Vessel enhancement filtering in three-dimensional MR angiograms using long-range signal correlation

Small vessels in three-dimensional MR angiograms have low visibility in maximum-intensity projection images because of their low contrast. In a previous study, we had two nonlinear filters that appeared to give significant improvement in small vessel detail. In this paper, we report on a generalization of this filter that allows a more general modeling of the vessels and a more complete suppression of background. One implementation of the general filter gave a vessel mean contrast-to-noise ratio that is 2.52 and 3.51 times higher than the vessel mean contrast-to-noise ratio obtained using our previously reported maximum-minimum (max-min) filter and cross- section filter, respectively.     

改进虎杖、鸡血藤炮制方法的研究

对虎杖、鸡血藤作了切制、干燥时间和成品、主要成分及水浸出物的比较。结果表明,趁鲜切片优于传统切块、再切片,既能提高饮片的规格质量和成分含量,亦能减少重复劳动,节约能源,避免药材的浪费。     

Teaching medical students about the appropriateness of social and sexual contact between doctors and their patients: evaluation of a programme

The purpose of this study was to assess the impact of an educational intervention on medical students' attitudes toward social and sexual contact with patients by doctors from three medical specialties (general practice, obstetrics/gynaecology and psychiatry). Medical students from two consecutive fifth year classes at one medical school participated in one 3 hour session that included instruction on the standards of the profession that prohibit doctor–patient sexual contact. Students were assigned to either intervention groups or control groups and responded to an anonymous questionnaire (overall response rate 66·8% ; n=141). As many as 14·5% of control group students thought it was (sometimes or usually) appropriate for general practitioners to date their own patients and at least 3% thought it appropriate for members of any of these three medical specialties to engage in sexual contact with their own patients. However, there were no significant differences in attitudes toward hugging, dating or sexual contact with current patients between those who had attended the seminar and the control groups. The session significantly influenced attitudes regarding obstetrician/gynaecologists and psychiatrists hugging and having sexual contact with former patients. These findings are discussed in relation to a need for expansion of such instruction.     

Teaching sociology of medicine: the group process

As a part of any curriculum reorganization, new instructional methods are also tested. When the University of Turku sociology of medicine course was found to need renovation, its goals and objectives, content and instructional methods were closely examined and modified, in order to strengthen institutional and multiprofessional relations and reinforce sociocultural issues in doctors' competence with the patient. This paper discusses this change, emphasizing teaching and learning methodology.     

In vivo comparison of two through-plane MR velocity mapping methods: Fast fourier encoding and phase mapping

Magnetic resonance imaging maps of velocity were acquired with a 1.5-T system in 10 subjects in a plane perpendicular to the main pulmonary artery. Velocity images were successively acquired with a method developed from Fourier-encoding velocity imaging (FEVI) principles with eight gradient steps and one excitation, and with two-point phase-subtraction mapping. Reconstruction in FEVI was implemented by zero-filling interpolation around the eight gradient steps and then around the four central steps. The methods were compared by using estimates of noise in velocity measurements based on the difference between the experimental map and a smooth fitted map. For the same acquisition time, FEVI with four encoding steps was more precise in velocity measurements than phase mapping. Precision was further increased by the use of eight encoding steps, but acquisition time was doubled.     

腹部CTA检查的质量保证

目的:探讨螺旋CT血管造影(Spiral CT angiography,SCTA)技术,以期提高SCTA造影的质量。材料与方法:采用Somatom Plus 4螺旋CT扫描系统对10例病人行腹部SCTA检查。扫描技术和造影剂参数按病变范围和性质而定,三维重建采用最大强度投影法(MIP)或表面阴影显示法(SSD)或弯曲平面重建法(CPR)。结果:SCTA检查技术能可靠地显示血管形态和病变,评价腹部肿瘤与邻近血管关系。结论:SCTA是无创伤性的血管成像术,在很大范围可替代创伤性的血管造影。     

Dopamine receptor agonists alter gap prestimulus modulation

An innocuous sensory event (a prestimulus) that briefly precedes a startle-eliciting stimulus (SES) will reduce the amplitude of the subsequently elicited reflex. In three experiments brief silent periods in otherwise continuous noise (gaps) were used as prestimuli to investigate the effects of the D₁ dopamine receptor agonist (±)-SKF-38393 (SKF) and the dopamine D₂ receptor group agonist (−)-quinpirole hydrochloride on gap inhibition of the rat’s acoustic startle reflex. Gap durations of 4 and 50 ms were analyzed. Quinpirole (0–1.6 mg/kg) had a biphasic effect on gap inhibition. Lower doses increased gap inhibition, an effect that peaked at the 0.4 mg/kg dose. For higher doses, inhibition returned to control levels for the 4-ms long gap, but remained elevated for the 50-ms long gap. SKF had no effect on gap inhibition, and haloperidol (0.2 mg/kg) reversed the quinpirole-induced increase of gap inhibition. These data implicate the D₂ dopamine receptor group in gap inhibition of startle modulation. The results are discussed in terms of the effects of catecholamine agonists on attention. Received: 25 July 1995/Final version: 28 April 1997     

An analysis of paediatric diagnostic decision-making: how should students be taught?

This study assesses the relative importance of history, examination and investigations in paediatric diagnosis, in the Paediatric Out-patient Department of the Central Middlesex Hospital, London, by means of a questionnaire-based record of 94 consecutive referrals. A diagnosis identical to the final diagnosis was made in 76% of referrals after taking a history. The general practitioner had proposed a diagnosis in 45% in the referral letter. Clinical examination changed the diagnosis in only 15% but increased diagnostic confidence in 33%. Ninety-one per cent of cases were diagnosed without recourse to investigations. Forty-two per cent of children referred had investigations performed. In the majority of paediatric cases the provisional diagnosis reached after taking a history was identical to that after examination or results of investigations were known. Although examination provided a final diagnosis in only 15% of all cases it played an important role in adding confidence in 33%. More educational effort should therefore be directed at clinical history-taking skills and the subsequent purpose of examination.     

16株假单胞菌DNA的G＋C百分含量测定

采用改良的热变性温度法，将DNA升温及恒温处理与紫外吸收值的测定分两步进行，检测3株标准菌株和16株假单胞菌DNA的G Cmol% 含量。结果表明，14株假单胞菌与其相应标准菌种的DNAG＋Cmol%含量基本一致，与其生物学性状亦相符；另2株DNA的G＋Cmol%含量与其生物学性状不符，其分类学位置尚待探讨。