P-GLYCOPROTEIN EXPRESSION BY TECHNETIUM-99M-MIBI SCINTIGRAPHY IN HEMATOLOGIC MALIGNANCY

Our aim was to ascertain the relationship between the degree of Tc-99m -MIBI uptake and the level of p-glycoprotein (Pgp) expression determin ed by flow cytometry and reverse transcription-polymerase chain reacti on (RT-PCR) techniques in patients with hematologic malignancy. Method s: A total of 21 samples (19 patients) were evaluated. Two patients ha d repeat studies after therapy. Thirteen samples were studied at the t ime of initial diagnosis and 8 during relapse after therapy. After MIB I imaging, either bone marrow aspiration or peripheral blood was obtai ned for flow cytometric and RT-PCR analyses, Flow cytometry was perfor med using two different antibodies. After the injection of 555 MBq MIB I, whole-body and pelvic spot images were acquired using a dual-head g amma camera, The uptake in the bone marrow was evaluated against the b ackground (adjacent soft tissue) by both qualitative (scoring system) and quantitative (tm/bkg ratios) analyses, Results: For flow cytometry , the limit for Pgp overexpression was set at >15% Pgp-positive mononu clear bone marrow or peripheral blood cells. There was an inverse corr elation between the levels of Pgp and MIBI imaging using both the qual itative (scoring system) and quantitative (tm/bkg ratios) analyses (p = 0.022), Mean values were statistically different between Pgp + and P gp - groups for both qualitative and quantitative analyses (p = 0.009 and 0.024, respectively). For RT-PCR, there was statistical support to ward a difference in the mean values between Pgp + and Pgp - groups by qualitative analysis (p = 0.061); however, no statistical difference was found between these two groups by quantitative analysis (p = 0.179 ), Conclusion: Based on the strong correlation between the imaging and flow cytometry and a statistical support toward the correlation betwe en the imaging and RT-PCR, MIBI imaging may be used for the in vivo de tection of Pgp in patients with hematologic malignancy.