Correlation between 99mTc-MIBI uptake and angiogenesis in MIBI-positive breast lesions

This study was undertaken to assess the correlation between the degree of accumulation and the washout of 99m technetium methoxyisobutylisonitrile (99mTc-MIBI) and angiogenesis in MIBI-positive breast lesions. Twenty-eight patients (mean age, 51±11 years) with 31 breast lesions who underwent scintimammography were studied. Anterior, left and right prone lateral images were obtained 20 min and 3 h after the injection of 740 MBq 99mTc-MIBI. All breast lesions showed increased 99mTc-MIBI uptake. Early and delayed tumor to background activity ratios (T/BG) and washout index (early tumor uptake−delayed tumor uptake divided by early tumor uptake) were calculated. Vascular endothelium was immunohistochemically labeled using a biotinylated monoclonal antibody directed against the factor-VIII-associated antigen using standard biotin-avidin technique. Angiogenesis was evaluated by assessing the vascular surface density (VSD) and the microvessel number (NVES) within 10 randomly chosen areas. All pathological data were compared with early and delayed T/BG activity ratios and washout index of 99mTc-MIBI. Statistical analysis was performed using Spearman correlation test. There was no statistically significant correlation between the degree of angiogenesis and early T/BG (r=.287, P>.05 with VSD, r=.351, P>.05 with NVES), delayed T/BG (r=.277, P>.05 with VSD, r=.315, P>.05 with NVES) and the washout index (r=.268, P>.05 with VSD, r=.285, P>.05 with NVES) of 99mTc-MIBI in all breast lesions. There was no statistically significant correlation between the degree of angiogenesis and early T/BG (r=.235, P>.05 with VSD, r=.356, P>.05 with NVES), delayed T/BG (r=.181, P>.05 with VSD, r=.285, P>.05 with NVES) and the washout index (r=.158, P>.05 with VSD, r=.187, P>.05 with NVES) of 99mTc-MIBI in 24 invasive breast lesions. No statistically significant correlation was found between the degree of angiogenesis and early T/BG (r=−.036, P>.05 with VSD, r=−.107, P>.05 with NVES), delayed T/BG (r=−.500, P>.05 with VSD, r=−.429, P>.05 with NVES), but there was a high correlation between angiogenesis and the washout index (r=.893, P<.05 with VSD, r=.964, P<.05 with NVES) of 99mTc-MIBI in seven noninvasive breast lesions. Amount of 99mTc-MIBI uptake in breast lesions is dependent on several factors. Our study indicates that early and delayed 99mTc-MIBI uptakes in MIBI-positive breast lesions are not related to angiogenesis in both invasive and noninvasive breast lesions. But washout index of 99mTc-MIBI in noninvasive breast lesions is highly correlated with angiogenesis. 99mTc-MIBI scintigraphy does not seem to be able to indicate angiogenic property of invasive breast lesions.