【摘要】：第一部分不同掃描條件對(duì)囊腫假性強(qiáng)化的影響 目的：通過掃描腎臟的水模和模擬腎囊腫的不同直徑的試管，驗(yàn)證假性強(qiáng)化的存在，并評(píng)估背景濃度、病變直徑和容積CT劑量指數(shù)三種因素可能產(chǎn)生的影響。 方法：腎囊腫假性強(qiáng)化的研究使用長徑約100cm×31.5cm的圓筒作為模擬人體的水模。7.0cm×16cm的塑料水杯模擬腎臟，3只不同直徑的塑料試管模擬囊腫，其內(nèi)均裝滿蒸餾水，水杯內(nèi)先后裝滿10%葡萄糖液及一定濃度的含碘溶液，分別模擬平掃（30HU）、中等強(qiáng)化（90HU、125HU、180HU）及最大強(qiáng)化程度（240HU）的CT值。含碘劑的容器放入體模中心的底部，模擬脊柱。將雙源CT校機(jī)后行腹部常規(guī)掃描模式，根據(jù)掃描條件分成三組，A組管電壓為120KV，管電流為119mAs、CTDIvol為8.04mGy；B組管電壓為120KV，管電流178mAs，CTDIvol為12.03mGy；C組管電壓120KV，管電流297mAs，CTDIvol為20.08mGy。重建層厚均為1mm。以CT差值10HU為臨界值，評(píng)估各個(gè)背景濃度下囊腫有無假性強(qiáng)化。 結(jié)果：A組僅在240HU背景濃度下出現(xiàn)了假性強(qiáng)化，且直徑6mm的囊腫最顯著，為21HU。其余背景濃度下差值均小于10HU。B組10mm和6mm的囊腫在180HU和240HU背景下均出現(xiàn)假性強(qiáng)化，差值最大為240HU6mm的囊腫，為20.4HU。C組僅直徑6mm的囊腫在125HU和240HU背景濃度下有假性強(qiáng)化，且240HU背景下差值最大為12.7HU。背景濃度（F=17.587，p=0.0004）和直徑（F=4.214，P=0.023）與假性強(qiáng)化有關(guān)。背景濃度越高，直徑越小，假性強(qiáng)化越明顯。從8mGy到20mGy，假性強(qiáng)化值分別為21HU，20.4HU及12.7HU，因此隨著管電流的增大，CTDIvol的增加，假性強(qiáng)化值越來越小，但是各組中，不同背景濃度及不同直徑的囊腫假性強(qiáng)化出現(xiàn)的概率沒有顯著的規(guī)律。 結(jié)論：囊腫的假性強(qiáng)化是客觀存在的現(xiàn)象，背景濃度和囊腫直徑是影響假性強(qiáng)化的重要因素，且背景濃度越高，囊腫直徑越小，假性強(qiáng)化程度越大。常規(guī)掃描中假性強(qiáng)化的出現(xiàn)具有不確定性。 第二部分迭代重建算法對(duì)圖像質(zhì)量和假性強(qiáng)化的影響 目的：通過迭代重建算法，評(píng)估其對(duì)圖像質(zhì)量及假性強(qiáng)化的影響。 方法：模型的制備同第一部分。將雙源CT校機(jī)后行腹部常規(guī)掃描模式，管電壓120kv，管電流178mAs，CTDIvol=12.03mGy，SAFIRE第3濾波強(qiáng)度。以10HU為臨界值，分析各背景濃度囊腫的CT差值，認(rèn)為大于10HU為囊腫有假性強(qiáng)化，并分析添加SAFIRE前后假性強(qiáng)化程度的變化及噪聲的差異。 結(jié)果：模擬腎囊腫測得的CT值范圍是-3.5HU～17.4HU。不同直徑的囊腫均出現(xiàn)了CT值大于10HU的情況，尤其在240HU背景濃度下，假性強(qiáng)化明顯，且假性強(qiáng)化率達(dá)75%，表明隨著背景濃度的提高，直徑越小，假性強(qiáng)化值越大。差值最大出現(xiàn)在240HU背景下的6mm囊腫，為20.9HU。利用SAFIRE重建后，假性強(qiáng)化的程度與常規(guī)重建方法相比，沒有統(tǒng)計(jì)學(xué)意義，說明迭代重建技術(shù)SAFIRE不會(huì)影響假性強(qiáng)化的程度。但它會(huì)使噪聲明顯減低，下降最明顯的由之前的24.3下降到16.4，下降了33%。但總體看來，不同背景濃度其噪聲下降的程度沒有顯著的規(guī)律。 結(jié)論：迭代重建算法SAFIRE可以提高圖像質(zhì)量，使噪聲明顯減低，但對(duì)消除假性強(qiáng)化及強(qiáng)化程度無顯著作用。 第三部分能譜CT對(duì)囊腫假性強(qiáng)化的影響 目的：通過雙能掃描所獲得的CT值，評(píng)估雙能融合圖像及單能量圖像對(duì)假性強(qiáng)化的影響。 方法：模型的制備同第一部分。將雙源CT校機(jī)后進(jìn)行掃描，采用腹部雙能掃描模式，根據(jù)管電壓不同分為兩組，A組管電壓80-sn140kv，CTDIvol為11.87mGy；B組管電壓100-sn140kv，CTDIvol為12.03mGy，重建層厚均為1mm。將掃描數(shù)據(jù)傳入Dual energy軟件中，間隔10kev在40-190kev單能量圖像中進(jìn)行重建，測量囊腫CT值，并將雙能融合圖像傳入viewing中，測量囊腫CT值。以10HU為臨界值，分析雙能融合圖像及單能量圖像是否存在假性強(qiáng)化。 結(jié)果：單能量圖像中，相同掃描條件下，70kev、80kev及90kev各期與平掃的CT差值均小于10HU，表明這三種能量水平的圖像不存在假性強(qiáng)化。圖像信噪比的高低不一，沒有顯著規(guī)律。70kev、80kev及90kev圖像噪聲在統(tǒng)計(jì)學(xué)上沒有顯著差異，P值均大于0.05，但80kev圖像噪聲最小。雙能融合圖像中，A、B兩組各期與30HU背景濃度相比，CT差值均小于10HU，說明雙能融合圖像不存在假性強(qiáng)化。 結(jié)論：雙能融合圖像不存在假性強(qiáng)化，因此,雙能CT可以消除假性強(qiáng)化。70kev、80kev及90kev圖像均能消除假性強(qiáng)化，80kev圖像噪聲最小。第四部分腎囊腫假性強(qiáng)化：雙源CT的臨床研究 目的：搜集經(jīng)超聲、MR及CT多期掃描均診斷為單純性腎囊腫的病例，回顧性地分析常規(guī)掃描或雙能掃描所獲得的CT值，評(píng)估能譜CT在臨床研究中對(duì)囊腫假性強(qiáng)化的影響。 方法：所有患者行常規(guī)平掃后，經(jīng)肘靜脈團(tuán)注碘海醇非離子型造影劑90ml，速率為3.0ml/s，采集25s皮質(zhì)期(cortical phase)、70s皮髓質(zhì)期(corticomedullary phase)圖像，保存平掃及皮髓質(zhì)期圖像并進(jìn)行研究。第一組行腹部常規(guī)掃描模式，共13例患者18例囊腫，根據(jù)重建層厚不同再分為A組平掃5mm層厚，B組靜脈期5mm層厚，C組靜脈期1mm層厚。第二組13例患者共17例腎囊腫平掃先行腹部常規(guī)掃描模式，注射造影劑70s后行腹部雙能掃描模式。同樣根據(jù)重建層厚分為D組平掃5mm，E組靜脈期5mm和F組靜脈期1.5mm。通過測量不同期相及重建層厚的囊腫的CT值，分別分析常規(guī)和雙能掃描中，平掃和靜脈期圖像囊腫CT值的差異，以均數(shù)（HU）±標(biāo)準(zhǔn)差的方式表示。 結(jié)果：26例患者共測量了35例囊腫，直徑最小為7.0mm，最大為48.9mm。一、二兩組中，囊腫的大小無統(tǒng)計(jì)學(xué)差異（t=-0.114, P=0.910）。第一組的平均直徑為15.8±0.95mm，其中10例囊腫位于腎實(shí)質(zhì)內(nèi)（B組有2例出現(xiàn)假性強(qiáng)化，最大差值為12.3HU； C組有3例出現(xiàn)假性強(qiáng)化，最大差值為11.4HU），3例囊腫小于50%突出于腎臟輪廓（B組有1例出現(xiàn)假性強(qiáng)化，差值為11.4HU； C組有1例有假性強(qiáng)化，差值為14.2HU），3例囊腫大于50%位于腎臟輪廓之外（均無假性強(qiáng)化，差值均小于10HU）。常規(guī)掃描B組（t=6.377, P=0.0003）和C組（t=5.641, P=0.0001）均出現(xiàn)了假性強(qiáng)化。第二組的平均直徑為16.2mm±1.01，其中15例囊腫位于腎實(shí)質(zhì)內(nèi)（E組有1例有假性強(qiáng)化，差值為11.0HU；F組均未出現(xiàn)假性強(qiáng)化，最大差值為6.4HU）,2例囊腫大于50%位于腎實(shí)質(zhì)外（E組僅1例出現(xiàn)假性強(qiáng)化，，差值為12.4HU。F組仍無假性強(qiáng)化，最大差值為4.8HU）。雙能掃描E組（t=5.799, P=0.0001）有假性強(qiáng)化，F(xiàn)組（t=0.542, P=0.297）無假性強(qiáng)化。 結(jié)論：臨床研究驗(yàn)證了囊腫假性強(qiáng)化的存在，雙能CT薄層掃描可以去除假性強(qiáng)化現(xiàn)象。
[Abstract]:Part I the effect of different scanning conditions on pseudocyst enhancement of cysts.
Objective: To verify the presence of pseudoenhancement by scanning the water model of kidney and the test tubes with different diameters of simulated renal cyst, and to evaluate the possible effects of background concentration, diameter of lesion and volume CT dose index.
Methods: The pseudo-enhancement of renal cysts was studied by using a cylinder with a length of about 100 cm *31.5 cm as a plastic water cup to simulate human kidneys. Three plastic test tubes with different diameters were filled with distilled water. The water cup was filled with 10% glucose solution and iodine solution of a certain concentration, respectively, to simulate plain scan (3.0 cm *16 cm). CT values of 0 HU, moderate enhancement (90 HU, 125 HU, 180 HU) and maximum enhancement (240 HU) were measured. Containers containing iodine were placed at the bottom of the phantom center to simulate the spine. In group C, the tube voltage was 120 KV, the tube current was 297 mAs, and the CT DIvol was 20.08 mGy. The thickness of reconstructed slices was 1 mm. The CT difference of 10 HU was used as the critical value to evaluate whether the cysts had pseudoenhancement at various background concentrations.
Results: Pseudo-enhancement was found only at 240 HU background concentration in group A, and the cysts with a diameter of 6 mm were the most prominent at 21 HU. The difference between the other background concentrations was less than 10 HU. The background concentration (F = 17.587, P = 0.0004) and diameter (F = 4.214, P = 0.023) were related to false enhancement. The higher the background concentration, the smaller the diameter, the more obvious the false enhancement. From 8 mGy to 20 mGy, the false enhancement values were 21 HU, 20.4 HU and 12.7 HU, respectively. Therefore, with the increase of tube current, CTDIvol increased. With the increase of cyst size, the pseudo-enhancement value became smaller and smaller, but the probability of pseudo-enhancement of cysts with different background concentrations and diameters did not change significantly in each group.
Conclusion: Pseudo-enhancement of cyst is an objective phenomenon. Background concentration and cyst diameter are important factors affecting pseudo-enhancement. The higher the background concentration, the smaller the cyst diameter and the greater the degree of pseudo-enhancement.
The influence of the second part iterative reconstruction algorithm on image quality and false enhancement
Objective: To evaluate the effect of the iterative reconstruction algorithm on image quality and false enhancement.
Methods: The model was made in the same way as the first part. The dual-source CT was used in the abdominal scanning mode. The tube voltage was 120 kv, the tube current was 178 mAs, the CTDIvol=12.03 mGy, and the filtering intensity of SAFIRE was 3. The change of degree and the difference of noise.
Results: The range of CT values measured by simulated renal cysts was - 3.5HU to 17.4HU. The CT values of cysts with different diameters were greater than 10HU. Especially at 240HU background concentration, the pseudo-enhancement was obvious and the pseudo-enhancement rate was 75%. It showed that the smaller the diameter, the larger the pseudo-enhancement value. 6 mm cyst, 20.9 HU. After SAFIRE reconstruction, the degree of pseudo-enhancement was not statistically significant compared with the conventional reconstruction method, indicating that the iterative reconstruction technique SAFIRE would not affect the degree of pseudo-enhancement. But it would significantly reduce the noise, the most obvious reduction from 24.3 to 16.4, a 33% reduction. But overall, different backs. There is no significant regularity in the degree of noise reduction.
Conclusion: The iterative reconstruction algorithm SAFIRE can improve the image quality and reduce the noise, but has no significant effect on eliminating false enhancement and enhancement.
The third part is the effect of CT on pseudocyst enhancement.
Objective: To evaluate the effect of dual-energy fusion image and single-energy image on pseudo-enhancement by CT value obtained from dual-energy scanning.
Methods: The model was made in the same way as the first part. The dual-source CT was scanned after calibration and divided into two groups according to the tube voltage: group A tube voltage 80-sn140 kv, CTDIvol 11.87 mGy, group B tube voltage 100-sn140 kv, CTDIvol 12.03 mGy, and the reconstructed thickness was 1 mm. Kev was reconstructed in 40-190 keV single energy images, CT values of cysts were measured, and dual energy fusion images were transferred into viewing to measure CT values of cysts.
Results: Under the same scanning condition, the difference of CT between 70 kev, 80 keV and 90 keV phases and plain scan was less than 10 HU, indicating that there was no false enhancement in the three energy levels of images. But the noise of 80 keV image is the smallest. In the dual-energy fusion image, the difference of CT between A and B groups is less than 10 HU compared with the background concentration of 30 HU in each phase, which indicates that there is no false enhancement in the dual-energy fusion image.
Conclusion: Dual-energy CT can eliminate pseudo-enhancement. 70 kev, 80 keV and 90 keV images can eliminate pseudo-enhancement. 80 keV images have the least noise. Part IV: Clinical study of dual-energy CT: pseudo-enhancement of renal cyst
Objective: To collect cases of simple renal cyst diagnosed by ultrasonography, MR and CT multi-phase scanning, retrospectively analyze the CT value obtained by conventional scanning or dual-energy scanning, and evaluate the effect of energy-dispersive CT on pseudoenhancement of cyst in clinical research.
Methods: After routine plain scan, all patients were injected iohexol nonionic contrast agent 90 mL through the elbow vein at a rate of 3.0 ml/s. The cortical phase of 25 s and corticomedullary phase of 70 s were collected. The images of plain scan and corticomedullary phase were preserved and studied. According to the thickness of reconstructed slices, 17 cases of renal cysts in the second group underwent routine abdominal scanning, 70 s contrast medium was injected, and then abdominal dual-energy scanning. Phase 1.5mm. The CT values of cysts with different phases and thickness of reconstructed slices were measured, and the differences of CT values between plain and venous phases were analyzed in terms of mean (HU) + standard deviation.
Results: A total of 35 cysts were measured in 26 patients. The minimum diameter was 7.0 mm and the maximum was 48.9 mm. There was no significant difference in the size of cysts between the two groups (t = - 0.114, P = 0.910). The average diameter of cysts in the first group was 15.8 (+ 0.95 mm), of which 10 were located in the renal parenchyma (2 cases in group B had pseudoenhancement, the maximum difference was 12.3 HU; 3 cases in group C had pseudoenhancement). The maximum difference was 11.4 HU, and 3 cysts were less than 50% protruding from the contour of the kidney (1 case in group B, 11.4 HU; 1 case in group C, 14.2 HU; 3 cysts were more than 50% outside the contour of the kidney (all without false enhancement, the difference was less than 10 HU). Routine scan group B (t = 6.377, P = 0.0003) and group C (t = 0.0003) The second group had an average diameter of 16.2 mm (+ 1.01), of which 15 cysts were located in the renal parenchyma (1 case in group E had pseudo-enhancement with a difference of 11.0 HU; none in group F had pseudo-enhancement with a maximum difference of 6.4 HU), and 2 cysts were more than 50% outside the renal parenchyma (only 1 case in group E had pseudo-enhancement with a difference of 12.4 HU.F). There was no false enhancement in group E (t = 5.799, P = 0.0001) and no false enhancement in group F (t = 0.542, P = 0.297).
Conclusion: Clinical studies have confirmed the existence of pseudo-enhancement of cysts. Dual-energy CT thin-layer scanning can remove pseudo-enhancement.
【學(xué)位授予單位】：河北醫(yī)科大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：R816.7

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