Double-phase Tc-99m sestamibi scintimammography to assess angiogenesis andP-glycoprotein expression in patients with untreated breast cancer

This study evaluated the relation of Tc-99m sestamibi (MIBI) uptake and was hout in untreated breast cancer with immunohistochemically determined angio genesis and P-glycoprotein expression. Thirty-one patients with untreated b reast cancer were studied prospectively. Tc-99m MIBI scintigraphy and immun ohistochemical analyses of angiogenesis and P-glycoprotein expression were used to evaluate surgically removed tumor tissues. Anterior and both latera l planar images were acquired 10 and 180 minutes after intravenous injectio n of 740 MBq (20 mCi) Tc-99m MIBI. The tumor-to-normal breast ratio (T:N) a nd washout index (early T:N - late T:N divided by early T:N) were calculate d. A significant correlation was found between angiogenesis and T:N at earl y and late images. Pearson's correlation coefficients and probability value s were r = 0.54, P = 0.002 at early images and r = 0.47, P = 0.008 at late images. The T:N of both early and late images were not different among diff erent groups of P-glycoprotein expression (P = 0.367 and P = 0.113, respect ively), although the washout index was significantly different among the gr oups (P = 0.001), A strong correlation was found between the washout index and P-glycoprotein expression (r = 0.67, P < 0.01). Double-phase scintimamm ography to assess the early tumoral uptake and washout of Tc-99m MIBI can b e used as a simple functional test for in vivo imaging of tumoral angiogene sis and P-glycoprotein expression in patients with untreated breast cancer.