Quantitative simultaneous In-111/Tc-99m planar imaging in a long-bone infection phantom.
In-111-white-blood-cell and Tc-99m-sulfur-colloid dual-radionuclide imaging are frequently utilized in the evaluation of patients with suspected osteomyelitis. We have developed a quantitative planar imaging method in which Tc-99m and In-111 scans are acquired simultaneously in accurate spatial registration. Long, thin tubes containing only In-111 or Tc-99m were first imaged in a list mode within a water bath inclined with respect to the water surface; from these, 12 energy spectra corresponding to different Tc/In ratios were synthesized. Triple-energy-window (TEW) parameters for scatter and radionuclide crosstalk correction, including scatter windows and weights, were optimized using 100 noise realizations of each of the spectra (1200 total). A long-bone phantom containing a simulated infection site was then imaged in water with five In/Tc ratios; 100 noise realizations of two conjugate-view images were generated from each acquisition (500 total). Two regions of interest (ROIs) were defined, and the ratio of In/Tc count ratios in these two ROIs was evaluated with and without the TEW scatter correction and geometric mean attenuation compensation. The average bias improved from 17.2% to 5.3%, with comparable precision. TEW corrections with non-optimized but practical energy windows also improved the bias to 6.4%. Compared with subjective visual assessment, quantitation of In-111/Tc-99m ratios may improve diagnostic accuracy and could eventually permit grading of osteomyelitis.
Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
Xuping
X
Zhu
Mi-Ae
MA
Park
Victor H
VH
Gerbaudo
Stephen C
SC
Moore
D016477:Artifacts; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology; D004735:Energy Transfer; D005121:Extremities / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007205:Indium Radioisotopes / Q000493:pharmacokinetics; D007962:Leukocytes / Q000000981:diagnostic imaging / Q000473:pathology; D010019:Osteomyelitis / Q000000981:diagnostic imaging* / Q000473:pathology; D019047:Phantoms, Imaging; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012542:Scattering, Radiation; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique; D013671:Technetium Tc 99m Sulfur Colloid / Q000493:pharmacokinetics
D007205:Indium Radioisotopes; D019275:Radiopharmaceuticals; D013671:Technetium Tc 99m Sulfur Colloid