PubMed Health⌕ Search

Biomedical subjects

J K Siemsen

Publications and source records attributed to J K Siemsen.

At least 19 recordsLinked to original sources
PubMed1982

Metabolic and distribution studies with radiolabeled 5-fluorouracil.

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.

Adenocarcinoma↗
PubMed1980

Correlation of contrast angiography and histologic pattern with gallium uptake in primary liver-cell carcinoma: noncorrelation with alpha-feto protein. Concise communication.

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.

Angiography↗
PubMed1978

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.

Diagnosis, Differential↗
PubMed1978

A new noninvasive approach to peripheral vascular disease: thallium-201 leg scans.

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.

Arterial Occlusive Diseases↗
PubMed1978

Steroid-induced suppression of gallium uptake in tumors of the central nervous system: concise communication.

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.

Brain Neoplasms↗
PubMed1977

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

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.

Bone and Bones↗
PubMed1976

Gallium-67 scintigraphy of pulmonary diseases as a complement to radiography.

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.

Gallium Radioisotopes↗
PubMed1976

Gallium scanning in cerebral and cranial infections.

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.

Bone Diseases↗
PubMed1976

Transient brain scan abnormalities in renal dialysis patients.

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.

Adolescent↗
PubMed1976

Technetium-99m-glucoheptonate as a brain-scanning agent: critical comparison with pertechnetate.

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.

Adult↗
PubMed1975

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.

Arterial Occlusive Diseases↗
PubMed1975

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.

Chromatography, Gel↗
PubMed1975

Evaluation of postcraniotomy patients by radionuclide scan.

Twenty-eight patients with cerebral tumors were evaluated after craniotomy with combined radionuclide techniques in order to assess presence or absence of tumor recurrence. The combination of a positive pertechnetate or Tc-phosphate scan with a positive gallium scan strongly indicates the presence of recurrent or residual tumor. Infection may also cause uptake but was easily distinguished by the distribution. Negative gallium scans with positive technetium scans were indicative of non-recurrence in this series.

Brain Neoplasms↗
PubMed1975

Gallium gallbladder scanning in cholecystitis.

Gallium has been shown to accumulate in metabolically active tissue including sites of infection. The purpose of this study was to evaluate gallium scanning in cholecystitis. Ten patients with cholecystitis were studied using conventional gallium scanning techniques. Five patients with acute cholecystitis showed intense gallium accumulation in the gallbladder area. One of five patients with chronic cholecystitis showed significant accumulation in the gallbladder. The limitations of this method are mainly the need for serial scanning to rule out gallium accumulation in the hepatic flexure of the colon and also the failure to detect consistently a chronically diseased fibrotic gallbladder. We conclude that gallium scanning of the gallbladder is an important adjunctive study in the evaluation of cholecystitis.

Adult↗
PubMed1975

Scintigraphic elvaluation of liver metastases from thyroid carcinoma.

Thirty-one patients with carcinoma of the thyroid were evaluated using 131-I scan of the torso including the area of the liver. Focal areas of 131I uptake were found in the liver in two patients with follicular thyroid carcinoma. Both patients showed associated abnormalities on 99m-Tc-sulfur colloid liver scans. The remaining 29 patients showed either no uptake or a normal diffuse pattern of 131-I uptake in liver. Careful evaluation of the liver is recommended on the radioiodine body scan for metastases in patients with thyroid carcinoma.

Adenocarcinoma↗
PubMed1975

Calculation of relative weights for nuclear medicine procedures.

Relative weights for nuclear medicine procedures have been assigned previously on the basis of subjective estimates of resources expended. Thus, ultimate values frequently have not reflected time and cost of personnel and equipment accurately. Based on computerized data collected on over 8,000 patients, we have attempted to calculate relative weights more objectively by analyzing the following parameters: (A) physician time; (B) technologist time; (C) nurse (or aide) time; (D) equipment time and depreciation; and (E) radiopharmaceutical cost, or cost equivalent. Most major organ scans were found to have quite similar values whereas procedures with low ratings on previous value schedules were found to have high relative values when analyzed objectively.

California↗
PubMed1975

Evaluation of carcinoma of the cervix using 111In-bleomycin.

Indium-111 attached to bleomycin is useful in the scintigraphic localization of a variety of tumors. Since it does not normally accumulate in bowel and feces, it is superior to other radiopharmaceuticals, such as gallium-67 citrate, in the demonstration of abnormalities in the abdomen and pelvis. Twenty-eight patients with know carcinoma of the cervix were studied with whole body 111In-belomycin scans. Two "false-positive" scans were produced by local inflammation. Six "false-negative" scans were attributed to small tumors escaping scintigraphic detection. In the remaining 20 patients, scan findings correlated well with site and extent of the tumor as determined by other means. 111In-bleomycin scintiscanning may prove to be a highly useful adjunct in the evaluation of patients with carcinoma of the cervix.

Adenocarcinoma↗