Masakazu Tsuzuki

Development of interactive vessel modelling system for hepatic vasculature from MR images

THREE-DIMENSIONAL reconstructions of medical images are widely used. Although there are several established techniques, if the purpose of reconstruction is only visualisation, volume rendering is the best way (CHRISTIAN, 1993). However, in applications such as surgical support, visualisation is insufficient and a more interactive approach is required. Beyond visualisation, surgical simulation is also studied, mainly in the field of plastic surgery (UDUPA et al., 1991). In this work, we describe a technique related to a system we are developing for computer-aided surgery (CAS) (Fig. 1). The system will be used in the treatment of abdominal liver cancer (DoHI et aL, 1990; HASHIMOTO et aL, 1991) and stereotactic surgery etc. For this kind of surgery, information about blood vessels is extremely important. Grasping the anatomical structure of vessel data is indispensible. Therefore, we have developed an algorithm for hepatic vasculature reconstruction which is simple, quick and quantitative. 2 M a t e r i a l s and m e t h o d s

Sequential changes of auditory brain stem responses in relation to intracranial and cerebral perfusion pressure and initiation of secondary brain stem damage

SummaryThe relationship of supratentorial intracranial pressure (ICP) and cerebral perfusion pressure (CCP) with serial changes in auditory evoked brain stem responses was investigated. Eighty-one patients without primary brain stem damage admitted to our emergency unit were studied. When ICP over 50 mm Hg persisted for 4 hours, the I–V interpeak latency was significantly prolonged. The threshold of this prolongation was 8 hours for the ICP over 45 mm Hg and 24 hours for that of over 40 mm Hg. The ICP of 35–40 mm Hg for 24 hours was the border zone. CCP did not show a significant relation with I–V interpeak latency changes. The loss of wave V was observed in a wide range of the ICP (30–147 mm Hg) and CPP (0–60 mm Hg). Wave III disappeared when the ICP exceeded 50 mm Hg. Wave I became undetectable with an ICP above 50 mm Hg or a CPP below 40 mm Hg.These results indicate that an increase of ICP over 40 mm Hg definitely initiates secondary brainstem dysfunction if it lasts for more than 24 hours and that the ICP should be reduced below this level, preferably below 35 mm Hg, to maintain brain function. The fact that both low CPP and high ICP were involved in the loss of wave I clearly shows that both ischaemia and displacement of the brain stem are the important pathophysiological factors for the disappearance of wave I.

Coated polyglactin 910—A new synthetic absorbable suture

Physical properties of newly developed synthetic absorbable sutures, “coated polyglactin 910”, were compared with findings in two conventional synthetic absorbable sutures. Clinical results of application in 108 cases in Japan (123 clinical cases in number of tissues approximated) were also evaluated. Our findings clearly indicate that coated polyglactin 910 sutures may well become the sutures of choice for various surgical applications.

Usefulness of ICP Histogram and ICP Histogram Array in ICP Monitoring

The importance of ICP monitoring is now well recognized. It is and will remain as one of the significant subjects for the processing of ICP values and ICP waveforms, not only in the treatment of severely brain-damaged patients but also in the understanding of pathophysiology. We present a minicomputerized system of a new method for the analysis of ICP and discuss its usefulness with clinical examples.

Quantitative integration of multimodality medical images

Integration of medical images is an ever more popular topic in recent years. However, is it really possible to merge them? More precisely, in which degree is such integration reliable in a clinical and mathematical sense, and what are the criteria to accept the integration? In this study, the authors address the methodology of integration and evaluate the integrated medical images.

The Use of Model and Artificial Intelligence Techniques in Patient Monitoring

There exist a large number of techniques in patient monitoring, which have been well developed to measure physiological parameters. A skilled doctor can assess the vital level of the patient by integrating the information derived from multiple variables. The next stage will be to develop a technique which anyone can use for the aids of the diagnosis. In the previous studies Forrester et al reported to characterize patients by the haemodynamic deviation focused on the pulmonary capillary wedge pressure (PCWP) and the cardiac index (CI), proposed various kinds of drug therapy. Despite this, the natural course of haemodynamic change during the acute phase is not completely known, since most studies have not made serial measurements. Moreover, they studied only the selected groups of high risk patients, and the patients with initially less severe symptoms have not been fully represented. The aim of this study is to predict the haemodynamic change by a simple model. The advantage of the model approach is that it can manage the time-series of multiple physiological parameters systematically. The limit of it is that it cannot infer drastic change of the parameters, and the drugs are needed on that particular occasion. So the dosage of drugs still depends more or less on the doctor’s thought process. The AI-techniques will be the suitable aids of the drug therapy in the future.

A Systm of Computer Integration of Patient Monitors in Operating Rooms

As one of the major subsystems of our new THE OPERATION SUPPORTING INFORMATION SYSTEM IN THE SURGICAL CENTER, we have developed a system which integrates patient monitors in operating rooms.

Emergency Medical Service System (EMSS) in Tokyo: Special Reference to the Disaster Program

The Emergency Medical Service System in Tokyo has been developed through the cooperative efforts and achievements of many. EMS in Tokyo consists of three parts: 1) the network system of emergency hospitals; 2) the transportation system of emergency patients (Ambulance System); and 3) the communications system (Emergency Medical Information System). Emergency services are controlled by the Japanese Ministry of Home Affairs and the Ministry of Health and Welfare. The former is in charge of ambulance and rescue services located in the fire department, the latter has to do with medical affairs.