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Rheumatoid arthritis (RA) is a joint disease characterized by inflammation of the joints, stiffness, swelling, overgrowth of the cartilage tissue, and pain. The extent of inflammation in an arthritic joint can be indicated by the degree of swelling and warmth. Because these sensations tend to be subjective, the relation between pain perceived by the patient and inflammation is poorly defined. In rheumatoid arthritis, the synovial fluid in the joint contains increased numbers of neutrophils, a type of white blood cell. Studies suggest that neutrophils may release highly reactive elements, such as enzymes and oxygen radicals, that are capable of destroying joint tissue. In addition, neutrophils may release substances, such as prostaglandins and bradykinin, that may cause pain. Studies have shown a correlation between the movement of neutrophils and the degree of pain. The migration of neutrophils in the knees of patients with RA and osteoarthritis, a chronic joint disease, was assessed by labeling the neutrophils with a radioactive marker. Patients with RA exhibited significant neutrophil migration, which was reduced by 60 percent after injection of anti-inflammatory steroids into the joint. The decrease in neutrophil migration coincided with a reduction in pain. The migration of leukocytes (white blood cells) was also detected in patients with osteoarthritis but not patients with RA. The findings show that radioactive labeling of neutrophils is a sensitive method for assessing neutrophil-induced inflammation in the joints of patients with RA. (Consumer Summary produced by Reliance Medical Information, Inc.)

A simplified technique of labelling leucocytes with technetium-99m is described and applied to patients with active rheumatoid arthritis. The clinically active and less active knees in seven patients were imaged and the uptake of labelled leucocytes was measured. The measurements were repeated after local steroid injection into nine painful knees. A 50–80 reduction in leucocyte uptake localized to the region of the synovium was demonstrated in the eight knees which showed clinical responses and a rise of 8 in the non-responder. There was a variable response in the knees that were not injected. 99Tcmleucocyte imaging in rheumatoid arthritis is able to assess objectively joint inflammation and its response to treatment.

The preparation, application and clinical usage of 99mTc-mercaptoacetyltriglycine, MAG3, a tubular secreted compound, is described in the first 225 patients in a phase III study. Image quality, relative renal function, and renal transit times were compared with a 4 fold greater administered activity of 99mTc-DTPA in 11 patients. Correlation coefficients of 0.94 for relative function, 0.83 for parenchymal transit time index and 0.82 for whole kidney transit time index were found. Frusemide responses were similar. 99mTc-MAG3 is an efficacious radiopharmaceutical for routine renal radionuclide studies, giving excellent image quality in patients with hypertension, poor renal function, obstructive nephropathy or a renal transplant.