Traditional interpretation of rCBF SPECT data is of a qualitative nature and is dependent on the observer's understanding of the normal distribution of the tracer. The use of a normal database in quantitative regional analysis facilitates the detection of functional abnormality in individual and group studies by accounting for inter-subject variability. The ability to simulate realistic images would allow various important areas related to the use of normal databases to be studied. These include the optimisation of the detection of abnormal blood flow and the portability of normal databases between gamma camera systems. To investigate this further we have constructed a hardware phantom and scanned various configurations of radioactive brain patterns and simulated skull configurations.Methods: A subresolution sandwich phantom was constructed with a simulated skull which was assembled using a high-resolution segmented MR scan printed with a (TcO4)-Tc-99m- mixture and scanned using a double-headed gamma camera with parallel-hole collimators. Various different grey-to-white matter (GM:WM) ratios and aluminium simulated skull configurations were used. A single difference measure between the phantom data and a control database mean image was used for optimisation. The realism of phantom data was assessed using statistical parametric mapping (SPM) and ROI analysis.Results: Optimisation was achieved with a range of WM:GM ratios from 1.9 to 2.4:1 with various simulated skull configurations.Conclusion: The ability to simulate realistic HMPAO SPECT scans has been demonstrated using a subresolution sandwich phantom. Further work, involving scanning the optimised phantom on different gamma camera systems and comparison with camera-specific normal databases should further refine the phantom configuration. (c) 2013 Elsevier Inc. All rights reserved.

Southampton General Hospital, Department of Nuclear Medicine British Nuclear Medicine Society Oral and Poster Abstracts 2007

Departments of aMedical Physics & Bioengineering bNuclear Medicine, Southampton General Hospital, UK Abstracts of the 34th Annual Meeting of the British Nuclear Medicine Society Manchester International Conference Centre, UK, 27–29 March 2006

Dawson, A.H.; Fleming, J.S.; Hoffmann, S.M.A.; Papaspyrou, L.; Peel, S. Author Information

Kemp, P.M.; Hoffmann, S.M.A.; Holmes, C.; Ward, A.; Bolt, L.; Fleming, J.S. Author Information

Department of Medical Physics and Bioengineering, Southampton University Hospitals Trust, UK Abstracts of the spring 2005 meeting of the British Nuclear Medicine Society Manchester International Convention Centre, UK; 14–16 March, 2005

Simulation is useful in the validation of functional image analysis methods, particularly when considering the number of analysis techniques currently available lacking thorough validation. Problems exist with current simulation methods due to long run times or unrealistic results making it problematic to generate complete datasets. A method is presented for simulating known abnormalities within normal brain SPECT images using a measured point spread function (PSF), and incorporating a stereotactic atlas of the brain for anatomical positioning. This allows for the simulation of realistic images through the use of prior information regarding disease progression, SPECT images of cerebral perfusion have been generated consisting of a control database and a group of simulated abnormal subjects that are to be used in a UK audit of analysis methods. The abnormality is defined in the stereotactic space, then transformed to the individual subject space, convolved with a measured PSF and removed from the normal subject image. The dataset was analysed using SPM99 (Wellcome Department of Imaging Neuroscience, University College, London) and the MarsBaR volume of interest (VOI) analysis toolbox. The results were evaluated by comparison with the known ground truth. The analysis showed improvement when using a smoothing kernel equal to system resolution over the slightly larger kernel used routinely. Significant correlation was found between effective volume of a simulated abnormality and the detected size using SPM99. Improvements in VOI analysis sensitivity were found when using the region median over the region mean. The method and dataset provide an efficient methodology for use in the comparison and cross validation of semi-quantitative analysis methods in brain SPECT, and allow the optimization of analysis parameters.

aDepts of aMedical Physics & Bioengineering bNuclear Medicine, Southampton General Hospital, UK Abstracts of the spring 2005 meeting of the British Nuclear Medicine Society Manchester International Convention Centre, UK; 14–16 March, 2005

Depts of aMedical Physics & Bioengineering bNuclear Medicine, Southampton General Hospital, UK Abstracts of the spring 2005 meeting of the British Nuclear Medicine Society Manchester International Convention Centre, UK; 14–16 March, 2005

Motion correction techniques have tended to use phantom data to prove their efficacy, with the assumption made that they can correct the more complex movements seen on clinical data. This study assessed the effectiveness of a motion correction algorithm using clinical data. The study group consisted of 40 patients who had movement on their first scan but then had a re-scan which was unaffected by movement. The data effected by movement was corrected using the motion correction algorithm and processed in an identical way to the data unaffected by motion. Both sets of data were analysed by statistical parametric mapping (SPM) which compared the data sets to a group of 31 normal controls. The data were then reported blinded by a nuclear medicine consultant with a special interest in neurological imaging, and a diagnosis made. The diagnoses based on the SPM maps showed an agreement of 80%. However, in depth analysis of the movement corrected data and the re-scan (with no movement) showed that lesions could be introduced or removed by the correction algorithm. Contrary to recent published reports, based on phantom work, our clinical data showed that movement correction programs in clinical practice should be viewed with extreme caution.

Background:Quantitative analysis is widely applied to SPECT perfusion imaging of the brain. Simulation offers a useful system for validating and comparing these methods. A method for simulating realistic abnormal brain SPECT images is presented.Methods: Twenty-nine normal control studies were available. Perfusion abnormalities were introduced in a subset of these subjects to simulate the four most common forms of dementia and varying levels of impairment. The abnormalities were defined in Talairach space, as voxels with percentage perfusion reduction in known anatomical positions. They were spatially transformed to the control subject space, convolved with a measured PSF, and introduced into the normal image. This allowed simulation of abnormal perfusion distribution in a variety of anatomical shapes. Validation of simulation was performed by viewing by an experienced observer. Analysis was performed using SPM99 comparing with the remainder of the controls. Results:The simulated image set was considered visually realistic. SPM99 analysis detected the abnormalities with a sensitivity of 95% and a specificity of 88%. Conclusion:A method has been developed for simulating abnormal SPECT brain images in a variety of realistic anatomical shapes. The data should be suitable for audit of HMPAO SPECT brain perfusion imaging.

This study implemented the latest version of statistical parametric mapping software, SPM2, and compared registration and statistical analyses of HMPAO SPECT brain images with our standard SPM99 method. Default parameters for registration and statistical analysis were altered to be similar to SPM99. Simulated defects were added to two normal control HMPAO SPECT images (A and B) and each image was compared with 19 other normal control images using both SPM99 and SPM2. Registration was similar for both versions of software when equivalent parameters were used. For statistical comparison of images A and B with the control group the FWHM of the images were estimated to be 24.1–25.1 mm and 17.8–18.4 mm for SPM99 and SPM2 respectively (true resolution was 19 mm). Comparing SPM99 and SPM2, 5 and 8 of the true defects in image A, and 1 and 5 of the true defects in image B were detected using the same threshold cut-off for the statistical maps. For image B a false positive defect was identified with SPM2. This suggests that SPM2 will be more sensitive in identifying hypoperfusion defects than SPM99, possibly at the expense of slightly reduced specificity. The overall improvement in diagnostic accuracy probably relates to the improved estimation of resolution.

Objective: To compare the HMPAO SPECT cerebral perfusion patterns in early and late onset Alzheimer's disease.Methods: Twenty patients with early onset disease (<65 years) and 44 patients with late onset disease (>65 years) were studied. All patients fulfilled NINCDS-ADRDA clinical criteria and had details of disease severity and length of history at the time of imaging. Technetium-99m HMPAO SPECT brain scans were acquired on a multi-detector gammacamera and analysed visually and with statistical parametric mapping (SPM99).Results: Patients with early onset disease had significantly greater posterior cortical association area involvement whereas those with late onset disease had significantly greater medial temporal hypoperfusion. These findings were unchanged after controlling for disease severity and length of illness.Discussion: These functional imaging findings of the differences between early and late onset Alzheimer's disease are supported by published findings that include histopathological and clinical evidence; namely late onset patients tend to present with the characteristic involvement of the medial temporal lobes producing marked memory loss whereas early onset patients present with predominant posterior cortical association area involvement. These age related findings should be borne in mind when clinically diagnosing, and interpreting functional brain imaging studies in, patients with suspected Alzheimer's disease.

s of the 31st Annual Meeting of the British Nuclear Medicine Society, Manchester, UK, 29 April to 1 May 2003 - LUNG

s of the 31st Annual Meeting of the British Nuclear Medicine Society, Manchester, UK, 29 April to 1 May 2003 - NEUROLOGY

s of the 31st Annual Meeting of the British Nuclear Medicine Society, Manchester, UK, 29 April to 1 May 2003 - NEUROLOGY

Holmes, R. B.; Kemp, P. M.; Hoffmann, S. M.A.; Fleming, J. S.; Bolt, L.; Ward, A. Author Information