不同浓度口服泛影葡胺对PET/CT显像结果影响的模型研究

目的 探讨不同浓度口服泛影葡胺对PET/CT图像质量和标准摄取值(SUV)的影响.方法 使用乳胶指套自制多个密封的圆柱形容器,其内分别注入不同浓度的口服泛影葡胺溶液.将其置入一圆桶模型中,在模型内注满8.13 kBq/ml 18F-脱氧葡萄糖(FDG)溶液后进行PET/CT显像,同时采用CT及137Cs两种衰减校正方法,分别重建CT衰减校正(CTAC)图像、137Cs衰减校正(CsAC)图像及无衰减校正(NOAC)图像.选择所有不同浓度的泛影葡胺充盈区勾划感兴趣区(ROI),比较各ROI CTAC和CsAC的平均SUV差异,同时比较CTAC、CsAC及NOAC的图像差异.结果 在CTAC图像中,不同密度泛影葡胺充盈区的平均SUV随着CT值的增加而增加(r=0.990, P＜0.001),在CsAC图像中,其平均SUV随着CT值的增加无明显变化(r=0.015, P=0.958).在所有浓度≤4%(或CT值≤293 HU)的泛影葡胺充盈区,CTAC与CsAC之间平均SUV的差异无统计学意义(P均＞0.05).在所有浓度≥5%(或CT值≥411 HU)的泛影葡胺充盈区,CTAC的平均SUV明显高于CsAC(P均＜0.05).在CsAC及NOAC图像中,不同浓度泛影葡胺充盈区图像之间无明显差异,均表现为圆形"冷区".在CTAC图像中,当泛影葡胺浓度≥12%(或CT值≥961 HU)时,各充盈区图像出现不同程度的FDG高摄取伪影.结论 低浓度(CT值≤293 HU)口服泛影葡胺对PET/CT显像CTAC图像质量和标准摄取值无明显影响;各密度梯度泛影葡胺对CsAC图像质量和标准摄取值无明显影响;高浓度(CT值≥411 HU)口服泛影葡胺可使CTAC的SUV不同程度高估,以及出现不同程度的FDG高摄取伪影.     

18F-FDG标准化摄取值在不同衰减校正方式中的比较研究

目的比较应用X线CT和Cs透射数据对PET发射数据进行衰减校正时,标准化摄取值(SUV)的差异。方法以Philips圆柱体空心SUV校正模型和20例患者为研究对象,在PET/CT全身三维显像模式中,分别用X线CT和137Cs透射数据做PET发射数据的衰减校正(CTAC和CsAC)。分别在CTAC及CsAC均匀水模的中心15层横断面图像的相同位置,以及所有患者相同部位的肌肉、脂肪、肠道、肝脏、肺、心肌、脑、骨等不同密度的正常组织中,划取相同大小的感兴趣区(ROI),通过计算机自动测量各ROI的平均SUV,并在CT横断面图像的相应位置测量人体组织的平均CT值。然后将所有被测人体组织分为软组织和骨组织两组,分别比较分析各组中CTAC和CsAC平均SUV的差异,及这种差异与CT值的相关性。全部采用临床全身显像的三维重建算法来重建图像。结果模型研究结果:在不同活性时,CsAC方式均能得到稳定可靠的SUV。而CTAC方式得到的SUV随着放射性活性水平降低,有逐渐升高的趋势。在单位活度6.253MBq/kg至4.292MBq/kg之间,即制造商推荐的标准给药活性(5.18MBq/kg体重)附近,CTAC和CsAC方式测得的SUV相同;患者研究结果:除脑组织以外的所有软组织中,CTAC的平均SUV较CsAC者低17%(t=-5.328,P=0.000),相应部位所测得的CT值为-850～68Hu[平均(-87±295)Hu],平均SUV的差异与相应的CT值呈负相关(r=-0.237,P=0.000);在骨组织中,CTAC的平均SUV较CsAC者高16%(t=7.960,P=0.000),相应部位所测得的CT值为105～550Hu[平均(334±151)Hu],平均SUV的差异与相应的CT值呈正相关(r=0.539,P=0.000)。结论①不同活性水平时,CsAC方式的SUV稳定、可靠,而CTAC方式的SUV稳定性和可靠性差;②模型模拟标准临床显像程序来测试PET/CT定量指标的稳定性具有明确的实用价值;③呼吸运动和组织衰减系数由低能向高能转换过程所带来的误差等,也是影响CTAC方式SUV稳定性的主要因素。     

PET/CT检查过程中口服增强造影剂泛影葡胺对体内FDG代谢的影响

目的:研究口服增强造影剂对体内FDG代谢的影响。方法:63例行PET／CT检查且显像图像未见异常FDG摄取的病人随机分为3组。对照组20例,显像前未口服任何造影剂;增强组26例,显像前40 min服1％的泛影葡胺溶液1 000ml;饮水组(阴性对照组)17例,显像前40 min服清水1 000 ml。静脉注射18F-FDG 0．15 mCi／Kg后45 min进行全身PET／CT显像。在PET横断面图像的左侧小脑皮质、主动脉弓、右肺、肝右叶、第5腰椎椎体和臀部肌肉位置勾画圆形感兴趣区(ROI),计算ROI内的标准摄取值 SUV,并将3组病人各部位SUV的数值进行比较。结果:增强组病人肺、主动脉弓、肝脏及肌肉的FDG摄取均显著低于对照组和阴性对照组(饮水组)(P<0．05);而对照组和饮水组间各部位FDG摄取无显著差异(P>0．05)。结论:PET／CT检查时口服造影剂泛影葡胺有可能影响体内FDG的代谢水平,从而可能影响肿瘤组织对FDG的摄取,在进行诊断和对SUV值分析时应加注意。     

PET/CT衰减系数转换方法对标准摄取值测量的影响研究

目的研究两种不同的衰减系数转换方法对正电子发射计算机断层显像/计算机体层扫描（PET/CT）标准摄取值（SUV）测量值的影响。方法 2009年11-12月,从经过PET/CT氟代脱氧葡萄糖（FDG）显像患者中选取20例,其口腔中均有金属假牙。以四段转换法和二段转换法重建全身衰减校正断层图像。分别选取3种高密度区域和7种低密度区域,测量其最大SUV和平均SUV,比较两种转换方法SUV测量值。结果平均SUV：二段转换法的3种高密度区域SUV降低,在7种低密度区域中,1种区域增高,1种区域降低（P值均〈0.05）。最大SUV：二段转换法的2种高密度区域的SUV降低,在7种低密度区域中,1种区域增高,2种靠近高密度组织的区域降低（P值均〈0.05）。结论二段转换法能降低高密度区域的SUV,可用于减小体内金属植入物和CT对比剂造成的过度校正。     

饮水充盈胃CT扫描275例效果分析

目的 探讨饮水充盈胃CT扫描在胃病变诊断中的应用价值.方法 回顾性分析比较275例饮水充盈胃与420例口服泛影葡胺稀释液充盈胃的CT扫描资料.结果 饮水充盈胃CT扫描对胃壁厚度、黏膜侧及胃部病变的显示率高于口服泛影葡胺稀释液(P<0.01);两种方法 对腹腔淋巴结转移显示率均低,差异无显著性意义(P>0.05).结论 饮水充盈胃加静脉推注泛影葡胺(过敏者禁用),对胃的显示具有明显优势,并且可提高胃部病变特别是小病变的显示率.     

消化系统肿瘤FDGPET／CT显像标准摄取值与分子生物学的相关性

目的探讨消化系统肿瘤PET/CT显像FDG标准摄取值（SUV）与其分子生物学行为的相关性。方法回顾性分析资料完整的24例消化系统肿瘤患者PET/CT、手术和病理资料,分析患者PET/CT显像FDG摄取指数SUV值与癌肿浸润深度、转移状况之间的相关性以及与肿瘤增殖因子Ki-67、癌基因p53、癌基因C-erbB-2表达的相关性。结果 24例消化系统肿瘤患者SUV值最低为2.5,最高为12,平均值6.34±2.54,按SUV值高低将患者病变均分为低代谢和高代谢两组,低代谢组SUV均值4.39±1.31,高代谢组SUV均值8.48±1.38,两组间SUV值均数差异有统计学意义（t=2.418,P〈0.05）,两组间病变浸润深度差异无统计学意义（χ2=0,P〉0.05）,两组间病变邻近淋巴结转移发生率无统计学意义（χ2=0.686,P〉0.05）。24例患者病变Ki-67值最低为20%,最高为65%,平均值（41±11）%。SUV值与Ki-67值相关性无统计学意义（r=-0.22,P〉0.05）。低代谢组和高代谢组Ki-67值分别为（43±13）%和（38±9）%,组间差异无统计学意义（t=0.225,P〉0.05）。低代谢组和高代谢组p53阳性表达例数差异无统计学意义（χ2=0.711,P〉0.05）。低代谢组和高代谢组C-erbB-2阳性表达例数差异无统计学意义（χ2=0.686,P〉0.05）。结论消化系统肿瘤PET/CT显像FDG摄取指数SUV值变异较大,与癌肿浸润深度和邻近淋巴结有无转移之间没有相关性,与肿瘤增殖因子Ki-67、癌基因p53及C-erbB-2表达程度无显著相关性。     

18F-FDGPET/CT显像锁骨上区脂肪摄取2例

例1,女,22岁,发现左颈部肿物1个月,为明确病变性质而行全身18F-FDG PET/CT检查.PET/CT图像显示,左颈部可见一增大淋巴结,FDG摄取明显增高,SUV(标准摄取值)7.1.此外,PET图像上于双侧锁骨上区、胸背部、上纵隔、胸椎旁可见多发大小不等团块状、结节状FDG浓集影,双侧基本对称,边界不清(图1A),浓集程度不一,SUV 3.2～6.7,与CT图像融合后显示浓集影位于肌间隙脂肪组织内(图1B).     

胃肠道肿瘤患者行 PET-CT 检查过程中口服造影剂的护理

目的：探讨如何做好 PET-CT 检查过程中给予口服造影剂的护理配合。方法对200例胃肠道肿瘤患者行静脉注射18F-FDG 后,分次给予1％泛影葡胺溶液口服。结果197例患者口服泛影葡胺溶液后胃肠道充盈较好,图像清晰,无伪影,符合诊断要求。结论胃肠道肿瘤患者行 PET-CT 检查程中口服泛影葡胺时,给予积极有效的护理指导是患者口服对比剂取得满意效果的重要保证。     

口服并灌肠泛影葡胺用于全腹CT扫描的护理体会

目的探讨口服并灌肠泛影葡胺用于全腹CT扫描检查的护理效果。方法将93例全腹CT扫描检查患者随机分为对照组46例和观察组47例。观察组采用检查前1h口服1%-1.5%泛影葡胺1000-1200ml,CT扫描检查时再行1%-1.5%泛影葡胺400-500ml保留灌肠,即行扫描检查。对照组采用于检查前3h口服1%~1.5%泛影葡胺2000ml充盈肠道等待检查。结果观察组肠道造影剂充盈时间比对照组提前1.8-2.04h,两组比较有显著性差异（P〈0.05）。结论口服并灌肠泛影葡胺用于全腹CT扫描检查,减轻了患者的痛苦,提高了影像检查质量和正确诊断率。     

~(18)F-FDG PET显像鉴别诊断肺部肿块性质的价值

目的 探讨~(18)F-2脱氧葡萄糖(FDG)PET(正电子发射型计算机断层摄影)显像鉴别诊断肺部肿块性质的价值。方法 对18例肺癌患者和7例肺部良性病变患者进行了~(18)F-FDG PET代谢显像,用定性和半定量方法进行分析,并与病理结果进行比较。结果 18例原发性肺癌中,除1例癌灶表现为轻度摄取外,其余病例可见肺内局部单个或多个明显FDG浓集区(SUV=4.68±2.12)。7例良性病例中,1例干酪样坏死病灶明显摄取FDG(SUV=5.6),1例多发性结核球病灶轻度摄取FDG(SUV=1.2-1.7),其余5例均未见FDG浓集区(SUV=1.59±0.57),恶性病变组SUV明显高于良性病变,差异有显著性(t=4.12,P<0.01)。~(18)F-FDG PET显像鉴别肺部肿块性质的灵敏度和特异性分别为94.4％和71.4％。结论 ~(18)F-FDG PET显像鉴别诊断肺部恶性肿块性质的灵敏度高,物异性较低,其价值主要在于筛选作用,可避免不必要的手术治疗。     

Quantitative Effects of Contrast Enhanced CT Attenuation Correction on PET SUV Measurements

Purpose The presence of contrast materials on computed tomography (CT) images can cause problems in the attenuation correction of positron emission tomography (PET) images. These are because of errors converting the CT attenuation of contrast to 511-keV attenuation and by the change in tissue enhancement over the duration of the PET emission scan. Newer CT-based attenuation correction (CTAC) algorithms have been developed to reduce these errors. Methods To evaluate the effectiveness of the modified CTAC technique, we performed a retrospective analysis on 20 patients, comparing PET images using unenhanced and contrast-enhanced CT scans for attenuation correction. A phantom study was performed to simulate the effects of contrast on radiotracer concentration measurements. Results There was a maximum difference in calculated radiotracer concentrations of 5.9% within the retrospective data and 7% within the phantom data. Conclusion Using a CTAC algorithm that de-emphasizes high-density areas, contrast-enhanced CT can be used for attenuation mapping without significant errors in quantitation.     

Reproducibility of Semi-quantitative Parameters in FDG-PET Using Two Different PET Scanners: Influence of Attenuation Correction Method and Examination Interval

Purpose The aim of this study is to evaluate the reproducibility of semi-quantitative parameters obtained from two 2-deoxy-2-[F-18]fluoro-d-glucose-positron emission tomography (FDG–PET) studies using two different PET scanners. Methods Forty-five patients underwent FDG–PET examination with two different PET scanners on separate days. Two PET images with different attenuation correction method were generated in each patient, and three regions of interest (ROIs) were placed on the lung tumor and normal organs (mediastinum and liver) in each image. Mean and maximum standardized uptake values (SUVs), tumor-to-mediastinum and tumor-to-liver ratios (T/M and T/L), and the percentage difference in parameters between two PET images (% Diff.) were compared. Results All measured values except maximum SUV in the liver and tumor-related parameters (SUV in lung tumor, T/M, T/L) showed no significant difference between two PET images. Conclusion The mean measured values showed high reproducibility and demonstrate that follow-up study or measurement of tumor response to anticancer drugs can be undertaken by FDG–PET examination without specifying the particular type of PET scanner.     

Comparison of Standardized Uptake Values in Normal Structures Between PET/CT and PET/MRI in an Oncology Patient Population

Purpose

The purpose of this study was to compare and correlate standardized uptake values (SUV) derived from magnetic resonance attenuation correction (MRAC) with those derived from computed tomography attenuation correction (CTAC) in an oncology patient population.

Procedures

The HIPAA-compliant study was approved by the Internal Review Board and all subjects gave written informed consent prior to inclusion in the study. Forty patients (mean age 61?±?15.1; 20 male) referred for clinically indicated 2-deoxy-2-[¹⁸F]fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) scans also underwent a PET/magnetic resonance imaging (MRI) examination. MRAC was performed using an automatic three-segment model. Regions of interest were drawn over eight normal structures in order to obtain SUVmax and SUVmean values. Spearman rank correlation coefficients (r) were calculated and two-tailed paired t tests were performed to compare the SUVmax and SUVmean values obtained from CTAC with those from MRAC.

Results

The mean time after FDG injection was 66?±?7 min for PET/CT and 117?±?15 min for PET/MRI examination. MRAC SUV values were significantly lower than the CTAC SUV values in mediastinal blood pool (p?<?0.001 for both SUVmax and SUVmean) and liver (p?=?0.01 for SUVmean). The MRAC SUV values were significantly higher in bone marrow (p?<?0.001 for both SUVmax and SUVmean), psoas major muscle (p?<?0.001 for SUVmax), and left ventricular myocardium (p?<?0.001 for SUVmax and p?=?0.01 for SUVmean). For the other normal structures, no significant difference was observed. When comparing SUV values generated from CTAC versus MRAC, high correlations between CTAC and MRAC were observed in myocardium (r?=?0.96/0.97 for SUVmax/mean), liver (r?=?0.68 for SUVmax), bone marrow (r?=?0.80/0.83 for SUVmax/mean), lung tissue (r?=?0.70 for SUVmax), and mediastinal blood pool (r?=?0.0.68/.069 for SUVmax/mean). Moderate correlations were found in lung tissue (r?=?0.67 for SUV mean), liver (r?=?0.66 for SUVmean), fat (r?=?0.48/0.53 for SUVmax/mean), psoas major muscle (r?=?0.54/0.58 for SUVmax/mean), and iliacus muscle (r?=?0.41 for SUVmax). Low correlation was found in iliacus muscle (r?=?0.32 for SUVmean).

Conclusions

Using the automatic three-segment model, our study showed high correlation for measurement of SUV values obtained from MRAC compared to those from CTAC, as the reference standard. Differences observed between MRAC and CTAC derived SUV values may be attributed to the time-delay between the PET/CT and PET/MRI scans or biologic clearance of radiotracer. Further studies are required to assess SUV measurements when performing different MR attenuation correction techniques.     

Deep learning-guided estimation of attenuation correction factors from time-of-flight PET emission data

PurposeAttenuation correction (AC) is essential for quantitative PET imaging. In the absence of concurrent CT scanning, for instance on hybrid PET/MRI systems or dedicated brain PET scanners, an accurate approach for synthetic CT generation is highly desired. In this work, a novel framework is proposed wherein attenuation correction factors (ACF) are estimated from time-of-flight (TOF) PET emission data using deep learning.MethodsIn this approach, referred to as called DL-EM), the different TOF sinogram bins pertinent to the same slice are fed into a multi-input channel deep convolutional network to estimate a single ACF sinogram associated with the same slice. The clinical evaluation of the proposed DL-EM approach consisted of 68 clinical brain TOF PET/CT studies, where CT-based attenuation correction (CTAC) served as reference. A two-tissue class consisting of background-air and soft-tissue segmentation of the TOF PET non-AC images (SEG) as a proxy of the technique used in the clinic was also included in the comparative evaluation. Qualitative and quantitative PET analysis was performed through SUV bias maps quantification in 63 different brain regions.ResultsThe DL-EM approach resulted in 6.1 ± 9.7% relative mean absolute error (RMAE) in bony structures compared to SEG AC method with RMAE of 16.1 ± 8.2% (p-value <0.001). Considering the entire head region, DL-EM led to a root mean square error (RMSE) of 0.3 ± 0.01 outperforming the SEG method with RMSE of 0.8 ± 0.02 SUV (p-value <0.001). The region-wise analysis of brain PET studies revealed less than 7% absolute SUV bias for the DL-EM approach, whereas the SEG method resulted in more than 14% absolute SUV bias (p-value <0.05).ConclusionsQualitative assessment and quantitative PET analysis demonstrated the superior performance of the DL-EM approach over the segmentation-based technique with clinically acceptable SUV bias. The results obtained using the DL-EM approach are comparable to state-of-the-art MRI-guided AC methods. Yet, this approach enables the extraction of interesting features about patient-specific attenuation which could be employed not only as a stand-alone AC approach but also as complementary/prior information in other AC algorithms.     

Artifactual 2-deoxy-2-[(18)F]fluoro-D-glucose localization surrounding metallic objects in a PET/CT scanner using CT-based attenuation correction.

PURPOSE: To communicate a clinically important artifact in positron emission tomography (PET) images using a PET/computerized tomography (CT) scanner with CT-based attenuation correction. PROCEDURE: A 65-year-old man with a maxillary sinus squamous cell carcinoma was injected with 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) and underwent a PET scan using a dual modality PET/CT scanner with CT-based attenuation correction. Immediately afterward, the patient had a second scan using a different PET scanner that used a high-energy transmission source for attenuation correction. RESULTS: The PET/CT scanner images demonstrated a focus of activity in the attenuation corrected PET images corresponding to a pacemaker in the left chest wall. No abnormal focus was noted in the nonattenuation corrected PET images. The patient had no signs or symptoms of inflammation at the site. A second scan using a PET scanner with a high-energy transmission source demonstrated no abnormal focus in the AC PET images. CONCLUSIONS: PET/CT scanners using CT-based attenuation methodology can overcorrect dense objects resulting in hot spot artifacts in AC PET images.     

CT用于PET衰减校正技术的研究进展

利用CT对PET进行衰减校正(CTAC)具有扫描时间短、噪声低等优势.实现CTAC的关键在于准确地将X线衰减系数转换为511 keV射线的衰减系数.目前的转换算法主要包括比例缩放法、分割法、双值组合法、双线性法和双能CT法.本文详细介绍这些算法的原理,综述各种算法的优缺点,并对未来CTAC算法的发展动态进行评述.     

Standardized Uptake Values in 2-Deoxy-2-[18F]Fluoro-D-Glucose with Positron Emission Tomography. Clinical Significance of Iterative Reconstruction and Segmented Attenuation Compared with Conventional Filtered Back Projection and Measured Attenuation Correction.

PURPOSE: To evaluate the clinical significance of differences in 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) lymph node standardized uptake values (SUV) in human immunodeficiency virus (HIV) infection using iterative reconstruction with segmented attenuation correction (IR SAC) compared to filtered back-projection with measured attenuation correction (FBP MAC). PROCEDURES: Seven patients with HIV infection and multiple focal lymph node abnormalities were investigated with whole-body FDG-PET. Mean and maximum SUVs from lymph node regions of interest (n = 961) were compared for quantitative differences between reconstruction techniques. RESULTS: IR MAC resulted in significantly lower mean SUV [0.06; 95% (confidence interval (CI)) = 0.04-0.07] and maximum SUV (0.82; 95% CI = 0.77-0.88) values compared to FBP MAC. With IR, segmentation of attenuation correction (AC) resulted in significantly higher mean SUV (0.12; 95% CI = 0.11-0.13) and maximum SUV (0.21; 95% CI = 0.18-0.23) values compared to IR MAC. The overall effect of both IR and SAC was a slight but significant increase in mean SUV (0.06; 95% CI = 0.06-0.08; bias = 2.1%) and a significant decrease in maximum SUV (0.62; 95% CI = 0.56-0.67) compared to FBP MAC. CONCLUSIONS: With our reconstruction parameters, significant differences in mean and maximum SUV values were observed. The magnitude of the mean SUV difference, however, was small. IR SAC is a promising method to accurately quantify standardized uptake values for clinical use.     

乳腺密度、年龄和更年期状态对正常乳腺摄取18F-FDG的影响

目的 通过SUV评价乳腺密度、年龄和更年期状态对正常乳腺组织摄取18F-FDG的影响.方法 62例经组织学明确诊断的乳腺癌患者,年龄32～79岁,平均(50±11)岁,其中绝经期前36例,绝经期后26例.所有患者均接受18F-FDG PET/CT扫描.根据ACR的BI-RADS标准,40例患者乳腺X线摄片密度(乳腺密度)为3或4级,而22例患者的乳腺密度为1或2级,所有乳腺X线摄片在18F-FDG PET/CT扫描前4周内获得.除了病变乳腺组织,对侧正常的乳腺组织或距离病灶较远的正常的乳腺组织也计算SUV的平均值和峰值.方法 是在正常乳腺组织中以12 mm×12 mm(9个像素)的感兴趣区(ROI)作为18F-FDG最高的摄取区域.统计学方法 采用均数间的t检验以及相关分析,P<0.05作为判定是否具有统计学差异的标准.结果 高密度乳腺正常组织中SUV的峰值和平均值分别为1.04±0.24和0.87±0.22,低密度乳腺正常组织中SUV的峰值和平均值分别为0.88±0.38和0.75±0.46.高密度正常乳腺组织中SUV的峰值和平均值均明显高于低密度正常乳腺组织(P<0.0005).SUV峰值的最高值在正常高密度和低密度乳腺组织中分别为2.0和1.5.激素水平(绝经期前后)对SUV的影响不显著(P=0.23).而且,也没有观察到年龄因素和SUV平均值及峰值间有相关关系(P=0.87).结论 正常乳腺组织中,高密度和低密度的乳腺组织中的SUV值有明显差异.尽管高密度正常乳腺组织中的SUV值较高,但是18F-FDG PET/CT对乳腺癌诊断的准确性不会受到明显影响,因为SUV峰值仍明显低于2.5的阈值;激素水平和年龄因素不会影响正常乳腺组织对18F-FDG的摄取.