Computed Tomography Attenuation Correction and Prone Imaging: Methods to Eliminate Soft Tissue Artefacts in Myocardial Perfusion Imaging
BACKGROUND: Attenuation artefact remains a distressing cause of impaired specificity in obese patients undergoing myocardial imaging (MPI). Prone imaging, while valuable in correcting the problem, is not tolerated in all patients.
This study was designed to assess the effect of CT attenuation correction on reporting certainty in obese patients, and comparing this to prone imaging, the current standard for assessing attenuation artefacts on MPI in our department.
METHODS and RESULTS: 30 patients with a BMI > 30 referred for routine single day myocardial perfusion imaging underwent additional low dose cardiac CT imaging (using a Phillips precedence camera and Astonish software) at rest and post stress, in addition to routine supine and prone MPI. The supine cardiac images were CT attenuation corrected (CTAC). The studies were reported by 2 experienced reporters blinded to the clinical and angiographic findings. Both the CTAC and the prone images were reported in conjunction with the supine images. The scans were reported as ‘definitely normal’, probably normal, probably abnormal and definitely abnormal. Summed stress and difference scores were derived quantitatively using QGS software. Image quality was also annotated. 10/30 patients underwent cardiac catheterisation within 3 months of the MPI. Reporting of all studies and final statistical analysis of results is still underway.
CONCLUSION: CT attenuation correction of MPI may improve reporting certainty. This study assesses the value of this new modality in obese patients compared to standard supine and prone imaging undertaken in our department.