| 1. |
- Edwards, David, et al.
(författare)
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99mTc-NC100668, an agent for imaging venous thromboembolism : The effect of anticoagulant or thrombolytic therapy on the uptake and retention of radioactivity in blood clots in vivo
- 2007
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Ingår i: Nuclear medicine communications. - : Ovid Technologies (Wolters Kluwer Health). - 0143-3636 .- 1473-5628. ; 28:1, s. 55-62
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The purpose of this study was to evaluate the uptake of Tc-NC100668 into blood clots and elucidate the potential for medications commonly used to treat thromboembolism to interfere with the uptake and retention of Tc-NC100668. METHODS: Tc-NC100668 in vivo uptake and retention in a range of blood clot of various ages (up to 4 h old) and in the presence of anticoagulants or thrombolytic therapies was measured in a rat model of deep vein thrombosis. RESULTS: Tc-NC100668 was rapidly absorbed into and retained by blood clots and was not significantly affected by the presence of unfractionated or low molecular weight heparin or thrombin inhibitor. Tissue plasminogen activator reduced the uptake of Tc-NC100668 into blood clot by a factor of 3 when adjusted to allow for changes in the weight of the blood clot. CONCLUSIONS: This study has demonstrated that the uptake and retention of Tc-NC100668 into blood clots in the rat model of deep vein thrombosis is rapid and maintained over at least a 4 h post-injection period. It has been shown that Tc-NC100668 is retained in blood clots even in the presence of therapeutic doses of those anticoagulant and thrombolytic therapies typically used to treat pulmonary embolism and venous thrombosis.
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| 4. |
- Gref, Margareta, 1950-, et al.
(författare)
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99mTc-diethylenetriamine penta-acetate plasma clearance in advanced renal failure by the mean sojourn time approach
- 2009
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 30:3, s. 202-205
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The single-sample 99mTc-diethylenetriamine penta-acetate (DTPA) clearance method by Christensen and Groth is recommended by the Radionuclides in Nephrourology Committee on Renal Clearance for use in adults with an estimated glomerular filtration rate (GFR) ≥30 ml/min. The purpose of this study was to test a new 99mTc-DTPA single-sample low clearance formula for GFR lesser than 30 ml/min. Methods: Twenty-one adult patients (29 investigations) were included. Reference clearance was calculated with both 51Cr-EDTA and 99mTc-DTPA according to Brøchner-Mortensen with samples drawn between 3 and 24 h. Single-sample clearance was calculated from a 24 h sample using the low clearance formula Equation (Uncited)Image Tools C(t) is the activity of the tracer in the plasma sample t minutes after the injection and Q0 is the injected amount. ECV is the extracellular volume in ml defined as the distribution volume of the tracer. ECV is estimated from the body surface area as ECV=8116.6×body surface area-28.2. Results: The mean difference between reference and 99mTc-DTPA single-sample clearance was -0.5 ml/min (SD 1.0 ml/min) for 99mTc-DTPA and -0.8 ml/min (SD 1.2 ml/min) for 51Cr-EDTA as reference clearance. Conclusion: In adult patients it is possible, even with GFR lesser than 30 ml/min, to get an accurate determination of 99mTc-DTPA plasma clearance from a single sample using the mean sojourn time approach. The blood sample should be obtained about 24 h after injection of the GFR tracer.
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| 5. |
- Gutte, Henrik, et al.
(författare)
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Automated interpretation of PET/CT images in patients with lung cancer.
- 2007
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 28:2, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To develop a completely automated method based on image processing techniques and artificial neural networks for the interpretation of combined [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) images for the diagnosis and staging of lung cancer. Methods: A total of 87 patients who underwent PET/CT examinations due to suspected lung cancer comprised the training group. The test group consisted of PET/CT images from 49 patients suspected with lung cancer. The consensus interpretations by two experienced physicians were used as the 'gold standard' image interpretation. The training group was used in the development of the automated method. The image processing techniques included algorithms for segmentation of the lungs based on the CT images and detection of lesions in the PET images. Lung boundaries from the CT images were used for localization of lesions in the PET images in the feature extraction process. Eight features from each examination were used as inputs to artificial neural networks trained to classify the images. Thereafter, the performance of the network was evaluated in the test set. Results: The performance of the automated method measured as the area under the receiver operating characteristic curve, was 0.97 in the test group, with an accuracy of 92%. The sensitivity was 86% at a specificity of 100%. Conclusions: A completely automated method using artificial neural networks can be used to detect lung cancer with such a high accuracy that the application as a clinical decision support tool appears to have significant potential.
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| 6. |
- Jögi, Jonas, et al.
(författare)
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Heart failure diagnostics based on ventilation/perfusion single photon emission computed tomography pattern and quantitative perfusion gradients.
- 2008
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 29:8, s. 666-673
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Left heart failure (LHF) is a common and frequently overlooked condition owing to insufficient diagnostic methods. This can potentially delay onset of treatment. Our clinical experience with ventilation/perfusion single photon emission computed tomography (V/P SPECT) indicates that perfusion shows an antigravitational distribution pattern in LHF. The aim of the study was to test the hypothesis that LHF diagnosis can be made on the basis of V/P SPECT, and to develop and perform a first evaluation of objective parameters for LHF diagnostics in terms of perfusion gradients. METHODS: This retrospective study included 247 consecutive patients with clinical suspicion of pulmonary embolism (PE), who were examined with V/P SPECT. Perfusion gradients were developed and quantified in dorso-ventral and cranio-caudal directions. Quantitative results were compared with visual interpretation of patients with normal and heart failure patterns. Patients with LHF pattern were retrospectively followed up by review of medical records to confirm or discard heart failure diagnosis at the time of V/P SPECT examination. RESULTS: LHF pattern on V/P SPECT was identified in 36 patients (15%), normal ventilation/perfusion pattern was found in 67 patients (27%), and PE in 62 patients (25%). The follow-up confirmed heart failure diagnosis in 32 of the 36 cases with LHF pattern, leading to a positive predictive value of 88% for LHF diagnosis based on V/P SPECT. Dorso-ventral perfusion gradients discriminated normal from LHF patients. CONCLUSION: In patients with suspected PE, LHF is common. Appropriate V/P SPECT pattern recognition, supported by objectively determined dorso-ventral perfusion gradients, allows the diagnosis of LHF. A positive perfusion gradient in the dorso-ventral direction should lead to consideration of heart failure as a possible explanation for the symptoms in these patients.
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| 7. |
- Lyrdal, David, 1965, et al.
(författare)
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Evaluation of sorafenib treatment in metastatic renal cell carcinoma with 2-fluoro-2-deoxyglucose positron emission tomography and computed tomography.
- 2009
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Ingår i: Nuclear medicine communications. - 1473-5628. ; 30:7, s. 519-24
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: New potent tyrosine kinase inhibitors such as sorafenib are the most effective treatment for metastatic renal cell carcinoma (MRCC) today. In this study, we used [18F]-2-fluoro-2-deoxyglucose (FDG) with positron emission tomography (PET) combined with computed tomography (CT) to evaluate early effects of sorafenib in patients with MRCC. METHODS: Ten patients, eight males and two females, with a mean age of 61 years (49-72 years), with MRCC were enrolled. A total of 52 lesions, two to nine lesions/patient, out of which 39 were soft lesions, were evaluated. The [18F]FDG-PET/CT was performed before treatment and after 1-2 months. A region of interest (ROI) was identified including the lesions where the glucose uptake was measured, calculating the average value within the ROI and using the cerebellum as the reference. The same ROI was measured in the subsequent FDG-PET. The sum of the diameters was measured in CT according to the Response Evaluation Criteria in Solid Tumors (RECIST). Sorafenib was given 400 mg twice daily orally. RESULTS: After 1-2 months, the mean glucose uptake in all lesions decreased to 75% (32-105%) of initial values of ROI as measured by FDG-PET. The mean glucose uptake in soft lesions decreased to 71% (32-108%) and in skeletal lesions to 82% (53-101%). The sum of the diameters measured by CT decreased to 80% (57-94%) of the initial value in soft lesions according to the RECIST. CONCLUSION: An early decrease in the mean glucose uptake was found in both soft and skeletal lesions after treatment with sorafenib. FDG-PET thus seems to be advantageous, compared with RECIST evaluation, which is limited to soft lesions.
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| 8. |
- Norberg, Pernilla, 1970-, et al.
(författare)
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Evaluation of reconstruction techniques for lung single photon emission tomography: a Monte Carlo study.
- 2007
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Ingår i: Nuclear medicine communications. - United States : Lippincott Williams & Wilkins. - 0143-3636 .- 1473-5628. ; 28:12, s. 929-36
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In studies of the distribution of lung function, the image quality of lung single photon emission computed tomography (SPECT) is important and one factor influencing it is the reconstruction algorithm. AIM: To systematically evaluate ordered subsets expectation maximization (OSEM) and compare it with filtered back-projection (FBP) for lung SPECT with Tc. METHODS: The evaluation of the number of iterations used in OSEM was based on the image quality parameter contrast. The comparison between OSEM and FBP was based on trade-off plots between statistical noise and spatial resolution for different filter parameters, collimators and count-levels. A Monte Carlo technique was used to simulate SPECT studies of a digital thorax phantom containing two sets of activity: one with a homogeneous activity distribution within the lungs and the other with superposed high- and low-activity objects. Statistical noise in the reconstructed images was calculated as the coefficient of variation (CV) and spatial resolution as full width at half-maximum (FWHM). RESULTS: For the configuration studied, the OSEM reconstruction in combination with post-filtering should be used in lung SPECT studies with at least 60 MLEM equivalent iterations. Compared to FBP the spatial resolution was improved by about 1 mm. For a constant level of CV, a four-fold increase in count level resulted in an increased resolution of about 2 mm. Spatial resolution and cut-off frequency depends on what value of noise in the image is acceptable also increased by using a low-energy, high-resolution collimator for CV values above 3%. The choice of noise-reducing filter and cut-off frequency depends on what value of noise in the image is acceptable.
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| 9. |
- Olsson, Anna, 1974-, et al.
(författare)
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Evaluation of reconstruction techniques in regional cerebral blood flow SPECT using trade-off plots : A Monte Carlo study
- 2007
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Ingår i: Nuclear medicine communications. - United States : Lippincott Williams & Wilkins. - 0143-3636 .- 1473-5628. ; 28:9, s. 719-725
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIM: The image quality of single photon emission computed tomography (SPECT) depends on the reconstruction algorithm used. The purpose of the present study was to evaluate parameters in ordered subset expectation maximization (OSEM) and to compare systematically with filtered back-projection (FBP) for reconstruction of regional cerebral blood flow (rCBF) SPECT, incorporating attenuation and scatter correction. METHODS: The evaluation was based on the trade-off between contrast recovery and statistical noise using different sizes of subsets, number of iterations and filter parameters. Monte Carlo simulated SPECT studies of a digital human brain phantom were used. The contrast recovery was calculated as measured contrast divided by true contrast. Statistical noise in the reconstructed images was calculated as the coefficient of variation in pixel values. RESULTS: A constant contrast level was reached above 195 equivalent maximum likelihood expectation maximization iterations. The choice of subset size was not crucial as long as there were > or = 2 projections per subset. The OSEM reconstruction was found to give 5-14% higher contrast recovery than FBP for all clinically relevant noise levels in rCBF SPECT. The Butterworth filter, power 6, achieved the highest stable contrast recovery level at all clinically relevant noise levels. The cut-off frequency should be chosen according to the noise level accepted in the image. CONCLUSION: Trade-off plots are shown to be a practical way of deciding the number of iterations and subset size for the OSEM reconstruction and can be used for other examination types in nuclear medicine.
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