Black Dale, Xiao Xingshuo, Molloi Sabee
University of California, Irvine, Department of Radiological Sciences, Irvine, California, United States.
J Med Imaging (Bellingham). 2023 Jul;10(4):043502. doi: 10.1117/1.JMI.10.4.043502. Epub 2023 Jul 10.
Agatston scoring does not detect all the calcium present in computed tomography scans of the heart. A technique that removes the need for thresholding and quantifies calcium mass more accurately and reproducibly is needed.
Integrated intensity and volume fraction techniques were evaluated for accurate quantification of calcium mass. Integrated intensity calcium mass, volume fraction calcium mass, Agatston scoring, and spatially weighted calcium scoring were compared with known calcium mass in simulated and physical phantoms. The simulation was created to match a 320-slice CT scanner. Fat rings were added to the simulated phantoms, which resulted in small (), medium (), and large () phantoms. Three calcification inserts of different diameters and hydroxyapatite densities were placed within the phantoms. All the calcium mass measurements were repeated across different beam energies, patient sizes, insert sizes, and densities. Physical phantom images from a previously reported study were then used to evaluate the accuracy and reproducibility of the techniques.
Both integrated intensity calcium mass and volume fraction calcium mass yielded lower root mean squared error (RMSE) and deviation (RMSD) values than Agatston scoring in all the measurements in the simulated phantoms. Specifically, integrated calcium mass (RMSE: 0.49 mg, RMSD: 0.49 mg) and volume fraction calcium mass (RMSE: 0.58 mg, RMSD: 0.57 mg) were more accurate for the low-density stationary calcium measurements than Agatston scoring (RMSE: 3.70 mg, RMSD: 2.30 mg). Similarly, integrated calcium mass (15.74%) and volume fraction calcium mass (20.37%) had fewer false-negative (CAC = 0) measurements than Agatston scoring (75.00%) and spatially weighted calcium scoring (26.85%), on the low-density stationary calcium measurements.
The integrated calcium mass and volume fraction calcium mass techniques can potentially improve risk stratification for patients undergoing calcium scoring and further improve risk assessment compared with Agatston scoring.
阿加斯顿评分法无法检测出心脏计算机断层扫描中存在的所有钙。需要一种无需阈值设定且能更准确、可重复地量化钙质量的技术。
对积分强度和体积分数技术进行评估，以准确量化钙质量。将积分强度钙质量、体积分数钙质量、阿加斯顿评分和空间加权钙评分与模拟和物理模型中已知的钙质量进行比较。创建模拟以匹配320层CT扫描仪。在模拟模型中添加脂肪环，从而得到小、中、大三种模型。在模型中放置三个不同直径和羟基磷灰石密度的钙化插入物。在不同的束能量、患者体型、插入物尺寸和密度下重复所有钙质量测量。然后使用先前报道研究中的物理模型图像来评估这些技术的准确性和可重复性。
在模拟模型的所有测量中，积分强度钙质量和体积分数钙质量产生的均方根误差（RMSE）和偏差（RMSD）值均低于阿加斯顿评分。具体而言，对于低密度固定钙测量，积分钙质量（RMSE：0.49毫克，RMSD：0.49毫克）和体积分数钙质量（RMSE：0.58毫克，RMSD：0.57毫克）比阿加斯顿评分（RMSE：3.70毫克，RMSD：2.30毫克）更准确。同样，在低密度固定钙测量中，积分钙质量（15.74%）和体积分数钙质量（20.37%）的假阴性（CAC = 0）测量比阿加斯顿评分（75.00%）和空间加权钙评分（26.85%）更少。
与阿加斯顿评分相比，积分钙质量和体积分数钙质量技术可能会改善接受钙评分患者的风险分层，并进一步改善风险评估。
