Numerical simulation of pulse wave propagation and parameter analysis based on transmission line model / 医用生物力学

Objective To numerically simulate the propagation of pulse wave in human arterial tree by proposing a novel calculation method which combines a transmission line model and a recursive algorithm of input impedance, and to study the effects of individual differences and arterial tree parameters on pulse wave so as to provide references for the analysis on physiologic and pathologic characteristics of human arterial tree. MethodsThe transmission line model of human arterial tree was constructed, which consisted of 55-segment large and medium sized arteries. The recursive algorithm was applied to compute the input impedance of arterial tree at each point. The blood pressures and flows of 55 arteries were calculated and showed in the distribution graphs. Based on this method, the effects of height, heart rate, stroke volume, internal radius and wall thickness on pulse wave propagation and blood pressure distribution were compared. Results The simulation results were in good agreement with the general rules of pulse wave propagation. The propagation of pulse wave in arterial tree showed significantly different characteristics for different parameters. Conclusions The proposed method can effectively simulate the propagation of pulse wave in arterial tree and accurately reflect the effects of individual differences and hemodynamics parameters on pulse wave propagation, and it is an important assistant means for the pathophysiologic analysis and diagnosis of human arterial tree.

Characteristic finding of renal oncocytoma and clear-cell renal cell carcinoma with multiphase CT / 中华放射学杂志

ObjectiveTo evaluate characteristic imaging findings of tumor attenuation in 4-phase CT between renal oncocytoma ( RO ) and clear-cell renal ceil carcinoma ( ccRCC ) of small tumor size (≤Scm).Methods Fifty-six patients with histologically confirmed renal masses (11ROs and 45 ccRCCs) were included in this study.Heterogeneous enhancement was found all tumors during the corticomedullary phase (CMP).The CT values of the normal renal cortex,the relatively high enhanced region and the relatively less-enhanced region of the tumor were measured in each phase.Statistical comparison was carried out by Chi-square test or Mann-Whitney test.ResultsIn CMP,the CT value of the relatively high enhanced region in RO [ 163.0 HU ( 141.0—178.0 HU) ] was significantly lower than that in ccRCC [ 194.0 HU ( 166.5—235.0 HU) ; Z = -2.847,P =0.004].Compared CMP with the excretory phase,the attenuation of the relatively highly enhanced region in RO [70.0 HU (41.0—86.0 HU)] were significantly lower than that in ccRCC [87.0 HU (65.0—126.5 HU) ] (Z= -2.032,P =0.042).In the excretory phase,9 of 11 ROs had a further enhancement with its relatively less-enhanced region which was significantly higher than that in ccRCC (21/45 ; x2 = 4.391,P = 0.036).ConclusionsIn CMP,the CT value of the relatively high enhanced region in RO was significantly lower than that in ccRCC.Compared with ccRCC,in the excretory phase,the RO had less attenuation of the relatively highly enhanced region with homogeneous density.