Jan K. Siemsen

The use of gallium-67 in pulmonary disorders

Imaging of the chest cage with gallium-67 (67Ga) citrate is relatively easier to perform and interpret than imaging of the abdomen, because normally pulmonary concentration is low after 48 hr and physiologic accumulation in bones and breast can be recognized by its distribution. Modern scintillation detectors, particularly large field cameras with multiple pulse-height analyzers, give substantially better gallium images than those available in the past. Because of the nonspecific affinity of gallium through neoplastic and inflammatory processes, its value in the differential diagnosis of pulmonary diseases is limited. However, based on the literature and our own observations in over 1100 patients with established diagnosis of a variety of pulmonary diseases, we feel that the judicious use of 67Ga in selected patients is helpful in answering specific questions. These include preoperative evaluation of hilar and mediastinal involvement in pulmonary neoplasms, differential diagnosis of pulmonary infarctions and bacterial pneumonias, evaluation of pulmonary infiltrates regarding infectious etiology, follow-up of sarcoidosis on corticosteroid treatment, assessment of inflammatory activity in interstitial fibrosis and, in selected cases, early detection of neoplastic and inflammatory diseases before radiography becomes abnormal, such as diffuse carcinomatosis and Pneumocystis carinii infection. Potential large-scale application of pulmonary gallium imaging could be found in the screening of subjects exposed occupationally to noxious dust and in long-term serial follow-up of pulmonary tuberculosis patients for treatment response and reactivation. However, it remains to be seen whether gallium imaging statistically provides essential additional information in these indications when compared to cheaper conventional techniques.

Evaluation of 99mTc diphosphonate kinetics and bone scans in patients with Paget's disease before and after calcitonin treatment.

Eleven patients with Pagets disease of bone underwent serial total body bone scars before and after therapy with calcitonin. All patients studied showed improvement clinically as well as biochemically. Scan improvement was noted in patients with mild disease. Patients with severe disease showed either to change or only slight improvement on the serial bone scars The scan was of greatest value in determining the extent of disease, especially in 3 patients in whom biochemical values were normal. A single pulse injection of 50 M.R.C. units of salmon calcitonin produced a significant increase in the blood clearance of 99mTc diphosphonate. The mechanism of this effect is not clear from this study.

In vivo dynamic studies of hepatocyte function: A computer method for the interpretation of rose bengal kinetics

A model for the analysis of 131I rose bengal (rb) kinetics has been formulated based upon the known physiology of the hepatic processing of rose bengal. The method differs from other published techniques of quantitating hepatic function in that the physiology of the individual is considered in the analysis while allowing for the phenomena of regurgitation and blood background. The data are used directly as obtained and not modified prior to analysis. The method is more sensitive in detecting liver dysfunction than previously described single parameter methods. It is felt that this technique may be useful as a screen for hepatic dysfunction and an aid in the differential diagnosis of hepatic disease.

Are All Gallium Citrate Preparations the Same

Recent studies on brain imaging using 67Ga citrate from three different manufacturers revealed some clinical differences. Using chromatographic techniques, it was found that 67Ga citrate supplied by vendor A clearly differed from those of vendors B and C in mobility. When citrate was added to material of vendor B to bring the final concentration to 25 mg/ml, the chromatographic mobility increased dramatically. Addition of benzyl alcohol had no effect. The mechanisms involved in causing these chromatographic changes are not clear; however, the in vitro variations noted indicate a difference in chemistry which may ultimately affect the distribution and localization of the radiopharmaceutical.

Reliability of Gallium Brain Scanning in the Detection and Differentiation of Central Nervous System Lesions

Both 99mTc-pertechnetate and 67Ga-citrate brain scans were performed in 93 patients with cerebral neoplasms and in 70 others with cerebral infarction or hemorrhage. Tumor detection was clearly better with 67Ga(96%) than with 99mTc(85%). Cerebral infarctions consistently either failed to concentrate 67Ga(67%) of revealed a much lower concentration than the 99mTc study (27%). In 6% of the infarction patients, gallium and technetium scans were equivalent.

Combined Contrast and Radionuclide Angiography of the Liver

In 18 patients with known focal liver disease, intra-arterial radionuclide angiography and subsequent static scans were (a) found to be superior to contrast angiography in evaluation of small avascular hepatic lesions. (b) Radionuclide angiography was inferior to contrast angiography in evaluation of small hyper-vascular lesions. (c) Large vascular or avascular lesions were detected equally well by both methods. (d) Intravenous radionuclide perfusion distribution (“flow”) studies were equal or slightly inferior to the intra-arterial method in detecting hepatic lesions. (e) The intravenous radionuclide study was superior in determining arterialization of the hepatic bed. (f) Vascular lesions of the left lobe and inferior border of the liver were better detected by the intra-arterial injection of radiocolloid than by the intravenous route. (g) The combined use of all three techniques was superior to any single modality in evaluation of hepatic lesions.

Comparison of early and delayed technetium and mercury brain scanning.

The effectiveness of delayed 99mTc-pertechnetate brain scans (four hours) was compared with that of delayed scans obtained with 203Hg-chlormerodrin (24 hours), and both agents in turn were compared with early 99mTc (within one hour) and 203Hg scans (2 to 6 hours). A total of 109 lesions were evaluated with both radionuclides. Delayed scanning proved to be superior because of the increased yield obtained in most intracranial lesions. The delayed technetium scan should be the procedure of first choice. Delayed mercury scanning should be used when delayed technetium scans are negative or equivocal in a patient suspected of having a lesion adjacent to the base of the skull, especially in the subtentorial region.

Computer improvement of Anger Camera images

Abstract Data from the Anger Camera were obtained by means of a data acquisition computer or high resolution film reader and stored on magnetic tape. Correction for nonuniformity was obtained for camera flood and stored for processing incoming data. In addition, a method of contrast enhancement which allows the user to visualize the resulting image and its histogram is described.

Localization of 99m Tc-pyrophosphate in an islet cell tumor of the pancreas

A case of 99 mTc-pyrophosphate uptake in an islet cell tumor of the pancreas is presented. A possible relationship of pyrophosphate uptake in this tumor with uptake in other neuroectodermal tumors which are of neural crest origin is considered.

Nuclear Medicine Department Operational Analysis by Computer

Abstract A computer approach to the management of a nuclear medicine facility has been devised which facilitates the evaluation of departmental trends. The use of a simplified data form with appropriate codes gives us access to information not readily available with other techniques. This information allows us to optimize the operation of our facility and helps to create a valuable data base for future analysis based on data retrieval technology and statistics.