PET图像勾画肿瘤靶区边界的水模研究

目的 通过水模研究,探讨影响18F-脱氧葡萄糖（FDG）PET图像靶区勾画阈值（TH%）的因素,建立计算阈值的公式,为不同生物学特征的肿瘤选取不同阈值.方法 对特制的拥有5个不同大小靶区、7种不同靶区本底放射性比值的水模进行PET/CT图像采集,由图像得到每个靶区的最大标准摄取值（SUVmax）、靶区边界处的SUV（SUVborder）、本底中1 cm×1 cm大小感兴趣区的平均SUV（SUVbg）以及靶区内径（D）等,使用SPSS 13.0的曲线估计和线性回归分析方法,得到计算阈值的公式,并以此对29个经病理检查确诊的肺癌原发灶或转移淋巴结进行肿瘤靶区勾画,求出体积,比较PET和CT图像勾画的体积间的差别.结果 通过分析水模数据,得出阈值与靶区的大小呈负相关,与靶区的SUVmax呈负相关,与SUVbg呈正相关,阈值的计算公式为TH%=33.1%＋46.8%×SUVbg/SUVmax＋13.9%/D,r=0.994.通过对29个病灶进行比较,发现PET和CT勾画的平均大体肿瘤体积（GTV）分别是（7.36±1.62）ml和（8.31±2.05）ml,两者间差异无统计学意义（t=-1.26,P＞0.05）.结论 靶区的大小、SUVmax及SUVbg均会影响靶区勾画阈值;通过公式TH%=33.1%＋46.8%×SUVbg/SUVmax＋13.9%/D可对不同肿瘤计算合适的阈值.按此公式PET和CT勾画的靶区无明显差异.     

磁共振影像对勾画大体肿瘤体积的影响

在确定中枢神经系统和头颈部不规则肿瘤时,磁共振影像MRI比CT影像有优势,特别是位于后窝或颅底的肿瘤、增强不明显的肿瘤、星形细胞瘤,若放射治疗医生直接在CT影像上勾画大体肿瘤体积（GTV）,则必须参考磁共振影像胶片;若把MRI影像套准在CT影像上,放射治疗医生不仅能直接在MRI上勾画GTV,而且能有效减小不同医生在勾画GTV时产生的偏差.     

18F-FDG PET/CT显像在宫颈癌术后复发和转移中的应用价值

目的 探讨18F-FDG PET/CT显像在宫颈癌术后复发和转移中的应用价值.方法 搜集临床可疑宫颈癌术后复发和转移患者65例,年龄23～77岁,平均48.7岁.所有宫颈癌患者均经手术病理确诊并行根治性治疗,其中鳞癌47例,腺癌12例,腺鳞癌4例,透明细胞癌1例,小细胞癌1例.患者均行18F-FDG PET/CT全身显像检查,采用目测法和半定量法判断结果,并与组织病理或临床随访结果比较其诊断的准确性,以及评价其诊断的真实性和可靠性.结果 65例患者经组织病理或临床随访证实50例复发和转移.18F-FDG PET/CT显像诊断肿瘤局部复发18例,肿瘤转移33例,复发和转移病灶的SUVmax 2.91 ～ 16.70,平均SUVmax 9.81,18F-FDG PET/CT显像诊断宫颈癌术后复发和转移的灵敏度为98.00％,特异性为86.67％,准确性为95.38％,阳性预测值为96.08％,阴性预测值为92.86％;18F-FDG PET/CT显像诊断结果与组织病理或临床随访结果比较差异无统计学意义(经x2检验,P＞0.05);二者结果的吻合度有统计学意义且吻合度较强(系数k=0.867,P=0.000).结论 18F-FDG PET/CT显像能够准确、直观地显示宫颈癌术后复发和转移,且真实性和可靠性好;同时18F-FDG PET/CT全身显像检查是肿瘤远处转移探测最有效的方法,可较全面评估患者病情,对协助临床确定个体化治疗方案具有重要价值.     

PET/CT对头颈部肿瘤放射治疗计划的作用

目的 探讨PET/CT对头颈部肿瘤放射治疗计划的作用.方法 16例头颈部肿瘤患者行PET/CT和定位CT检查,根据检查结果对16例患者进行TNM分期,比较其分期结果.将定位CT图像传入三维治疗计划系统(TPS),在定位CT图像上勾画大体肿瘤体积(GTV),即CT-GTV;参考PET/CT融合图像在定位CT图像上勾画PET/CT-GTV,比较PET/CT-GTV和CT-GTV.采用Stata 7.0软件分析数据,t检验用于比较PET/CT-GTV和CT-GTV.结果 PET/CT使7例患者TNM分期发生改变.PET/CT-GTV和CT-GTV中位值分别为84.3(46～364)cm3和116.2(58～472)cm3,差异有统计学意义(t=-4.3186, P=0.0005).结论 PET/CT能提高头颈部肿瘤分期和肿瘤靶区定位的准确性.     

18F-FDG PET/CT对原发不明颈部淋巴结转移癌患者原发灶检出的价值

目的 探讨18F-FDG PET/CT在原发不明颈部淋巴结转移癌患者原发灶检出中的临床应用价值.方法 回顾性分析2007年至2012年间因颈部淋巴结细针穿刺活组织检查提示转移但原发不明而行18F-FDG PET/CT检查的患者78例,其中男48例,女30例,平均年龄(56.4±14.7)岁.在PET/CT图像上勾画ROI并计算SUVmax.将淋巴结分为Ⅰ～Ⅵ区、咽后区及锁骨上区,取淋巴结短径为其大小.患者均经病理、随访确诊.观察肿瘤原发灶部位、病理类型及转移淋巴结分布、大小及SUVmax.采用单因素方差分析及直线相关分析分析数据.结果 78例患者中,恶性75例,良性3例(手术切除后病理检查).56例患者由PET/CT检出原发灶,检出率为71.8％(56/78).其中头颈部肿瘤占57.1％(32/56),对应转移淋巴结多分布于Ⅱ、Ⅲ、Ⅳ区(90.6％,29/32);体部肿瘤占42.9％(24/56),对应转移淋巴结多分布于锁骨上区(95.8％,23/24).不同原发部位及不同病理类型的颈部转移淋巴结大小和SUVmax差异均无统计学意义(F=0.037～ 2.413,均P＞O.05).结论 18F-FDGPET/CT有利于判断原发不明肿瘤的大致部位,并了解全身病灶分布.     

基于放疗中重复4D-CT扫描胸段食管癌肿瘤靶区体积变化的研究

靶区确定及适应性修正是食管癌精确放疗的核心环节。放疗过程中靶区体积及位移变化是靶区修改和计划修正的依据,相对于三维CT(3D-CT),四维CT(4D-CT)扫描既可以获得不包含运动信息的肿瘤靶区,如基于单时相图像勾画所得大体肿瘤体积(GTV),又可以获得包含放疗分次内全部运动信息的肿瘤靶区,如基于全部时相GTV融合所得内大体肿瘤体积(IGTV)或基于最大密度投影(maximum intensity projection, MIP)图像勾画所得相应IGTV。本研究基于重复4D-CT扫描探讨放疗疗程中靶区体积变化。     

PET/CT联合高分辨超声对甲状腺偶发病灶良恶性鉴别诊断的价值

目的 探讨PET/CT联合高分辨超声(US)对甲状腺偶发病灶良、恶性的鉴别诊断价值.方法 对73个PET/CT检出的甲状腺偶发病灶病理确诊前PET/CT和US诊断意见按3分法(0分,良性可能;1分,无明确定性;2分,恶性可疑)分类,并测定病灶长径和SUVmax.以病理诊断为“金标准”,评价SUVmax、PET/CT、US、PET/CT联合US( PET/CT+US)对恶性病灶的检出效能.统计学检验包括t检验、Z检验、x2检验和Kappa一致性检验.结果 73个甲状腺偶发病灶病理确诊恶性病灶占59％(43/73),良性病灶占41％(30/73).恶性病灶SUVmax (7.0±8.1)高于良性病灶(4.1±3.8;t=2.062,P=0.043),长径小于良性病灶[(2.0±1.1) cm比(2.7±1.4) cm;t=2.628,P=0.011].SUVmax、PET/CT、US及PET/CT+ US诊断恶性病灶的ROC AUC(95％CI)分别为0.580(0.448-0.713)、0.763 (0.647～0.878)、0.905(0.826～0.983)和0.909(0.840～0.979),PET/CT AUC明显大于SUVmax(Z=2.033,P=0.042),US、PET/CT+US也明显大于PET/CT(Z值分别为1.992和2.112,P均＜0.05)和SUVmax(Z值分别为4.120和4.276,P均＜0.001).最佳阈值下,SUVmax、PET/CT、US、PET/CT+US诊断的灵敏度、特异性、准确性、阳性预测值、阴性预测值分别为42％(18/43)、83％(25/30)、59％(43/73)、78％(18/23)、50％(25/50),79％(34/43)、80％(24/30)、79％(58/73)、85％(34/40)、73％(24/33),84％(36/43)、90％(27/30)、86％(63/73)、92％(36/39)、79％(27/34)和98％(42/43)、67％(20/30)、85％(62/73)、81％(42/52)、95％(20/21).与病理诊断比较,SUV.诊断的一致性较差(Kappa=0.229,P=0.023),PET/CT的一致性中等(Kappa=0.582,P＜0.001),US和PET/CT+US的一致性好(Kappa值分别为0.668和0.674,P均＜0.001).PET/CT+US与PET/CT比较,灵敏度从79％(34/43)提高到98％(42/43),差异有统计学意义(x2=6.125,P=0.008),而特异性差异无统计学意义(从80％降低到67％;x2=2.250,P＞0.05).结论 联合高分辨US能明显提高18F-FDG PET/CT对甲状腺偶发病灶良、恶性的鉴别诊断效能.     

18F-FDGPET/CT勾画鼻咽癌原发肿瘤体积最适阈值的研究

目的 寻找¹⁸F-FDG PET/CT勾画鼻咽癌大体肿瘤体积（GTV）的最适阈值。 方法 16例初诊鼻咽癌患者在治疗前接受¹⁸F-FDG PET/CT及MRI检查,将MRI/CT融合图像上勾画的肿瘤GTV定义为GTV_f,¹⁸F-FDG PET/CT勾画肿瘤范围为BTV。不同阈值条件下的BTV通过调整最大标准摄取值（SUV_max）的比例得到。将不同阈值条件下的BTV和GTV_f进行比较,当二者在体积及形态学上达到最佳匹配时对应的阈值水平为最适阈值（sTL）。sTL×SUV_max得到相应的最适标准摄取值（sSUV）。 结果 16例患者最适阈值sTL（%）为20.93±6.51, 相应的最适标准摄取值sSUV为2.27±0.48。 sTL与SUV_max呈负相关（R²=0.85,F=78.57,P<0.05）;sSUV与SUV_max呈正相关（R²=0.75,F=41.88,P<0.05）;sTL与GTV_f无相关性。 结论 利用SUV_max阈值法勾画鼻咽癌GTV是可行的,最适阈值不是一个固定数值,与SUV_max相关,与肿瘤体积没有明显相关性。     

用18F-FDG PET/CT勾画肺肿瘤靶区最佳阈值的模型研究

目的 通过模型实验初步建立使18F-脱氧葡萄糖(FDG)PET图像上显示的肿瘤体积肿瘤实际体积一致的最佳阈值条件.方法 采用美国DATA SPECTUM公司NEMA IEC-BodyPhantom setTM>体模,以不同大小的球体(体积分别为0.52,1.15,2.60,5.50,11.40,26.50 ml)模拟临床常见肺肿瘤的大小和靶/本底(T/B)比值.选择合适的窗位和窗宽,使CT图像上显示的球体体积与球体实测体积一致,并以此作为球体的实际体积,调节PET图像的阈值,使PET图像上勾画的球体轮廓与CT图像上所勾画的最接近.设绝对阈值(Ithreshold)=本底平均像素值(Iback)+相对阈值[x%Imax-back(slice)>,即每个层面的最大像素值与本底平均像素值的差值的百分比].比较应用筛选出的最佳绝对阈值与应用最广泛的靶体内最大像素值[42%Imax(total)>]为阈值勾画的球体体积大小及对实际体积覆盖率的差异.采用SPSS 13.0软件进行统计学处理,行Wilcoxon法检验.结果 对体积≥5.50 ml的不同T/B比值的球体,中央1/2层面的最佳相对阈值与最大层面的最佳相对阈值相差(1.6±2.0)%,而两端1/2层面的最佳相对阈值与最大层面的最佳相对阈值相差(19.3±10.1)%,二者差异有统计学意义(Z=-7.26,P<0.01).最大层面的最佳相对阈值在20%～25%之间的改变引起勾画体积与实际体积的差异≤5%.以Ithreshold=Iback+20%Imax-back作为各层面的最佳绝对阈值,所勾画的球体体积较实际体积扩大(12.6±6.6)%,而42%Imax(total)勾画的体积较实际体积缩小(-17.2±15.2)%(Z=2.67,P<0.01),前者对实际体积的覆盖率优于后者(97.1%与79.4%,Z=-2.67,P<0.01).结论 Iback+20%Imax-back(slice)可能是不依赖于CT提供的肿瘤体积信息层面化的最佳阈值条件,其准确性优于42%Imax(total)阈值法.     

18F-FDG PET/CT显像在治疗后宫颈癌评估中的价值

目的 探讨18F-FDG PET/CT对临床怀疑宫颈癌局部复发和(或)远处转移患者的诊断价值.方法 回顾性分析95例宫颈癌治疗后患者的18F-FDG PET/CT检查资料,采用视觉分析和半定量方法(SUVmax)分析病灶特点,最终诊断以活组织病理检查、诊断性治疗及影像学随访结果为准,采用Kappa一致性检验进行分析.结果 共有54例患者18 F-FDG PET/CT检查发现局部复发和(或)远处转移病灶,其中局部复发24例,远处转移30例;18F-FDG PET/CT诊断肿瘤复发与转移的灵敏度、特异性和准确性分别为98.1％(52/53)、95.2％ (40/42)和96.8％ (92/95),阳性预测值与阴性预测值分别为96.3％ (52/54)和97.6％(40/41).18F-FDG PET/CT检查结果与病理及临床随访结果一致性良好(Kappa=0.936,P＜0.05).结论 18F-FDG PET/CT对临床可疑宫颈癌复发的诊断具有较高的灵敏度和特异性,有助于局部复发和(或)远处转移病灶的检测,对临床进一步的诊疗具有指导作用.     

Computerized estimation of the lung volume removed during lung volume reduction surgery

RATIONALE AND OBJECTIVES: This study was designed to develop an automated method for estimating lung volume removed during lung volume reduction surgery (LVRS) using computed tomography (CT). MATERIALS AND METHODS: The CT examinations of six patients who underwent bilateral LVRS were analyzed in this study. The resected lung tissue (right and left) was weighed during pathologic examination. An automated computer scheme was developed to estimate the lung volume removed using the CT voxel values and lung specimen weight. The computed fraction of lung volume removed was evaluated across a range of simulated surgical planes (ie, other than parallel to the CT image plane) and CT reconstruction kernels, and it was compared with the surgeons' postsurgical estimates. RESULTS: The computed fraction of the lung volume removed during LVRS was linearly correlated with the resected lung tissue weight (Pearson correlation = 0.697, P = .012). The computed fraction of lung volume removed ranged from 12.9% to 51.7% of the total lung volume. The surgeons' postsurgical estimates of lung volume removed ranged from 30% to 33%. The percent difference between the surgeons' estimates and the computed lung volume removed as a percentage of the surgeons' estimates ranged from -72.3% to 57.0% with mean absolute difference of 29.7% (+/-20.7). CONCLUSION: The preliminary findings of this study suggest that the proposed quantitative model should provide an objective measure of lung volume removed during LVRS that may be used to investigate the relationship between lung volume removed and outcome.     

Reduction in sella turcica volume

Summary Ten patients with acromegaly were treated with the long-acting somatostatin analogue, Sandostatin (SMS 201-995, octreotide) for more than one year. Computerized tomography was performed before and on 4 different occasions during the treatment. Sella turcica volumes were calculated in nine patients and showed a gradual decrease in all, averaging 32%±14.6%,P<0.001 at the end of the study, which is probably indicative of a simultaneous reduction in adenoma size.     

Measurement and determinants of infrarenal aortic thrombus volume

Intra-luminal thrombus has been suggested to play a role in the progression of abdominal aortic aneurysm (AAA). The aims of this study were twofold. Firstly, to assess the reproducibility of a computer tomography (CT)-based technique for measurement of aortic thrombus volume. Secondly, to examine the determinants of infrarenal aortic thrombus volume in a cohort of patients with aortic dilatation. A consecutive series of 75 patients assessed by CT angiography with maximum aortic diameter >/=25 mm were recruited. Intra-luminal thrombus volume was measured by a semi-automated workstation protocol based on a previously defined technique to quantitate aortic calcification. Intra- and inter-observer reproducibility were assessed using correlation coefficients, coefficient of variation and Bland-Altman plots. Infrarenal aortic thrombus volume percentage was related to clinical, anatomical and blood characteristics of the patients using univariate and multivariate tests. Infrarenal aortic thrombus volume was related to the severity of aortic dilatation assessed by total aortic volume (r = 0.87, P < 0.0001) or maximum aortic diameter (r = 0.74, P < 0.0001). We therefore examined the clinical determinates of aortic thrombus expressed as a percentage of total aortic volume. Aortic thrombus percentage was negatively correlated with serum high density lipoprotein (HDL, r = -0.31). By ordinal multiple logistic regression analysis serum HDL below median (相似文献   

Value of ellipsoid volume masking in myocardial tomography

The circumferential profile technique, used to obtain a bull's eye image from short axis slices in myocardial perfusion tomography, requires isolation of the reconstructed volume from other neighbouring structures that may take up the radiopharmaceutical used. If this is not possible, some regional artefacts can be introduced in the polar map that do not represent the actual myocardial perfusion at the corresponding level. In this case report we describe a method for volume masking that permits the myocardium inside in ellipsoidal volume to be enclosed. This technique is compared with the spherical method used in a Sophy 20P system in a case with impaired perfusion of an inferolateral segment and an extracardiac hot structure located in the same area. The results obtained show the usefulness of our method in such cases.     

Stereological estimation of total intracranial volume on CT images

This study aims to investigate the possibility of generating stereological estimations of total intracranial volume (TIV) on CT scans. The study group included 16 consecutive patients referred for a cranial CT examination. The TIV was estimated using the stereological point counting technique. Volume measurements were optimized by systematically sampling CT sections and by defining an optimum spacing between test points of the grid. The intraobserver and interobserver variability of the optimized volumetric technique was determined. Stereological TIV estimations were compared with the respective planimetric measurements. The application of a test grid with a point spacing of 2.4 cm on 6–8 systematically sampled CT sections provided TIV estimations with a coefficient of error of less than 5%. The intraobserver and interobserver coefficient of variation values were found to be 2.4 and 4.0%, respectively. The 95% limits of agreement between stereological and planimetric TIV measurements were equal to –91.4 and 103.4 cm³. The mean time (±SD) needed to obtain stereological TIV estimations was 2.9±0.6 min. The application of the optimized stereological technique on CT scans enables the efficient estimation of TIV.     

Musculoskeletal applications of flat-panel volume CT

Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volumetric coverage; dynamic imaging; omni-scanning. The overall effective dose of fpVCT is comparable to that of MDCT scanning. Although current fpVCT technology has higher spatial resolution, its contrast resolution is slightly lower than that of MDCT (5-10HU vs. 1-3HU respectively). We discuss the efficacy and potential utility of fpVCT in various applications related to musculoskeletal radiology and review some novel applications for pediatric bones, soft tissues, tumor perfusion, and imaging of tissue-engineered bone growth. We further discuss high-resolution CT and omni-scanning (combines fluoroscopic and tomographic imaging).     

Cardiac computed tomography-derived coronary artery volume to myocardial mass

In the absence of disease impacting the coronary arteries or myocardium, there exists a linear relationship between vessel volume and myocardial mass to ensure balanced distribution of blood supply. This balance may be disturbed in diseases of either the coronary artery tree, the myocardium, or both. However, in contemporary evaluation the coronary artery anatomy and myocardium are assessed separately. Recently the coronary lumen volume to myocardial mass ratio (V/M), measured noninvasively using coronary computed tomography angiography (CTCA), has emerged as an integrated measure of myocardial blood supply and demand in vivo. This has the potential to yield new insights into diseases where this balance is altered, thus impacting clinical diagnoses and management.In this review, we outline the scientific methodology underpinning CTCA-derived measurement of V/M. We describe recent studies describing alterations in V/M across a range of cardiovascular conditions, including coronary artery disease, cardiomyopathies and coronary microvascular dysfunction. Lastly, we highlight areas of unmet research need and future directions, where V/M may further enhance our understanding of the pathophysiology of cardiovascular disease.     

Three-dimensional volume rendering of tibiofibular joint space and quantitative analysis of change in volume due to tibiofibular syndesmosis diastases

OBJECTIVE: The diagnosis of ankle syndesmosis injuries is made by various imaging techniques. The present study was undertaken to examine whether the three-dimensional reconstruction of axial CT images and calculation of the volume of tibiofibular joint space enhances the sensitivity of diastases diagnoses or not. DESIGN: Six adult cadaveric ankle specimens were used for spiral CT-scan assessment of tibiofibular syndesmosis. After the specimens were dissected, external fixation was performed and diastases of 1, 2, and 3 mm was simulated by a precalibrated device. Helical CT scans were obtained with 1.0-mm slice thickness. The data was transferred to the computer software AcquariusNET. Then the contours of the tibiofibular syndesmosis joint space were outlined on each axial CT slice and the collection of these slices were stacked using the computer software AutoCAD 2005, according to the spatial arrangement and geometrical coordinates between each slice, to produce a three-dimensional reconstruction of the joint space. The area of each slice and the volume of the entire tibiofibular joint space were calculated. The tibiofibular joint space at the 10th-mm slice level was also measured on axial CT scan images at normal, 1, 2 and 3-mm joint space diastases. RESULTS: The three-dimensional volume-rendering of the tibiofibular syndesmosis joint space from the spiral CT data demonstrated the shape of the joint space and has been found to be a sensitive method for calculating joint space volume. We found that, from normal to 1 mm, a 1-mm diastasis increases approximately 43% of the joint space volume, while from 1 to 3 mm, there is about a 20% increase for each 1-mm increase. CONCLUSIONS: Volume calculation using this method can be performed in cases of syndesmotic instability after ankle injuries and for preoperative and postoperative evaluation of the integrity of the tibiofibular syndesmosis.     

320排动态容积CT在冠心病筛查中的初步应用

目的探讨320排动态容积CT冠状动脉造影在冠状动脉粥样硬化性心脏病(冠心病)筛查中的应用。方法分析90例临床拟诊为冠心病患者的320排CT前瞻性心电门控全心容积扫描检查结果。对显示的冠状动脉主干及其主要分支进行分级评价,并对辐射剂量进行统计分析。结果本组90例,发现狭窄性病变70例,其中三支狭窄性病变10例,两支狭窄性病变25例,单支狭窄性病变35例;其中狭窄度≥50%35支(30.43%),<50%80支(69.57%)。90例冠状动脉成像质量1级80例(88.89%),2级9例(10%),3级1例(1.11%)。结论 320排CT冠状动脉成像速度快,图像质量高,辐射剂量低,是冠心病筛查的首选检查。