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PubMed1995

Physiological responses, organ distribution, and circulation kinetics in anesthetized rats after hypovolemic exchange transfusion with technetium-99m-labeled liposome-encapsulated hemoglobin.

Physiological responses and circulation properties of liposome-encapsulated hemoglobin (LEH) labeled with technetium-99m (99mTc) were measured in rats after a 10% (170 mg/kg hemoglobin; 430 mg/kg phospholipid) or a 50% (450 mg/kg hemoglobin, 2.3 g/kg phospholipid) hypovolemic exchange transfusion (n = 5 per exchange group). Mean arterial pressure returned to baseline values (105 +/- 8 mmHg) by 90 min post-infusion for both groups. By 20 h, mean arterial pressure remained at baseline values for the 10% group, but dropped to 30 +/- 14 mmHg for the 50% group. For both groups, bradycardia was seen after the exchange period, but heart rate recovered by 30 min for the 10% group and by 90 min for the 50% group. The 99mTc-LEH remained in circulation longer for the 50% group (18.2 h half-life) than for the 10% group (2.4 h half-life). Removal of 99mTc-LEH from the bloodstream was via the liver and spleen. At 20 h, 99mTc-LEH accumulation in these organs was greater for the 10% group (liver, 36.2 +/- 1.7%; spleen, 37.5 +/- 2.5%) than for the 50% group (liver, 17.0 +/- 1.4%; spleen, 17.1 +/- 1.4%). The data show that there is less clearance of 99mTc-LEH from the bloodstream by the reticuloendothelial system after a 50% hypovolemic exchange transfusion, thus supporting the possible use of LEH as an oxygen-carrying resuscitative fluid in situations of severe blood loss.

Anesthetics↗

PubMed1996

Value of technetium-99m HMPAO-labelled leucocyte scintigraphy as an initial screening test in patients suspected of having inflammatory bowel disease.

OBJECTIVE: This study was designed to evaluate the role of technetium-99m (99mTc) hexamethyl propylene amine oxime (HMPAO)-labelled leucocyte imaging as an initial screening test in patients suspected of having inflammatory bowel disease (IBD). PATIENTS AND METHODS: Thirty-one patients in whom a final diagnosis of irritable bowel syndrome (IBS) was made (group 1) and another 33 patients with established Crohn's disease (group 2) were studied. All patients had 99mTc HMPAO-labelled leucocyte scan with imaging at 40 and 120 min. Scans with abnormal bowel uptake were considered positive and this uptake was quantified by visual grading and computer-based methods (scan score). Group 1 patients with positive 99mTc HMPAO scan underwent an indium-111 (111In)-labelled leucocyte scan (imaging at 180 min) followed by endoscopy and barium radiology as deemed necessary in order to verify the 99m Tc HMPAO result. RESULTS: Three scan patterns were seen: well localized and unequivocally positive scans at both 40 min and 2 h were obtained from 28 patients. All but one had established Crohn's disease. Diffuse bowel uptake was seen in 14 scans. Ten of these (false positive) were obtained from symptomatic patients with IBS and four (false negative) from patients with asymptomatic Crohn's disease. No bowel uptake at 40 min and 2 h was seen in 22 scans. All but two of these (who had quiescent Crohn's disease) were obtained from patients with IBS. Active Crohn's disease is associated with significantly higher scan score (mean +/- SEM, 82.1 +/- 13.6) than the false positive scans (12.5 +/- 3.1, P > or = 0.001). Patients with false positive 99mTc HMPAO scans had negative 111In scans, endoscopy and barium radiology. CONCLUSION: Bowel scanning using either 111In or 99mTc HMPAO is useful in excluding active IBD. Because of radiation dose, image quality and availability 99mTc may be preferred to 111In.

Adult↗

PubMed2006

Reproducibility of technetium-99m mercaptoacetyltriglycine clearance in patients with impaired renal function.

BACKGROUND: The aim of this study was to determine the reproducibility of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) clearance in patients with a 99mTc-MAG3 clearance below 100 ml/min/1.73 m2. METHODS: Two separate multi-sample clearance studies were performed in 16 patients at a 1 week interval. The clearances were calculated according to the open two-compartment model of Sapirstein et al., accepting the 90, 120 and 180 min samples as the last points of the biexponential curve. The clearance measurements were also performed according to the single-sample methods of Russell et al. and Bubeck using the fitted value at 44 min. RESULTS: There was no significant difference between the two clearance measurements for all five samples (P>0.05). There was a systematic increase in clearance measurements of 8.0+/-2.7% from the 180 to 120 min samples and 4.8+/-2.0% from the 120 to 90 min samples. Both single-sample methods (Bubeck and Russell et al.) gave more divergent results than multi-sample methods. The mean and standard deviation (%) of the normalized differences between two successive tests were -3.9+/-12.6, -2.4+/-13.1, -1.9+/-14.9, -4.1+/-53.5 and -13+/-82.1 for 90, 120 and 180 min samples and the Russell et al. and Bubeck methods, respectively. CONCLUSION: Single-sample methods give very poor reproducibility and accuracy and should not be used in patients with poor renal function. The reproducibility of 99mTc-MAG3 clearance using the multi-sample method (90 min) in patients with impaired renal function is 12.6%, which is similar to that in patients with good renal function and that obtained with other tubular agents. Whether this level of reproducibility is satisfactory for documenting serial changes in an individual patient with a 99mTc-MAG3 clearance below 100 ml/min/1.73 m2 depends on the expectation of the clinician.

Adult↗

PubMedDate not supplied

Comparison of electron beam computed tomography and technetium stress testing in differentiating cause of dilated versus ischemic cardiomyopathy.

OBJECTIVE: The current reference standard for differentiating between nonischemic versus ischemic cardiomyopathy (CM) is angiography. The diagnostic accuracy of nuclear stress testing and electron beam tomography (EBT) was evaluated to differentiate between nonischemic and ischemic CM, using coronary angiography as the reference standard. METHODS: A total of 56 patients who underwent technetium stress testing and coronary angiography for the evaluation of CM were enrolled. Patients then underwent EBT coronary scanning for coronary calcification (CC). RESULTS: Of the 56 patients, 34 (61%) had angiographically significant disease. Using the criteria of ischemia (reversible defect) or infarct (fixed defect) to define a patient with ischemic CM, nuclear stress testing had a sensitivity of 97% (33 of 34 patients) but a specificity of only 18% (4 of 22 patients). Using the criteria of reversible ischemia only, the specificity of nuclear stress testing improved to 50% (P < 0.001); however, the sensitivity decreased to 56%. An EBT score >0 had a sensitivity of 97% (33 of 34 patients) and a specificity of 68% (15 of 22 patients) for defining ischemia. Overall diagnostic accuracy was significantly higher with EBT as compared with nuclear stress testing in this study of patients with reduced ejection fractions (84% vs. 64%; P = 0.009). CONCLUSION: Given the high sensitivity of nuclear testing and EBT, these tests may prove to be an effective screen before angiography in patients with congestive heart failure of unclear cause.

Adult↗

PubMedDate not supplied

Comparison between contrast-enhanced magnetic resonance imaging and technetium 99m glucohepatonic acid single photon emission computed tomography with histopathologic correlation in gliomas.

OBJECTIVE: : To determine and compare the accuracy of contrast-enhanced magnetic resonance imaging (MRI) and Technetium 99m glucohepatonic acid single photon emission computed tomography (Tc-GHA SPECT) in grading of gliomas, compared with neuropathologic findings. MATERIALS AND METHODS: : The study included 20 adult patients (13 men and 7 women) with clinical/radiological suspicion of brain tumor (glial tumor) who were subjected to magnetic resonance examination and Tc-GHA brain SPECT.The lesions were evaluated by using MRI imaging score, based on 9 MRI criteria. Based on the discrimination threshold of 0.9 for mean MRI score, the gliomas were graded as low- or high-grade glioma. The Tc-GHA SPECT retention index was calculated as the ratio between delayed and early uptake ratios. Based on the discrimination threshold of 1 for Tc-GHA SPECT retention index, the gliomas were graded as low- or high-grade glioma.The diagnosis was verified by means of histopathologic examination in all patients (open surgery in 19 patients and stereotactic biopsy in 1 patient). Correlation between MRI findings/scores, SPECT scores, and histopathologic grades was done in all the patients, and comparison between MRI and Tc-GHA SPECT was made using paired Student t test and correlation coefficient. RESULTS: : The study revealed significant difference between the mean MRI scores and early uptake ratio, delayed uptake ratio, and retention index of low-grade (grades I-II) and high-grade (grades III-IV) gliomas. No statistically significant difference could be demonstrated between the abilities of contrast-enhanced MRI and Tc-GHA SPECT to allow differentiation between high- and low-grade gliomas. The accuracy of MRI (78.4%), however, was slightly higher than that of Tc-GHA SPECT (73.68%). However, Tc-GHA SPECT allowed differentiation between high-grade gliomas (between grades III and IV gliomas). CONCLUSIONS: : The accuracy of contrast-enhanced MRI in the distinction of high- and low-grade malignancy was higher than that of Tc-GHA SPECT. The performance of Tc-GHA SPECT adds little in determining tumor grade when MRI is performed. However, it may act as a useful adjunct to differentiate between grades III and IV gliomas.

Adult↗

PubMed2005

Technetium-99m diphosphonate imaging of psammocarcinoma of probable ovarian origin: case report and literature review.

Technetium-99m methylene diphosphonate (Tc-99m MDP) bone scans have long been used by clinicians to diagnose osseous metastases in patients with cancer. However, in several benign and malignant diseases, notably those characterized by extensive soft tissue calcification, Tc-99m MDP may be taken up by the tumor itself. We present a case of a stage IIIC psammoma-rich low-grade serous carcinoma of the ovary, whose identity and extent of disease were first suggested by Tc-99m MDP scintigraphy. The literature concerning this form of cancer, and the use of Tc-99m MDP bone scans to image soft tissue lesions, are reviewed.

Cystadenocarcinoma, Serous↗

PubMed2005

Technetium-99m MAG3 renal scintigraphy with demonstration of aortic dissection.

Demonstration of type B aortic dissection is rare during renal scintigraphy. The discordant radionuclide pattern of asymmetric renal flow with equivalent renal function and excretion has been previously reported in aortic dissection. However, delayed scintigraphic features of the false lumen have not been described. The author presents such a case with persistent technetium-99m MAG3 accumulation in the posterior mediastinum on postvoid planar imaging.

Aged↗

PubMed2002

Recent levels of technetium-99 in seawater at the west coast of Svalbard.

Seawater from the western coast of Svalbard was sampled in the spring and summer of 2000 to determine levels of technetium-99 (99Tc), a conservative-behaving, manmade radionuclide originating from European nuclear reprocessing plants. This paper deals with the recent levels of this radionuclide in seawater and with the link between an Arctic fjord, Kongsfjorden, and the Western Spitsbergen Current (WSC), investigated using 99Tc results. By means of the WSC, the 99Tc radionuclides ultimately reach the eastern Fram Strait west of Spitsbergen (the largest island of the Svalbard archipelago). Results from oceanographic modelling and sea ice observations indicate a direct coupling between Kongsfjorden and the area west of it. The findings in connection with new radionuclide results presented in this paper concur with these assumptions. Furthermore they indicate that the inner part of Kongsfjorden is also well linked to the WSC. Surface seawater from the central part of the WSC, sampled during a cruise with RV Polarstern in the summer of 2000, shows a higher level of 99Tc than those measured in Kongsfjorden in spring 2000. However, all levels measured in surface water are of the same order of magnitude. Data from sampling of deeper water in the WSC area provide information pertaining to the lateral distribution of 99Tc. The results, along with additional data from spring 2001, indicate that Kongsfjorden is suitable for monitoring the levels of 99Tc arriving in the European Arctic and that the sheltered setting of this fjord does not necessarily provide protection against pollution from the open sea.

Environmental Monitoring↗

PubMed1980

Administration of drugs during cardiopulmonary bypass. An analysis of the fate of a bolus injected through different routes using radio-active technetium.

This study was conducted to determine the efficiency of delivery of drugs injected as boluses by the common routes available during cardiopulmonary bypass. Radioactive technetium (99mTc) was injected in a 50 microCi bolus into the central venous line or into the arterial or venous lines of the oxygenator and its passage monitored downstream by suitable radiation detectors. When injected into the central venous line, delivery was unpredictable and at times 50% or more of the dose may not appear for 5 min. When injected into the venous line of the oxygenator an average 5% of the total dose had not reached the detector during first passage, and had completely cleared at 2 min. No significant difference was found between the different oxygenators and it is concluded that the venous line of the oxygenator is the most efficient site for the achievement of rapid action of drugs.

Cardiopulmonary Bypass↗

PubMed1976

Distribution and removal of human serum albumin-technetium 99m instilled intranasally.

The efficacy of antiviral drugs and vaccines administered intranasally may depend upon the technique of application. The distribution and time-course of removal of human serum albumin-technetium 99m (HSA-Tc 99m)-instilled intranasally were studied in eleven healthy volunteers using a gamma camera and an anterior sodium iodide scintillation detector. In 100 randomized studies material was delivered as drops in the supine position or as a spray to seated subjects. A significantly higher proportion of 'good' distributions (62 in 73 tests) was obtained with drops compared with spray (1 in 27). The volume administered was varied between 0.10 ml and 0.75 ml and the concentration of HSA was changed from 3 to 30% with no significant effect upon the distribution of time-course of removal; pertechnetate in isotonic saline was distributed and removed in a manner comparable to HSA-Tc 99m. Activity recorded by the detector showed an initial rapid fall associated with removal of most of the material from the nasal cavity, followed by a slower decline associated with the removal of material mainly from the anterior region of the nose. A multidose study confirmed that frequent administration by drops is required to maintain a high level of activity in the nasal cavity. Using this technique it should be possible to correlate measurements of antiviral efficacy and vaccines take-rates with certain characteristics of intranasal applicators; such studies may lead to the design of better devices.

Administration, Intranasal↗

PubMed1990

Technetium-99m (v) dimercaptosuccinic acid: a clinical and scintigraphic study in an animal tumour model.

Technetium-99m (99mTc) (v) dimercaptosuccinic acid (DMSA) is a new tumour-imaging agent which has been used to image head and neck squamous carcinoma. This study used an established rabbit tumour model to compare palpation versus planar scintigraphy in the detection of superficially transplanted cancers. Palpation detected 83% of tumours measuring less than 2 cm compared with 58% for scintigraphy. Overall, the sensitivity for palpation was 88% (77% specificity) compared with 50% (63% specificity) for scintigraphy.

Animals↗

PubMedDate not supplied

The use of technetium in evaluation of the male accessory glands activity.

This study was performed with the purpose to elucidate the possibility of using Technetium 99m (Tc) as a marker for the evaluation of male sex glandular activity of the rat. Tc was injected into the femoral vein of the rat and its cpm was counted. The studies have shown that 22 hours after injection of Tc the material was accumulated in the glands in much higher values than its activity in the blood (which was only 1% of its zero time activity). In the rat, the dorsolateral coagulating gland has the highest capacity of accumulating Tc. Studies on castrated rats, or rats treated with testosterone enanthate, revealed that the activity of the cells in the glands and the volume of the excretion play an important role in the evaluation of the results. Thus, the use of Tc 99m in evaluating male accessory glands activity is a new interesting approach in the study of the physiology of the male sexual glands.

Animals↗

PubMed1994

Technetium-99m DTPA renography and angiography in renal artery stenosis of varying severity.

Thirty-five hypertensive patients, consecutively studied between 1986 and 1991, were retrospectively reviewed, to compare Technetium-99m (99mTc) DTPA renal scanning for renal artery stenosis with angiography. Ten patients were on chronic angiotensin converting enzyme (ACE) inhibitor medication and 20 underwent angioplasty of their stenoses. In patients not on ACE inhibitors the renal scan specificity was 83%, sensitivity 82%, negative predictive value 89% and positive predictive value 74%. In the 10 patients on ACE inhibitors the specificity was 67% (relatively more stenoses of < 50% were reported in this group), sensitivity 100%, negative predictive value 100% and positive predictive value 60%. Low levels of function (< 10 mL/min/1.73m2) in 9 kidneys did not militate against diagnoses that correlated well with angiography. Hence, renal scanning, particularly with ACE inhibition, is efficacious in the evaluation of possible renal artery stenosis. With a mean follow-up period of 29 months after percutaneous transluminal angioplasty (PTA), four patients had clinical improvement of hypertension control. Each had pre-PTA total glomerular filtration rates (GFR) of approximately 75 mL/min/1.73m2. No improvement was detected in cases with pre-PTA total GFR of < 50 mL/min/1.73m2. This may be the level of renal function below which PTA therapy or surgery will not provide benefit.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1995

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease.

Technetium-99m hexakis-2-methoxy-isobutyl-isonitrile (99mTc sestamibi) has been used for myocardial perfusion imaging in the evaluation of coronary artery disease (CAD) since 1990. The experience of its use in an Asian population with and without previous myocardial infarction (MI), diabetes mellitus (DM), hypertension (HPT) and collateral circulation (COL) is reported. One hundred and thirty-nine patients who underwent treadmill exercise testing with 99mTc sestamibi single photon emission computed tomography (SPECT) and coronary angiogram were studied. The overall sensitivity for the detection of CAD was 91.0% and specificity was 64.7%. For patient without previous myocardial infarction, the sensitivity was 83.8% and specificity was 83.3%. Patients with COL had a higher sensitivity while those with HPT had a lower specificity. Sensitivity was higher in patients with multi-vessel disease (MVD) than single vessel disease (SVD). The overall detection for individual artery stenosis was 74.1% with a specificity of 73.1%. Amongst the three major coronary arteries, sensitivity was highest for the right coronary artery and specificity was highest for the left circumflex artery. Specificity was higher in patients without MI or COL. We found that the agreement between 99mTc sestamibi SPECT and coronary angiogram for the extent of CAD was only 52.5%. The concordance rate was higher for patients with MVD than SVD. It is concluded that 99mTc sestamibi SPECT is a sensitive and specific test for the detection of CAD and localization of disease to individual coronary arteries in our patients with some differences in the subgroups. Agreement between coronary angiogram and 99mTc sestamibi for the extent of coronary artery disease was also satisfactory.

Adult↗

PubMed1992

The value of technetium-99M renography for the detection of renal artery stenosis in patients with aortic and lower limb vascular disease.

The results of technetium renography were compared with arteriography to determine whether this is a satisfactory screening test for renal artery stenosis (RAS). Sixty-three patients were studied before aortic surgery. All were investigated by aortography and isotope renography. These tests were assessed blind and all arteriograms were graded by a single independent radiologist. Renal artery stenosis was detected by arteriography in 34 (54%) patients. Twenty-three (37%) had mild (less than 50%) stenosis, seven (11%) had moderate (50-80%) stenosis and four (6%) had severe (greater than 80%) stenosis. Of these 34 patients, only 6 (18%) were correctly diagnosed by isotope renography. None of the four with severe stenosis were identified. Isotope renography resulted in six true positives, six false positives, 23 true negatives and 28 false negatives. It was concluded that isotope renography did not fulfil the criteria for a screening test for the detection of RAS and appeared to be of no value in those patients undergoing aortic surgery in whom arteriography was not indicated.

Aged↗

PubMed1977

Imaging of acute myocardial infarction using technetium 99m labelled phosphate compounds.

Technetium 99m pyrophosphate or polyphosphate administered intravenously soon after acute myocardial infarction produces positive images of the area and extent of myocardial necrosis. Forty-four patients have been studied of whom 39 had myocardial infarction. There was good correlation of the site and extent of infarction as indicated by the scintigram with electrocardiogram and cardiac enzyme criteria.

Acute Disease↗

PubMed1995

A novel anti-seminoma monoclonal antibody (M2A) labelled with technetium-99m: potential application for radioimmunoscintigraphy.

OBJECTIVE: To study the potential usefulness of monoclonal antibody (mAb) M2A specific for seminoma to image tumour nodules in a preclinical nude mouse model. MATERIALS AND METHODS: MAb M2A was labelled with technetium-99m (99mTc) following reduction and was administered intraperitoneally to nude mice bearing subcutaneous HEY cell xenografts against which the antibody was originally raised. Biodistribution and gamma scintigraphy studies were performed 24 h after administration of 99mTc-M2A. RESULTS: Biodistribution studies showed specific targeting of 99mTc-M2A to HEY tumours in comparison with control mAb 99mTc-6E8 and 99mTc-2G3 which do not bind to HEY cells. Subcutaneous HEY cell tumours (0.5-1.0 g) were successfully imaged using gamma-scintigraphy following administration of 99mTc-M2A. CONCLUSION: The results of this study indicate the potential usefulness of 99mTc-M2A as a clinical reagent for imaging seminoma metastases.

Animals↗

PubMed1995

A reproducibility study of technetium-99m macroaggregated albumin foot perfusion imaging in patients with diabetes mellitus.

The reproducibility of Technetium-99m macroaggregated albumin (99mTc-MAA) foot perfusion imaging was assessed in 14 diabetic patients with foot ulcers. Bilateral femoral intra-arterial injections of 99mTc-MAA were administered and the feet imaged with a gamma camera. Patients returned 1 week later for a repeat study. The scans of 10 patients including one unilateral amputee were evaluated. Of these 19 limbs there were 4 failed injections (21%). The remaining 15 completed repeat studies were analysed both subjectively and semiquantitatively by 2 different observers who were blind to the patient's name and scan date. Subjectively the images of each individual were similar with reports highlighting the same abnormalities. Semiquantitatively areas of increased uptake on both images were significantly correlated for each individual (Pearson's Rho correlation coefficient = 0.96, r2 = 0.92, p < 0.0001) as were areas of poor uptake reported, reflecting decreased tissue perfusion (Pearson's Rho = 0.93, r2 = 0.86, p < 0.0001). There were no side-effects. 99mTc-MAA has proven to be a safe, generally acceptable, and reproducible technique for assessing tissue perfusion in the extremities which provides an accurate means of differentiating viable from non-viable tissue in patients with foot ulcers.

Aged↗