A deformable model for tracking tumors across consecutive imaging studies

Abstract

Objective A deformable registration technique was developed and evaluated to track and quantify tumor response to radiofrequency ablation for patients with liver malignancies. Materials and methods The method uses the combined power of global and local alignment of pre- and post-treatment computed tomography image data sets. The strategy of the algorithm is to infer volumetric deformation based upon surface displacements using a linearly elastic finite element model (FEM). Using this framework, the major challenge for tracking tumor location is not the tissue mechanical properties for FEM modeling but rather the evaluation of boundary conditions. Three different methods were systematically investigated to automatically determine the boundary conditions defined by the correspondences on liver surfaces. Results Using both 2D synthetic phantoms and imaged 3D beef liver data we performed gold standard registration while measuring the accuracy of non-rigid deformation. The fact that the algorithms could support mean displacement error of tumor deformation up to 2 mm indicates that this technique may serve as a useful tool for surgical interventions. The method was further demonstrated and evaluated using consecutive imaging studies for three liver cancer patients. Conclusion The FEM-based surface registration technique provides accurate tracking and monitoring of tumor and surrounding tissue during the course of treatment and follow-up.

Development of MRI phantom equivalent to human tissues for 3.0‐T MRI

“…However, aqueous phantoms have several disadvantages: T 1 and T 2 relaxation times are approximately equal and thus do not mimic human tissue well; further, aqueous solutions require a container to maintain form. Reported gel phantoms include agarose, 1-8 agar, [9][10][11][12] polyvinyl alcohol (PVA), 13 gelatin, 14 gelatin-agar, 15 the polysaccharide TX-150 (Ref. 16) and TX-151 (Ref.…”

Development of a human‐tissue‐like phantom for 3.0‐T MRI

“…Carrageenan is a gelling material similar to agar though relatively cheaper. While agarose [10][11][12] and agar 13,14 have been widely used as gelling agents for MRI phantoms, the benefits of carrageenan over other gels such as polysaccharide or gelatin, 15 include greater elasticity and strength, being formable into a large and stable phantom, and having an easily modified shape. 5 In contrast to agarose, carrageenan has a little influence on T 2 , making possible a phantom with a long T 2 value.…”

Multimodal Imaging of Hepatocellular Carcinoma Using Dynamic Liver Phantom

“…However, they are affected by motion artifacts and need a container to maintain shape [36]. Regarding gel phantoms, a lot of materials have been used in the literatures for fabricating MRI phantom including gelatin [38], gelatin-agar [39], agarose [40], agar [41], PVA [42], polysaccharide TX-150 [43], polysaccharide TX-151 [44], PAA [45], room-temperaturevulcanizing (RTV) silicone [46], and carrageenan [30,47].…”