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Background <p>In preclinical PET/MR, attenuation correction (AC) uses a mix of pre-calculated attenuation maps accounting for animal cradles and organ segmentation obtained from whole-body MR using a volume coil. The development of X-nuclei such as <sup>23</sup>Na or <sup>31</sup>P may benefit from high sensitivity surface coils, which could lead to inaccurate PET quantification. In this study, we evaluated the benefit of a pre-calculated attenuation map including a dedicated cradle enclosing a surface coil for <sup>18</sup>F-FDG PET imaging.</p> Materials and methods <p>We developed a 3D-printed cradle (DC) embedding a 20&#xa0;mm surface coil made of PLA (polylactic acid), coated with a thin cap of epoxy. An attenuation map was generated using computed tomography and integrated into PET reconstruction. To validate AC, we compared PET images to those obtained using a conventional cradle and a volume coil (CC). Various image quality metrics were evaluated in various phantoms including a NEMA NU-4 (recovery coefficients (RC), uniformity (%STD), spillover ratio (SOR)), a homogenous phantom (slice and inter-slice uniformity) and a resolution phantom (spatial resolution). Finally, cardiac <sup>18</sup>F-FDG PET images acquired with the 2 cradles were compared in Sprague-Dawley rats.</p> Results <p>RC obtained using DC and CC configurations were not significantly different. However, the %STD was significantly increased with the DC (5.07 ± 0.18) vs. CC (3.29 ± 0.53, <i>p</i> = 0.0002) leading to a decreased CNR with DC. The SOR was similar between the two cradles. In homogenous phantom, there was a non-significant 1.58% underestimation of the PET signal near the surface coil and 5% overestimation on the opposite side when using the DC vs. CC. Uniformity between slice was significantly higher in DC than in CC (3.15 ± 1.2% for DC vs. 2.24 ± 0.7% for CC, <i>p</i> = 0.02) while uniformity inter-slice was similar in DC and CC (2.25 ± 0.83% for DC vs. 1.93 ± 0.44% for CC, <i>p</i> = 0.2). Spatial resolution was similar between DC and CC (axial: 1.80 vs. 1.63&#xa0;mm, tangential: 1.62 vs. 1.79&#xa0;mm and radial resolution: 1.53 vs. 1.76&#xa0;mm for DC and CC respectively). In-vivo, cardiac standardized uptake values were similar between the two cradles (3.55 ± 0.89 and 3.59 ± 1.02 for DC and CC respectively, <i>p</i> = 0.81).</p> Conclusion <p>Pre-calculated attenuation map using a standardized positioning of MR surface coil provided similar <sup>18</sup>F-FDG PET images compared to a conventional PET/MR system with a volume coil, allowing its usage for combined PET and X-nuclei MR.</p>

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Evaluation of precalculated attenuation correction map for preclinical cardiac PET/MR using a 1H/23Na surface coil

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  • 发表日期：

    2026年1月20日

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  • Hanan Rida,
  • Mona Guetlin,
  • Mikael Naveau,
  • Martin Haas,
  • Alexandre Lebrun,
  • Michael Joubert,
  • Alain Manrique

摘要

Background

In preclinical PET/MR, attenuation correction (AC) uses a mix of pre-calculated attenuation maps accounting for animal cradles and organ segmentation obtained from whole-body MR using a volume coil. The development of X-nuclei such as 23Na or 31P may benefit from high sensitivity surface coils, which could lead to inaccurate PET quantification. In this study, we evaluated the benefit of a pre-calculated attenuation map including a dedicated cradle enclosing a surface coil for 18F-FDG PET imaging.

Materials and methods

We developed a 3D-printed cradle (DC) embedding a 20 mm surface coil made of PLA (polylactic acid), coated with a thin cap of epoxy. An attenuation map was generated using computed tomography and integrated into PET reconstruction. To validate AC, we compared PET images to those obtained using a conventional cradle and a volume coil (CC). Various image quality metrics were evaluated in various phantoms including a NEMA NU-4 (recovery coefficients (RC), uniformity (%STD), spillover ratio (SOR)), a homogenous phantom (slice and inter-slice uniformity) and a resolution phantom (spatial resolution). Finally, cardiac 18F-FDG PET images acquired with the 2 cradles were compared in Sprague-Dawley rats.

Results

RC obtained using DC and CC configurations were not significantly different. However, the %STD was significantly increased with the DC (5.07 ± 0.18) vs. CC (3.29 ± 0.53, p = 0.0002) leading to a decreased CNR with DC. The SOR was similar between the two cradles. In homogenous phantom, there was a non-significant 1.58% underestimation of the PET signal near the surface coil and 5% overestimation on the opposite side when using the DC vs. CC. Uniformity between slice was significantly higher in DC than in CC (3.15 ± 1.2% for DC vs. 2.24 ± 0.7% for CC, p = 0.02) while uniformity inter-slice was similar in DC and CC (2.25 ± 0.83% for DC vs. 1.93 ± 0.44% for CC, p = 0.2). Spatial resolution was similar between DC and CC (axial: 1.80 vs. 1.63 mm, tangential: 1.62 vs. 1.79 mm and radial resolution: 1.53 vs. 1.76 mm for DC and CC respectively). In-vivo, cardiac standardized uptake values were similar between the two cradles (3.55 ± 0.89 and 3.59 ± 1.02 for DC and CC respectively, p = 0.81).

Conclusion

Pre-calculated attenuation map using a standardized positioning of MR surface coil provided similar 18F-FDG PET images compared to a conventional PET/MR system with a volume coil, allowing its usage for combined PET and X-nuclei MR.