衰减图精度对衰减校正微单光子发射计算机断层成像的影响。

Effects of attenuation map accuracy on attenuation-corrected micro-SPECT images.

机构信息

Section Radiation, Detection & Medical Imaging, Delft University of Technology, Mekelweg 15, Delft, 2629 JB, the Netherlands.

出版信息

EJNMMI Res. 2013 Jan 31;3(1):7. doi: 10.1186/2191-219X-3-7.

DOI:10.1186/2191-219X-3-7

PMID:23369630

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC3579699/

Abstract

BACKGROUND

In single-photon emission computed tomography (SPECT), attenuation of photon flux in tissue affects quantitative accuracy of reconstructed images. Attenuation maps derived from X-ray computed tomography (CT) can be employed for attenuation correction. The attenuation coefficients as well as registration accuracy between SPECT and CT can be influenced by several factors. Here we investigate how such inaccuracies influence micro-SPECT quantification.

METHODS

Effects of (1) misalignments between micro-SPECT and micro-CT through shifts and rotation, (2) globally altered attenuation coefficients and (3) combinations of these were evaluated. Tests were performed with a NEMA NU 4-2008 phantom and with rat cadavers containing sources with known activity.

RESULTS

Changes in measured activities within volumes of interest in phantom images ranged from <1.5% (125I) and <0.6% (201Tl, 99mTc and 111In) for 1-mm shifts to <4.5% (125I) and <1.7% (201Tl, 99mTc and 111In) with large misregistration (3 mm). Changes induced by 15° rotation were smaller than those by 3-mm shifts. By significantly altering attenuation coefficients (±10%), activity changes of <5.2% for 125I and <2.7% for 201Tl, 99mTc and 111In were induced. Similar trends were seen in rat studies.

CONCLUSIONS

While getting sufficient accuracy of attenuation maps in clinical imaging is highly challenging, our results indicate that micro-SPECT quantification is quite robust to various imperfections of attenuation maps.

摘要

背景

在单光子发射计算机断层扫描（SPECT）中，光子通量在组织中的衰减会影响重建图像的定量准确性。可以使用 X 射线计算机断层扫描（CT）得出的衰减图进行衰减校正。SPECT 和 CT 之间的衰减系数以及配准精度会受到多种因素的影响。在这里，我们研究了这些不准确性如何影响微 SPECT 定量。

方法

评估了（1）通过平移和旋转导致的微 SPECT 和微 CT 之间的配准误差，（2）全局改变的衰减系数，以及（3）这两种因素的组合的影响。使用 NEMA NU 4-2008 体模和含有已知放射性活度源的大鼠尸体进行了测试。

结果

在体模图像中感兴趣容积内测量的活性变化范围为 <1.5%（125I）和 <0.6%（201Tl、99mTc 和 111In），对于 1mm 的平移变化<4.5%（125I）和 <1.7%（201Tl、99mTc 和 111In），对于大的配准误差（3mm）。15°旋转引起的变化小于 3mm 平移引起的变化。通过显著改变衰减系数（±10%），可引起 <5.2% 的 125I 活性变化和 <2.7% 的 201Tl、99mTc 和 111In 活性变化。在大鼠研究中也观察到了类似的趋势。