The purpose of the study was threefold: (1) to evaluate the efficacy of an 111In-labeled murine monoclonal antibody (ZME-018) directed against a heavy molecular weight melanoma associated glycoprotein in localizing metastatic disease; (2) to determine the effect of unlabeled antibody mass (2.5, 5, 10, 20, and 40 mg) on labeled antibody blood clearance, biodistribution and lesion detection; (3) to estimate radiation dosimetry. Twenty-five patients with previously documented disease received an intravenous infusion of 2.5 to 40 mg of monoclonal antibody with 1 mg of the antibody labeled with 5 mCi of 111In. There were no acute reactions. Patients were scanned without computer enhancement or background subtraction techniques at 24 and 72 hr after injection. Imaging detected tumor in 14/18 (78%) patients with active disease, identified 24/44 (77%) of lesions greater than 1 cm and changed or specifically directed patient management in 22% (4/18) patients with tumor. There was a prolongation in blood clearance associated with decreased liver and spleen activity following administration of 20 and 40 mg of antibody compared to the three lower antibody dose levels. Assuming a biodistribution similar to [111In]ZME-018, the radiation dose delivered to normal tissues by [90Y]ZME-018 would restrict its use as a routine vehicle for radioimmunotherapy; however, it may be possible to deliver substantial tumor doses in selected patients.

Animal studies suggest that the N/sub 3/S ligand, Tc-99m mercaptoacetyltriglycine (MAG/sub 3/) may provide a satisfactory Tc-99m replacement for I-131 hippurate (OIH). The ligand avoids the problem of stereo isomers and can be prepared in kit form. Tc-99m MAG/sub 3/ (10 mCi) and OIH (300 ..mu..Ci) studies were performed in 10 normal volunteers and 8 patients to compare the image quality, renal excretion, blood clearance, and time to peak height of the renogram curve. Serum creatinines in the 8 patients ranged from 1.6-9.8 mg/dl. Blood clearance data were obtained in 7 volunteers and 5 patients. Tc-99m MAG/sub 3/ was cleared more rapidly than OIH with a mean clearance of 1.30 L/min compared to .88 L/min for OIH. In the patients, MAG/sub 3/ had a mean clearance of .44 L/min versus .43 L/min for OIH. Thirty minute urine collections obtained from 3 of 8 patients showed no difference in the excretion of MAG/sub 3/ and OIH. There was no significant difference in the time to peak height for MAG/sub 3/ and OIH in either the volunteers or patients. In all subjects, the quality of the Tc-99m MAG/sub 3/ images was clearly superior to OIH. In summary, preliminary results suggest that Tc-99mmore » MAG/sub 3/ may be a potential replacement for OIH and further clinical evaluation is warranted.« less

Because of the normal hepatic and splenic accumulation of 111In labeled leukocytes, the detection of upper quadrant abscesses can be difficult. A prospective study was undertaken to determine if the addition of 99mTc SC liver-spleen scanning to 111In leukocyte imaging would increase diagnostic accuracy. 44 consecutive patients with suspected abdominal abscess underwent a total of 71 combined 99mTc SC liver-spleen/111In leukocyte scans. Standard abdominal imaging was performed 24 hours after injection of 111In labeled leukocytes. Immediately thereafter, 5 mCi 99mTc SC was injected intravenously and standard liver-spleen scan was done in the exact same projections. Computer subtraction of the liver-spleen image from the leukocyte image in the same projection was also performed. Scans were evaluated by two independent observers without knowledge of the clinical diagnosis. 26 studies had proven abscesses, 15 of which involved the upper abdomen. In 17% of studies (47% of patients with upper quadrant abscesses) the liver-spleen scan was essential in diagnosing or excluding the diagnosis of upper abdominal abscess. In an additional 7% of the studies, the liver-spleen scan was necessary to define the extent of abscess and the surgical approach. 34% had additional abnormalities including hepatomegaly, splenomegaly, hepatocellular disease, transplant rejection and avascular necrosis of the femoral head. In 42% of cases, the liver-spleen scan did not contribute any additional information. We conclude that combined 99mTc SC liver-spleen and 111In leukocyte imaging is of significant benefit in the evaluation of patients with suspected abdominal abscesses.