Investigation of iterative deconvolution in 177Lu-SPECT imaging for lesion dosimetry

Ells, Zachary; Liubchenko, Grigory; Rumiantcev, Mikhail; Scheifele, Maximilian; Noto, Angelica; Siegmund, Sophie C.; Resch, Sandra; Harbach, Andreas; Werner, Rudolf A.; Brendel, Matthias; Sheikh, Gabriel; Zacherl, Mathias; Böning, Guido; Unterrainer, Lena M.; Ziegler, Sibylle I.; Delker, Astrid (2026): Investigation of iterative deconvolution in 177Lu-SPECT imaging for lesion dosimetry. EJNMMI Physics, 13: 34. ISSN 2197-7364

Abstract

Aim/introduction

Quantitative 177 Lu-SPECT allows for patient specific dosimetry, but due to the limited spatial resolution absorbed doses (AD) can be underestimated. Implementation of the Lucy-Richardson deconvolution (LRD) algorithm for spill-over correction in PET has been investigated. Therefore, the aim of this study was to extend the potential application of LRD to 177 Lu-SPECT based tumor dosimetry.

Materials/methods

The NEMA IEC Body Phantom (foreground-to-background ratio 8:1, 237:30 kBq/mL) was measured according to the local imaging and reconstruction protocol. The two main parameters of LRD, sigma and number of iterations, were determined in two steps. First, a matched filter resolution analysis was conducted on the ground truth activity distribution as segmented from the NEMA IEC Body Phantom data to define the sigma of a 3D Gaussian point-spread-function, which describes the system’s spatial resolution. Secondly, using this sigma, a suitable number of LRD iterations was determined by comparing sphere recovery coefficients (RC) and signal-to-noise ratios. The selected parameters were then applied to the reconstructed SPECT series (24, 48, and 72 h post-injection) of 20 patients who received either [ 177 Lu]Lu-DOTA-TATE ( n = 10) or [ 177 Lu]Lu-PSMA-I&T (y = 10) treatment, in order to evaluate its impact on AD estimates. Lesion AD from the original reconstruction (OR) and OR + LRD were estimated using MIM SurePlan™ MRT. The AD from OR, OR + LRD, and OR + RC (phantom-based recovery correction based on volume) were compared.

Results

A sigma of 6.0 mm and four iterations resulted in an average improvement of 18.9 ± 4.7% and 17.4 ± 7.6% in the sphere recovery coefficients and the signal to noise ratio, respectively. In total, 98 lesions were evaluated ([ 177 Lu]Lu-DOTA-TATE: n = 42) ([ 177 Lu]Lu-PSMA-I&T: y = 56). For OR + LRD and OR + RC an average increase of 22 ± 12% and 57 ± 36% of tumor AD was found.

Conclusion

OR + LRD increased AD compared to OR, independent of administered radiopharmaceutical and lesion location. This study suggests that implementing LRD may be a promising option for image-based spill-over correction in 177 Lu-SPECT based dosimetry. Further studies are necessary to investigate the effect of different PVC methods, such as LRD or phantom-based correction factors, on overall uncertainty of lesion ADs.

• Dokumententyp: Artikel (Klinikum der LMU)
• Organisationseinheit (Fakultäten): 07 Medizin > Klinikum der LMU München > Klinik und Poliklinik für Nuklearmedizin
• DFG-Fachsystematik der Wissenschaftsbereiche: Lebenswissenschaften
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 390857198
• DFG: Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892