Computer graphics for digitally formatted images

The increasing use of digitally formatted imaging systems requires high-quality interactive gray-scale computer raster graphics systems for the management, display, and analog film recording of digital image and alphanumeric information. These systems are a combination of computer hardware and software and implement a set of graphics protocols. This paper describes a set of interactive graphics protocols that has been developed for clinical use.     

Failure of ablation of a mediastinal parathyroid adenoma by repeated contrast staining

In a patient with primary hyperparathyroidism an attempt was made to ablate a middle mediastinal parathyroid gland by forceful staining with radiographic contrast material. The gland was stained on two separate occasions, two weeks apart. Both times the serum calcium level temporarily fell to the normal range but reverted to abnormal levels. The patient ultimately required surgery for correction of hypercalcemia. The mechanism of staining and possible reasons for failure as well as potential complications are discussed.     

Gallium-67 lung uptake: conjugate-view technique

A conjugate-view technique is derived for calculation of absolute gallium-67 (Ga-67) uptake from scintillation-camera images. The technique combines counts of posterior and anterior images of the lung with an attenuation correction obtained from cobalt-57 (Co-57) transmission imaging. The formulation is such that the effects of Compton scatter build-up are accounted for. Studies utilizing a canine model indicated that, normally, more activity is located in the chest wall than in the lungs. The quantitative technique must therefore accurately account for a variety of Ga-67 distributions, including that in the chest wall. Calculations were performed using a three-component model comparing results obtained with the conjugate-view approach to the actual uptake. These calculations suggest that an assumption of uniform activity distribution allows an accuracy of approximately +/- 10% over a broad range of body-part thicknesses and uptake by the lungs. It was concluded that the conjugate-view technique is necessarily approximate but can provide clinically useful results.     

Building geographic information system capacity in local health departments: lessons from a North Carolina project

State government, university, and local health department (LHD) partners collaborated to build the geographic information system (GIS) capacity of 5 LHDs in North Carolina. Project elements included procuring hardware and software, conducting individualized and group training, developing data layers, guiding the project development process, coordinating participation in technical conferences, providing ongoing project consultation, and evaluating project milestones. The project provided health department personnel with the skills and resources required to use sophisticated information management systems, particularly those that address spatial dimensions of public health practice. This capacity-building project helped LHDs incorporate GIS technology into daily operations, resulting in improved time and cost efficiency. Keys to success included (1) methods training rooted in problems specific to the LHD, (2) required project identification by LHD staff with associated timelines for development, (3) ongoing technical support as staff returned to home offices after training, (4) subgrants to LHDs to ease hardware and software resource constraints, (5) networks of relationships among LHDs and other professional GIS users, and (6) senior LHD leadership who supported the professional development activities being undertaken by staff.     

Platelet Functions in Cardiopulmonary Bypass Surgery

Background

Haemorrhage after Cardio Pulmonary Bypass (CPB) Surgery is a well recognised complication that leads to significant morbidity and mortality. The incidence varies between 5-25% depending upon the clinical situation. Several factors are implicated as causative but none have been precisely proved.

Methods

Our study was an attempt to evaluate the haemostatic defect with particular reference to platelet function abnormalities during cardio pulmonary bypass surgery, in order to reduce the morbidity and mortality associated with post CPB haemorrhage. Flow cytometric evaluation of different platelet glycoproteins like GPIb/IX, GPIIb/IIIa and GMP-140 was done.

Results

The marker expression showed deregulation during surgery which returned to base after bypass was terminated. In contrast, the cases with bleeding showed significant variation. P-Selectin (GMP 140) expression decreased progressively till 3^rd post-operative day showing lack of activation of platelets in cases of severe bleeding.

Conclusion

Longer duration of CPB initiates plasmin generation through heparin, which raises the PAI-1-tPA complex and thereby down regulating the functions of platelets. This suggests a link between duration of CPB, bleeding, platelet dysfunction and fibrinolysis. Hence serial estimations of the levels of GMP-140 and tPA can predict severe bleeding.Key Words: CardioPulmonary Bypass, Platelet dysfunction, flowcytometry, platelet glycoproteins, haemorrhage     

Renal pelvis volume during diuresis in children with hydronephrosis: implications for diagnosing obstruction with diuretic renography

PURPOSE: We measured the volume of the renal pelvis during diuretic renography (DR) in children with normal and hydronephrotic kidneys to determine if changes in pelvic volume could affect the accuracy of DR in diagnosing obstruction. MATERIALS AND METHODS: We studied 18 patients 1 month to 10 years old with unilateral hydronephrosis ultimately proved to be either obstructive or nonobstructive. Simultaneous DR and ultrasound were performed with patients supine using the gamma camera. Ultrasound measurements of the renal pelvis in 3 dimensions, obtained before and at intervals after diuretic injection, were used to calculate renal pelvic volume. The contralateral normal kidneys were used as controls. RESULTS: Between 15 and 60 minutes after diuretic injection the renal pelvis enlarged to a maximum volume in all hydronephrotic and normal kidneys and then gradually decreased in size. Mean average increase in volume for hydronephrotic kidneys ranged from 46% in obstructed kidneys to 88% in nonobstructed kidneys. Volume expansion caused dilution of isotope within the renal pelvis, which resulted in prolongation of elimination half-time (T1/2) in 42% of nonobstructed hydronephrotic kidneys sufficient to register an obstructed washout pattern. However, there were no differences in the initial pelvic volume or the rate or extent of increases or decreases in pelvic volume that would permit nonobstructed hydronephrotic kidneys to be distinguished from obstructed ones. CONCLUSIONS: The renal pelvis enlarges during diuresis in children with hydronephrosis. This enlargement causes dilution of isotope within the renal pelvis during DR, which prolonged the isotope washout rate or T1/2 sufficiently to produce an obstructed washout pattern in more than 40% of hydronephrotic kidneys that were ultimately proved to be nonobstructed. This misdiagnosis of obstruction is particularly likely to occur in children younger than 2 years because pelvic volume expansion is so exaggerated. Consequently, T1/2 appears to be particularly vulnerable to inaccuracy in diagnosing obstruction in this age group, and, therefore, it should not be relied on as an operative determinant.