CT能谱成像定量碘基物质图对肺栓塞的诊断价值

目的 评价CT能谱成像定量碘基物质图对肺栓塞(PE)的诊断价值.方法 53例怀疑PE的患者行CT常规平扫及能谱增强扫描,并进行数据后处理,同时获得单能量肺CTA及碘基物质图像.观察肺动脉内有无栓子,记录栓子的位置、数目及栓塞程度;分析碘基物质图表现,记录肺内灌注异常的位置及数目,测量碘含量.计数资料比较采用x2检验,不同碘含量比较分别采用两样本的秩和检验及符号秩和检验.结果 33例患者的碘基物质图密度均匀,CTA未显示PE;19例患者共显示93个栓子,其中肺叶26个,肺段54个,亚段13个.51个栓子为闭塞性,42个栓子为非闭塞性.所有闭塞性栓塞均有灌注减低表现,非闭塞性栓塞中11个显示灌注降低.CTA栓子的栓塞程度与肺内有无灌注减低区差异有统计学意义(x2=39.94,P＜0.01).正常肺实质区[(1.92±0.54)g/L]与灌注减低区[(0.30±0.20)g/L]碘基物质含量差异有统计学意义(Z=-5.63,P＜0.01).PE低灌注区抗凝治疗前[(0.26±0.23)g/L]与治疗后[(0.94±0.50)g/L]的碘基物质含量差异有统计学意义(Z=-3.93,P＜0.01).结论 CT能谱成像可以为PE提供定性、定量分析,可以作为评价病变程度以及指导治疗的有效手段.     

不同碘浓度对比剂在肾脏MSCT增强扫描中的作用对比

目的:探讨300mgI/ml对比剂与400mgI/ml对比剂对肾脏MSCT多期增强扫描的强化作用。方法:将40例疑肾脏病变的患者随机分成两组,每组20例,分别行肾脏平扫及给予碘必乐300(300mg I/ml)与碘迈伦400(400mg I/ml)的多期增强MSCT扫描。在对比剂开始注射后18s、30s、80s、3~5min扫描。测量各期增强扫描腹主动脉、双肾动脉、双肾静脉、双肾皮质、双肾髓质、双肾盂、肾脏病变的CT强化值。观察上述结构的强化情况。结果:使用400mgI/ml对比剂组在18s与30s采集,所检测的血管与肾各结构强化均值与300mgI/ml对比剂组相比,差异有显著性意义(P<0.01),80s采集,肾动脉、肾静脉、肾髓质强化均值与300mgI/ml对比剂组相比,差异有显著性意义(P<0.01),3~5min采集,肾静脉与肾盂强化均值与300mgI/ml对比剂组相比,差异有显著性意义(P<0.01)。结论:高碘浓度对比剂对肾血管的显示优于标准碘浓度对比剂,并可降低对比剂用量。肾脏MSCT高碘浓度对比剂增强扫描在对比剂开始注射后30s与延时3~5min采集较合理。     

探讨宽体探测器低kVp全肾脏CT灌注成像的可行性

目的 探讨基于宽体探测器低kVp CT扫描对全肾脏灌注参数稳定性的影响。方法 回顾性搜集全肾CT灌注成像(CTP)患者80例,其中包括肾脏无病变者56例,经手术病理证实为肾透明细胞癌(ccRCC)的患者24例。按照灌注扫描参数不同将患者分为A、B两组,A组采用管电压100 kVp(n=40,含12例ccRCC),B组采用管电压80 kVp(n=40,含12例ccRCC),其余参数、灌注期相均一致。采用AW4.6工作站CT perfusion 4D软件进行分析,输入动脉选取左右肾动脉分支水平主动脉,生成肾脏及病变灌注图像。两名观察者对图像进行分析,测量正常双肾皮髓质和肿瘤的血流量(BF)、血容量(BV)、到达脉冲剩余函数峰值通过时间(T_max)、表面通透性(PS)及肿瘤对比剂平均通过时间(MTT)。分别比较两组组间双侧肾脏皮髓质和肿瘤各灌注参数及组内肿瘤与健侧肾脏皮质各灌注参数的差异。记录患者CT容积剂量指数(CTDIvol)和剂量长度乘积(DLP),计算有效辐射剂量(ED)。结果 A、B组间肾脏无病变者与ccRCC患者性别比例、年龄分布差异均无统计学意义(P均&g...     

容积穿梭80mm CT灌注成像并动态CT血管成像在肾癌诊断中的应用

目的探讨容积穿梭(VS)80mmCT灌注成像(CTP)并动态CT血管成像(CTA)在肾癌诊断中的应用价值。资料与方法 24例肾癌患者在64层螺旋CT上行VS80mmCTP检查,获得肿瘤和双肾实质血流量(BF)、血容量(BV)、平均通过时间(MTT)和表面通透性(PS)等灌注功能图像,同时获得80mm扫描覆盖范围内动态CTA图像。结果 24例肾癌患者均获得满意的80mmCTP图像和80mm动态CTA图像。CTP图像清楚显示了肾癌的灌注特征,瘤内高灌注区的BF值、BV值、PS值与同侧肾皮质比较,差异无统计学意义(P>0.05),但较对侧肾皮质显著降低(均P<0.01),MTT值与同侧肾皮质、对侧肾皮质比较,差异无统计学意义(P>0.05)。与同侧肾皮质、对侧肾皮质比较,瘤内低灌注区BF值、BV值、PS值显著降低,MTT值显著增高(均P<0.01)。肿瘤同侧肾皮质BF值、BV值、PS值显著低于对侧肾皮质(均P<0.01),MTT值差异无统计学意义(P>0.05)。CTA图像清楚显示双肾动脉和肿瘤新生血管的形态和血流动态变化。结论容积穿梭80mmCTP并动态CTA一次扫描可同时获得肾癌的血流动力学信息和肿瘤新生血管的形态学信息,有助于肾癌的诊断,是一种更为合理的扫描模式。     

双源CT双能量扫描在肝脏病变中的应用价值

目的 探讨双源CT(DSCT)双能量扫描对肝脏病变的诊断价值及限度.方法 将53例B超拟诊肝脏占位患者行上腹部普通平扫(TNE)及三期增强扫描(动脉期、双能量门静脉、延迟期).双能量扫描后自动生成80 kV、140 kV以及120 kV加权图像.数据导入工作站的虚拟平扫(VNE).从图像定性评估(肿瘤可见度、图像噪声、诊断接受度)及定量数值(脏器平均CT值、图像噪声、对比噪声比)比较VNE与TNE的图像质量;判断VNE能否取代TVE、80 kV图像中病变的微小血供、双能量纯(彩)碘图、以及感兴趣区(ROI)分解CT值的诊断作用.最后,对比TNE与VNE的有效辐射剂量.结果 53例中有7例在80 kV中较140 kV及120 kV加权图像更清晰显示肿瘤内血管.VNE肿瘤可见度、诊断接受性显著低于、噪声显著高于TNE(P<0.05).TNE及VNE平均CT值分别为:肝实质(58.5±5.6) HU、(58.2±6.7) HU(P=0.226);肝占位(38.8±8.1) HU、(37.4±8.3) HU(P<0.05).VNE图像噪声及对比噪声比显著高于TNE(P<0.001).超出的肝边缘及伪影对诊断无影响,除4例外,VNE均能取代TVE.纯(彩)碘图直观展示病变血供范围及程度,ROI可分解平扫及碘增强的CT值.TNE与VNE有效剂量:(3.38±0.55) mSv,(3.36±0.90) mSv(P>0.05).结论 双源CT双能量80 kV较常规CT对病变血供更敏感,其后处理功能对病变定性诊断有一定作用.VNE图像质量较TNE差,但可取代之并减少辐射剂量.     

肺部肿块性病变的能谱CT诊断价值

目的:探讨能谱CT成像对肺部肿块性病变的诊断与鉴别诊断价值。方法:回顾性分析59例肺部肿块患者的临床及影像资料,其中良性肿块22例,恶性37例。患者均行能谱CT扫描,得到动脉期和静脉期能谱曲线40~140keV区间能量水平的CT值及碘基图、水基图,并行数据分析。结果:动脉期和静脉期40~140keV能量水平CT值中,40~80keV区间的CT值良性肿块组均低于恶性肿块组,单能量越低时CT值差别越大;动脉期和静脉期碘基图上良性肿块组的碘浓度均低于恶性肿块组,差异有统计学意义(P0.05);动脉期和静脉期良性肿块组和恶性肿块组的水基值相比,差异无统计学意义(P0.05)。结论:不同性质肺部肿块在能谱成像上碘含量不同,可用以初步区分肺部良性和恶性肿块病变。     

100kVp条件下碘克沙醇(270mgI/mL)应用于主动脉CTA检查的可行性研究

目的：探讨100kVp条件下碘克沙醇（270mgI／mL）应用于主动脉CTA检查的可行性。方法：临床疑诊主动脉病变而行主动脉CTA检查的连续21例患者,分为两组,分别采用不同的CT扫描方案：A组10例,采用管电压120kVp,对比剂为碘帕醇（370mgI／mL）;B组共11例,采用管电压100kVP,对比剂为碘克沙醇（270mgI／mL）。采用两独立样本t检验（非正态分布采用Mann-WhitneyU检验）来比较两组的临床资料、CT辐射剂量、图像质量主、客观评价指标。结果：两组患者的性别、年龄和身体质量指数（BMI）的差异均无统计学意义（P=0．132、0．151和0．814）。两组的CT辐射剂量差异亦无统计学意义（P〉0．05）。B组患者接受碘的剂量明显低于A组,且差异有高度统计学意义（P〈O．001）。两组图像主观评分的差异无统计学意义（P=0．898）。图像的客观评分：两组的主动脉主干及其主要分支的CT值均〉300Hu,差异无统计学意义（P〉0．05）;A组CNR优于B组,2组差异有高度统计学意义（P=0．002）。结论：使用100kVp、碘克沙醇（270mgI／mL）进行主动脉CTA检查可以满足临床诊断需要。     

腹部增强能谱CT成像在肾功能不全患者低剂量对比剂扫描中的应用价值

目的 探讨腹部增强能谱CT成像在肾功能不全患者低剂量对比剂扫描中的应用价值.方法 前瞻性收集因病情需要行腹部增强CT扫描的100例患者纳入研究.根据检查方式将患者分为能谱扫描组和常规扫描组,并根据患者肾功能和对比剂碘含量将能谱扫描组患者分成3个亚组.其中常规扫描组46例,患者肾小球滤过率(eGFR) ＞50 ml· min-1·1.73 m-2,管电压120 kVp,对比剂用量为含碘600 mg/kg.能谱扫描组54例,其中亚组1患者10例,eGFR为30～ 39 ml·min-1·1.73 m-2,对比剂用量为含碘300mg/kg;亚组2患者25例,eGFR为40～ 50 ml· min-·1.73 m-2,对比剂用量为含碘450mg/kg;亚组3患者19例,eGFR＞50 ml· min-1·1.73m-2,对比剂用量为含碘600 mg/kg.所有患者均行腹部CT双期扫描.以腹主动脉、胰腺、肝脏、脾脏作为研究对象,竖脊肌为背景.计算与常规扫描组CT增强值相当的单能量图像水平、对比噪声比(CNR)、最佳CNR单能量水平及其CT增强值和CNR.常规扫描组与能谱扫描各亚组之间不同部位CT增强值及CNR的比较采用独立样本t检验.结果 针对不同肾功能水平的患者,采用300 mg/kg对比剂方案、能谱扫描,动脉晚期选择53 keV单能量图像[腹主动脉CT增强值为(314±70) HU,CNR为20.0±5.6;胰腺CT增强值为(85±11)HU,CNR为4.0±0.8],肝实质期选择54～ 57 keV单能量图像[肝脏CT增强值为(43±6)HU,CNR为3.0±0.9;脾脏CT增强值为(68±8)HU,CNR为3.8±1.6],能够获得与常规扫描相当的增强效果和CNR.常规扫描组腹主动脉、胰腺、肝脏和脾脏的CT增强值分别为(285±60)、(86±15)、(50±11)和(66±11)HU,CNR分别为19.7±5.0、5.1±1.4、3.3±0.8和3.5±1.0,差异均无统计学意义(P均＞0.05).采用450 mg/kg对比剂方案、能谱扫描,63 ～ 65 keV单能量范围图像与常规成像CT增强值相当,腹主动脉、胰腺、肝脏和脾脏单能量图像CNR分别为29.1±7.4、6.2±2.3、4.3±1.3和4.7±1.7,常规扫描图像CNR分别为19.7±5.0、5.1±1.4、3.3±0.8和3.5±1.0,差异均有统计学意义(P均＜0.05).采用600 mg/kg对比剂方案、能谱扫描,72～73 keV单能量图像CT增强值与常规成像相当,其CNR高于常规成像组(P均＜0.05).动脉晚期和肝实质期选择最佳CNR单能量或CT增强值相当的单能量水平,可以获得更高的CT增强值和(或)CNR.结论 采用能谱CT单能量成像技术、对肾功能不全患者腹部增强CT减少50％的碘对比剂使用剂量是可行的.与常规成像方案相比,75％碘量的对比剂方案能谱成像可以根据临床需要,在获得相当增强效果的同时可以提高图像CNR,或选择最佳CNR单能量图像,同时提高图像的增强效果和CNR.     

SPECT/CT直接测量肾脏深度在肾小球滤过率测定中的应用

目的 探讨在以SPECT/CT测定GFR时用CT直接测量肾脏深度代替传统的Tonnesen公式法的必要性和可行性.方法 49例患者在接受肾动态显像的同时进行腹部CT平扫,测量两侧肾的深度.将所测值与传统的Tonnesen公式值和SPECT侧位平面图像测量值进行比较,然后将CT和SPECT测得的肾脏深度数据代入到Gates法GFR测量软件中,观察肾脏深度改变对GFR测定值的影响.采用配对t检验对Tonnesen公式法和SPECT测量法测得的肾脏深度值及各自深度值对应的GFR与CT法测得的相关数据间差异进行比较,对Tonnesen公式误差、SPECT测量误差与肾脏深度的关系采用直线相关分析.结果 CT测得的肾脏深度分别为右肾(7.04±1.15) cm,左肾(7.18±1.15) cm.与CT测量值相比,Tonnesen公式法低估了肾脏深度[右肾:(5.77±0.90) cm,t=- 11.50,P＜0.01;左肾:(5.74±0.88) cm,t=12.20,P＜0.01],而SPECT测量值则高估了肾脏深度[右肾:(7.40±1.15) cm,t=5.19,P＜0.01;左肾:(7.49±1.19) cm,=5.14,P＜0.01].Tonnesen公式法误差与肾脏深度呈正相关(右肾:r =0.62,P＜0.01;左肾:r=0.73,P＜0.01),而SPECT测量误差与肾脏深度不相关(右肾r =0.26,P＞0.05;左肾r=0.38,P＜0.01).Tonnesen公式法得到的两侧肾脏深度差为0.03 ～0.05 cm,而SPECT和CT得到两侧肾脏深度差分别为0.54±0.33(0.01～1.28) cm和0.62±0.45(0.01～1.60) cm.Gates法采用Tonnesen公式肾脏深度低估了GFR,与CT所测肾脏深度对应的GFR相比,误差百分比分别为右肾(-20.92±11.28)％(t=-6.99,P＜0.01),左肾(-23.71±7.71)％(t=-8.73,P＜0.01);采用SPECT测量则高估了GFR,对应误差百分比为右肾(5.23±9.64)％(t=2.72,P＜0.01),左肾(8.93±9.29)％(=5.21,P＜0.01).结论 采用SPECT/CT的CT功能精确测量两侧肾脏深度,有助于提高Gates法GFR测定的准确性.     

CT脑灌注成像在基底节区腔隙性脑梗死的初步应用

目的 探讨CT脑灌注成像在基底节区腔隙性脑梗死的应用价值.资料与方法 对35例超早期(发病＜6 h)基底节区腔隙性脑梗死患者行常规CT头颅平扫及CT脑灌注成像.在常规轴位CT扫描后选取基底节区层面,经肘静脉团注45 ml非离子型对比剂,同时开始持续40 s的单层连续动态扫描,重组的40幅动态图像使用CT脑灌注软件进行处理,获得灌注图像.测量双侧基底节区感兴趣区的局部脑血流量(CBF)及局部灌注达峰时间(TTP),并进行定量分析.结果 35例基底节区腔隙性脑梗死患者中有29例被后期追踪CT或MRI证实为基底节区腔隙性脑梗死,其中20例梗死灶直径＞5 mm(＜20 mm),9例病灶＜5 mm;余6例CT复查为阴性而临床诊断为脑梗死.20例梗死灶直径＞5 mm(＜20 mm)中有17例CT灌注为阳性,表现为CBF明显低于正常侧,TTP明显长于正常侧;另外3例未发现灌注异常区.20例梗死灶直径＞5 mm(＜20 mm)患者患侧及对侧的局部灌注平均CBF分别为(384.9±118.7)ml·min-1·L-1和(256.2±80.3)ml·min-1·L-1,两者比较差异有统计学意义(t=5.898,P＜0.01);患侧及对侧的局部平均TTP分别为(12.8±3.4)s和(9.6±3.8)s,双侧对比差异亦有统计学意义(t=7.104,P＜0.01).9例病灶＜5 mm患者中,仅2例CT灌注为阳性,患侧及对侧局部灌注平均CBF分别为(448.0±137.8)ml·min-1·L-1和(422.2±229.6)ml·min-1·L-1,两者比较差异无统计学意义(t=0.664,P＞0.5);患侧及对侧局部平均TTP分别为(10.1±2.0)s和(9.3±1.3),两侧之间差异无统计学意义(t=1.039,P＞0.5).结论 CT脑灌注成像能为基底节区腔隙性脑梗死提供有价值的脑血流动力学信息,为临床超早期诊断和治疗提供依据.     

The utilization of dual source CT in imaging of polytrauma

Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner.     

Comparison of dual photon and dual energy X-ray bone densitometers in a clinic setting

In clinical practice, decisions must be made about whether and how to convert to newer technologies. To address this issue, two separate studies were conducted. We evaluated the relationships between results of lumbar spine measurements using two dual photon absorptiometry (DPA1 and DPA2) instruments and one dual energy X-ray (DXA) instrument with the same subjects (49 volunteers), and also in 65 patients who were measured on the DPA1 and DXA machines. Second, we measured the lumbar spine and the proximal femur in three groups of 12 female volunteers three times on one instrument within 1 week. We purposely simulated a busy clinic setting with different technologists, older radioactive sources, and a heterogeneous patient group. The comparison study indicated a significant difference between the mean bone density values reported by the machines, but the results were highly correlated (R ² = 0.89–0.96). The short-term precision errors (coefficients of variation) differed among the instruments, ranging from 1.3% (DXA of the spine) to 5.1% (DPA1 of the spine), and in the femoral neck, 2.3% and 2.4% (DXA and DPA1, respectively) versus 3.5% by DPA2. This study emphasizes the differences between instruments, the potential for greater error in busy clinic environments, and the apparent superiority of dual energy X-ray absorptiometry under these less than ideal conditions.     

Comparative study of the performances of X-ray and gadolinium 153 bone densitometers at the level of the spine,femoral neck and femoral shaft

We investigated the precision of gadolinium 153 dual photon absorptiometry (DPA) and quantitative digital radiography (QDR) bone densitometers by determining in vitro and in vivo coefficients of variation (CV) of bone mineral density (BMD). In vitro, the long-term CV of spine phantom BMD measured weekly for 40 weeks was 1.2% and 0.7% for DPA and QDR, respectively. Simulating soft-tissue thickness with water, the CV of 6 repeat measurements of spine phantom at depths from 0 to 27 cm in 1 cm steps (a total of 168 measurements) increased from 0.1 % at 0 cm of water to 2.5% at 27 cm for DPA, and from 0.2% at 0 cm to 1.4% at 27 cm for QDR; mean CV of the 28 series (0–27 cm) was higher for DPA (1.2%±0.8%, mean±SD) than for QDR (0.7%±0.6%;P<0.001). With the hip phantom, femoral neck BMD was determined, and the CV was also dependent on water thickness; mean CV of the 20 series (0–10 cm) was 2.1%±1.2% for DPA and 1.3%±0.9% for QDR (not significant). In vivo, at the spine level, with DPA, mean CV of BMD measured 6 times after repositioning in 6 healthy volunteers was 3.8%±1.9% and 2.1%±0.7% with¹⁵³Gd activity of 0.46Ci and 1 Ci, respectively (BMD range: 0.796 1.247 g/cm², no significant difference between the two groups). Both values were significantly higher (P < 0.05) than mean CV with QDR: 1.0%±0.5% (12 subjects, same conditions; BMD range: 0.811–1.124 g/cm², no significant difference with the two previous groups). At the femoral neck and shaft levels, the mean CV observed with QDR tended to be lower as compared with DPA (not significant). At the three sites, BMD values obtained with DPA and QDR in 62 patients were highly correlated. In conclusion, our results indicate that the higher precision obtained with QDR is particularly significant at the lumbar spine level, but large biological variations in soft tissue thickness can still influence the degree of precision of BMD measurement.     

低剂量与常规剂量对比剂双能量肺灌注图像质量对比分析

目的:探讨对比剂剂量对双源CT双能量肺灌注成像质量的影响.方法:疑肺动脉栓塞患者行双源CT双能量肺灌注扫描,30例使用低剂量(0.7ml/kg)对比剂,30例使用常规剂量对比剂(1.5ml/kg),注射速率均为4.5ml/s.扫描后同时获得肺动脉CTA及肺灌注图像.测量左、右叶肺动脉干及各肺叶动脉增强后的CT值,对比分析两组间增强后的CT值.判断肺灌注图像质量并分级,比较两组的肺灌注图像质量差异.结果:低剂量组与常规剂量组左、右叶肺动脉干及各肺叶动脉增强后的CT值无明显差异(P＞0.05).肺段及亚段肺动脉图像清晰显示.低剂量组肺灌注图像大部分信号均匀(26/30),常规剂量组肺灌注图像大部分信号均匀(24/30).常规剂量组上腔静脉、右心房高密度对比剂所致灌注伪影明显多于低剂量组(48:10).结论:低剂量与常规剂量双能量肺灌注成像的肺动脉图像质量无明显差异,降低对比剂剂量可以减少双能量肺灌注图像的伪影.     

Virtual unenhanced second generation dual-source CT of the liver: Is it time to discard the conventional unenhanced phase?

Introduction

Dual-energy dual source CT can almost simultaneously image patients using two different tube potentials, allowing material decomposition and creation of ‘virtual unenhanced’ (VU) images from post-contrast series.

Methods

75 patients undergoing triple-phase liver CT examinations were imaged using a second generation dual-source CT machine with tube potentials 140/100 kVp. Post-processing VU series were derived from arterial and portal phases. Regions-of-interest from liver parenchyma and within fat (‘noise’ assessment) were drawn to compare VU series to conventional unenhanced (CU) series. Subjective analysis assessed image quality and the suitability of VU to replace CU series.

Results

Mean Hounsfield unit (HU) values of liver were higher in the VU series: portal 51.9 (SD = 10.29), arterial 51.1 (SD = 10.05), compared to the CU series 49.2 (SD = 9.11); P < 0.001. However, Pearson's correlation of the VU and CU series remained excellent: 0.838 (portal), 0.831 (arterial). Bland–Altman plots also showed good agreement between both VU and the CU datasets. Noise measurements were significantly lower in both VU series (P < 0.001). For subjective analysis, image quality was rated as very good/excellent in 100% of CU images, 93.3% of portal VU and 88.7% of arterial VU series. Overall, portal VU and arterial VU images were acceptable replacements for the CU series in 97.4% and 96.1%, respectively. Post-processing was noted to create a number of artefacts in VU images – knowledge of these is essential for interpretation.

Conclusions

Portal and arterial-derived VU images objectively correlate to CU images and demonstrate good image quality and acceptability. VU image sets could replace the conventional unenhanced images in the vast majority of cases, significantly reducing radiation dose.     

Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

Objectives

Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts.

Materials and methods

Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference.

Results

Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries.

Conclusions

Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.     

Adenosine-stress dynamic real-time myocardial perfusion CT and adenosine-stress first-pass dual-energy myocardial perfusion CT for the assessment of acute chest pain: Initial results

Purpose

Recent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain.

Methods and materials

Myocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65 ± 8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel “shuttle” mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT.

Results

In Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments.

Conclusion

Our results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.     

低剂量对比剂双能量肺灌注成像评估肺动脉内血栓与灌注缺损间的关系

目的:应用双源CT低剂量对比剂双能量肺灌注成像评估急性肺动脉栓塞患者血管内血栓与肺灌注缺损间的关系,以提高对肺动脉栓塞诊断的准确性。方法:随机选择无肺动脉栓塞患者的低剂量与常规剂量双能量肺灌注成像各15例,对比分析其图像质量;收集20例疑肺动脉栓塞患者行低剂量双能量肺灌注成像;同时获得肺动脉CTA及肺灌注图像。分析肺动脉内有无血栓,以及血栓的部位、数量及形态特征。用双能量肺灌注分析软件判断有无灌注缺损及缺损的部位、形态及范围。对比分析并统计肺动脉内血栓与肺灌注缺损间的关系。结果:肺动脉栓塞患者的低剂量与常规剂量双能量肺灌注成像质量无明显差异(P>0.05)。20例疑似病例中,15例诊断为肺动脉栓塞,其中13例患者肺灌注图像中出现102个肺叶、肺段、或亚段灌注缺损,4例共6个灌注缺损CTA无明确血栓;11例肺动脉CTA显示43个血栓,其中9例血栓与灌注缺损同时存在,2例CTA共5个血栓肺内无灌注缺损。75个灌注缺损与栓塞肺动脉供血范围一致,21个灌注缺损(8段、13亚段)与肺动脉供血范围无关。结论:综合分析双源CT低剂量双能量肺灌注图与CTPA,可以提高肺动脉栓塞诊断的准确性。