9:15-9:30. A Clinical Evaluation of Segmented Attenuation Correction

Segmented attenuation correction (SAC) has been introduced as a method of reducing transmission scan times without degrading the quality of PET images. Presented are the results of a clinical evaluation of a SAC algorithm implemented on the GE Advance PET system. FDG whole body patient emission scans of eight minute duration were acquired. Dynamic transmission (Tx) scans of 5 frames and 6 minute total duration were acquired and rebinned into Tx scans of 2, 3, 4, 5 and 6 minute duration. Images (I) were generated using iterative reconstruction with measured attenuation correction (MAC) or SAC for all Tx scans-denoted as I(Tx6MAC), I(Tx6SAC), etc. Anthropomorphic phantom data was also acquired and reconstructed using the same methodology. Images were evaluated quantitatively using the normalized mean square error (NMSE) of different regions and the variance and bias of liver activity. I(Tx6MAC) served as the reference. A blinded observer ranked image quality. The NMSE increased as the Tx duration decreased; for patient images the NMSE was typically 20% and 40% greater for I(Tx3SAC) and I(Tx2SAC) than I(Tx6SAC) respectively. The NMSE of the MAC images increased much more rapidly as the Tx duration decreased. Similar trends were found for the variance in the liver. Bias in liver activity of the SAC images was approximately -8% for large patients. The observer consistently preferred SAC images over MAC images. SAC images demonstrated improved boundary delineation and reduced noise in areas of homogeneous high activity background. Areas of discordance were projected into areas of large difference between Tx and segmented Tx sinograms. This study has validated the use of SAC with short Tx scans. Images reconstructed with Tx scans of 3 minutes were not compromised with noise or severe artifacts.     

软组织内金属异物三维X线平片定位法

在日常工作中,对进入人体软组织内的金属异物,不但要准确地测量其位置和深度,而且更需要了解异物与伤口的三维空间位置关系,这对顺利取出异物、减少创伤有重要临床意义。笔者自1994年以来,采用伤口标记X线平片技术,对180例软组织内金属异物行三维定位,获得满意效果,现报告如下。1材料与方法1.1临床资料180例软组织金属异物存留者,男175例,女5例,年龄10~55岁,平均38.8岁。异物来源:机械、手工作业所致异物173例(96.1%),爆炸所致异物3例(1.7%),枪弹头3例(1.7%),医源性断针1例(0.5%)。异物存留部位:上肢72例,下肢102例,胸、腹壁8例,臀部1例。…     

9:00-9:15. Antiangiogenic Treatment with Endostatin Results in Uncoupling of Blood Flow and Glucose Metabolism in Human Tumors

Endostatin is a novel antiangiogenic agent currently in phase I trials. In the context of this trial, we are evaluating the use of non-invasive imaging with PET to determine the relationship between tumor blood flow and glucose metabolism in imaged tumors from treated patients.Ten patients have been treated with escalating daily iv Endostatin doses of 30 to 180 mg/m(2). PET images were obtained before the start of therapy and again after 28 days of treatment. Each patient was scanned with Oxygen-15 labeled water for estimation of tumor blood flow and Flourine-18 labeled FDG to estimate tumor metabolic activity. In most cases, two distinct tumor-bearing sites were analyzed in each patient. Thus, a total of 19 tumors were imaged. Regional blood flow and standard uptake values (SUV) were computed at baseline and 28 days post treatment and the percentage change in blood flow and SUV plotted as a function of Endostatin dose.Both blood flow and glucose metabolism in the imaged tumors were observed to increase in patients treated with 相似文献   

9:30-9:45. First Pass FDG Measured Blood Flow in Tumors: A Comparison with O-15 Labeled Water Measured Blood Flow

The purpose of this study was to determine if the first-pass of FDG can be used to measure regional blood flow in tumors in the absence of perfusion imaging with a known blood flow tracer.PET scans were obtained in patients being evaluated for tumor perfusion and metabolism in a Phase I dose escalating protocol for Endostatin, a novel antiangiogenic agent. A two minutes perfusion scan was done with a bolus injection of 60 mCi of O-15 labeled water followed by a 10 mCi dose of FDG and four sequential scans consisting of a first pass two minutes scan and three 15 minutes scans. Regions of interest were drawn on two tumor sites for each scan. Blood flow was computed using a one-compartment model previously published by the authors. Linear regression analysis was carried out between the first pass FDG measured blood flow and O-15 measured blood flow (Figure 1).Blood flow estimated from the first pass of FDG was linearly correlated with O-15 measured blood flow with an intercept of 0.01, slope of 0.86, and r squared regression coefficient of 0.74 (R = 0.86) for blood flow values of up to 0.6 ml/min/gm of tissue. These results suggests that in the absence of a perfusion tracer, the first pass of FDG provides an estimate of perfusion in a tumor within the limitations of incomplete extraction of FDG compared to O-15 water.     

Paragangliomas Throughout the Body: Hereditary Syndromes and Imaging Features Including 3D Cinematic Rendering

Paragangliomas are highly vascular neuroendocrine tumors that arise from embryonic neural crest cells. They may either be hormonally active (sympathetic) or silent (parasympathetic). Approximately one-third are hereditary, and patients may develop multiple paragangliomas. Presurgical planning involves medical management as well as interventional and/or surgical techniques that must address vascular supply. Contrast-enhanced CT is the best initial anatomical study and shows the hypervascularity and feeding vessels. 3D cinematic rendering using multiplanar light sources can highlight spatial relationships of a mass to adjacent structures and help in surgical planning. This article will review the clinical presentation of paragangliomas, genetic syndromes, presurgical management, and tumor behavior and imaging appearance by location with a particular emphasis on 3D cinematic rendering.     

9:15-9:30. Use of a Spherical 3-D Blob Analysis Program as a Method of Determination of Standardized Uptake Value (SUV) for Following Tumor Response to Chemotherapeutic Agents (CTA)

Malignant tumors exhibit increased glucose metabolism which can be quantitated by SUV. SUV is criticized for its variability resulting from many factors including the method of drawing region of interest (ROI) over the tumor. The most common method manually draws or places ROI on various slices displaying highest FDG activity. This time consuming method is associated with significant individual variation. We describe a more reproducible, efficient spherical 3-D blob analysis method of SUV and tumor volume (TV) determination to evaluate CTA response. The spherical 3-D Blob analysis program is a completely automated method with data processing performed using IDL (RS Inc., Colorado). A threshold value is set for the ROI; all voxels above threshold are grouped by connectivity. Grouped voxels, called "blobs", are displayed and statistics are calculated for each group. The threshold set for blob extraction and SUV determination is usually three times above background and is constant on repeat scans. Eight patients with metastatic carcinoma underwent PET/CT/MRI prior to and one week after chemotherapy. Three patients also had scans at one month. Maximum and average SUV's and TV were determined and appeared to be very reproducible when there was no clinical response or change on CT/MR. In these patients, repeat SUV's and volumes of the lesions (n = 38) varied by less than 20% of baseline. An increase/decrease in maximum SUV or TV correlated with a similar change in lesion size on CT/MR. The average SUV did not change. The spherical 3-D blob analysis program appears to be a reliable, efficient method of determining maximum SUV and volumetric measurements for following tumor response to CTA.     

The use of associated particle timing based on the D + D reaction for imaging a solid object.

Associated particle timing based on the D + D reaction has been applied for imaging a bulk sample, namely an aluminium box. The relatively low neutron energy, 2.8 MeV, allows a better spatial resolution from time-of-flight measurements. A combination of a Si detector for charged particles and an NaI(Tl) scintillator for inelastic-scatter gamma rays yielded an overall time resolution of 0.4 ns, giving a spatial resolution of better than 1 cm. A new reconstruction program was developed, yielding an image free from major artefacts.     

The F + 0 protocol for diuretic renography results in fewer interrupted studies due to voiding than the F - 15 protocol.

Timing of diuretic administration is not universally standardized in renography. Over the past year, our practice has changed from F-15 administration of furosemide to an F + 0 protocol. Therefore, we have retrospectively compared these 2 cohorts to assess if the shorter interval between diuretic administration and study completion in the F + 0 study results in a greater frequency of patients able to complete the subsequent 30-min dynamic acquisition without disruption due to voiding. METHODS: We identified 108 diuretic (99m)Tc-mercaptoacetyltriglycine renograms performed in the previous 18-mo period. Three patients were given furosemide at 30 min after the radiopharmaceutical and were excluded. Twenty studies in children under 3 y of age were excluded from consideration because voiding is neither restricted in this age group nor does voiding into a diaper cause disruption. Forty milligrams of furosemide were administered to adults, whereas 0.5 mg/kg was given to children. In the first cohort of 56 studies, radiopharmaceutical was administered 15 min after furosemide (F-15), whereas, in the second cohort of 29 patients, it was administered immediately thereafter (F + 0). In all cases, patients were asked to void proximal to radiopharmaceutical injection. Dynamic images and renogram curves were inspected for evidence of interruption or voiding midstudy. Statistical significance was determined by a 1-tailed Fisher exact test for proportions, with P < 0.05. RESULTS: The F-15 and F+0 groups of patients were comparable in terms of age, sex, and diuretic amount. In 17 of the F-15 patients, renography was interrupted because of voiding (30%), whereas this occurred in only 3 of the F + 0 patients (10%). This difference was significant at the P = 0.033 level. The mean time of voiding was 18.3 min (range, 12-25 min) for F-15 patients and 16 min (range, 12-19 min) for the F + 0 group. CONCLUSION: The F + 0 renal diuretic protocol is associated with a significantly lower rate of disruption because of voiding than the F-15 protocol, likely due to the shorter period between diuretic administration and study termination, which results in less bladder distention and discomfort. On the basis of these data, the F + 0 protocol appears to be a more tolerable procedure.     

3D MIA DICOM数据分析软件对心腔容积定量评估的准确性分析

目的 评价3D MIA DICOM数据分析软件对心腔容积定量评估的准确性.材料与方法对10个新鲜猪心和10例经心脏超声检查后的住院患者行64排螺旋CT心脏扫描,采用3D MIA DICOM数据分析软件分析并测量猪心的右心室容积和患者左室心腔容积,分析3D MIA DICOM数据分析软件测昔值与猪心实际容积和人体心脏超声测量值之间的相关性.结果 3D MIA DICOM软件所测猪心的右室容积和人体心脏舒张末期左室容积与物理测量值及心脏超声测量值之间具有很好的相关性(r1=0.94,r2=0.97),Altman and Bland一致性分析表明二者具有高度的一致性.结论 3D MIA DICOM数据分析软件为定量分析心腔容积提供了一种无创、简单可行且准确町信的新方法.     

基于双能量CT后处理单能谱模式对肾周脂肪粘连的有效识别及3D打印研究

目的 采用双能量CT(DECT)后处理单能谱(Mono+)模式实现对肾周脂肪粘连(APF)的有效识别及3D打印研究。方法 前瞻性搜集本院泌尿外科于2020年2月至2021年1月间拟行肾部分切除术(PN)的T1期(RENAL评分≥7分)肾癌患者86例,随机分为3D打印组(A组,41例)和常规CT图像组(B组,45例),所有患者均行DECT肾脏三期动态增强扫描,并将A组生成的DICOM格式文件传至DECT后处理工作站,选取Mono+模式对肾周脂肪情况进行识别,并将数据导入至全息可视化3D重组软件,分别进行3D建模及3D打印;B组采用常规CT薄层图像,并以传统胶片的形式进行结果发布。对两组患者的一般人口学特征、围手术期结果进行比较。结果 两组患者的一般人口学特征未见明显差别;采用DECT后处理Mono+模式可有效识别APF,并通过3D打印技术对其进行打印展示;A组在成功实施PN例数上明显多于B组(P<0.05),A组在手术时间、热缺血时间及估计失血量均少于B组(P均<0.001)。结论 基于DECT后处理Mono+模式功能可有效预测APF的发生,并采用3D打印技术对APF区域进行...     

肾动脉高分辨力三维增强磁共振血管成像术:透视触发和并行采集技术使用初探

目的:评估透视触发和并行采集技术用于肾动脉高分辨力三维增强磁共振血管成像术的可行性和对肾动脉的显影诊断效果。方法:90例临床诊断或怀疑肾动脉或腹主动脉病变的患者行高分辨力肾动脉三维增强磁共振血管成像(3D CE MRA)。使用透视触发软件启动肾动脉3D CE MRA扫描,扫描采用K空间中心填充法和加速因子为2的并行采集技术。分析图象质量和病变显示情况,并与其它检查结果对照。结果:肾动脉3D CE MRA显示了90例患者共810支动脉段(100%显示率),平均显示等级为3.88。3D CE MRA显示8例11支副肾动脉,显示等级均为4.0。肾动脉段级分支的显示率为73%(66/90例)。所有病例在动脉显示区静脉均未显影或显影很淡,平均等级为0.20。3D CE MRA发现639支动脉段正常;66支动脉段管壁不规则;55支动脉段轻度狭窄;37支动脉段严重狭窄;2支动脉段闭塞;11支动脉段动脉瘤形成。其中96支肾动脉存在狭窄,11支副肾动脉均正常。共有43例病例,肾动脉3D CE MRA与其它血管成像技术作了比较,3D CE MRA的检查结果与之完全符合。结论:透视触发并行采集肾动脉高分辨力3D CE MRA简单可行,成像时间短,空间分辨力高,能清楚显示肾动脉且无静脉污染。     

Identification of the Inflow Zone of Unruptured Cerebral Aneurysms: Comparison of 4D Flow MRI and 3D TOF MRA Data

BACKGROUND AND PURPOSE:The hemodynamics of the inflow zone of cerebral aneurysms may be a key factor in coil compaction and recanalization after endovascular coil embolization. We performed 4D flow MR imaging in conjunction with 3D TOF MRA and compared their ability to identify the inflow zone of unruptured cerebral aneurysms.MATERIALS AND METHODS:This series comprised 50 unruptured saccular cerebral aneurysms in 44 patients. Transluminal color-coded 3D MRA images were created by selecting the signal-intensity ranges on 3D TOF MRA images that corresponded with both the luminal margin and the putative inflow.RESULTS:4D flow MR imaging demonstrated the inflow zone and yielded inflow velocity profiles for all 50 aneurysms. In 18 of 24 lateral-projection aneurysms (75%), the inflow zone was located distally on the aneurysmal neck. The maximum inflow velocity ranged from 285 to 922 mm/s. On 4D flow MR imaging and transluminal color-coded 3D MRA studies, the inflow zone of 32 aneurysms (64%) was at a similar location. In 91% of aneurysms whose neck section plane angle was <30° with respect to the imaging section direction on 3D TOF MRA, depiction of the inflow zone was similar on transluminal color-coded 3D MRA and 4D flow MR images.CONCLUSIONS:4D flow MR imaging can demonstrate the inflow zone and provide inflow velocity profiles. In aneurysms whose angle of the neck-section plane is obtuse vis-a-vis the imaging section on 3D TOF MRA scans, transluminal color-coded 3D MRA may depict the inflow zone reliably.

Although endovascular coil embolization has become a major tactic to address cerebral aneurysms, recanalization or recurrence, which may result in rebleeding, are important problems. Recanalization was reported in 6.1%–39.8% of patients who had undergone endovascular treatment,^1–6 and a meta-analysis found that 20.8% of treated aneurysms recurred.³ The rate of rerupture after endovascular treatment for ruptured aneurysms has ranged from 0.11% to 5.3%,^1,4,6 and the rupture rate in the first year after coil embolization was reported as 2.5%⁷ and 2.2%.⁸ Because hemodynamics acting on the aneurysmal inflow zone may play a key role in the development of coil compaction or recanalization after endovascular coil embolization, the aneurysmal inflow zone must be packed densely to preserve the durability of aneurysm obliteration and to prevent rerupture.^9–15The inflow through the aneurysmal neck into the dome can be seen on 3D TOF MRA images.^13,16,17 Satoh et al,^16,17 who used conventional 3D TOF MRA techniques to select threshold ranges based on the signal intensity of the volume-rendering data, determined the spatial signal-intensity distribution in aneurysms. They developed transluminal color-coded 3D MRA (TC 3D MRA) to improve visualization of the aneurysmal inflow. More recently, 4D flow MR imaging based on time-resolved 3D cine phase-contrast MR imaging techniques was used to evaluate the hemodynamics of cerebral aneurysms.^18–27 However, 4D flow MR imaging requires additional time for data acquisition, and TC 3D MRA may be a convenient alternative to 4D flow MR imaging for identifying the aneurysmal inflow zone.Here, we compared the ability of 4D flow MR imaging and TC 3D MRA to identify the inflow zone of cerebral aneurysms.     

3D magnetization-prepared true-FISP: a new technique for imaging coronary arteries.

The purpose of this work was to develop an ECG-triggered, segmented 3D true-FISP (fast imaging with steady-state precession) technique to improve the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of breath-hold coronary artery imaging. The major task was to optimize an appropriate magnetization preparation scheme to permit saturation of the epicardial fat signal. An alpha/2 preparation pulse was used to speed up the approach to steady-state following a frequency-selective fat-saturation pulse in each heartbeat. The application of dummy cycles was found to reduce the oscillation of the magnetization during data acquisition. The fat saturation and magnetization preparation scheme was validated with simulations and phantom studies. Volunteer studies demonstrated substantially increased SNR (55%) and CNR (178%) for coronary arteries compared to FLASH (fast low-angle shot) with the same imaging time. In conclusion, true-FISP is a promising technique for coronary artery imaging.