Shunhavanich Picha, Ferrero Andrea, McCollough Cynthia H, Hsieh Scott S
Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Rd, Pathum Wan, Bangkok 10330, TH (P.S.); Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (P.S., A.F., C.H.M., S.S.H.).
Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 (P.S., A.F., C.H.M., S.S.H.).
Acad Radiol. 2025 Apr;32(4):2064-2072. doi: 10.1016/j.acra.2024.10.025. Epub 2024 Nov 4.
Classification of non-uric acid (NUA) renal stones in dual-energy CT (DECT) is difficult due to their similar CT number ratios (CTRs) and because the CTRs change with patient size and acquisition protocol. In this work, we developed a generalizable framework to estimate correct CTR threshold for different stone types, protocols, and patient sizes and validated the results on two DECT scanners.
Our framework assumes generic x-ray spectra, estimates the added filtration to match half-value-layer (HVL) measurements, and predicts the CTR of each stone type from the chemical composition and patient size. The framework was validated for four calcium or iodine inserts in two solid water phantom sizes on two DECT scanners, and on 45 human urinary stones of five types (uric acid, cystine, calcium oxalate monohydrate, brushite, and hydroxyapatite) in three different water phantom sizes on a dual-source DECT. All scans were performed at high dose, using routine acquisition parameters. The predicted CTR was compared with the measured CTR.
The predicted CTRs for different stone types were consistent with experimentally measured values, with average absolute errors of 2.8% (range 1.3-4.3%), 1.8% (range 0.7-4.4%), and 1.8% (range 0.8-2.4%) for the 30, 40, and 50 cm phantom sizes. The predicted CTR errors of the four inserts were within 6.4%.
The developed framework uses easily obtained HVL measurements to predict renal stone CTRs of different compositions for varied patient sizes. With further refinement, it may help classify NUA subtypes in clinical scans.
在双能CT（DECT）中，非尿酸（NUA）肾结石的分类较为困难，这是因为它们的CT值比率（CTR）相似，且CTR会随患者体型和扫描协议而变化。在本研究中，我们开发了一个通用框架，用于估计不同结石类型、协议和患者体型下的正确CTR阈值，并在两台DECT扫描仪上验证了结果。
我们的框架假设了通用的X射线光谱，估计了附加滤过以匹配半值层（HVL）测量值，并根据化学成分和患者体型预测每种结石类型的CTR。该框架在两台DECT扫描仪上针对两种固体水模尺寸中的四种钙或碘插入物进行了验证，并在双源DECT上针对三种不同水模尺寸中的45颗五种类型（尿酸、胱氨酸、一水草酸钙、透钙磷石和羟基磷灰石）的人体尿路结石进行了验证。所有扫描均使用常规采集参数在高剂量下进行。将预测的CTR与测量的CTR进行比较。
不同结石类型的预测CTR与实验测量值一致，对于30、40和50厘米的模体尺寸，平均绝对误差分别为2.8%（范围1.3 - 4.3%）、1.8%（范围0.7 - 4.4%）和1.8%（范围0.8 - 2.4%）。四种插入物的预测CTR误差在6.4%以内。
所开发的框架利用易于获得的HVL测量值来预测不同成分的肾结石CTR，适用于不同的患者体型。经过进一步完善，它可能有助于在临床扫描中对NUA亚型进行分类。
