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At least 523 records · Page 29Linked to original sources
PubMed1985

A Walker 256 tumor-induced osteogenic small animal model for the evaluation of [99mTc] diphosphonate radiopharmaceuticals.

A mammalian model has been developed for the in vivo evaluation of bone imaging agents. The model is based upon the quantification of a discrete, initial secondary periosteal osteogenesis induced in cortical bone immediately adjacent to an intramuscularly implanted Walker 256 tumor in Fisher 344 rats. Evaluation of the model consists of a histopathological examination of the periosteal bone formation, biodistribution studies on 99mTc-MDP and 99mTc-HMDP commercial kit preparations, and biodistribution studies on two 99mTc-HEDP component fractions isolated after anion exchange chromatographic separations from an investigative "carrier added" preparation. Reversed phase HPLC separations of the 99mTc-MDP and 99mTc-HMDP commercial kit preparations illustrate distinct differences in chemical composition between the two bone agents.

Animals↗
PubMed1985

A simplified technique for quantifying 24-h whole body retention of 99mTc-labeled methylene diphosphonate (MDP).

A simple technique for measuring 24-h whole-body retention (24-h WBR) of 99mTc-labeled methylene diphosphonate (MDP) is described. We chose a standard thyroid probe-scaler system (Picker-Magna Scanner) as our counting instrument and characterized it relative to: photon saturability; optimum counting time post administration; patient positioning; and results with prostate cancer patients with positive/negative scintigram diagnoses for bone metastases. Whole body retention values of 99mTc at 24 h were easily measured with our instrumentation. Initially whole body count rates were determined at 5-min post injection and, again at 24 h. Data accumulated prior to the 5-min time period were inaccurate due to a higher sensitivity for the activity in the early circulation. Also, initial count rates obtained from patients injected with (740 MBq) (20 mCi) 99mTc-MDP usually required a correction due to detector saturation. The data observed at 24 h, representing skeletal tracer uptake, required no such correction. Patient positioning was rigorously controlled for the two time intervals to insure constant geometry. The 24 h-WBR values measured for prostate cancer patients with positive bone scintigrams was significantly different from those patients with negative scintigrams (58.8 +/- 8.7% and 29.2 +/- 9.6% respectively). Measurement of the 24 h-WBR has great potential for following various pathologies in the clinical setting.

Bone Neoplasms↗
PubMed1983

99mTc-DMSA scanning to diagnose pyelonephritic scarring in children.

99mTechnetium-labeled dimercaptosuccinic acid (99mTc-DMSA) scanning provides superior quality images of renal parenchymal detail, which makes it highly sensitive for the diagnosis of pyelonephritic scarring. Unlike most other imaging techniques, radionuclide scanning is not affected by bowel gas or bony structures overlying the kidneys. This makes it particularly useful in children. Furthermore, renal scarring can be demonstrated by 99mTc-DMSA even before the classic gross anatomic and radiologic changes are present. The use of 99mTc-DMSA scanning in over 300 children has demonstrated its benefits and advantages over standard radiographic techniques.

Adolescent↗
PubMed1985

Clinical evaluation of 99mTc-DMSA renogram.

Two hundred-two 99mTc-DMSA renograms for urologic problems were evaluated. Some technical aspects of the examination and the value of the scintigraphic depth estimation are discussed. Pre- and postoperative uptake values in patients with renal surgery and sequential postoperative examinations are considered. The value of DMSA renograms in predicting recovery in obstructive uropathy and in deciding to opt for conservative therapy or nephrectomy is discussed.

Aged↗
PubMed1992

Lymphoscintigraphy in vulvar cancer: a pilot study.

This pilot study was undertaken to correlate the patterns of lymphatic drainage demonstrated by vulvar lymphoscintigraphy with the clinical and pathologic findings of the inguino-femoral lymph nodes in patients with vulvar cancer. Ten patients were studied with the radionuclide Technetium-antimony trisulfide colloid (Tc 99m ASC) using a perilesional technique. Images were obtained at 2-4 hr postinjection. Four of the six patients with central lesions or lesions that crossed the midline had bilateral groin uptake, and two had unilateral uptake to the side on which the lesion was predominantly located. Three of these patients, each with suspicious groin nodes bilaterally, had metastatic nodal disease, two unilateral and one bilateral, in whom the uptake was bilateral and unilateral, respectively. Three of the four patients with unilateral lesions had ipsilateral groin drainage only and one had no drainage. Three underwent a bilateral lymphadenectomy and none had metastasis. The pattern of Tc 99m ASC uptake was not predictive of metastatic nodal disease. In two of the three patients with unilateral groin recurrence the side of recurrence was the same as that demonstrated on lymphoscintigraphy, and in the third case there was bilateral drainage. Further data are needed to determine the role of lymphoscintigraphy in the management of vulvar cancer.

Aged↗
PubMed1991

Rib infarcts and acute chest syndrome in sickle cell diseases.

In the absence of evidence for pneumonia or pulmonary embolus, primary pulmonary infarction has been assumed to be the cause of the syndrome of chest pain, fever, and pulmonary infiltrate on chest X-ray that commonly complicates sickle cell anaemia. To find out whether the syndrome might be due to rib infarction, 99mTc-diphosphonate bone scans were done. In the eleven episodes thus investigated (10 patients) the scans showed segmental areas of increased radionuclide uptake in ribs, indicative of bone infarction. A possible sequence of events is that the rib infarcts are primary and cause bone pain, followed by soft tissue reaction, pleuritis, and splinting. The resultant hypoventilation leads to atelectasis and subsequent development of the radiographic changes of the acute chest syndrome. Prevention of hypoventilation and treatment of bone pain are important therapeutic goals.

Acute Disease↗
PubMed1995

Tumor-localizing activity of porphyrin and its affinity to LDL, transferrin.

We spectrochemically analyzed 12 Ga-Metal porphyrins (Ga-Cn-P) with different degrees of hydrophobicity, and observed a close association between the in vivo Ga-Cn-P localization in the tumor and its affinity to transferrin and LDL. Image analysis of tumors with 99m-Tc-STA-R12, a porphyrin-scintigraphic agent, revealed STA-R12 localization in the tumor tissue alone about 1 h after intravenous infusion. Our results suggest the importance of endocytosis mediated by transferrin as well as LDL that have been reported as a mechanism of the tumor-localizing activity of porphyrin.

Animals↗
PubMed1982

Internal mammary lymphoscintigraphy in the assessment of patients with ovarian carcinoma.

Radiocolloid internal mammary lymphoscintigraphy (IML) was evaluated in 364 patients with ovarian carcinoma to determine the frequency of abnormalities in post-operative patients, the association between the results of the lymphoscintigram and known clinical prognostic variables, and to establish whether IML yielded predictive information independent of these variables. Results of IML showed a correlation with established clinical prognostic features and yielded independent prognostic information. The sensitivity and specificity of IML in predicting relapse are 51% and 71% respectively, indicating that a single post-operative IML does not predict relapse or freedom from relapse with sufficient accuracy to make it a clinically useful test even though it provides an independent prediction of relapse.

Adenocarcinoma, Mucinous↗
PubMed1988

Unilateral kidney irradiation and late retreatment with cis-dichlorodiammineplatinum (II): functional measurements with 99mtechnetium-dimercaptosuccinic acid.

A rat model was used to study renal function after unilateral kidney irradiations. The left kidney was irradiated with a single dose (6-14 Gy), 2 equal sized fractions (10-16 Gy total dose) or 4 equal sized fractions (12 to 21 Gy total dose). At regular time intervals after treatment, the left kidney function was assessed with the use of 99mTc-Dimercaptosuccinic acid for a period of about 1 year. It was found that renal function declined in a dose- and time-dependent manner. The threshold dose for detecting functional impairment was 8 Gy for 1 fraction, 12 Gy for 2 fraction and 15 Gy for 4 fraction irradiations, demonstrating the sensitivity of the isotope tracer test used in these experiments. Retreatment of the rats with a single i.p. dose of 5 mg/kg cis-Dichlorodiammineplatinum (II) (cis-DDP) given at about 1 year after X ray exposure revealed an important relative decrease in the function of the irradiated compared to the unirradiated kidney. Reductions in function of 11 to 70% (depending on radiation dose and schedule) compared with control values were observed at 11 weeks after drug injection. These results demonstrate that a previously irradiated kidney is more sensitive to a subsequent treatment with cis-DDP than the contralateral hypertrophied kidney in the same animal.

Animals↗
PubMed1993

Left ventricular functional reserve in patients with syndrome X: evaluation by continuous ventricular function monitoring.

OBJECTIVES: The objective of this study was to evaluate cardiac functional reserve in patients with syndrome X. BACKGROUND: Syndrome X is characterized by stress-induced anginal pain and ST segment depression, normal findings on coronary angiography and normal left ventricular function at rest. Reduced coronary vasodilative reserve and abnormal myocardial lactate metabolism have been described in such patients. METHODS: To assess left ventricular functional reserve in patients with syndrome X, continuous radionuclide monitoring of left ventricular end-diastolic volume, end-systolic volume and ejection fraction was performed in 12 patients and 13 normal control subjects during supine bicycle ergometer exercise. RESULTS: In control subjects, end-diastolic volume increased at peak exercise from 100% to 106.5% (p < 0.01), end-systolic volume decreased from 39.1% to 22.6% (p < 0.01) and ejection fraction increased from 60.9% to 78.6% (p < 0.01). In patients with syndrome X, end-diastolic volume increased at peak exercise from 100% to 106% (p < 0.01), and end-systolic volume decreased at ST segment depression < or = 0.5 mm (the ST point) from 37% to 28.8% (p < 0.01) but increased at peak exercise to 44.7% (p < 0.01 vs. the ST point). Thus, ejection fraction increased at the ST point from 63% to 72.7% (p < 0.01) but decreased at peak exercise to 57.7% (p < 0.01 vs. the ST point and control subjects) in proportion to the degree of ST segment depression. In nine patients (75%), ejection fraction at peak exercise was lower than baseline values. All patients and control subjects showed a rapid ejection fraction increase just after exercise during the recovery period. The degree of ejection fraction "overshoot" in patients was similar to that in control subjects, but the interval from the end of exercise to the overshoot in patients was significantly longer than that in control subjects (118 vs. 65 s, p < 0.01). CONCLUSIONS: In patients with syndrome X subjected to exercise stress, left ventricular function remained normal before the onset of ST segment depression. Once ST segment depression appeared, left ventricular function deteriorated in proportion to the degree of depression, and reduced left ventricular function persisted into the recovery period. Continuous ventricular function monitoring is thus a useful predictor of reduced left ventricular functional reserve in patients with syndrome X.

Adult↗
PubMed1986

Preparation of 99mTc-tin-phosphate polyvinyl pyrollidone stabilized colloid and distribution in bone marrow.

Technetium-99m-Sn-phosphate colloid was prepared in the presence of polyvinylpyrollidone(PVP), molecular weight 44,000, for bone marrow imaging. Size of the colloidal particles, as determined by coulter counter, microphotographic and electron microscopic studies was 15-35 nm. The colloid preparation was checked for the presence of any soluble components by Sephadex G-25 chromatography. Scintigraphy in rabbits showed a high concentration of the colloid in the bone marrow. Tissue distribution studies in rabbits showed 26.7% of the injected dose at 1 h post-injection in the bone marrow collected from femoral shaft and head. Although liver and spleen showed considerable levels of activity, kidneys and compact bone did not show any uptake. The colloid cleared from the blood exponentionally with a first phase showing a relatively fast clearance while in the second phase it disappeared more slowly. Uptake of the colloid in human bone marrow was close to that in the rabbit and thus clinical evaluation is warranted.

Animals↗