MIRD Pamphlet No. 33: MIRDpvc-A Software Tool for Recovery Coefficient-Based Partial-Volume Correction.

Partial-volume effects (PVEs) arise from the limited spatial resolution of PET and SPECT imaging systems, causing the systematic underestimation of activity concentration in structures that may hold critical diagnostic, treatment, or dosimetric information that impacts patient management. Recovery coefficient (RC)-based partial-volume correction (PVC) is one of the simpler approaches used to correct for partial-volume losses impacting image-based activity estimates in quantitative nuclear medicine. Despite its routine application, RC PVC lacks standardization, underscoring the need for a validated and vetted tool to facilitate consistent use across the community. As part of the MIRDsoft community dosimetry tools project, we have developed MIRDpvc-a worksheet that facilitates a resolution-based RC PVC approach that enables shape-specific corrections, alongside conventional RC curve corrections. In this work, we describe the MIRDpvc software and validate the new PVC methodology using various simulated studies. The recovery coefficient equivalent resolution-geometric mean (RECOVER-GM) model implemented in MIRDpvc represents a straightforward and effective improvement in the quantitative accuracy of mean activity concentrations within volumes of interest in PET and SPECT images, accounting for both spill-out and spill-in PVEs and incorporating shape-specific corrections. The simplicity and accessibility of the software make it practical for clinical implementation, providing a significant improvement over methods that rely on spherical assumptions. The RECOVER-GM method incorporates lesion geometry while maintaining computational efficiency, highlighting its practical advantages for PVC in PET and SPECT imaging.