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Effect of a chayotte (Sechium edule) extract on the labeling of red blood cells and plasma proteins with technetium-99m: in vitro and in vivo studies.

Sechium edule (chayotte) is used as food or as medication in popular medicine. The labeling of blood elements with technetium-99m (99mTc) has been altered by drugs (synthetic and natural). Some authors have reported biological effects concerning the chayotte. We have evaluated the influence of chayotte extracts (macerated and infusion) on the labeling of blood elements with 99mTc. In vitro study, blood was incubated with the extracts, (6.25, 12.5, 25, 50 and 100% v/v). In in vivo study, the animals were treated with the extracts (100% v/v), as drinking water (15 and 60 days) and samples of blood were withdrawn. The blood samples were incubated with stannous chloride and with 99mTc. Plasma (P) and blood cells (BC) were isolated, also precipitated with trichloroacetic acid and soluble (SF) and insoluble fractions (IF) separated. There was a (p < 0.05) decrease in the radioactivity in BC, IF-BC and IF-P with the infusion (100%) and a slight decrease in the uptake of 99mTc by BC and a strong decrease in the fixation in IF-P with the macerated when the extracts were administrated in vivo (15 days). In 60 days, there was a decrease in BC (98.77 to 53.53%), in IF-BC (90.36 to 21.20%) and in IF-P (77.20 to 11.01%). In vitro study no alterations on the labeling of blood elements were found, however, we have found alterations on the fixation of 99mTc in the in vivo study, probably, due to the metabolization of chayotte capable to induce the generation of active metabolites.

Animals↗

Evaluation of the effect of mitomycin-C on the bioavailability of technetium-99m-labelled sodium pyrophosphate in mice.

We have reported that drugs alter the biodistribution of radiopharmaceuticals used in diagnostic imaging in nuclear medicine. Knowledge of such altered biodistribution is important in making diagnostic from scintigraphy. Mitomycin-C is used as component of many chemotherapeutic regimens to treat different tumors. The biological activities of mitomycin-C can be explained by its ability to inhibit deoxyribonucleic acid synthesis. Since patients on chemotherapeutic treatment can be submitted to nuclear medicine procedures, we studied the mitomycin-C effect on the bioavailability of the technetium-99m-labelled sodium pyrophosphate (9mTc-PYP) using an animal model. Mitomycin (0.45 mg) was administered by ocular plexus way Balb/c mice. One hour after the last dose, 99mTc-PYP (7.4 MBq) was administered and after 0.5 hr the animals (n = 15) were rapidly sacrificed. The organs were isolated, the radioactivity counted in a well counter and the percentage of radioactivity (%ATI) calculated. The results have shown that in the treated animals the %ATI has been decreased in spleen, thymus, heart and brain and increased in lung, liver and bone. The effect of this chemotherapeutic drug on the 99mTc-PYP biodistribution was statistically significant (Wilcoxon test, p < 0.05) and it could be explained by the metabolization or therapeutic action of mitomycin-C.

Animals↗

Study of the biodistribution of the amantadine labelled with technetium-99m in Wistar female rats.

Amantadine (AMA) has been described as dopamine stimulant and norepineprhine release, capable to block the N-methyl-D aspartate (NMDA) glutamatergic and nicotinic receptors, enhancing the sexual behavior of the male rats and inducing hypersexuality in humans. The use of technetium-99m (99mTc) can be justified for its physical and chemical properties. The aim of this study was to label and evaluate the bioavailability of the AMA labelled with 99mTc (99mTc-AMA) in Wistar female rats. The solution of 99mTc-AMA was administered by intraperitoneal way and the animals were sacrificed in CO2 chamber 10 min after the administration of the radiotracer. Various organs were removed, weighted, their radioactivity was determined using an auto-gamma counter and the results were expressed as the percentage of the injected activity per gram of tissue (%ATI/g). In the control group only Na99mTcO4 was administered. The analysis of results shows that the highest uptakes 99mTc-AMA treated group were: ovary (7.11 +/- 1.43), spleen (3.54 +/- 1.05), thyroid (2.67 +/- 0.15), stomach (1.56 +/- 1.10), duodenum (0.87 +/- 0.52), muscular tissue (0.57 +/- 0.06), liver (0.52 +/- 0.25), and at control group: thyroid (16.45 +/- 2.57), ovary (1.28 +/- 0.12), liver (1.10 +/- 0.04), spleen (0.57 +/- 0.07) and muscular tissue (0.26 +/- 0.03). The results obtained suggest that 99mTc-AMA may be used to study the bioavailability of amantadine and evaluate its effect in sexual behavior in female rats.

Amantadine↗

Evaluation of the cytotoxic and mutagenic potentiality of technetium-99m in Escherichi coli.

Since technetium-99m (99mTc) was introduced in medical research it has become one of the most employed radionuclides in nuclear medicine. 99mTc is ideal for routine use on the labeling of different radiopharmaceuticals due to its favorable characteristics. However, some biological effects have been described. These effects may be related to internal conversion electron and/or Auger electron emissions from 99mTc decay that present high linear energy transfer and can generate reactive oxygen species (ROS) in the medium. We evaluated in Escherichia coli K12S and Salmonella typhimurium TA102, both proficient in DNA repair, contribution of those decay emissions on the cytotoxicity induced by 99mTc, both either by generating lesions on DNA or by inducing alterations at membrane. We also studied the genotoxic and/or mutagenic potentiality of 99mTc, in Salmonella typhimurium, using the Ames test. The results showed that: i/ 99mTc is cytotoxic to the Escherichia coli K12S strains; ii/ this effect is related to the electrons (Auger and internal conversion) emissions, and iii/ the 99mTc is not mutagenic and/or genotoxic, when measured by Ames test.

Electrons↗

Limitations of technetium 99m sestamibi scintigraphic localization for primary hyperparathyroidism associated with multiglandular disease.

Successful surgical treatment of primary hyperparathyroidism requires the localization and excision of the parathyroid tissue responsible for excessive parathyroid hormone secretion while ensuring that the patient will have sufficient endogenous parathyroid hormone production to maintain eucalcemia. In selecting patients with primary hyperparathyroidism for unilateral parathyroidectomy the surgeon should be able to diagnose multiglandular disease either preoperatively or intraoperatively. We performed a retrospective review of 123 patients who underwent surgical treatment for primary hyperparathyroidism to determine the potential feasibility of selecting patients for minimally invasive surgery based on preoperative imaging studies. All patients were studied preoperatively with 99m technetium-sestamibi scintigraphy. High-resolution ultrasonography was performed in 119 of these patients. All patients except one underwent bilateral cervical exploration. A patient with an intrathoracic adenoma was successfully diagnosed by scintigraphy thereby allowing treatment by a limited thoracotomy. One hundred eight patients had solitary adenomas and 15 had multiglandular disease. In none of the patients with bilateral multiglandular disease were all abnormal glands localized preoperatively. Patients in our study with primary hyperparathyroidism and multiglandular disease were underdiagnosed by preoperative imaging. A minimally invasive approach based solely on preoperative imaging studies may result in treatment failure in patients with multiglandular involvement.

Adenoma↗

The false negative technetium-99m-sestamibi scan in patients with primary hyperparathyroidism: correlation with clinical factors and operative findings.

False negative (FN) results limit the efficacy of technetium-99m-sestamibi scanning for parathyroid localization. We determined the incidence of FN results and attempted to correlate it with clinical and operative findings. One hundred forty-six patients underwent parathyroidectomy; 89 had primary hyperparathyroidism (76 single adenoma and 13 multiglandular disease) and underwent sestamibi scanning. The false negative rate was 22 per cent with an overall sensitivity of 77 per cent and a positive predictive value of 99 per cent. Patients with single adenomas were more likely to have a true positive scan than those with multiglandular disease [83% vs 38%; odds ratio (OR) = 7.754, 95% confidence interval (CI) = 2.184-27.524; P < or = 0.0001]. Inferior adenomas (90% vs 59%; OR = 6.261, 95% CI = 2.037-19.243; P < or = 0.0001) and larger adenomas (1422.3 +/- 1576.2 vs 474.6 +/- 193.2 g; P < or = 0.0001) were more likely to be detected by sestamibi imaging. Patients with normal preoperative calcium levels were more likely to have an FN sestamibi scan. Sestamibi parathyroid imaging is limited by a 22 per cent FN rate and is less accurate for detecting abnormal parathyroid tissue in patients with small adenomas, multiglandular disease, superior adenomas, or preoperative normocalcemia.

Adenoma↗

Usefulness of technetium-99m methoxyisobutylisonitrile liver single photon emission computed tomography to detect hepatocellular carcinoma.

Technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) has been shown to be useful in identifying several types of tumors, such as breast, lung and thyroid cancers. The usefulness of Tc-99m MIBI liver imaging in detecting hepatocellular carcinoma (HCC) is still controversial. In this study, 22 patients with HCC performed Tc-99m MIBI liver single photon emission computed tomography (SPECT). Twenty of 22 patients (90.9%) showed negative liver SPECT findings without significant Tc-99m MIBI uptake in HCC, and only 2 patients (9.1%) showed positive liver SPECT findings with significant Tc-99m MIBI uptake in HCC. In addition, no significant correlation between liver SPECT findings with sex, age, alpha feto-protein serum level, HCC differentiation, and virus hepatitis status was found. We concluded that Tc-99m MIBI liver SPECT is not a sensitive tool to detect HCC.

Adult↗

The usefulness of technetium-99m hexamethylpropyleneamineoxide labeled white blood cell abdomen scan to differentiate periappendiceal abscess from acute appendicitis--a preliminary report.

BACKGROUND/AIMS: The purpose of this study is to assess the usefulness of Tc-HMPAO (technetium-99m hexamethylpropyleneamineoxide) labeled white blood cells abdomen scan to differentiate acute appendicitis from periappendiceal abscess. METHODOLOGY: Forty-five patients with atypical symptoms and signs of appendicitis were included in this preliminary study. At 4 hours after an intravenous injection of Tc-HMPAO labeled white blood cells, static images over the anterior abdomen were obtained using a gamma camera. Two regions of interest were selected, one was over the lumbar spine and the other was over the appendiceal area. The mean count ratio of the appendiceal area over the mean pixel count of the lumbar spine was calculated. Sixteen patients were diagnosed with acute appendicitis and 19 patients with periappendiceal abscess by final operative findings. Meanwhile, the other 10 patients with acute abdomen but with no appendicitis served as controls. RESULTS: The mean count ratio of controls, acute appendicitis and periappendiceal abscess was 0.65 +/- 0.05, 0.82 +/- 0.07, and 1.25 +/- 0.11, respectively. If the mean count ratio > or = 1.00 was defined as the cutoff value to diagnose periappendiceal abscess, the specificity and the positive predictive value was 100%. CONCLUSIONS: We concluded that Tc-HMPAO white blood cells abdomen scan should be a potential tool to differentiate periappendiceal abscess from acute appendicitis.

Abdominal Abscess↗

Comparison between technetium-99m hexamethylpropyleneamineoxide labeled white blood cell abdomen scan and abdominal sonography to detect appendicitis in children with an atypical clinical presentation.

BACKGROUND/AIMS: Diagnosing acute appendicitis in children with equivocal signs and symptoms is usually difficult. The usual approach to the patient is hospital observation and frequent reexamination. However, many surgeons are reluctant to delay surgery because of the risk of perforation and a negative laparotomy. The aim of this study is to assess and compare the value of the Tc-99m HMPAO (technetium-99m hexamethylpropyleneamineoxide) labeled white blood cell abdomen scan and abdominal sonography in the diagnosis of acute appendicitis in children with an atypical clinical presentation. METHODOLOGY: Forty children with acute abdomen and possible acute appendicitis but atypical findings were included in this study. After an intravenous injection of Tc-99m HMPAO white blood cells, serial anterior abdomen scans at 30 min, 60 min, 120 min and 240 min were obtained using a gamma camera. Meanwhile, at the point of maximal tenderness, abdominal sonography was performed with a graded compression technique for both longitudinal and transverse images. RESULTS: Thirty-three children received operation for surgical and pathological diagnoses. The other 17 children did not receive operation but follow-up of at least a one-month period. The overall sensitivity, specificity, and accuracy of Tc-99m HMPAO white blood cell scan to diagnose acute appendicitis in children with atypical findings is 96.7%, 80.0%, and 90.0%, respectively. The overall sensitivity, specificity, and accuracy for abdominal sonography is 86.6%, 90.0%, and 88.0%, respectively. CONCLUSIONS: The Tc-99m HMPAO white blood cell abdomen scan provides a more sensitive and accurate method for the diagnosis of appendicitis in children with atypical clinical presentation when compared with abdominal sonography.

Abdomen↗

Samarium-153 and technetium-99m-labeled monoclonal antibodies in angiogenesis for tumor visualization and inhibition.

BACKGROUND: Angiogenesis is the development of new blood vessels from pre-existing ones. Vascular endothelial growth factor (VEGF) is one of the most important angiogenic activators. Our studies are focused on the detection of VEGF by use of radiolabeled anti-endothelial monoclonal antibodies, which have the ability to localize in newly-formed vasculature of a cancerous origin. MATERIALS AND METHODS: The anti-endothelial monoclonal antibody VG76e was labeled with Samarium-153 and Technetium-99m. Biodistribution of the radiolabeled species was assessed in normal female Swiss mice, while tumor uptake was also evaluated. RESULTS: VG76e was labeled with 99mTc and 153Sm, resulting in a single product with a labeling yield of over 95%. Biodistribution studies showed non-specific uptake in any organ, with elimination via the hepatobiliary system. Finally, satisfactory tumor uptake was observed for both radiolabeled derivatives. CONCLUSION: Monoclonal antibodies raised against epithelial growth factors or their receptors, when labeled with appropriate radionuclides, may be a useful tool for early tumor detection and eventually for therapy.

Animals↗

Usefulness of technetium-99m hexamethylpropylene amine oxime lung scan to detect sub-clinical lung injury of patients with breast cancer after chemotherapy.

We investigated the sub-clinical lung injury in patients with breast cancer after chemotherapy by technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) lung scan. Fifty patients who underwent surgical resection for breast cancers were divided into two groups, those who received a combination of adjuvant chemotherapy and those who did not. Group 1 consisted of 25 patients who received adjuvant chemotherapy and group 2 consisted of 25 patients who did not receive adjuvant chemotherapy. Tc-99m HMPAO lung scan was performed in each patient and the degree of pulmonary vascular endothelium damage was represented as lung/liver uptake ratios (L/L ratio). None of the 50 patients had positive plain chest radiograph (CXR) and pulmonary function test (PFT) findings. The results showed a significantly higher L/L ratio in the group 1 patients (0.57 +/- 0.13) than in the group 2 patients (0.32 +/- 0.05). We conclude that chemotherapeutic drugs may result in pulmonary vascular endothelium damage and that Tc-99m HMPAO lung scan has the potential to be a sensitive, objective and non-invasive method to detect sub-clinical lung injury of patients with breast cancers after chemotherapy.

Adult↗

The effect of phenobarbital on the accuracy of technetium-99m diisopropyl iminodiacetic acid hepatobiliary scintigraphy in differentiating biliary atresia from neonatal hepatitis syndrome.

Biliary atresia (BA) and neonatal hepatitis syndrome (NHS) are major causes of cholestatic jaundice in infancy. Technetium-99m diisopropyl iminodiacetic acid hepatobiliary scintigraphy (99mTc-DISIDA scan) is widely used in the differentiation of these two entities. The objective of this study was to evaluate the effect of phenobarbital premedication on the accuracy of 99mTc-DISIDA scan. Ninety-five cholestatic infants (38 females and 57 males) with an age range of 2 weeks to 4 months (mean 2.1 mo) who underwent 99mTc-DISIDA scan testing were retrospectively reviewed. The patients were divided into 3 groups according to the history of phenobarbital administration prior to 99mTc-DISIDA scan examination. Group 1 (n = 48), group 2 (n = 29), and group 3 (n = 18) received phenobarbital at the dosage of 5 mg/kg/day for at least 5 days, less than 5 mg/kg/day or less than 5 days, and no premedication, respectively. The accuracy of 99mTc-DISIDA scan in differentiating BA from NHS in group 1, 2, and 3 was 72.92 per cent, 89.66 per cent, and 100 per cent, respectively. No significant difference was seen between the patients who received and did not receive phenobarbital in terms of age at presentation, age at onset of jaundice, and liver function tests. In conclusion, phenobarbital therapy may not be necessary prior to 99mTc-DISIDA scan examination in the evaluation of cholestatic infants and thus a delay in diagnosis and surgical therapy of BA can be avoided.

Biliary Atresia↗

Technetium 99m pentavalent dimercaptosuccinic acid and thallium 201 in detecting recurrent medullary carcinoma of the thyroid.

To compare the effectiveness of thallium chloride 201 and technetium 99m pentavalent dimercaptosuccinic acid in evaluating medullary carcinoma of the thyroid (MCT), eight patients with a history of MCT underwent imaging with both radiopharmaceuticals. Thallium 201 consistently gave superior images, as well as providing one less false-negative scan. Positive scans were obtained in patients with elevation of basal calcitonin levels to more than 1,000 ng/L. All of the patients with positive scans had clinical evidence of local recurrence. Improved imaging with thallium 201 was obtained by early scanning.

Calcitonin↗

[Scintigraphic imaging of head and neck cancers with 99m technetium (v) dimercaptosuccinic acid. A prospective clinical study].

In patients with cervical metastases conventional examination by ultrasound, CT or MRI imaging often fails to identify an unknown primary tumor. Also the retrieval of a recurrent malignancy may be difficult. Scintigraphy, utilizing technetium-99m (v) dimercaptosuccinic acid was chosen for a prospective study in 17 patients to evaluate its properties for imaging metastasizing squamous cell carcinoma of the head and neck. Scintigraphic findings were correlated with the results of clinical examination and conventional imaging techniques. In all cases the primary tumor revealed good uptake of 99mTc(v)DMSA. Manifest cervical metastases could only be imaged in some cases. In future, therefore, 99mTc(v)DMSA scanning may be used for the detection of unknown primary tumors. However, it does not appear helpful in the evaluation of cervical nodes.

Carcinoma, Squamous Cell↗

Localization of obscure gastrointestinal bleeding by technetium 99m-labeled red blood cell scintigraphy.

When a bleeding source from the gastrointestinal (GI) tract cannot be identified with conventional diagnostic studies, it is known as GI bleeding of an obscure origin. In the past three years, in vivo Technetium 99m-labeled red blood cell scintigraphy (RBC scan) has been added to our armamentarium for the diagnosis of obscure GI bleeding. Out of a total of 26 cases, the bleeders could be detected in 12 or 46.2% by RBC scan. The time required ranged from 15 minutes to 24 hours (median, one hour). In 14 patients with active bleeding during the scan period, 11 had positive scans (sensitivity, 78.6%). In 12 patients with inactive bleeding, 11 had negative scans (specificity, 91.7%). Angiography was conducted in nine cases, with all showing negative findings; however, six of them had a positive focus by RBC scan. Laparotomy was performed in seven scan-positive patients, and in three scan-negative patients because of a positive Meckel's scan (two cases) or recurrent bleeding (one case). Of the 12 scan-positive patients, incorrect localization was noted in two patients due to rapid transit of the labeled RBC in the small bowel. False localization could be prevented by shortening the sequential imaging interval. It is concluded that an RBC scan is a very sensitive and safe tool for detection of GI bleeding of an intermittent nature, because the bleeder can be monitored for 24 hours after a single injection. It can be used as a preangiographic screening test and to guide the surgeon in surgical planning or decision-making.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Prospective validation of a single sample technique to determine technetium-99m-MAG3 clearance.

Technetium-99m-MAG3 clearance is proportional to OIH clearance and can be used directly as a measure of renal function. Multiple plasma sample, two-compartment clearance data from three studies were recently pooled to develop a single-sample regression equation for determining the clearance of 99mTc-MAG3. To test this published equation, a prospective study was conducted in 34 patients with a wide range of renal function. Multiple plasma samples were obtained from 9 to 60 min following the bolus injection of 99mTc-MAG3 and the clearances were calculated based on a single injection, two-compartment model. Clearances were also calculated using a single 43-min plasma sample and the published regression equation. There was an excellent correlation (r = 0.976) between the two clearances; the slope of the regression line was 1.01 with an intercept of -26.6; the standard error of the estimate was 24 ml/min. In conclusion, the current regression equation provides a good estimate of 99mTc-MAG3 clearance.

Chromatography, High Pressure Liquid↗

Intravenous dipyridamole technetium-99m MMI myocardial perfusion scintigraphy for detection of coronary artery disease.

To evaluate the efficacy of stress technetium-99m MMI (N-2-methoxy-2-methyl propyl isonitrile) myocardial perfusion scintigraphy (Tc-99m MMI) using intravenous dipyridamole for detection of coronary artery disease (CAD), we collected 66 cases (53 men, 13 women, aged 40-79 years old) between Sept. 1990 and Oct. 1991. The cases were divided into two groups: group I involving 44 patients received coronary arteriography (CAG) examination without previous percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass graft (CABG); group II embracing 22 patients received no CAG examination but all were suffering from old myocardial infarction (MI) evidenced by history and electrocardiography (ECG). All cases underwent Tc-99m MMI planar and single photon emission computed tomography (SPECT) both on intravenous dipyridamole stress and separate day rest tests. Of the 44 group I patients receiving both Tc-99m MMI and CAG, 35 (79.5%) were positive and 7 (16%) were negative by both tests and another 2 (4.5%) were positive by CAG only. Of those positive by both tests, 21 (60%) suffered from identical coronary arterial involvement, including 13 one-vessel disease, 5 double-vessel disease and 3 triple-vessel disease. Of group II patients, 14 suffered from old inferior wall (IW) MI, 6 from old anterior or anteroseptal wall (AW) MI, 1 from old lateral wall (LW) MI and another 1 from combined old anterior and lateral wall (ALW) MI by ECG. Of the 14 patients with IWMI by ECG, all suffered from right coronary artery (RCA) disease but 7 (50%) of them from multivessel disease (MVD) by Tc-99m MMI. 5 of the 6 patients with AWMI by ECG suffered from left anterior descending coronary artery (LAD) disease, but 3 of them from MVD by Tc-99m MMI. Both patients with LWMI and ALWMI by ECG suffered from triple-vessel disease by Tc-99m MMI. The sensitivity of Tc-99m MMI in detecting CAD in group I was 95%, the specificity was 100%. The sensitivity for detection of individual coronary artery disease in LAD, left circumflex coronary artery (LCX) and RCA was 96%, 45% and 89% in this order and the respective specificity was 94%, 100% and 88%. In group II the sensitivity was 95%. The overall sensitivity of intravenous dipyridamole Tc-99m MMI for detection of CAD in groups I and II was 95%; specificity was 100% and accuracy was 95%. In conclusion, stress Tc-99m MMI using intravenous dipyridamole is a valuable method for evaluation and detection of CAD.

Adult↗

Dual-isotope brain SPECT imaging with technetium-99m and iodine-123: clinical validation using xenon-133 SPECT.

Our phantom studies indicate that the energy resolution (9.7% FWHM) of a new three-headed single-photon tomograph (PRISM-3000) separates the distribution of 99mTc from 123I for 10% asymmetric or 15% or 10% centered 99mTc windows when combined with a 10% asymmetric 123I window. This technique is now applied to the simultaneous measurement of resting rCBF and changes induced by vasodilation (1 g acetazolamide) in 10 subjects with cerebrovascular disease. Resting and vasodilated 133Xe SPECT images were obtained first. Within 48 hr, 99mTc HMPAO was given at rest, acetazolamide injected, and after 20 min either [123I] IMP or [123I] HIPDM was administered. Subjects were scanned for 99mTc and 123I simultaneously using 10% asymmetric windows. Regression analyses demonstrated a linear relationship between 133Xe SPECT and dual-isotope SPECT measurements of lesion-to-cerebellum ratios in baseline (r = 0.92), vasodilated (r = 0.86) and rest-minus-vasodilated data (r = 0.85). Technetium-99m and 123I images obtained through dual-isotope imaging are by definition in perfect anatomic registration.

Acetazolamide↗