiosynthesis method and assessed the in vitro binding affinity of the nonradioactive ligand toward the human TSPO. Our results show an excellent to moderate affinity, in the subnanomolar and nanomolar range, as well as the suitability of [¹⁸F]FEPPA as an imaging agent for the TSPO in colorectal cancer.