The In Vitro Experimental And Clinical Study Of Cyst Pseudo-enhancement

Part Ⅰ Pseudo-enhancement of cyst: influence of multi-phase of MSCTObjective: To validation pseudo-enhancement of cyst by scanning watermode and different diameters of the tubes that on behalf of kidney and renalcysts respectively, then assess the possible effects produced by the backgroundconcentrations, diameters and CTDIvol.Methods: Length of about100cm and diameter about31.5cm cylindricalwater phantom as a simulated human body, the kegs With a diameter of7.0cm,length about16cm as kidney. Three different diameter plastic tubes simulatedcyst. Three test tubes filled with distilled water, a small bucket filled with10%glucose solution and a certain concentration of iodine solution, respectively, tosimulate the non-enhancement (30HU), renal cortical phase (90HU), Medullaperiod (125HU), renal delay phase (180HU) and the maximum degree ofenhancement (240HU). The keg had been put below in a container containingiodine which simulates the spine. Use routine abdominal scan mode afterSOMATOM Definition Flash CT calibration. According to the scanningconditions divided into three groups，A group was120KV, the tube currentwas119mAs, CTDIvol was8.01mGy. B group was120KV,178mAs and12.03mGy. C group was120KV,297mAs, and20.08mGy. Reconstructionthickness was1mm. Assess the false aggrandizement under backgroundconcentrations as10Hu be the critical value.Result: In group A, only240HU background concentration appearedfalse aggrandizement, and the biggest difference is21HU in cyst of6mm.Under the other background concentration the difference are less than10HU.In group B,180HU and240HU background concentrations both appearedfalse aggrandizement, and the biggest difference is20.4HU in cyst of6mm. Ingroup C, only6mm cyst in125HU and240HU background concentrations appeared false aggrandizement, and the biggest difference is12.7HU in240HU background concentration. Cyst diameter (P=0.023) and backgroundconcentration (P=0.0004) are important reasons influencepseudo-enhancement. So the background concentration is higher, the greaterthe probability of false aggrandizement. And with the increase of tube currentand CTDIvol increases, pseudo reinforcement degree is more and more small.But among groups, the probability of pseudo-enhancement appeared nosignificant regularity in different background concentrations and the diameterof the cyst.Conclusion: The pseudo enhancement of cyst is objective existence ofthe phenomenon. The background concentration and cyst diameter are theimportant factors that affect false aggrandizement. And Backgroundconcentration is higher, the cyst diameter is smaller, the pseudo reinforcementdegree is bigger. The emergence of pseudo enhancement is instability inroutine scan.Part Ⅱ Influence of iterative reconstruction algorithm on image qualityand pseudo-enhancementObjective: To assess the impact on the image quality andpseudo-enhanced by iterative reconstruction algorithm.Methods: The preparation of model was the same with the first part. Useroutine abdominal scan mode after SOMATOM Definition Flash CTcalibration. Using120KV, the tube current were178mAs, CTDIvol for12.03mGy, and SAFIRE was selected strength3. Assess the falseaggrandizement under background concentrations as10Hu be the criticalvalue, and analysis the pseudo-enhancement degree and the difference of noisebefore and after adding SAFIRE.Result: Simulation of renal cyst CT value range that measured was-3.5HU～17.4HU. Under the background of240HU, the rate of pseudostrengthen is75%. And Background concentration is higher, the cyst diameteris smaller, the pseudo reinforcement degree is bigger. The biggest differencewas20.9HU in240HU background concentration in6m cyst. After adding SAFIRE, pseudo-enhancement has no statistically significant compared withbefore, that means SAFIRE does not affect levels of pseudo-enhancement.However, SAFIRE can reduce noise significantly, the most obvious is33%,but with no regularity.Conclusion: SAFIRE can improve image quality significantly, but has noeffect on pseudo strengthened and enhanced level.Part Ⅲ Pseudo-enhancement of cyst: influence of multi-phase ofdual-energy CTObjective: Assess the influence of dual-energy fusion image andsingle-energy image on pseudo-enhancement by CT values obtained by dualenergy scan.Methods: The preparation of model was the same with the first part. Useabdominal dual energy scan mode after SOMATOM Definition Flash CTcalibration. According to the different tube voltage can be divided into twogroups. The tube voltage was80-sn140kv, CTDIvol was11.87mGy in group A,and in group B, the tube voltage was100-sn140kv, CTDIvol was12.03mGyrespectively. Reconstruction thickness was1mm. Send data to dual energysoftware, and measure CT values of cysts in40-190kev images every10kev.In addition, send fusion images to viewing to measure CT values. As10HU bethe critical value, analysis if the fusion images and single energy images existfalse aggrandizement.Result: pseudo-enhancement does not exist in70、80、90kev imagesunder the same scan condition. The noise of80kev images is minimal, but theSNR has no statistical difference. So all things considered, the best energylevel is80kev. In fusion images, compared with30HU background, there areno significant differences in A and B group, which means there are no falseenhanced in fusion images.Conclusion: There is no pseudo-enhancement in fusion images, therefore,dual-energy CT can eliminate pseudo-enhancement.80kev is the best energylevel in single-energy images. Part Ⅳ Pseudo-enhancement of cyst: a new generation of Hyun-speeddual-source CT of clinical studyObjective: The study collected by ultrasound, MR and CT multi-phasescan common diagnosis of renal cyst disease. Retrospective analysis of the CTvalues obtained by routine scan or dual-energy scan, then assess the influenceof dual-energy CT on pseudo-enhancement of cysts in clinical study.Methods: All patients underwent routine unenhanced (precontrast), afterelbow omnipaque bolus90ml of non-ionic contrast agent, rate of3.0ml/s.Cortex were collected on25s,70s on corticomedullary phase image, and saveprecontrast images and corticomedullary phase images for study. In first group,there were13cases of patients with abdominal routine scan mode, andreconstruction slice was5mm for precontrast images (A group), with a thicklayer of vein period for5mm (B group) and1mm(C group). Another13caseswere in the second group, a total of17renal cysts with routine abdominal scanmode,70s after injection of contrast agents selected multi-phase scandual-energy mode. Reconstruction slice is5mm for precontrast images (Dgroup), with a thick layer of vein period for5mm (E group) and1.5mm (Fgroup). Respectively analyzed the difference of CT values betweenpreconstrast images and venous phase images by measuring CT values ofcysts in different periods and reconstruction slices, and expressed by means ofCT±SD.Result:35cases of cyst were measured, the minimum diameter is7.0mm,48.9mm maximum. The size of the cyst has no statistical difference intwo kinds of scanning methods (t=-0.114, P=0.910).13cases of patients withabdominal routine scan mode, and the average diameter is1.58±0.95mm.Among them10cases of cyst is located within the renal parenchyma(there are2cysts exist pseudo-enhancement in group B. the biggest difference is12.3HU, and3cysts exist pseudo-enhancement in group C, the biggest differenceis11.4HU),3cases of cysts less than50%of the outstanding in the profileoutside(there is1cyst exists pseudo-enhancement in group B. the biggestdifference is11.4HU, and1cysts exists pseudo-enhancement in group C, the biggest difference is14.2HU),3cases over50%of cysts protruding outsidethe renal contour(there in no pseudo-enhancement).Both the5mmreconstruction slice (t=6.377, P=0.0003) and1mm reconstruction slice(t=5.641, P=0.0001) exist pseudo-enhancement.17cases selected multi-phasescan dual-energy mode, and the average diameter is1.62±1.01mm. Including15cases of cyst is located within the renal parenchyma (there is1cyst existspseudo-enhancement in group E. the biggest difference is11.0HU, and nopseudo-enhancement in group F),2cases over50%of cysts protrudingoutside the renal contour (there is1cyst exists pseudo-enhancement in groupE. the biggest difference is12.4HU, and no pseudo-enhancement in group F).5mm reconstruction slice (t=6.377, P=0.0003) in dual-energy scan existpseudo-enhancement, while1.5mm reconstruction slice (t=0.542, P=0.297)have no Pseudo reinforcement.Conclusion: The clinical research verified the existence ofpseudo-enhancement of cyst. Dual-energy CT thin scan can eliminate thephenomenon of Pseudo reinforcement.