發(fā)布時(shí)間：2018-04-28 08:14

  本文選題：螺距 + 圖像質(zhì)量��； 參考：《山東中醫(yī)藥大學(xué)》2013年碩士論文

【摘要】：目的：：探討不同螺距對(duì)老年COPD患者64層胸部CT圖像質(zhì)量的影響。 資料與方法：選取2010年8月-2012年5月在本院行64層CT檢查的COPD患者。男52例，女48例，年齡65～92歲，平均72.5歲。使用GE Lightspeed sys#vct64層螺旋CT機(jī)進(jìn)行胸部掃描，將患者分為２組：A組（50例）采用螺距0.984，B組（50例）采用螺距1.375,其它掃描參數(shù)兩組基本一致,管電壓120kV，管電流200mA，掃描層厚5mm，準(zhǔn)直寬度40mm。掃描范圍由肺尖部向下至肺底。圖像主觀評(píng)價(jià)方法，3名高年資影像診斷醫(yī)師，在病史和掃描方式都不知情的情況下進(jìn)行獨(dú)立分析圖像并對(duì)圖像質(zhì)量評(píng)級(jí)，評(píng)分采用3分級(jí)法：1分為圖像質(zhì)量為優(yōu)，圖像清晰，各橫斷面肺野的肺血管、氣管及以下分支，顯示清晰、銳利；縱隔內(nèi)組織結(jié)構(gòu)清楚；能分辨細(xì)小血管斷面(圖1)；2分為圖像質(zhì)量為良，欠清晰(不影響診斷)：橫斷層面出現(xiàn)肺血管、氣管及支氣管分支邊緣模糊，，細(xì)小血管斷面可見(jiàn)(圖2)；3分為圖像質(zhì)量為差，模糊(影響診斷)：連續(xù)1～3個(gè)橫斷層面(尤其有病灶層面)出現(xiàn)肺血管、氣管走行呈“雙管”影或心影、膈肌“雙邊”影，病灶邊緣模糊，細(xì)小血管斷面顯示不清(圖3)。圖像噪聲測(cè)量,在降主動(dòng)脈、背部肌肉，選取位置相同的感興趣區(qū)，以CT值的標(biāo)準(zhǔn)差作為圖像噪聲。為避免測(cè)量誤差，降主動(dòng)脈和背部肌肉水平分別選取三個(gè)層測(cè)量，圖像CT值取其平均值。統(tǒng)計(jì)學(xué)分析：應(yīng)用SPSS11.5軟件分析，P值＜0.05為差異有統(tǒng)計(jì)學(xué)意義。 結(jié)果：100例病例中，A組50例出現(xiàn)呼吸運(yùn)動(dòng)偽影17例，偽影發(fā)生率為34％，B組出現(xiàn)呼吸運(yùn)動(dòng)偽影4例，偽影發(fā)生率為8％，偽影發(fā)生率較A組減少了26％，2種掃描方法偽影發(fā)生率在統(tǒng)計(jì)學(xué)上具有顯著性差異(P0.05)見(jiàn)表1。兩組圖像主觀評(píng)分無(wú)顯著差異，見(jiàn)表2。兩組噪聲對(duì)比無(wú)顯著差異，見(jiàn)表3。兩組掃描時(shí)間有明顯差異(P0.05)，B組明顯短于A組，見(jiàn)表4。 結(jié)論：老年COPD患者的胸部CT掃描，在管電壓（ｋＶ）和管電流（ｍＡ）恒定不變的情況下，應(yīng)用螺距1.375與螺距0.984比較，減少運(yùn)動(dòng)偽影的產(chǎn)生是可行的、有效的，在保證肺組織圖像質(zhì)量的同時(shí)，呼吸運(yùn)動(dòng)偽影相對(duì)減低，可以同時(shí)達(dá)到降低輻射劑量的目的，減少輻射損傷。
[Abstract]:Objective: to investigate the effect of different pitch on 64 slice CT image quality in elderly patients with COPD. Materials and methods: COPD patients who underwent 64-slice CT from August 2010 to May 2012 were selected. There were 52 males and 48 females, aged 6592 years (mean 72.5 years). The patients were divided into two groups: group A (n = 50) and pitch 0.984B (n = 50). The other scan parameters were basically the same. The voltage of the tube was 120kV, the current of the tube was 200mA, the thickness of scanning slice was 5mm, and the width of collimation was 40mm. The scanning range was from the apex of the lung to the bottom of the lung. The image subjective evaluation method: 3 senior image diagnostics were analyzed independently and rated the image quality without knowing the medical history and the scanning method. The score was divided into three grades: the image quality was the best, the image was clear, and the image was clear. The pulmonary blood vessels, trachea and below branches of the cross section of the lung field are clear and sharp; the structure of the mediastinal tissue is clear; the fine blood vessel section can be distinguished (fig. 1: 2) the quality of the image is good. Unclear (not affecting the diagnosis): pulmonary vessels appeared on the transverse plane, the edges of the trachea and bronchus branches were blurred, and the small blood vessels were visible on the cross-section (fig. 2 / 3), the quality of the images was poor. Fuzzy (influence diagnosis): pulmonary vessels appeared on 1 ~ 3 transected plane (especially with lesion), trachea was "double tube" or cardiac shadow, diaphragm was "bilateral", the edge of lesion was blurred, and the small blood vessel was not clear on section (Fig. 3). Image noise measurement, in descending aorta, back muscles, select the same position of the region of interest, using the standard deviation of CT value as image noise. In order to avoid the measurement error, the descending aorta and back muscle were measured in three layers, and the average value of CT image was calculated. Statistical analysis: SPSS11.5 software was used to analyze P < 0. 05 as the difference was statistically significant. Results among 100 cases, 17 cases of respiratory motion artifacts appeared in group A and 4 cases in group B (group B). The incidence of artifact was 8%. The incidence of artifact was 26% less than that in group A. There was a statistically significant difference in the incidence of artifact between the two methods (P 0.05), as shown in Table 1. There is no significant difference in image subjective scores between the two groups, as shown in Table 2. There is no significant difference in noise between the two groups, as shown in Table 3. There was a significant difference between the two groups in scanning time. Group B was significantly shorter than group A, as shown in Table 4. Conclusion: it is feasible and effective to reduce motion artifacts by using pitch 1.375 and pitch 0.984 in chest CT scan of elderly patients with COPD under the condition of constant tube voltage and tube current. While ensuring the image quality of lung tissue, the respiratory motion artifact is relatively low, which can reduce the radiation dose and reduce the radiation damage at the same time.
【學(xué)位授予單位】：山東中醫(yī)藥大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：R816.41;R563.9

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