[First pass radionuclide angiography in the measurement of the left ventricular ejection fraction--assessment of the accuracy of a new method]

This study was designed to validate a modified computer program in evaluating the left ventricular ejection fraction (LVEF) by first pass radionuclide cardioangiography. This program was modified by us from the pulmonary background subtraction method postulated by Gal et al. Another three programs supplied by the computer company were included in the study to compare the accuracy among these program algorithms. From the results of 97 patients undergoing first pass and gated equilibrium cardiac blood pool studies, we found that the measured ejection fractions by these four programs were all correlated well with those by the equilibrium gated cardiac program (r = 0.81-0.86). The latter was already confirmed and verified in a previously published work using a Vanderbilt dynamic cardiac phantom. Except for the LVEF values obtained from our modified program, all values obtained from the other three programs were significantly lower than those obtained by the verified equilibrium program. However, the results obtained from our designed program correlated well with those obtained from the equilibrium method. Furthermore, none of the patient's raw data was rejected by this modified program.

Quality assurance and precision of dual photon absorptiometry in bone mineral measurement

Dual photon absorptiometry (DPA) has evolved as a powerful technique in measuring bone mineral density (BMD) to assess osteoporosis and metabolic bone diseases in recent years. We introduced the first installation of DPA instrument into this country in Aug. 1987. Since the comparison among longitudinal BMD values influences the diagnosis, monitoring and medical decision-making, high precision of the system performance and strict quality assurance program are prerequisite for judgment of the difference between two successive measurements. However, the automation and black-box software design of the instrument make users gain very little knowledge how the instruments acquire the long-term system reliability. The first part of this study was designed to establish a standardized procedure to evaluate the long-term quality of the DPA instrument. Our instrument was proved to have stable sensitivity, resolution, accuracy and reproducibility in the four months of study. Three subjects with different BMD levels were scanned to evaluate the intraobserver and interobserver errors in BMD analysis expected in our laboratory (2.2 and 1.6% at 95% confidence level, respectively). The results indicated that reanalyzing the same scan by either of the two observers would produce a BMD precision error within 2.2% at a 95% confidence level. Serial scans of 7 normal volunteers within five weeks were then conducted to evaluate the overall precision of the BMD measurements. Our findings indicated that two scans would be considered as having a real BMD change if they differ by more than 3.3% at a 95% confidence level. There are at least five sets of DPA instruments that have been installed in Taiwan presently.(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of nonvisualization of extrahepatic bile duct in intravenous radionuclide cholescintigraphy with special reference to acute suppurative cholangitis

Intravenous radionuclide cholescintigraphy using Tc-99m HIDA was performed in 386 consecutive patients with suspected biliary disease. Among 365 patients with prompt hepatic uptake, the common bile duct was not visualized in 19 (5.2%). Biliary calculi with infection, especially suppurative cholangitis, is the most frequent condition responsible for this cholescintigraphic pattern. Conditions involving the common bile duct from extrinsic causes may also present this pattern. This pattern is a specific indicator of pathology in the common bile duct. In addition, it is diagnostic for acute suppurative cholangitis, with a sensitivity of 66.7%, a specificity of 90.5%, an accuracy of 88.3%, a positive predictive value of 42%, and a negative predictive value of 96.3%. Aside from mechanical obstructions, functional obstruction of a normal sized common duct that contained no calculi could also be detected by this pattern.

Role of iron-binding proteins and enhanced capillary permeability on the accumulation of gallium-67

We studied the role of the iron-binding proteins transferrin and lactoferrin and of increased capillary permeability on the accumulation of gallium-67 in rabbits. Intramuscular injection of histamine caused accumulation of gallium-67 (injected i.v. as citrate), and of Tc-99m DTPA, at the i.m. injection site. Normal saline and albumin did not. Intramuscular injection of transferrin or lactoferrin similarly caused Ga-67 uptake. No accumulation of Tc-99m DTPA was observed at the site of transferrin injection but there was a slight accumulation at the site of lactoferrin injection. Prior saturation of transferrin or lactoferrin with ferric ion abolished their effect on Ga-67 accumulation. Gallium-67, pre-bound to transferrin vitro, did not accumulate at the site of histamine or transferrin injection, but there was a slight accumulation at the lactoferrin site. Our results suggest that either increased capillary permeability or iron-binding progeins can cause local uptake of Ga-67. Since these factors are present at sites of inflammation, they may contribute to the accumulation of gallium in inflammatory lesions.