双层探测器能谱CT虚拟单能量成像在兔VX2肝癌模型微小病灶检测中的价值
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摘要
目的评估双层探测器能谱CT虚拟单能量成像(monoE)在兔VX2肝癌模型微小病灶检测中的应用价值。方法 CT引导下穿刺建立兔VX2肝癌双瘤模型24只,建模后第5日采用双层探测器能谱CT进行扫描,分别获取常规混合能量图像和不同能级monoE图像(40、45、50、55、60、65、70、80、100 keV)。两名诊断医师盲法独立阅片,诊断是否存在病灶、病灶数量及长径测量,并与病理检查结果对比,对存在病灶的图像质量进行客观评价[信噪比(SNR)和对比噪声比(CNR)]和主观评分。结果病理证实共30个病灶建立成功,平均大小(3. 99±0. 91) mm。常规混合能量CT共检出18个病灶(47. 40%); 40、45、50、55、60、65 keV能级monoE CT均检出30个病灶(100%)。其中40 (r=0. 948,P=0. 000)、45 (r=0. 958,P=0. 000)、50 (r=0. 972,P=0. 000)、55 (r=0. 952,P=0. 000)、60 (r=0. 921,P=0. 000)、65 keV (r=0. 917,P=0. 000)能级monoE图像病灶长径测量值与新鲜病理标本长径测量值相关性优于常规混合能量图像(r=0. 206,P=0. 270)。40、45、50、55 keV能级monoE图像质量主观评分分别为4. 50 (4. 00,4. 50)(P=0. 000)、5. 00 (5. 00,5. 00)(P=0. 000)、5. 00 (4. 50,5. 00)(P=0. 000)、4. 00 (4. 00,4. 50)(P=0. 002),均明显高于常规混合能量的3. 00 (2. 50,3. 00)。图像质量客观评价结果显示,在虚拟单能量图像状态下随能级水平的升高,病灶SNR和CNR呈递减趋势;其中,40 (P=0. 000)、45 (P=0. 002)、50 keV (P=0. 011)状态下SNR明显高于混合能量图像,40 (P=0. 000)、45 (P=0. 000)、50 (P=0. 000)、55 keV (P=0. 002)状态下CNR明显高于混合能量图像。结论双层探测器能谱CT monoE图像在45～50 keV能级状态下能显著提高兔VX2肝癌模型微小病灶的检出率,同时具有较好的噪声控制和图像质量。
Objective To evaluate the value of virtual monoenergetic( mono E) using dual-layer detector spectrum CT in detecting small lesions in rabbit VX2 liver cancer models. Methods Hepatic VX2 doubletumor models were established in 24 New Zealand white rabbits by CT-guided puncture. All the rabbits underwent CT scans by using dual-layer detector CT to generate conventional 120-keV polychromatic images and monoE images with energy levels ranging from 40 to 100 keV during the arterial phase. The quantity of the lesion and measurement of the lesion length as well as the objective evaluations [signal noise ratio( SNR) and contrast noise ratio( CNR) ] and the subjective evaluations( overall image quality score) of the image quality were independently measured by two radiologists. The results were compared with pathological findings. Results Pathology confirmed that 30 lesions were successfully established,with an average size of( 3. 99 ± 0. 91) mm. Eighteen( 47. 40%) and 30( 100%) lesions were detected by conventional images and monoE images with energy levels from 40 to 65 keV,respectively. The correlation between the length diameter of fresh pathological specimens and the measurements of lesion length diameter on 40( r = 0. 948,P = 0. 000),45( r = 0. 958,P = 0. 000),50( r = 0. 972,P = 0. 000),55( r = 0. 952,P = 0. 000),60( r = 0. 921,P = 0. 000),65 ke V( r =0. 917,P = 0. 000) monoE images was better than that on conventional images( r = 0. 206,P = 0. 270). The subjective evaluation scores of the quality of the 40,45,50,and 55 keV mono E images were 4. 50( 4. 00,4. 50)( P = 0. 000),5. 00( 5. 00,5. 00)( P = 0. 000),5. 00( 4. 50,5. 00)( P = 0. 000),and 4. 00( 4. 00,4. 50)( P = 0. 002),respectively,which were significantly higher than the conventional mixed energy images [3. 00( 2. 50,3. 00) ]. The objective evaluation of image quality showed that the SNR and CNR of monoE images decreased with the increase of the energy level of the mono E image. The CNR of mono E images with 40( P = 0. 000),45( P = 0. 002),and 50 keV( P = 0. 011) were higher than that of the conventional image. The CNR of monoE images with 40( P = 0. 000),45( P = 0. 000),50( P = 0. 000),and 55 keV( P = 0. 002) were higher than that of the conventional images. Conclusion Dual-layer detector spectrum CT monoE image in the low-energy state of 45-50 keV can improve the detection rate of small lesions in rabbit hepatic VX2 tumor models with better noise control and provide better image quality compared with conventional polychromatic images.
Objective To evaluate the value of virtual monoenergetic( mono E) using dual-layer detector spectrum CT in detecting small lesions in rabbit VX2 liver cancer models. Methods Hepatic VX2 doubletumor models were established in 24 New Zealand white rabbits by CT-guided puncture. All the rabbits underwent CT scans by using dual-layer detector CT to generate conventional 120-keV polychromatic images and monoE images with energy levels ranging from 40 to 100 keV during the arterial phase. The quantity of the lesion and measurement of the lesion length as well as the objective evaluations [signal noise ratio( SNR) and contrast noise ratio( CNR) ] and the subjective evaluations( overall image quality score) of the image quality were independently measured by two radiologists. The results were compared with pathological findings. Results Pathology confirmed that 30 lesions were successfully established,with an average size of( 3. 99 ± 0. 91) mm. Eighteen( 47. 40%) and 30( 100%) lesions were detected by conventional images and monoE images with energy levels from 40 to 65 keV,respectively. The correlation between the length diameter of fresh pathological specimens and the measurements of lesion length diameter on 40( r = 0. 948,P = 0. 000),45( r = 0. 958,P = 0. 000),50( r = 0. 972,P = 0. 000),55( r = 0. 952,P = 0. 000),60( r = 0. 921,P = 0. 000),65 ke V( r =0. 917,P = 0. 000) monoE images was better than that on conventional images( r = 0. 206,P = 0. 270). The subjective evaluation scores of the quality of the 40,45,50,and 55 keV mono E images were 4. 50( 4. 00,4. 50)( P = 0. 000),5. 00( 5. 00,5. 00)( P = 0. 000),5. 00( 4. 50,5. 00)( P = 0. 000),and 4. 00( 4. 00,4. 50)( P = 0. 002),respectively,which were significantly higher than the conventional mixed energy images [3. 00( 2. 50,3. 00) ]. The objective evaluation of image quality showed that the SNR and CNR of monoE images decreased with the increase of the energy level of the mono E image. The CNR of mono E images with 40( P = 0. 000),45( P = 0. 002),and 50 keV( P = 0. 011) were higher than that of the conventional image. The CNR of monoE images with 40( P = 0. 000),45( P = 0. 000),50( P = 0. 000),and 55 keV( P = 0. 002) were higher than that of the conventional images. Conclusion Dual-layer detector spectrum CT monoE image in the low-energy state of 45-50 keV can improve the detection rate of small lesions in rabbit hepatic VX2 tumor models with better noise control and provide better image quality compared with conventional polychromatic images.
引文
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[19] Hickethier T,Baessler B,Kroeger JR,et al. Monoenergetic reconstructions for imaging of coronary artery stents using spectral detector CT:In-vitro experience and comparison to conventional images[J]. J Cardiovasc Comput Tomogr,2017,11(1):33-39. DOI:10. 1016/j. jcct. 2016. 12. 005.
[20] Lee SM,Kim SH,Ahn SJ,et al. Virtual monoenergetic dual-layer,dual-energy CT enterography:optimization of keV settings and its added value for Crohn's disease[J]. Eur Radiol,2018,28(6):2525-2534. DOI:10. 1007/s00330-017-5215-z.
[2] Chen AL,Liu AL,Wang S,et al. Detection of gallbladder stones by dual-energy spectral computed tomography imaging[J]. World J Gastroenterol,2015,21(34):9993-9998.DOI:10. 3748/wjg. v21. i34. 9993.
[3] Morgan DE. Dual-energy CT of the abdomen[J]. Abdom Imaging,2014,39(1):108-134. DOI:10. 1007/s00261-013-0033-5.
[4] McCollough CH,Leng S,Yu L,et al. Dual-and multi-energy CT:principles,technical approaches,and clinical applications[J]. Radiology,2015,276(3):637-653. DOI:10. 1148/radiol. 2015142631.
[5] Rassouli N,Etesami M,Dhanantwari A,et al. Detectorbased spectral CT with a novel dual-layer technology:principles and applications[J]. Insights Imaging,2017,8(6):589-598. DOI:10. 1007/s13244-017-0571-4.
[6] Meier A,Wurnig M,Desbiolles L,et al. Advanced virtual monoenergetic images:improving the contrast of dual-energy CT pulmonary angiography[J]. Clin Radiol, 2015, 70(11):1244-1251. DOI:10. 1016/j. crad. 2015. 06. 094.
[7] Guimaraes LS,Fletcher JG,Harmsen WS,et al. Appropriate patient selection at abdominal dual-energy CT using 80 ke V:relationship between patient size, image noise, and image quality[J]. Radiology,2010,257(3):732-742. DOI:10.1148/radiol. 10092016.
[8] Rassouli N,Chalian H,Rajiah P,et al. Assessment of70-keV virtual monoenergetic spectral images in abdominal CT imaging:A comparison study to conventional polychromatic120-kVp images[J]. Abdom Radiol(NY),2017,42(10):2579-2586. DOI:10. 1007/s00261-017-1151-2.
[9] Lv P,Lin XZ,Chen K,et al. Spectral CT in patients with small HCC:investigation of image quality and diagnostic accuracy[J]. Eur Radiol,2012,22(10):2117-2124. DOI:10. 1007/s00330-012-2485-3.
[10] Kuszyk BS,Boitnott JK,Choti MA,et al. Local tumor recurrence following hepatic cryoablation:radiologic-histopathologic correlation in a rabbit model[J]. Radiology,2000,217(2):477-486. DOI:10. 1148/radiology. 217. 2. r00nv41477.
[11] Brooks RA, Di Chiro G. Split-detector computed tomography:a preliminary report[J]. Radiology,1978,126(1):255-257. DOI:10. 1148/126. 1. 255.
[12] Faby S,Kuchenbecker S,Sawall S,et al. Performance of today's dual energy CT and future multi energy CT in virtual non-contrast imaging and in iodine quantification:A simulation study[J]. Med Phys,2015,42(7):4349-4366. DOI:10. 1118/1. 4922654.
[13] Sudarski S,Apfaltrer P,Nance JJ,et al. Optimization of keV-settings in abdominal and lower extremity dual-source dual-energy CT angiography determined with virtual monoenergetic imaging[J]. Eur J Radiol,2013,82(10):e574-e581. DOI:10. 1016/j. ejrad. 2013. 04. 040.
[14] Vlahos I,Chung R,Nair A,et al. Dual-energy CT:vascular applications[J]. AJR Am J Roentgenol,2012,199(5Suppl):S87-S97. DOI:10. 2214/AJR. 12. 9114.
[15] Marin D,Nelson RC,Samei E,et al. Hypervascular liver tumors:low tube voltage,high tube current multidetector CT during late hepatic arterial phase for detection-initial clinical experience[J]. Radiology,2009,251(3):771-779. DOI:10. 1148/radiol. 2513081330.
[16] Marin D,Boll DT,Mileto A,et al. State of the art:dualenergy CT of the abdomen[J]. Radiology,2014,271(2):327-342. DOI:10. 1148/radiol. 14131480.
[17] Martin SS,Wichmann JL,Scholtz JE,et al. Noise-optimized virtual monoenergetic dual-energy CT improves diagnostic accuracy for the detection of active arterial bleeding of the abdomen[J]. J Vasc Interv Radiol,2017,28(9):1257-1266. DOI:10. 1016/j. jvir. 2017. 06. 011.
[18] Yu L, Leng S, McCollough CH. Dual-energy CT-based monochromatic imaging[J]. AJR Am J Roentgenol,2012,199(5 Suppl):S9-S15. DOI:10. 2214/AJR. 12. 9121.
[19] Hickethier T,Baessler B,Kroeger JR,et al. Monoenergetic reconstructions for imaging of coronary artery stents using spectral detector CT:In-vitro experience and comparison to conventional images[J]. J Cardiovasc Comput Tomogr,2017,11(1):33-39. DOI:10. 1016/j. jcct. 2016. 12. 005.
[20] Lee SM,Kim SH,Ahn SJ,et al. Virtual monoenergetic dual-layer,dual-energy CT enterography:optimization of keV settings and its added value for Crohn's disease[J]. Eur Radiol,2018,28(6):2525-2534. DOI:10. 1007/s00330-017-5215-z.