基于“3面9点”配准方案的PET+MRI异机二维图像融合尝试

目的:尝试一种基于体表定位的二维图像配准方法,实现PET和MRI异机图像的精确融合。方法:输入PET/MRI原始数据后采用数字化格式转换,设计"3面9点"立体定位法进行配准,在实时工作站Mimics按照信息交互自动融合模式,通过讯号叠加技术完成图像融合。结果:以肺癌患者的胸部和髋部为实例交叉试验PET+MRI二维图像的异机融合,生成同时呈现胸髋解剖结构和代谢状况的互补影像。结论:在同机设备成本昂贵、不易普及的条件下,这种异机融合无疑是现有同机成像的必要补充。     

正电子发射断层成像与计算机断层扫描的异机三维融合影像分析

目的尝试一种基于特征定位的三维图像配准方法,实现正电子发射断层成像(PET)与计算机断层扫描(CT)异机三维(3D)图像的精确融合。资料与方法输入PET/CT的DICOM数据后,经过三维重建和虚拟"切割",寻找人体"内部特征点",结合预选的"外部特征点"以供下一步的混合"对焦",遵循"特征提取"、"图像对位"的步骤,实施"循点择面、循面分割"。这一"9点3面"立体定位配准方案的设计首先在几何学上被证明理论可行,并在实时工作站Mimics通过信息交互自动融合模式和讯号叠加技术使图像融合最终实现。结果以肿瘤患者为例试验[PET+CT]3D图像的异机融合,生成了同时呈现代谢状况和解剖结构的互补3D影像,获得54%的检出率,虽在定量分析方面低于2D同机[PET+CT]的检出率,但在定性分析角度具备同机[PET+CT]所没有的视觉功用。结论在[PET+CT]联机设备尚未普及尤其是[PET+CT]立体融合仍未实现的状况下,[PET+CT]异机3D融合是同机[PET+CT]2D融合功能的必要的技术补充。     

SPECT与CT3D图像异机融合的实验研究

目的:初步探讨SPECT与CT图像异机融合.方法:利用核医学质控PET-CT模型,分别使用SPECT、64排CT、SPECT/CT分别进行采集,然后利用MIPAV软件对SPECT、64排CT图像进行异机融合.以SPECT/CT PET-CT模型同机融合图像为金标准,视觉评价异机融合图像质量.结果:利用M1PAV软件可将SPECT和64排CT所采集PET-CT模型图像较为理想地进行异机融合.由影像科医师对异机融合图像与同机融合图像进行比较,图像质量无显著差异.结论:对于SPECT和CT所采集图像,利用MIPAV软件进行3D图像异机融合具有临床可行性.     

床位变化对SPECT/CT同机图像配准的影响

目的探讨检查床在有、无负重,不同负重状态下,硬件配准误差对单光子发射计算机断层成像技术/计算机体层摄影(SPECT/CT)同机融合图像质量的影响。材料与方法制作放射线源模型,在检查床有、无负重,负重不同状态下分别进行SPECT/CT图像采集,进行同机图像融合后用图像软件分析并测量SPECT与CT融合图像偏差程度。结果检查床上0负荷时同机图像融合配准较准确,两种图像中心偏移平均2mm。加载50kg与100kg重量后,床位移动过程中Y轴会出现偏差,最大偏差为4.3mm,平均偏差为2.3mm,但差异无统计学意义(P>0.05)。结论在负重状态下床位变化导致SPECT/CT同机图像融合配准有细微偏差,但不会影响图像融合质量。     

呼气中期屏气CT扫描对PET/CT图像质量和肺组织SUV的影响

目的 探讨呼气中期屏气CT扫描模式对PET/CT图像质量及肺组织SUV的影响.方法 将2010年9月至12月间序列完成18F-FDG PET/CT显像的200例常规受检者纳入研究,其中男120例,女80例,年龄23～87(55.01±11.60)岁.所有受检者按随机数字表法分成2组:平静呼气中期屏气行PET/CT之同机CT采集组[屏气组,男52例,女48例,29～ 83(55.43±10.38)岁]和自由平静呼吸行PET/CT之同机CT采集组[自由呼吸组,男68例,女32例,23 ～ 87(55.68± 12.72)岁],每组各100例.图像分析由核医学科1位资深技师和2位资深医师评判.分析所有PET/CT的PET和CT空间配准、肺底部肺组织SUV和CT图像中肺部呼吸运动伪影等.以PET和CT在同一层面出现膈顶为两者空间配准良好,反之为配准不良.采用SPSS 17.0软件对数据进行统计分析,不同组SUV间差异比较采用两样本t检验或单因素方差分析,率的比较采用x2检验.结果 屏气组同机CT肺组织呼吸伪影发生率(28％,28/100)明显低于自由呼吸组(96％,96/100; x2=98.132,P＜0.01).屏气组PET/CT的PET和CT空间配准良好率(40％,80/200)明显高于自由呼吸组(30％,60/200;x2=4.396,P＜0.05).CT图像上出现膈顶先于PET、PET和CT膈顶位置配准良好和PET图像上出现膈顶先于CT 3种情况的肺底部组织的SUV逐项递增,屏气组(对应的SUVmax分别为0.73±0.28、1.00±0.29和1.60±0.68,SUVmean分别为0.59±0.23、0.81±0.22和1.33±0.34;F=21.93和24.57,均P＜0.01)此现象较自由呼吸组明显(对应的SUVmax分别为0.84±0.36、1.08±0.27和1.16±0.24,SUVmean分别为0.69±0.29、0.85±0.20和0.94±0.24;F=7.23和6.29,均P＜0.01).结论 呼气中期屏气CT扫描简便易行,不增加辐射剂量,可明显降低同机CT呼吸运动伪影发生率,在一定程度上提高PET和CT图像空间配准率.PET和CT失配准膈肌位置不同可导致低估或高估肺组织SUV.     

SPECT/CT同机融合显像对肿瘤患者骨转移灶的诊断价值

目的:评价SPECT/CT同机融合显像对单独SPECT难于确诊良恶性的骨病灶的鉴别诊断价值.方法:SPECT骨扫描难于确诊的对53例肿瘤患者的84个病灶行局部SPECT/CT同机融合断层显像.所有患者转移灶确诊以临床病理、MRI、CT、骨扫描复查或PET/CT检查为依据.结果:①SPECT显像无法确诊的84个病灶,经S...     

18F-FDG SPECT/CT显像与64排螺旋CT异机融合技术在胃癌诊断中的应用

目的通过对比分析18F-FDG SPECT/CT与64排螺旋CT异机融合的图像质量,探讨异机融合在胃癌诊断中的优势。 方法收集一周内分别行18F-FDG SPECT/CT和64排螺旋CT扫描的符合入选标准的35例胃癌患者,共计56枚病灶,其中包含胃部肿瘤病灶28枚、转移淋巴结病灶19枚和远处转移病灶9枚,并依此进行分组,同组中同机融合的图像与异机融合的图像进行图像质量对比,分别从病灶的大小、边界是否清晰、是否有伪影等方面进行主观综合评价、分级。两组间计数资料比较采用卡方检验。 结果在胃部肿瘤病灶组中,28枚病灶同机融合后图像质量为1、2、3级的病灶数量分别为8、14、6枚,异机融合分别为25、3、0枚;在转移淋巴结病灶组中,19枚病灶同机融合后图像质量为1、2、3级的病灶数量分别为7、5、7枚,异机融合分别为17、2、0枚;在远处转移病灶组中,9枚病灶同机融合后图像质量为1、2、3级的病灶数量分别为0、3、6枚,异机融合分别为8、1、0枚。3组中同机融合与异机融合图像质量比较差异均有统计学意义（χ2=21.875、12.452和15.000,均P < 0.05）,异机融合后的图像质量优于同机融合。 结论18F-FDG SPECT/CT与64排螺旋CT异机融合的图像质量明显优于同机融合,在胃癌诊断中能提供更好的诊断依据,值得临床推广应用。     

18F-FDG PET/CT的特点及其在肿瘤诊断中的应用

最近几年,具有高性能PET和CT的同机PET/CT已投入临床,其在肿瘤学中的应用呈迅速增长之势.加入高档CT的PET较之传统的PET在技术和临床方面具有明显优势.CT扫描一方面为PET提供了快速、准确的衰减校正数据,大大缩短采集时间,另一方面为PET图像提供了精确的解剖定位,使结果更加肯定,但引入CT的PET扫描也带来了一些技术上的新问题.PET/CT在头颈、腹盆肿瘤具有明显优势,即使在生理运动影响较大的胸部也取得了满意的效果.初步临床研究表明,PET/CT较之单独CT或PET在临床肿瘤学中具有明显优势,PET/CT融合显像对肿瘤患者和临床医生具有越来越重要的价值.     

磁共振成像与CT图像融合技术在喉癌精确放疗定位中的初步应用

目的 探讨磁共振成像(MRI)和CT图像融合技术对喉癌精确放疗定位的应用价值及意义.方法 对10例经内镜及手术病理证实的喉癌患者行图像融合,先行CT定位薄层扫描,然后行颈部MRI定位薄层扫描,最后将MRI图像资料拷贝至图像融合工作站进行配准和融合.结果 所有病变在融合的图像上均能清楚显示并配准满意,MRI薄层扫描可以大大弥补CT定位扫描中软组织分辨率低,病变显示范围不足的缺点,对进一步精确放疗提供可靠的信息.结论 MRI薄层扫描可以弥补CT定位图像在喉部软组织病变的显示不清晰的缺点,提高了喉癌放疗定位的精确性.     

PET/CT:当前研究和应用新进展

PET/CT实现了PET与CT同机图像融合,为肿瘤显像提供了一种新的诊断技术。本文简要介绍PET/CT有关的几个技术问题和临床应用方面的新进展,如晶体的选择、CT技术进展、放射治疗、衰减校正、呼吸运动及CT造影剂的影响等。     

Clinical significance of creative 3D-image fusion across multimodalities [PET+CT+MR] based on characteristic coregistration

Objective

To investigate a registration approach for 2-dimension (2D) based on characteristic localization to achieve 3-dimension (3D) fusion from images of PET, CT and MR one by one.

Method

A cubic oriented scheme of“9-point &; 3-plane” for co-registration design was verified to be geometrically practical. After acquisiting DICOM data of PET/CT/MR (directed by radiotracer ¹⁸F-FDG etc.), through 3D reconstruction and virtual dissection, human internal feature points were sorted to combine with preselected external feature points for matching process. By following the procedure of feature extraction and image mapping, “picking points to form planes” and “picking planes for segmentation” were executed. Eventually, image fusion was implemented at real-time workstation mimics based on auto-fuse techniques so called “information exchange” and “signal overlay”.

Result

The 2D and 3D images fused across modalities of [CT + MR], [PET + MR], [PET + CT] and [PET + CT + MR] were tested on data of patients suffered from tumors. Complementary 2D/3D images simultaneously presenting metabolic activities and anatomic structures were created with detectable-rate of 70%, 56%, 54% (or 98%) and 44% with no significant difference for each in statistics.

Conclusion

Currently, based on the condition that there is no complete hybrid detector integrated of triple-module [PET + CT + MR] internationally, this sort of multiple modality fusion is doubtlessly an essential complement for the existing function of single modality imaging.     

Automatic arm removal in PET and CT images for deformable registration

Positron emission tomography (PET) imaging is rapidly expanding its role in clinical practice for cancer management. The high sensitivity of PET for functional abnormalities associated with cancer can be confounded by the minimal anatomical information it provides for cancer localization. Computed tomography (CT) provides detailed anatomical information but is less sensitive to pathologies than PET. Thus, combining (i.e., registering) PET and CT images would enable both accurate and sensitive cancer localization with respect to detailed patient anatomy. An additional application area of registration is to align CT–CT scans from serial studies on a patient on a PET/CT scanner to facilitate accurate assessment of therapeutic response from the co-aligned PET images. To facilitate image fusion, we are developing a deformable registration software system using mutual information and a B-spline model of the deformation. When applying deformable registration to whole body images, one of the obstacles is that the arms are present in PET images but not in CT images or are in different positions in serial CT images. This feature mismatch requires a preprocessing step to remove the arms where present and thus adds a manual step in an otherwise automatic algorithm. In this paper, we present a simple yet effective method for automatic arm removal. We demonstrate the efficiency and robustness of this algorithm on both clinical PET and CT images. By streamlining the entire registration process, we expect that the fusion technology will soon find its way into clinics, greatly benefiting cancer diagnosis, staging, therapy planning and treatment monitoring.     

Registration of chest PET and CT images-fusion technique using the PET/Tr image by the respiration compensation

OBJECTIVE: The conventional registration of PET images of the chest with CT images is performed by rotating and shifting those images while used median lines and contours on axial images as the reference indexes. For the thoracic and the abdominal regions, therefore, the respiratory movements have prevented us from achieving satisfactory levels of registration reproducibility and accuracy. In order to solve this, we have analyzed respiratory movements of the chest and derived an image fusion method. METHODS: Respiratory movements of the lung along each axis (X-axis: left-right, Y-axis: dorsoventral, and Z-axis: craniocaudal) during deep breathing were analyzed using CT-3D images. In addition, respiratory movements of the lung and thorax in the Y-axis and Z-axis directions during deep breathing and at rest were also analyzed by using an MR system that is the non-invasive method and allows for acquiring arbitrary tomographic images. Respiratory movements were compensated for on PET images of the lung. Moving average deviations in the Y-axis and Z-axis directions, which were obtained from the analytical result of respiration (30 samples), were used to derive the compensatory values. RESULTS: The analysis of CT-3D images showed that the movements in the X-axis direction were negligible. Registration of PET images with CT images was found useful when it performed on the sagittal planes. The analysis of MR images on sagittal planes revealed that the region extending from the apex of the lung to the posterior wall of the lung was useful for reference indexes for registration. The PET image by the compensation of the respiration transfer difference in the pulmonary hilum division was fusion on the CT image. In the pulmonary hilum division, the improvement in the accuracy of 3.6 mm in the dorsoventral and 6.1 mm in the craniocaudal direction was obtained in comparison with the fusion only of the reference index. CONCLUSION: The developed image fusion technique compensating the respiratory movements was found to be effective over the region of the hilum of the lung than the conventional technique.     

Three-dimensional reconstruction and fusion for multi-modality spinal images.

Medical diagnosis can benefit from the complementary information in different modality images. Multi-modal image registration and fusion is an essential task in numerous three-dimensional (3D) medical image-processing applications. Registered images are not only providing more correlative information to aid in diagnosis, but also assisting with the planning and monitoring of both surgery and radiotherapy. This research is directed at registering different images captured from Computed Tomography (CT) and Magnetic Resonance (MR) imaging devices, respectively, to acquire more thorough information for disease diagnosis. Because MR bone model segmentation is difficult, this research used a 3D model obtained from CT images. This model accomplishes image registration by optimizing the gradient information accumulated around the bony boundary areas with respect to the 3D model. This system involves pre-processing, 2D segmentation, 3D registration, fusion and sub-system rendering. This method provides desired image operation, robustness verification, and multi-modality spinal image registration accuracy. The proposed system is useful in observing the foramen and nerve root. Because the registration can be performed without external markers, a better choice for clinical usage is provided for lumbar spine diagnosis.     

Prostate cancer: sextant localization with MR imaging, MR spectroscopy, and 11C-choline PET/CT

PURPOSE: To retrospectively compare sensitivity and specificity of magnetic resonance (MR) imaging, three-dimensional (3D) MR spectroscopy, combined MR imaging and 3D MR spectroscopy, and carbon 11 (11C)-choline positron emission tomography (PET)/computed tomography (CT) for intraprostatic tumor sextant localization, with histologic findings as reference standard. MATERIALS AND METHODS: The local ethics committee on human research provided approval and a waiver of informed consent for the retrospective study. MR imaging, 3D MR spectroscopy, and 11C-choline PET/CT results were retrospectively reviewed in 26 men with biopsy-proved prostate cancer (mean age, 64 years; range, 51-75 years) who underwent radical prostatectomy. Cancer was identified as areas of nodular low signal intensity on T2-weighted MR images. At 3D MR spectroscopy, choline-plus-creatine-to-citrate and choline-to-creatine ratios were used to distinguish healthy from malignant voxels. At PET/CT, focal uptake was visually assessed, and maximum standardized uptake values (SUVs) were recorded. Agreement between 3D MR spectroscopic and PET/CT results was calculated, and ability of maximum SUV to help localize cancer was assessed with receiver operating characteristic analysis. Significant differences between positive and negative sextants with respect to mean maximum SUV were calculated with a paired t test. RESULTS: Sensitivity, specificity, and accuracy were, respectively, 55%, 86%, and 67% at PET/CT; 54%, 75%, and 61% at MR imaging; and 81%, 67%, and 76% at 3D MR spectroscopy. The highest sensitivity was obtained when either 3D MR spectroscopic or MR imaging results were positive (88%) at the expense of specificity (53%), while the highest specificity was obtained when results with both techniques were positive (90%) at the expense of sensitivity (48%). Concordance between 3D MR spectroscopic and PET/CT findings was slight (kappa=0.139). CONCLUSION: In localizing cancer within the prostate, comparable specificity was obtained with either 3D MR spectroscopy and MR imaging or PET/CT; however, PET/CT had lower sensitivity relative to 3D MR spectroscopy alone or combined with MR imaging.     

Retrospective digital image fusion of multidetector CT and 18F-FDG PET: clinical value in pancreatic lesions--a prospective study with 104 patients.

Differential diagnosis of pancreatic lesions still remains a problem. Whereas CT provides high spatial resolution, PET detects malignant lesions with high sensitivity. The objective of this study was to evaluate the clinical benefit of PET/CT image fusion in the diagnostic workup of pancreatic cancer. METHODS: One hundred four patients with suspected pancreatic lesion underwent triple-phase multidetector CT and (18)F-FDG PET scanning. Voxel-based retrospective registration and fusion of CT and PET were performed with recently developed software. CT, PET, and fused images were assessed by 2 radiologists with regard to the detection of malignancies, possible infiltration of adjacent tissue or lymph nodes, or distant metastases. RESULTS: Fusion of CT and PET images was technically successful in 96.2%. In 2 cases, paraaortic lymph node infiltration was detected only by image fusion; in a further 8 cases, lymph node metastases were confirmed with improved localization. In 5 patients, additional pancreatic tumors or distant metastases only suspected during PET scanning were confirmed. Image fusion improved the sensitivity of malignancy detection from 76.6% (CT) and 84.4% (PET) to 89.1% (image fusion). Compared with CT alone, image fusion increased the sensitivity of detecting tissue infiltration to 68.2%, but at the cost of decreased specificity. CONCLUSION: The most important supplementary finding supplied by image fusion is a more precise correlation with focal tracer hot spots in PET. Image fusion improved the sensitivity of differentiating between benign and malignant pancreatic lesions with no significant change in specificity. All image modalities failed to stage lymph node involvement.     

Evaluation of image registration in PET/CT of the liver and recommendations for optimized imaging.

Multimodality PET/CT of the liver can be performed with an integrated (hybrid) PET/CT scanner or with software fusion of dedicated PET and CT. Accurate anatomic correlation and good image quality of both modalities are important prerequisites, regardless of the applied method. Registration accuracy is influenced by breathing motion differences on PET and CT, which may also have impact on (attenuation correction-related) artifacts, especially in the upper abdomen. The impact of these issues was evaluated for both hybrid PET/CT and software fusion, focused on imaging of the liver. METHODS: Thirty patients underwent hybrid PET/CT, 20 with CT during expiration breath-hold (EB) and 10 with CT during free breathing (FB). Ten additional patients underwent software fusion of dedicated PET and dedicated expiration breath-hold CT (SF). The image registration accuracy was evaluated at the location of liver borders on CT and uncorrected PET images and at the location of liver lesions. Attenuation-correction artifacts were evaluated by comparison of liver borders on uncorrected and attenuation-corrected PET images. CT images were evaluated for the presence of breathing artifacts. RESULTS: In EB, 40% of patients had an absolute registration error of the diaphragm in the craniocaudal direction of >1 cm (range, -16 to 44 mm), and 45% of lesions were mispositioned >1 cm. In 50% of cases, attenuation-correction artifacts caused a deformation of the liver dome on PET of >1 cm. Poor compliance to breath-hold instructions caused CT artifacts in 55% of cases. In FB, 30% had registration errors of >1 cm (range, -4 to 16 mm) and PET artifacts were less extensive, but all CT images had breathing artifacts. As SF allows independent alignment of PET and CT, no registration errors or artifacts of >1 cm of the diaphragm occurred. CONCLUSION: Hybrid PET/CT of the liver may have significant registration errors and artifacts related to breathing motion. The extent of these issues depends on the selected breathing protocol and the speed of the CT scanner. No protocol or scanner can guarantee perfect image fusion. On the basis of these findings, recommendations were formulated with regard to scanner requirements, breathing protocols, and reporting.     

Diagnostic performance of fluorodeoxyglucose positron emission tomography/magnetic resonance imaging fusion images of gynecological malignant tumors: comparison with positron emission tomography/computed tomography

Purpose

We compared the diagnostic accuracy of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and PET/magnetic resonance imaging (MRI) fusion images for gynecological malignancies.

Materials and methods

A total of 31 patients with gynecological malignancies were enrolled. FDG-PET images were fused to CT, T1- and T2-weighted images (T1WI, T2WI). PET-MRI fusion was performed semiautomatically. We performed three types of evaluation to demonstrate the usefulness of PET/MRI fusion images in comparison with that of inline PET/CT as follows: depiction of the uterus and the ovarian lesions on CT or MRI mapping images (first evaluation); additional information for lesion localization with PET and mapping images (second evaluation); and the image quality of fusion on interpretation (third evaluation).

Results

For the first evaluation, the score for T2WI (4.68 ± 0.65) was significantly higher than that for CT (3.54 ± 1.02) or T1WI (3.71 ± 0.97) (P < 0.01). For the second evaluation, the scores for the localization of FDG accumulation showing that T2WI (2.74 ± 0.57) provided significantly more additional information for the identification of anatomical sites of FDG accumulation than did CT (2.06 ± 0.68) or T1WI (2.23 ± 0.61) (P < 0.01). For the third evaluation, the three-point rating scale for the patient group as a whole demonstrated that PET/T2WI (2.72 ± 0.54) localized the lesion significantly more convincingly than PET/CT (2.23 ± 0.50) or PET/T1WI (2.29 ± 0.53) (P < 0.01).

Conclusion

PET/T2WI fusion images are superior for the detection and localization of gynecological malignancies.