Department of Mechanical and Manufacturing Engineering.
Department of Electrical and Software Engineering, University of Calgary, Calgary, Alberta.
Invest Radiol. 2022 Sep 1;57(9):613-619. doi: 10.1097/RLI.0000000000000879. Epub 2022 Apr 21.
The aim of this study was to assess the accuracy and precision of a novel application of 3-material decomposition (3MD) with virtual monochromatic images (VMIs) in the dual-energy computed tomography (DECT) assessment of monosodium urate (MSU) and hydroxyapatite (HA) phantoms compared with a commercial 2-material decomposition (2MD) and dual-thresholding (DT) material decomposition methods.
Monosodium urate (0.0, 3.4, 13.3, 28.3, and 65.2 mg/dL tubes) and HA (100, 400, and 800 mg/cm 3 tubes) phantoms were DECT scanned individually and together in the presence of the foot and ankle of 15 subjects. The raw data were decomposed with 3MD-VMI, 2MD, and DT to produce MSU-only and HA-only images. Mean values of 10 × 10 × 10-voxel volumes of interest (244 μm 3 ) placed in each MSU and HA phantom well were obtained and compared with their known concentrations and across measurements with subjects' extremities to obtain accuracy and precision measures. A statistical difference was considered significant if P < 0.05.
Compared with known phantom standards, 3MD-VMI was accurate for the detection of MSU concentrations as low as 3.4 mg/dL ( P = 0.75). In comparison, 2MD was limited to 13.3 mg/dL ( P = 0.06) and DT was unable to detect MSU concentrations below 65.2 mg/L ( P = 0.16). For the HA phantom, 3MD-VMI and 2MD were accurate for all concentrations including the lowest at 100 mg/cm 3 ( P = 0.63 and P = 0.55, respectively). Dual-thresholding was not useful for the decomposition of HA phantom. Precision was high for both 3MD-VMI and 2MD measurements for both MSU and HA phantoms. Qualitatively, 3MD-VMI MSU-only images demonstrated reduced beam-hardening artifact and voxel misclassification, compared with 2MD and DT.
Three-material decomposition-VMI DECT is accurate for quantification of MSU and HA concentrations in phantoms and accurately detects a lower concentration of MSU than either 2MD or DT. For concentration measurements of both MSU and HA phantoms, 3MD-VMI and 2MD have high precision, but DT had limitations. Clinical implementation of 3MD-VMI DECT promises to improve the performance of this imaging modality for diagnosis and treatment monitoring of gout.
本研究旨在评估一种新的三物质分解（3MD）应用的准确性和精密度，该方法使用虚拟单能量图像（VMIs）在双能 CT（DECT）评估单钠尿酸盐（MSU）和羟磷灰石（HA）时，与商业的二物质分解（2MD）和双阈值（DT）物质分解方法进行比较。
单独和共同对 0.0、3.4、13.3、28.3 和 65.2mg/dL 管的 MSU 以及 100、400 和 800mg/cm 3 管的 HA 尿酸盐和 HA 幻影进行 DECT 扫描。用 3MD-VMI、2MD 和 DT 对原始数据进行分解，产生 MSU 仅和 HA 仅图像。从每个 MSU 和 HA 幻影井的 10×10×10 体素感兴趣区（244μm 3 ）获得 10 个平均值，并与已知浓度进行比较，并与受检者四肢的测量结果进行比较，以获得准确性和精密度测量值。如果 P<0.05，则认为统计学差异显著。
与已知的幻影标准相比，3MD-VMI 对检测低至 3.4mg/dL 的 MSU 浓度是准确的（P=0.75）。相比之下，2MD 的检测能力仅限于 13.3mg/dL（P=0.06），而 DT 无法检测低于 65.2mg/L 的 MSU 浓度（P=0.16）。对于 HA 幻影，3MD-VMI 和 2MD 对所有浓度均准确，包括最低的 100mg/cm 3 （P=0.63 和 P=0.55）。DT 对 HA 幻影的分解没有用。对于 MSU 和 HA 幻影，3MD-VMI 和 2MD 测量的精密度均很高。定性地，3MD-VMI 的 MSU 仅图像与 2MD 和 DT 相比，显示出降低的束硬化伪影和体素分类错误。
三物质分解-VMI DECT 可准确量化尿酸盐和 HA 浓度，并且比 2MD 或 DT 更准确地检测到较低的 MSU 浓度。对于 MSU 和 HA 幻影的浓度测量，3MD-VMI 和 2MD 具有高精度，但 DT 具有局限性。3MD-VMI DECT 的临床应用有望提高该成像方式对痛风诊断和治疗监测的性能。
