In vivo assessment of 111In-labeled hematoporphyrin derivative in breast tumor-bearing animals.

The biological behavior of 111In-labeled HPD has been investigated in tumor-bearing animals. Mice mammary adenocarcinomas and 7,12-dimethylbenz(a)anthracine induced breast tumors in Sprague-Dawley female rats were clearly visualized by 111In-HPD nuclear scintigraphy. Optimal scans were obtained after a 48 h delay. In normal and tumor-bearing animals, the highest uptake of 111In-HPD 72 h post-injection was found in the liver, the spleen and the kidneys. Depending on the size and the extent of necrosis, the uptake of 111In-HPD by malignant breast tumors varied from 2.5% injected dose (ID) (range 0.14-5.3% ID) in mice to 1% (range 0.22-8.1% ID) in rats. Benign breast tumor uptake of 111In-HPD was less than 1% ID. No significant amount of the radiopharmaceutical was found in pulmonary abscesses and abdominal cysts (less than 0.1% ID). Scintigrams of these infectious or inflammatory lesions were normal. Malignant tumor to blood, heart and lung ratios averaged 50:1, 10:1 and 3:1 respectively. Tumor to brain ratio ranged from 72 to 444:1.

Albumin lung/heart ratio change. A simple clinical means of documenting increased pulmonary endothelial permeability to protein.

We investigated a simple method that can be used at the bedside for documenting the net accumulation of albumin in the lung. The technique employs measurement with a computer-linked gamma camera of the activity ratio in an area of the right lung compared with the same-sized area in the heart at 20 minutes and three hours following intravenous injection of technetium Tc 99m albumin. We applied this measurement to three groups of patients: a control group and patients with roentgenographic evidence of edema classified according to clinically available criteria as either hydrostatic edema or permeability edema to see if we could document differences among these groups. In control patients this ratio did not increase by more than seven units between the 20-minute and three-hour measurements. Of 18 patients classified by other routine clinical means as having hydrostatic pulmonary edema, 89% showed no increase in lung albumin accumulation. In 29 patients with permeability edema associated with the so-called adult respiratory distress syndrome, 31% showed evidence of net pulmonary albumin accumulation. These findings suggest that some patients otherwise classified as having hydrostatic edema have concomitant permeability changes in the microvasculature and that permeability edema represents a spectrum of endothelial damage.

In vivo assessment of 99mTc-labeled hematoporphyrin derivative in tumor-bearing animals.

The efficacy of 99mTc-labeled hematoporphyrin derivative in localizing neoplasms has been investigated with tumor-bearing animal models. Spontaneous mammary adenocarcinomas of outbred CFW strain Swiss-Webster white mice and chemical carcinogen induced breast tumors in female Sprague-Dawley white rats were clearly visualized in the scintigrams. Mice tissue distribution data demonstrate favourable tumor to organ ratios sufficiently high to permit tumor detection. [99mTc]HPD appears promising as a tumor imaging agent.

Imaging endocarditis with Tc-99m-labeled antibody--an experimental study: concise communication.

The sensitivity and specificity of Tc-99m-labeled antibacterial antibody (Tc-99m Ab) for detecting bacterial endocarditis were evaluated in an experimental model. Rabbit-produced antistaphylococcal antibody was extracted using Rivanol and chemically labeled with Tc-99m. This Tc-99m Ab was injected intravenously in New Zealand rabbits 24 hr after producing Staphylococcus aureus endocarditis of the aortic valve. Imaging and tissue analyses were performed on the following day. All 11 animals developed S. aureus aortic-valve vegetations and showed increased uptake of Tc-99m Ab at the aortic valve, 118 times higher than at the uninfected tricuspid valve. Although high hepatic radioactivity and anatomic uncertainties interfered with in vivo delineation of these lesions, images of the excised hearts showed all affected valves. Two rabbits inoculated with Escherichia coli did not develop endocarditis and had little uptake of Tc-99m Ab, while six rabbits with enterococcal endocarditis had no uptake of the Tc-99m Ab in their vegetations. The findings suggest potential value of Tc-99m Ab on the rapid diagnosis of endocarditis.

Direct recording on rectilinear scan images on 4x5-in. film.

Rectilinear scans are usually recorded on 14 X 17-in. x-ray film. This is costly both in terms of film and storage space. Using 4 X 5-in. film instead of the larger film will reduce this cost. An Ohio-Nuclear Model 84FD dual-probe 5-in. scanner was converted for the production of scan images directly on 4 X 5-in film (Kodak SO-79 nuclear medicine film). The smaller images may be viewed directly on a standard x-ray viewbox, or they may be projected if a larger image is desired. The image quality is excellent. This system has replaced the 14 X 17-in. film at our institution.

Technique for producing cardiac radionuclide motion images.

Sequential frames of different portions of the cardiac cycle are gated into a minicomputer by using an EKG signal recorded onto digital tape simultaneously with imaging information. Serial display of these frames on the computer oscilloscope or projection of 35-mm half frames of these images provides a cardiac motion image with information content adequate for qualitatively assessing cardiac motion.