PET Attenuation Map Generation from Virtual Monochromatic Images Obtained with Photon Counting CT Scanners

Abstract

Attenuation correction (AC) is essential for achieving artefact-free PET/MR images. Many previous studies have primarily relied on conventional CT scanners for AC. Currently, CT-derived PET attenuation maps are based on conversion schemes from conventional CT scanners with data from polyenergetic X-ray spectra and it is known that converting from these CT image data to monoenergetic 511 keV attenuation coefficients unavoidably introduces systematic errors in the attenuation coefficients employed for AC in PET imaging. To address this issue, we utilized spectral CT in order to obtain more accurate attenuation maps. Spectral CT offers advantages over conventional CT scanners by providing the possibility of material decomposition. Spectral CT systems also allow to reconstruct virtual monochromatic images (VMI) from the inherently multiple polyenergetic data sets of CT. VMIs can be used to obtain virtual non-contrast (VNC) images and bone mineral density measurements. In our approach, we plan to use angiographic spectral CT scans with an administration of iodinated contrast agents and to compute VNC images from the obtained dataset. The conversion scheme from monochromatic CT images to linear attenuation coefficients at 511 keV was obtained by acquiring spectral CT data for different tissue types using an electron density phantom developed for spectral CTs and a photon counting (PC) CT scanner.

Authors 7

1. Heba Alrakh

   Forschungszentrum Jülich

   Affiliation as printed

   Forschungszentrum Jülich, Institute of Neuroscience and Medicine - 4,Jülich,North Rhine-Westphalia,Germany

2. Lutz Tellmann

   Forschungszentrum Jülich

   Affiliation as printed

   Forschungszentrum Jülich, Institute of Neuroscience and Medicine - 4,Jülich,North Rhine-Westphalia,Germany

3. Omid Nikoubashman Aachen Department of Diagnostic and Interventional Neuroradiology

   RWTH Aachen University

   Affiliation as printed

   RWTH University Aachen,Department of Diagnostic and Interventional Neuroradiology,Aachen,North Rhine-Westphalia,Germany

4. Sebastian Faby

   Siemens Healthineers (Germany)

   Affiliation as printed

   Siemens Healthineers AG,Department of Computed Tomography,Forchheim,Bavaria,Germany

5. Ali Abu Arra

   An-Najah National University

   Affiliation as printed

   An-Najah National University,Department of Medical Imaging,Nablus,State of Palestine

6. Nadim Jon Shah

   Forschungszentrum Jülich

   Affiliation as printed

   Forschungszentrum Jülich, Institute of Neuroscience and Medicine - 4,Jülich,North Rhine-Westphalia,Germany

7. Christoph W. Lerche

   Forschungszentrum Jülich

   Affiliation as printed

   Forschungszentrum Jülich, Institute of Neuroscience and Medicine - 4,Jülich,North Rhine-Westphalia,Germany