| 1. |
- af Bjerkén, Sara, et al.
(författare)
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Reliability and validity of visual analysis of [18F]FE-PE2I PET/CT in early Parkinsonian disease
- 2023
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Ingår i: Nuclear medicine communications. - : Wolters Kluwer. - 0143-3636 .- 1473-5628. ; 44:5, s. 397-406
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Tidskriftsartikel (refereegranskat)abstract
- Objective: [18F]FE-PE2I (FE-PE2I) is a new radiotracer for dopamine transporter (DAT) imaging with PET. The aim of this study was to evaluate the visual interpretation of FE-PE2I images for the diagnosis of idiopathic Parkinsonian syndrome (IPS). The inter-rater variability, sensitivity, specificity, and diagnostic accuracy for visual interpretation of striatal FE-PE2I compared to [123I]FP-CIT (FP-CIT) single-photon emission computed tomography (SPECT) was evaluated.Methods: Thirty patients with newly onset parkinsonism and 32 healthy controls with both an FE-PE2I and FP-CIT were included in the study. Four patients had normal DAT imaging, of which three did not fulfil the IPS criteria at the clinical reassessment after 2 years. Six raters evaluated the DAT images blinded to the clinical diagnosis, interpreting the image as being ‘normal’ or ‘pathological’, and assessed the degree of DAT-reduction in the caudate and putamen. The inter-rater agreement was assessed with intra-class correlation and Cronbach’s α. For calculation of sensitivity and specificity, DAT images were defined as correctly classified if categorized as normal or pathological by ≥4/6 raters.Results: The overall agreement in visual evaluation of the FE-PE2I- and FP-CIT images was high for the IPS patients (α = 0.960 and 0.898, respectively), but lower in healthy controls (FE-PE2I: α = 0.693, FP-CIT: α = 0.657). Visual interpretation gave high sensitivity (both 0.96) but lower specificity (FE-PE2I: 0.86, FP-CIT: 0.63) with an accuracy of 90% for FE-PE2I and 77% for FP-CIT.Conclusion: Visual evaluation of FE-PE2I PET imaging demonstrates high reliability and diagnostic accuracy for IPS.
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| 2. |
- Almquist, H, et al.
(författare)
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Performance of simultaneous emission-transmission systems for attenuation-corrected SPEct: a method for validation applied to two camera systems
- 2001
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 22:7, s. 759-766
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Tidskriftsartikel (refereegranskat)abstract
- Several commercially available systems for attenuation correction in single photon emission computed tomography (SPECT) based on a transmission scan have been introduced that vary in performance. A test procedure for attenuation correction in SPECT is described and applied to two principally different gamma camera systems (the Siemens Multispect 3 triple-headed system [3HS] and the ADAC Genesys Vertex double-headed system [2HS]). The test procedure was based on geometrically well-defined phantoms. A torso phantom was used to illustrate the attenuation correction methods. The test procedure can be used without detailed knowledge of or access to the algorithms used for attenuation correction. The influence on the transmission measurement of radioactivity in a phantom was higher for the 2HS than for the 3HS. The 3HS produced satisfactory attenuation maps and corrected emission count rates to a constant value independent of phantom density and size. With the 2HS, there was a progressive decrease in the correction of emission count rates with increasing phantom density, and about 30% lower corrected count rates in the large compared with the small phantom. A decrease in measured attenuation coefficients in the vicinity of an emission source was demonstrated in large but not small phantoms. A likely explanation is erroneous correction of downscatter into the transmission energy window. This study demonstrates the need for independent evaluation of systems for attenuation correction in SPECT.
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| 3. |
- Barta, Pavel, et al.
(författare)
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Circumventing the requirement of binding saturation for receptor quantification using interaction kinetic extrapolation
- 2011
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 32:9, s. 863-867
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of the number of receptors per cell (NRPC) is important when assessing whether a tumor surface biomarker is suitable for medical imaging. One common method for NPRC quantification is to use a binding saturation assay, which is time consuming and requires large amounts of reagents. The aim of this study was to evaluate an alternative method based on kinetic extrapolation (KEX) and compare it with the classical manual saturation technique with regard to accuracy as well as time and reagent consumption. Epidermal growth factor receptor (EGFR) and HER2 receptor surface expression were quantified on five tumor cell lines using three (125)I-labeled and (131)I-labeled ligands (cetuximab and EGF for EGFR, trastuzumab for HER2 receptor) for both techniques. The KEX method involved interaction measurements in the LigandTracer, followed by KEX through computerized real-time interaction analysis to correct for nonsaturation on cells. Variability and NRPC estimates of the EGFR and HER2 receptor levels using the KEX method were comparable with the results from the classical saturation technique. However, the ligand consumption for the KEX method was 26-46% of the classical saturation technique. Furthermore, the KEX method reduced the workload radically. From the observations described in this study, we believe that the KEX method enables fast, credible, and easy NRPC quantification with a reduction in reagent consumption.
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| 4. |
- Begic, Amela, et al.
(författare)
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Impact of ventilation/perfusion single-photon emission computed tomography on treatment duration of pulmonary embolism.
- 2015
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 36:2, s. 162-167
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to establish whether the duration of anticoagulant (AC) therapy can be tailored, on an objective basis, by using ventilation/perfusion single-photon emission computed tomography (V/P SPECT) and to assess the extent of residual perfusion defects over time. In particular, we addressed the following: (a) is the extent of perfusion recovery at 3 months of initial pulmonary embolism (PE) diagnosis a satisfactory criterion for deciding the duration of oral AC? (b) Is it safe to withdraw AC at 3 months if perfusion recovery is complete?
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| 5. |
- Begic, Amela, et al.
(författare)
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Tomographic ventilation/perfusion lung scintigraphy in the monitoring of the effect of treatment in pulmonary embolism: serial follow-up over a 6-month period.
- 2011
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 32, s. 508-514
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Pulmonary embolism (PE) is a severe condition with nonspecific symptoms. Diagnosis relies on medical imaging but follow-up is currently based on clinical symptoms and general risk factors. The duration of anticoagulant treatment after an acute episode of PE is still subject to debate and the best method of identifying the risk of recurrence in individual patients is undefined. Tomographic lung scintigraphy [ventilation/perfusion single photon emission computed tomography (V/P SPECT)] has improved the diagnostic accuracy with regard to PE but has not been evaluated for PE follow-up. AIM: The aim of this prospective study was to quantitatively follow the natural history of treated PE using V/P SPECT, which could prove helpful in defining an anticoagulant treatment regime for individual patients. METHODS: Of 83 consecutive patients with clinically suspected PE examined with V/P SPECT, 23 patients with confirmed PE were followed by serial V/P SPECT examinations over a 6-month period. All patients were also followed clinically. RESULTS: The mean relative decrease in PE extent compared with the time of diagnosis was 54±26% at 2 weeks, 79±30% at 3 months, and 82±30% at 6 months. Significant resolution of mismatched perfusion defects occurred between V/P SPECT controls within the first 3 months of anticoagulation (P<0.001) but not thereafter. V/P SPECT identified four patients with chronic PE, even though all patients were free from symptoms at 3-month follow-up. CONCLUSION: Follow-up of PE with V/P SPECT is feasible to evaluate treatment effectiveness in individual patients and to identify patients that develop chronic PE. This study also confirms that resolution of perfusion defects after PE occurs within the first 3 months of treatment. It is therefore recommended that V/P SPECT follow-up should be considered at 3 months after diagnosis.
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| 6. |
- Bäck, Anna-Karin, 1971-, et al.
(författare)
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Renography with a semiautomated algorithm for diuretic decision 7 min postradiopharmaceutical administration : a feasibility study
- 2020
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Ingår i: Nuclear medicine communications. - : Lippincott Williams & Wilkins. - 0143-3636 .- 1473-5628. ; 41:10, s. 1018-1025
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The F+10 method for diuretic renography (diuretics given 10 min after the radiopharmaceutical) could be a time-conserving method. This method involves a 30-min dynamic acquisition where diuretics are administered only when necessary by the Nuclear Medicine technologist performing the examination. The purpose of this study was to assess the method's performance and to discover the optimal threshold of residual activity for a diuretic administration 7 min into the F+10 renography by reprocessing raw data from prior performed examinations with 20-min acquisitions without diuretics.METHODS: Retrospectively, raw data from 320 original examinations of adult patients performed from 2013 to 2015 were reprocessed into 7-min series and categorized as requiring diuretic or not. The diuretic decisions made by an expert panel were used as a reference. A receiver-operating characteristic curve was drawn to assess the optimal cutoff value for the residual renal activity. Sensitivity, specificity, positive and negative predictive values, as well as the Youden J index were calculated.RESULT: The experts classified 50% (160 examinations) as in need of diuretics. The receiver-operating characteristic curve demonstrated the theoretical optimal cutoff value at 7 min to be 94% of maximum activity (sensitivity 0.93, specificity 0.81, Youden J index 0.73). A clinically acceptable threshold is suggested to be 85% (sensitivity 0.99, specificity 0.59, Youden J index 0.58).CONCLUSION: Tc-mercaptoacetyltriglycine renography with the F+10 method and the threshold 85% for diuretic decision 7 min into the renography is a feasible and acceptable method in clinical practice.
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| 7. |
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| 8. |
- 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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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- 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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| 14. |
- Gustafsson, Agnetha, et al.
(författare)
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Evaluation of various attenuation corrections in lung SPECT in healthy subjects
- 2003
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Ingår i: Nuclear Medicine Communications. - : Ovid Technologies (Wolters Kluwer Health). - 0143-3636 .- 1473-5628. ; 24:10, s. 1087-1095
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Tidskriftsartikel (refereegranskat)abstract
- The effect of increasingly more sophisticated attenuation correction methods on image homogeneity has been studied in seven healthy subjects. The subjects underwent computed tomography (CT), single photon emission computed tomography (SPECT) and transmission computed tomography (TCT) of the thorax region in the supine position. Density maps were obtained from the CT and TCT studies. Attenuation corrections were performed using five different methods: (1) uniform correction using only the body contour; (2) TCT based corrections using the average lung density; (3) TCT based corrections using the pixel density; (4) CT based corrections using average lung density; and (5) CT based corrections using the pixel density. The isolated attenuation effects were assessed on quotient images generated by the division of images obtained using various attenuation correction methods divided by the non-uniform attenuation correction based on CT pixel density (reference method). The homogeneity was calculated as the coefficient of variation of the quotient images (CVatt), showing the isolated attenuation effects. Values of CVatt were on average 12.8% without attenuation correction, 10.7% with the uniform correction, 8.1% using TCT map using the average lung density value and 4.8% using CT and average lung density corrections. There are considerable inhomogeneities in lung SPECT slices due to the attenuation effect. After attenuation correction the remaining inhomogeneity is considerable and cannot be explained by statistical noise and camera non-uniformity alone. ((C) 2003 Lippincott Williams Wilkins).
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| 15. |
- 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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| 16. |
- Hindorf, Cecilia, et al.
(författare)
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Quantitative imaging of 223Ra-chloride (Alpharadin) for targeted alpha-emitting radionuclide therapy of bone metastases.
- 2012
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 33:7, s. 726-732
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Ra is an alpha particle emitter that targets areas of increased bone turnover in bone metastases. Alpha particles account for 95% of the 27.8 MeV emitted per decay. Less than 2% of the emissions are from photons. This means that a high absorbed dose will be delivered locally, although the number of photons for imaging will be low. The purpose of this study was to investigate the possibility of quantitative imaging of Ra to enable biodistribution studies. METHODS: A Philips Forte gamma camera, equipped with a medium-energy collimator, was used. Basic imaging parameters were determined from phantom studies, and the accuracy of activity quantification was tested in a phantom study and within a patient study. RESULTS: Imaging parameters were determined for the three most suitable photon peaks from the acquired energy spectrum (82, 154 and 270 keV). Camera sensitivity is constant for circular sources with areas greater than 10 cm. The spatial resolution (full-width at half-maximum) was 1.1 cm for each of the three energy windows. The possibility for quantitative imaging was further investigated for the 82 keV energy window, which showed the highest sensitivity and spatial resolution. A phantom study showed that activity could be quantified to within 10% for a 200 ml volume placed within water containing background activity and to within 50% for a 0.5 ml phantom. Quantification of activity in bone after administrations of 100 kBq/kg of Ra-chloride proved the feasibility of quantitative imaging of patients who have received radionuclide therapy. CONCLUSION: Because of the high-energy deposition of Ra, only a low injected activity is required for therapy, which results in a low count rate for the gamma camera. Nevertheless, this study has demonstrated that it is possible to quantify uptake with a sufficient degree of accuracy to obtain clinically relevant information.
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| 17. |
- Jakobson Mo, Susanna, 1968-, et al.
(författare)
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I-123-FP-Cit and I-123-IBZM SPECT uptake in a prospective normal material analysed with two different semiquantitative image evaluation tools
- 2013
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Ingår i: Nuclear Medicine Communications. - : Lippincott Williams & Wilkins. - 0143-3636 .- 1473-5628. ; 34:10, s. 978-989
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Tidskriftsartikel (refereegranskat)abstract
- Objective The need for age-adjusted and/or sex-adjusted reference values in dopamine transporter (DAT) and dopamine D2 receptor (D2R) imaging with single-photon emission computed tomography (SPECT) in a longitudinal study of parkinsonian diseases was investigated. We used two different image evaluation tools with a cross-sectional and longitudinal statistical approach.Materials and methods Baseline DAT and/or D2R SPECT were performed in 51 healthy controls (HC), age-matched to patients in an ongoing prospective study on idiopathic parkinsonism. Twenty-four HC were re-examined after 3 years and 21 HC were examined again after 5 years. SPECT was performed with I-123-FP-Cit and I-123-IBZM on a two-headed hybrid gamma camera. Regions of interest and volumes of interest (VOIs) were used for image evaluation. A cross-sectional and longitudinal statistical analysis was carried out.Results Fewer sex-based differences and less age dependency were seen in DAT SPECT uptake ratios compared with D2R SPECT uptake ratios and when comparing uptake ratios obtained with regions of interest against those with VOIs. In the cross-sectional analysis, a significant age-dependent decline was seen in women in both DAT and D2R uptakes with the VOI method but not in men with either evaluation method. In the longitudinal dataset, both a slight decline and increase over time were seen in DAT uptake; however, a general pattern of decrease was seen in both men and women in D2R uptake.Conclusion The choice of the image evaluation method can influence the pattern of sex-based and age-related differences. The results speak for the use of age-stratified reference values for women, in particular when using a VOI method.
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| 18. |
- Jakobson Mo, Susanna, et al.
(författare)
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Long-term dopamine transporter imaging in Parkinson's disease treated with zona incerta stimulation
- 2016
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 37:5, s. 499-508
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The caudal zona incerta (cZI) is a promising, clinically beneficial target for deep brain stimulation (DBS) in Parkinson’s disease (PD). To assess whether DBS of the cZI affects the rate of dopamine terminal dysfunction, PD patients with and without DBS were followed prospectively with 123I FP-Cit single photon emission tomography from the first diagnosis and up to 8 years.Methods: Six patients underwent DBS of the cZI during the survey period. Twenty-two PD patients only on pharmacotherapy served as controls. 123I FP-Cit and clinical assessment were performed at baseline and after 1, 3 and 5 years in all patients. Ten patients also underwent a 123I FP-Cit after 8 years. Image data were evaluated semiquantitatively. Mixed-model analysis was used to assess the relative change in 123I FP-Cit uptake and comparison between surgically and conservatively treated PD patients.Results: The relative decrease in 123I FP-Cit uptake was more pronounced in DBS-treated patients than in controls in the more affected caudate (P=0.037) and putamen (P=0.013). The annual decrease rates were higher in the less affected than the more affected putamen, and were slightly greater in DBS-treated patients (4.8%, 95%confidence interval: 8.5–2.2%) than in controls (4.0%, 95% confidence interval: 5.1–3.1%).Conclusion: This long-term prospective study confirms that the underlying dopaminergic dysfunction continues despite clinical improvement in PD patients with DBS of the cZI. A slightly faster rate of decrease in 123I FP-Cit uptake in these patients compared with conservatively treated PD patients may reflect a more aggressive form of PD.
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| 19. |
- Jakobson Mo, Susanna, et al.
(författare)
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VNTR polymorphism in the SLC6A3 gene does not influence dopamine transporter availability measured by [18F]FE-PE2I PET or [123I]FP-Cit SPECT
- 2022
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Ingår i: Nuclear medicine communications. - : Wolters Kluwer. - 0143-3636 .- 1473-5628. ; 43:3, s. 247-255
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the potential impact of polymorphism in the 3'-untranslated region (3'UTR) of the SLC6A3 gene (DAT1) on normal variation in dopamine transporter (DAT) imaging with [18F]FE-PE2I PET and [123I]FP-Cit SPECT.METHODS: Thirty-six individuals (mean age 70.4±5.4 years) with normal [18F]FE-PE2I PET and [123I]FP-Cit SPECT were genotyped for variable number of tandem repeats (VNTR) in the 3′UTR of the DAT1 gene. The DAT-availability in the caudate and putamen as measured with [18F]FE-PE2I PET and [123I]FP-Cit SPECT, as well as in the substantia nigra with [18F]FE-PE2I PET were compared between the participants carrying one or two 9-repeat alleles (i.e. 9R+10R or 9R+9R; 47%) and the participants without a 9R allele (i.e. 10R+10R or 10R+11R; 53%). Nonparametric tests, linear regression analysis and mixed model analysis were used to assess any statistical difference in measured DAT availability between the two allele groups.RESULTS: The measured DAT-availability in PET- and SPECT-imaging tended to be slightly higher in the 9R-group; however, the difference did not reach statistical significance in either the caudate or the putamen or the substantia nigra. Instead, age did have a significant effect on the DAT level (P < 0.05) notwithstanding the genotype.CONCLUSION: No significant effect of DAT1-genotype was detectable in imaging with [18F]FE-PE2I PET or [123I]FP-Cit, instead, age accounted for the normal variation in DAT-PET and DAT-SPECT.
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| 20. |
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| 21. |
- 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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| 22. |
- Källén, Kristina, et al.
(författare)
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Assessment of glioma viability by estimating 201Tl SPET tumour uptake volume
- 1999
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 20:9, s. 837-844
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to develop a quantitative method to assess viable tumour based on post-operative 201Tl single photon emission tomography (SPET). We studied 15 patients with histologically defined highly malignant gliomas in the post-operative phase before initiation of adjuvant treatment. A 201Tl index was calculated in two ways: maximal counts versus mean counts within a region of interest (ROI). The tumour uptake volume (TUV) within the lesion was calculated from the number of voxels that had 201Tl uptake above a threshold calculated from the uptake on the contralateral side. The threshold was set at three levels: A = 1.4 times the mean 201Tl uptake in a three-dimensional reference ROI + 96.7% confidence interval (the TUV was corrected by subtraction of the volume in the reference ROI that had uptake above the threshold with compensation for unequal ROI sizes); B = 1.4 times the mean reference ROI + 99% confidence interval; and C = maximum 201Tl uptake in the reference ROI. The SPET results were compared with the tumour volumes calculated from CT scans. Thirteen tumours showed high post-operative 201Tl uptake. The 201Tl index was not significantly correlated with histological grade within the group of highly malignant gliomas. 201Tl SPET tumour uptake volume method B was highly significantly correlated with CT estimated tumour volume. In conclusion, the measurement of post-operative 201Tl SPET tumour uptake volume demonstrates metabolically active glioma tissue and is an alternative method for the monitoring of glioma treatment response.
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| 23. |
- Källén, Kristina, et al.
(författare)
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Quantitative 201Tl SPET imaging in the follow-up of treatment for brain tumour: a sensitive tool for the early identification of response to chemotherapy?
- 2000
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 21:3, s. 259-267
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to establish if repeated quantitative 201Tl SPET scanning during follow-up of astrocytoma therapy can provide information that is relevant for clinical management. Sixteen consecutive patients, with histopathologically verified highly malignant astrocytoma, were followed during PCV chemotherapy. Imaging with 201Tl SPET and CT was performed repeatedly over 8-16 weeks until treatment discontinuation, with a maximum follow-up of 74 weeks. Tumour uptake volume (TUV), a measure of metabolically active tumour tissue, was calculated from the SPET images. The reliability of early identification of treatment failure, defined as > 25% tumour volume increase, following one course (week 8) and three courses (week 24) of chemotherapy, was calculated for the two imaging methods. 201Tl SPET positive patients (> 25% tumour volume increase) were compared with 201Tl SPET negative patients in terms of time to treatment discontinuation (TTD) and survival time (ST). The patients were followed with a total of 59 SPET examinations, and treatment was continued for a median 27 weeks (range 16-78 weeks). The comparative reliability of SPET and CT showed the highest sensitivity and accuracy for SPET in the early identification of astrocytoma treatment failure at the week 24 assessment. Patients with positive 201Tl SPET after three courses of chemotherapy had a significantly reduced TTD (P = 0.040) but not significantly reduced ST. Of the ten patients who received concomitant radiation and chemotherapy, five had a small (0-10 ml) TUV at the week 24 assessment. Patients with a TUV > 10 ml at this assessment had a shorter TTD (P = 0.016) and a reduced ST (P = 0.024) compared to patients with a TUV < 10 ml. In conclusion, the assessment of progressive disease by quantitative 201Tl SPET appears to provide information on treatment response, earlier and with a higher reliability than CT. Repeated 201Tl SPET scanning during follow-up of astrocytoma treatment is an alternative tool for the early identification of treatment failure.
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| 24. |
- Larsson, Anne, et al.
(författare)
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A method for attenuation and scatter correction of brain SPECT based on computed tomography images
- 2003
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 24:4, s. 411-420
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Tidskriftsartikel (refereegranskat)abstract
- A method for attenuation and scatter correction of brain single photon emission computed tomography (SPECT) is described where computed tomography (CT) images of the brain are used for the calculation of attenuation maps. The method is evaluated for the substance 99mTc hexamethylpropylene amine oxime. A transmission dependent scatter correction is utilized and is based on ray sums calculated through the attenuation map. A method based on external markers is used to align the SPECT and CT image volumes. The markers need only to be present during the SPECT acquisition since the corresponding landmarks can be found without markers on the CT images. The mismatching has been investigated for five patients who have undergone both a CT examination and a SPECT examination with markers. Twelve individuals from the staff have pointed out the landmarks on the CT images, with an average standard deviation of 3.4 mm. Reconstructions with an attenuation map shifted the corresponding 95% confidence interval have been performed to obtain an estimation of the quantitative uncertainty caused by the mismatching, and quantitative errors of up to 6.3% have been measured. At present the method is probably most useful when groups of patients are studied.
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| 25. |
- 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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| 26. |
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| 27. |
- 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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| 28. |
- 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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| 29. |
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| 30. |
- Persson, Eva, et al.
(författare)
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Quantification of myocardial hypoperfusion with 99m Tc-sestamibi in patients undergoing prolonged coronary artery balloon occlusion.
- 2002
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 23:3, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- SUMMARY: Percutaneous transluminal coronary angioplasty provides an excellent opportunity to investigate the location and quantity of hypoperfusion during sudden complete occlusion of one of the major coronary arteries. Thirty-five patients referred for elective percutaneous transluminal coronary angioplasty were injected intravenously with 99mTc-sestamibi during balloon inflation. To visualize and quantify the hypoperfused region, a map of perfusion was constructed from that occlusion study and from the control study performed on the following day. Patients were divided into groups according to proximal or distal occlusion within each of the three coronary arteries. The region of myocardium supplied by each coronary artery varied in location and extended outside the typical borders for all arteries, but most prominently for the left circumflex coronary artery. The quantities of hypoperfusion varied within each artery group, but the average hypoperfusion was greater for the left anterior descending coronary artery than for either the right coronary artery or the left circumflex coronary artery. It is concluded that the quantities of hypoperfusion were highly variable within each artery group. Occlusion of the left anterior descending coronary artery was associated with the largest ischaemic region. The area of hypoperfusion extended outside the typical borders, most prominently for the left circumflex coronary artery.
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| 31. |
- Sadik, May, 1970, et al.
(författare)
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A new computer-based decision-support system for the interpretation of bone scans
- 2006
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Ingår i: Nucl Med Commun. - 0143-3636. ; 27:5, s. 417-423
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To develop a completely automated method, based on image processing techniques and artificial neural networks, for the interpretation of bone scans regarding the presence or absence of metastases. METHODS: A total of 200 patients, all of whom had the diagnosis of breast or prostate cancer and had undergone bone scintigraphy, were studied retrospectively. Whole-body images, anterior and posterior, were obtained after injection of 99mTc-methylene diphosphonate. The study material was randomly divided into a training group and a test group, with 100 patients in each group. The training group was used in the process of developing the image analysis techniques and to train the artificial neural networks. The test group was used to evaluate the automated method. The image processing techniques included algorithms for segmentation of the head, chest, spine, pelvis and bladder, automatic thresholding and detection of hot spots. Fourteen features from each examination were used as input to artificial neural networks trained to classify the images. The interpretations by an experienced physician were used as the 'gold standard'. RESULTS: The automated method correctly identified 28 of the 31 patients with metastases in the test group, i.e., a sensitivity of 90%. A false positive classification of metastases was made in 18 of the 69 patients not classified as having metastases by the experienced physician, resulting in a specificity of 74%. CONCLUSION: A completely automated method can be used to detect metastases in bone scans. Future developments in this field may lead to clinically valuable decision-support tools.
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| 32. |
- Sandgren, Kristina, et al.
(författare)
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Histopathology-validated lesion detection rates of clinically significant prostate cancer with mpMRI, [68Ga]PSMA-11-PET and [11C]Acetate-PET
- 2023
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Ingår i: Nuclear medicine communications. - : Lippincott Williams & Wilkins. - 0143-3636 .- 1473-5628. ; 44:11, s. 997-1004
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Tidskriftsartikel (refereegranskat)abstract
- Objective: PET/CT and multiparametric MRI (mpMRI) are important diagnostic tools in clinically significant prostate cancer (csPC). The aim of this study was to compare csPC detection rates with [68Ga]PSMA-11-PET (PSMA)-PET, [11C] Acetate (ACE)-PET, and mpMRI with histopathology as reference, to identify the most suitable imaging modalities for subsequent hybrid imaging. An additional aim was to compare inter-reader variability to assess reproducibility.Methods: During 2016–2019, all study participants were examined with PSMA-PET/mpMRI and ACE-PET/CT prior to radical prostatectomy. PSMA-PET, ACE-PET and mpMRI were evaluated separately by two observers, and were compared with histopathology-defined csPC. Statistical analyses included two-sided McNemar test and index of specific agreement.Results: Fifty-five study participants were included, with 130 histopathological intraprostatic lesions >0.05 cc. Of these, 32% (42/130) were classified as csPC with ISUP grade ≥2 and volume >0.5 cc. PSMA-PET and mpMRI showed no difference in performance (P = 0.48), with mean csPC detection rate of 70% (29.5/42) and 74% (31/42), respectively, while with ACE-PET the mean csPC detection rate was 37% (15.5/42). Interobserver agreement was higher with PSMA-PET compared to mpMRI [79% (26/33) vs 67% (24/38)]. Including all detected lesions from each pair of observers, the detection rate increased to 90% (38/42) with mpMRI, and 79% (33/42) with PSMA-PET.Conclusion: PSMA-PET and mpMRI showed high csPC detection rates and superior performance compared to ACE-PET. The interobserver agreement indicates higher reproducibility with PSMA-PET. The combined result of all observers in both PSMA-PET and mpMRI showed the highest detection rate, suggesting an added value of a hybrid imaging approach.
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| 33. |
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| 34. |
- Sjöström, A, et al.
(författare)
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Direct astatination of a peptide, human epidermal growth factor, using nido-carborane as a prosthetic group
- 2000
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 21:6, s. 594-
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- Purpose The aim of the study was to evaluate direct astatine labelling of proteins with the use of nido-carborane as prosthetic group for attachments of astatine. Methods: Human epidermal growth factor, hEGF, was conjugated to 7-(3-amino-propyl)-7,8-dicarbanido-undecaborate (-), ANC, using two different conjugation methods, glutaraldehyde crosslinking and coupling via Traut's reagent. The hEGF-ANC conjugates were astatine labelled using the Chloramine-T method. The stability of the labelled compounds was tested by incubation at 37°C. Results: The conjugates were astatinated using the Chloramine-T method in high yield. The best labelling yields were obtained by the glutaraldehyde conjugate with an average yield of 70.5±2.2%. In vitro stability tests indicated that the introduced label was as stable as hEGF labelled with astatobenzoate. Conclusion: Conjugation of nido-carboranes to peptides creates binding sites for direct astatine labelling that can be performed in mild conditions (p 7.2) with high labelling yields.
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| 35. |
- Starck, Sven-Åke, et al.
(författare)
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An evaluation of reconstruction techniques and scatter correction in bone SPECT of the spine
- 2003
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 24:5, s. 565-570
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Tidskriftsartikel (refereegranskat)abstract
- A selection of commonly used reconstruction and filter techniques in the processing of 99mTc oxidronate (i.e., 99mTc hydroxymethane diphosphonate) single photon emission computed tomography (SPECT) of the spine was compared. The possible additional value of scatter correction on image contrast was also evaluated. Twenty-eight bone SPECT examinations of consecutive patients were studied retrospectively. The reconstruction techniques used were filtered back-projection and iterative reconstruction with the use of ordered subsets estimation maximization. Three-dimensional post-filtering with a Metz filter and a Butterworth filter was used. Each combination was evaluated with or without scatter correction. Each study was also processed with the department's standard technique of two-dimensional pre-filtering with a Metz filter followed by filtered back-projection (without scatter correction). Five observers evaluated the image quality of reconstructed coronal and sagittal slices, with special reference to the resolution of vertebrae, vertebral processes, the spinal canal and suspected abnormal uptakes. A grading scale from -2 to +2 was used with the standard technique as the reference. The best image quality was found with iterative reconstruction in combination with a contrast enhancing Metz filter or a noise reducing Butterworth filter. Scatter correction did not improve image quality.
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| 36. |
- Starck, Sven-Åke, et al.
(författare)
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Digital filtering of bone scans : an ROC study
- 1997
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Ingår i: Nuclear medicine communications. - : Ovid Technologies (Wolters Kluwer Health). - 0143-3636 .- 1473-5628. ; 18:2, s. 98-104
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to investigate if digital filtering can increase the sensitivity and specificity of bone scans, and to find the type of filter most suitable for bone images at various count levels. We also wished to examine if filtering allows the administered activity or the examination time to be reduced, and if it is easier to detect low-contrast uptake using a digital filter. Images containing a total of 100, 350 and 1000 kcounts were acquired in a 256 x 256 matrix using a transmission phantom simulating the thoracolumbar region. Receiver operating characteristic (ROC) analysis demonstrated that digital filtering increases the sensitivity and specificity of bone scintigraphy. A low-pass filter for images with low statistics (100 kcounts), which contain 2-5 counts per pixel in the ribs and vertebrae respectively, and a Metz filter for images with normal (5-19 counts per pixel) to good (20-54 counts per pixel) statistics, increase the area under the ROC curve significantly (99% confidence level) compared to unfiltered images. Filtering also increases the detectability of low-contrast objects compared with unfiltered images. Digital filtering might be an alternative to raising the number of counts in the image. An alternative is to reduce the administered activity and hence the effective dose to the patient, or to reduce the examination time-which is an advantage when treating elderly patients or patients with pain.
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Thorsson, Ola, et al.
(författare)
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Advantages of standardized criteria for the interpretation of angiotensin-converting enzyme inhibition renography
- 2009
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Ingår i: NUCLEAR MEDICINE COMMUNICATIONS. - 0143-3636 .- 1473-5628. ; 30, s. 449-454
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Tidskriftsartikel (refereegranskat)abstract
- Background The aim of this study was to evaluate the efficiency of captopril renography to detect renovascular hypertension (RVH) using the standardized test criteria established at the consensus conference in Santa Fe 1995. The evaluation was made prospectively and in a clinical situation.less thanpgreater thanMethods Renal scintigraphy was performed with Tc-99m-MAG3 according to a 2-day protocol in patients receiving 25 mg captopril 1 h before the test. A baseline study was added only in patients showing abnormal findings in the captopril-stimulated study. All tests were re-evaluated according to the consensus criteria by two nuclear medicine specialists who were unaware of the original evaluation that was made by different doctors on duty at the nuclear medicine section at the time.less than/pgreater than less thanpgreater thanResults Using a 12-month clinical follow-up as a reference, 16 patients in a group of 164 hypertensive patients had RVH, that is, a prevalence of 10%. The re-evaluation and original evaluation indicated a sensitivity of 94 versus 100%, specificity of 97 versus 88%, accuracy of 97 versus 89%, positive predictive value of 83 versus 47%, and negative predictive value of 99 versus 100%. In 15 studies, results from the two evaluations were discordant and in 14 of these studies an originally false positive or intermediate study was re-evaluated as negative. The test result was highly decisive in the future management of patients, minimizing the number of renal angiograms that had to be performed and initiating a search for other causes of secondary hypertension. Conclusion Captopril renography is a useful and reliable test in patients with suspicion of RVH. Strict adherence to the diagnostic criteria and recommendations from the 1995 consensus conference further improved the performance of the test compared with clinical follow-up.
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| 41. |
- Timmer, Stefan A J, et al.
(författare)
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Reappraisal of a single-tissue compartment model for estimation of myocardial oxygen consumption by [11C]acetate PET : an alternative to conventional monoexponential curve fitting
- 2011
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 32:1, s. 59-62
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Tidskriftsartikel (refereegranskat)abstract
- Background:Myocardial washout kinetics of carbon-11 labelled acetate ([11C]acetate) by positron emission tomography (PET) closely correlate with myocardial oxygen consumption (MVO2). Analysis of the tissue time activity curve by conventional monoexponential curve fitting, however, does not account for spillover effects and recirculating 11C activity. In theory, a compartment model considering variations of the arterial input function and metabolic 11C contamination, could improve consistency of MVO2 estimations. The objective of the study was to investigate this hypothesis.Methods: Nineteen healthy volunteers were studied under resting conditions with [11C]acetate PET. Time activity curves were analysed by automated monoexponential curve fitting and a single-tissue compartment model to obtain Kmono and k2, as noninvasive indices of MVO2. Subsequently, Kmono and k2 were related to the rate-pressure product, as an indirect marker of MVO2.Results:The rate-pressure product was significantly correlated to Kmono (r=0.46, P=0.047) and k2 (r=0.75, P<0.001).Conclusion:The results of this study suggest that a single-tissue compartment model yields more accurate noninvasive estimates of MVO2 by the use of [11C]acetate PET in humans, in comparison with monoexponential curve fitting.
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| 42. |
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| 43. |
- Wang, Ellen, et al.
(författare)
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Automated functional characterization of radiolabeled antibodies : a time-resolved approach
- 2014
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 35:7, s. 767-776
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Tidskriftsartikel (refereegranskat)abstract
- Background The number of radiolabeled monoclonal antibodies (mAbs) used for medical imaging and cancer therapy is increasing. The required chemical modification for attaching a radioactive label and all associated treatment may lead to a damaged mAb subpopulation. This paper describes a novel method, concentration through kinetics (CTK), for rapid assessment of the concentration of immunoreactive mAb and the specific radioactivity, based on monitoring binding kinetics. Methods The interaction of radiolabeled mAb with either the antigen or a general mAb binder such as Protein A was monitored in real time using the instrument LigandTracer. As the curvature of the binding trace has a distinct shape based on the interaction kinetics and concentration of the functional mAb, the immunoreactive mAb concentration could be calculated through reverse kinetic fitting of the binding curves, using software developed for this project. The specific activity, describing the degree of radioactive labeling, was determined through the use of calibrated signal intensities. Results The performance of the CTK assay was evaluated on the basis of various mAb-based interaction systems and assay formats, and it was shown that the assay can provide accurate and repeatable results for immunoreactive concentration and specific activity, with both accuracy and relative SD values below 15%. Conclusion By applying reverse kinetics on real-time binding traces it is possible to estimate the functional concentration and specific activity of radiolabeled mAb. The CTK assay may in the future be included as a complement to current quality assessment methods of radiolabeled mAbs.
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| 44. |
- Wolfensberger, Saskia P, et al.
(författare)
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Quantification of the neurokinin 1 receptor ligand [¹¹C]R116301
- 2011
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Ingår i: Nuclear medicine communications. - 0143-3636 .- 1473-5628. ; 32:10, s. 896-902
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:Neurokinin 1 (NK1) receptors have been implicated in depression, anxiety, and pain perception. Recently, it was shown that, in the human brain, a specific NK1 receptor-related signal was obtained with the novel radioligand, [¹¹C]R116301, using positron emission tomography. The purpose of this study was to evaluate various methods for quantifying specific [¹¹C]R116301 binding.METHODS:Two dynamic 90-min [¹¹C]R116301 scans, separated by 5 h, were performed in 11 healthy volunteers. In three patients, the second scan was performed after an oral blocking dose of 125 mg of aprepitant, whereas in the other eight, no intervention was performed (test-retest). Whole striatum was used as the tissue of interest, as it has the highest density of NK1 receptors. Cerebellum was used as the reference tissue.RESULTS:Reference tissue models were stable with the simplified reference tissue model (SRTM) performing best. Average (± standard deviation) SRTM-derived mean nondisplaceable binding potential (BP(ND)) of all (first) baseline scans was 0.64±0.31 (n=11), which reduced to -0.01±0.03 (n=3) after aprepitant administration. Test-retest results showed low variability (14.0±10.7%) and excellent reliability, as indicated by the intraclass correlation coefficient (0.93). The ratio of standardized uptake values of striatum and cerebellum minus 1, an approximation of BP(ND), showed very low variability (6.2±3.1%) with excellent reliability (intraclass correlation coefficient=0.98), and correlated well with SRTM-derived BP(ND) (R²=0.96).CONCLUSION:SRTM is the model of choice for quantifying [¹¹C]R116301 binding. Semiquantitative tissue ratios hold promise for routine clinical applications.
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| 45. |
- Ärlig, A, et al.
(författare)
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Selection of collimator for rCBF studies and evaluation of triple-headed SPET using noise-resolution plots
- 1997
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Ingår i: Nuclear Medicine Communications. - 1473-5628. ; 18:7, s. 655-661
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effect of collimator selection on image quality in regional cerebral blood flow (rCBF) studies of the brain performed with 99Tc(m)-HMPAO. A triple-headed SPET system (GE/CGR Neurocam) was used, together with three sets of parallel-hole collimators - general-purpose (GP), high-resolution (HR) and ultra-high-resolution (UHR). Two image quality parameters were used to describe the image quality, namely, noise and resolution. Noise was measured in experimental and Monte-Carlo simulated SPET studies of a cylinder phantom of uniform activity as the pixel root mean square error (RMS) and as the coefficient of variation (CV) of quantitative rCBF values. Resolution was measured as full-width at half-maximum in experimental SPET studies of a line-source. Plots of noise versus resolution for the different collimators were obtained by varying the cut-off frequency of the Hanning filter applied in the reconstruction of transaxial slices. From these noise-resolution plots, we were able to determine which collimator gave the best resolution for a specific noise level. A lowest reasonable noise level may be established by comparison with the inter-observer CV of the quantification method.
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