Sydney Vital Research Scholar Awardee Harry Marquis was the primary author of a recently published paper investigating a novel approach to SPECT image reconstruction.
Mr Marquis worked with Sydney Vital director Prof Dale Bailey, Sydney Vital awardees Dr Yaser Gholami and Takanori Hioki and other researchers from the UK and Australia on the paper titled “Theranostic SPECT reconstruction for improved resolution: application to radionuclide therapy dosimetry,” which was published in EJNMMI Physics.
Mr Marquis says that his team has “developed a new method to produce images of the body from a conventional imaging device called a “SPECT camera” that gives much higher detail and definition than previously possible. The method uses the much improved quality of a PET image of the same subject, used mostly for cancer imaging, to “guide” the poorer quality SPECT image formation process and vastly improve it.”
According to Mr Marquis, this is necessary to improve treatment accuracy: “We need to do this to better understand how to treat patients with the most accurate radiation treatment planning.”
While combining two different scan techniques to improve image quality is not a new idea in itself – “it has been done with CT scans and MRI scans before,” Mr Marquis says – the idea of using the PET image to guide the SPECT is totally novel. “We call this approach a “SPECTRE” image reconstruction.”
As the researchers explain in the conclusion of the paper, “[t]his novel approach to SPECT image reconstruction, using matched pairs of diagnostic (PET) and therapeutic (SPECT) imaging, is a promising method for improving SPECT image quality and thus our ability to accurately monitor treatment,” which in turn allows them to dosage more accurately to treat small targets in the body.
Image: Transverse centre slice of IEC image quality phantom for each reconstruction method. a CT image (segmented spheres), b 68Ga PET, TOF + RM + 5 mm Gaussian, resampled to SPECT dimensions and used as prior image used in the SPECTRE reconstruction. c Our in-house routine qSPECT-OSEM reconstruction (4 iterations and 8 subsets), d OSEM + RM reconstruction (5 iterations and 12 subsets), e OSEM + RM reconstruction (40 iterations and 12 subsets), and f SPECTRE with RM [HKEM parameters: σp = 2, σs = 2, σdp = 5, σds = 5, NN = 5] (40 iterations and 12 subsets). Figure 1, Marquis, H., Deidda, D., Gillman, A. et al. Theranostic SPECT reconstruction for improved resolution: application to radionuclide therapy dosimetry. EJNMMI Phys 8, 16 (2021). doi: 10.1186/s40658-021-00362-x.