可吸收下腔静脉(IVC)过滤器需要嵌入对比度,以进行图像引导的放置和完整性监测。我们计算了校正因子,以解释薄纳米粒子(NP)嵌入材料的部分体积平均,考虑对象和切片厚度,背景信号,和纳米粒子浓度。我们使用包含嵌入铋(Bi)或镱(Yb)的聚己内酯圆盘的体模:0.4-至1.2毫米厚的20mg/mLNPs的圆盘(厚度体模),2mg/mL碘(浓度模型)中0-20mg/mLNPs的0.4mm厚圆盘,和20毫克/毫升NPs在0-10毫克/毫升碘0.4毫米厚的圆盘(背景模型)。在双源CT上以80、90、100和150kVp进行扫描,并进行锡过滤,并以1.0至1.5mm的切片厚度以0.1mm的间隔进行重建。扫描后,处理圆盘用于电感耦合等离子体发射光谱法(ICP-OES)以确定NP浓度。对于每个kVp,在0.5cm2面积上测量所有圆盘的平均和最大CT数(HU)。使用先前测量的校准将HU转化为浓度。通过减去残余切片背景并将磁盘厚度外推到标称和测量的切片灵敏度曲线(SSP),对浓度测量值进行了部分体积平均校正。通过用ICP-OES测量代替CT衍生的浓度并求解厚度来计算一致的切片厚度(STTA)。切片厚度校正因子改善了所有测量数据与ICP-OES的一致性。Yb校正导致浓度体模中的STTA低于Bi校正(1.01对1.31STTA/SSP,其中1.0是完美的协议),不同厚度的体模(1.30比1.87STTA/SSP),背景碘浓度变化的体模中的比率相似(1.34vs1.35STTA/SSP)。所有测得的浓度与ICP-OES密切相关,所有部分体积平均校正与ICP-OES浓度的一致性增加,证明了用CT监测薄IVC可吸收过滤器完整性的潜力。
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Resorbable inferior vena cava (IVC) filters require embedded contrast for image-guided placement and integrity monitoring. We calculated correction factors to account for partial volume averaging of thin nanoparticle (NP)-embedded materials, accounting for object and slice thicknesses, background signal, and nanoparticle concentration. We used phantoms containing polycaprolactone disks embedded with bismuth (Bi) or
ytterbium (Yb): 0.4- to 1.2-mm-thick disks of 20 mg ml-1NPs (thickness phantom), 0.4-mm-thick disks of 0-20 mg ml-1NPs in 2 mg ml-1iodine (concentration phantom), and 20 mg ml-1NPs in 0.4-mm-thick disks in 0-10 mg ml-1iodine (background phantom). Phantoms were scanned on a dual-source CT with 80, 90, 100, and 150 kVp with tin filtration and reconstructed at 1.0- to 1.5-mm slice thickness with a 0.1-mm interval. Following scanning, disks were processed for inductively coupled plasma optical emission spectrometry (ICP-OES) to determine NP concentration. Mean and maximum CT numbers (HU) of all disks were measured over a 0.5-cm2area for each kVp. HU was converted to concentration using previously measured calibrations. Concentration measurements were corrected for partial volume averaging by subtracting residual slice background and extrapolating disk thickness to both nominal and measured slice sensitivity profiles (SSP, mm). Slice thickness to agreement (STTA, mm) was calculated by replacing the CT-derived concentrations with ICP-OES measurements and solving for thickness. Slice thickness correction factors improved agreement with ICP-OES for all measured data. Yb corrections resulted in lower STTA than Bi corrections in the concentration phantom (1.01 versus 1.31 STTA/SSP, where 1.0 is perfect agreement), phantoms with varying thickness (1.30 versus 1.87 STTA/SSP), and similar ratio in phantoms with varying background iodine concentration (1.34 versus 1.35 STTA/SSP). All measured concentrations correlated strongly with ICP-OES and all corrections for partial volume averaging increased agreement with ICP-OES concentration, demonstrating potential for monitoring the integrity of thin IVC resorbable filters with CT.