Phantom study for 90Y post-treatment dosimetry with a long axial field-of-view PET/CT

Purpose: The physical properties of yttrium-90 (90Y) allow for imaging with positron emission tomography/computed tomography (PET/CT). The increased sensitivity of long axial field-of-view (LAFOV) PET/CT scanners possibly allows to overcome the small branching ratio for positron production from 90Y decays and to improve for the post-treatment dosimetry of 90Y of selective internal radiation therapy. Methods: For the challenging case of an image quality body phantom, we compare a full Monte Carlo (MC) dose calculation with the results from the two commercial software packages Simplicit90Y and Hermes. The voxel dosimetry module of Hermes relies on the 90Y images taken with a LAFOV PET/CT, while the MC and Simplicit90Y dose calculations are image independent. Results: The resulting doses from the MC calculation and Simplicit90Y agree well within the error margins. The image-based dose calculation with Hermes, however, consistently underestimates the dose. This is due to the mismatch of the activity distribution in the PET images and the size of the volume of interest. Furthermore, there are likely limitations of Hermes' dose calculation algorithm for 90Y. We found that only for the smallest phantom sphere there is a statistically significant dependence of the Hermes dose on the image reconstruction parameters and scan time. Conclusion: Our study shows that Simplicit90Y's local deposition model can provide a reliable dose estimate. On the other hand, the image based dose calculation requires further benchmarks and verification in order to take full advantage of LAFOV PET/CT systems

Comparison of four radiofrequency ablation systems at two target volumes in an ex vivo bovine liver model

PURPOSEWe aimed to validate actually achieved macroscopic ablation volumes in relation to calculated target volumes using four different radiofrequency ablation (RFA) systems operated with default settings and protocols for 3 cm and 5 cm target volumes in ex vivo bovine liver.MATERIALS AND METHODSSixty-four cuboid liver specimens were ablated with four commercially available RFA systems (Radionics Cool-tip, AngioDynamic 1500X, Boston Scientific RF 3000, Celon CelonPower LAB): 16 specimens for each system; eight for 3 cm, and eight for 5 cm. Ablation diameters were measured, volumes were calculated, and RFA times were recorded.RESULTSFor the 3 cm target ablation volume, all tested RFA systems exceeded the mathematically calculated volume of 14.14 cm3. For the 3 cm target ablation volume, mean ablation volume and mean ablation time for each RFA system were as follows: 28.5±6.5 cm3, 12.0±0.0 min for Radionics Cool-tip; 17.1±4.9 cm3, 9.36±0.63 min for AngioDynamic 1500X; 29.7±11.7 cm3, 4.60±0.50 min for Boston Scientific RF 3000; and 28.8±7.0 cm3, 20.85±0.86 min for Celon CelonPower LAB. For the 5 cm target ablation volume, Radionics Cool-tip (48.3±9.9 cm3, 12.0±0.0 min) and AngioDynamic 1500X (39.4±16.2 cm3, 19.59±1.13 min) did not reach the mathematically calculated target ablation volume (65.45 cm3), whereas Boston Scientific RF 3000 (71.8±14.5 cm3, 9.15±2.93 min) and Celon CelonPower LAB (93.9±28.1 cm3, 40.21±1.78 min) exceeded it.CONCLUSIONWhile all systems reached the 3 cm target ablation volume, results were variable for the 5 cm target ablation volume. Only Boston Scientific RF 3000 and Celon CelonPower LAB created volumes above the target, whereas Radionics Cool-tip and AngioDynamic 1500X remained below the target volume. For the 3 cm target ablation volume, AngioDynamic 1500X with 21% deviation was closest to the target volume. For the 5 cm target volume Boston Scientific RF 3000 with 10% deviation was closest

Translational assessment of a DATA-functionalized FAP inhibitor with facile 68Ga-labeling at room temperature.

PURPOSE The present study aims at evaluating the preclinical and the clinical performance of [68Ga]Ga-DATA5m.SA.FAPi, which has the advantage to be labeled with gallium-68 at room temperature. METHODS [68Ga]Ga-DATA5m.SA.FAPi was assessed in vitro on FAP-expressing stromal cells, followed by biodistribution and in vivo imaging on prostate and glioblastoma xenografts. Moreover, the clinical assessment of [68Ga]Ga-DATA5m.SA.FAPi was conducted on six patients with prostate cancer, aiming on investigating, biodistribution, biokinetics, and determining tumor uptake. RESULTS [68Ga]Ga-DATA5m.SA.FAPi is quantitatively prepared in an instant kit-type version at room temperature. It demonstrated high stability in human serum, affinity for FAP in the low nanomolar range, and high internalization rate when associated with CAFs. Biodistribution and PET studies in prostate and glioblastoma xenografts revealed high and specific tumor uptake. Elimination of the radiotracer mainly occurred through the urinary tract. The clinical data are in accordance with the preclinical data concerning the organ receiving the highest absorbed dose (urinary bladder wall, heart wall, spleen, and kidneys). Different to the small-animal data, uptake of [68Ga]Ga-DATA5m.SA.FAPi in tumor lesions is rapid and stable and tumor-to-organ and tumor-to-blood uptake ratios are high. CONCLUSION The radiochemical, preclinical, and clinical data obtained in this study strongly support further development of [68Ga]Ga-DATA5m.SA.FAPi as a diagnostic tool for FAP imaging

Integration of CT urography improves diagnostic confidence of 68Ga-PSMA-11 PET/CT in prostate cancer patients

Background: To prove the feasibility of integrating CT urography (CTU) into 68Ga-PSMA-11 PET/CT and to analyze the impact of CTU on assigning focal tracer accumulation in the ureteric space to either ureteric excretion or metastatic disease concerning topographic attribution and diagnostic confidence. Methods: Ten prostate cancer patients who underwent 68Ga-PSMA-11 PET/CT including CTU because of biochemical relapse or known metastatic disease were retrospectively analyzed. CTU consisted of an excretory phase 10 min after injection of 80 mL iodinated contrast material. Ureter opacification at CTU was evaluated using the following score: 0, 0% opacification; 1, < 50%; 2, 50–99%; 3, 100%. Topographic attribution and confidence of topographic attribution of focal tracer accumulation in the ureteric space were separately assessed for 68Ga-PSMA-11 PET/CT without and with CTU. Diagnostic confidence was evaluated using the following score: 0, < 25% confidence; 1, 26–50%; 2, 51–75%; 3, 76–100%. Results: At CTU, mean ureter opacification score was 2.6 ± 0.7. At 68Ga-PSMA-11 PET/CT without CTU, mean confidence of topographic attribution of focal tracer accumulation was 2.5 ± 0.7 in total and 2.6 ± 0.7 for metastatic disease. At 68Ga-PSMA-11 PET/CT with CTU, mean confidence of topographic attribution of focal areas of tracer accumulation was significantly higher with 2.9 ± 0.2 in total and 2.7 ± 0.9 for metastatic disease (p < 0.001). In 4 of 34 findings (12%) attribution to either ureteric excretion or metastatic disease was discrepant between 68Ga-PSMA-11 PET/CT without and with CTU (n.s). Conclusions: Integration of CTU into 68Ga-PSMA-11 PET/CT is feasible and increases diagnostic confidence of assigning focal areas of tracer accumulation in the ureteric space to either metastatic disease or ureteric excretion

Static and dynamic 68Ga-FAPI PET/CT for the detection of malignant transformation of intraductal papillary mucinous neoplasia of the pancreas.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) may arise from intraductal papillary-mucinous neoplasms (IPMN) with malignant transformation, but a significant portion of IPMN remains to show benign behavior. Therefore, it is important to differentiate between benign IPMN and IPMN lesions undergoing malignant transformation. However, non-operative differentiation by ultrasound, CT, MRI and carbohydrate antigen 19-9 (CA19-9) is still unsatisfactory. Here, we assessed the clinical feasibility of additional assessment of malignancy by positron emission tomography using 68Gallium-labeled Fibroblast Activation Protein Inhibitors (68Ga-FAPI-PET) in 25 patients with magnetic resonance imaging (MRI) - or computed tomography (CT) - proven cystic pancreatic lesions. Methods: 25 patients with cystic pancreatic lesions who were followed up in the European Pancreas Center of Heidelberg University hospital and who were led to surgical resection or fine needle aspiration (FNA) due to suspicious clinical, laboratory chemistry or radiological findings were examined by static (all patients) and dynamic (20 patients) 68Ga-FAPI-PET. Cystic pancreatic lesions were delineated and maximum and mean standardized uptake values (SUVmax / SUVmean) were determined. Time activity curves and dynamic parameters (time to peak, K1, k2, K3, k4) were extracted from dynamic PET data. Receiver operating curves (ROC) of static and dynamic PET parameters were calculated. Results: 11 of the patients suffered from menacing IPMN (high grade IPMN with (6 cases) or without (5 cases) progression into PDAC) and 11 from low grade IPMN, 3 patients from other benign entities. Menacing IMPN showed significantly elevated 68Ga-FAPI uptake compared to low grade IPMN and other benign cystic lesions. In dynamic imaging, menacing IPMN showed increasing time activity curves (TAC) followed by slow decrease afterwards, TAC of low grade IPMN showed an immediate peak followed by rapid decrease for about 10 minutes and slower decrease for the rest of the time. ROC curves showed high sensitivity and specificity (area under the curve (AUC) greater than 80%) of static and dynamic PET parameters for the differentiation of IPMN subtypes. Conclusion: 68Ga-FAPI-PET is a helpful new tool for the differentiation of menacing and low grade IPMN and shows the potential to avoid unnecessary surgery for non-malignant pancreatic IPMN

Fluid preinjection for microwave ablation in an ex vivo bovine liver model assessed with volumetry in an open MRI system

PURPOSEWe aimed to detect possible differences in microwave ablation (MWA) volumes after different fluid preinjections using magnetic resonance imaging (MRI).MATERIALS AND METHODSMWA volumes were created in 50 cuboid ex vivo bovine liver specimens (five series: control [no injection], 10 mL water, 10 mL 0.9% NaCl, 10 mL 6% NaCl, and 10 mL 12% NaCl preinjections; n=10 for each series). The operating frequency (915 megahertz), ablation time (7 min), and energy supply (45 watts) were constant. Following MWA, two MR sequences were acquired, and MR volumetry was performed for each sequence.RESULTSFor both sequences, fluid preinjection did not lead to significant differences in MWA ablation volumes compared to the respective control group (sequence 1: mean MWA volumes ranged from 7.0±1.2 mm [water] to 7.8±1.3 mm [12% NaCl] vs. 7.3±2.1 mm in the control group; sequence 2: mean MWA volumes ranged from 4.9±1.4 mm [12% NaCl] to 5.5±1.9 mm [0.9% NaCl] vs. 4.7±1.6 mm in the control group). The ablation volumes visualized with the two sequences differed significantly in general (P < 0.001) and between the respective groups (control, P ≤ 0.001; water, P < 0.001; 0.9% NaCl, P < 0.001; 6% NaCl, P ≤ 0.001; 12% NaCl, P < 0.001). The volumes determined with sequence 1 were closer to the expected ablation volume of 8 mL compared to those determined with sequence 2.CONCLUSIONFor the fluid qualities and concentrations assessed, there is no evidence that fluid preinjection results in larger coagulation volumes after MWA. Because ablation volumes determined by MRI vary with the sequence used, interventionalists should gain experience in how to interpret postinterventional imaging findings (with the MR scanner, sequences, and parameters used) to accurately estimate the outcome of the interventions they perform

The theranostic optimization of PSMA-GCK01 does not compromise the imaging characteristics of [99mTc]Tc-PSMA-GCK01 compared to dedicated diagnostic [99mTc]Tc-EDDA/HYNIC-iPSMA in prostate cancer

DATA AVAILABILITY : The data used and/or analyzed during the current study are available from the corresponding author on reasonable request.Please read abstract in the article.Open Access funding enabled and organized by Projekt DEAL. This work was supported by Telix Pharmaceuticals Limited.https://www.springer.com/journal/11307hj2024Nuclear MedicineSDG-03:Good heatlh and well-bein

Prior therapies as prognostic factors of overall survival in metastatic castration-resistant prostate cancer patients treated with [177Lu] Lu-PSMA-617. A WARMTH multicenter study (the 617 trial)

Please read abstract in the article.This article is part of the Topical Collection on Oncology - GenitourinaryOpen Access funding provided by Projekt DEAL.http://link.springer.com/journal/259am2021Nuclear Medicin

Validation of interventional thermal ablation techiques and its visualisation using an open 1 Tesla MRI system

Thermoablationsverfahren wie die Radiofrequenzablation und Mikrowellenablation werden in der Therapie von Primärtumoren und Metastasen in Organen und Knochen eingesetzt. Die initial vollständige Tumorablation ist für die weitere Prognose der Erkrankung von besonderer Bedeutung. Hierfür ist die möglichst frühzeitige Kenntnis wichtig, ob die Ablation vollständig ist oder ob Teile des zu therapierenden Areals einer weiteren Intervention bedürfen. In dieser Arbeit wurde u.a. untersucht, wie die Ausdehnung des Ablationsareals direkt nach der Intervention in einem offenen 1 T MRT ersichtlich war und insbesondere ob der Randbereich der Ablationszone beurteilt werden konnte. Bei der Mikrowellenablation können mit einer einzelnen Elektrode auf Grund der Reichweite der elektromagnetischen Wellen im Gewebe nur kleinere Tumorherde therapiert werden. Diverse Studien mit der RFA haben gezeigt, dass sich das Ablationsvolumen mittels Flüssigkeitsinjektion vergrößern ließ. Ein Studienziel dieser Arbeit bestand in der Evaluation, ob Flüssigkeitsinjektionen vor der MWA mit unterschiedlichen Natrium- Ionenkonzentrationen ähnlich zu einer Vergrößerung des Ablationsareals führen konnten wie mit der RFA. Methodik: In dieser Rahmenschrift wurden zwei Originalarbeiten für die Radiofrequenzablation sowie eine Originalarbeit zur Mikrowellenablation zusammengefasst. Zuerst wurden die Arbeiten zur RFA gemeinsam vorgestellt und anschließend die Arbeit zur MWA. Ergebnisse: Für die Arbeiten der RFA zeigte sich, dass alle Systeme das Zielvolumen der 3 cm- Läsionen von 14,14 cm3 übertrafen. Die Ergebnisse für die 5 cm-Läsionen mit einem Zielvolumen von 65,45 cm3 zeigten ein gemischtes Bild: Die Systeme von Boston Scientific und Celon übertrafen das Zielvolumen, die Systeme von Radionics und AngioDynamics blieben unterhalb des Zielvolumens. Im MRT zeigten sich bei allen Läsionsgrößen und Serien kleinere Volumina als in der makroskopischen Messung. Gemittelt über alle vier RFA-Systeme und Läsionsgrößen waren etwa 60 % des Ablationsvolumens im MRT mit den untersuchten Sequenzen nicht sichtbar. In den Versuchen zur Mikrowellenablation zeigte sich kein signifikanter Unterschied zwischen den Versuchsreihen mit iso- oder hypertoner NaCl-Lösung im Vergleich zu der Versuchsreihe mit Wasser oder der Versuchsreihe ohne Flüssigkeitsinjektion. Diskussion: Im Vergleich der beiden verschiedenen Sequenzen zeigten sich sowohl für die RFA als auch die MWA größer visualisierte Ablationsvolumina mit der T1-Sequenz im Vergleich zur PD-Sequenz. Allerdings konnte mit den gewählten Sequenzen der Übergang von Transitionalzone zu gesundem Gewebe nicht abschließend beurteilt werden. Somit konnte unmittelbar nach der Intervention keine abschließende Aussage über die Vollständigkeit der Ablation allein aus der MR-Visualisierung getroffen werden. Mit den Versuchen der Mikrowellenablation zeigte sich, dass, im Gegensatz zu entsprechenden RFA- Versuchen, eine Flüssigkeitsinjektion vor der Intervention in das Gewebe, gleich welcher Natrium-Konzentration, nicht zu einer Vergrößerung des Ablationsareals führte. Zu einer Vergrößerung des Ablationsareals musste die MW-Antenne entweder repositioniert oder mit mehreren Elektroden gleichzeitig therapiert werden.Thermal ablation techniques like RFA and MWA became a therapy option for primary and secondary malignancies in organs and bones. An entire tumor ablation directly after intervention is crucial for the further course of the disease. Therefore, an image validation right after intervention should ratify whether the ablation was sufficient or further therapy is mandatory. One aim of this thesis was to evaluate if the entire thermal ablation necrosis, especially the border from ablated to healthy tissue, was visible directly after intervention in an open 1 T MRI system. For the MWA using a single antenna, only smaller necroses can be produced because of the limited range of microwaves in tissue. Several RFA-studies reported possible enlargement of necroses by installing sodium solutions into tissue previous to RFA. One aim of this thesis was to investigate whether preinterventional fluid injection before MWA might enlarge the necrosis similarly to fluid injection performing RFA. Methods: In this thesis, two original scientific articles for RFA and one original scientific article on MWA were summarized. Therefore, the articles related to RFA were presented together. Subsequently the MWA article was presented. Results: For the 3 cm ablation all tested RF systems exceeded the target volume of 14.14 cm3. For the 5 cm lesion only the Boston Scientific and the Celon system exceeded the target volume of 65.45 cm3. The Radionics and AngioDynamics system achieved smaller ablation volumes and remained below the target volume. For the MR-volumetry all volumes for every test series and lesion size were smaller than the macroscopically measured and calculated volumes. Averaged over all four RFA-systems, lesion sizes and sequences, 60 % of the necrosis zone after Intervention was not visible. For MWA no significant differences were detected between the test series including fluid preinjection of iso- or hypertonic saline solutions in comparison to the trials without preinjection or only water-injection. Discussion: After evaluation of the two MR sequences, in both RFA and MWA-trials the T1-sequence detected larger ablation-volumes than the PD-sequence. However, the border from the transitional zone to healthy tissue was not detectable by MRI with the respective sequences directly after intervention. Therefore, no accurate statement about the completeness of the thermal ablation by MR-imaging could be given. For MWA, fluid preinjection did not enlarge the necrosis in contrast to RFA, irrespective of sodium concentration in water. Therefore larger ablations volumes needed a repositioning of the MW-antenna or the simultaneous use of more than one MW-system