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Previous reports have suggested that left ventricular ejection fraction can be assessed by recording the passage of peripherally administered radioactive bolus through the heart. The accuracy and validity of this technique were examined in 20 patients undergoing diagnostic cardiac catheterization. 99m-Tc-human serum albumin was injected via a central venous catheter into the superior vena cava and precordial activity recorded with a gamma scintillation camera interfaced to a small digital computer. A computer program was designed to generate time-activity curves from the left ventricular blood pool and to calculate left ventricular ejection fractions from the cyclic fluctuations of the left ventricular time-activity curve which correspond to left ventricular volume changes during each cardiac cycle. The results correlated well with those obtained by biplane cineangiocardiography (r equals 0.94) and indicated that the technique should allow accurate and reproducible determination of left ventricular ejection fraction. The findings, however, demonstrated that the time-activity curve must be generated from a region-of-interest which fits the left ventricular blood pool precisely and must be corrected for contributions arising from noncardiac background structures. This nontraumatic and potentially noninvasive technique appears particularly useful for serial evaluation of the acutely ill patient and for follow-up studies in nonhospitalized patients.

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The quasifree scattering process (QFS) has been studied in the reaction D(P, 2P)n at incident energies of 14, 17, 20, 28, 88, 38, 45, and 57 MeV at 0I =OR --43' (left and right) to the incident beam and PLR --180'. The QFS peak cross section remains almost constant from 20 to 100 MeV and begins to drop at lower energies. The magnitude of the cross section, as well as the shape of the QFS peak, is compared with predictions of a modified-simple-impulse-approximation calculation including a cutoff radius. The energy dependence of the QFS peak cross section is compared with the corresponding cross sections of the reaction D(P,Pn)P and to the free nucleon-nucleon elastic scattering cross sections.