Quantitative videodensitometric technique for verification of optimal coronary stent implantation

Coronary angiography is not sensitive enough to define the results of stent implantation. Intravascular ultrasound defines accurately the anatomy of the vessel and the stent within the vessel and is thus considered the gold standard for defining the results of stent implantation. However intravascular ultrasound is an additional invasive procedure that is time consuming and expensive. This study describes a new simple quantitative videodensitometric technique, developed specifically to assess the results of stent implantation and compares the findings to intravascular ultrasound. In the proposed algorithm for the videodensitometric analysis, density profiles were constructed perpendicular to the long axis of the stented segment and each one was compared (after background subtraction) with a theoretic profile of a normal artery at that location. Density deficit index was determined at each point from the actual and theoretic profiles and a global volumetric density deficit index was calculated for each stent by integrating the deficit indices at all points along the stent. Similarly an area stenosis was determined at each point along the stent (using the stent and normal vessel cross sectional areas as defined by intravascular ultrasound) and the global volumetric stent stenosis was calculated by integrating the values of area stenosis along the stent. Twenty-five patients were evaluated immediately before and after coronary stent implantation. Global density deficit index improved from 66.1+/-16.4% before (after last balloon inflation) to 44.4+/-11.1% after stenting (P < 0.001). The shape of the curves of densitometric deficit indices along each stent were similar to the equivalent area stenosis curves as determined by intravascular ultrasound. The correlation (R = 0.74) between the global volumetric density deficit index and the global volumetric stent stenosis is statistically significant (P < 0.001). In conclusion, in this preliminary report we describe a new algorithm for videodensitometric analysis of the results of coronary stent implantation. As compared with intravascular ultrasound this method does not require an additional invasive procedure and it is quick cheap and easy to carry out.