【摘要】：目的：探討能譜CTA腦動(dòng)脈與腦組織最佳對(duì)比噪聲比曲線峰值的變化規(guī)律,并以此為基礎(chǔ)前瞻性對(duì)比評(píng)價(jià)能譜模式掃描與常規(guī)模式掃描減影去骨法腦動(dòng)脈CTA的圖像質(zhì)量。 材料和方法：連續(xù)74名接受頭顱CTA檢查的患者隨機(jī)分配至能譜掃描組和常規(guī)掃描組,采用GE DISCOVERY CT750HD掃描儀分別以能譜模式及常規(guī)模式進(jìn)行掃描,觀察能譜模式下虛擬單能量未減影增強(qiáng)腦動(dòng)脈與腦實(shí)質(zhì)最佳對(duì)比噪聲比曲線,記錄其兩個(gè)峰值對(duì)應(yīng)的虛擬單能量水平keV1、keV2,比較能譜掃描模式(?)得到的三組圖像(140kVp、keV1、keV2)以及常規(guī)掃描模式下的一組圖像(routine,120kVp)減影去骨法CT圖像的腦動(dòng)脈CT值、對(duì)比度、背景噪聲、對(duì)比噪聲比、信噪比以及腦動(dòng)脈CTA VR+segment/autoselect法重建圖像的去骨效果和腦動(dòng)脈圖像質(zhì)量(均為5分法評(píng)價(jià),1-差、2-較差、3-中等、4-良好、5-優(yōu)秀) 結(jié)果：虛擬單能量未減影增強(qiáng)腦動(dòng)脈與腦實(shí)質(zhì)最佳對(duì)比噪聲比曲線均表現(xiàn)為駝峰狀雙峰曲線,兩個(gè)峰值對(duì)應(yīng)的keV1、keV2的單能量水平分別為(55.19±2.05)keV、(64.92±1.16)keV。減影后140kVp、keV1、keV2、routine四組圖像間顱骨去除效果沒有差別χ2=3.85,p=0.280.05)。兩位放射科醫(yī)生對(duì)腦血管圖像質(zhì)量的主觀評(píng)價(jià)結(jié)果一致性較好,Kappa值為0.65,u=12.53,p=0.00(0.05)。Ridit分析R1140kVP=0.33, R1keV1=0.70, R1keV2=0.55, R1routine=0.42, χ2=35.52, P=0.000.05;R2,40kVP=0.31, R2keV1=0.68, R2keV2=0.57, R2routine=0.44, χ2=33.52, P=0.00(0.05四組圖像的主觀評(píng)分明顯有差別,四組圖像質(zhì)量從好到差排序?yàn)閗eV1、keV2、 routine、140kVp, keV1組圖像明顯好于其它三組。減影后140kVp、keV1、keV2、 routine四組圖像間的腦動(dòng)脈CT值、對(duì)比度、背景噪聲、對(duì)比噪聲比、信噪比均有差別,F值分別為38.849、38.620、7.995、11.342、10.982(p=0.000.05)。四組圖像中,keV1組腦動(dòng)脈CT值、對(duì)比度最高,keV2組與routine組居中,140kVp組最低；背景噪聲keV2組最低；對(duì)比噪聲比及信噪比keV1和keV2組無差別,140kVp與routine組無差別,keVl、keV2組高于140kVp和routine兩組。 結(jié)論： 1.未減影能譜掃描模式增強(qiáng)后腦動(dòng)脈與腦組織最佳對(duì)比噪聲比雙峰曲線峰值對(duì)應(yīng)的keV1組的平均虛擬單能量值約為(55.19±2.05)keV,keV2組的平均虛擬單能量值為(64.92±1.16)keV。 2.兩種模式掃描四組圖像用減影以及VR+segment/autoselect軟件綜合法去骨的效果相仿并都可基本消除減影后的殘留顱骨,優(yōu)于現(xiàn)行的去骨法。 3.與常規(guī)掃描模式減影腦CTA相比,能譜掃描模式下取得的140kVp圖像,其減影CTA圖像質(zhì)量差,因此只適合于用于作為血管強(qiáng)化程度的參考圖像。 4.能譜掃描模式的keVl、keV2組減影去骨法腦CTA可以明顯提高圖像質(zhì)量,更清晰的顯示腦動(dòng)脈,可以取代常規(guī)掃描模式更好的顯示腦動(dòng)脈。keV1組圖像較keV2組圖像質(zhì)量更優(yōu)秀,keV1組的平均值約為55keV,因此建議以55keV為能譜掃描常規(guī)后處理的虛擬單能量圖像顯示腦動(dòng)脈,從而優(yōu)化能譜數(shù)據(jù)的后處理流程。
[Abstract]:Objective: to investigate the changes of the peak value of the optimal contrast noise ratio curve between cerebral artery and brain tissue in energy spectrum CTA, and to evaluate the image quality of CTA by energy spectrum mode scanning and conventional mode scanning subtraction. Materials and methods: 74 consecutive patients undergoing skull CTA were randomly assigned to energy spectrum scanning group and routine scanning group. GE DISCOVERY CT750HD scanner was used to scan in energy spectrum mode and conventional mode respectively. The optimal contrast noise ratio curve of virtual single energy unsubtraction enhanced cerebral artery and brain parenchyma in energy spectrum mode was observed, and the virtual single energy level keV1,keV2, comparative energy spectrum scanning mode corresponding to the two peaks was recorded. The CT values, contrast, background noise, contrast noise, signal-to-noise ratio, signal-to-noise ratio (SNR), bone removal effect and cerebral artery image quality of three groups of images (140kVP, KeV1, Kev2) and a group of images (routine,120kVp) subtracted from conventional scanning mode (CT) subtractive images, contrast, background noise, signal-to-noise ratio, signal-to-noise ratio (SNR) and cerebral artery image quality (all evaluated by 5 points method, 1-difference, 2-poor, 3-medium, 4-good. Results: the optimal contrast noise ratio curve between cerebral artery and cerebral parenchyma was hump bimodal curve, and the single energy level of keV1,keV2 corresponding to the two peaks was (5519 鹵2.05) keV, (64.92 鹵1.16) keV., respectively. After subtraction, there was no difference in skull removal effect among the four groups of images, such as 140kVp, KeV1, KeV2 and routine. There was no difference in skull removal effect between the four groups (P 鈮，

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