Segmentation of organs of sight such as the eyeballs, lenses, and optic nerves is a time consuming task for clinicians. The small size of the organs and the similar density of the surrounding tissues make the segmentation difficult. We developed a new algorithm to segment these organs with minimal user interaction. The algorithm needs only three seed points to fit an initial geometrical model to start an effective segmentation. The clinical evaluation shows that the output of our method is useful in clinical practice.

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We developed a new radioisotope technique to measure placental blood flow for the early detection of placental insufficiency. Using the parametric scan, placental perfusion was measured in 80 late-pregnant women. The T-maximum pictures obtained made it possible to differentiate between the vascular and intervillous phases of placental blood flow. The time period of intervillous phase calculated as the percentage of the whole placental Tmax was given as the intervillous perfusion index (IPI). It was demonstrated that the IPI was significantly higher in pregnancies complicated with intrauterine growth retardation (64.2% +/- 16.5%), hypertension (60.0 +/- 15.2) and oedema (57.9% +/- 10.1%) than in the control group (33.7% +/- 10.5%). These data suggest that the first sign of placental insufficiency is the prolongation of the IPI which is likely to precede the quantitative reduction of placental perfusion.

A software system (MicroSegams) is described w h c h is able to acquire, store, present, and process nuclear medicine images. The most important basic procedures (e.g., image acquisition from a gamma camera, selection of a study from the catalogue, drawing regions of interest, etc.) and complete clinical procedures (e.g., renography, brain perfusion, etc.) can be activated directly from the system menu by mouse. The language sLan (a subset of programming language c containing more than 200 elementary functions) can also be used to write new procedures to be interpreted or compiled. The system is offered as a basic tool for the performance of static, dynamic, gated, or tomographic investigations in clinical practice. NUCLEAR MEDICINE DATA-PROCESSINGDuring nuclear medicine studies, a radioactive material, called a radiopharmaceutical, is administered into the patient. This takes part in the physiological processes, e.g., it is accumulated in the liver or it is distributed in the blood. Through detection of the radioactivity, interesting biological functions become "visible." Their images are the basis of the medical reports made by the physicians who utilize nuclear medicine.This kind of imaging technique needs a radioactive material, a special imaging device, and an image processing system. The radiopharmaceutical is prepared by binding a radioactive element to a special chemical which takes part in the process to be imaged. For example, HMPAO labelled with the isotope 99m-Tc is suitable for demonstrating the regional cerebral blood flow distribution in the brain [l], or 201-TI can be used to image the myocardium. The applied imaging devices are able to detect the emitted photons in an image of circular or rectangular form (ca. 25-70 cm in diameter). The images are recorded on film or stored on magnetic disks after analog-todigital conversion. In many cases, the physician has to carry out sophisticated procedures on the acquired images in order to obtain the necessary information (e.g., to compute certain parameters, curves, or new images). To do this, complete hardwareisoftware data processing units are used which are capable of the acquisition, processing, and archiving of study data (for a survey see, e.g., Ref. 2).Our system (MicroSegams) is a nuclear medicine data acquisition and image processing system for performing procedures on images taken by gamma cameras. The philosophy of the system is to divide the tasks into three groups according to their frequency: The first group contains the most frequently Received 27 December 1990; revised manuscript received 14 May 1991 used complete clinical programs, the steps of the processing being performed in a prescribed sequence almost fully automatically. The second group consists of tasks that can be carried out by the elementary steps offered by the menu of the system (e.g., the selection of a file from the catalogue, or the saving of the contents of the actual screen). Finally, for very special problems the user can write his own programs with or without t...

In this paper, we present a new mathematical method that synthesizes normal data sets for quantification of regional myocardium perfusion. In clinical practice, regional myocardial perfusion is often measured with a gamma camera and quantified via circumferential profile analysis. Normal reference profile data is used to increase the accuracy of the clinical interpretations. Our goal is to create reference data from an existing set of archived studies. An iterative mathematical method, based on two statistical hypotheses, was used to generate the study set instead of collecting normal examinations from a healthy population. Clinical validation is based on interpretations by six independent observers. Results of evaluation with synthesized normal data and its validation are presented.