CBCT图像引导鼻咽癌调强放疗的精确性研究

目的 探讨千伏级锥形束CT(kV-CBCT)图像引导技术对鼻咽癌调强放疗精确性的影响。方法 331例鼻咽癌调强放疗患者每周行kV-CBCT校正扫描。计算系统误差(Σ)和随机误差(σ),摆位扩边按照Van Herk公式计算(2.5Σ+0.7σ)。结果 分析3 972个CBCT扫描图像。校正前在x、y、z方向上的平移误差和旋转误差分别为(0.95±0.79)、(1.04±0.66)、(1.14±0.63) mm 和1.32°±0.99°、1.45°±1.37°、1.25°±1.35°,校正后分别为(0.56±0.44)、(0.56±0.51)、(0.42±0.63) mm 和0.78°±0.76°、0.62°±0.85°、0.75°±0.64°。在x、y、z方向校正前的计划靶区扩边值(MPTV)分别为2.93、3.06和3.30 mm,校正后为1.71、1.76和1.49 mm。结论 应用kV-CBCT校正鼻咽癌调强放疗摆位中的线性和旋转误差明显缩小系统和随机误差,使得MPTV缩小到2 mm以内,提高了放疗的精确性。     

慢性肾病患者低辐射低碘量冠状动脉CT成像可行性分析

目的 评估低电压、等渗低浓度和低容量碘对比剂检查方案用于慢性肾病患者冠状动脉CT成像的可行性。方法 前瞻性选取2016年7月至2018年1月南京医科大学附属常州二院共36例临床怀疑冠状动脉疾病而准备行冠状动脉成像（CTA）检查的慢性肾病患者，采用随机数表法分为对照组和观察组。对照组13例，使用常规管电压120 kV，步进-发射（step-and-shot，SAS）扫描方案，注射高浓度碘对比剂（碘普罗胺，370 mgI/ml），63~85 ml，采用传统滤波反投影法（FBP）重建。观察组23例，使用低电压SAS扫描方案，依据体质量指数（BMI）选择不同的管电压，即管电压100 kV（BMI≥25 kg/m²）或80 kV（BMI<25 kg/m²），等渗低浓度碘对比剂（碘克沙醇，270 mg I/ml），低容量注射45 ml，采用迭代重建算法。两组患者扫描时均开启自动管电流调制（4D CareDose）。两组的冠状动脉图像质量分别采用主观和客观法评价；辐射剂量以剂量长度乘积（DLP）与胸部系数k的乘积为依据计算；两组摄入的总碘量以碘浓度与注射容量的乘积计算；肾功能变化以检查前和检查后第3天的血清肌酐清除率下降百分比计算。结果 32例患者顺利完成冠状动脉CT检查，对照组和观察组的冠状动脉图像质量主观评分为（3.789±0.598）和（3.708±0.717）分，差异无统计学意义（P>0.05）；对照组和观察组左前降支（LAD）、右冠状动脉（RCA）和回旋支（LCX）平均信噪比分别为（12.88±4.53）和（13.67±2.08）、（11.9±5.0）和（12.6±5.1）、（12.78±3.15）和（13.22±3.10），两组比较差异均无统计学意义（P> 0.05）；平均对比噪声比分别为LAD（10.94±1.31）和（11.27±1.81）、RCA（10.38±1.90）和（11.01±2.26）、LCX（11.71±3.15）和（12.49±3.62），两组比较差异亦均无统计学意义（P> 0.05）。平均辐射剂量观察组比对照组降低了61.75%，分别为（1.09±0.19）和（2.85±0.59）mSv，观察组两组指标比较差异有统计学意义（t=20.260，P<0.05）。对照组与观察组的平均碘摄入量分别为（2.71±0.37）和（1.22±0.00）g，观察组降低了54.70%，两组比较差异有统计学意义（t=18.162，P<0.05）。碘对比剂注射后72 h内血清肌酐清除率观察组比对照组有所下降分别为（11.89±4.98）%和（28.75±5.24）%，差异有统计学意义（χ²=9.004，P<0.05）。结论 "三低"扫描方案可降低患者总用碘量和辐射剂量，对肾功能影响小，图像质量可满足诊断，可用于慢性肾病患者的冠状动脉成像检查。     

磁导航指导下心房颤动导管消融与手动消融辐射剂量的对比研究

目的 比较磁导航指导下心房颤动导管消融与手动消融时辐射剂量的差异.方法 连续收住入院的94例行房颤(AF)导管消融术患者,前60例为手动消融组(CON组),后34例为磁导航(MNS)指导下导管消融组(MNS组).对比两组患者的皮肤表面累积入射剂量(CD)、剂量面积乘积(DAP)、透视时间,以及医护人员的辐射剂量和透视时间.结果 MNS组和CON组两组患者的CD值分别为 (0.54±0.45)和(1.61±0.89)Gy (t=2.44,P<0.05),DAP值为(46.86±27.09)和(139.71±76.69)Gy·cm²(t=3.89,P<0.05),透视时间为(15.60±7.52)和(39.50±8.82) min (t=1.96,P<0.05).两组手术医师辐射剂量分别为(22.68±6.87)和(62.74±20.92)μSv(t=2.02,P<0.05),透视时间为(11.48±7.59)和(30.50±14.82)min(t=2.75,P<0.05),助手辐射剂量为(19.38±5.64)和(49.42±10.67)μSv(t=3.58,P<0.05)、透视时间为(8.96±5.88)和(24.49±9.09)min(t=4.20,P<0.05),护士辐射剂量为(18.98±4.99)和(47.77±13.65)μSv(t=3.17,P<0.05)、透视时间为(8.33±6.35)和(22.99±13.36)min(t=2.76,P<0.05).结论 与手动消融相比,磁导航指导下心房颤动导管消融具有明显减少医患辐射剂量的优点.     

碘对比剂对CT检查辐射生物学效应的影响

目的 评估碘对比剂对CT检查辐射效应的影响。方法 60例怀疑泌尿道系统疾病而准备行CT泌尿道造影（CTU）的患者,采用随机数表法分为对照组和试验组。对照组使用常规法CTU检查（平扫、皮质期、髓质期和排泄期）,第1次仅腹部CT平扫,3 d后补充其他3期增强扫描;试验组使用分次注射法CTU检查（平扫、实质-排泄期）,第1次行分次注射增强扫描（实质-排泄期）,3 d后补充平扫。两组患者第1次CT扫描前后10 min内各抽取外周静脉血2 ml,分离淋巴细胞,使用免疫荧光法计数外周静脉血内淋巴细胞核的γ-H2AX焦点数目。对照分析两组患者第1次扫描的辐射剂量和扫描前后外周静脉血内淋巴细胞核内γ-H2AX焦点数目的差异。结果 共50例患者顺利完成CT扫描和免疫荧光法γ-H2AX焦点数测定（对照组24例,试验组26例）,对照组和试验组患者第1次CT扫描所接受的辐射剂量分别为（4.83±1.88）和（4.55±1.66） mSv,差异无统计学意义（P>0.05）。扫描前后两组患者外周静脉血内淋巴细胞内平均γ-H2AX焦点数分别为对照组（0.06±0.02）和（1.06±0.27）个,试验组（0.06±0.03）和（1.42±0.50）个,差值为（0.97±0.23）和（1.34±0.41）个,差异有统计学意义（t=-3.25,P<0.05）,试验组焦点增多量较对照组高38.14%。试验组和对照组扫描前后不受性别影响,但受年龄（≤ 50岁和>50岁）影响,差异有统计学意义（t=-4.76、-8.16,P<0.05）。但两组患者的γ-H2AX焦点变化受性别影响差异无统计学意义（P>0.05）。结论 碘对比剂可在一定程度上增加CT辐射引起的外周血淋巴细胞DNA损伤,建议临床工作中应尽可能降低碘对比剂使用的浓度和总碘量,以降低机体的损伤。     

鼻咽癌放疗后舌骨及喉室的运动学变化特征

目的 利用视频造影吞咽检查(VFSS)分析鼻咽癌患者放疗后舌骨运动学变化特征。方法 本试验为前瞻性临床研究,收集2014年10月至2015年5月在本院初治的25例鼻咽癌患者为研究对象,在放疗前后使用普通X射线模拟机采集吞咽视频,通过视频分析软件进行连续快速截图,对比放疗前后吞咽时间、舌骨移动度及平均移动速度。结果 25例受试者放疗后平均吞咽时间较放疗前延长[(1.38±0.23)s vs.(1.12±0.26)s,t=-9.53,P<0.05),舌骨水平方向移动度(HHD) 较放疗前降低［(0.78±0.24)cm vs.(1.01±0.25)cm,t=5.82,P<0.05),舌骨垂直方向移动度(HVD) 也较放疗前降低［(0.78±0.18)cm vs.(1.01±0.25)cm,t=2.56,P<0.05],舌骨平均移动速度放疗后明显降低[(0.83±0.19)cm/s vs.(1.31±0.45)cm/s,t=6.46,P<0.05]。喉室移动度放疗前后比较,差异无统计学意义(P>0.05)。结论 鼻咽癌患者放疗后吞咽时间较前延长,舌骨移动度及平均移动速度较前降低。临床试验注册 中国临床试验注册中心,ChiCTR-OOC-16007913。     

绝对时相窄窗自适应前门控降低心律不齐冠状动脉CT成像辐射剂量的研究

目的 探讨绝对时相窄窗曝光降低心律不齐者自适应前瞻性心电门控冠状动脉CT成像辐射剂量的可行性。方法 纳入心律不齐冠状动脉CT成像检查者200例,根据随机数表法分为A、B两组,每组100例,两组均行自适应前瞻性心电门控序列冠状动脉CT扫描。A组采用绝对时相窄窗曝光(250~450 ms),B组采用相对时相宽窗曝光(30%~75%),其他扫描参数相同,两组对比剂注射方案相同,扫描完成后对图像质量进行评价并记录辐射剂量,比较两组间图像质量和辐射剂量。结果 两组的图像质量评分差异无统计学意义(P>0.05)。A组容积CT剂量指数(CTDI_vol)、剂量长度乘积(DLP)、有效剂量(E)分别为(16.71±8.35) mGy、 (231.04±114.86) mGy ·cm、(3.23±1.60) mSv,均明显低于B组的(29.35±17.90) mGy、(398.27±238.40) mGy ·cm、(5.57±3.33) mSv,差异有统计学意义(t=-6.40、-6.32、-6.32, P＜0.05)。A组中未出现重复扫描、出现1次、2次、3次重复扫描的例数分别为81、17、2和0,而B组分别为22、62、10和6例,差异有统计学意义(χ²=70.76,P＜0.05)。结论 对于心律不齐者,自适应前瞻性心电门控扫描模式,同时采用绝对时相ms扫描及重建,并且缩窄曝光时间窗,能在保证图像质量的同时降低辐射剂量。     

低浓度等渗对比剂联合低管电压在肥胖患者冠状动脉成像中的应用

目的 探讨100 kV管电压、270 mgI/ml等渗低浓度对比剂联合迭代重建算法在肥胖人群中进行冠状动脉成像(CCTA)应用的可行性。方法 将48例接受CCTA检查、体质量指数(BMI)>30 kg/m²的患者,[JP3]按随机数字表法分为对照组和试验组,每组24例。对照组使用370 mgI/ml对比剂,以常规120 kV扫描,采用传统滤过反投影法(FBP)重建图像;试验组使用270 mgI/ml对比剂,以100 kV扫描,采用第三代适应性迭代降噪算法(AIDR-3D)重建图像。两名医师对两组图像质量进行双盲法评分,比较观察者评分的一致性。比较两组患者的有效剂量(E)、平均CT值、图像噪声(N)、信噪比(SNR)、对比信噪比(CNR)、图像优良指数(FOM)和图像质量评分,以及两组患者的总碘量、碘注入率和对比剂相关不适感。结果 两组冠状动脉图像质量主观评分差异无统计学意义(P>0.05)。两名医师评分的一致性较高(Kappa=0.88, P<0.05)。两组图像平均CT值、SNR和CNR差异无统计学意义(P>0.05)。试验组的FOM明显高于对照组(t=-9.250、-8.604、-9.158、-5.341, P<0.05)。试验组E为(1.61±0.41)mSv,较对照组(3.64±1.09)mSv明显降低(t=8.373, P<0.01)。试验组总碘量以及碘注入率均低于对照组(t=7.628、8.480, P<0.01)。试验组注射对比剂热感和疼痛感的发生率低于对照组(χ²=18.70、6.25, P<0.05)。结论 在肥胖人群中,使用等渗低浓度对比剂结合低管电压冠状动脉检查可以在不降低图像质量的前提下,大幅度减低辐射剂量和碘摄入量。临床试验注册 中国临床试验注册中心,ChiCTR-DPD-15007510。     

2014年宁夏地区放射诊疗机构辐射防护监测结果分析

目的 比较容积CT剂量指数(CTDI_vol)及体型特异性剂量估算(SSDE)在估算腹部CT扫描时患者所受辐射剂量的差异。方法 采用Philips 256螺旋CT扫描仪对180例患者进行上腹部CT增强扫描,在左肾静脉主干层面测量每位患者的左右径(LAT)、前后径(AP),计算有效直径(ED),同时记录每位被检者的CTDI_vol值及体模的扫描直径,计算SSDE。将患者按照体重指数(BMI)分为3组:A组,BMI<20 kg/m²;B组,BMI介于20～24.9 kg/m²之间;C组,BMI>24.9 kg/m²。分别比较180例被检者及不同体重指数组CTDI_vol与SSDE之间的差异。结果 180例被检者CTDI_vol和SSDE分别为(9.91±2.91)和(14.01±2.82)mGy,差异有统计学意义(t=-13.354,P=0.000)。A组CTDI_vol和SSDE分别为(7.96±1.83)和(12.83±2.52)mGy ( t=-8.417,P =0.000);B组分别为(9.28±1.76)和(13.62±2.18)mGy(t=-15.051,P=0.000);C组分别为(12.19±3.65)和(15.39±3.47)mGy(t=-4.535,P=0.000)。此外,3组SSDE分别较CTDI_vol平均增加了62.83%、 47.80%和28.40%,即CTDI_vol过低估算被检者的辐射剂量,且随着体重指数的增加,CTDI_vol与SSDE之间的差值越小。结论 SSDE能够反映特定体型的被检者进行腹部CT扫描时所接受的辐射剂量。     

对比分析容积CT剂量指数与体型特异性的剂量评估在估算腹部CT扫描辐射剂量中的差异

目的 比较容积CT剂量指数(CTDI_vol)及体型特异性剂量评估(SSDE)在估算腹部CT扫描时患者所受辐射剂量的差异。方法 采用Philips 256螺旋CT扫描仪对180例患者进行上腹部CT增强扫描,在左肾静脉主干层面测量每例患者的左右径(LAT)、前后径(AP),计算有效直径(ED),同时记录每例被检者的CTDI_vol值及体模的扫描直径,计算SSDE。将患者按照体质量指数(BMI)分为3组:A组,BMI<20.0 kg/m²;B组,BMI介于20.0~24.9 kg/m²之间;C组,BMI>24.9 kg/m²。分别比较180例被检者及不同体质量指数组CTDI_vol与SSDE之间的差异。结果180例被检者CTDI_vol和SSDE分别为(9.91±2.91)和(14.01±2.82)mGy,差异有统计学意义(t=-13.354, P<0.01)。A组CTDI_vol和SSDE分别为(7.96±1.83)和(12.83±2.52)mGy (t=-8.417, P<0.01);B组分别为(9.28±1.76)和(13.62±2.18)mGy(t=-15.051,P<0.01);C组分别为(12.19±3.65)和(15.39±3.47)mGy(t=-4.535,P<0.01)。此外,3组SSDE分别较CTDI_vol平均增加了62.83%、 47.80%和28.40%,即CTDI_vol过低估算被检者的辐射剂量,且随着体质量指数的增加,CTDI_vol与SSDE之间的差值越小。结论 SSDE能够反映特定体型的被检者进行腹部CT扫描时所接受的辐射剂量。     

乳腺癌根治术后双弧VMAT与IMRT计划的剂量学比较

目的 比较乳腺癌根治术后双弧的容积旋转调强放射治疗(VMAT)与5野的静态调强放射治疗(IMRT)2种计划之间的剂量学差异,评估VMAT技术在乳腺癌根治术后的剂量学特点与应用能力.方法 选取28例乳腺癌根治术后患者(左侧10例,右侧18例),分别制定双90度弧段的VMAT与5野的IMRT 2种计划,主要的计划评估参数为靶区的肿瘤控制概率(TCP)、适形指数(CI)、均匀指数(HI)以及接受相应处方剂量水平照射体积百分比V₉₅、V₁₁₀,危及器官(OAR)评估包括患侧肺的正常组织并发症概率(NTCP)、D_mean、V₅、V₂₀、V₃₀,心脏的NTCP值、D_mean、V₂₅,健侧乳腺的D_mean、机器跳数(MU)以及治疗时间.结果 VMAT计划与IMRT计划的TCP值分别为(96±2)%、(90±2)%(t=-6.28,P<0.01);HI值分别为0.15±0.04,0.22±0.02(t=13.29,P<0.05);肿瘤位于左侧时,心脏NTCP值在VMAT计划与IMRT计划中分别为(1.0±0.12)%,(1.7±0.13)%(t=2.14,P<0.05);肿瘤位于右侧时,2种计划心脏的NTCP差异无统计学意义,平均剂量分别为(3.27±0.26)、(6.0±0.47)Gy(t=9.21, P<0.01);VMAT计划在MU少于IMRT计划(t=9.58,P<0.01),治疗时间短于IMRT计划(t=8.40,P<0.05).结论 乳腺癌根治术后,VMAT计划具有更强的临床应用能力,且表现出更优的剂量学特点.     

双源CT双能量扫描测定甲状腺碘浓度、体积及总碘含量的价值

目的探讨双源CT双能量扫描对正常甲状腺组织碘浓度、体积及总碘量测量的临床应用价值。方法采用双源CT对108例疑颈部或颈椎疾病患者进行双能量扫描,将患者分为<40岁组、40~60岁组及>60岁组,在后处理工作站中测量正常甲状腺组织的碘浓度、体积,并计算得到甲状腺总碘量,比较不同性别及不同年龄组甲状腺碘浓度、体积及碘含量有无统计学差异。结果所有患者甲状腺左、右叶碘浓度、体积及碘含量均没有统计学差异(P>0.05)。男性与女性甲状腺碘浓度、体积及总碘含量无统计学差异(P>0.05)。<40岁组与40~60岁组比较,甲状腺碘浓度及总碘含量均没有统计学差异(P>0.05);<40岁组与>60岁组比较、40~60岁组与>60岁组比较甲状腺碘浓度及总碘含量差异有统计学意义(P<0.05);甲状腺体积三组年龄间没有统计学差异(P>0.05)。结论双源CT双能量扫描可以准确测量甲状腺碘浓度及总碘含量,反应人体内碘水平,为评估甲状腺功能及诊断甲状腺疾病提供依据。     

Dual energy spectral CT imaging for the evaluation of small hepatocellular carcinoma microvascular invasion

ObjectiveTo study the clinical value of dual-energy spectral CT in the quantitative assessment of microvascular invasion of small hepatocellular carcinoma.MethodsThis study was approved by our ethics committee. 50 patients with small hepatocellular carcinoma who underwent contrast enhanced spectral CT in arterial phase (AP) and portal venous phase (VP) were enrolled. Tumour CT value and iodine concentration (IC) were measured from spectral CT images. The slope of spectral curve, normalized iodine concentration (NIC, to abdominal aorta) and ratio of IC difference between AP and VP (RIC_AP–VP: [RIC_AP–VP = (IC_AP−IC_VP)/IC_AP]) were calculated. Tumours were identified as either with or without microvascular invasion based on pathological results. Measurements were statistically compared using independent samples t test. The receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of tumours microvascular invasion assessment. The 70 keV images were used to simulate the results of conventional CT scans for comparison.Results56 small hepatocellular carcinomas were detected with 37 lesions (Group A) with microvascular invasion and 19 (Group B) without. There were significant differences in IC, NIC and slope in AP and RIC_AP–VP between Group A (2.48 ± 0.70 mg/ml, 0.23 ± 0.05, 3.39 ± 1.01 and 0.28 ± 0.16) and Group B (1.65 ± 0.47 mg/ml, 0.15 ± 0.05, 2.22 ± 0.64 and 0.03 ± 0.24) (all p < 0.05). Using 0.188 as the threshold for NIC, one could obtain an area-under-curve (AUC) of 0.87 in ROC to differentiate between tumours with and without microvascular invasion. AUC was 0.71 with CT value at 70 keV and improved to 0.81 at 40 keV.ConclusionDual-energy Spectral CT provides additional quantitative parameters than conventional CT to improve the differentiation between small hepatocellular carcinoma with and without microvascular invasion.Clinical Application/RelevanceQuantitative iodine concentration measurement in spectral CT may be used to provide a new method to improve the evaluation for small hepatocellular carcinoma microvascular invasion.     

Optimized energy of spectral coronary CT angiography for coronary plaque detection and quantification

BackgroundTo optimize spectral coronary computed tomography angiography (CTA) for quantification of coronary artery plaque components.Materials and methodsFifty-one subjects were prospectively enrolled (88.2% male) (NCT02740699). Dual energy coronary CTA was performed at 90/Sn150 kVp using a 3rd generation dual-source CT scanner (SOMATOM Force, Siemens Healthcare). Dual energy images were reconstructed with a) linear mixed blending of 90 and Sn150 kVp data, b) virtual monoenergetic algorithm from 40 to 150 keV (at 10- keV intervals), and c) noise-optimized virtual monoenergetic algorithm from 40 to 150 keV. Image noise, iodine signal-to-noise-ratio (SNR), and contrast-to-noise ratio (CNR) for calcified and non-calcified plaque were measured. Qualitative readings of image quality were performed. Semi-automated software (QAngioCT, Medis) was used to quantify coronary plaque. Linear mixed-models that account for within-subject correlation of plaques were used to compare the results.Results100–150 keV noise-optimized virtual monoenergetic images had lower image noise than linear mixed images (all P < 0.05). The highest iodine SNR was achieved in 40 keV noise-optimized virtual monoenergetic images (33.3 ± 0.6 vs 23.3 ± 0.7 for linear mixed images, P < 0.001). 40–70 keV noise-optimized virtual monoenergetic images and 70 keV virtual monoenergetic images had superior coronary plaque CNR versus linear mixed images (all P < 0.01) with a maximum improvement of 20.1% and 22.7% for calcified plaque and non-calcified plaque (38.8 ± 2.2 vs 32.3 ± 2.3 and 17.3 ± 1.3 vs 14.1 ± 1.4, respectively). Using 90/Sn150 kVp linear mixed images as a reference, the plaque quantity was similar for 70 keV noise-optimized virtual monoenergetic images whereas low keV images (e.g. 40 keV) yielded significantly higher coronary plaque volumes (all P < 0.001).ConclusionSpectral coronary CTA with low energy (40–70 keV) post-processing can improve the CNR of coronary plaque components. However, low energies (such as 40 keV) resulted in different absolute volumes of coronary plaque compared to “conventional” mixed 90/Sn150 kVp images.     

左侧乳腺癌根治术后调强放疗中剂量累加的研究

目的 通过形变配准及刚性配准进行左侧乳腺癌放疗中靶区及危及器官剂量累加的研究,探讨二者受量的变化规律。方法 回顾分析16例女性左侧乳腺癌根治术后患者,靶区包括锁上淋巴结引流区加胸壁,均采用6 MV X射线调强放疗（IMRT）。所有患者均接受定位、二程CT扫描,在定位图像（CT1）上制定放疗计划为Plan1,在二程定位图像（CT2）上制定放疗计划为Plan2。利用Velocity软件将Plan2的剂量进行刚性、形变配准到CT1剂量累加后获得Plan-rigid、Plan-deform。比较4个计划中靶区及危及器官的剂量学差异。结果 CT2比CT1的CTV体积平均缩小6.64%;形变后靶区剂量均匀性指数（HI）提高23.05%,而形变后心脏、左、右肺戴斯相似系数（DSC）均低于形变前（0.94±0.01 vs.0.89±0.05、0.96±0.01 vs.0.91±0.03、0.96±0.01 vs.0.92±0.03）,且差异均有统计学意义（Z=-3.208、-3.533、-3.535,P<0.05）;心脏及左肺各剂量-体积指标在Plan2、Plan-rigid、Plan-deform与Plan1的组间差异均无统计学意义（P>0.05）;在Plan-rigid组各剂量-体积指标均高于Plan-deform组。结论 靶区及危及器官体积、剂量-体积指标变化较小的左乳癌根治术后患者在进行放疗剂量累加时,推荐使用刚性配准,且初次调强计划的剂量-体积指标可基本反映双肺及心脏的受量情况。     

Myocardial delayed enhancement with dual-source CT: Advantages of targeted spatial frequency filtration and image averaging over half-scan reconstruction

BackgroundClinical utility of myocardial delayed-enhancement CT is currently limited because of relatively poor contrast-to-noise ratio (CNR) and artifacts. Targeted spatial-frequency filtration (TSFF) is a hybrid algorithm of half- and full-scan reconstruction that can achieve both high temporal resolution and improved stability of myocardial signal.ObjectiveThe purpose of this study was to evaluate image quality of delayed-enhancement CT using TSFF with image averaging and its reproducibility in infarct assessment in comparison with conventional half-scan reconstruction (HALF).MethodsForty patients with suspected coronary artery disease underwent delayed-enhancement CT with HALF and TSFF using dual-source CT. Two blinded readers independently determined the presence and size of delayed enhancement. Image quality, signal-to-noise ratio and CNR were assessed. The presence of delayed enhancement on CT was compared with magnetic resonance imaging in 12 patients.ResultsTSFF with averaging of 4 image stacks acquired during 1 breathhold demonstrated significantly better image quality compared with HALF. Good left ventricular lumen-myocardium contrast was consistently achieved with TSFF in patients who received iodine dose of >600mgI/kg. The signal-to-noise ratio and CNR were 11.3 ± 4.2 and 4.5 ± 1.6 by TSFF, being significantly higher than those by HALF (7.9 ± 2.9 and 3.3 ± 1.8; P < .01 for both). Interobserver reproducibility of infarct sizing was markedly improved by using TSFF instead of HALF (intraclass correlation coefficient: 0.86 vs 0.50). Agreement with magnetic resonance imaging by kappa statistics was 0.85 with TSFF and 0.74 with HALF.ConclusionsTSFF with image averaging can significantly improve image quality of delayed-enhancement CT and considerably enhances interobserver reproducibility of infarct sizing.     

Quantified dual energy computed tomography perfusion imaging using myocardial iodine concentration: Validation using CT derived myocardial blood flow and invasive fractional flow reserve in a porcine model

BackgroundMyocardial CT perfusion imaging with dual energy (DE-CTP) can produce myocardial iodine perfusion maps. This study evaluated the accuracy of first pass myocardial iodine concentration in DE-CTP compared to CT derived dynamic myocardial blood flow (MBF) to determine regional myocardial ischemia in an animal model of coronary stenosis using invasive Fractional Flow Reserve (FFR).MethodsSeven anaesthetised pigs (mean weight 51 ± 4 kg) had a graded coronary artery stenosis produced in six vessels (plus one control animal) using a methacrylate plug with FFR recorded in the target artery (ischemia = FFR<0.80). During adenosine vasodilation, dynamic myocardial CTP and DE-CTP imaging was performed. Using vendor supplied applications, matching regions of interest (ROIs) were drawn in myocardial segments supplied by the target coronary artery to compare the two techniques.ResultsFFR correlated strongly to MBF (r = 0.81) and modestly to myocardial iodine concentration (r = 0.65) and myocardial CT attenuation (r = 0.62) (p < 0.0001 each). The correlation to FFR was stronger using relative ratios (absolute value/reference value of normal segments) than absolute values for MBF (r = 0.86), myocardial iodine concentration (r = 0.80) and CT number (r = 0.79) (p < 0.0001 each). Comparing normal and ischaemic territories there were significant differences in MBF (96 ± 14 vs. 27 ± 18 ml/100 ml of tissue/min, p < 0.0001), myocardial iodine concentration (3.5 ± 1 vs. 1.0 ± 0.7 mg/ml, p < 0.0001) and myocardial CT number (89 ± 9 vs. 73 ± 14 HU, p = 0.002). Myocardial iodine concentration had 91% sensitivity and 98% specificity for detecting FFR <0.8.ConclusionQuantified myocardial iodine content from first pass DE-CTP correlates with CT derived myocardial blood flow and FFR and accurately discriminates ischemic territories in a porcine model. The accuracy and utility of myocardial iodine content in DE-CTP warrants further investigation in a clinical population with FFR as a reference standard.     

第三代双源CT低剂量扫描在新型冠状病毒肺炎筛查中的应用

目的 探讨第3代双源CT低剂量扫描模式结合迭代重建技术在新型冠状病毒肺炎筛查中的应用价值,并评价其辐射剂量。方法 回顾分析2019年12月至2020年2月在华中科技大学同济医学院进行新型冠状病毒肺炎筛查患者120例,按随机数表法分成试验组和常规组,各60例。试验组采用第3代双源CT机,Turbo Flash扫描模式,开启CARE kV,参考管电压90 kV,螺距2.0,ADMIRE算法。常规组采用128排CT机,常规螺旋扫描模式,固定管电压120 kV,螺距1.2,FBP算法。比较两组图像中主动脉、脊柱后方肌肉及皮下脂肪CT值、主动脉噪声、信噪比（SNR）、对比噪声比（CNR）,通过这些客观参数来评价图像质量,由2位高年资影像专家采用双盲法对图像质量进行主观评分,并比较两组图像的CT容积剂量指数（CTDI_vol）、剂量长度乘积（DLP）及有效剂量（E）。结果 试验组患者主动脉、脊柱后方肌肉的CT值分别为（45.38±4.77）和（53.41±8.44） HU,主动脉SNR为2.82±0.59,明显高于常规组的（39.68±6.26）、（42.66±6.32） HU和2.58±0.61（t=5.608、7.897、2.162,P<0.05）,而主动脉噪声、CNR及主观评分差异均无统计学意义（P>0.05）。试验组患者CTDI_vol、DLP、E分别为（3.09±1.02） mGy、（107.57±32.81） mGy·cm、（1.51±0.46） mSv,常规组分别为（7.00±1.80） mGy、（261.65±73.93） mGy·cm、（3.66±1.03） mSv,试验组明显低于常规组（t=-14.680、-14.756、-14.756,P <0.05）。结论 在新型冠状病毒肺炎的筛查中,使用第3代双源CT低剂量扫描模式结合迭代重建技术,在获得满足临床需求图像的同时,不仅有效地降低了辐射剂量,还提高了图像的SNR。     

Woodchuck Hepatic Anatomy and Vascular Alterations Due to Hepatocellular Carcinoma with Angiographic Atlas of the Abdomen and Pelvis

PurposeTo characterize the hepatic and abdominal angiographic anatomy of woodchucks and vascular changes associated with hepatocellular carcinoma (HCC).Materials and MethodsTwenty-nine woodchucks (23 with viral-associated HCC, 6 without) underwent multiphasic computed tomography (CT). Fourteen woodchucks (8 with HCC) also underwent diagnostic angiography. Hepatic arterial diameters were measured on the CT scans. Woodchucks were divided into 3 groups: non–tumor-bearing, largest tumor supplied by the right hepatic artery (RHA), and largest tumor supplied by the left hepatic artery (LHA). Statistical analysis with a repeated measures model was performed to determine the effects of tumor location (right, left), vessel measured (RHA, LHA), and interaction between the 2 on vessel diameter. Lobar arteries supplying HCC were compared with those that did not.ResultsCT anatomy and normal and variant vascular anatomy were defined. In woodchucks with HCC, LHA and RHA supplying tumors had mean diameters of 2.0 mm ± 0.3 and 1.6 mm ± 0.3 versus 1.5 mm ± 0.3 and 1.1 mm ± 0.2 for non–tumor-supplying arteries (P = .0002 and P < .0001), respectively. Lobar arteries supplying tumors were similarly ectatic. The right lateral lobe artery had the most profound increase in the mean diameter when supplying tumors, measuring 1.7 mm ± 0.1 versus 1.0 mm ± 0.1 in the non–tumor-supplying artery (P < .0001). There were no differences in the diameters of the aorta and celiac, common, and proper hepatic arteries between tumor- and non–tumor-bearing woodchucks. An angiographic atlas of the abdominal vessels was generated.ConclusionsHCC tumoral vasculature in woodchucks was ectatic compared with normal vasculature. This phenomenon recapitulates human HCC and may facilitate investigation of transcatheter and drug delivery therapies in an HCC animal model.