sodium-pertechnetate-tc-99m and Ischemia

P-selectin expression is involved in the pathophysiology of biologically active arterial thrombus and endothelial activation after a transient ischemic event. Fucoidan is a polysaccharidic ligand of P-selectin, with a nanomolar affinity. In the present study, we propose a new approach of P-selectin molecular imaging based on radiolabeled fucoidan.. Two kinds of experimental models were selected to evaluate the ability of radiolabeled fucoidan to detect P-selectin expression: platelet-rich arterial thrombi (vegetations of infective endocarditis and arterial mural thrombus) and myocardial ischemia-reperfusion. These 2 settings were chosen because they were clinically relevant, and both were associated with an important overexpression of platelet and endothelial P-selectin, respectively.. (99m)Tc-fucoidan SPECT was able to detect the presence of platelet-rich arterial thrombi in all animals, with a median target-to-background ratio of 5.2 in vegetations of endocarditis and 3.6 in mural aneurysmal thrombus, and to detect a persistent endothelial activation at 2 h after reperfusion. In this latter model, the magnitude of the signal was correlated with the extent of myocardium that underwent transient ischemia. The sensitivity of selectivity of the uptake and retention of (99m)Tc-fucoidan in both settings was excellent.. This study supports (99m)Tc-fucoidan as a relevant imaging agent for in vivo detection of biologic activities associated with P-selectin overexpression, such as arterial thrombus and ischemic memory. Given the reported wide availability at a low cost, and its low toxicity, fucoidan seems to overcome some of the limitations of previous P-selectin-targeted imaging agents.

Topics: Animals; Annexin A5; Aortic Aneurysm, Abdominal; Aortic Valve; Autoradiography; Blood Platelets; Endocarditis, Bacterial; Endothelium, Vascular; Immunohistochemistry; In Vitro Techniques; Ischemia; Isotope Labeling; Male; P-Selectin; Polysaccharides; Radiopharmaceuticals; Rats; Rats, Inbred Lew; Rats, Wistar; Reperfusion Injury; Sodium Pertechnetate Tc 99m; Thrombosis; Tissue Distribution; Tomography, Emission-Computed, Single-Photon

Although the vascular pathology of carotid arteries is widespread, the function of salivary glands in reduced arterial flow conditions is not much investigated clinically and in experiments. At the same time blood supply is a keystone to normal functioning of every organ and especially of salivary secretion. The aim of this study was to estimate functional activity of salivary glands in reduced and restored blood supply conditions in experiment by sialoscintigraphy which is an approved method for functional assessment of salivary glands.. The ligature of a. carotis communis dextra was performed on 20 Californian rabbits. After 28 days sialoscintigraphy with Tc99 pertechnetate and revascularization through resection of the occluded part of a. carotis communis and reconstruction with venous autograft was performed. One month later sialoscintigraphy was done.. The functional activity of rabbit salivary glands after the ligature of a. carotis communis is strongly depressed. The revascularized glands accumulated isotope slowly, but the level of accumulation was higher than on the control side.. The ligature and reconstruction of a common carotid artery on rabbits confirm the important role of the arterial blood supply in functional activity of salivary glands and may be an appropriate experimental model for investigation of ischemic disease of salivary glands.

Topics: Anastomosis, Surgical; Animals; Carotid Artery Thrombosis; Carotid Artery, Common; Ischemia; Jugular Veins; Ligation; Male; Plastic Surgery Procedures; Rabbits; Radionuclide Imaging; Radiopharmaceuticals; Regional Blood Flow; Salivary Glands; Secretory Rate; Sodium Pertechnetate Tc 99m; Time Factors

To assess whether myocardial stunning occurs following brief episodes of effort ischemia, ventricular function was assessed by radionuclide angiography in 29 patients with coronary artery disease. No patient had evidence of previous myocardial infarction. Patients were divided into two groups according to presence of single (14 patients, Group 1) or multi-vessel (15 patients, Group 2) coronary artery disease. Equilibrium radionuclide angiocardiography was performed in the left anterior oblique projection by a small field-of-view gamma-camera. Acquisition were performed at baseline, at peak exercise, then again at 1 and 5 minutes of the recovery phase. For each acquisition, ejection fraction, peak filling rate and wall motion index were measured and compared. No difference in baseline and stress measurements was found between Group 1 and Group 2, except for the wall motion index that was more impaired during ischemia in patients of Group 2. Global and regional indexes of ventricular function did not show significant differences also in the two recovery periods when compared to the relative baseline values. Transient ischemia caused by an increase of oxygen demand did not reproduce the phenomenon of systolic and diastolic stunning observed in animal experiments, although in all patients the ischemia was of sufficient duration and severity to induce transient ventricular dysfunction.

Topics: Adult; Aged; Female; Humans; Ischemia; Male; Middle Aged; Myocardial Stunning; Physical Exertion; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Ventricular Function, Left

A nuclear imaging technique of the stomach, using technetium pertechnetate (99mTcO4), was evaluated in healthy dogs. The stomach was first insufflated with room air, then filled with barium sulfate to induce mild distention, outlining the gastric wall. Six dogs were imaged twice: initially without use of drugs that might affect gastric secretion of 99mTcO4, then after pretreatment with cimetidine and glycopyrrolate. These scans established the appearance of the normal (control) stomach and compared the quality of the image in the same dogs not pretreated, then pretreated with cimetidine and glycopyrrolate before administration of 99mTcO4. Avascular defects were then surgically created on the greater curvature of the stomach of the same 6 dogs, and gastroscintigraphy was performed in similar manner. Significant (P less than 0.05) quantitative differences were detected in the gastric images for scans of the avascular area, compared with various control scans. Qualitative assessment had overall accuracy of 90.28%. Results of the study reported here indicate that nuclear imaging can be a valuable diagnostic technique for detecting ischemic areas in the gastric wall of dogs.

Topics: Animals; Diagnosis, Computer-Assisted; Dog Diseases; Dogs; Ischemia; Multivariate Analysis; Predictive Value of Tests; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Stomach

Skin blood flow as reflected by the clearance rate of intradermal injections of Technetium-99m (99mTc) was studied in the skin of human volunteers and in a variety of clinical situations. In volunteers comparisons between the effect on clearance following intradermal injections of either lignocaine or lignocaine/adrenaline showed that the latter resulted in a dramatic reduction in the clearance rate of the technetium isotope and that such clearance curves exhibited no fast component. Clinical studies in grossly ischaemic skin revealed a similar absence of the fast component of isotope clearance and this was also the case for healed split thickness skin grafts. The dermal isotope clearance was also used in pedicle skin flaps both before and after clamping the axial pedicle in order to derive clearance ratios which would reflect the degree of neovascularisation to the flap. These preliminary observations suggest that the technique is safe, and easy to use in many clinical circumstances. We consider that it offers a valuable method by which changes in dermal blood flow may be quantified, when simultaneous control areas of isotope clearance are also studied. Suggestions are made for further avenues of study.

Topics: Adult; Aged; Humans; Ischemia; Male; Skin; Sodium Pertechnetate Tc 99m; Surgical Flaps

At below-knee amputation for arterial insufficiency in 31 patients, the muscle blood flow of quadriceps and triceps surae was measured by clearance of 99mTc pertechnetate pre- and postoperatively. In 15 patients, myoplastic amputation was performed and in 16 patients the medullary cavity of the tibial stump was plugged with cortex of the removed bone as well. Plugging caused a two-third increase in muscle blood flow.

Topics: Aged; Amputation Stumps; Amputation, Surgical; Arterial Occlusive Diseases; Blood Flow Velocity; Humans; Ischemia; Leg; Middle Aged; Muscles; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Tibia

Topics: Adult; Aged; Female; Humans; Ischemia; Leg; Male; Middle Aged; Radioisotopes; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium; Thallium

By means of a tracer technique with 99mTc-pertechnetate, provided with seven zonal regions of interest, 6 mm in width, placed at equal spaces of 18 mm, from the toe tip to the midfoot at a right angle to the long axis of the foot, arterial flow velocity in the foot during reactive hyperemia was measured. The mean velocity in the foot was 5.66 +/- 1.78 cm/sec in 14 normal limbs, 1.58 +/- 1.07 cm/sec in 29 limbs with distal thromboangiitis obliterans (TAO), 0.89 +/- 0.61 cm/sec in 13 limbs with proximal TAO, and 0.97 +/- 0.85 cm/sec in 15 limbs with arteriosclerosis obliterans (ASO). The velocity returned to normal in all 12 limbs after successful arterial reconstruction, whereas the foot or toe blood pressure remained pathologic in 9 of the 12 limbs postoperatively; the velocity reverted to normal in 4 of 13 limbs after lumbar sympathectomy. When the velocity was normalized after operation, the ulceration healed favorably, and the ischemic limb was salvaged. The most characteristic feature of peripheral arterial occlusive disease of the lower extremity was a stagnation of arterial circulation in the foot, and the flow velocity in the foot was a sensitive predictive index of limb salvage.

Topics: Adult; Aged; Arteriosclerosis Obliterans; Blood Flow Velocity; Blood Pressure; Female; Foot; Humans; Ischemia; Male; Middle Aged; Regional Blood Flow; Sodium Pertechnetate Tc 99m; Technetium; Thromboangiitis Obliterans; Vascular Surgical Procedures