Quality of bone scans compared with time between dose and scan.

The usual time interval between the administration of technetium-labeled bone-seeking radiopharmaceuticals and imaging varies among nuclear-medical departments. Pharmacokinetic data indicate that the interval could be as short as 2 hr. We have studied overall quality of bone detail in 280 bone scans performed at intervals varying from 2 to 5 hr following injection of technetium-99m diphosphonate. No significant qualitative difference was found between the studies performed at 2 hr and those done at later intervals.

Accumulation of 99mTc-diphosphonate in four patients with hepatic neoplasm: case reports.

The accumulation of bone-seeking radiopharmaceuticals in extraosseous lesions has been reported in patients with myocardial infarctions, cerebral infarctions, and some soft-tissue tumors. While the precise mechanisms involved remain uncertain, the spectrum of abnormalities exhibiting such accumulation increases. In our laboratory, 99mTc-diphosphonate concentrated in four hepatic tumors (one cholangiocarcinoma and three metastases from colon carcinoma). This property of phosphate-related radiopharmaceuticals has not been reported previously. Awareness of the possibility of focal diphosphonate accumulation in the liver should help avoid confusion with right lower rib-cage metastasis or pleural effusion.

Improvement in visualization of hepatic lesions with upright views.

Standing scintiphoto views of the liver may provide improved visualization as compared with conventional supine liver images. This is partially due to decreased respiratory motion of the liver. The standing position is recommended if the supine liver scan appears normal in a patient suspected of metastatic disease.

Pharmacokinetics of technetium-99m diphosphonate.

Increased diagnostic information may be derived with Tc-99m diphosphonate from a detailed kinetic analysis of blood disappearance, urinary excretion, and quantitative assessment of skeletal uptake. Blood and urine determinations were studied in three populations: normal volunteers, patients with negative bone scans, and patients with positive bone scans. Quantitative imaging studies were performed in normal volunteers and patients with a scintillation camera interfaced to a computer. All subjects were scanned in the lower lumbar region up to 1 hr after Tc-99m diphosphonate administration. Blood levels exhibited a triexponential clearance pattern. Significant (p less than 0.05) differences were observed for the 5-min blood and 0-1 hr urine values among the various groups. The computer-generated images showed an initial early uptake in bone, kidneys and soft tissue. Thereafter, a parallel fall-off in activity was observed in kidney and soft tissue, with a concomitant increase in bone. Skeletal uptake was different for normal and diseased bone.

The diagnosis of acute complicated cholecystitis by Tc-99m sulfur colloid liver imaging.

Increased hepatic activity surrounding the gallbladder fossa during Tc-99m SC liver imaging was observed. Subsequent Tc-99m IDA biliary imaging showed similar findings in the face of nonvisualization of the gallbladder--the classic "rim sign." Surgery confirmed the diagnosis of complicated acute cholecystitis. This case indicates that a rim sign may be seen with either Tc-99m SC or Tc-99m IDA imaging and may have the same diagnostic significance in both.