A computational model of rat cerebral blood flow using non-uniform rational B-splines.

Non-Uniform Rational B-splines (NURBS) surfaces can be used for a computer simulation of shapes. Some anatomical models of human or animal structures have been recently developed on that basis. We used positron-emission tomography (PET) and computed tomography (CT) data for NURBS modeling of anatomical structures and isotope uptake in the rat brain. Our simplified model of the rat cerebral blood flow is the first step in a larger project aiming a simulation of PET scans in small animals followed by its validation in vivo.

How emergency departments might alert for prehospital heat-related excess mortality?

INTRODUCTION: A major issue raised by the public health consequences of a heat wave is the difficulty of detecting its direct consequences on patient outcome, particularly because of the delay in obtaining definitive mortality results. Since emergency department (ED) activity reflects the global increase of patients' health problems during this period, the profile of patients referred to EDs might be a basis to detect an excess mortality in the catchment area. Our objective was to develop a real-time surveillance model based on ED data to detect excessive heat-related mortality as early as possible. METHODS: A day-to-day composite indicator was built using simple and easily obtainable variables related to patients referred to the ED during the 2003 heat-wave period. The design involved a derivation and validation study based on a real-time surveillance system of two EDs at Cochin Hospital and Hôtel-Dieu Hospital, Paris, France. The participants were 99,976 adult patients registered from 1 May to 30 September during 2001, 2002 and 2003. Among these participants, 3,297, 3,580 and 3,851 patients were referred to the EDs from 3 August to 19 August for 2001, 2002 and 2003, respectively. Variables retained for the indicator were selected using the receiver operating characteristic curve methodology and polynomial regression. RESULTS: The indicator was composed of only three variables: the percentage of patients older than 70 years, the percentage of patients with body temperature above 39 degrees C, and the percentage of patients admitted to or who died in the ED. The curve of the indicator with time appropriately fitted the overall mortality that occurred in the region of interest. CONCLUSION: A composite and simple index based on real-time surveillance was developed according to the profile of patients who visited the ED. It appeared suitable for determining the overall mortality in the corresponding region submitted to the 2003 heat wave. This index should help early warning of excessive mortality and monitoring the efficacy of public health interventions.

[Five-word test: insufficiently sensitive but very specific for organic memory disorders]. / Test des 5 mots: insuffisamment sensible, mais très spécifique des troubles mnésiques organiques.

OBJECTIVES: The "five-word test', derived from the Grober and Buschke test, is an easy and rapid tool to distinguish between organic disorders of memory encoding and apparent memory deficits due to inefficient information retrieval strategies. Its metrological characteristics require specification. METHODS: Subjects were classified as demented or non-demented according to DSM IV and NINCDS-ARDA criteria after a dementia assessment and a neuropsychological assessment. All subjects took the five-word test. RESULTS: In all, 142 patients took this test (81 with and 61 without dementia). It was insufficiently sensitive: 80.2% for a score of 10/10 and 60.49% for 9/10. Its specificity, however, was excellent: 100% for scores below 9/10. It also helped identify mistakes due to organic memory disorders, in the form of "intrusion" in the various tests. DISCUSSION: Although this test showed a lack of sensitivity for detecting dementia or organic memory disorders, it remains a useful tool: a pathologic score does permit affirmation of those diagnoses. CONCLUSION: The practical qualities (simplicity and rapidity of administration) of the five-word test make it an essential tool in the evaluation by geriatricians or general practitioners of cognitive disorders in the elderly.

Assessment myocardial perfusion and contraction by Karhunen-Loeve transform on scintigraphic images.

Theory and previous studies showed that KLT (an application of principal component transform for imaging) can be use for analysis of cardiac function. This paper presents the results of our studies concerning the applications of KLT for images smoothing, quantification of myocardial contraction, and improvement of inter-observer reproducibility in cardiac imaging. The paper also describes the use of 4D cardiac phantom to quantify Karhunen-Loeve images.

Poststress motionlike artifacts caused by the use of a dual-head gamma camera for (201)Tl myocardial SPECT.

UNLABELLED: When performing (201)Tl myocardial SPECT using a dual-head gamma camera on patients after exercise stress, we have observed in some a sudden increase in the counting rate between the 16th and 17th images. This increase provoked motionlike artifacts, which increased the number of false-positive findings. The aim of our study was to determine possible causes for this leap in activity. METHODS: We performed myocardial SPECT using a dual-head gamma camera on 110 patients after exercise stress: in 38 patients approximately 5 min after injection (group 1), in 43 patients approximately 14 min after injection (group 2), and in 29 patients twice, at approximately 5 and 20 min after injection (group 3). We also performed dynamic data acquisition for 10 min on 18 patients after exercise stress. We compared activity in the heart region in image series obtained after exercise stress and at rest. RESULTS: Daily quality control tests eliminated the possibility of any malfunctions of the gamma camera. Careful image analysis showed no visible patient motion. Our results showed that upward creep of the heart could not be a cause of the described phenomenon. After exercise stress, a > or = 5% activity leap in the heart region on the 16th and 17th frames was more frequent in group 1 than in group 2. Two consecutive acquisitions after exercise stress showed that the leap was >5% in 24 patients (83%) and 12 patients (41%) at the first and second acquisitions, respectively (group 3). In all patients, the leap was <5% at rest. Dynamic studies showed that the activity in the heart region steadily decreased in all patients after exercise stress. We suggest that decreasing (201)Tl concentrations in myocardium or blood could be a major reason for the described artifacts. CONCLUSION: We proposed that the pharmacokinetics of (201)Tl-chloride be evaluated within a short time after injection in humans after exercise stress. Now, in our department, we have begun acquisition approximately 12 min after (201)Tl administration, and the above-mentioned phenomenon has not appeared. However, to avoid the artifacts caused by early redistribution of (201)Tl, acquisition must not begin too late.