Ventilation-perfusion lung scans for pulmonary emboli

Reports were made on combined ventilation-perfusion lung scans by three observers on three occasions and by another observer once. Reproducibility for each observer varied between 80 and 88%. There was complete agreement about the areas of scans reported as abnormal. Agreement between observers on whether or not the abnormality represented a pulmonary embolus averaged 77%. There was 86% agreement with the final clinical diagnosis. Our results show that reporting of ventilation perfusion lung scans by eye is reproducible. They support the claims that, under routine clinical conditions, the technique is 91% to 95% accurate for pulmonary emboli.     

Gated xenon scans for right ventricular function

The complex geometry of the right ventricle makes the use of radionuclides an attractive method for assessing right ventricular function. The use of the gated 133Xe technique for this purpose offers several advantages. A short i.v. infusion over 20 sec of 133Xe permits scans to be obtained, gated to the electrocardiogram at rest and during maximal exercise using a standard gamma camera. The method is both reproducible (3.5%) and repeatable (2.8%), and because of the short half-life within the patient with most of the radioisotope being excreted by the lungs, scans may be repeated within a few minutes and the radiation dose to the patient is small. Right ventricular ejection fraction obtained from gated xenon scans is shown to correlate well with measurements obtained from both standard gated technetium scans and first-pass studies.     

A new display technique for computer-processed digital scans

This article presents a new approach for presenting scintigraphic images. The technique combines the conventional plotting of contour lines and the highlighting, by means of hatching, of the concavities (or convexities) of the surface representative of radioactive distribution. The search for the surface features is achieved generally by the method for normal curvatures. An example with a phantom demonstrates the utility of this representation method.     

Atlas of sodium fluoride PET bone scans: atlas of NaF PET bone scans

Sodium fluoride (NaF) is a bone-seeking positron-emitting tracer with high sensitivity and specificity for detection of osseous lesions, particularly osteolytic lesions. We believe that NaF positron emission tomography (PET)/computed tomography (CT) scans can provide a more thorough and conclusive evaluation of bone diseases than conventional Technetium-99m-methylene diphosphonate bone scans. Understanding both normal and pathologic patterns is important for the evaluation and interpretation of these studies. Thus, an atlas of NaF positron emission tomography/computed tomography bone scans demonstrating benign, pathologic, and malignant osseous lesions as well as extraosseous lesions will be invaluable in the correct interpretation and diagnosis of osseous lesions.     

Voxel-based analysis of 11C-PIB scans for diagnosing Alzheimer's disease

The positron emission tomography (PET) radioligand N-methyl-11C-2-(4-methylaminophenyl)-6-hydroxybenzothiazole (also known as 11C-6-OH-BTA-1 or 11C-PIB) binds to amyloid-beta (Abeta), which accumulates pathologically in Alzheimer's disease (AD). Although 11C-PIB accumulation is greater in patients with AD than in healthy controls at a group level, the optimal method for discriminating between these 2 groups has, to our knowledge, not been established. We assessed the use of data-determined standardized voxels of interest (VOIs) to improve the classification capability of 11C-PIB scans on patients with AD. METHODS: A total of 16 controls and 14 AD age-matched patients were recruited. All subjects underwent a 11C-PIB scan and structural MRI. Binding potential (a measure of amyloid burden) was calculated for each voxel using the Logan graphical method with cerebellar gray matter as the reference region. Voxel maps were then partial-volume corrected and spatially normalized by MRI onto a standardized template. The subjects were divided into 2 cohorts. The first cohort (control, 12; AD, 9) was used for statistical parametric mapping analysis and delineation of data-based VOIs. These VOIs were tested in the second cohort (control, 4; AD, 5) of subjects. RESULTS: Statistical parametric mapping analysis revealed significant differences between control and AD groups. The VOI map determined from the first cohort resulted in complete separation between the control and the AD subjects in the second cohort (P < 0.02). Binding potential values based on this VOI were in the same range as other reported individual and mean cortical VOI results. CONCLUSION: A standardized VOI template that is optimized for control or AD group discrimination provides excellent separation of control and AD subjects on the basis of 11C-PIB uptake. This VOI template can serve as a potential replacement for manual VOI delineation and can eventually be fully automated, facilitating potential use in a clinical setting. To facilitate independent analysis and validation with more and a broader variety of subjects, this VOI template and the software for processing will be made available through the Internet.     

CT扫描所致受检者器官剂量的体模实验研究

目的 了解不同部位X射线CT扫描所致受检者器官或组织的吸收剂量及其分布。方法 实测体模中重要组织器官的CT值,并转换成线性吸收系数与人体正常值进行比较;在体模中 布放光致辐射发光玻璃剂量计,分别模拟测量头部、胸部、腹部和盆腔CT扫描所致受检者主要器官或组织的吸收剂量。结果 实验用仿真人体模具有良好的组织等效性。头部扫描吸收剂量最大的器官是大脑,胸部扫描吸收剂量较大的器官是甲状腺、乳腺、肺和食道,腹部扫描吸收剂量较大的器官是肝、胃、结肠和肺,单次盆腔扫描体所致骨表面和结肠的吸收剂量可达50 mGy以上。结论 X射线CT扫描所致受检者的器官剂量及其分布随扫描部位的不同而异。盆腔扫描时结肠、红骨髓、性腺和膀胱等主要器官的吸收剂量较大,应引起注意。