能譜CT單能量成像技術(shù)消除椎弓根釘固定術(shù)后金屬偽影的研究
發(fā)布時間：2018-09-14 20:54
【摘要】：目的：研究能譜CT單能量成像（單keV）技術(shù)在去除脊柱金屬植入物術(shù)后金屬偽影方面的臨床價值，并評價金屬鄰近區(qū)域的組織在去除偽影后的診斷可信度。 材料與方法：收集本院35例腰椎椎弓根釘內(nèi)固定術(shù)后患者，行能譜CT能譜掃描(Gemstone Spectral Imaging, GSI)，用GSI viewer重建出5mm140kVp圖像，并以10keV的間隔重建40~140keV范圍的11組單能量圖像�？陀^評價:（1）選擇椎弓根釘最完整層面圖像，在金屬鄰近區(qū)域選擇12個感興趣區(qū)（region ofinterest，ROI）并選擇1個背景ROI，測量每個ROI的CT值、噪聲即SD值（StandardDeviation，SD），分別計算金屬周圍12個ROI的偽影指數(shù)（artifacts index，AI）；（2）選擇椎弓根釘層面和鄰近無椎弓根釘?shù)淖倒鶎用鎴D像，分別于椎管、腰大肌處選擇ROI，測量其CT值、SD值。主觀評價：2位具有中級職稱的放射科醫(yī)師對140kVp圖像、40~140keV單能量圖像行雙盲法主觀評分。評分方法：根據(jù)偽影對圖像質(zhì)量的影響程度予以記3、2、1、0分。3分為圖像質(zhì)量好,基本無偽影，金屬釘及椎弓根皮質(zhì)顯示清晰，軟組織對比良好;2分為圖像質(zhì)量較好,有部分偽影，金屬釘及椎弓根皮質(zhì)顯示尚清晰，軟組織基本顯示清楚;1分為偽影較重,圖像尚能觀察，金屬釘及椎弓根皮質(zhì)顯示欠清晰;0分為偽影很重,圖像無法觀察。統(tǒng)計學方法：所有統(tǒng)計學分析均使用SPSS19.0軟件，以p0.05為差異具有統(tǒng)計學意義。對金屬釘周圍12個ROI的AI值取對數(shù)后進行單因素方差分析，并用LSD檢驗進行多重對比；對椎管、腰大肌CT值、SD值在椎弓根釘層面和無椎弓根釘?shù)淖倒鶎用鎴D像之間分別進行配對樣本t檢驗；對主觀評分行單因素方差分析，并應(yīng)用LSD檢驗進行多重對比。 結(jié)果： 1、客觀評價：（1）隨著keV增加，AI均值逐漸降低；雙側(cè)椎弓根旁90~140keV組間的AI值差異無統(tǒng)計學意義，，余感興趣區(qū)100~140keV組間的AI值差異無統(tǒng)計學意義（p0.05）。與140kVp組比較,右側(cè)椎弓根外、椎體前方、椎體、棘突后方70keV、80keV水平AI值差異無統(tǒng)計學意義（p0.05），余感興趣區(qū)在70keV水平AI差異無統(tǒng)計學意義（p0.05），其余keV水平AI值差異均有統(tǒng)計學意義，其中40~60keV組的AI均值大于140kVp圖像AI均值，90~140keV水平其AI均值小于140kVp圖像的AI均值。（2）椎弓根釘層面和無椎弓根釘層面腰大肌、椎管CT值分別于100~120keV、120~140keV水平差異無統(tǒng)計學意義（p0.05）；椎弓根釘層面和無椎弓根釘層面腰大肌SD值、椎管SD值在140kVp圖像、40~140keV單能量圖像上差異均有統(tǒng)計學意義（p0.05），隨著keV增加差值的絕對值變小，其中100~140keV差值相近。 2、主觀評價：隨著keV增加，圖像偽影減少，椎弓根釘及椎弓根皮質(zhì)顯示更清晰，但周圍組織對比度降低，椎弓根釘直徑變細。120~140keV水平圖像主觀評分差異無統(tǒng)計學意義（p0.05）；80keV圖像與140kVp圖像評分差異無統(tǒng)計學意義（p=0.607），余keV水平單能量圖像與140kVp圖像主觀評分差異均有統(tǒng)計學意義（p0.05）。 結(jié)論： 1、能譜CT單能量成像技術(shù)可有效降低腰椎椎弓根釘內(nèi)固定術(shù)后的金屬偽影，其中高能量水平（100~140keV）去除脊柱金屬植入物偽影效果更佳。不同位置理想的重建單能量水平具有良好的一致性，100keV為理想重建能量水平。 2、120keV單能量圖像椎弓根釘周圍組織CT值比較真實，提示臨床上測量CT值的理想圖像應(yīng)以該能量水平重建。單能量成像技術(shù)可在一定程度上校正偽影，但不能完全消除偽影。 3、降低偽影與圖像質(zhì)量是相互制約關(guān)系：即隨著keV增高，偽影減少，但圖像對比度降低；因此在重建圖像選擇能量水平時，應(yīng)合理平衡圖像質(zhì)量與偽影的關(guān)系，而并非keV值越高越好。
[Abstract]:Objective: To evaluate the clinical value of single-energy computed tomography (single keV) in removing metal artifacts after spinal metal implantation and to evaluate the diagnostic reliability of adjacent tissues after removing the artifacts.
Materials and Methods: 35 cases of lumbar pedicle screw internal fixation in our hospital were collected. The images of 5 m 140 kVp were reconstructed by energy spectrum CT imaging (GSI) and 11 groups of single energy images were reconstructed by 10 keV interval from 40 keV to 140 keV. Twelve regions of interest (ROI) were selected in the adjacent region and one background ROI was selected to measure the CT value of each ROI, and the artifacts index (AI) of 12 ROIs around the metal was calculated. 2) The images of pedicle screw level and pedicle level of adjacent non-pedicle screw level were selected. Subjective evaluation: Two radiologists with intermediate professional titles scored 140 kVp images and 40-140 keV single-energy images by double-blind method. Scoring method: 3,2,1,0 points were scored according to the influence of artifacts on image quality. Pedicle cortex showed clearly, soft tissue contrast was good; 2 was divided into good image quality, some artifacts, metal nails and pedicle cortex showed clearly, soft tissue showed clearly; 1 was heavier artifacts, image still can be observed, metal nails and pedicle cortex showed less clearly; 0 was very heavy artifacts, image could not be observed. SPSS19.0 software was used for all statistical analysis, and P0.05 was used for statistical significance. The AI values of 12 ROIs around the screw were logarithmically analyzed by one-way ANOVA, and LSD was used for multiple comparisons. CT values of vertebral canal, psoas major muscle, and SD values were divided between pedicle screw level and pedicle level images without pedicle screw. Paired sample t test was used, subjective score was analyzed by one-way ANOVA, and LSD test was used for multiple comparisons.
Result:
1. Objective evaluation: (1) With the increase of keV, AI values gradually decreased; there was no significant difference in AI values between 90-140 keV groups near the bilateral pedicles, and no significant difference in AI values between 100-140 keV groups in the remaining regions of interest (p0.05). Compared with 140 kVp group, there was no significant difference in AI values of 70 keV and 80 keV levels outside the right pedicle, in the front of the vertebral body, in the vertebral body and behind the spinous process. There was no significant difference in AI at 70 keV level among the remaining regions of interest (p0.05). There were significant differences in AI values at other keV levels. The AI mean of 40-60 keV group was higher than that of 140 kVp group. The AI mean of 90-140 keV group was less than that of 140 kVp group. (2) The AI mean of psoas major muscle at pedicle screw level and non-pedicle screw level was higher than that of 140 kVp group. There was no significant difference in CT values between 100 and 120 keV, 120 and 140 keV (p0.05); SD values of psoas major muscle at pedicle screw level and non-pedicle screw level, SD values of spinal canal in 140 kVp images and 40 to 140 keV single energy images were statistically significant (p0.05). The absolute value of the difference decreased with the increase of keV, and the difference between 100 and 140 keV was similar.
2. Subjective evaluation: With the increase of keV, the artifacts decreased, the cortex of pedicle screw and pedicle screw showed clearer, but the contrast of surrounding tissues decreased, and the diameter of pedicle screw became thinner. There was no significant difference in subjective score between 120 and 140 keV images (p0.05); there was no significant difference in subjective score between 80 keV images and 140 kVp images (p = 0.607). There was a statistically significant difference in the subjective scores of flat single energy and 140kVp images (P0.05).
Conclusion:
1. Spectral CT single-energy imaging can effectively reduce the metal artifacts after lumbar pedicle screw fixation, and high-energy level (100-140 keV) is more effective in removing the metal implant artifacts.
2,120 keV single-energy image of the tissue around the pedicle screw is more realistic, suggesting that the ideal image for clinical measurement of CT value should be reconstructed at this energy level. Single-energy imaging technology can correct artifacts to a certain extent, but can not completely eliminate artifacts.
3. The relationship between artifacts and image quality is interdependent: artifacts decrease with the increase of keV, but image contrast decreases; therefore, the relationship between image quality and artifacts should be reasonably balanced in reconstructing image selective energy level, not the higher keV, the better.
【學位授予單位】：大連醫(yī)科大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：R816.8
本文編號：2243839
[Abstract]:Objective: To evaluate the clinical value of single-energy computed tomography (single keV) in removing metal artifacts after spinal metal implantation and to evaluate the diagnostic reliability of adjacent tissues after removing the artifacts.
Materials and Methods: 35 cases of lumbar pedicle screw internal fixation in our hospital were collected. The images of 5 m 140 kVp were reconstructed by energy spectrum CT imaging (GSI) and 11 groups of single energy images were reconstructed by 10 keV interval from 40 keV to 140 keV. Twelve regions of interest (ROI) were selected in the adjacent region and one background ROI was selected to measure the CT value of each ROI, and the artifacts index (AI) of 12 ROIs around the metal was calculated. 2) The images of pedicle screw level and pedicle level of adjacent non-pedicle screw level were selected. Subjective evaluation: Two radiologists with intermediate professional titles scored 140 kVp images and 40-140 keV single-energy images by double-blind method. Scoring method: 3,2,1,0 points were scored according to the influence of artifacts on image quality. Pedicle cortex showed clearly, soft tissue contrast was good; 2 was divided into good image quality, some artifacts, metal nails and pedicle cortex showed clearly, soft tissue showed clearly; 1 was heavier artifacts, image still can be observed, metal nails and pedicle cortex showed less clearly; 0 was very heavy artifacts, image could not be observed. SPSS19.0 software was used for all statistical analysis, and P0.05 was used for statistical significance. The AI values of 12 ROIs around the screw were logarithmically analyzed by one-way ANOVA, and LSD was used for multiple comparisons. CT values of vertebral canal, psoas major muscle, and SD values were divided between pedicle screw level and pedicle level images without pedicle screw. Paired sample t test was used, subjective score was analyzed by one-way ANOVA, and LSD test was used for multiple comparisons.
Result:
1. Objective evaluation: (1) With the increase of keV, AI values gradually decreased; there was no significant difference in AI values between 90-140 keV groups near the bilateral pedicles, and no significant difference in AI values between 100-140 keV groups in the remaining regions of interest (p0.05). Compared with 140 kVp group, there was no significant difference in AI values of 70 keV and 80 keV levels outside the right pedicle, in the front of the vertebral body, in the vertebral body and behind the spinous process. There was no significant difference in AI at 70 keV level among the remaining regions of interest (p0.05). There were significant differences in AI values at other keV levels. The AI mean of 40-60 keV group was higher than that of 140 kVp group. The AI mean of 90-140 keV group was less than that of 140 kVp group. (2) The AI mean of psoas major muscle at pedicle screw level and non-pedicle screw level was higher than that of 140 kVp group. There was no significant difference in CT values between 100 and 120 keV, 120 and 140 keV (p0.05); SD values of psoas major muscle at pedicle screw level and non-pedicle screw level, SD values of spinal canal in 140 kVp images and 40 to 140 keV single energy images were statistically significant (p0.05). The absolute value of the difference decreased with the increase of keV, and the difference between 100 and 140 keV was similar.
2. Subjective evaluation: With the increase of keV, the artifacts decreased, the cortex of pedicle screw and pedicle screw showed clearer, but the contrast of surrounding tissues decreased, and the diameter of pedicle screw became thinner. There was no significant difference in subjective score between 120 and 140 keV images (p0.05); there was no significant difference in subjective score between 80 keV images and 140 kVp images (p = 0.607). There was a statistically significant difference in the subjective scores of flat single energy and 140kVp images (P0.05).
Conclusion:
1. Spectral CT single-energy imaging can effectively reduce the metal artifacts after lumbar pedicle screw fixation, and high-energy level (100-140 keV) is more effective in removing the metal implant artifacts.
2,120 keV single-energy image of the tissue around the pedicle screw is more realistic, suggesting that the ideal image for clinical measurement of CT value should be reconstructed at this energy level. Single-energy imaging technology can correct artifacts to a certain extent, but can not completely eliminate artifacts.
3. The relationship between artifacts and image quality is interdependent: artifacts decrease with the increase of keV, but image contrast decreases; therefore, the relationship between image quality and artifacts should be reasonably balanced in reconstructing image selective energy level, not the higher keV, the better.
【學位授予單位】：大連醫(yī)科大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：R816.8
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