Rapid detection of acute appendicitis with Tc-99m-labeled intact polyvalent human immune globulin.

BACKGROUND: Acute appendicitis remains problematic for emergency clinicians. A rapid and definitive test is needed for detecting acute appendicitis before surgical intervention. The purpose of this clinical trial was to determine the efficacy of Tc-99m-labeled intact polyvalent human immune globulin (Tc-99m IgG) in the evaluation of acute appendicitis. STUDY DESIGN: Thirty-five patients with clinically suspected acute appendicitis were evaluated with Tc-99m IgG. After the intravenous injection of 25 mCi (92.5 MBq) of Tc-99m IgG, anterior flow, single photon emission computerized tomography (SPECT) and planar delayed images of the abdomen were obtained. Any abnormal focal uptake of Tc-99m IgG in the right lower quadrant was considered to be a positive scan. RESULTS: Twenty-one patients with a positive Tc-99m IgG scan underwent laparotomy and were found to have acute appendicitis. Of the 14 patients who had negative scans, 7 underwent surgery. In this series, Tc-99m IgG study yielded 21 true-positive, 12 true-negative, and 2 false-negative results with a sensitivity, specificity, and accuracy of 91%, 100%, and 94%, respectively. The positive and negative predictive values were 100% and 86%, respectively. There were no false-positive results. CONCLUSIONS: Tc-99m IgG scintigraphy can provide the clinicians a simple, rapid, and definitive test for the diagnosis of acute appendicitis.

Importance of the lateral view in the evaluation of suspected brain death.

The authors present two cases of clinical brain death that failed to meet the criteria for whole brain death using Tc-99m HMPAO. Conventional anterior cerebral flow studies demonstrated no intracerebral perfusion. Anterior static images also failed to show cerebral activity. However, the lateral images clearly demonstrate cerebellar activity. These cases demonstrate the importance of Tc-99m HMPAO as the agent of choice in evaluating brain death and the necessity of lateral views to meet the criteria for whole brain death. Cerebellar perfusion challenges the present criteria for whole brain death. New criteria must re-evaluate the present technology.

Scintigraphic detection of atherosclerotic plaques in rabbits with 111In-labeled hematoporphyrin derivative.

The efficacy of 111In-labeled hematoporphyrin derivative (HPD) in localizing and detecting atheromas had been investigated with 10 atherogenic New Zealand white rabbits. Atherosclerotic plaques surgically induced in the abdominal aorta showed selective uptake of 111In-HPD over normal blood vessels averaging 0.01% ID/g tissue (range 0.003-0.023% ID/g). Normal aorta and thoracic artery concentrated an average of 0.0026% ID/g which is less than the mean blood activity of 0.0034% ID/mL. Statistical analysis demonstrated significant difference in the uptake of 111In-HPD by the atherosclerotic plaque segments as compared to normal abdominal aorta (P = 0.0023) and normal thoracic artery (P = 0.0012). In hypercholesteremic rabbits, the mean plaque segment to normal blood vessels ratio was 4:1 (range 2 to 9:1) sufficiently high to permit plaque delineation in the scintigram. Although 111In-HPD showed promise as a plaque imaging agent, further investigation with large animal models such as primates is needed to confirm current findings.

Bone imaging findings in gangrene.

Review of three-phase bone imaging results in three patients with gangrene of the toes showed a unique pattern of absent perfusion and absent bony and soft-tissue uptake. In one of these patients, characteristic bone imaging findings were present before clear-cut clinical presentation. In our experience, the finding of absent uptake in a particular clinical setting is highly specific for gangrene.

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.

Carney's triad: radiographic diagnosis, natural history and importance of pulmonary chondromas.

We describe the radiographic findings and benign clinical course of a patient with two components of a triad of unusual neoplasms: pulmonary chondroma, gastric epithelioid leiomyosarcoma, and paraganglioma that may occur together in young women.

The relationship between radiographic findings and asymmetrical radioactivity in the shoulder.

A prospective study was performed to compare asymmetrical radioactivity in the shoulder on 99mTc bone scans with the conventional radiographic findings of 100 right-handed and 8 left-handed patients. Of the 100 right-handed patients, 30 had increased radioactivity in the right shoulder; 5 showed increased radioactivity on the left. Clinical history, shoulder physical examination, and site of injection did not influence the frequency of asymmetrical radioactivity; only dominant handedness correlated with this finding.