Biomedical subjects
Publications and source records attributed to G B Hopkins.
A simple ventricular phantom has been constructed to validate calculations of ejection fraction in radionuclide ECG-gated equilibrium studies. The R-wave stimulator constructed from one integrated circuit can also be used as a stand alone device for testing computer interface and cable connections for the ECG R-wave synchronizer input.
In 22 volunteers without clinical or laboratory evidence of liver disease, liver volume was determined using single-photon emission computed tomography (ECT). This technique provided excellent object contrast between the liver and its surroundings and permitted calculation of liver volume without geometric assumptions about the liver's configuration. Reproducibility of results was satisfactory, with a root-mean-square error of less than 6% between duplicate measurements in 15 individuals. The volume measurements were validated by the use of phantoms.
Delineation of the metastatic spread of lung cancer has been attempted by a variety of means. Controversy as to the indications for organ surveys, mediastinoscopy, scintillation scanning, and biopsy techniques still exists. Since definition of the micrometastatic state is yet unachieved, the staging of disease for therapy continues to be predicted on documented spread beyond the site of the origin. The records of 75 patients in whom the presence or absence of mediastinal metastases was known were retrospectively reviewed to establish the sensitivity, specificity, predictive values, and accuracy of 67Ga scintigrams. Comparisons were made with chest roentgenograms, mediastinal tomograms, and endoscopic findings. Five patients had 67Ga-negative studies. In the 70 patients having 67Ga-positive lung lesions, mediastinal 67Ga uptake had a sensitivity of 88%, a specificity of 86%, predictive values of 93% for a positive test and 76% for a negative test, and a test accuracy of 87%. These studies, plus those of others, permit selectivity of choosing candidates for mediastinoscopy. If the primary is 67Ga positive, a negative mediastinal scan obviates mediastinoscopy. If the mediastinum is 67Ga positive, mediastinal exploration is indicated. The level of involvement dictates whether resection is undertaken in suitable surgical candidates. This approach, employed since 1976, has lowered the costs of staging, and 67Ga has become our scintigram of choice.
Thirty-five patients with coronary artery disease and possible left ventricular aneurysm underwent routine clinical examination, gated cardiac blood pool scintigraphy, and radionuclide cineangiography. Thirty-three of the 35 patients had coronary angiography and contrast left ventriculography. Sixteen patients had segmental left ventricular akinesia or dyskinesia, and 17 demonstrated left ventricular hypokinesis on contrast ventriculograms. Two patients had aneurysm confirmed at autopsy. Routine clinical evaluation was not sufficient to separate patients with aneurysm from those with hypokinesis. Radionuclide cineangiography correctly identified all cases of aneurysm or hypokinesis. The cinescintigraphic technique was preferable to the gated cardiac blood pool technique for qualitatively assessing and classifying abnormal ventricular wall motion. There was good correlation of the left ventricular ejection fraction by contrast ventriculograms and gated scintigrams in patients with either aneurysm or hypokinesis.
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Cardiac wall motion was evaluated in 54 patients by ECG-gated blood pool scintigraphy (GBPS) and computer assisted cine-radionuclide-equilibrium study (CRES). The cine format in CRES enhances the subtle aspects of great vessel and cardiac chamber motion and volume abnormalities. An off-line system using a general purpose computer permitted CRES to be initiated in smaller nuclear medicine facilities without large financial investiments.
ECG-gated images were processed by a computer using a nonlinear digital filter and directional masks to improve delineation of cardiac chamber boundaries and identification of the aortic and mitral valve planes. This technique proved to be satisfactory in 30 patients with documented coronary or valvular heart disease.
Ninety-one patients with chest pain suggestive of acute myocardial infarction were studied by static technetium Tc 99m stannous pyrophosphate scintigraphy and dynamic sodium pertechnetate Tc 99m cardioangiography. Twenty-three of 26 patients (88%) with acute transmural infarcts and 12 of 17 patients (71%) with nontransmural infarcts had abnormal static studies. In 45 patients with negative scintigrams, ECG or serum enzyme changes consistent with acute infarction failed to develop. Three false-positive static studies (6%) were recorded. Twenty of 43 (47%) patients with acute infarction had hemodynamic or structural abnormalities identified by cardioangiography. The dynamic study also proved helpful in localizing the site of infarction and in ruling out certain causes of false-positive static scintigrams.
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Four patients with suspected perinephric abscess were evaluated by gallium-67 scintigraphy. Gallium-67 scintigraphs proved instrumental in correctly diagnosing and localizing 4 left perinephric abscesses. Roentgenographic examinations were negative in 2 cases. Gallium-67 scintigraphy can be a useful non-invasive technique to evaluate patients with suspected perinephric abscess.
Unilateral 67Ga uptake was observed in the left breast of a 23-year-old woman who had nursed her infant on that side for 10 months. Careful clinical examination and follow-up failed to reveal any evidence of breast disease. Unilateral breast feeding should be considered in the differential diagnosis of asymmetric 67Ga localization in the breast.
In 140 patients with suspected intraabdominal abscess, studies were made using gallium-67 citrate and technetium-99m labeled radiopharmaceuticals. Gallium-67 scintigrams correctly localized 52 of 56 intraabdominal abscesses confirmed at surgical operation or necropsy. In an additional 20 patients in whom findings on scintigrams were abnormal, there were clinically established infections. Sixty-one patients in whom findings on scintigrams were normal were conservatively managed and discharged from the hospital; none proved to have an abscess. Four false-negative and three false-positive studies were recorded. Gallium-67 scintigraphy is a useful noninvasive diagnostic adjunct that should be employed early in the evaluation of patients with suspected intraabdominal sepsis.
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Forty postoperative patients with clinical and roentgenographic findings suggestive of subphrenic abscess were evaluated by early and delayed 67Ga scintigraphy. Early 67Ga scintigraphs obtained 6 hr after injection correctly localized seven right and five left subphrenic abscesses. In no instance was an abscess present on delayed scintigraphs that was not evident on the 6-hr study. Two patients with left subphrenic abscess had false-negative results on both early and delayed scintigraphy. No false-positive studies were recorded. Early 67Ga scintigraphy can be a valuable noninvasive adjunct of the diagnosis of subphrenic abscess.
Four septic patients with suspected subphrenic abscess were evaluated with gallium-67 citrate and technetium-99m labeled radiopharmaceuticals. Gallium-67 scintigraphs proved instrumental in correctly diagnosing and localizing one left and three right subphrenic abscesses. Gallium-67 scintigraphy can be a useful noninvasive technique for evaluating patients with suspected subphrenic abscess.
Sixty patients suspected of having abdominal abscesses were evaluated by early and delayed 67Ga scintigraphy. The 67Ga scintigraphs obtained 6 hr after injection correctly localized 18 of 20 abdominal or retroperitoneal abscesses. An additional 13 patients with abnormal scintigraphs had clinically established infections. In no instance was an abscess or inflammatory focus present on delayed scintigraphs that was no evident on the 6-hr study. Two false-positive and two false-negative studies were recorded. Early 67Ga scintigraphy is warranted in patients with suspected abdominal abscesses.
Skeletal scintigraphy using Technetium-99m ((99m)Tc) complexes was carried out in a series of 332 cancer patients. The results of scintigraphy were compared with the results of roentgenography and with the diagnostic usefulness of serum alkaline and acid phosphatase levels and the presence or absence of bone pain. In 25 percent of cases, lesions were first identified with scintigraphs. When metastastic lesions were present on both scintigraphs and roentgenograms, the number was greater on scintigraphs in 72 percent of cases. Six false negative studies were recorded (1 percent). Sixty percent of patients with early metastasis-that is, those with abnormal scintigraphs and negative roentgenograms-were asymptomatic. Serum alkaline and acid phosphatase levels were normal in 40 percent and 42 percent respectively of those with early skeletal involvement. Skeletal scintigraphy with (99m)Tc complexes is superior to other commonly employed techniques used to assess bone metastasis.
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