caliPER: A software for blood-free parametric Patlak mapping using PET/MRI input function
Praveen Dassanayake,
Lumeng Cui,
Elizabeth Finger,
Matthew Kewin,
Jennifer Hadaway,
Andrea Soddu,
Bjoern Jakoby,
Sven Zuehlsdorf,
Keith S St Lawrence,
Gerald Moran,
Udunna C Anazodo
Affiliations
Praveen Dassanayake
Lawson Health Research Institute, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada
Lumeng Cui
Division of Biomedical Engineering, University of Saskatchewan, Saskatoon, Canada; Siemens Healthineers, Oakville, Mississauga, Ontario, Canada
Elizabeth Finger
Lawson Health Research Institute, London, Ontario, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
Matthew Kewin
Department of Medical Biophysics, Western University, London, Ontario, Canada
Jennifer Hadaway
Lawson Health Research Institute, London, Ontario, Canada
Andrea Soddu
Department of Physics and Astronomy, Western University, London, Ontario, Canada
Lawson Health Research Institute, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada; Corresponding author at: Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street Rm WB317, Montreal, Quebec H3A2B4, Canada.
Routine clinical use of absolute PET quantification techniques is limited by the need for serial arterial blood sampling for input function and more importantly by the lack of automated pharmacokinetic analysis tools that can be readily implemented in clinic with minimal effort. PET/MRI provides the ability for absolute quantification of PET probes without the need for serial arterial blood sampling using image-derived input functions (IDIFs). Here we introduce caliPER, a modular and scalable software for simplified pharmacokinetic modeling of PET probes with irreversible uptake or binding based on PET/MR IDIFs and Patlak Plot analysis. caliPER generates regional values or parametric maps of net influx rate (Ki) using reconstructed dynamic PET images and anatomical MRI aligned to PET for IDIF vessel delineation. We evaluated the performance of caliPER for blood-free region-based and pixel-wise Patlak analyses of [18F] FDG by comparing caliPER IDIF to serial arterial blood input functions and its application in imaging brain glucose hypometabolism in Frontotemporal dementia. IDIFs corrected for partial volume errors including spill-out and spill-in effects were similar to arterial blood input functions with a general bias of around 6–8%, even for arteries <5 mm. The Ki and cerebral metabolic rate of glucose estimated using caliPER IDIF were similar to estimates using arterial blood sampling (<2%) and within limits of whole brain values reported in literature. Overall, caliPER is a promising tool for irreversible PET tracer quantification and can simplify the ability to perform parametric analysis in clinical settings without the need for blood sampling.
