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| 2. |
- Forrer, Flavio, et al.
(författare)
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Treatment with 177Lu-DOTATOC of patients with relapse of neuroendocrine tumors after treatment with 90Y-DOTATOC.
- 2005
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Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - 0161-5505. ; 46:8, s. 1310-6
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Tidskriftsartikel (refereegranskat)abstract
- Therapy with [(90)Y-DOTA(0), Tyr(3)]-octreotide (DOTATOC, where DOTA = tetraazacyclododecane tetraacetic acid and TOC = D-Phe-c(Cys-Tyr-D-Trp-Lys-Thr-Cys)-Thr(ol)) is established for the treatment of metastatic neuroendocrine tumors. Nevertheless, many patients experience disease relapse, and further treatment may cause renal failure. Trials with (177)Lu-labeled somatostatin analogs showed less nephrotoxicity. We initiated a prospective study with (177)Lu-DOTATOC in patients with relapsed neuroendocrine tumors after (90)Y-DOTATOC treatment. METHODS: Twenty-seven patients, pretreated with (90)Y-DOTATOC, were included. The mean time between the last treatment with (90)Y-DOTATOC and (177)Lu-DOTATOC was 15.4 +/- 7.8 mo (SD). All patients were injected with 7,400 MBq of (177)Lu-DOTATOC. Restaging was performed after 8-12 wk. Hematotoxicity or renal toxicity of World Health Organization grade 1 or 2 was not an exclusion criterion. RESULTS: Creatinine levels increased significantly, from 66 +/- 14 micromol/L to 100 +/- 44 micromol/L (P < 0.0001), after (90)Y-DOTATOC therapy. The mean hemoglobin level dropped from 131 +/- 14 to 117 +/- 13 g/L (P < 0.0001) after (90)Y-DOTATOC therapy. (177)Lu-DOTATOC therapy was well tolerated. No serious adverse events occurred. The mean absorbed doses were 413 +/- 159 mGy for the whole body, 3.1 +/- 1.5 Gy for the kidneys, and 61 +/- 5 mGy for the red marrow. After restaging, we found a partial remission in 2 patients, a minor response in 5 patients, stable disease in 12 patients, and progressive disease in 8 patients. Mean hemoglobin and creatinine levels did not change significantly. CONCLUSION: (177)Lu-DOTATOC therapy in patients with relapse after (90)Y-DOTATOC treatment is feasible, safe, and efficacious. No serious adverse events occurred.
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| 3. |
- Giussani, Augusto, et al.
(författare)
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A Compartmental Model for Biokinetics and Dosimetry of 18F-Choline in Prostate Cancer Patients
- 2012
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X. ; 53:6, s. 985-993
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Tidskriftsartikel (refereegranskat)abstract
- PET with F-18-choline (F-18-FCH) is used in the diagnosis of prostate cancer and its recurrences. In this work, biodistribution data from a recent study conducted at Skane University Hospital Malmo were used for the development of a biokinetic and dosimetric model. Methods: The biodistribution of F-18-FCH was followed for 10 patients using PET up to 4 h after administration. Activity concentrations in blood and urine samples were also determined. A compartmental model structure was developed, and values of the model parameters were obtained for each single patient and for a reference patient using a population kinetic approach. Radiation doses to the organs were determined using computational (voxel) phantoms for the determination of the S factors. Results: The model structure consists of a central exchange compartment (blood), 2 compartments each for the liver and kidneys, 1 for spleen, 1 for urinary bladder, and 1 generic compartment accounting for the remaining material. The model can successfully describe the individual patients' data. The parameters showing the greatest interindividual variations are the blood volume (the clearance process is rapid, and early blood data are not available for several patients) and the transfer out from liver (the physical half-life of F-18 is too short to follow this long-term process with the necessary accuracy). The organs receiving the highest doses are the kidneys (reference patient, 0.079 mGy/MBq; individual values, 0.033-0.105 mGy/MBq) and the liver (reference patient, 0.062 mGy/MBq; individual values, 0.036-0.082 mGy/MBq). The dose to the urinary bladder wall of the reference patient varies between 0.017 and 0.030 mGy/MBq, depending on the assumptions on bladder voiding. Conclusion: The model gives a satisfactory description of the biodistribution of F-18-FCH and realistic estimates of the radiation dose received by the patients.
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| 5. |
- Kneifel, Stefan, et al.
(författare)
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Individual voxelwise dosimetry of targeted (90)Y-labelled substance P radiotherapy for malignant gliomas.
- 2007
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Ingår i: European journal of nuclear medicine and molecular imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 34:9, s. 1388-95
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Substance P is the main ligand of neurokinin type 1 (NK-1) receptors, which are consistently overexpressed in malignant gliomas. The peptidic vector (111)In/(90)Y-DOTAGA-substance P binds to these receptors and can be used for local treatment of brain tumours. Dosimetry for this interstitial brachytherapy has mainly been done using geometrical models; however, they often do not faithfully reproduce the in vivo biodistribution of radiopharmaceuticals, which is indispensable to correlate the deposited energy with clinical response. The aim of this study was to establish a reproducible dosimetry protocol for intratumoural radiopeptide therapy. METHODS: For test and therapeutic injections, 2 MBq of (111)In-substance P and 370-3,330 MBq of (90)Y-substance P, respectively, were applied in 12 patients with malignant gliomas. Over a period of 24 h, serial SPECT scans were performed on a dual-head SPECT camera. The scans were acquired in a double-energy window technique together with (99m)Tc-ECD in order to co-register the dose distributions with a separately acquired, contrast-enhanced CT scan. Quantitative voxelwise dose distribution maps (in Gy/GBq) were computed from these data using a mono-exponential decay approach. Pre- and post-therapeutic values were compared. RESULTS: Agreement between pre- and post-therapeutic dosimetry was very good and delivered absolute dose values in Gy per injected GBq. In all patients, the pretherapeutic test injection together with the CT overlay technique could predict the precise localisation of dose deposition in an anatomical context. CONCLUSION: This protocol allows a precise pretherapeutic computation of the expected three-dimensional dose distribution and is clearly superior to the previously used dosimetry based on planar scintigraphic images. It has become an indispensable tool for planning intratumoural radiopeptide therapy in glioma patients.
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| 6. |
- Sydoff, Marie, et al.
(författare)
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ABSOLUTE QUANTIFICATION OF ACTIVITY CONTENT FROM PET IMAGES USING THE PHILIPS GEMINI TF PET/CT SYSTEM.
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; Apr 7, s. 236-239
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Tidskriftsartikel (refereegranskat)abstract
- Positron emission tomography combined with computed tomography (PET/CT) is a quantitative technique suitable for diagnostics and uptake measurements. The quantitative results can be used for the purpose of the calculating absorbed dose to patients undergoing nuclear medicine investigations. Hence, the accuracy of the quantification of the activity content in organs or tissues is of great importance. When using a planar gamma camera and single photon emission computed tomography (SPECT) images, the activity content in organs and tumours has to be determined by the user, using the number of counts in the organs and the efficiency of the camera. However, when using a Philips Gemini TF PET/CT system, the activity concentration in a region of interest (ROI) is given by the system. The reliability of activity concentration values given by the Philips Gemini TF PET/CT system was studied using a Jaszczak phantom containing hot spheres of different sizes; the influence of the ROI size and the impact of organ size, that is the partial volume effect, was investigated with three different lesion-to-background ratios in the phantom. The use of a small ROI size (40 % of the large ROI size, which covered the entire sphere) showed a 15 % improvement in the recovery of the true activity. Small lesion sizes result in large underestimations of the activity concentration values.
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| 7. |
- Söderberg, Marcus, et al.
(författare)
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Evaluation of image reconstruction methods for 123I-MIBG-SPECT: a rank-order study.
- 2012
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 53:7, s. 778-784
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is an opportunity to improve the image quality and lesion detectability in single photon emission computed tomography (SPECT) by choosing an appropriate reconstruction method and optimal parameters for the reconstruction. Purpose: To optimize the use of the Flash 3D reconstruction algorithm in terms of equivalent iteration (EI) number (number of subsets times the number of iterations) and to compare with two recently developed reconstruction algorithms ReSPECT and orthogonal polynomial expansion on disc (OPED) for application on (123)I-metaiodobenzylguanidine (MIBG)-SPECT. Material and Methods: Eleven adult patients underwent SPECT 4 h and 14 patients 24 h after injection of approximately 200 MBq (123)I-MIBG using a Siemens Symbia T6 SPECT/CT. Images were reconstructed from raw data using the Flash 3D algorithm at eight different EI numbers. The images were ranked by three experienced nuclear medicine physicians according to their overall impression of the image quality. The obtained optimal images were then compared in one further visual comparison with images reconstructed using the ReSPECT and OPED algorithms.ResultsThe optimal EI number for Flash 3D was determined to be 32 for acquisition 4 h and 24 h after injection. The average rank order (best first) for the different reconstructions for acquisition after 4 h was: Flash 3D(32) > ReSPECT > Flash 3D(64) > OPED, and after 24 h: Flash 3D(16) > ReSPECT > Flash 3D(32) > OPED. A fair level of inter-observer agreement concerning optimal EI number and reconstruction algorithm was obtained, which may be explained by the different individual preferences of what is appropriate image quality. Conclusion: Using Siemens Symbia T6 SPECT/CT and specified acquisition parameters, Flash 3D(32) (4 h) and Flash 3D(16) (24 h), followed by ReSPECT, were assessed to be the preferable reconstruction algorithms in visual assessment of (123)I-MIBG images.
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| 8. |
- Tavola, Federico, et al.
(författare)
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Nonlinear compartmental model of F-18-choline
- 2012
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Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 1872-9614 .- 0969-8051. ; 39:2, s. 261-268
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: This work develops a compartmental model of F-18-choline in order to evaluate its biokinetics and so to describe the temporal variation of the radiopharmaceuticals' uptake in and clearance from organs and tissues. Methods: Ten patients were considered in this study. A commercially available tool for compartmental analysis (SAAM II) was used to model the values of activity concentrations in organs and tissues obtained from PET images or from measurements of collected blood and urine samples. Results: A linear compartmental model of the biokinetics of the radiopharmaceutical was initially developed. It features a central compartment (blood) exchanging with organs. The structure describes explicitly liver, kidneys, spleen, blood and urinary excretion. The linear model tended to overestimate systematically the activity in the liver and in the kidney compartments in the first 20 min post-administration. A nonlinear process of kinetic saturation was considered, according to the typical Michaelis-Menten kinetics. Therefore nonlinear equations were added to describe the flux of 18F-choline from blood to liver and from blood to kidneys. The nonlinear model showed a tendency for improvement in the description of the activity in liver and kidneys, but not for the urine. Conclusions: The simple linear model presented is not able to properly describe the biokinetics of 18F-choline as measured in prostatic cancer patients. The introduction of nonlinear kinetics, although based on physiologically plausible assumptions, resulted in nonsignificant improvements of the model predictive power. (C) 2012 Elsevier Inc. All rights reserved.
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| 9. |
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| 10. |
- Uusijärvi, Helena, et al.
(författare)
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Biokinetics Of 18F-Choline Studied In Four Prostate Cancer Patients
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 240-244
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Tidskriftsartikel (refereegranskat)abstract
- Biokinetic data are important when calculating the absorbed dose to the patients and can also be used to find the optimal time between injection and imaging. To the authors' knowledge, there are no published biokinetic data in humans for (18)F-choline, except some distribution data at single time points. Four patients with suspicion of metastases due to biochemical recurrence (measurable prostate-specific antigen in plasma) after radical prostatectomy were injected with (18)F-choline. Four whole-body PET/CT images were taken with 1 h interval, starting immediately after injection. Blood samples were taken and all urine was collected for 3.5 h. The corrected decay activity content in the kidneys was 22-37 % higher immediately after injection when compared with the later time points. The highest activity concentration was found in kidneys (43 kBq ml(-1)). The organ with highest activity content was the liver (11 % of injected activity, % IA). Thirty minutes after the injection 4-16 % IA was left in the blood. Less than 9 % IA was excreted with the urine during the first 3.5 h after injection.
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