Publications (2)2.66 Total impact
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ABSTRACT: Soft tissue attenuation artefacts are more likely to occur in patients with high body mass index (BMI) undergoing myocardial perfusion imaging (MPI) and therefore it is routine practice in our department to perform attenuation correction in this group of patients. However, we suspected that attenuation artefacts may also occur in patients with normal BMI. We collected data prospectively on 57 patients with BMI less than 25kg/m(2) who underwent stress-rest MPI single photon emission tomography (SPET) as part of their standard management at our institution. The differences between the attenuation corrected (AC) and non attenuation corrected (NC) images were evaluated by two experienced readers blinded to patient gender and clinical details. Visual improvement in perfusion with attenuation correction was seen in 54.4% of patients with normal BMI and was more common in males (84.2%) than females (39.5%). Discordances between AC and NC were most frequent in the inferior, inferolateral and anteroseptal segments in both males and females and were also seen in the apical and anterior segments in some patients, mainly in females, in keeping with the well-recognized distribution pattern for attenuation artefacts. In conclusion, although a small sample size was used in this study, changes in appearance with attenuation correction likely to represent attenuation artefacts were seen in 54.4% of patients with normal BMI and were two times more common in males than females. These changes were felt to be clinically relevant in that they could lead to a change in the final report and may ultimately affect the diagnosis and clinical management. Thus, attenuation correction could be of value in patients of normal BMI. Further larger studies with correlation with clinical follow-up or invasive coronary angiography are warranted.
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ABSTRACT: High count rate positron emission tomography (PET) systems offer the potential for accurate myocardial blood flow (MBF) quantification during first-pass dynamic imaging in conjunction with standard rubidium-82 (Rb-82) PET myocardial perfusion imaging (MPI). We investigate the feasibility of this using a Siemens Biograph mCT. Current routine clinical PET MPI is performed with 1480 MBq (40 mCi) Rb-82. Dynamic first-pass images from 217 consecutive patients were reviewed for evidence of detector saturation, indicating that count rate limits had been exceeded. Phantom acquisitions in the presence of high count rates were performed to assess the effect of detector saturation on quantitative accuracy. Accurate MBF quantification and perfusion imaging using current protocols was successful in 85% of clinical cases. Detector block saturation was observed in 15% of cases, and phantom acquisitions indicate that saturation may have an adverse effect on quantitative accuracy. Visualization of transit or pooling of Rb-82 in the vessels in the axilla was the most consistent feature when saturation occurred. Reduction of administered activity to 1110 MBq (30 mCi) and subsequent evaluation of 159 patients ensured successful MBF quantification while maintaining good diagnostic quality perfusion imaging in 99% of cases. MBF quantification and good-quality standard perfusion imaging can be performed on a high count rate PET system using a single-acquisition protocol. The administered activity requires optimization and we recommend 1110 MBq for PET MPI with a Biograph mCT.
Central Manchester University Hospitals NHS Foundation TrustManchester, England, United Kingdom