PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “TECHNETIUM”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1998

Imaging of cerebral blood flow with technetium-99m-HMPAO and technetium-99m-ECD: a comparison.

UNLABELLED: Because 99mTc-HMPAO and 99mTc-ECD are both used for SPECT imaging of cerebral blood flow, the question arises whether there are any differences in their respective regional cerebral distribution. For that purpose, visual and semiquantitative comparisons between 99mTc-HMPAO and 99mTc-ECD studies were performed. METHODS: Seventeen patients (4 women; 13 men; age 45-89 yr; mean age 71 yr) with various neurological diseases, except acute/subacute stroke, were investigated twice with 99mTc-HMPAO and 99mTc-ECD using a triple-headed rotating SPECT camera. After image reorientation, the two studies were evaluated visually. Seventy regions of interest (ROIs) were drawn manually and the same set of ROIs was applied in both studies. Regional indices (RI) normalized to individual brain values were calculated and first compared between two random patient groups. Second, for all patients, RI for 70 and later for 27 regions (gained after summing values of corresponding regions in different brain slices) were compared by using a paired Student's t-test applying Bonferroni's correction. RESULTS: Visual evaluation demonstrated relatively high 99mTc-ECD uptake in occipital and comparatively low uptake in mediotemporal regions. Calculation of RI revealed significantly higher values in the right cerebellum, brainstem, mediotemporal regions, right basal ganglia and the thalamus in the 99mTc-HMPAO SPECT studies and higher values in the occipital, supratemporal/inferior parietal and parietal cortex in the 99mTc-ECD SPECT studies, respectively. CONCLUSION: Significant differences in regional tracer distribution between 99mTc-HMPAO and 99mTc-ECD could be detected, probably caused by different tracer kinetics. The results indicate that direct comparisons of studies performed with 99mTc-HMPAO and 99mTc-ECD are not possible and the use of either tracer can be favorable in different clinical questions.

Aged↗
PubMedDate not supplied

Comparison of imaging properties of technetium 99m Q12 and technetium 99m Q3 in humans.

BACKGROUND: This study was a direct comparison of the imaging characteristics of 99mTc-labeled Q12 (99mTc-Q12) and 99mTc-labeled Q3 (99mTc-Q3) in the same patients. METHODS AND RESULTS: In 10 patients with known angiographic coronary artery anatomy, 99mTc-Q12 and 99mTc-Q3 myocardial imaging were performed. Tomographic myocardial imaging was started 15 minutes after tracer injection at rest and with treadmill exercise. Ratios of heart-to-lung and heart-to-liver activity were calculated from the anterior plane projections of the tomograms at 20 minutes after tracer injection. The presence or absence of angiographic coronary artery disease was correctly determined from 99mTc-Q12 images in 10 of 10 patients with 99mTc-Q12 and in 9 of 10 patients with 99mTc-Q3. The presence or absence of a greater than 50% stenosis in an individual coronary vessel was correctly predicted for 26 of 30 vessels with 99mTc-Q12 (87%) and in 27 of 30 vessels with 99mTc-Q3 (90%, p = NS vs 99mTc-Q12). Mean heart-to-lung activity ratio at rest was 1.50 for 99mTc-Q12 and 1.93 for 99mTc-Q3 (p < 0.01). Mean heart-to-liver activity ratio at rest for 99mTc-Q12 was 0.78 versus 0.54 for 99mTc-Q3 (p < 0.0001). CONCLUSIONS: In 10 patients with chest pain and angiographically defined coronary anatomy, 99mTc-Q12 and 99mTc-Q3 provided similar detection of coronary artery stenoses. At 20 minutes after tracer injection, heart-to-liver activity ratios were more favorable for 99mTc-Q12 than for 99mTc-Q3, but 99mTc-Q3 resulted in a more favorable ratio of heart-to-lung activity.

Adult↗
PubMedDate not supplied

Synthesis, characterization, and biological evaluation of technetium(III) complexes with tridentate/bidentate S,E,S/P,S coordination (E = O, N(CH(3)), S): a novel approach to robust technetium chelates suitable for linking the metal to biomolecules.

A novel type of mixed-ligand Tc(III) complexes, [Tc(SCH(2)CH(2)-E-CH(2)CH(2)S)(PR(2)S)] (E = S, N(CH(3)); PR(2)S = phosphinothiolate with R = aryl, alkyl) is described. These "3+2"-coordinated complexes can be prepared in a two-step reduction/substitution procedure via the appropriate chloro-containing oxotechnetium(V) complex [TcO(SES)Cl] [E=S, N(CH(3)]. Tc(III) compounds have been fully characterized both in solid and solution states and found to adopt the trigonal-bipyramidal coordination geometry. The equatorial trigonal plane is formed by three thiolate sulfur atoms, whereas the phosphorus of the bidentate P,S ligand and the neutral donor of the tridentate chelator occupy the apical positions. The (99)Tc(III) complexes have been proven to be identical with the (99m)Tc agents prepared at the no-carrier-added level by comparison of the corresponding UV/vis and radiometric HPLC profiles. Challenge experiments with glutathione clearly indicate that this tripeptide has no effect on the stability of the (99m)Tc complexes in solutions. Biodistribution studies have been carried out in rats at 5 and 120 min postinjection. The substituents at the bidentate P,S ligand significantly influence the biodistribution pattern. Remarkable differences are observed especially in brain, blood, lungs, and liver. All the complexes are able to penetrate the blood-brain barrier of rats and showed a relatively fast washout from the brain.

Animals↗
PubMed1997

Synthesis and Characterization of Rhenium(III) and Technetium(III) Organohydrazide Chelate Complexes. Reactions of 2-Hydrazinopyridine with Complexes of Rhenium and Technetium.

The organohydrazide chelate complexes M(III)(NNpy)(PPh(3))(2)Cl(2) (1, 3) (M = Re, Tc) have been synthesized using the organohydrazine 2-hydrazinopyridine. The chelated organohydrazide is a diazenido(1-) ligand that forms a five-membered ring with the metal center. An X-ray structural analysis of 1 indicates that there is a delocalized pi-system formed by the chelate ring. These octahedral, d(4) metal complexes have diamagnetic (1)H NMR spectra. Complex 1, C(41.50)H(34)Cl(2)N(3)O(0.5)P(2)Re, crystallizes in the triclinic space group P&onemacr; with a = 10.5549(7) Å, b = 12.2699(8) Å, c = 16.8206(12) Å, alpha = 105.9050(10) degrees, beta = 95.8930(10) degrees, gamma = 111.0100(10) degrees, V = 1906.1(2) Å(3), Z = 2, and R = 0.0650 based on 5268 unique reflections. The FABMS+ in (p-nitrobenzyl alcohol) of 3 reveals a parent ion peak at m/z 799.2. The complex [Re(HNNpy)(NNpy)(PMe(2)Ph)(2)Cl](+)[Cl](-) (2) contains a chelated, neutral organodiazene ligand and a linear, diazenido(1-) ligand. The X-ray structural analysis of 2, C(26)H(30)Cl(2)N(6)P(2)Re, indicates a delocalized pi-system formed by the chelate ring. The (1)H NMR spectrum of 2 is not paramagnetically shifted. Complex 2 crystallizes in the orthorhombic space group Pna2(1) with a = 17.383(4) Å, b = 13.967(3) Å, c = 12.002(2) Å, V = 2913.9(10) Å(3), Z = 4, and R = 0.0384 based on 3083 unique reflections.

Journal Article↗
PubMed1997

Assessment of left ventricular volume using ECG-gated SPECT with technetium-99m-MIBI and technetium-99m-tetrofosmin.

UNLABELLED: We evaluated ECG-gated SPECT (g-SPECT) in the measurement of absolute left ventricular (LV) volume by comparing it with left ventriculography (LVG) and with cine-MRI. METHODS: Projection data from 31 patients were acquired with a three-headed SPECT system in 12 min using a 64 x 64 matrix with 1.5 zoom (1 pixel = 4.27 mm). The R-R interval from simultaneously acquired ECG was divided into eight frames. The end-diastolic and end-systolic volumes (EDV; ESV) and LV mass were assessed by an area-length method with manual delineation of the epi- and endocardial LV borders using midventricular vertical and horizontal long-axis images. The stroke volume, LVEF and cardiac output (CO) were generated from the EDV, ESV and heart rate during the study. The g-SPECT LV values were compared with those of LVG (25 patients) and cine-MRI (18 patients). RESULTS: The g-SPECT values correlated well with those from LVG (r = 0.83 to 0.92; p < 0.001) and cine-MRI (r = 0.76 to 0.99; p < 0.001). The g-SPECT technique provides an assessment of LV volumes (EDV, ESV, stroke volume, LVEF, CO, LV mass). CONCLUSION: Despite potential problems that may cause inaccuracy and require improvements such as an accurate and reproducible automatic edge detection algorithm, g-SPECT has clinical utility in assessing global LV volumes and function.

Adult↗
PubMed1994

Positron emission tomography detects evidence of viability in rest technetium-99m sestamibi defects.

OBJECTIVES: The purpose of this study was to determine the relative value of single-photon emission computed tomographic (SPECT) imaging at rest using technetium-99m methoxyisobutyl isonitrile (technetium-99m sestamibi) with positron emission tomography for detection of viable myocardium. BACKGROUND: Recent studies comparing positron emission tomography and thallium-201 reinjection with rest technetium-99m sestamibi imaging have suggested that the latter technique underestimates myocardial viability. METHODS: Twenty patients with a previous myocardial infarction underwent rest technetium-99m sestamibi imaging and positron emission tomography using fluorine (F)-18 deoxyglucose and nitrogen (N)-13 ammonia. In each patient, circumferential profile analysis was used to determine technetium-99m sestamibi, F-18 deoxyglucose and N-13 ammonia activity (expressed as percent of peak activity) in nine cardiac segments and in the perfusion defect defined by the area having technetium-99m sestamibi activity < 60%. Technetium-99m sestamibi defects were graded as moderate (50% to 59% of peak activity) and severe (< 50% of peak activity). Estimates of perfusion defect size were compared between technetium-99m sestamibi and N-13 ammonia. RESULTS: Sixteen (53%) of 30 segments with moderate defects and 16 (47%) of 34 segments with severe defects had > or = 60% F-18 deoxyglucose activity considered indicative of viability. Fluorine-18 deoxyglucose evidence of viability was still present in 50% of segments with technetium-99m sestamibi activity < 40%. There was no significant difference in the mean (+/- SD) technetium-99m sestamibi activity in segments with viable (40 +/- 7%) and nonviable segments (49 +/- 7%, p = 0.84). Of the 18 patients who had adequate F-18 deoxyglucose studies, the area of the technetium-99m sestamibi defect was viable in 5 (28%). In 16 patients (80%), perfusion defect size determined by technetium-99m sestamibi exceeded that measured by N-13 ammonia. The difference in defect size between technetium-99m sestamibi and N-13 ammonia was significantly greater in patients with viable (21 +/- 9%) versus nonviable segments (7 +/- 9%, p = 0.007). CONCLUSIONS: Moderate and severe rest technetium-99m sestamibi defects frequently have metabolic evidence of viability. Technetium-99m sestamibi SPECT yields larger perfusion defects than does N-13 ammonia positron emission tomography when the same threshold values are used.

Adult↗
PubMed1996

Technetium Tc 99m rapidly crosses the ovine placenta and intramembranous pathway.

OBJECTIVE: This study examined the movement of the soluble ion technetium Tc 99m across the ovine placenta and intramembranous pathway. STUDY DESIGN: Nineteen fetal sheep at 131 +/- 1 (SE) days' gestation were studied. After a 1-hour control period technetium Tc 99m was injected into either a fetal vein (n = 7), the amniotic cavity (n = 5), or a maternal vein (n = 5). Maternal and fetal blood, fetal urine, and amniotic and allantoic fluid were sampled during the control period and for 8 hours after the injection. Fetal urine was drained externally throughout the experiment. In five animals technetium Tc 99m was injected intraamniotically after the fetus was killed with air emboli and sampled as described. RESULTS: Intrafetally injected technetium Tc 99m rapidly crossed the placenta; then it entered and was concentrated in the amniotic cavity. Intraamniotically injected technetium Tc 99m rapidly entered into the fetal circulation. The maternally injected technetium Tc 99m rapidly crossed the placenta into the fetus, suggesting a half-time for placental exchange of < 50 minutes. The technetium Tc 99m injected into the dead fetus group demonstrated significantly less maternal absorption than in the live fetus group. CONCLUSIONS: The soluble ion technetium Tc 99m demonstrated a much more rapid movement in both directions across the ovine placenta then previously demonstrated for the smaller ion sodium. Technetium Tc 99m rapidly crossed the intramembranous pathway bidirectionally, suggesting a high permeability of the intramembranous pathway. Minimal maternal absorption of technetium Tc 99m in the dead fetus group suggests little transmembranous absorption by the mother.

Animals↗
PubMed1994

Validation of global and segmental left ventricular contractile function using gated planar technetium-99m sestamibi myocardial perfusion imaging.

OBJECTIVES: The purpose of this study was to test the hypothesis that segmental wall motion analysis determined from gated planar technetium-99m sestamibi myocardial imaging is reproducible and agrees well with echocardiographic data. BACKGROUND: Technetium-99m sestamibi is a new radiopharmaceutical recently approved for myocardial perfusion imaging. Its advantages include a dosimetry that allows use of a dose 10 to 15 times higher than that of thallium-201. As a result, myocardial counts are markedly improved and images can be collected in a gated mode to potentially allow assessment of global and segmental ventricular function. However, the reproducibility and accuracy of technetium-99m sestamibi imaging for measurement of global and segmental left ventricular function have not been evaluated or compared with those of a standard ventricular function technique, such as echocardiography. METHODS: We studied 136 patients referred for clinical technetium-99m sestamibi imaging. One-day rest-stress planar technetium-99m sestamibi protocols were used, gating the stress images. After technetium-99m sestamibi imaging, all patients had standard rest two-dimensional echocardiography. Global and segmental technetium-99m sestamibi and echocardiographic left ventricular contraction was graded qualitatively as normal or abnormal using a four-point grading system. RESULTS: Interobserver and intraobserver agreement was extremely high for global and segmental technetium-99m sestamibi wall motion analysis, with absolute agreements ranging from 0.92 to 1.00 and corresponding kappa values of 0.74 to 1.00 (p < 0.00001). Agreement with global and segmental echocardiographic wall motion was similarly very high, with absolute agreements ranging from 0.93 to 1.00 and corresponding kappa values of 0.75 to 1.00 (p < 0.00001). CONCLUSIONS: Gated technetium-99m sestamibi cardiac imaging provides information with regard to rest global and segmental left ventricular systolic function that is highly reproducible and agrees very well with results of two-dimensional echocardiography.

Adult↗
PubMed2006

Technetium Tc 99m sestamibi sensitivity in oxyphil cell-dominant parathyroid adenomas.

OBJECTIVE: A subset of parathyroid adenomas contains a relative overabundance of oxyphil cells that are capable of greater technetium Tc 99m sestamibi tracer uptake and retention than other cell types. We examined whether the presence of oxyphil cells augments the sensitivity of technetium Tc 99m sestamibi preoperative localization and whether the histologic findings of a lesion could be predicted based on the adenoma mass and serum calcium and parathyroid hormone levels. DESIGN: Retrospective, single-blinded comparison of technetium Tc 99m sensitivity rates, lesion mass, and preoperative serum calcium and parathyroid hormone values of patients with chief and mixed cell-dominant adenomas and those with oxyphil-dominant parathyroid adenomas. SETTING: Tertiary care university hospital. PATIENTS: Sixty-three patients diagnosed as having a parathyroid adenoma. INTERVENTION: All patients underwent resection of a parathyroid adenoma following a preoperative technetium Tc 99m sestamibi localization study and serum calcium and parathyroid hormone level analysis. MAIN OUTCOME MEASURE: Technetium Tc 99m sensitivity rate. RESULTS: The overall technetium Tc 99m sestamibi sensitivity rate was 76.2%. The sensitivity within the chief and mixed cell-dominant (n = 52) and oxyphil cell-dominant groups (n = 11) were 71.2% and 100%, respectively (P = .04). There was no correlation between histologic findings of the lesion and its size or serum calcium and parathyroid hormone levels. CONCLUSIONS: Oxyphil cell predominance within an adenoma augments technetium Tc 99m sestamibi scan sensitivity in a statistically significant manner. The use of technetium Tc 99m sestamibi preoperative localization may therefore be differentially greater in patients with these types of lesions.

Chi-Square Distribution↗
PubMed1990

Exercise myocardial perfusion scintigraphy with technetium-99m methoxy isobutylisonitrile: a comparative study with thallium-201.

The evaluation of technetium-99m methoxy isobutylisonitrile for the diagnosis of coronary artery disease requires comparative validation against thallium-201, the established perfusion imaging agent. We have compared myocardial and lung uptake of both radiotracers following maximal exercise in 52 patients: 40 with angiographically proven coronary disease. Qualitative and quantitative image analysis showed the diagnostic sensitivity of technetium-99m methoxy isobutylisonitrile to compare favourably with that of thallium-201 as reflected by the mean number of ischaemic segments identified: 5.6 +/- 2.5 vs 4.8 +/- 2.1 by qualitative analysis, and 5.7 +/- 3.2 vs 5.0 +/- 2.6 segments by quantitative analysis. More reversibly ischaemic segments per patient were identified with technetium-99m methoxy isobutylisonitrile than with thallium-201: 3.6 +/- 2.3 vs 1.8 +/- 1.9. There was a higher exercise myocardial to background count ratio with technetium-99m methoxy isobutylisonitrile: 3.16:1 vs 2.58:1, and the mean exercise lung uptake normalised to left ventricular uptake ('lung index'), was lower for technetium-99m methoxy isobutylisonitrile than for thallium-201 (36 +/- 8% vs 40 +/- 10%). Five of the six patients with abnormal elevation of the thallium-201 exercise lung index also had elevation of the technetium-99m methoxy isobutylisonitrile exercise lung index, and all had extensive coronary artery disease. These results indicate that technetium-99m methoxy isobutylisonitrile is at least as effective as thallium-201 for detecting exercise induced myocardial ischaemia. However, technetium-99m methoxy isobutylisonitrile provides a better image quality and may be a more sensitive marker of defect reversibility. For both radiotracers lung uptake is increased with extensive coronary artery disease and measurement of this variable provides prognostic information.

Coronary Disease↗
PubMed1997

Modeling of subcutaneous absorption kinetics of infusion solutions in the elderly using technetium.

Absorption kinetics of solutes given with the subcutaneous administration of fluids is ill-defined. The gamma emitter, technitium pertechnetate, enabled estimates of absorption rate to be estimated independently using two approaches. In the first approach, the counts remaining at the site were estimated by imaging above the subcutaneous administration site, whereas in the second approach, the plasma technetium concentration-time profiles were monitored up to 8 hr after technetium administration. Boluses of technetium pertechnetate were given both intravenously and subcutaneously on separate occasions with a multiple dosing regimen using three doses on each occasion. The disposition of technetium after i.v. administration was best described by biexponential kinetics with a Vss of 0.30 +/- 0.11 L/kg and a clearance of 30.0 +/- 13.1 ml/min. The subcutaneous absorption kinetics was best described as a single exponential process with a half-life of 18.16 +/- 3.97 min by image analysis and a half-life of 11.58 +/- 2.48 min using plasma technetium time data. The bioavailability of technetium by the subcutaneous route was estimated to be 0.96 +/- 0.12. The absorption half-life showed no consistent change with the duration of the subcutaneous infusion. The amount remaining at the absorption site with time was similar when analyzed using image analysis, and plasma concentrations assuming multiexponential disposition kinetics and a first-order absorption process. Profiles of fraction remaining at the absorption site generated by deconvolution analysis, image analysis, and assumption of a constant first-order absorption process were similar. Slowing of absorption from the subcutaneous administration site is apparent after the last bolus dose in three of the subjects and can be associated with the stopping of the infusion. In a fourth subject, the retention of technetium at the subcutaneous site is more consistent with accumulation of technetium near the absorption site as a result of systemic recirculation.

Absorption↗
PubMed1993

Polymer-derivatized technetium 99mTc-labeled liposomal blood pool agents for nuclear medicine applications.

By using the lipophilic chelator, dipalmitoylphosphatidylethanolamine-diethylenetriaminetetraacetic acid (DPPE-DTTA), lipid vesicles may be prepared labeled on their surface with technetium 99m. When technetium-labeled vesicles were injected intravenously into rabbits, the half-life for clearance of the label from the circulation was less than 30 min. By further incorporating a synthetic phosphatidylethanolamine-monomethoxypoly(ethylene glycol) 5000 conjugate (PE-MPEG) the circulation half-life of the radiolabel was increased, liver uptake decreased and exchange of technetium from the vesicle surface suppressed, depending upon both the DPPE-DTTA and PE-MPEG content. For vesicles containing 20 mol% DPPE-DTTA, incorporation of PE-MPEG had no effect upon the circulation half-life of the radiolabel, however, for vesicles containing 2 mol% DPPE-DTTA, incorporation of more than 4 mol% PE-MPEG increased the circulation half-life of the label to more than 12 h. Less than 2 mol% PE-MPEG or 8 mol% ganglioside GM1 were, however, ineffective at increasing the circulation half-life of surface-bound technetium. It was shown that unilamellar lipid vesicles with DPPE-DTTA can be lyophilized in the presence of external sucrose, subsequently rehydrated with no change in vesicle size and labeled with technetium. It is suggested that polymer-derivatized, technetium-labeled vesicles may prove a useful substitute for technetium-labeled red blood cells as a vascular marker in various nuclear medicine procedures and that lyophilization/rehydration provides a possible route to realization of such vesicles in a pharmaceutically useful form.

Animals↗
PubMed1989

Technetium-99m isonitrile myocardial uptake at rest. I. Relation to severity of coronary artery stenosis.

To determine the potential of planar technetium-99m methoxybutyl isonitrile myocardial imaging as a method of detecting totally occluded or severely stenosed coronary arteries, the regional distribution of technetium-99m isonitrile at rest was compared with the coronary anatomy in 38 patients with prior myocardial infarction who underwent coronary arteriography. Left ventricular technetium-99m isonitrile tracer uptake at rest was assessed in the three major coronary vascular territories. When qualitative rest technetium-99m isonitrile uptake was markedly reduced or absent (grade 0), there was a 91% probability of finding a totally occluded or severely stenosed coronary artery. When qualitative tracer uptake was reduced (grade 1) or normal (grade 2), it excluded all territories supplied by a totally occluded vessel with poor collateral flow. Quantitative technetium-99m isonitrile uptake (mean +/- 1 standard deviation) in territories supplied by an occluded coronary artery with poor collateral flow (42 +/- 21%) was lower than in territories supplied by a vessel with less than 50% stenosis (87 +/- 10%) and 50 to 99% stenosis (74 +/- 19%) (p less than 0.001). Furthermore, technetium-99m isonitrile uptake in areas supplied by an occluded coronary artery with good collateral flow (61 +/- 23%) was lower than in areas supplied by a vessel with less than 50% stenosis (87 +/- 10%) (p less than 0.001). Because rest technetium-99m isonitrile imaging detects coronary occlusion with poor collateral flow, this method may be useful in assessing patients with acute myocardial infarction.

Adult↗
PubMed1993

Separate acquisition rest thallium-201/stress technetium-99m sestamibi dual-isotope myocardial perfusion single-photon emission computed tomography: a clinical validation study.

OBJECTIVES: This study assessed the validity of a novel approach to myocardial perfusion scintigraphy that provides the opportunity to avoid the drawbacks of standard same-day rest/stress technetium-99m sestamibi myocardial perfusion studies by using separate-acquisition dual-isotope rest thallium-201 and exercise technetium-99m sestamibi single-photon emission computed tomography (SPECT). BACKGROUND: Standard same-day rest/stress technetium-99m sestamibi myocardial perfusion studies are cumbersome, associated with a potential decrease in perceived stress defect severity compared with thallium-201 due to the presence of rest technetium-99m sestamibi and may be unable to differentiate hibernating from infarcted myocardium. METHODS: The dual-isotope procedure was performed in 63 patients without previous myocardial infarction undergoing coronary angiography to evaluate sensitivity and specificity for coronary artery disease and in 107 patients with a low (< 5%) likelihood of coronary artery disease to evaluate normalcy rate. To validate defect reversibility, the dual-isotope SPECT study was compared with stress/rest technetium-99m sestamibi SPECT studies in a separate group of 31 patients with previous documented myocardial infarction who underwent a rest technetium-99m sestamibi study in addition to the dual-isotope SPECT study. RESULTS: In angiographic correlations, dual-isotope SPECT demonstrated high sensitivity for detecting patients with > or = 50% stenosis (91%, 55 patients) and > or = 70% stenosis (96%, 52 patients). In a small group of patients, high specificity was also observed (75% for < 50% stenosis [8 patients] and 82% for < 70% stenosis [11 patients]). A very high normalcy rate of 95% was also found. In the patient group assessed for defect reversibility, in zones with no previous myocardial infarction, segmental agreement for defect type between rest thallium-201 and rest technetium-99m sestamibi studies was 97% (kappa = 0.79, p < 0.001). In myocardial infarct zones, segmental agreement for defect type was 98% (kappa = 0.93, p < 0.001). Image quality was generally good to excellent. CONCLUSIONS: Our findings demonstrate that separate-acquisition dual-isotope myocardial perfusion SPECT is accurate for coronary artery disease detection, correlates well with rest-stress sestamibi studies for assessment of defect reversibility and results in good to excellent image quality. This approach provides an excellent method for the combined assessment of stress myocardial perfusion and myocardial viability.

Aged↗
PubMed1999

Technetium-99m-EC and other potential new agents in renal nuclear medicine.

Search for the ideal radiopharmaceutical to measure effective renal plasma flow (ERPF) has been underway since the early 1960s. Although ortho-iodohippuran (OIH) has biological properties suited for measurement of ERPF, the imaging characteristics are less than desirable. With the advent of the molybdenum-99/technetium-99m generators, efforts have focused on the development of a technetium-99m agent to measure ERPF. Over the last 10 to 15 years several promising technetium-99m renal imaging agents have been developed. Early examples of technetium-99m renal agents such as 99mTc-CO2DADS and 99mTc-PAHIDA, although not ideal replacements for OIH, demonstrated that a technetium-99m complex could be actively transported by the renal tubules and provided the impetus for development of new technetium-99m renal agents. The next breakthrough in technetium-99m renal agents was the development of the triamide mercaptide class of chelating agents by Fritzberg et al. To date the most promising compound in this class is mercaptoacetyltriglycine (MAG3). 99mTc-MAG3 is currently the agent of choice, but it is by no means the perfect replacement for OIH. Problems with high plasma protein binding and clearances that are only 50% to 60% of the OIH clearance make measurement of ERPF difficult. The serendipitous discovery that metabolites of the brain agent 99mTc-ethylenedicysteine diethylester (99mTc-L,L-ECD) are rapidly excreted in the urine has led to the evaluation of 99mTc-L,L-ethylenedicysteine (99mTc-L,L-ECD) as a potential renal imaging agent. Studies that have evaluated 99mTc-L,L-EC in animals, normal human volunteers, and patients with various renal disorders reveal that the renal clearance of 99mTc-L,L-EC is higher than 99mTc-MAG3 and more closely approaches that of OIH. Other approaches that are being examined in the development of the ideal renal imaging agent include substitution of various amino acids for glycine residue in MAG3 and technetium-99m labeled organic cations.

Animals↗
PubMed1996

Comparison of exercise stress testing with simultaneous dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computerized tomography for diagnosis of coronary artery disease.

The object of our study was to compare the value of exercise stress testing with simultaneous dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography for the diagnosis of coronary artery disease. Sixty-nine patients with either suspected or proven coronary artery disease underwent simultaneous dobutamine technetium-99m isonitrile single-photon emission computed tomography and stress echocardiography, and treadmill exercise electrocardiography. Dobutamine echocardiography and technetium-99m isonitrile single-photon emission computed tomography revealed a higher overall sensitivity than exercise testing (94 vs 60%, P < 0.001), but dobutamine stress echocardiography showed a higher specificity than both technetium-99m isonitrile single-photon emission computed tomography and exercise testing (86 vs 64%, P < 0.05, for both tests). In addition, the diagnostic accuracy of dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography was higher than that of exercise testing (91 vs 61%, P < 0.001; 86 vs 61%, P < 0.001, respectively). Dobutamine stress echocardiography and technetium-99m isonitrile single-photon emission computed tomography are superior to exercise testing in the diagnosis of coronary artery disease, and dobutamine stress echocardiography can act as an alternative to technetium-99m isonitrile single-photon emission computed tomography.

Adult↗
PubMed1994

Preoperative parathyroid localization: prospective evaluation of technetium 99m sestamibi.

The utility of preoperative parathyroid localization remains controversial. The gold standard for identification of abnormal parathyroid glands is exploration of the neck by an experienced surgeon. However, both for the experienced and less experienced surgeon, it may be desirable to localize the abnormality before surgery. Such a study would not only direct the surgeon to the site of the lesion but also would help reduce unnecessary dissection, the number of negative explorations, and operative anesthesia time. Unfortunately, currently used noninvasive techniques including ultrasonography, thallium-technetium subtraction, computed tomography scan, and magnetic resonance imaging have had only limited success (35% to 78%) in demonstrating abnormal parathyroid glands. Thirty patients with proven hyperparathyroidism were enrolled to compare a new imaging agent, technetium 99m sestamibi, as an alternative to thallium 201 for subtraction scintigraphy with technetium 99m pertechnetate. Only 14 of 30 patients operated on at George Washington University underwent an identical surgical approach (exploration of all four glands) and had complete preoperative calcium and parathormone levels, postoperative calcium levels, and total time of surgical procedures to formulate the basis of this report. The remaining 16 had their surgeries at other institutions. A surgical approach different from that used at George Washington University and unavailability of postoperative calcium levels and times of surgical procedures from these institutions necessitated deletion of these 16 patients from this report. Technetium 99m sestamibi-technetium 99m subtraction scans accurately localized the abnormal parathyroid gland in 13 of 14 patients, as compared with only 9 of 14 thallium 201-technetium 99m pertechnetate subtraction scans. These results support technetium 99m sestamibi scanning as the superior modality for preoperative parathyroid localization.

Adult↗