ABSTRACT
The effect of cimetidine, an H2-receptor blocking agent, on the secretion of 99mTc-pertechnetate was studied in 11 dogs. In cimetidine-treated animals, there was increased retention of 99mTc-pertechnetate by the gastric wall as compared with the untreated animals. The results indicate the potential use of cimetidine for enhanced visualization of Meckel's diverticulum, Barrett's esophagus, and the stomach, with 99mTc-pertechnetate.
Subject(s)
Cimetidine/pharmacology , Gastric Mucosa/metabolism , Guanidines/pharmacology , Animals , DogsABSTRACT
Experiments were performed in 14 dogs to study the effect of changes in bone blood flow on the tibial uptake of the skeletal tracer Tc-99m(Sn)methylenediphosphonate (Tc-99m MDP). Aortic blood was diverted through a pulsatile-flow pump in order to monitor and control femoral arterial blood flow. Tibial nutrient perfusion, as measured with labeled microspheres, paralleled the changes in arterial flow. We found that increments in bone blood flow up to four times normal produced only minimal augmentation of Tc-99m MDP uptake (mean = 33%), a markedly nonproportional relationship. The data points clustered about a predicted curve produced by perturbing the rate constants of a seven-compartment model obtained in normal dogs. These findings indicate that bone uptake of Tc-99m MDP is diffusion-limited, and they therefore cast doubt upon the validity of a method used for many years for estimating bone blood flow, the so-called skeletal tracer clearance technique. Nerve section, performed in 14 other dogs, augmented Tc-99m MDP uptake by about 50% at supranormal flows, suggesting a parallel-flow model of the microcirculation in bone, under sympathetic control. Such a model satisfactorily explains many scintigraphic findings in disease states.
Subject(s)
Bone and Bones/metabolism , Diphosphonates , Technetium Tc 99m Medronate , Technetium , Tin , Animals , Bone and Bones/blood supply , Diphosphonates/metabolism , Dogs , Femoral Artery/physiology , Femoral Nerve/physiology , Regional Blood Flow , Sciatic Nerve/physiology , Technetium/metabolism , Tibia/blood supply , Tibia/metabolism , Tin/metabolismABSTRACT
The bone scan appearance of hypertrophic pulmonary osteoarthropathy (HPO) in patients with pulmonary neoplasms and a variety of other lesions has been described by several investigators. It is well known that after therapy, the bone scan changes resolve. This report deals with a patient who had no therapy for a pulmonary neoplasm. In a study done three months later, changes in his initial bone scan that had suggested pulmonary osteoarthropathy had resolved completely, even though the patient had no treatment for his carcinoma.
