:thumbsup:
I could solve it:
Excel.Range oRange = (Excel.Range)xlWorkSheet1.Cells[Row, 1];
float Left =(float) ((double)oRange.Left);
float Top =(float) ((double)oRange.Top);
const float ImageSize=32;
xlWorkSheet1.Shapes.AddPicture(imagString, Microsoft.Office.Core.MsoTriState.msoFalse, Microsoft.Office.Core.MsoTriState.msoCTrue, Left, Top, ImageSize, ImageSize);
oRange.RowHeight = ImageSize + 2;