Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TECHNETIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 919 records · Page 51Linked to original sources
PubMed1993

Noninvasive measurements of regional cerebral blood flow using technetium-99m hexamethylpropylene amine oxime.

The previously reported method for quantitative measurements of whole-brain or hemispheric-brain perfusion using technetium-99m hexamethylpropylene amine oxime (HMPAO) radionuclide angiography is now further developed so that regional cerebral blood flow (rCBF) can be measured. Lassen's correction algorithm is used for the linearization of a curve-linear relationship between the radioactivity in the brain and blood flow as seen with single-photon emission tomography (SPET) images. In this algorithm, the cerebral hemisphere was chosen as the reference region and the correction factor alpha was adapted to rCBF in the reference region. This new method of measuring CBF from SPET has been validated in 33 normal subjects and 22 patients with cerebrovascular disease. Regional CBF values in 20 brain regions of the normal subjects were in good agreement with reported values measured by other methods. Regional CBF in the frontal cortex was greater than that in the temporal, parietal or occipital cortex for the entire age range. This hyperfrontal perfusion tended to be less pronounced with advancing age. Seventeen patients with unilateral brain infarction showed significantly lower rCBF than normal subjects. The infarct core showed a low rCBF value of 11.1 ml/100 g/min on average. An increase in rCBF after acetazolamide administration was observed and measured with this method in five patients with unilateral occlusive vascular pathology. These results suggest that this non-invasive method (without any blood sampling) permits the routine measurement of rCBF from HMPAO SPET tomograms of blood flow.

Acetazolamide↗
PubMed1994

First evaluation of technetium-99m dimercaptopropionyl albumin as a possible tracer agent for ventriculography in a volunteer.

Technetium-99m labelled red blood cells (99mTc-RBCs) are the standard radiopharmaceutical for radionuclide ventriculography but suffer from some practical disadvantages such as risk of viral contamination and lengthy preparation (in vitro labelling) or poor labelling efficiency due to patient medication interactions (in vivo labelling). 99mTc-labelled human serum albumin (HSA) is not really a valuable alternative as the activity diffuses too rapidly out of the vascular space due to the weak binding of the radionuclide. We have modified HSA by reaction with N-hydroxysuccinimidyl 2,3-di(S-acetylmercapto)propionate (SAMP) to introduce a varying number of 2,3-dimercaptopropionyl (DMP) side chains. The resulting DMP-HSA can be rapidly labelled with 99mTc at room temperature by simple addition of stannous ions and eluate of a 99mTc generator. After evaluation in mice and rabbits, two different 99mTc-DMP-HSA preparations - obtained after reaction of SAMP with albumin in a molar ratio of, respectively, 8:1 and 16:1 - were tested in a volunteer and compared to 99mTc-RBCs. The blood time-activity curves of the three preparations were quite similar but both 99mTc-DMP-HSA preparations were excreted much less into the urine than 99mTc-RBCs. Ventriculography was performed with the three tracer agents, each time with a 1-week interval. In the three studies, the heart was clearly visualized and the left and right ventricle could be easily delineated. The ejection fractions obtained after administration of the three preparations were similar. With both 99mTc-DMP-HSA preparations the low activity in the spleen was a distinct advantage and facilitated delineation of the left ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Erythrocytes↗
PubMed1994

Evaluation of technetium-99m exametazime stabilised with cobalt chloride as a blood flow tracer in focal cerebral ischaemia.

A protocol has been devised to effectively extend the limited post-reconstitution shelf life of technetium-99m exametazime as a radiopharmaceutical for imaging cerebral blood flow (CBF) distribution. The potential of 99mTc-exametazime stabilised with cobalt chloride for imaging CBF distribution as late as 4 h after reconstitution has been examined in ischaemic and non-ischaemic tissue in halothane-anaesthetised cats. Focal cerebral ischaemia was produced by permanent middle cerebral artery occlusion. The relationship between 99mTc-exametazime uptake and retention and CBF (assessed with [14C]iodoantipyrine 10 min after first radiopharmaceutical administration) was determined in the same tissue section with double label autoradiography. Over the CBF range 0-80 ml 100 g-1 min-1, the uptake of 99mTc-exametazime (quantitatively and topographically) was linearly related to CBF irrespective of whether the 99mTc-labelled tracer was unstabilised (and administered within 10 min of reconstitution) or was stabilised with cobalt chloride (and administered up to 240 min after reconstitution). For levels of CBF in excess of 80 ml 100 g-1 min-1 the excellent topographical relationship between 99mTc-exametazime distribution and CBF is maintained but quantitatively, 99mTc-exametazime underestimates CBF to a similar degree in animals receiving stabilised and unstabilised 99mTc-exametazime. The presence of the stabiliser, cobalt chloride, extends greatly the period over which 99mTc-exametazime can be used after reconstitution to generate images of CBF distribution in normal and ischaemic cerebral tissue.

Animals↗
PubMed1994

Assessment of tumour necrosis and detection of mediastinal lymph node metastasis in bronchial carcinoma with technetium-99m sestamibi imaging: comparison with CT scan.

Thirty-eight patients with four major types of bronchial carcinoma were studied to evaluate technetium-99m sestamibi imaging in the assessment of tumour necrosis and the detection of hilar and mediastinal lymph node metastasis. Quantitative analysis was also performed to ascertain whether tumour uptake values correlate with histological types of bronchial carcinoma. Of the patients, 34 showed tumour uptake on planar imaging (n = 38) and 27 on single-photon emission tomography (SPET) (n = 29), the overall sensitivity in the localisation of primary tumour being 89% with planar imaging and 93% with SPET. Four types of tumour uptake pattern were identified: (1) focal uptake, (2) focal uptake with a central hypoactive focus. (3) ring-like uptake and (4) no uptake (negative uptake). Tumour necrosis was diagnosed in 12 patients based upon histopathology (n = 2) and density measurements and type of contrast enhancement on computed tomography (CT) scan (n = 12). Defective tumour uptake was seen in 11 of these patients on planar images (focal uptake with a central hypoactive focus, n = 7; ring-like uptake, n = 2; and no tumour uptake, n = 2) and in 12 patients on SPET (focal uptake with a central hypoactive focus, n = 7, ring-like uptake, n = 3, and no uptake, n = 2). Hilar and mediastinal lymph node involvement was detected in ten patients on CT scan, nine on planar images and 11 on SPET. A total of 26 metastatic lymph nodes were detected on CT scan: 24 of these were seen on planar, and all 26 on SPET images.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1994

The role of technetium-99m sestamibi whole-body scans in diagnosing metastatic Hürthle cell carcinoma of the thyroid gland after total thyroidectomy: a comparison with iodine-131 and thallium-201 whole-body scans.

Thirty-seven patients with Hürthle cell carcinoma of the thyroid gland underwent total thyroidectomy and then technetium-99m sestamibi (2-methoxy-isobutylisonitrile), iodine-131 and thallium-201 whole-body scans. Twenty-two of them had elevated human serum thyroglobulin (HTg) levels. Among these 22 patients, abnormal uptake of 131I was seen in four (18.1%), abnormal uptake of 201Tl chloride in 15 (68.1%), and abnormal 99mTc-sestamibi accumulation in 18 (81.8%). No patients with normal levels had a positive whole-body scan. In comparison with the 131I and 201Tl chloride images, the 99mTc-sestamibi images were of superior quality and detected significantly more (P < 0.05) metastatic lesions of Hürthle cell carcinoma of the thyroid gland in patients with elevated HTg after total thyroidectomy. A mechanism is proposed that may explain these findings.

Adenocarcinoma↗
PubMed1994

Technetium-99m sestamibi: an indicator of breast cancer invasiveness.

As recently shown, angiogenesis is the most reliable marker of breast cancer invasiveness. Unfortunately it must be assessed by immunohistochemistry on tissue specimens. We have used technetium-99m sestamibi, a marker of regional blood flow in other organs that often but not always images breast cancer, to assess the invasiveness of this tumour. Nineteen patients, ten with nodal metastases and nine without any metastases, were studied with 99mTc-sestamibi scintigraphy before operation. Angiogenesis was quantitatively assessed by immunohistochemical staining of endothelia for factor VIII. All the node-positive (N+) patients at surgical revision showed a positive 99mTc-sestamibi scan of the primary tumour and all the N-patients were negative. Nine out of ten N+ and sestamibi-positive tumours showed more than 135 microvessels/mm2 and one showed 99 microvessels/mm2; by contrast there were 71.6 +/- 12.1 microvessels/mm2 in the nine N- and sestamibi-negative tumours. Our study suggests that 99mTc-sestamibi is a marker of breast cancer invasiveness: its uptake is related to angiogenesis and, possibly, to oxidative metabolism of the tumour.

Adult↗
PubMed1994

Simultaneous gallium-67 citrate and technetium-99m sestamibi SPET in a case of myocardial lymphoma: comparison with echocardiography before and after chemotherapy.

A patient with diffuse large cell lymphoma involving the interventricular septum and the inferior ventricular wall was imaged with a simultaneous dual-isotope single-photon emission tomography (SPET) acquisition technique, using the radiotracers technetium-99m hexakis 2-methoxyisobutylisonitrile (sestamibi) and gallium-67 citrate, in conjunction with echocardiography, prior to and following the first course of chemotherapy. Simultaneous acquisition--with the advantage of displaying corresponding sets of SPET slices without any need for position correction--, supplemented by echocardiography, increased the accuracy of evaluation of the extent of disease and response to treatment.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

The skeleton in congenital, generalized lipodystrophy: evaluation using whole-body radiographic surveys, magnetic resonance imaging and technetium-99m bone scintigraphy.

Congenital generalized lipodystrophy (CGL) is a rare genetic disease characterized by the absence of body fat from birth. Focal bone lesions have also been reported, but their pathophysiology is poorly understood. To characterize skeletal abnormalities further in 3 patients with CGL, we employed whole-body radiographic skeletal surveys, magnetic resonance imaging (MRI, including gadolinium enhancement), and triple phase technetium-99m methylene diphosphonate bone scintigraphy. Radiographs showed numerous focal lesions within the long bones, as described in other reports. MRI showed that the entire marrow space of the long bones was abnormal and was characterized, at least in part, by the absence of marrow fat. Prolonged T1 and T2 times and marked gadolinium enhancement were observed in radiographically normal-appearing long bone. Radiographically lytic lesions occasionally demonstrated fluid-fluid levels on MRI and enhanced peripherally after gadolinium infusion. Bone scintigraphy findings such as periarticular hyperemia were relative subtle. We conclude that the appendicular skeleton of patients with CGL is diffusely abnormal and is predisposed to focal osteolysis and cyst formation.

Adult↗
PubMed1985

Technetium thiodiglycollic acid (99mTc-TDG). A new radiopharmaceutical with the potential for the assessment of renal function.

A mixture of hydrophilic complexes is formed on the reduction (employing tin metal as a reductant) of sodium pertechnetate 99mTc in the presence of the ligand thiodiglycollic acid (TDG). When administered to rats, the mixture demonstrated a renal clearance rate marginally greater than Glomerular filtration rate (GFR). HPLC analysis indicated the formation of two technetium complexes of TDG. After isolation of the complexes and their administration to rats, one (complex 1) showed renal clearance similar to that of 99mTc Diethylenetriamine pentaacetic acid (DTPA), while the other (complex 2) demonstrated renal clearance similar to that of 125I o-iodo hippuric acid. On heating the mixture of complexes, the proportion of the faster-clearing 99mTc TDG complex increased to 92% of the total activity, and the biodistribution of the material following heat rearrangement was equivalent to that of isolated complex 2.

Animals↗
PubMed1985

Paradoxical technetium-thallium subtraction scan in a case of parathyroid adenoma.

A technetium-thallium (99mTcO4-201Tl) subtraction scan was performed in a patient with clinical and biological evidence of hyperparathyroidism. The 201Tl image indicated a normal thyroid gland. The 99mTcO4 image revealed a left inferior thyroidal extension with an intense and transient focus corresponding to an ultrasonographic nodule. The transient character of the focus was not explicable in terms of vascular kinetics. A supplementary scintigram using 123I confirmed the presence of an inferior extension of the thyroid, but no increased uptake was found. A nodule weighing 250 mg containing a parathyroid adenoma surrounded by normal thyroidal tissue was excised at the focus site. Biological serum levels returned to normal after the operation. It is concluded that the analysis of 99mTcO4 dynamic data could improve the accuracy of parathyroid subtraction scintigraphy.

Adenoma↗
PubMed1984

Successful localisation of parathyroid adenomata by thallium-201 and technetium-99m subtraction scintigraphy: description of an improved technique.

An improved method for parathyroid scanning using thallium-201 and technetium-99m subtraction imaging is described. The technique successfully localised ten of eleven parathyroid adenomas confirmed at neck exploration. Two false-positive studies were encountered in patients with no adenoma at operation, probably due to thyroid nodules. The technique was less successful in identifying diffusely hyperplastic parathyroid glands and was negative in a single patient with recurrent, functional parathyroid carcinoma.

Adenoma↗
PubMed1994

Role of technetium-99m planar bone scanning in the evaluation of low back pain.

The records of 1018 patients with low back pain in a tertiary spine referral practice were reviewed. One hundred thirty-nine out of 1018 (13.6%) underwent technetium-99m planar bone scanning as part of their investigation. Seventy-three out of 139 scans (52%) showed increased uptake in some area, but only 27 out of 139 (19.4%) showed increased uptake specifically in the low back. Scans consistently yielded no findings with reference to the back when the prescan diagnosis was spinal stenosis, lumbar pain syndrome, herniated nucleus pulposus, or postlaminectomy syndrome. Some scans gave positive findings in patients with a diagnosis of degenerative disc disease, pseudarthrosis, spondylolisthesis, fracture, infection, metabolic disorder, or tumor. Positive scans were generally obtained early after presentation (within 3 months) and negative scans obtained later (after 6 months), suggesting that clinical suspicion is still the main indication for early scanning. Planar bone scanning was helpful in both diagnosis and therapeutic decision-making in many conditions.

Adolescent↗
PubMed1987

Technetium Tc 99m plasmin in the diagnosis of inflammatory disease.

The localization characteristics of technetium Tc 99m plasmin were studied in experimental animals to investigate the use of 99mTc-plasmin for imaging inflammatory processes. At various times after abscess induction using turpentine in rats, the in vivo distribution properties of 99mTc-plasmin, gallium citrate Ga 67, 125I-fibrinogen, and 99mTc-human serum albumin (HSA) were studied by gamma-camera imaging. The in vivo binding of each radiopharmaceutical was also tested in rat and human plasma clots. Region-of-interest analyses of gamma-camera images showed relatively poor 99mTc-plasmin localization at sites of abscess formation. The ratio of abscess-to-control activity of this radiopharmaceutical did not exceed that of 67Ga, 125I-fibrinogen, or 99mTc-HSA. In vitro assays of each of the radiopharmaceuticals in plasma clots showed 99mTc-plasmin and 125I-fibrinogen to have the best localization characteristics.

Abscess↗
PubMed1979

An evaluation of six kits of technetium 99m human serum albumin injection for cardiac blood pool imaging.

We have investigated the suitability of five different commercially available kits which provide human serum albumin (HSA) labelled with technetium 99m (99mTc) for cardiac blood pool imaging. Four of these products were one-step processes using stannous chloride as the reducing agent; the fifth was based on an electrolytic reduction. In addition, we also assessed our own modification of the electrolytic method. We measured the radiochemical purity by precipitation with trichloroacetic acid and by gel filtration on a Biogel P4 column. In addition, we measured the clearance of radioactivity from the blood at frequent time intervals after intravenous injection. Each product was assessed in separate groups of six patients. The labelling efficiency of the one-step kits varied between 73 and 93% compared with 94 and 98% for the electrolytically labelled albumin. The blood clearance for all one-step kits was significantly faster than that obtained for the radiopharmaceuticals prepared by the electrolytic method. We conclude that HSA labelled with 99mTc by the electrolytic method is to be preferred.

Cardiac Volume↗
PubMed1994

Determination of tumour vascularity using selective hepatic angiography as compared with intrahepatic-arterial technetium-99m macroaggregated albumin scan in hepatocellular carcinoma.

A total of 51 patients with hepatocellular carcinoma (HCC) were studied to determine the tumour vascularity as determined by selective hepatic angiography (HAG) and by intrahepatic-arterial technetium-99m-labeled macroaggregated albumin (Tc99m-MAA) scan. The tumour vascularity was graded on the HAG films by an interventional radiologist using a scale ranging from 1 (hypovascular) to 4 (extremely hypervascular). The grades of vascularity on HAG were grade 1 in 5 patients, grade 2 in 13 patients, grade 3 in 24 patients and grade 4 in 9 patients. The tumour vascularity on scintigraphy was determined by quantifying the count rates over the tumour and normal liver areas by an analog/digital gamma-camera, and the resultant tumour-to-normal ratio (T/N ratio) gave a quantitative measure of the vascularity. The range of the T/N ratio was 0.9 to 11.1, with a median of 3.7. There was no correlation between the tumour vascularity grading on HAG and the T/N ratio on the Tc99m-MAA scan (Wilcoxon rank test, P = 0.83). Thus, we conclude that HAG cannot reveal the true vascularity nor reflect the T/N ratio in HCC.

Angiography↗
PubMed1993

Detection of adriamycin-induced cardiotoxicity in cultured heart cells with technetium 99m-SESTAMIBI.

Adriamycin, a broad-spectrum cytotoxic agent useful in cancer chemotherapy, is limited by a dose-dependent cardiomyopathy mediated in part by disruption of mitochondrial energetics. Hexakis(2-methoxyisobutyl isonitrile)technetium(I) (99mTc-SESTAMIBI) is a gamma-emitting radiopharmaceutical with myocellular accumulation properties dependent on mitochondrial membrane potential. To test the hypothesis that 99mTc-SESTAMIBI could monitor Adriamycin-induced alterations in cardiac energetics, cultured chick heart cells were treated with Adriamycin and 99mTc-SESTAMIBI tracer kinetics were determined. Concentration- and time-dependent depression of 99mTc-SESTAMIBI accumulation was evident within 60 min of treatment. The apparent Ki for acute Adriamycin inhibition of tracer accumulation was 82 microM. After 24 h of treatment, Adriamycin concentrations as low as 0.1 microM demonstrated detectable inhibitory effects. The apparent Ki for this subchronic Adriamycin inhibition of 99mTc-SESTAMIBI accumulation was 18 microM. Subchronic concentration-dependent increases in adriamycin-induced myocellular injury as reflected by lactate dehydrogenase (LDH) release correlated inversely with decreases in 99mTc-SESTAMIBI accumulation. These data further support a contribution from altered mitochondrial energetics to Adriamycin-induced injury and establish a pharmacological foundation for pursuing the possibility of noninvasive imaging of chronic Adriamycin cardiotoxicity in cancer patients using 99mTc-SESTAMIBI.

Analysis of Variance↗
PubMed1995

Brain single-photon emission tomography with technetium-99m hexamethylpropylene amine oxime in adolescents with initial-stage schizophrenia.

The objective of this study was to search for regional cerebral blood flow (rCBF) abnormalities in adolescents with initial-stage schizophrenia by means of brain single-photon emission tomography (SPET) using technetium-99m hexamethylpropylene amine oxime (HMPAO). SPET studies were performed on a homogeneous sample of 15 carefully selected adolescents with a recent diagnosis of schizophrenia, and without previous electroconvulsive or antipsychotic drug treatment. Computed tomography (CT) and electro-encephalographic (EEG) studies were performed in all patients. Qualitative and semiquantitative analysis of 99mTc-HMPAO SPET studies showed an impaired rCBF in 12 patients (80%). The most common pattern was a decreased uptake of 99mTc-HMPAO in the frontal lobes, usually in the left hemisphere. Conventional and quantitative EEG was positive in 12 (80%) and 15 (100%) patients, respectively. CT findings were positive in two patients (13%). There was a high level of concordance between SPET and EEG results and between SPET and clinical features (P>0.05). This study suggests that previously untreated patients in the first stages of schizophrenia present functional abnormalities that are revealed by brain SPET.

Adolescent↗