Technetium-99m-DTPA aerosol scintigraphy in amiodarone induced pulmonary toxicity in comparison with Ga-67 scintigraphy

Amiodarone hydrochloride, which is used in life-threatening cardiac tachyarrhythmia, has been known to cause amiodarone induced pulmonary toxicity (AIPT) as a complication. In this study we aimed to investigate the clinical value of technetium-99m diethylene triamine penta-acetic acid (DTPA) aerosol lung scintigraphy in patients with AIPT in comparison with gallium-67 (Ga-67) scan. The study group included 26 cases, 7 patients with diagnosis of AIPT (Group A), 8 patients receiving amiodarone therapy but without AIPT (Group B) and 11 healthy subjects as a control group (Group C). All patients underwent Ga-67 and Tc-99m-DTPA aerosol scintigraphy in addition to various laboratory tests, Ga-67 scintigraphy was positive in 4 of 7 AIPT patients but quite normal in Group B. A positive correlation was found (r = 0.52, p < 0.05) between kep values determined by Tc-99m-DTPA aerosol scintigraphy and the cumulative dose of amiodarone. The mean kep values were 2.04% +/- 0.85%/min, 1.30% +/- 0.42%/min and 0.86% +/- 0.19%/min for groups A, B and C, respectively. The mean clearance rate of group A was significantly faster than that of normals (p < 0.0005) and group B (p = 0.028). In addition, there was a significant difference between groups B and C (p = 0.015). In conclusion, Ga-67 lung scintigraphy is a useful method for the detection of AIPT but Tc-99m-DTPA aerosol scintigraphy offers better results than Ga-67 scintigraphy. Early changes in Tc-99m-DTPA clearance may be observed in patients receiving amiodarone. The kep value in patients with AIPT is noticeably increased with respect to the control group. With its favorable physical properties, low cost, lower radiation burden and its ability to be used as an objective measure for the pulmonary clearance rate, Tc-99m-DTPA aerosol scintigraphy appears to be promising in patients receiving amiodarone therapy.     

SPECT gallium-67 scanning in early human immunodeficiency virus (HIV) infection. Failure of scanning abnormalities to correlate with immunologic staging

The use of gallium scanning in the treatment of patients with AIDS has been well described. In this study, 27 HIV-infected patients (Walter Reed Staging Classification I-V) with normal chest roentgenograms were evaluated to determine the occurrence of thoracic gallium abnormalities in early HIV infection. SPECT was used for gallium scanning. Patients received gallium injection on day 1 and bronchoalveolar lavage on day 2, and scanning was performed on day 3. Twenty-eight scans in 27 patients were performed. Mean nodal SPECT activity was compared with corresponding values for lung parenchyma, bronchoalveolar lavage cell counts, and peripheral blood T4 lymphocyte counts. No relationship between nodal and parenchymal activity and cell counts was observed. Although visual scan interpretation was unaffected, gallium activity was significantly increased in the region of bronchoalveolar lavage compared with uptake in other lung regions. It is concluded that SPECT gallium scanning demonstrates significant gallium avidity in recently lavaged lung areas, although no impact on visual scan interpretation was seen. Further, no correlation was seen between the degree of nodal uptake and the immunologic status of these patients with early HIV infection.     

Technetium-99m pertechnetate and gallium-67 imaging in salivary gland disease

Thirty-two patients with salivary gland tumors or sialadenitis were studied with Tc-99m pertechnetate and Ga-67 imaging and, in some instances, sialography. The diagnostic algorithm presented allows the correct categorization of the salivary gland pathology in the vast majority of patients. The patients were studied serially with Tc-99m pertechnetate, Ga-67 and in certain situations sialography (or CT-sialography). Use of the algorithm can distinguish benign salivary tumors from malignant tumors and malignant tumors from inflammatory disease. The limitations and pitfalls of interpretation are discussed.     

Dual isotope scanning with gallium-67 citrate and technetium-99m radiopharmaceuticals

The interpretation of Ga-67 scans is limited by the complex anatomic and physiologic distribution of Ga-67 and by the low resolution possible with this isotope. The use of a second isotope Tc-99m, tagged to an appropriate pharmaceutical allows the identification of anatomic landmarks. Computer acquisition of both the Ga-67 and Tc-99m images allows for subtraction of the Tc-99m images from the Ga-67 images and leads to precise localization of abnormal Ga-67 accumulations. Only a small percentage of the counts in the Tc-99m window are due to Ga-67 scatter and do not degrade the Tc-99m images. Cases illustrating the value of the dual-isotope technique are presented.     

Gallium-67 scanning in the clinical evaluation of human immunodeficiency virus infection: Indications and limitations

This review, examines the indications for and limitations of gallium-67 (67Ga) scanning in the evaluation of patients infected with human immunodeficiency virus (HIV). The imaging protocol, as well as the normal biodistribution of 67Ga and its normal variants are discussed. The diagnostic significance of the different scintigraphic patterns that are found in acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) patients is reviewed. The use of 67Ga scintigraphy for measurement of the effectiveness of treatment in this patient population is also discussed, as is the likelihood that this examination could be used as a prognostic indicator in the future.     

Technetium-99m HM-PAO-labeled leukocytes in detection of inflammatory lesions: comparison with gallium-67 citrate

Forty-three patients with suspected benign, inflammatory, or infectious diseases were imaged with [99mTc]HM-PAO-labeled leukocytes and [67Ga]citrate. Technetium-99m leukocytes showed 22 true-positive, no false-positive, 19 true-negative, and two false-negative findings and [67Ga]citrate 23, 7, 12 and 1, respectively. The sensitivity, specificity, and accuracy values with 99mTc leukocytes were 92%, 100%, and 95%, and with [67Ga]citrate 96%, 63%, and 81%. Technetium-99m leukocyte scintigraphy has a promising future in comparison with [67Ga]citrate because of the ready availability of [99mTc]HM-PAO, the good image quality, more rapid results (within few hours), and the lower radiation exposure to the patient with 99mTc leukocytes. The usefulness of 99mTc leukocytes in chronic osteomyelitis needs further evaluation.     

Technetium-99m DTPA aerosol and gallium scanning in acquired immune deficiency syndrome

In 11 non-smoking AIDS patients suspected of pneumocystis carinii pneumonia (PCP), the results of Tc-99m DTPA aerosol clearances, gallium scans, and arterial blood gases were compared with those of bronchoalveolar lavage (BAL). Nine patients had PCP. All had increased clearances five times higher than the normal (5.6 +/- 2.3% X min-1 vs 1.1 +/- 0.34% X min-1, N = 10, P less than 0.001), suggesting an increased alveolar permeability. Gallium scans were abnormal in six patients but normal or slightly abnormal in the three others. Four of these nine patients had normal chest x-rays. In two of these the gallium scan was abnormal, but in the two others, only the increased Tc-99m DTPA clearances showed evidence of lung disease. Two patients had normal BAL, with normal clearances and gallium scans. Four out of the nine patients with PCP were studied after treatment. Three recovered and had normal clearance and gallium scans. One still had PCP with increased clearance but normal gallium scan. Gallium scanning and Tc-99m DTPA clearance are useful for detecting lung disease in AIDS patients with suspected PCP and for prompting BAL when chest x-rays and PaO2 levels are normal. Due to its high sensitivity, a normal Tc-99m DTPA clearance could avoid BAL.     

Thyroid scanning with gallium-67 and cesium-131.

The roles of 131Cs and 67Ga in the evaluation of solitary thyroid nodules were investigated. Radionuclide scans were performed with 67Ga and 131I in 27 patients and with 131Cs and 131I in 43 patients. Gallium-67 detected only two of eight malignant nonfunctioning nodules and 131Cs detected one of three such nodules. The contribution of 131Cs and 67Ga to the preoperative identification of malignant thyroid lesions is of doubtful value.     

Comparison of technetium-99m methoxyisobutylisonitrile and gallium-67 citrate scanning in the assessment of lymphomas

The aim of this study was to compare the value of scintigraphy using technetium-99m methoxy-isobutylisonitrile (MIBI) with that of scintigraphy using gallium-67 citrate in the assessment of Hodgkin's disease and non-Hodgkin's lymphoma and to relate these results with those of CT scan and MRI. Fifty-eight patients were included either for a follow-up examination or for monitoring of their treatment. Twenty-three residual masses were studied. A whole-body scan was performed, followed by single-photon emission computed tomography (SPET) 20 min after injection of 740 MBq of^99mTc-MIBI and 72 h after injection of 185 MBq of⁶⁷Ga citrate. The overall sensitivity of^99mTc-MIBI and⁶⁷Ga citrate was 71% and 68%, respectively, and the overall specificity was 76% and 44%, respectively. For residual masses, the sensitivity was 44% with both tracers and the specificity was 80% with^99mTc-MIBI and 53% with⁶⁷Ga citrate. The positive predictive values were 85% and 68% and the negative predictive values were 59% and 44%, respectively. The signal-to-background ratio was 1.5 for^99mTc-MIBI and 2 for⁶⁷Ga citrate. At present,^99mTc-MIBI cannot replace⁶⁷Ga citrate in the assessment of lymphomas.     

Computerized double-tracer subtraction scanning with gallium-67 citrate in inflammatory diseases.

A gallium-67/technetium-99m subtraction technique was used with a variable weighting factor. That is, each image was separately set to 100%. Varying amounts of the Tc-99m images were subtracted from those of Ga-67. A total of 95 patients who had radiogallium scanning for suspected inflammatory disease were studied by the subtraction technique. Thirty of these patients had abnormal Tc-99m pyrophosphate bone scans, while 20 had abnormal radiogallium abdominal foci; 45 had defects in liver, spleen, or kidney images. The subtraction technique with variable weighting was highly successful in enhancing hot-spot visibility, and in providing information as to the anatomic location of the defect.     

The usefulness of gallium-67 citrate scanning in testicular seminoma

An analysis of 77 consecutive patients with a histologic diagnosis of seminoma testis, assessed and treated at the Cross Cancer Institute between 1977 and 1982, is presented. Ga-67 citrate was first used in the assessment of patients with malignant testicular tumors in 1973. Following three years of study that supported the observation of the gallium-avid nature of seminoma, gallium scans became routine in the initial staging assessment and were used also when recurrence was suspected. From 1977 through 1982, 72 patients with biopsy-proven seminoma testis were assessed initially for extent of disease by Ga-67 scanning. Comparison with intravenous pyelography and bipedal lymphography was possible for accuracy of tumor assessment. The scan sensitivity was 83%, and the specificity was 95%. During the same period, gallium was studied in nonseminomatous testicular tumors but the results were disappointing and its use was discontinued. The gallium-avid nature of seminoma testis may be useful in determining the extent of disease.     

Semi-quantitative gallium-67 lung scanning as a measure of the intensity of alveolitis in pulmonary sarcoidosis

Gallium-67 (⁶⁷Ga) lung scanning has been applied for some years in pulmonary sarcoidosis to assess the activity of the alveolitis. Interpreting the scans, however, is difficult due to the low uptake of ⁶⁷Ga in the disease process relative to background activity. In this study we have measured the mean parenchymal lung activity of ⁶⁷Ga and have compared the lung activity to that at three remote sites, the liver, the abdomen and the thigh. The results obtained were compared with the percentage of lymphocytes in broncho-alveolar lavage fluid. There was a very good correlation with the lung-to-thigh uptake measurements and a much poorer correlation with the lung-to-liver and the lung-to-abdomen measurements. It was observed that steroid therapy reduced dramatically the correlation between the broncho-alveolar lavage findings and the ⁶⁷Ga scan measurements. The results suggest that in patients not on steroid therapy, the ⁶⁷Ga lung-to-thigh measurements may be used, similarly to the broncho-alveolar lavage lymphocyte counts, to identify those with high-intensity alveolitis from those with low-intensity alveolitis.     

Radiographic findings in pulmonary tuberculosis: the influence of human immunodeficiency virus infection.

The chest radiographs and medical records of 166 patients diagnosed as having clinically active pulmonary tuberculosis were reviewed. Forty-nine patients (group I) were seropositives to human immunodeficiency virus (HIV), and 117 patients (group II) did not have known risk factors for HIV infection. Roentgenographic abnormalities were analysed in the two groups, according to nine different radiographic patterns previously defined. The seropositive group had a significantly higher proportion of hilar and/or mediastinal adenopathy (P less than 0.001), infiltrates confined to the lower lung fields (P less than 0.05), and miliary tuberculosis (P less than 0.005). Otherwise, single cavitation and destructive pattern were more frequent in the group II. These data suggest that patients with pulmonary tuberculosis and HIV infection are much more likely to have atypical radiographic findings.     

Semi-quantitative gallium-67 lung scanning as a measure of the intensity of alveolitis in pulmonary sarcoidosis

Gallium-67 (67Ga) lung scanning has been applied for some years in pulmonary sarcoidosis to assess the activity of the alveolitis. Interpreting the scans, however, is difficult due to the low uptake of 67Ga in the disease process relative to background activity. In this study we have measured the mean parenchymal lung activity of 67Ga and have compared the lung activity to that at three remote sites, the liver, the abdomen and the thigh. The results obtained were compared with the percentage of lymphocytes in broncho-alveolar lavage fluid. There was a very good correlation with the lung-to-thigh uptake measurements and a much poorer correlation with the lung-to-liver and the lung-to-abdomen measurements. It was observed that steroid therapy reduced dramatically the correlation between the broncho-alveolar lavage findings and the 67Ga scan measurements. The results suggest that in patients not on steroid therapy, the 67Ga lung-to-thigh measurements may be used, similarly to the broncho-alveolar lavage lymphocyte counts, to identify those with high-intensity alveolitis from those with low-intensity alveolitis.     

Tc-99m-DTPA aerosol and radioactive gases compared as adjuncts to perfusion scintigraphy in patients with suspected pulmonary embolism

To evaluate the clinical utility of improved methods for radioaerosol inhalation imaging, we obtained preperfusion radioaerosol images in 107 patients (mean age = 62 years), who were referred for evaluation of suspected pulmonary embolism (PE). For each patient, we compared six-view aerosol images with accompanying perfusion scans and chest radiographs and with Xenon-133 (Xe-133) or Krypton-81m (Kr-81m) studies. Four observers at four different institutions independently evaluated aerosol-perfusion and gas-perfusion pairs, classifying the probability of PE as low, high, or indeterminate. The radioaerosol images were good to excellent in quality; excessive central deposition of activity was infrequent and did not interfere with image interpretation. The aerosol-perfusion studies showed 86% agreement with Xe-133 perfusion interpretations (n = 299) and 80% agreement with Kr-81m perfusion interpretations (n = 99). These rates of agreement were comparable with those of intraobserver agreement for gas-to-gas and aerosol-to-aerosol comparisons, and higher than interobserver agreement rates. In a limited number (n = 9) of angiographically documented cases, aerosol-perfusion and gas-perfusion studies provided accurate and equivalent diagnoses. The results suggest that radioaerosol inhalation studies, performed with improved nebulizers, are diagnostically equivalent to ventilation imaging as an adjunct to perfusion scintigraphy in evaluating patients with suspected PE.     

Absence of gallium-67 avidity in diffuse pulmonary calcification

Diffuse pulmonary uptake by bone-seeking radiopharmaceuticals has been reported previously but, in the same patient, would pulmonary uptake of Ga-67 citrate yield clinically meaningful results? A patient with hypercalcemia and renal failure in whom bone scintigraphy demonstrated striking diffuse bilateral pulmonary uptake, but subsequent gallium imaging demonstrated no evidence of pulmonary uptake greater than body background, is discussed. We conclude that pulmonary uptake of gallium cannot be attributed to calcium deposition and should carry the same clinical significance in regard to inflammatory and malignant lesions as would be assigned to patients without pulmonary calcific deposits.     

Lymphocytic interstitial pneumonitis: a cause of pulmonary gallium-67 uptake in a child with acquired immunodeficiency syndrome

Lymphocytic interstitial pneumonitis (LIP) is currently recognized as a frequent pediatric manifestation of the acquired immunodeficiency syndrome (AIDS). We report the gallium scan findings in a 3-yr-old girl with this disorder and review its clinical, radiologic, and pathologic features. LIP must be a prime consideration in the differential diagnosis of diffuse pulmonary gallium uptake in pediatric AIDS patients. Further experience will afford greater perspective on the diagnostic role that nuclear medicine will ultimately play in this disease.     

Technetium-99m-MIBI and thallium-201 uptake in pulmonary actinomycosis

A patient with pulmonary actinomycosis who unexpectedly showed focal uptake of technetium-99m-hexakis-2-methoxy isobutyl isonitrile and thallium-201 is presented. The appearance of the lesion on the chest radiograph and x-ray CT scan resembled a mediastinal tumor. The diagnosis of pulmonary actinomycosis was achieved by histopathologic examination of the surgically removed mass.