| 1. |
- Andersson, JLR, et al.
(författare)
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A multivariate approach to registration of dissimilar tomographic images
- 1999
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Ingår i: European Journal of Nuclear Medicine. - : SPRINGER VERLAG. - 0340-6997 .- 1432-105X .- 1619-7070 .- 1619-7089. ; 26:7, s. 718-733
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Tidskriftsartikel (refereegranskat)abstract
- We devised a method to allow for retrospective registration of tomographic images with very different information content, the main emphasis being on sets of positron emission tomography images obtained with different tracers. A multivariate cost-function
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| 2. |
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| 3. |
- Ribom, Dan, et al.
(författare)
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Potential significance of 11C-methionine PET as a marker for the radiosensitivity of low-grade gliomas
- 2002
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Ingår i: European Journal of Nuclear Medicine. - : Springer Science and Business Media LLC. - 0340-6997 .- 1432-105X .- 1619-7070 .- 1619-7089. ; 29:5, s. 632-640
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Tidskriftsartikel (refereegranskat)abstract
- The role for radiotherapy in patients with low-grade gliomas remains controversial. Two large prospective studies have failed to demonstrate a radiotherapeutic dose-response effect, and EORTC trial 22845 found no difference in survival between patients receiving adjuvant radiotherapy and those who received radiotherapy at tumour progression. The aim of this retrospective study was to analyse the patterns of carbon-11 methionine (MET) uptake on positron emission tomography (PET) in tumours treated with immediate radiotherapy and in those treated with delayed radiotherapy at the time of tumour progression. The 21 adult patients studied had histologically confirmed low-grade gliomas and had undergone a pre-treatment PET scan and a follow-up PET scan at the time of progression. Eleven of the patients had undergone initial radiotherapy a median of 5 weeks after the surgical procedure. The median time to progression was 3.5 years for this group, compared with 1.6 years for the group with delayed radiotherapy ( P=0.06). At the time of progression, non-irradiated tumours had a significantly higher MET uptake ( P=0.02) and a larger uptake volume ( P=0.008) compared with baseline, whereas irradiated tumours showed no statistically significant change. We observed a correlation between high pre-treatment uptake of MET and reduction in MET uptake in response to radiotherapy ( P=0.008). All irradiated tumours recurred within the radiation field. In conclusion, our results demonstrate signs of a residual radiation effect at the time of tumour progression in low-grade gliomas with high pre-treatment uptake of MET. Pre-treatment methionine uptake may be a marker for the radiosensitivity of low-grade gliomas.
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| 4. |
- Sundberg, Åsa Liljegren, et al.
(författare)
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Treatment of cultured glioma cells with EGFR-TKI gefitinib (‘Iressa’, ZD1839) increases the uptake of astatinated EGF despite absence of gefitinib-mediated growth inhibition
- 2003
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Ingår i: European Journal of Nuclear Medicine. - : Springer Science and Business Media LLC. - 0340-6997 .- 1432-105X .- 1619-7070 .- 1619-7089. ; 30:5, s. 727-9
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Tidskriftsartikel (refereegranskat)abstract
- The EGFR-TKI (epidermal growth factor receptor tyrosine kinase inhibitor) gefitinib ("Iressa", ZD1839), a reversible growth inhibitor of EGFR-expressing tumour cells, has been shown to enhance the antitumour effect of ionising radiation, and also to increase the uptake of radioiodinated EGF. Thus, combination of gefitinib treatment and radionuclide targeting is an interesting option for therapy of brain tumours that are difficult to treat with conventional methods. The aim of this study was to evaluate how pre-treatment with gefitinib affects binding of astatinated EGF ((211)At-EGF) to cultured glioma U343 cells, which express high levels of EGFR. The growth of U343 cells in the presence of gefitinib was investigated, and it was found that gefitinib does not significantly inhibit the growth of these cells. Nevertheless, the uptake of (211)At-EGF in U343 cells was markedly increased (up to 3.5 times) in cells pre-treated with gefitinib (1 microM). This indicates that a combination of gefitinib treatment and radionuclide targeting to EGFR might be a useful therapeutic modality, even for patients who do not respond to treatment with gefitinib alone.
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| 5. |
- Xu, Jiahua, et al.
(författare)
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Quantitative analysis of inhomogeneity in ventilation SPET
- 2001
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Ingår i: European Journal of Nuclear Medicine. - : Springer. - 0340-6997 .- 1432-105X .- 1619-7070 .- 1619-7089. ; 28:12, s. 1795-1800
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate a method for quantification of inhomogeneity in ventilation single-photon emission tomography (SPET). Nine emphysematous patients, nine life-long non-smokers and nine smokers were included in the study. The SPET investigation was performed after 50 MBq (99m)Tc-Technegas had been inhaled by each subject in the supine position. A single-head gamma camera, equipped with a general-purpose parallel-hole collimator using 64 projections (20 s each) over 360 degrees, was used. Data were acquired in 128x128 matrices. Attenuation correction was applied based upon computed tomography (CT) density maps. Lung regions of interest were delineated manually on CT images and then positioned on SPET images. Several attenuation-corrected transaxial SPET slices (thickness 1 cm, spacing 3.5 cm) were reconstructed. Each SPET slice was divided into several 2x2x1 cm(3) elements. Inhomogeneity was assessed by the coefficient of variation (CV) of the pixel counts within these elements (micro-level) and the CV of the total counts of the elements (macro-level). Micro-level CVs in non-smokers varied between 1% and 41%, whereas they were dispersed over a wide range (1%-600%) in emphysematous patients. In seven smokers, the frequency distribution of micro-level CVs was within the normal range, whereas in the other two smokers the values were between the normal range and the range in emphysematous patients. The pooled mean values of micro-level CVs and macro-level CVs in each subject clearly separated the patients from the others. Parametric images of micro-level CV indicated the localisation and severity of ventilation inhomogeneity. We conclude that the present method enables quantification and localisation of regional inhomogeneity in ventilation SPET images.
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| 6. |
- Benjegård, S A, et al.
(författare)
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Intraoperative tumour detection using 111In-DTPA-D-Phe1-octreotide and a scintillation detector.
- 2001
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Ingår i: European journal of nuclear medicine. - : Springer Science and Business Media LLC. - 0340-6997 .- 1619-7070 .- 1619-7089. ; 28:10, s. 1456-62
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Tidskriftsartikel (refereegranskat)abstract
- Intraoperative tumour detection has been used in many applications. The examined tumour forms have varied and different detector systems and radiopharmaceuticals have also been used. The aim of this study was to evaluate and compare the ability of an NaI(T1) scintillation detector to detect primary tumours and metastases in patients with different endocrine tumour types (e.g. carcinoid tumours, endocrine pancreatic tumours and thyroid tumours) and in patients with breast carcinoma or benign thyroid lesions, on the basis of their somatostatin receptor expression after i.v. injection of 111In-DTPA-D-Phe1-octreotide. Thirty patients were injected with 111In-DTPA-D-Phe1-octreotide intravenously. Scintigraphic images were taken 1 day after injection of the radiopharmaceutical, and surgery was performed 1-7 days post injection. An NaI(T1) scintillation detector was used for intraoperative tumour detection. Tissue samples were collected during surgery for determination of 111In activity concentration and histopathological examination. The scintigraphic images were positive in 29 out of 30 patients. Intraoperative tumour detection was successful in 43 of 66 collected biopsies: 10 out of 11 for carcinoid tumours, 7 out of 10 for medullary thyroid carcinoma (MTC) and 14 out of 22 for breast cancer. On the basis of our findings we conclude that intraoperative tumour detection with 111In-DTPA-D-Phe1-octreotide using this NaI(T1) detector can be successful especially for carcinoid tumours and endocrine pancreatic tumours, due to the relatively high activity concentrations in these tumour types, but is less successful in other forms of thyroid cancer, including MTC, and breast cancer. For successful intraoperative detection, the detector characteristics are also very important, and further improvement of the detector systems is required to increase the sensitivity and specificity.
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| 7. |
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| 8. |
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| 9. |
- Dewaraja, Yuni K., et al.
(författare)
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Monte Carlo evaluation of object shape effects in iodine-131 SPET tumor activity quantification
- 2001
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Ingår i: European Journal Of Nuclear Medicine. - : Springer Science and Business Media LLC. - 1432-105X .- 0340-6997 .- 1619-7089. ; 28:7, s. 900-906
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Tidskriftsartikel (refereegranskat)abstract
- In our clinical iodine-131 single-photon emission tomography (SPET) quantification for radioimmunotherapy, calibration and partial volume correction are based on measurements with phantoms containing spheres to simulate patient tumors even though real tumors are frequently nonspherical. In this study, Monte Carlo simulation was used to evaluate how object shape influences "spill-out" and "spill-in", which are major sources of quantification error associated with the poor spatial resolution of 131I SPET. Objects that varied in shape (spheres, cylinders, and an irregular structure) but were identical in activity and volume were simulated. Iterative reconstruction employed both attenuation and triple-energy-window scatter compensation. VOIs were defined in the reconstructed images both using physical boundaries and using expanded boundaries to allow for the limited resolution. When physical boundaries were used, both spill-out and spill-in were more significant for nonspherical structures than for spherical structures. Over the range of object volumes (50-200 ml) and at all background levels, VOI counts in cylinders were lower than VOI counts in spheres. This underestimation increased with decrease in object size (for the cold background -18% at 200 ml and -39% at 50 ml). It also decreased with increase in background activity because spill-in partially compensated for spill-out. It was shown that with a VOI larger than physical size, the results are independent of object shape and size only in the case of cold background. Activity quantification was carried out using a procedure similar to that used in our clinic. Quantification of nonspherical objects was improved by simple sphere-based partial volume correction, but the error was still large in some cases (for example, -39% for a 50-ml cylinder in a cold background and -35% for a 200-ml irregular structure defined on the basis of a typical tumor outlined on an X-ray computed tomography scan of a patient with non-Hodgkin's lymphoma). Partial volume correction by patient-specific Monte Carlo simulation may provide better quantification accuracy.
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| 10. |
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