不同体位SPECT心肌灌注显像对左心室下后壁图像的影响

在SPECT MPI中,由于膈肌衰减引起的左心室下后壁稀疏、缺损是最常见的图像伪影之一.本研究通过比较不同显像体位之间左心室下后壁图像质量及定量计算结果的差异,探讨不同显像体位对左心室下后壁图像的影响,现报道如下.     

不同体位对相对运动错觉诱发运动病的影响

目的观察体位因素对转鼓诱发的相对运动错觉导致的运动病症状是否有影响。方法采用可以变换体位的转鼓作为诱发相对运动错觉进而诱发运动病的装置，对24名健康受试者进行试验。采用恶心评定量表和恶心问卷作为测评工具，观察受试者在不同体位情况下运动病的症状程度和旋转耐受时间是否存在差别。结果卧位体位时旋转后即刻恶心问卷中的消化道不适得分明显高于坐位时的得分，差异有显著性意义（P〈0．01）。卧位时受试者的旋转耐受时间较坐位时短，但差异没有达到统计学显著性水平（P〉0．05）。男性受试者在旋转后即刻、旋转后15min、旋转后30min恶心评定量表得分均高于女性受试者，差异有显著性意义（P〈0．05或P〈0．01）。结论不同体位对相对运动错觉诱发的运动病症状有影响。     

正常肺叶不同体位呼吸气薄层螺旋CT观察

目的探讨呼气相CT上肺内低密度区产生的原因。方法15例正常青年志愿者,年龄21~23岁,平均22岁。在右中肺门区,做仰卧与俯卧位深吸气屏气及深呼气屏气薄层螺旋CT扫描。对仰卧及俯卧位呼吸气相上中肺门区解剖结构相同的层面,进行肺叶面积及密度测量。计算肺叶吸气较呼气面积增加百分率及密度增加值。结果当右下叶处于下垂位,同层面肺叶膨胀性及密度改变均大于非下垂位,肺叶膨胀性与密度变化呈现高度相关(P<0.005)。结论呼气CT上肺内低密度区产生的因素有多种,其中肺内血流变化可直接影响肺密度,同时对肺叶膨胀性也有一定影响。     

不同体位颈椎MRI对平山病的影像诊断

目的 探讨平山病患者自然位和前屈位颈椎MRI表现及其诊断价值.资料与方法 对6例经临床确诊的平山病患者及6名正常自愿者均行颈椎自然位+前屈位+增强MRI,对比分析平山病患者低位颈髓的MRI表现.结果 自然位:6例患者颈椎生理曲度变直,低位颈髓变细;6名正常自愿者可见颈膨大(约脊髓C6～T2段).前屈位:6例患者低位颈髓变扁、萎缩,两种体位低位颈髓前后径差值与正常自愿者相比差异有统计学意义(P<0.05),另可见背侧硬膜囊后壁前移、硬膜外间隙增宽,内见迂曲、条形流空信号,增强后明显强化;正常自愿者低位颈髓较自然位略变细,背侧硬膜囊无前移、扩张,其内未见流空信号.结论 不同体位MRI均能显示平山病患者颈椎的异常表现,尤其是前屈位对平山病的诊断具有重要价值.     

不同体位心电图ST-T改变分析

目的观察分析不同体位常规12导联心电图ST-T的变化,探讨其临床意义。方法随机选择了40例体检者,分别进行平卧位、左侧卧位、右侧卧位、坐位、站立位,常规12导联心电图检查,对每例心电图以平卧位为标准进行对比分析ST-T的变化。结果各体位心电图中ST段无明显变化,只有1例常规平卧心电图STⅡⅢavFV4～V6水平压低0.05～0.075mV,而左侧卧位心电图STⅡⅢavFV4～V6呈下斜型压低0.05～0.10mV。T波的变化下壁变化明显T波由直立转为低平浅倒,高侧壁前外侧壁由直立略低平转为低平平坦。结论体位性ST-T改变是一种正常的变异[1]。     

基于不同体质量指数CT尿路成像辐射剂量控制

目的 探讨不同体质量指数患者CT尿路成像扫描参数优化及辐射剂量控制措施。方法 按常规参数（3种体型均120 kV,CARE Dose4D）、低kV[体质量指数（BMI）≤22.9：80 kV、22.9 < BMI < 30∶100 kV、BMI≥30∶120 kV,CARE Dose4D]、低mAs（120 kV,3种体型均在CARE Dose4D基础上mAs降低40%）3种扫描方式前瞻性收集CT尿路成像检查133例,测量各组图像噪声、信噪比（SNR）及对比噪声比（CNR）作为图像质量客观评价指标,主观评价由两名具有5年以上工作经验医师采用双盲法进行5分制评价。记录各组患者CT剂量报告中的容积CT剂量指数（CTDI_vol）、剂量长度乘积（DLP）,计算有效剂量（E）。结果 80、100 kV扫描患者的有效剂量下降了77.7%、38.3%,差异有统计学意义（Z=-3.330、-5.595,P<0.05）;80 kV扫描与常规扫描之间肾皮质的噪声、SNR、CNR及输尿管噪声差异有统计学意义（Z=-3.705~-2.392,P<0.05）,但输尿管的SNR、CNR及肾盂的噪声、SNR、CNR差异无统计学意义（P>0.05）,100 kV扫描与常规扫描之间肾皮质的噪声、SNR差异有统计学意义（Z=-5.096、-3.566,P<0.05）,但肾皮质的CNR及肾盂、输尿管的噪声、SNR、CNR差异无统计学意义（P>0.05）。3种体型低mAs扫描的有效剂量较常规扫描分别下降了38.3%、32.0%、34.7%,差异有统计学意义（Z=-5.086、-5.912、-2.842,P<0.05）,22.9Z=-2.587,P<0.05）,其余肾皮质、肾盂、输尿管的噪声、SNR、CNR差异均无统计学意义（P>0.05）;图像主观评价评分均>3分。结论 针对不同体质量指数患者所采用的低kV、低mAs扫描方案可以有效降低患者的辐射剂量,并能达到临床诊断要求。     

双能量CT Moidal非线性图像融合技术对CT图像质量的影响

目的 比较双能量CT线性融合与Moidal非线性融合图像处理技术的差别,评价二者对CT图像质量的影响.方法 将5支试管装有不同浓度的碘对比剂溶液(16.3、26.4、48.7、74.6和112.3 HU),嵌入新鲜猪肝制成模型.扫描后由双能量扫描模式自动生成线性融合图像,Syngo工作站双能量优化对比软件重组获得Moidal非线性融合图像.按120 kV、线性融合、Moidal非线性融合分3组,分别测量并计算各组对比信噪比,采用one-wayANOVA法比较组间优良指数值差别.选取临床20例腹部双源CT扫描患者图像,分别测量并计算肝脏、肾皮质、脾脏、胰腺以及腹主动脉的信噪比,采用独立样本t检验比较线性融合与Moidal非线性融合组差别.2名观察者盲法评价2组图像各器官醒目度.结果 实验CT值为16.3、26.4、48.7、74.6和112.3 HU时,Moidal非线性融合组图像的优良指数值分别为20.65±8.18、11.40±4.25、1.60±0.82、2.40±1.13、45.49±17.86.在74.6、112.3 HU时,Moidal非线性融合组与线性融合组(分别为0.30±0.06、14.43±4.59)、120 kV组(分别为0.22±0.05、15.31±5.16)比较差异均有统计学意义,Moidal非线性融合组优良指数更高(P＜0.05).患者实质脏器比较中,Moidal非线性融合组肾实质、腹主动脉信噪比分别为19.2±5.1和36.5±13.9,线性融合组分别为12.4±3.8和22.6±7.0,差异有统计学意义(P＜0.05).2名观察者对Moidal非线性融合组各器官醒目度评分高于线性融合法(Kappa=0.64),两者一致性较好.结论 Moidal非线性融合法在提高图像信噪比、增加主观醒目度等方面明显优于线性融合法.

Abstract：

Objective To compare the difference between linear blending and non-linear blending function for dual-energy CT, and to evaluate the effect on CT image quality. Methods The model was made of a piece of fresh pork liver inserted with 5 syringes containing various concentrations of iodine solutions ( 16.3,26.4,48.7,74.6 and 112.3 HU). Linear blending images were automatically reformatted after the model was scanned in the dual-energy mode. Non-linear blending images were reformatted using the software of optimal contrast in Syngo workstation. Images were divided into 3 groups, including linear blending group, non-linear blending group and 120 kV group. Contrast noise ratio (CNR) were measured and calculated respectively in the 3 groups and the different figure of merit (FOM) values between the groups were compared using one-way ANOVA. Twenty patients scanned in the dual-energy mode were randomly selected and the SNR of their liver, renal cortex, spleen, pancreas and abdominal aorta were measured. The independent sample t test was used to compare the difference of signal to noise ratio (SNR) between linear blending group and non linear blending group. Two readers' agreement score and single-blind method were used to investigate the conspicuity difference between linear blending group and non linear blending group.Results With models of different CT values, the FOM values in non-linear blending group were 20. 65 ±8.18,11.40±4.25, 1.60±0.82,2.40±1.13, 45.49±17. 86. In 74. 6 HU and 112. 3 HU models, the differences of the FOM values observed among the three groups were statistically significant ( P＜0.05),which were 0.30±0. 06 and 14. 43 ±4. 59 for linear blending group, and 0. 22 ±0. 05 and 15.31±5.16 for 120 kV group. And non-linear blending group had a better FOM value. The SNR of renal cortex and abdominal aorta were 19.2±5.1 and 36. 5 ± 13.9 for non-linear blending group, while they were 12.4 ±3.8 and 22.6±7.0 for linear blending group. There were statistically significant differences between the two groups. The conspicuity scores of different organs in non linear blending group were far higher than those in the linear bending group. The Kappa value was 0. 64, showing good consistency. Conclusion Compared to the linear blending method, the non-linear blending method was a better option, especially in improving SNR and conspicuity.     

肩关节镜术后苏醒期不同体位对呼吸功能的影响

目的：评价苏醒期不同体位对肩关节镜全身麻醉联合肌间沟臂丛神经阻滞患者呼吸功能的影响。方法：选择行关节镜下冈上肌腱缝合术患者70例,采用随机数字表法将患者分为两组：平卧位组和头高30°组。两组患者在麻醉前取平卧位,B超下采集膈肌移动度作为基线。术后平卧位组拔除气管插管入麻醉苏醒室后即刻进行血气分析,常规面罩吸氧,监测心率、呼吸、无创动脉血压和血氧饱和度,体表加温,记录生命体征。头高30°组在进入麻醉苏醒室将床头抬高30°后再进行同样护理操作。比较两组入麻醉苏醒室后即刻、脱氧5分钟和脱氧15分钟的血气分析指标：氧分压(PaO₂)、二氧化碳分压(PaCO₂)、经皮血氧饱和度(SpO₂);神经阻滞前(术前)及苏醒期(患者离开麻醉苏醒室前)两时刻深呼吸状态下的膈肌移动度;不良反应发生情况,如低氧血症、憋气、舌后坠等。结果：与平卧位组相比,抬高床头30°组在术后苏醒期脱氧15分钟的PaO₂、SpO₂明显升高(P<0.05),深呼吸时膈肌移动度明显增大(P<0.05),术后憋气、...     

在16排螺旋CT头颈部血管成像中不同注射流率对影像质量影响的比较研究

目的探讨高压注射器在16排螺旋CT头颈部血管成像中的参数应用。方法对60例头颈部CT血管成像(CTA)患者,采用3 ml/s、4 ml/s两组的注射流率、总量、扫描延迟时间及注射方式,根据原始图像和最大强度投影(MIP)重建像作综合性评价。结果选择合适的注射参数,优片率平均达到82%,影像良占17%,影像差占1%,颈动脉、椎动脉及颅内动脉在两组中均清晰显示,显示程度评分上两组间无统计学差异(P>0.05)。结论选择合理的高压注射器的注射流率、总量、扫描延迟时间及注射方式,可获得满意的增强效果,为诊断提供重要依据。     

双源CT扫描模式对头颈部辐射剂量和影像质量的影响

目的 探讨头颈部CT扫描中,不同扫描模式对辐射剂量和影像质量的影响程度。方法 利用头颈部仿真模体和双源CT,分别使用固定扫描条件120 kV和200 mAs,以及自动管电流调制技术（CARE Dose 4D）、自动管电压调制技术（CARE kV）和部分角度扫描模式（X-CARE）的组合进行成像,分别为120 kV+200 mAs、120 kV+200 mAs+X-CARE、CARE Dose 4D+120 kV、CARE Dose 4D+120 kV+X-CARE、CARE Dose 4D+CARE kV、CARE Dose 4D+CARE kV+X-CARE 6种扫描模式。每次扫描均使用两片热释光剂量片（TLD）分别测量眼晶状体和甲状腺的剂量,两片TLD所测数值取均值。记录以上各种扫描时的容积CT剂量指数（CTDI_vol）和剂量长度乘积（DLP）,测量眼晶状体层面和甲状腺层面影像的对比度噪声比（CNR）。结果 120 kV+200 mAs扫描时,眼晶状体和甲状腺的器官剂量分别为19.8和26.0 mGy,使用120 kV+200 mAs+X-CARE可降低剂量至13.3和22.2 mGy;与CARE Dose 4D+120 kV相比,CARE Dose 4D+CARE kV可使CTDI_vol由13.1降至10.1 mGy,眼晶状体剂量和甲状腺剂量由20.8和23.7 mGy分别降至16.6和19.9 mGy,而使用CARE Dose 4D+CARE kV+X-CARE时,器官剂量又进一步分别降至6.3和11.0 mGy,但影像质量显著降低;与CARE Dose 4D+120 kV相比,使用CARE Dose 4D+120 kV+X-CARE,眼晶状体和甲状腺剂量分别由20.8和23.7 mGy降至9.6和15.1 mGy,同时CTDI_vol由13.1 mGy降至9.3 mGy。使用CARE Dose 4D+CARE kV+X-CARE时,CTDI_vol和器官剂量降至最低,但头颅和颈部CNR也降至最低。结论 颅脑扫描时CARE Dose 4D+120 kV+X-CARE模式、颈部扫描时CARE Dose 4D+CARE kV模式在保持影像质量较好的同时可有效降低辐射剂量。当对影像质量要求不高时可选用CARE Dose 4D+CARE kV+X-CARE模式,从而显著降低辐射剂量。     

Impact of organ-specific dose reduction on the image quality of head and neck CT angiography

Objectives

Organ-specific dose reduction (OSDR) algorithms can reduce radiation on radiosensitive organs up to 59 %. This study evaluates the influence of a new OSDR algorithm on image quality of head and neck computed tomographic angiography (CTA) in clinical routine.

Methods

Sixty-two consecutive patients (68?±?13 years) were randomised into two groups and imaged using 128-row multidetector CT. Group A (n?=?31) underwent conventional CTA and group B (n?=?31) CTA with a novel OSDR algorithm. Subjective and objective image quality were statistically compared. Subjective image quality was rated on a five-point scale. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated with region-of-interest measurements.

Results

The SNR of the common carotid artery and middle cerebral artery was 53.6?±?22.7 and 43.3?±?15.3 (group A) versus 54.1?±?20.5 and 46.2?±?14.6 (group B). The CNR was 40.0?±?19.3 and 29.7?±?12.0 (group A) compared with 40.7?±?16.8 and 32.9?±?10.9 (group B), respectively. Subjective image quality was excellent in both groups (mean score 4.4?±?0.7 versus 4.4?±?0.6). Differences between the two groups were not significant.

Conclusions

The novel OSDR algorithm does not compromise image quality of head and neck CTA. Its application can be recommended for CTA in clinical routine to protect the thyroid gland and ocular lenses from unnecessary high radiation.

Key Points

? Organ-specific dose reduction (OSDR) can significantly reduce radiation exposure during CT ? OSDR does not compromise image quality of head and neck CTA ? OSDR can significantly lower the risk of radiation damage to sensitive organs ? OSDR can easily be applied in routine clinical practice     

不同肠道准备对腹部增强CT图像质量的影响

目前,在临床CT检查前的肠道准备方法有很多,为了探讨不同肠道准备对腹部增强CT图像质量的影响,本文收集2010年9月～2012年2月分别采用3％甘露醇和1％泛影葡胺同时、分次口服对56例腹部增强CT检查患者进行检查前肠道准备,并与采用1％肥皂水清洁灌肠后分次服用1％泛影葡胺的肠道准备方法的对照组患者进行肠道充盈效果、CT图像质量、肠道准备所需时间、不良反应对比研究,取得了良好的临床效果,现将结果报道如下.     

鼻窦低剂量CT扫描对图像质量影响的研究

目的探讨鼻窦CT扫描时单纯降低mA值,晶体接受的射线剂量及其对图像质量的影响。方法将50例行鼻窦冠状面CT扫描者根据有无炎症分为正常组(32例)与炎症组(18例)。每组患者根据扫描的mA值设置分为200mA和50mA组。正常组有8例,炎症组有7例同时行高分辨重建。用镁铜磷氟化锂[LiF(Mg·Cu·P)]热释光探测器测量晶体受到的照射剂量。评价不同条件、不同算法(软组织算法和高分辨算法)时的图像质量。评价指标为中鼻甲、钩突、上颌窦开口、筛漏斗、额隐窝、筛板。评价标准为未显示,0分;显示、但不清楚,1分;清楚显示,2分。左右单独计分。结果当mA值由200减至50时,晶体所接受的射线剂量由7339mGy降至1108mGy。两组差异有统计学意义(P<001)。而图像质量无明显下降(P>005)。对于正常组,高分辨重建有助于细小解剖结构的显示,对于炎症组高分辨重建并不能增加细节的显示程度。结论在单纯降低mA值的条件下,受检者所接受的射线剂量明显减少,虽然图像噪声有所增加,但图像仍然保持较好的诊断质量。     

SPECT图像重建方法对Hoffmann模型图像质量的影响

目的探讨SPECT显像不同断层重建方法对Hoffmann模型图像质量的影响。方法采用放射性线源及Hoffmann模型,进行SPECT配平行孔低能高分辨准直器断层采集。对线源图像和Hoffmann模型图像均用滤波反投影（FBP）法和有序子集最大期望值迭代（OSEM）法进行断层重建。对线源重建图像计算2种重建算法的半高宽（FWHM）值,视觉评价2种方法重建的Hoffmann模型图像,并比较2种重建方法的重建时间和模型特定感兴趣区（ROI）。采用SPSS15．0软件,2种重建方法的脑叶及基底节ROI与小脑ROI计数比值行两独立样本t检验。结果平行孔低能高分辨准直器采集的线源断层图像经FBP法和OSEM法重建,FWHM值分别为18．77mm,12．62mm。OSEM法重建所得Hoffmann模型总的图像质量、基底节区的显示以及核团分辨程度均优于FBP法。FBP法和OSEM法重建时间分别为80s和100s,均在临床允许范围之内。OSEM迭代与FBP法脑叶及基底节ROI与小脑ROI比值差异无统计学意义（t=-0．332,P=0．750）。结论在现有软硬件技术条件下,平行孔低能高分辨准直器配合OSEM法优于FBP法,可获得空间分辨率和图像质量较好的Hoffmann模型重建图像。     

iDose迭代重建算法对上腹部CT图像质量的影响

目的 比较不同水平的iDose迭代重建算法对上腹部CT增强扫描门静脉期图像质量的影响,获取本组图像质量相对较好的iDose迭代水平.方法 采用256层螺旋CT扫描仪对60例患者行4期上腹部CT增强扫描,对门静脉期的图像采用滤波反投影(FBP)、iDose1、iDose3、iDose5共4种方式的重建,比较不同重建方式下图像客观质量,包括噪声、信噪比(SNR)、对比噪声比(CNR),以及主观质量(噪声、锐利度、对比度、伪影、细小结构的清晰度)的差异.结果 4组图像的客观质量差异均有统计学意义(P＜0.05),iDose各组图像的客观噪声均低于FBP组,而SNR、CNR均高于FBP组(P＜0.05),iDose5组的SNR、CNR最高.与FBP组相比,iDose各组图像的主观噪声更低,锐利度、对比度及细小结构清晰度更好(P＜0.05),4组图像的伪影差异无统计学意义(P＞0.05).iDose3水平重建后图像的总体指标最好.结论 常规上腹部CT增强扫描时,应用iDose迭代算法重建后图像的噪声降低,总体质量提高.     

Multidetector CT of bronchiectasis: effect of radiation dose on image quality

OBJECTIVE: The purpose of our prospective study was to assess the image quality with respect to the radiation dose incurred by multidetector CT (MDCT) in patients with suspected bronchiectasis. SUBJECTS AND METHODS. Image clusters, composed of nine images, using MDCT (120 kVp, a 2.5-mm collimation, a pitch of 6, and 2.5-mm reconstruction intervals) were obtained at each of two levels-the azygous arch and the right inferior pulmonary vein-at 170, 100, 70, 40, 20, and 10 mA. Independently, two chest radiologists assessed and compared the quality of the images obtained at the six milliamperage exposures. Image quality was graded using a 5-point scale with lung and mediastinal window settings. Radiation doses were measured at each of the six milliamperage settings while scanning the whole lung of a thoracic phantom using MDCT. RESULTS: The mean image quality scores at exposures of 170, 100, 70, 40, 20, 10 mA were as follows: 3.9, 3.7, 3.8, 3.2, 2.5, 1.6 at lung window settings and 4.1, 4.3, 4.0, 3.4, 2.3, 1.3 at mediastinal window settings, respectively. Images obtained at 70 mA were rated significantly better than those obtained at 40 mA or less (p < 0.01). The mean radiation dose at 170, 100, 70, 40, 20, 10 mA was 23.72, 14.39, 10.54, 5.41, 2.74, and 1.50 mGy, respectively. CONCLUSION: With a tube current setting as low as 70 mA, MDCT provides images of acceptable quality and volumetric data sets for the evaluation of bronchiectasis. The trade-off of using MDCT rather than conventional high-resolution CT is that the radiation dose is five times higher with MDCT (10.54 mGy) than with conventional high-resolution CT (2.17 mGy with parameters of 120 kVp, 170 mA, 1-mm collimation, and 10-mm intervals).