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Aim/introduction <p>Quantitative <sup>177</sup>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 <sup>177</sup>Lu-SPECT based tumor dosimetry.</p> Materials/methods <p>The NEMA IEC Body Phantom (foreground-to-background ratio 8:1, 237:30&#xa0;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&#xa0;h post-injection) of 20 patients who received either [<sup>177</sup>Lu]Lu-DOTA-TATE (<i>n</i> = 10) or [<sup>177</sup>Lu]Lu-PSMA-I&amp;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.</p> Results <p>A sigma of 6.0&#xa0;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 ([<sup>177</sup>Lu]Lu-DOTA-TATE: <i>n</i> = 42) ([<sup>177</sup>Lu]Lu-PSMA-I&amp;T: y = 56). For OR + LRD and OR + RC an average increase of 22 ± 12% and 57 ± 36% of tumor AD was found.</p> Conclusion <p>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 <sup>177</sup>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.</p> Graphical Abstract <p></p>

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

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月13日

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  • Zachary Ells,
  • Grigory Liubchenko,
  • Mikhail Rumiantcev,
  • Maximilian Scheifele,
  • Angelica Noto,
  • Sophie C. Siegmund,
  • Sandra Resch,
  • Andreas Harbach,
  • Rudolf A. Werner,
  • Matthias Brendel,
  • Gabriel Sheikh,
  • Mathias Zacherl,
  • Guido Böning,
  • Lena M. Unterrainer,
  • Sibylle I. Ziegler,
  • Astrid Delker

摘要

Aim/introduction

Quantitative 177Lu-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 177Lu-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 [177Lu]Lu-DOTA-TATE (n = 10) or [177Lu]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 ([177Lu]Lu-DOTA-TATE: n = 42) ([177Lu]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 177Lu-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.

Graphical Abstract