John L. Floyd

Single injection thallium-201 stress and redistribution myocardial perfusion imaging: comparison with stress electrocardiography and coronary arteriography.

The efficacy of single injection thallium-201 exercise stress and rest redistribution imaging in the evaluation of myocardiacl ischemia was compared with stress electrocardiography and coronary arteriography. Thallium-201 imaging was interpreted at two levels of sensitivity in order to define the circumstances under which it best serves as a screening modality for coronary arteriography. With the prevalence of coronary disease usually found in patients referred for coronary arteriography (75%), unprocessed thallium-201 imaging is as good as stress electrocardiography in identifying patients apt to show coronary artery abnormalities, but not much better than stress electrocardiography in delineating those patients unlikely to show coronary artery disease. In contrast, processed lesion enhanced images showing normal results virtually eliminate the possibility of significant arteriographic findings. With this screening technique, many patients may be spared unnecessary coronary arteriography.

Bone scintigraphy in the diagnosis of mastoiditis

Bone scintigraphy has proven utility in the early diagnosis of osteomyelitis, but the authors were unable to find any report of its specific application to mastoiditis. Three cases of mastoiditis are presented in which the bone scan findings predicted the histopathologic findings.

A simplified method for the routine determination of effective renal plasma flow.

Quantitative renal data (i.e., glomerular filtration rate or effective renal plasma flow) often would be useful ancillary information when radionuclide renography is carried out. The added time, and therefore cost, of obtaining quantitative information might be the main reason a department does not routinely perform a quantitative study, although there is no added radiation or risk to the patient. To simplify the procedure for determining effective renal plasma flow with I-123 orthoiodohippurate (OIH), the published methodology was modified to eliminate the repetitive preparation of a standard solution. This allows the routine incision of effective renal plasma flow (ERPF) determination in I-123 OIH renography with minimal impact on departmental operations.

Hepatic imaging: a comparison of Tc-99m-sulfur colloid and PIPIDA in the detection of defects.

A prospective investigation comparing Tc-99m-PIPIDA with Tc-99m-sulfur colloid in the detection of defects of the liver was carried out in 30 volunteers. By acquiring images of 1 million counts from 5-10 minutes postinjection, high quality hepatic images could be obtained with PIPIDA. Separate interpretations by three nuclear physicians yielded similar results between paired PIPIDA and sulfur colloid studies (KAV = 0.95 ± .09, P <0.001). Early multiview imaging of the liver in the course of hepatobiliary evaluation with PIPIDA may yield valuable information relative to the presence of lesions.

Hemobilia: An unusual cause of segmental bile duct obstruction

Hemobilia is reported as an unusual cause of segmental bile duct obstruction. The finding of focal “hot spots” caused by delayed washout of the tracer from the obstructed segments is discussed. Whenever the clinical triad of pain, intermittent jaundice, and gastrointestinal bleeding is associated with the above findings, the diagnosis of hemobilia should be entertained.

Probe radiocardiography: validation of a technique to routinely determine left ventricular ejection fraction.

We investigated the probability of obtaining a valid radiocardiogram with the first commercially available cardiac probe and a peripheral injection of the radiopharmaceutical. Measurements of left ventricular ejection fraction (LVEF) were obtained in a series of 15 patients undergoing cardiac catheterization. Probe LVEF determinations using central, peripheral and rapid sequential injections correlated well with each other and with ventriculography (r = .88-.98). By documenting its accuracy and precision, this study confirms the validity of a new technique for measuring LVEF.