Acute pulmonary embolus associated with transient ventilatory defect: Case report.

In a patient with a clinical history highly suggestive of pulmonary embolism and angiographic evidence also indicative of embolism, the ventilation/perfusion pattern was that usually observed with parenchymal disease of the lung. The possible basis of this contradiction is discussed.

The effect of iatrogenic trauma on the bone scintigram: an animal study: concise communication.

An animal study was performed to assess the effect on the Tc-99m phosphate bone scintigram of injury by needle aspiration or drill hole to metaphyseal and diaphyseal areas in immature and mature bones. Results showed that in 12 immature rabbits such trauma to metaphyseal regions had no effect on the bone image. Similar metaphyseal trauma in two mature dogs showed definite abnormalities on the bone image, but in one mature rabbit, no abnormality could be identified by scintigram. Diaphyseal trauma always gave a definitely abnormal bone image. Extrapolation of these results to humans should be cautious, but it suggests that needling or drilling in metaphyseal regions in neonates or young children probably does not affect later bone images.

Scintigraphic detection of intrapulmonary bleeding using technetium-99m sulfur colloid: concise communication.

Radionuclide imaging has been successfully used clinically to determine sites of gastrointestinal hemorrhage, but its use in hemoptysis has not been studied. A dog model of intrapulmonary hemorrhage was devised. Utilizing technetium sulfur colloid, at doses of 4 and 15 mCi, bleeding rates of 0.1--0.2 cc/min were detected. In some dogs, however, significantly higher bleeding into a large bronchus, which causes a diffuse distribution of the radionuclide.

Tissue distribution of 203 Pb-acetate: comparison with 67 Ga-citrate as an abscess-localizing agent.

Since 203Pb-acetate accumulates in necrotic tumor tissue, the possibility was raised that it might also accumulate in other necrotic tissue such as abscess. We first studied the tissue distribution and excretion of 203Pb-acetate in control rats at 4, 24, 48, 72, and 96 hr. An enterohepatic circulation for lead is suggested. We then compared the uptakes of 203Pb-acetate and 67Ga-citrate in experimental abscesses in rats. The mean gallium accumulation in the abscess was 10 times that of lead at 24 hr and 12 times that of lead at 72 hr. The abscess-to-tissue ratios were greater for gallium for every tissue examined, although the abscessed areas were clearly visualized by scanning at 24 and 72 hr with both agents. With the exception of blood, abscess-to-tissue ratios for 67Ga at 24 hr were higher than or equal to those at 72 hr. However, the 67Ga ratios for the inflamed tissue surrounding the abscess to muscle and blood were higher at 72 hr than at 24 hr, which suggests that inflammation without abscess might be better identified by gallium scanning at 72 hr.

Intestinal concentration of 99mTc-pertechnetate into isolated loops of rat bowel.

In scanning patients for Meckel's diverticulum, the colon occasionally visualizes more rapidly than would be expected simply from gastric secretion and intestinal transit. To gain a better understanding of the intestinal physiology of pertechnetate and thereby to make a more intelligent interpretation of abdominal scans, segments of the gastrointestinal tract of Sprague-Dawley rats were isolated by transection between double ligations. After abdominal closure, the animals received an intravenous injection of 99mTcO4 and were killed at 30, 45, or 150 min after injection. Technetium concentrations in the stomach, colon, and appendiceal contents increased significantly with time after dosing, and after 30 min technetium could be clearly imaged in the stomach, upper small intestine, appendix, and colon. These results suggest that technetium is actively secreted by the intestinal mucosa. Additionally, the results indicate caution in the interpretation of scans in patients with suspected Meckel's diverticulum since, in the rat and probably in the human, significant amounts of technetium can accumulate in the gut apart from gastric secretion and intestinal transit.

Peritoneal fluid causing inferior attenuation on SPECT thallium-201 myocardial imaging in women.

On SPECT thallium images, myocardial left ventricular (LV) anterior wall attenuation due to breast tissue is common in women. In contrast, in men, inferior wall counts are normally decreased compared to anterior counts. The purpose of this report is to describe cases of inferior wall attenuation of counts in women caused by peritoneal fluid, not myocardial disease. Twelve consecutive SPECT thallium myocardial studies performed in women on peritoneal dialysis, being evaluated for kidney transplant, were included in this study. For all studies, 3.5 mCi 201Tl were injected intravenously. Thirty-two images were acquired over 180 degrees (45 degrees RAO progressing to 45 degrees LPO) at 40 sec per stop. SPECT images were reviewed in short axis, horizontal long and vertical long axes. Data were also displayed in "bullseye" format with quantitative comparison to gender-matched normal files. Ten of 12 female patients studied had inferior wall defects on images, confirmed by bullseye display. All patients had approximately 2 liters of peritoneal fluid. Review of planar rotational views showed diaphragm elevation and fluid margin attenuations affecting left ventricular inferior wall. Thus, peritoneal fluid is a cause of inferior attenuation on 201Tl cardiac imaging.

Advantage of indium-111 leukocytes over ultrasound in imaging an infected renal cyst.

Indium-111-labeled leukocyte scanning is a highly sensitive and specific method of detecting abscesses. This report describes a patient with polycystic kidneys and a single infected cyst. Ultrasound could not determine which cyst was infected, but the infected cyst could be localized by [111In]leukocyte imaging in conjunction with a [99mTc]DMSA renal scan. The two radionuclide studies were used to identify an infected renal cyst and direct ultrasound guided aspiration.

Distribution of 67-Ga following intravenous administration: effects of disodium edetate therapy.

Following intravenous administration of 67Ga-citrate to normal and abscessed rats, the colon content of 67Ga decreased with increasing oral doses of Na2EDTA. The effects observed, however, were not thought to be of potential clinical value.

A rapid method for the labeling of albumin microspheres with In-113 and In-111: concise communication.

A rapid and simple method for preparing microspheres labeled with In-113m or In-111 is described. The procedure requires 10 min and gives labeling yields approaching 100%. Biodistribution studies in rats, mice, and dogs show the product to be biologically stable, with approximately 90% of the injected dose localized in the lung at 1 hr postinjection. The convenient production of In-113m or In-111 albumin microspheres provides an alternate radiopharmaceutical to complement or substitute for Tc-99m microspheres in lung perfusion imaging and other circulation studies.

Monitoring of I-125 contamination using a portable scintillation camera.

A technique has been developed using a portable scintillation camera to monitor I-125 contamination of personnel. The procedure takes less than a minute to complete and can detect 3 nanocuries; its use minimizes dissemination of I-125 throughout the hospital, emphasizes safe iodination practices and proper handling of radioactive materials, and reduces radiation exposure by undetected contamination.

Gastric emptying measurements: delayed and complex emptying patterns without appropriate correction.

Anteriorly acquired and geometric mean corrected gastric emptying curves of solids and liquid isotopic-labeled meals were compared in 37 subjects given 61 meals of three different sizes. Anterior data alone consistently and significantly underestimated solid-phase gastric emptying rates with all meal sizes when compared to geometric mean acquired data. However, with liquids there were only slight differences between anterior and anterior and posterior geometric mean corrected emptying-rates. The difference probably reflects greater attenuation of the 140 kev photon of 99mTc compared to the 247 keV photon of 111In. With anterior data alone, an apparent early delay in emptying of solids was present with all meal sizes and the resultant emptying curves were nonlinear in shape. Geometric mean correction resulted in the linearization of the solid-phase emptying curves and essentially eliminated the apparent delay in emptying or lag phase noted with the anterior data alone. Based on our results, geometric mean correction techniques are necessary for accurate assessment of radioisotopic-labeled solid meals.

SPECT thallium-201 scintigraphy for the detection of left-ventricular aneurysm.

We have noted that the presence of left ventricular anterior/apical aneurysm on contrast ventriculography or echocardiography correlates well with the finding of failure of convergence of the left ventricular walls toward the apex on single photon emission computed tomography (SPECT) thallium-201 images. To assess this observation, we analyzed the SPECT thallium scans of 74 sequential patients who had SPECT thallium scintigraphy and contrast ventriculography and/or echocardiography for evaluation of coronary artery disease. Immediate post-stress and 4-hr redistribution thallium-201 SPECT images, obtained following i.v. administration of 2 mCi of thallium-201, were reconstructed with no attenuation correction using three-dimensional linear and nonlinear filters and displayed in short, vertical-long, and horizontal-long axes. Of the 74 patients, contrast ventriculography and/or echocardiography showed anterior/apical aneurysms in 15 and a posterolateral aneurysm in one. SPECT thallium scans detected 14 of the 16 aneurysms, based on the criterion of failure of convergence of the ventricular walls toward the apex. There were two false-positives. Thus SPECT thallium-201 scintigraphy for the detection of left-ventricular aneurysm in this series had a sensitivity of 94%, a specificity of 97%, and an accuracy of 96%.

Assessment of skin ulcer healing capability by technetium-99m phosphate angiogram and blood-pool images.

The accuracy of radionuclide angiography and blood-pool imaging using [99mTc]-phosphate to assess skin ulcer perfusion as an indicator of healing capacity was determined in 50 studies performed on 45 patients with nonhealing ulcers of the lower extremities. Two nuclear medicine physicians without clinical bias, graded the perfusion of the ulcer on the images as normal, increased or reduced with respect to the opposite limb. Patients were followed closely with aggressive local wound care for at least 14 days. Of the 31 ulcers which healed, the radionuclide study correctly predicted 30; of the 19 ulcers which did not heal, 14 were correctly predicted. Eight patients had osteomyelitis; four of those healed and four did not. The radionuclide study predicted healing in seven. Excluding those patients with osteomyelitis, the sensitivity for the radionuclide angiogram and blood-pool image in predicting healing was 96%, specificity was 87%, and accuracy was 93%. This technique is a simple, reliable way to predict the microcirculatory adequacy for ulcer healing. Specificity is diminished in the presence of osteomyelitis.

Decreased sensitivity of early imaging with In-111 oxine-labeled leukocytes in detection of occult infection: concise communication.

Imaging with leukocytes labeled with indium-111 oxine is a sensitive technique for detecting sites of occult infection. Traditionally, imaging is performed 24 hr after injection. We undertook a prospective study of 35 patients (40 studies) with possible occult infection to see whether a 24-hr delay in imaging is really necessary. Patients were imaged at 1-4 hr and again at 24 hr after injection. The early images had a sensitivity of only 33%, compared with 95% for the 24-hr images. Of the seven studies that were positive on both early and delayed images, 71% had more intense uptake at 24 hr. There were no false-positive early images. We conclude that imaging 1-4 hr after injection with In-111 oxine-labeled leukocytes has a low sensitivity for detecting occult infection. However, a positive early image is specific for a site of infection.

Tumor model studies of 131I-tetracycline and other compounds.

Iodine-131-tetracycline (131I-TET) was prepared by allowing tetracycline hydrochloride to react with radioiodide in acidic methanol (labeling efficiency greater than 85%). This preparation was found to be stable at--4 degrees C for at least 72 hr. Some minimal in vivo breakdown did occur. The 131I-TET, 67Ga, and several 99mTc compounds were studied in a rat hepatoma model. The incorporation of the radiopharmaceuticals into the tumor occurred rapidly, with peak levels at 0.5 and 24 hr after injection for 131I-TET and 67Ga, respectively. The clearnace of the radiopharmaceutical from nonviable tumor was slower than for viable tumor, and by 72 hr after injection the greatest concentration of radioactivity appeared in the nonviable fraction. All normal tissues showed faster clearance than did tumor tissue, regardless of viability. Decreasing the quantity of 131I-TET injected increased the percent of uptake in the nonviable tumor tissue but had no effect on the viable tumor uptake. Of the 99mTc compounds studied, the phosphates developed the highest tumor-to-background ratios. Unfortunately these ratios were not as high as those achieved for 67Ga or 131I-TET.

Value of a 24-hour image (four-phase bone scan) in assessing osteomyelitis in patients with peripheral vascular disease.

The delayed images of the four-phase 99mTc phosphonate bone scan are compared with the delayed images of the three-phase study in patients with diabetes mellitus and/or peripheral vascular disease and suspected osteomyelitis. Three-phase bone imaging includes an immediate postinjection radionuclide angiogram, a blood-pool image, and delayed static images to 7 hr. The four-phase study adds a 24-hr static image. The scan is positive for osteomyelitis if images show progressively increasing lesion to background activity ratios over time. The results of analyzing 21 three- and four-phase bone scans in 17 patients were correlated with clinical course, cultures, and/or x-rays, gallium scans, and CT scans. The accuracy of four-phase bone imaging for diagnosing osteomyelitis was 85%; for three phase, 80%. Sensitivity for four phase was 80%; specificity was 87%. Sensitivity for three phase was 100%; specificity was 73%. Since overall accuracy of the four-phase study is slightly better than three phase, in these patients with diabetes mellitus and/or peripheral vascular disease, the addition of a 24-hr image, creating a four-phase bone scan, is recommended.

No difference in sensitivity for occult infection between tropolone- and oxine-labeled indium-111 leukocytes.

There is considerable disagreement as to whether oxine or tropolone is the best labeling agent for indium leukocytes. We have previously looked at the sensitivity of oxine-labeled 111In leukocyte scans for occult infections and now present a similar group of patients imaged with tropolone-labeled 111In leukocytes. Thirty-four patients (38 studies) with possible occult infection were prospectively studied. Patients were imaged 1-4 hr after injection and again at 24 hr postinjection. The early tropolone images had a sensitivity of 53% while the delayed images at 24 hr had a sensitivity of 93%. Based on a previous study, oxine-labeled leukocyte scans have an early sensitivity of 33% and a delayed sensitivity (at 24 hr) of 95%. The differences in sensitivity between oxine and tropolone when imaged early and at 24 hr were not statistically significant. We conclude that there is no significant difference in the ability to detect infection between oxine- and tropolone-labeled leukocytes, both early at 1-4 hr, and on delayed imaging 24 hr after injection.

Radioimmunodetection of human melanoma with indium-111-labeled monoclonal antibody.

The purpose of the study was threefold: (1) to evaluate the efficacy of an 111In-labeled murine monoclonal antibody (ZME-018) directed against a heavy molecular weight melanoma associated glycoprotein in localizing metastatic disease; (2) to determine the effect of unlabeled antibody mass (2.5, 5, 10, 20, and 40 mg) on labeled antibody blood clearance, biodistribution and lesion detection; (3) to estimate radiation dosimetry. Twenty-five patients with previously documented disease received an intravenous infusion of 2.5 to 40 mg of monoclonal antibody with 1 mg of the antibody labeled with 5 mCi of 111In. There were no acute reactions. Patients were scanned without computer enhancement or background subtraction techniques at 24 and 72 hr after injection. Imaging detected tumor in 14/18 (78%) patients with active disease, identified 24/44 (77%) of lesions greater than 1 cm and changed or specifically directed patient management in 22% (4/18) patients with tumor. There was a prolongation in blood clearance associated with decreased liver and spleen activity following administration of 20 and 40 mg of antibody compared to the three lower antibody dose levels. Assuming a biodistribution similar to [111In]ZME-018, the radiation dose delivered to normal tissues by [90Y]ZME-018 would restrict its use as a routine vehicle for radioimmunotherapy; however, it may be possible to deliver substantial tumor doses in selected patients.

Reversibility bull's-eye: a new polar bull's-eye map to quantify reversibility of stress-induced SPECT thallium-201 myocardial perfusion defects.

Myocardial ischemia is currently interpreted from SPECT thallium-201 (201Tl) tomograms by the subjective visual finding of stress-induced perfusion defects which "normalize" or "reverse" by 4 hr. Thus, we have developed a computer method to quantify and display the three-dimensional distribution of reversible segments. Circumferential profiles generated from the short axis slices are normalized to the reference area in the stress study. The stress is subtracted from the normalized delayed data, and then displayed as a polar bull's-eye plot so that positive values show areas that have "reversed" or "improved." Patient profiles are compared to means and standard deviations of reversibility for all pixels determined from the Emory normal male files. Criteria for reversibility were developed from studies of 42 male patients found to have 48 defects, as determined by the consensus of five blinded expert observers. There was computer agreement with the experts on 25 of 31 relatively fixed and 14 of 17 reversible defects. Our preliminary results indicate that this new method promises to aid observers to more consistently identify and quantify the reversibility of SPECT 201Tl myocardial perfusion defects.