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PubMed2003

Pilot study using technetium-99m pertechnetate sequential radionuclide-sialography to assess salivary gland function in nasopharyngeal cancer patients on radiation therapy.

INTRODUCTION: Nasopharyngeal carcinoma (NPC) is mainly treated by radiation therapy. A common complication of radiotherapy is xerostomia. Direct measurements of the amount of saliva produced using suction cups and volumetric assessments are cumbersome and time-consuming. Sequential radionuclide sialography is a reproducible and convenient method of measuring salivary function. MATERIALS AND METHODS: Patients with newly diagnosed NPC underwent a pilot study using technetium-99m pertechnetate sequential radionuclide sialography to assess their salivary function before and at 3 months post radiation therapy. From the sialography, time activity curves were obtained for analysis of salivary function. The shape of the time activity curve with citric acid stimulation was classified into 4 types according to the degree of radiation-induced dysfunction. RESULTS: All 14 patients had worse (P < 0.005) time activity curves for both parotids and submandibular glands after radiation therapy. All patients with abnormal curves before radiation therapy presented type IV (non-functioning) curve after radiation therapy. A ratio of pre- and post-stimulation counts allowed for quantification of the degree of stimulatory response. We found a significant decrease in Rc before and after radiation therapy for all salivary glands (P < 0.001). The salivary gland to background ratio, which is a reflection of the degree of salivary gland functional uptake, also had a significant reduction after radiation. CONCLUSION: It is feasible to use technetium-99m pertechnetate in the measurement of salivary gland function in nasopharyngeal cancer patients treated with radiation therapy.

Adult↗
PubMed1992

Human pharmacokinetics and radiopharmacological studies of the myocardial perfusion agent: technetium (2-carbomethoxy-2-isocyano-propane)6+.

The myocardial perfusion agent technetium (2-carbomethoxy-2-isocyano-propane)6+ (99mTc-CPI) is unique from other cationic technetium isonitrile complexes in that it exhibits moderate washout from the heart and rapid hepatobiliary clearance in animal models and human volunteers. Dynamic imaging and HPLC analysis were performed in humans and guinea pigs to outline the pharmacological basis of its pharmacokinetics. Enzymatic hydrolysis of the terminal ester groups in blood was found to occur at a moderate rate producing new species that have been shown not to accumulate in heart tissue. However, after extraction by the heart, liver or kidneys, the 99mTc-CPI complex undergoes metabolism at a much slower rate than observed in the blood. Differences in hydrolysis rate and products obtained indicate separate mechanisms of hydrolysis occurring in blood and other organs. It is proposed that the heart washout occurring after hydrolysis produces a neutral compound which is no longer retained by the negative cytosolic and mitochondrial membrane potentials in myocardial tissue.

Adult↗
PubMed2002

Detection of acute gastrointestinal bleeding by means of technetium-99m in vivo labelled red blood cells.

BACKGROUND: Prognosis of gastrointestinal (GI) bleeding depends on the timely [3] and accurate [8, 18] detection of the source of bleeding and sequential surgical or endoscopy therapy. Scintigraphy with red blood cells (RBCs) in vivo labelled by means of technetium-99m hastened detection of source of GI bleeding and improved management of the particular disease. Gastrointestinal endoscopy is the method of choice for the diagnostics of bleeding from upper tract and large bowel. For diagnostics of bleeding from the small bowel we can use scintigraphy with in vivo labelled autological red blood cells if push-enteroscopy, intra-operative enteroscopy or angiography are not available. MATERIAL AND METHODS: 31 patients (13 men, 18 women, aged 20-91, mean 56 years) underwent this investigation from 1998 till 2001 at the Department of Nuclear Medicine. All patients had melaena or enterorrhagia associated with acute anaemia. Gastroscopy, colonoscopy, enteroclysis or X-ray angiography did not detect the source of bleeding. RESULTS: Twenty-one patients had positive scintigraphy with in vivo labelled RBCs--9 patients were already positive on dynamic scintigraphy, and 12 patients were positive on static images. Scintigraphy with in vivo labelled RBCs was negative in 10 patients. GI bleeding stopped spontaneously in these 10 patients with negative scintigraphy. These patients did not undergo intra- operative enteroscopy or surgery. The final diagnosis of the 21 patients with positive scintigraphy was determined in 16 patients by push-enteroscopy (6 patients), intra-operative enteroscopy (6 patients) or by surgery (4 patients). Of these 16 patients the correct place of bleeding was determined by scintigraphy with labelled RBCs in 11 (69%) patients. Final diagnoses of our 16 patients with positive scintigraphy with autological labelled RBCs were: bleeding small bowel arteriovenous malformation (6 patients), uraemic enteritis with bleeding erosions in ileum and jejunum (2 patients), Osler-Rendu- Weber disease (1 patient), pseudocyst of the pancreas with bleeding vessel communicating to the transverse colon (1 patient), bleeding submucose varix in jejunum (1 patient), carcinoid of the ileum (1 patient), bleeding from the ileosigmoideoanastomosis six days after hemicolectomy for Crohn's disease (1 patient), bleeding from an ulcer close to the papilla of Vater (1 patient), bleeding from ulcer at jejunum after previous NSAIDs treatment (1 patient), bleeding inflammatory polyp at ileotransversoanastomosis (1 patient). GI bleeding stopped spontaneously in 5 patients with positive scintigraphy. Therefore these patients did not undergo intraoperative enteroscopy or surgery and we could not determine the final diagnosis. CONCLUSIONS: Scintigraphy with RBCs in vivo labelled technetium- 99m hastened detection of the source of GI bleeding and improved management of the source of GI bleeding and improved management of disease.

Journal Article↗
PubMed1991

Early scintigraphic detection of experimental myocardial infarction in dogs with technetium-99m-glucaric acid.

Recent data have generated some interest in technetium-99m-(99mTc) glucaric acid as an in vivo viability marker. We studied 99mTc-glucaric acid retention in canine models of myocardial ischemia (20-min occlusion of the LAD/40-min reperfusion), acute myocardial infarction (MI) (90-min LAD occlusion/3-hr reperfusion), and chronic MI (90-min occlusion and either 48-hr or 10-day reperfusion). Regional myocardial blood flow was measured by radiolabeled microspheres. No preferential uptake of glucaric acid was observed in ischemic but viable myocardium. The compound showed high affinity for necrotic myocardial tissue for several days following injury. The preferential uptake in infarcted tissue disappeared by 10 days following injury. This study shows that 99mTc-glucaric acid acts exclusively as a marker of necrosis in canine models of MI. Technetium-99m-glucaric acid may have clinical utility in early cardiac imaging of myocardial infarction and in differentiating recent from old injuries.

Animals↗
PubMed1989

A neutral technetium-99m complex for myocardial imaging.

Technetium-99m-CDO-MeB [Bis[1,2-cyclohexanedione-dioximato(1-)- O]-[1,2-cyclohexanedione dioximato(2-)-O]methyl-borato(2-)- N,N',N'',N''',N'''',N''''')-chlorotechnetium) belongs to a family of compounds generally known as boronic acid adducts of technetium dioxime complexes (BATOs). It has an intrinsic affinity for the myocardium, with negligible lung activity and rapid blood clearance. The uptake of 3.44% ID in rat heart at 1 min postinjection for [99mTc]CDO-MeB versus 3.03% for 201TI indicates high extraction of [99mTc]CDO-MeB by the myocardium. In dogs an ischemic defect is clearly seen in SPECT images obtained 10 min after injection of [99mTc]CDO-MeB. Tissue distribution data in rats show that [99mTc]CDO-MeB is excreted primarily in the feces and to a lesser extent in the urine. Approximately 80% of the activity is excreted within 24 hr after injection.

Animals↗
PubMed1987

Preoperative localization of lesions of the parathyroid gland using thallium-technetium scintiscanning.

Double tracer scanning of the neck after injection of thallium-210 and technetium pertechnetate was performed upon 33 patients with biochemically proved hyperparathyroidism operated upon during the past 14 months. Operative findings were correlated with the scans. Twenty-two of 29 single lesions of the parathyroid gland were successfully localized. There were ten unsuccessful studies, including three instances in which diffuse hyperplasia was incompletely identified. In one instance of diffuse hyperplasia, the bilateral pathologic finding was diagnosed correctly. Two of three substernal lesions were demonstrated in patients who had undergone previous unsuccessful explorations. An additional substernal lesion was localized in a patient prior to initial exploration. Nineteen of 21 lesions weighing more than 300 milligrams were identified, whereas only 50 per cent of the lesions weighing less than 300 milligrams could be seen. The scans demonstrated 12 of 14 lesions with C-terminal parathyroid hormone levels of more than 900 picograms per milliliter but only 60 per cent of the lesions that produced levels of less than 900 picograms per milliliter. Thallium-technetium scanning is a useful procedure for preoperative localization of parathyroid lesions and may preclude the need for more invasive testing in previously operated upon patients.

Aged↗
PubMed1988

Scintigraphic imaging of technetium 99m-labeled neutrophils in the dog.

Autologous canine neutrophils were labeled with technetium 99m and reinjected in 7 dogs with experimentally induced focal abscesses to determine the ability of scintigraphy to localize a focus of sepsis (abscess). Good localization of labeled cells in an abscess was achieved; however, a large portion of the technetium 99m eluted from the neutrophils.

Abscess↗
PubMed1987

Routine use of the thallium-technetium scan prior to parathyroidectomy.

The merit of the preoperative localization of parathyroid tumors with thallium-technetium subtraction imaging is a subject of current debate in the treatment of primary hyperparathyroidism. Eighty patients with hyperparathyroidism underwent preoperative subtraction scintigraphy with 201Tl Cl and 99mTcO4; scan results were correlated with the operative identification and histopathology of the resected parathyroid tissue. The true-positive, false-positive and false-negative rates of these scans were compared between patients with tumors in normal and ectopic anatomic locations and between patients undergoing an initial and reoperative neck exploration. The scan was clearly valuable in patients with one or more prior neck explorations. True-positive scans were obtained in seven (77%) of nine such patients. The scan was also valuable in patients who had ectopic tumors (six mediastinal, seven intrathyroid, and two in the carotid sheath). Twelve (80%) of these 15 ectopic tumors were correctly localized either prior to their first operation or before subsequent explorations. In contrast, only 33 (50%) of 65 patients had a true-positive scan prior to their first operation and when the tumor was not in an ectopic location. In summary, in this series, the thallium-technetium scan was correct in only 50 per cent of patients undergoing an initial operation. However, it was positive in 77 per cent of patients who had at least one prior neck exploration and in 80 per cent of patients with an ectopic parathyroid tumor. These results support the selective use of this valuable imaging and localization tool.

Adenoma↗
PubMed1995

Evaluation of technetium-99m-ethylenedicysteine in renal disorders and determination of extraction ratio.

UNLABELLED: This article evaluates the clinical usefulness of 99mTc-ethylenedicysteine (EC) in patients with various renal disorders. In addition, extraction ratios of 99mTc-EC in five volunteers were also determined. METHODS: Twenty patients were intravenously injected with 200 MBq 99mTc-EC and 2.5 MBq [131I]orthoiodohippurate (OIH) simultaneously and 11 blood samples were withdrawn within 60 min. Plasma clearance was determined on the basis of a two-compartment model. Imaging was performed in the posterior projection by acquiring three sets of images. Extraction ratios were determined from the blood samples obtained from the renal vein and abdominal aorta. RESULTS: Renal clearance of 99mTc-EC was significantly lower than that of OIH (p = 0.0003) with good correlation (r = 0.93). Volume distributions of 99mTc-EC and OIH were 26584 +/- 10807 ml/1.73 m2 and 23148 +/- 7602 ml/1.73 m2, respectively (p = 0.047). The clearance half-lives of 99mTc-EC and OIH were 98 +/- 54 min and 74 +/- 54 min, respectively (p = 0.049). Protein binding of 99mTc-EC (33 +/- 3.2%) was significantly less than that of OIH (62 +/- 2.8%) (p < 0.0001). Red blood cell binding of 99mTc-EC was almost negligible (5.7 +/- 4.3%). Similar extraction ratios were obtained from blood (0.68 +/- 0.08) and plasma (0.70 +/- 0.07) (p = 0.062). The 60-min excretion fractions were similar for 99mTc-EC and OIH, with values of 50% +/- 20% and 51% +/- 19%, respectively (p = 0.9). CONCLUSION: Technetium-99m-EC is a suitable radiopharmaceutical for routine renal dynamic studies. Although the biological behavior of 99mTc-EC seems to be different from that of OIH, their clearances demonstrate high correlation. Technetium-99m-EC provides excellent quality images and has high potential in the evaluation of quantitative renal functions.

Adult↗
PubMed1995

Myocardial technetium-99m-teboroxime activity in acute coronary artery occlusion and reperfusion: relation to myocardial blood flow and viability.

UNLABELLED: The purpose of this study was to test the hypothesis that 99mTc-teboroxime retention within the heart depends at least in part on the presence of viable myocytes. METHODS: We used a porcine model of acute myocardial infarction with reperfusion and compared the myocardial uptake of labeled microspheres at 1 hr of reperfusion with that of 99mTc-teboroxime. Eleven domestic swine had measurements of hemodynamics and regional myocardial blood flow (microspheres) at baseline, at 10 and 50 min of left anterior descending (LAD) coronary artery occlusion and at 10 and 60 min of LAD reperfusion. Technetium-99m-teboroxime was injected intravenously at 60 min of reperfusion and the animal was killed 5-7 min later. The heart was then perfused with triphenyl tetrazolium chloride to identify infarcted and jeopardized myocardium in the occlusion zone and with Evans blue dye to mark normally perfused myocardium. After imaging, tissue sections were digested and colored microspheres were extracted and counted to determine myocardial blood flow. RESULTS: After coronary occlusion, infarct zone (MIZ) to normal zone (NZ) blood flow ratios declined from 0.95 +/- 0.27 (pre-occlusion) to 0.18 +/- 0.15 at 10 min and 0.25 +/- 0.35 at 50 min of occlusion (both p < 0.05). The MIZ:NZ count ratio at 60 min of reperfusion was less than the MIZ:NZ blood flow ratio in every animal and over the entire range of flow ratios (0.55-3.64). CONCLUSION: Technetium-99m-teboroxime requires viable myocytes for retention within the heart and is not exclusively a tracer of myocardial blood flow when imaged 5-7 min after injection. Additional in vivo imaging studies are required to determine the extent to which reduced retention of the tracer by reperfused but nonviable myocardium influences the appearance of clinical scans.

Animals↗
PubMed1994

Myocardial uptake and kinetic properties of technetium-99m-Q3 in dogs.

UNLABELLED: We postulated that 99mTc-Q3, a cationic imaging agent, produces myocardial activity related to myocardial blood flow during myocardial ischemia and pharmacologic coronary artery vasodilation, and shows little or no myocardial redistribution over 4 hr after intravenous injection. METHODS: In six Group 1 dogs, the chest was opened, the left circumflex coronary artery was acutely ligated, and dipyridamole (0.32, 0.56 or 0.84 mg/kg) was infused into the right atrium, followed by 10 mCi of 99mTc-Q3. Myocardial blood flow was measured by radiolabeled microspheres. The animals were euthanized and 357 myocardial samples were assayed in a well counter for 99mTc activity. One week later, radiolabeled microsphere activity was counted and myocardial blood flow calculated. In nine Group 2 dogs, a variable occluder was placed around the left circumflex coronary artery and an ischemic level of circumflex blood flow was maintained constant over 4 hr as measured by an ultrasonic flow meter. Dipyridamole (0.56 mg/kg) was then infused into the right atrium followed by 10 mCi of 99mTc-Q3. Gamma camera images were acquired at 5, 15, 30, 60, 120 and 240 min following 99mTc-Q3 injection. Microsphere blood flow and endocardial biopsies (n = 6 dogs) were performed at 30, 60, 120 and 240 min following 99mTc-Q3 injection. RESULTS: In the Group 1 animals, 99mTc activity (y) was related to myocardial blood flow (x) from 0 to 6.1 ml/min/g by the relationship y = 0.83X + 0.18, r = 0.95, p = 0.0001. The scintigraphic ratio of myocardial perfusion defect zone counts-to-normal myocardial zone counts (0.54 +/- 0.05 at 30 min) remained constant over 4 hr, as did technetium counts from direct endocardial sampling. Scintigraphic count ratios allowed discrimination between perfusion defect and normal myocardial regions beginning at 5 min following 99mTc-Q3 injection. CONCLUSIONS: Over a range of myocardial blood flows from 0 to 6.1 ml/min/g, 99mTc-Q3 myocardial activity is related to myocardial flow at the time of tracer injection. Technetium-99m-Q3 shows no evidence of myocardial redistribution over a 4-hr period.

Animals↗
PubMed1994

The accuracy of technetium-99m-labeled red cell scintigraphy in localizing gastrointestinal bleeding.

OBJECTIVE: To evaluate the success of technetium-99m-labeled red blood cell scintigraphy in localizing the site of gastrointestinal bleeding, and to identify the clinical and technical factors that contribute to scan accuracy. METHODS: A retrospective review was conducted of all patients who underwent a tagged red blood cell scan for the evaluation of gastrointestinal bleeding at our institution from 1981 to 1991. RESULTS: Of a total of 153 patients, 90 (59%) had positive scans, whereas, in 63 (41%), they were negative. Of the 90 patients who had positive scans, it was possible to assess scan accuracy in 44 who had corrective surgery or an additional diagnostic procedure which definitively localized the site of bleeding. Of those 44 patients, the correct bleeding site was identified by red blood cell scanning in 33 patients (75%) overall and in all six patients with a left colon bleeding site. In this group of 44 patients, 22 scans were positive within 2 h, and of these the scan was accurate in localizing the bleeding site in 19 of 22 (86%). When the three subjects with upper gastrointestinal bleeding were excluded, the scan was positive in 100% of the remaining 19 patients. CONCLUSION: The technetium-labeled red blood cell scan is a reliable tool for the assessment of unexplained lower gastrointestinal bleeding when the scan is positive within the first 2 h, and an upper gastrointestinal source has already been excluded.

Aged↗
PubMed1994

Technetium-99m-tetrofosmin to assess myocardial blood flow: experimental validation in an intact canine model of ischemia.

UNLABELLED: Technetium-99m-tetrofosmin is a 99mTc-labeled perfusion tracer demonstrating promise for myocardial perfusion imaging. To determine if 99mTc-tetrofosmin tracks myocardial flow over a pathophysiologic range, the initial myocardial uptake and clearance of 99mTc-tetrofosmin relative to microsphere flow were evaluated in a canine model of ischemia during pharmacological vasodilatation. METHODS: Six open-chest dogs were subjected to complete left anterior descending coronary artery occlusion. Dogs were injected with 99mTc-tetrofosmin and radiolabeled microspheres during pharmacological stress. Coincident with radiotracer injection, dynamic planar imaging and arterial sampling were performed to assess 99mTc-tetrofosmin clearance from blood, myocardium, lung and liver. Fifteen minutes after injection, hearts were excised for well counting of myocardial 99mTc-tetrofosmin activity and flow. RESULTS: Myocardial 99mTc-tetrofosmin activity correlated linearly with microsphere flow (r = 0.84). Relative 99mTc-tetrofosmin activity underestimated flow at higher flow ranges (> 2.0 ml/min/g) and overestimated flow in low flow ranges (< 0.2 ml/min/g). Technetium-99m-tetrofosmin cleared rapidly from the blood and was retained in the myocardium. Resting target-to-background activity ratios (heart:lung = 3.57 +/- 1.01; heart:liver = 0.58 +/- 0.04) were acceptable 10 min after injection. CONCLUSION: Our experimental data support both the validity of 99mTc-tetrofosmin as a myocardial perfusion tracer and the use of early poststress 99mTc-tetrofosmin imaging for the assessment of myocardial perfusion in man.

Adenosine↗
PubMed1994

Thrombus imaging with technetium-99m synthetic peptides based upon the binding domain of a monoclonal antibody to activated platelets.

UNLABELLED: Monoclonal antibodies which recognize fibrin or platelets have enabled imaging of vascular thrombi, however, early imaging has been difficult because of the slow blood disappearance of even small antibody fragments. It was theorized that it might be possible to synthesize peptides which possess the same thrombus affinity as monoclonal antibodies, but which would leave the blood pool much more rapidly. METHODS: In this study, peptides were synthesized with amino acid sequences based on the primary binding region of the platelet glycoprotein IIb/IIIa-directed monoclonal antibody PAC1. Both termini of the peptides were blocked to prevent rapid proteolysis and a metallothionein-derived sequence was incorporated as a chelating agent for reduced technetium. RESULTS: Technetium-99m-labeled peptides produced images of fresh clots in the jugular veins of rabbits and day-old thrombi in the femoral veins of dogs within 2 hr after injection. In control experiments, a 99mTc-labeled nonspecific peptide failed to produce focal images of thrombus. Another control compound, 99mTc-glucoheptonate, did produce images of fresh clots in rabbits but failed to produce focal images of day-old thrombi. As was hoped, blood clearance of the 99mTc peptides was rapid, with excretion through the kidneys, however, none of the peptides studied had better thrombus-to-blood ratios than iodinated fibrinogen and all had significantly lower deposition in the thrombus. CONCLUSION: Using labeled synthetic peptides appears to be technically feasible but the absolute binding to thrombus is not yet sufficient for reliable imaging of pre-existing thrombi.

Amino Acid Sequence↗
PubMed1993

Rapid back to back adenosine stress/rest technetium-99m teboroxime myocardial perfusion SPECT using a triple-detector camera.

Technetium-99m-teboroxime is characterized by a high extraction fraction over a wide range of blood flow rates, rapid myocardial clearance and avid hepatic uptake. This study determined the imaging parameters and examined the clinical efficacy of a rapid back to back adenosine stress/rest teboroxime myocardial perfusion SPECT protocol using a triple-detector camera. Acquisition parameters were determined using cardiac phantom studies which were then applied in SPECT studies of 51 catheterized patients (22 with prior myocardial infarction) and 20 patients with a "low" (7.9% +/- 4.3%) likelihood of coronary artery disease. Technetium-99m-teboroxime (20-25 mCi) was injected at the third minute of adenosine infusion. Teboroxime (20-25 mCi) was also injected at rest, 15 min later. Stress followed by rest SPECT were completed within 25 min using a triple-detector camera and sequential, 1-min continuous rotations in alternating directions. Summed raw data from the first to second (1-2 min), second to third (2-3 min) and second to fifth (2-5 min) minutes of imaging following stress teboroxime injection were reconstructed and compared for image quality, degree of liver interference, and accuracy for diagnostic efficacy. In a subgroup of 30 patients, 2-8-min summed images were also reconstructed to compare this more conventional imaging protocol with our rapid acquisition. Image quality was fair to good in 75% of the 1-2-min, 84% of the 2-3-min and 2-5-min studies and 53% of the 2-8-min scans. The frequency of severe liver interference appeared to increase with the duration of imaging time (1-2 min: 3%; 2-3 min: 7%; 2-5 min: 8%) and was greatest (30%, p = 0.08) with 2-8-min images. Three patients (4%) had uninterpretable studies due to intense hepatic uptake. Overall sensitivity (95%) and specificity (71%) were equal for the 2-3-min and 2-5-min stress images and appeared better than in the 1-2-min images (84% and 57%, respectively). For the 2-8-min scans, vessel sensitivity (69%) and specificity (63%) appeared poorer than with 2-3-min studies (83% and 81%, respectively). Normalcy rates were 89% for the 2-3-min and 2-5-min and 79% for 1-2-min images. The back to back adenosine stress/rest teboroxime SPECT can be performed in 30 min using a triple-detector camera. Although overall high sensitivity and normalcy rates were achieved, the protocol is technically demanding. Interference due to intense liver uptake remains problematic.

Adenosine↗
PubMed1993

Technetium-99m-1,2-bis[bis(2-ethoxyethyl) phosphino]ethane: human biodistribution, dosimetry and safety of a new myocardial perfusion imaging agent.

A novel 99mTc complex (1,2-bis[bis(2-ethoxyethyl)phosphino] ethane, 99mTc-tetrofosmin) has been developed to replace 201Tl in myocardial perfusion imaging. Biodistribution, safety and dosimetry of 99mTc-tetrofosmin were studied in 12 male volunteers, each at rest and during exercise. Safety parameters measured to 48 hr postinjection revealed no clinically significant long-term drug-related changes. Biodistribution was studied by acquiring whole-body or serial static images up to 48 hr postinjection. Technetium-99m-tetrofosmin shows good heart uptake (1.2%) with retention. Clearance is excellent from blood (< 5% by 10 min), liver (< 4.5% by 60 min) and lung. Sequestration of activity by skeletal muscle is enhanced during exercise. Radiation dosimetry calculations indicate that the effective dose, assuming a 3.5 hr bladder voiding period, is 32.9 x 10(-3) rad/mCi (8.9 x 10(-3) mSv/MBq) at rest and 26.7 x 10(-3) rad/mCi (7.1 x 10(-3) mSv/MBq) after exercise. Technetium-99m-tetrofosmin can produce high quality myocardial images from 5 min to several hours postinjection.

Heart↗
PubMed1995

Comparison of preoperative imaging techniques (thallium technetium scan and ultrasonography) and intraoperative staining (with methylene blue) in localizing the parathyroid glands.

We carried out a prospective study to compare the predictive value of preoperative thallium technetium scan, ultrasound (US) and intraoperative staining of the parathyroid glands (with methylene blue) in patients with parathyroid adenoma, parathyroid hyperplasia, thyroid carcinoma and thyrotoxicosis, in the Istanbul School of Medicine, Department of General Surgery. Methylene blue was given at a dose of 5 mg/kg/body weight in a 500 ml 5% Dextrose +0.9% saline solution 1 hour before surgery. All adenomas (10 patients), hyperplastic parathyroid glands (12 patients) and 45 of 52 suppressed glands (82%) were stained. In patients with thyroid carcinoma (7) and thyrotoxicosis (5), 42 of 48 normal parathyroid glands (87%) were stained. There were no maneuver-related complications. Thallium technetium scan (TT) accurately identified 10 of 10 (100%) parathyroid adenomas and 13 of 26 (50%) hyperplastic parathyroid glands. US successfully localized 10 of 10 (100%) adenomas and 18 of 26 (66%) hyperplastic glands. Neither technique was successful in identifying normal glands. The intraoperative identification of the parathyroid glands with methylene blue was found to be an effective, safe and cost-effective technique which helps the surgeon in the dissection and shows abnormal parathyroid glands more accurately than preoperative imaging techniques.

Adult↗
PubMed1997

Kinetics of technetium-99m-teboroxime in reperfused nonviable myocardium.

UNLABELLED: This study evaluates 99mTc-teboroxime uptake and clearance kinetics in reperfused infarcted myocardium. METHODS: In 47 isolated buffer perfused rat hearts, 17 had normal flow (Control), 13 had 30 min of no flow followed by reflow (Noflow30) and 11 had 60 min of no flow followed by reflow (Noflow60). A 1-hr uptake phase was begun by normally perfusing all 41 hearts with 99mTc-teboroxime-doped buffer. After uptake, a 1-hr clearance phase was begun by switching to a 99mTc-teboroxime-free buffer. Technetium-99m activity was monitored with a Nal probe. Triton X-100, a membrane detergent, was given after tracer loading to six additional hearts. RESULTS: Control and Noflow30 hearts showed near linear and rapid uptake, while Noflow60 hearts showed curvilinear and significantly less uptake than predicted. All three of these groups showed biexponential clearance. Early t1/2 was not significantly different for the three groups (Control = 6.3 +/- 1.9 sem min, Noflow30 = 5.4 +/- 1.3 min, Noflow60 = 8.9 +/- 2.8 min). Late t1/2 was significantly shorter for Noflow30 (52.3 +/- 5.3 min) and the Noflow60 (50.9 +/- 4.3 min), compared to the Control hearts (74.1 +/- 6.6 min, p < 0.05). One-hour fractional clearances were significantly greater for the Noflow30 and Noflow60 hearts (0.65 +/- 0.01 and 0.65 +/- 0.01, respectively) compared to the Controls (0.55 +/- 0.01, p < 0.05). In hearts given Triton X-100, there was a markedly increased fractional clearance of 0.96 +/- 0.01 (p < 0.01 compared to Controls). Electron microscopy showed evidence of mild injury in the Noflow30 hearts, more extensive damage in the Noflow60 hearts and severe irreversible injury in Triton X-100 hearts. CONCLUSION: Myocardial 99mTc-teboroxime uptake and clearance kinetics are significantly altered in mildly and moderately injured reperfused myocardium. Technetium-99m-teboroxime clearance is markedly accelerated in the setting of overt damage to cell and organelle membranes induced by Triton X-100.

Analysis of Variance↗