38 research outputs found
Production of the Auger emitter Sb-119 for targeted radionuclide therapy using a small PET-cyclotron
No full textProduction and dosimetric aspects of the potent Auger emitter 58mCo for targeted radionuclide therapy of small tumours
No full textMedium to large scale radioisotope production for targeted radiotherapy using a small PET cyclotron
No full textIn recent years the use of radionuclides in targeted cancer therapy has increased. In this study we have developed a high-current solid target system and demonstrated that by the use of a typical low-energy medical cyclotron, it is possible to produce tens of GBq's of many unconventional radionuclides relevant for cancer therapy such as 64Cu and 119Sb locally at the hospitals
Production and dosimetric aspects of the potent Auger emitter Co-58m for targeted radionuclide therapy of small tumours
No full textBased on theoretical calculations, the Auger emitter 58mCo has been identified as a potent nuclide for targeted radionuclide therapy of small tumors. During the production of this isotope, the coproduction of the long-lived ground state 58gCo is unfortunately unavoidable, as is ingrowth of the ground state following the isomeric decay of 58mCo. The impact of 58gCo as a bþ- and c-emitting impurity should be included in the dosimetric analysis. The purpose of this study was to investigate this critical part of dosimetry based on experimentally determined production yields of 58mCo and 58gCo using a low-energy cyclotron. Also, the cellular S-values for 58mCo have been calculated and are presented here for the first time
Preparation and Evaluation of [18F]AlF-NOTA-NOC for PET Imaging of Neuroendocrine Tumors: Comparison to [68Ga]Ga-DOTA/NOTA-NOC
No full textBackground: The somatostatin receptors 1–5 are overexpressed on neuroendocrine neoplasms and, as such, represent a favorable target for molecular imaging. This study investigates the potential of [18F]AlF-NOTA-[1-Nal3]-Octreotide and compares it in vivo to DOTA- and NOTA-[1-Nal3]-Octreotide radiolabeled with gallium-68. Methods: DOTA- and NOTA-NOC were radiolabeled with gallium-68 and NOTA-NOC with [18F]AlF. Biodistributions of the three radioligands were evaluated in AR42J xenografted mice at 1 h p.i and for [18F]AlF at 3 h p.i. Preclinical PET/CT was applied to confirm the general uptake pattern. Results: Gallium-68 was incorporated into DOTA- and NOTA-NOC in yields and radiochemical purities greater than 96.5%. NOTA-NOC was radiolabeled with [18F]AlF in yields of 38 ± 8% and radiochemical purity above 99% after purification. The biodistribution in tumor-bearing mice showed a high uptake in tumors of 26.4 ± 10.8 %ID/g for [68Ga]Ga-DOTA-NOC and 25.7 ± 5.8 %ID/g for [68Ga]Ga-NOTA-NOC. Additionally, [18F]AlF-NOTA-NOC exhibited a tumor uptake of 37.3 ± 10.5 %ID/g for [18F]AlF-NOTA-NOC, which further increased to 42.1 ± 5.3 %ID/g at 3 h p.i. Conclusions: The high tumor uptake of all radioligands was observed. However, [18F]AlF-NOTA-NOC surpassed the other clinically well-established radiotracers in vivo, especially at 3 h p.i. The tumor-to-blood and -liver ratios increased significantly over three hours for [18F]AlF-NOTA-NOC, making it possible to detect liver metastases. Therefore, [18F]AlF demonstrates promise as a surrogate pseudo-radiometal to gallium-68
Preclinical Evaluation of the Copper-64 Labeled GRPR-Antagonist RM26 in Comparison with the Cobalt-55 Labeled Counterpart for PET-Imaging of Prostate Cancer
No full textGastrin-releasing peptide receptor (GRPR) is overexpressed in the majority of prostate cancers. This study aimed to investigate the potential of 64Cu (radionuclide for late time-point PET-imaging) for imaging of GRPR expression using NOTA-PEG2-RM26 and NODAGA-PEG2-RM26. Methods: NOTA/NODAGA-PEG2-RM26 were labeled with 64Cu and evaluated in GRPR-expressing PC-3 cells. Biodistribution of [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 was studied in PC-3 xenografted mice and compared to the biodistribution of [57Co]Co-NOTA/NODAGA-PEG2-RM26 at 3 and 24 h p.i. Preclinical PET/CT imaging was performed in tumor-bearing mice. NOTA/NODAGA-PEG2-RM26 were stably labeled with 64Cu with quantitative yields. In vitro, binding of [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 was rapid and GRPR-specific with slow internalization. In vivo, [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 bound specifically to GRPR-expressing tumors with fast clearance from blood and normal organs and displayed generally comparable biodistribution profiles to [57Co]Co-NOTA/NODAGA-PEG2-RM26; tumor uptake exceeded normal tissue uptake 3 h p.i.. Tumor-to-organ ratios did not increase significantly with time. [64Cu]Cu-NOTA-PEG2-RM26 had a significantly higher liver and pancreas uptake compared to other agents. 57Co-labeled radioconjugates showed overall higher tumor-to-non-tumor ratios, compared to the 64Cu-labeled counterparts. [64Cu]Cu-NOTA/NODAGA-PEG2-RM26 was able to visualize GRPR-expression in a murine PC model using PET. However, [55/57Co]Co-NOTA/NODAGA-PEG2-RM26 provided better in vivo stability and overall higher tumor-to-non-tumor ratios compared with the 64Cu-labeled conjugates.De två första författarna delar förstaförfattarskapetDe två sista författarna delar sistaförfattarskapet</p
In Vivo Evaluation of a Bombesin Analogue Labeled with Ga-68 and Co-55/57
No full textPurpose: The purpose of this study was to apply an analogue of bombesin, NOTA-AMBA, labeled with Co-55 or Ga-68, for preclinical imaging of prostate cancer. Procedures: The peptide NOTA-AMBA was labeled with Ga-68 or Co-55 by microwave irradiation. Biodistribution in xenograft mice (PC3) was performed at 1, 4, and 24 h (only cobalt at 24 h) using a fixed amount of peptide. Four weeks post-inoculation, xenograft mice were positron emission tomography/X-ray computed tomography scanned after tail vein injection of [ 68Ga]NOTA-AMBA or [ 55Co]NOTA-AMBA. Results: Labeling with Ga-68 and Co-55/57 was achieved in yields greater than 90 %. A radiochemical purity (RCP) of 95 and 90 % were obtained for Ga-68 and Co-55, respectively. Both radiopeptides showed high uptake in the intestines, stomach, pancreas, and in the tumor ([ 68Ga]NOTA-AMBA, 10.3 %ID/g at 1 h to 6.4 %ID/g at 4 h; [ 57Co]NOTA-AMBA, 8.2 %ID/g at 1 h to 5.3%ID/g at 24 h). Normal tissue cleared over time improving tumor-to-background ratios. Conclusions: NOTA-AMBA was labeled in high yields and RCP with Ga-68 and Co-55/57. High tumor uptake in a subcutaneous mouse prostate cancer model was observed. At 24 h, [ 55/57Co]NOTA-AMBA showed better tumor-to-organ ratios than [ 68Ga]NOTA-AMBA at both 1 and 4 h post-injection. Hence, for imaging, [ 55Co]NOTA-AMBA was found to be superior compared to [ 68Ga]NOTA-AMBA. </p
Improving contrast and detectability - imaging with [55Co]Co-DOTATATE in comparison with [64Cu]Cu-DOTATATE and [68Ga]Ga-DOTATATE
No full textPET imaging at late time points after injection may allow tracer clearance from normal tissue and hence improve image contrast and detectability. 55Co is a promising isotope with high positron yield and a long half-life suitable for imaging at delayed time points. Here, we compared the 3 radioconjugates [68Ga]Ga-DOTATATE, [64Cu]Cu-DOTATATE, and [55Co]Co-DOTATATE by PET/CT imaging in NOD-SCID mice bearing subcutaneous somatostatin receptor-expressing AR42J tumors. Methods:55Co and 64Cu were produced by the 54Fe(d,n)55Co and 64Ni(p,n)64Cu nuclear reactions, whereas 68Ga was obtained from a 68Ge/68Ga generator. 55Co and 64Cu were labeled with DOTATATE by heating in a sodium acetate buffer and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer, respectively. AR42J tumor-bearing mice were dynamically scanned 0-1 h after injection. For 64Cu and 55Co, additional imaging was also performed at late time points after 4 and 24 h. Dose calculations were based on a known biodistribution. The cumulated disintegrations in each organ were calculated by integration of a fitted exponential function to the biodistribution of each respective organ. Equivalent doses were calculated by OLINDA/EXM using the MIRD formalism. Results: Tumor uptake was rapid from 0 to 1 h after injection for all 3 radioconjugates. Normal-tissue ratios as represented by tumor-to-liver, tumor-to-kidney, and tumor-to-muscle ratios increased significantly over time, with [55Co]Co-DOTATATE reaching the highest ratio of all radioconjugates. For [55Co]Co-DOTATATE, the tumor-to-liver ratio increased to 65 ± 16 at 4 h and 50 ± 6 at 24 h, which were 15 (P < 0.001) and 30 (P < 0.001) times higher, respectively, than the corresponding ratios for [64Cu]Cu-DOTATATE and 5 (P < 0.001) times higher than that of [68Ga]Ga-DOTATATE at 1 h. Correspondingly, tumor-to-kidney and tumor-to-muscle ratios for [55Co]Co-DOTATATE were 4 (P < 0.001) and 11 (P < 0.001) times higher than that of [64Cu]Cu-DOTATATE at 24 h. An equivalent dose was calculated as 9.6E-02 mSv/MBq for [55Co]Co-DOTATATE. Conclusion: [55Co]Co-DOTATATE demonstrated superior image contrast compared with [64Cu]Cu-DOTATATE and [68Ga]Ga-DOTATATE for PET imaging of somatostatin receptor-expressing tumors, warranting translation into clinical trials. Dosimetry calculations found that effective doses for [55Co]Co-DOTATATE were comparable to those for both [64Cu]Cu-DOTATATE and [68Ga]Ga-DOTATATE.</p
High Contrast PET Imaging of GRPR Expression in Prostate Cancer Using Cobalt-Labeled Bombesin Antagonist RM26
No full textHigh gastrin releasing peptide receptor (GRPR) expression is associated with numerous cancers including prostate and breast cancer. The aim of the current study was to develop a Co-55-labeled PET agent based on GRPR antagonist RM26 for visualization of GRPR-expressing tumors. Labeling with Co-57 and Co-55, stability, binding specificity, and in vitro and in vivo characteristics of Co-57-NOTA-PEG(2)-RM26 were studied. NOTA-PEG(2)-RM26 was successfully radiolabeled with Co-57 and Co-55 with high yields and demonstrated high stability. The radiopeptide showed retained binding specificity to GRPR in vitro and in vivo. Co-57-NOTA-PEG(2)-RM26 biodistribution in mice was characterized by rapid clearance of radioactivity from blood and normal non-GRPR-expressing organs and low hepatic uptake. The clearance was predominantly renal with a low degree of radioactivity reabsorption. Tumor-to-blood ratios were approximately 200 (3 h pi) and 1000 (24 h pi). The favorable biodistribution of cobalt-labeled NOTA-PEG(2)-RM26 translated into high contrast preclinical PET/CT (using Co-55) and SPECT/CT (using Co-57) images of PC-3 xenografts. The initial biological results suggest that Co-55-NOTA-PEG(2)-RM26 is a promising tracer for PET visualization of GRPR-expressing tumors
