ABSTRACT
Objective Taking pig kidney as an example, through a series of comparative and analogical experiments, the influencing factors of compressive stress at relaxation stage of biological tissues were analyzed, and a more accurate and widely applicable biomechanical model at relaxation stage was established. Methods The compressive stress relaxation experiments of pig kidney under different conditions were carried out by using the self-built mechanical experiment platform. The collected data were analyzed and mapped, and various factors affecting the relaxation force changes were summarized. Based on the conclusion, the neural network learning algorithm was used to model the force change process at relaxation stage of pig kidney. Results The pre-extrusion pressure and relaxation time were the main influencing factors for compressive stress changes of biological tissues at relaxation stage. The average error of test sample validation experiment was 6.4 mN, and the average prediction error of generalization sample validation experiment was 34.9 mN, so the modeling effect was good. Conclusions Neural network modeling algorithm has the advantages of strong generalization ability and good fault tolerance, which contributes to providing more realistic force tactile feedback prediction for virtual surgery system. It is also a new idea for mechanical modeling of nonlinear biological tissues.
ABSTRACT
Objective: To explore the effect of three-dimensional reconstruction of abdominal organ CT images based on improved moving cube algorithm. Methods: An adaptive improved marching cube algorithm based on the universal tree structure and the contour points method based on the regional growth method were proposed. Firstly, the medical images were segmented, and all the voxels intersecting with the threshold were marked after the seed points were selected. A general tree structure was created to insert intersecting voxels into sub-nodes and determine the vertex index method based on the general tree. Simplify the acquisition of equivalence information by moving equivalence points to merge coplanar triangles. Based on abdominal CT images of a volunteer, a three-dimensional kidney model was constructed by using traditional moving cube algorithm and improved moving cube algorithm, and the effects were compared. Results: Compared with traditional algorithm, the triangle facets generated with the improved moving cube algorithm were reduced by 39.20%, the efficiency of the algorithm was improved by 37.59%, the surface of the three-dimensional model was smooth and lifelike, and the local details were more accurate. Conclusion: Based on the improved moving cube algorithm, three-dimensional reconstruction of abdominal organs in CT images can be achieved quickly and accurately.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the efficacy and safety of deferasirox in aplastic anemia (AA)patients with iron overload.</p><p><b>METHODS</b>A single arm, multi- center, prospective, open- label study was conducted to evaluate absolute change in serum ferritin (SF)from baseline to 12 months of deferasirox administration, initially at a dose of 20 mg·kg(-1)·d(-1), and the safety in 64 AA patients with iron overload.</p><p><b>RESULTS</b>All patients started their deferasirox treatment with a daily dose of 20 mg · kg(-1) ·d(-1). The mean actual dose was (18.6±3.60) mg · kg(-1)·d(-1). The median SF decreased from 4 924 (2 718- 6 765)μg/L at baseline (n=64) to 3 036 (1 474- 5 551)μg/L at 12 months (n=23) with the percentage change from baseline as 38%. A median SF decrease of 651 (126-2 125)μg/L was observed at the end of study in 23 patients who completed 12 months' treatment, the median SF level decreased by 1 167(580-4 806)μg/L [5 271(3 420-8 278)μg/L at baseline; 3 036(1 474-5 551)μg/L after 12 months' treatment; the percentage change from baseline as 42% ] after 12 months of deferasirox treatment. The most common adverse events (AEs) were increased serum creatinine levels (40.98%), gastrointestinal discomfort (40.98%), elevated liver transaminase (ALT: 21.31%; AST: 13.11%)and proteinuria (24.59%). The increased serum creatinine levels were reversible and non-progressive. Of 38 patients with concomitant cyclosporine use, 12(31.8%)patients had two consecutive values >ULN, 10(26.3%)patients had two consecutive values >1.33 baseline values, but only 1(2.6%)patient's serum creatinine increased more than 1.33 baseline values and exceeded ULN. For both AST and ALT, no patients experienced two post- baseline values >5 ×ULN or >10 × ULN during the whole study. In AA patients with low baseline PLT count (less than 50 × 10(9)/L), there was no decrease for median PLT level during 12 months' treatment period.</p><p><b>CONCLUSIONS</b>AA patients with iron overload could achieve satisfactory efficacy of iron chelation by deferasirox treatment. The drug was well tolerated with a clinically manageable safety profile and no major adverse events.</p>