Groen J M, Dijkstra H, Greuter M J W, Oudkerk M
Department of Radiology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, The Netherlands.
Med Phys. 2009 Feb;36(2):438-46. doi: 10.1118/1.3049590.
The purpose of this paper is to investigate calcium scoring on computed tomography (CT) using an adjusted threshold depending on the maximum Hounsfield value within the calcification (HU(peak)). The volume of 19 calcifications was retrospectively determined on 64-slice multidetector CT and dual source CT (DSCT) at different thresholds and the threshold associated with the physical volume was determined. In addition, approximately 10 000 computer simulations were done simulating the same process for calcifications with mixed density. Using these data a relation between the HU(peak) and the threshold could be established. Hereafter, this relation was assessed by scanning six calcifications in a phantom at 40-110 beats per minute using DSCT. The influence of motion was determined and the measured calcium scores were compared to the physical volumes and mass. A positive linear correlation was found between the scoring threshold and the HU(peak) of the calcifications both for the phantom measurements as for the computer simulations. Using this relation the individual threshold for each calcification could be calculated. Calcium scores of the moving calcifications determined with an adjusted threshold were approximately 30% less susceptible to cardiac motion compared to standard calcium scoring. Furthermore, these scores approximated the physical volume and mass at least 10% better than the standard calcium scores. The threshold in calcium scoring should be adjusted for each individual calcification based on the HU(peak) of the calcification. Calcium scoring using an adjusted threshold is less susceptible to cardiac motion and more accurate compared to the physical values.
本文的目的是研究在计算机断层扫描（CT）上进行钙化评分时，根据钙化灶内最大亨氏值（HU(peak)）调整阈值的方法。回顾性测定了19个钙化灶在64层多排CT和双源CT（DSCT）上不同阈值下的体积，并确定了与实际体积相关的阈值。此外，对密度混合的钙化灶进行了约10000次计算机模拟，模拟相同的过程。利用这些数据建立了HU(peak)与阈值之间的关系。此后，使用DSCT以每分钟40 - 110次心跳的速度对模型中的六个钙化灶进行扫描，评估这种关系。确定了运动的影响，并将测量的钙化评分与实际体积和质量进行比较。对于模型测量和计算机模拟，均发现评分阈值与钙化灶的HU(peak)之间存在正线性相关。利用这种关系可以计算每个钙化灶的个体阈值。与标准钙化评分相比，使用调整阈值确定的运动钙化灶的钙评分对心脏运动的敏感性降低约30%。此外，这些评分与实际体积和质量的近似程度比标准钙评分至少高10%。钙化评分的阈值应根据钙化灶的HU(peak)对每个个体钙化灶进行调整。与实际值相比，使用调整阈值的钙化评分对心脏运动的敏感性较低且更准确。
