Brain PET and SPECT imaging and quantification: a survey of the current status in the UK.

OBJECTIVES: With disease-modifying therapies in development for neurological disorders, quantitative brain imaging techniques become increasingly relevant for objective early diagnosis and assessment of response to treatment. The aim of this study was to evaluate the use of Brain SPECT and PET scans in the UK and explore drivers and barriers to using quantitative analysis through an online survey. METHODS: A web-based survey with 27 questions was used to capture a snapshot of brain imaging in the UK. The survey included multiple-choice questions assessing the availability and use of quantification for DaTscan, Perfusion SPECT, FDG PET and Amyloid PET. The survey results were reviewed and interpreted by a panel of imaging experts. RESULTS: Forty-six unique responses were collected and analysed, with 84% of responses from brain imaging sites. Within these sites, 88% perform DaTscan, 50% Perfusion SPECT, 48% FDG PET, and 33% Amyloid PET, while a few sites use other PET tracers. Quantitative Brain analysis is used in 86% of sites performing DaTscans, 40% for Perfusion SPECT, 63% for FDG PET and 42% for Amyloid PET. Commercial tools are used more frequently than in-house software. CONCLUSION: The survey showed variations across the UK, with high availability of DaTscan imaging and quantification and lower availability of other SPECT and PET scans. The main drivers for quantification were improved reporting confidence and diagnostic accuracy, while the main barriers were a perception of a need for an appropriate database of healthy controls and a lack of training, time, and software availability.

Imaging Care Requirements: Use of Functional Neuroimaging to Predict Dementia Caregiver Burden.

BACKGROUND: Dementia caregivers frequently report high stress, with increased burden associated with worse outcomes for both patients and caregivers. Although many studies relate clinical phenotypes to burden, the relationship between imaging pathology and burden, irrespective of diagnosis, is unknown. This study investigated the relationship between caregiver burden and patient regional cerebral blood flow in dementia. METHODS: Seventy-sev en patients with cognitive impairment undergoing brain perfusion single-photon emission computed tomography imaging in normal clinical care and their caregivers were recruited. Caregiver burden was ranked from "little" to "severe" using the Zarit Burden Interview and perfusion values extracted from the patient images for predefined regions of interest. The associations between burden score and regional function on imaging were tested. RESULTS: Burden score was significantly higher for caregivers of patients with abnormal perfusion compared to those with normal perfusion in the left and right frontal, right parietal, and right temporal lobes. No difference in burden was found in the left parietal or temporal groups. Correlations showed that a higher caregiver burden was associated with lower patient perfusion scores in the same regions. CONCLUSION: Caregiver burden is strongly related to the extent of frontal or right-predominant parietal or temporal lobe dysfunction. Regional abnormality on perfusion imaging can be used to facilitate identification of individuals who are likely to create a high burden on caregivers.

Occipital lobe and posterior cingulate perfusion in the prediction of dementia with Lewy body pathology in a clinical sample.

OBJECTIVE: The aim of this study was to investigate the diagnostic value of occipital lobe and posterior cingulate perfusion in predicting dopamine transporter imaging outcome using a quantitative measure of analysis. PATIENTS AND METHODS: In total, 99 patients with cognitive complaints who had undergone both technetium-99m-hexamethylpropyleneamine oxime single-photon emission computed tomography (Tc-HMPAO SPECT) and I ioflupane (I-FP-CIT also called DaTSCAN) imaging in a dementia diagnostic center were analyzed. Measures of perfusion were calculated from HMPAO SPECT images for the medial and lateral occipital lobe, the posterior cingulate cortex, precuneus and cuneus regions of interest using statistical parametric mapping 8. DaTSCAN images were quantified and specific binding ratios were calculated independent from HMPAO SPECT results. Statistical parametric mapping and tests of associations between perfusion and I-FP-CIT imaging were completed. RESULTS: Regions of interest on HMPAO yielded poor predictive values when used independently to predict I-FP-CIT status; however, the combination of normal posterior cingulate perfusion with medial and lateral occipital hypoperfusion was associated significantly with I-FP-CIT status, χ (1, N=99)=9.72, P=0.002. This combination also yielded a high positive likelihood ratio and specificity (11.1, 98%). Sensitivity was, however, low (22%). No significant perfusion differences were found when abnormal and normal I-FP-CIT groups were compared directly using voxel-based morphometry (P<0.05, family-wise error). CONCLUSION: The combination of medial and lateral occipital hypoperfusion with preserved posterior cingulate gyrus perfusion is highly specific for individuals with a positive I-FP-CIT scan in a clinical sample where diagnostic doubt exists. This regional combination, however, lacks sensitivity; therefore, absence of the sign cannot be used to rule out dementia with Lewy bodies. A positive finding provides strong evidence to rule in dementia with Lewy bodies.

Sorption of radiocesium by active silica.

Cement and cement components have previously been shown to exhibit negligible sorption for cesium. Pyrogenic silica has been examined as an additive to cement materials for its ability to reduce the leachability of cesium and to provide a host material with permanent sorption sites. The incorporation of silica into cement composites can also improve the physical characteristics and strength of these materials as long ages. At neutral pH values, there is significant sorption of cesium by silica, but in high pH regimes, such as occur in cement environments, initial sorption is enhanced but this high level of sorption is followed by a gradual release of Cs. This apparent desorption is due to the consumption of SiO2 by Ca(OH)2 to form products which have little sorption potential for cesium. If, however, sufficient SiO2 is added to the system initially such that an excess remains after satisfying the demands of the Ca(OH)2 reaction, permanent sorption sites for cesium may be created.