Accuracy of the standard systematic 12-core transrectal ultrasound-guided biopsy on a prostate phantom model

OBJECTIVE@#The detection rate of the current standard systematic 12 core transrectal ultrasound (TRUS)guided prostate biopsy remains low despite numerous modifications of the technique. This non-randomized experimental study evaluated the accuracy of standard TRUS-guided systematic prostatebiopsy as performed by selected urologists in obtaining samples representative of the peripheral zoneof the prostate, by analyzing virtual biopsies performed on a prostate phantom model.@*MATERIALS AND METHODS@#Thirty (30) urologists (26 consultants and 4 senior residents) were invited toperform two consecutive simulation TRUS guided 12-core biopsies on a phantom prostate model.The task was to hit twelve equal sized spherical targets which would correspond to the lateral andextreme lateral areas of the base, mid gland and apex of the peripheral zone of the phantom prostate,which would represent the usual biopsy technique. Degree of agreement (kappa) was computed.Eight (8) operators had below satisfactory kappa values and were excluded from the succeedinganalysis. Accuracy was calculated by dividing the number of accurately hit targets by the number ofvirtual cores (12). Data were encoded in MS Excel and Stata MP v.14 was used for data analysis.@*RESULTS@#Overall, the mean accuracy was 63.17% and median accuracy was 60% (95% CI: 49.2-65.15)for the 22 operators included in the study. The lateral regions, particularly the midgland (95.8%-100% accuracy) were the most frequently biopsied areas and were often resampled. The targets at theprostatic base were missed by most operators (36.05% accuracy).@*CONCLUSION@#Systematic TRUS guided prostate biopsy, in the manner that it is performed, has itsinherent flaws, compounded by limitations in imaging capability and intra-operator variabilityresulting in low accuracy rates. A shift to newer prostate biopsy technique and methodologies withsignificantly higher accuracy rates is recommended.

Effect of Tube Current on the Pseudo-enhancement of Renal Cyst / 中国医学影像学杂志

PurposeTo evaluate the effect of tube current on the pseudo-enhancement of renal cyst by simulating the phantom model of simple renal cyst.Materials and Methods 10% glucose and iodine solution with a certain concentration was used to simulate the renal parenchymal background concentration in plain scan, moderate enhancement and maximum enhancement respectively. The diameters of the cysts were 6 mm, 10 mm and 15 mm, respectively, and the cysts were divided into three groups according to different tube current: 119 mAs (group A), 178 mAs (group B) and 297 mAs (group C) while the tube voltage were all 120 kV. Whether pseudo-enhancement exists in cyst under different conditions was determined using an increase of CT value of 10 HU as the critical value. Results In group A, there was pseudo enhancement at the 240 HU background, and it was most significant with the diameter of 6 mm, which was 21 HU. In group B, pseudo-enhancement occurred in cysts with diameter of both 10 mm and 6 mm under the background of 180 HU and 240 HU, moreover, the biggest difference was 20.4 HU and it occurred in cyst with diameter of 6 mm under the background of 240 HU. In group C, pseudo-enhancement only occurred in cyst with diameter of 6 mm under the condition of 125 HU and 240 HU background concentration. Background concentration (F=17.587, P<0.01) and cyst diameter (F=4.214,P<0.05) had greater impact on cyst pseudo-enhancement, the higher the background concentration and smaller the diameter, more significantly the pseudo-enhancement would occur. With the increase of the tube current, the CT volume dose index increased, and the pseudo enhancement value was smaller, but there was no obvious regularity of pseudo-enhancement occurrence rate in cysts with different background concentration and diameter in each group.Conclusion The increase of tube current cannot completely eliminate cyst pseudo-enhancement. High background concentration and small diameter cyst are important factors in pseudo-enhancement. However, increasing the tube current can reduce the probability of occurrence of pseudo-enhancement to some extent. For those with heavier body weight, it might be necessary to increase the tube current to improve image quality and reduce the occurrence of renal cyst pseudo-enhancement.

Comparison of different MR fat quantification methods at 3.0 T in a phantom study / 中华放射学杂志

Objective To investigate the value of MR imaging methods for the quantification of fat content in a customized lipid phantom at 3.0 T.Methods Eleven homogeneous fat-water phantoms (50 ml)with fat volume percentages from 0 to 100％ were constructed with reference to Bernard's methods.Fat tractions of the lipid phantom were acquired using water selective saturation (WS),fat selective saturation (FS),in-and out-of-phase imaging (IOP),iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient echo imaging and IDEAL Quant imaging methods on a 3.0 T MRI system.For statistical comparisons,paired-sample t test,Pearson correlation test,and Bland-Ahman maps were applied.Results Evaluated fat fractions acquired by WS,IDEAL Gradient echo imaging and IDEAL Quant were (49.6±28.8)％,(46.0±28.4)％,(51.0±32.0)％,the result has no significant difference with the true fat contents(t values were-0.186,-2.218,2.713;P values were 0.856,0.051,0.055).Evaluated fat fractions acquired by FS,corrected algorithm and IOP were (64.2±26.7)％,(58.9±31.9)％ and (45.3±32.3)％,these three kinds of methods have significant difference with the true fat contents (t values were 5.168,4.273,-6.441;P＜0.01).All the chemical shift imaging methods correlated with the true phantom model fat fractions,r values were 0.977(FS),0.978 (corrected algorithm),0.982 (WS),0.99 8(IOP),0.993 (IDEAL Gradient echo imaging),0.999 (IDEAL Quant) (all P＜0.01).Each method's 95％ confidence interval of the mean difference acquired by Bland-Altman map was WS (-14.7％ to 13.8％),FS (-3.6％ to 32.0％),corrected algorithm (-4.6％ to 22.5％),IOP(-9.4％ to 0.0％),IDEAL gradient echo imaging (-15.9％ to 7.8％),IDEAL Quant(-2.0％ to 4.0％).IDEAL Quant had the best correlation and confidence with the true fat fraction.Conclusions Chemical shift imaging methods (IOP,IDEAL Gradient echo imaging,IDEAL Quant) can acquire more accurate fat quantification results than chemical saturation imaging methods (FS,Corrected algorithm,WS) in a customized lipid phantom at 3.0 T.IDEAL Quant can acquire the best fat quantification result compared with the other imaging methods.

Improving the measurement precision of the phantom model by network decomposition method / 医疗卫生装备

It is a kind of precise method tomeasure the complex permittivities of the phantom model by vector network analyzer.But it is difficult tomeasure them accurately because the phantom model is jelly-like gel and is hard tobe shaped.Network decompositon method can be used toresolve it and it has great meaning tostudy the phantom model simulating the biologic tissue.

Measuring the complex permittivity of phantom model by perturbation method / 医疗卫生装备

It is the measurement of high-loss dielectric to measure the permittivity and conductivity of biologic tissue.But now it is difficult to measure them accurately.Good result is got by measuring complex permittivity of phantom model at2450MHz using perturbation method,which is meaningful for the research on biologic tissue simulation by phantom model.