RESUMEN

Thallium 201 myocardial perfusion scanning revealed focal left ventricular defects at rest in four of 30 patients (13 percent) with systemic sarcoidosis. All the defects decreased in size during thallium stress imaging, a finding opposite of that usually seen in myocardial ischemia. Nine patients had abnormal right ventricular visualization at rest. Thus, 11 of 30 (37 percent) had abnormal resting myocardial scand. Two of the four patients with left ventricular defects were studied serially for up to 1.5 years to evaluate response to corticosteroid therapy. The myocardial defect diminished in one patient, whereas the second patient, maintained for 2 years on low doses of steroids, had no resolution. In patients suspected of focal myocardial involvement by sarcoidosis on thallium scanning dynamic changes in scan defects can occur during exercise which are the reverse of those usually seen in coronary artery disease. These defects probably represent myocardial sarcoid. Right ventricular uptake generally appears to correlate with the severity of pulmonary involvement by sarcoidosis, yet does not appear to be a specific finding.

Asunto(s)

RESUMEN

Prospective analysis of the efficacy of 99mTc-IDA cholescintigraphy and cholecystosonography showed that both are excellent techniques for assessing patients with suspected acute cholecystitis (accuracy 84.7% and 88.1% respectively). Consequently, the choice of tests selected to evaluate patients with suspected acute cholecystitis depends on several factors including; (a.) quality of equipment available; (b.) capability of the technologist performing the examination; (c.) relative experience of the physician supervising the examination; and (d.) willingness of the surgical consultant to accept a positive examination as sufficient evidence to perform emergency surgery. The authors feel that cholecystosonography should be used to assess the presence of acute cholecystitis in jaundiced patients because of its capability in the assessment of bile duct dilatation, and because of the lower reliability of cholescintigraphy when bile duct obstruction is possible (i.e., in jaundice). Ancillary findings in cholecystosonography and cholescintigraphy can aid in the differential diagnosis of acute right upper quandrant pain syndromes.

Asunto(s)

RESUMEN

5-Fluorouracil (5-FU) is an effective anti-tumor drug, which has been used both as a single agent and in combination with other chemotherapeutic agents for the treatment of tumors such as breast and colorectal carcinoma. We synthesized 5-FU with trace amounts of 18F-5-FU and administered the compounds intravenously to 6 cancer patients. The patients were scanned at 2 hr intervals for 12 hrs and their urine collected whenever possible. We also injected 5-FU with the tracer 18F-5-FU, at pharmacological doses, into non-tumored rats, and sampled their bile and blood for 95 mins post-injection. For comparison, 2-14C-5-FU was injected into non-tumored rats and their bile and blood sampled at the same intervals. Minute quantities of rat bile and serum were analyzed chromatographically by high-performance TLC. 5-FU and two of its metabolites (FBAL and FUPA) were identified and quantified by this technique. Both percentage and absolute amounts of 5-FU in the bile follow comparative kinetic patterns. While the liver and the urinary bladder were clearly observable in all 16 patients, the detectability of the gall-bladder was correlated to the inverse of the alkaline phosphatase level in the blood. This work suggests that the diversity of the 5-FU metabolism in cancer patients may allow the use of 18F-5-FU as a probe for understanding those individual variabilities in clinical situations.

Asunto(s)

RESUMEN

The relative distribution, metabolism and kinetics of 18F containing compounds, following administration of 18F-5-fluorouracil, has been proposed as a prognostic aid in predicting response to 5-fluorouracil chemotherapy. Because 18F has a relatively short physical half-life (t1/2 = 110 min), and the distribution and kinetics of the radiolabeled 5-fluorouracil need to be studied over periods of time that range over several half-lives of the radionuclide, significant quantities of the labeled drug must be administered in order to obtain good counting statistics. The distribution of 18F, following injection of 18F-5-fluorouracil to rats and mice, has been well documented in our previous work. It appears that the distribution of 18F in humans, following administration of 18F-5-fluorouracil is similar to that in rats. We calculated the radiation dose according to the MIRD technique for the eleven main target organs for a reference man. The critical organs, according to these calculations, are the bladder wall, the kidney and the liver, receiving a radiation dose of 729, 184 and 114 mrad per mCi injected, respectively.

Asunto(s)

RESUMEN

Eighteen patients with multiple myeloma were studied using radiographs of the skeletal system, technetium phosphate bone scans, and gallium-67 scintigraphy. A total of 94 sites were used as the basis for comparison in these 18 patients. Radiographic sensitivity on a patient basis was 94%, and was 82% on a site basis. Bone scans were positive in 78% of patients and in 46% of sites. Gallium scans were positive in 56% of patients and 40% of sites. In five of the 18 patients, gallium scans showed activity in abnormal sites with a greater lesion-to-nonlesion ratio than did the bone scan. In this subgroup of patients, the disease was fulminant, and all died within 3 mo of their study. The finding of high gallium uptake in osseous sites that are normal or only slightly abnormal on bone scan has served to identify a subgroup of patients with rapidly progressive disease who may benefit from alternative treatment modalities such as radiation therapy.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

Seventeen patients with histologically proven primary liver-cell carcinoma were evaluated by a technetium-99m sulfur colloid liver scan as well as with gallium-67 citrate. Twelve of the 17 patients (71%) showed gallium uptake in the tumor. Eleven of the 12 patients (92%) with a moderately or well-differentiated tumor showed increased gallium activity in the abnormality seen on the sulfur colloid scan. The exception in this group was a tumor with a large central area of necrosis. Four of five patients with a poorly differentiated or atypical carcinoma showed absence of gallium activity. Only six of 11 patients with a hypervascular tumor showed a marked increase in gallium uptake. Correlation of gallium with alpha-feto-protein, and with hepatitis antigen A, was poor. We conclude that gallium uptake in primary liver-cell carcinoma will be significant when the tumor shows a moderately to well-differentiated histologic pattern, unless significant necrosis is present. If the blood supply is markedly impaired, gallium uptake is reduced. However, a hypervascular blood supply does not necessarily ensure increased gallium avidity.

Asunto(s)

RESUMEN

Calcitonin has been used in the treatment of Paget's disease of bone, and serum alkaline phosphatase level and 24 hr urinary hydroxyproline excretion have been used to follow therapeutic response. The radionuclide bone scan has been used as a visual indicator; however, there is some uncertainty as to its value in following changes in disease activity. Four patients with both serial technetium phosphate bone scans and serial gallium studies were studied. In each case the beneficial effect of calcitonin was demonstrated more accurately with gallium than with technetium diphosphonate. Since biochemical changes in Paget's disease are believed to be mediated at the cellular level and gallium uptake depends on cellular activity, it is proposed that gallium uptake is a more appropriate measure of the activity of Paget's disease than a noncellular marker such as a technetium-containing bone scan agent.

Asunto(s)

RESUMEN

A new noninvasive technique to evaluate blood flow distribution to the legs is described. Intravenous thallium-201 is used during rest and exercise followed by scanning and point counting of the lower extremities. The normal blood flow distribution recorded in 30 patients with no known peripheral vascular disease was primarily proportional to muscle mass. Using both scans and point counting, normal intra- and interextremity ratios were qualitatively and quantitatively defined, and significant increases in muscular to nonmuscular perfusion with exercise were documented. The symmetry in perfusion in the contralateral muscle groups was verified for the first time.

Asunto(s)

RESUMEN

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.

Asunto(s)

RESUMEN

A case of 99m Tc-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.

Asunto(s)

RESUMEN

The effect of steroids given in greater than replacement doses on the gallium and technetium glucoheptonate brain scan is evaluated by comparing the relative sensitivity of both radiopharmaceuticals in patients both on and off steroids. The study shows a significant steroid effect on the sensitivity of 95% to 64% following steroids. Steroids did not significantly alter the sensitivity of the technetium glucoheptonate study. The superiority of the TcGH brain scan over the gallium citrate brain scan in the steroid population suggests a difference in the uptake mechanism for the two radiopharmaceuticals.

Asunto(s)

RESUMEN

Eleven patients with Paget's 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.

Asunto(s)

RESUMEN

Eighteen patients with cranial or intracranial infections were studied with technetium and gallium brain scans. Seven of 18 lesions were noted with gallium and not with pertechnetate, while the reverse pattern was not seen. Brain abscesses were visualized with gallium but not with pertechnetate in two of five cases. Osteomyelitis of the skull and mastoiditis showed intense gallium uptake in all cases, meningitis or cerebritis gave inconsistent results.

Asunto(s)

RESUMEN

Delayed 99mTc-glucoheptonate and pertechnetate scans were evaluated in a paired study for their ability to detect brain lesions. Glucoheptonate was found to be superior in eight of 17 cases of brain tumor and in two of ten patients with cerebral infarction. In addition, early (30 min) 99mTc-glucoheptonate brain scans were compared with delayed studies: the former were inferior in 48% of the cases. We conclude that 99mTc-glucoheptonate is a promising agent for delayed brain scanning, offering better lesion detection than pertechnetate.

Asunto(s)

RESUMEN

Gallium chest scans of 575 patients were analyzed for their clinical usefulness in conjunction with chest radiographs. The series included patients with pulmonary carcinoma, lymphoma, tuberculosis, sarcoidosis, pneumoconiosis, and interstitial fibrosis. Gallum scintigraphy does not aid in the differential diagnosis of pulmonary diseases but is helpful in determining (a) the degree of activity of a known disease process: (b) treatment response, dosage, and duration; (c) the spatial extent of the disease; and (d) the presence of unsuspected disease foci hidden radiographically in the mediastinum, behind the heart, or in pleural or parenchymal scars.

Asunto(s)

RESUMEN

Two patients on chronic renal hemodialysis developed acute neurologic symptoms and unusual brain scan findings, including very prominent cranial sinuses. Symptoms and scan abnormalities reverted to normal within a few days. The possible mechanisms are discussed.

Asunto(s)