Put an image in the center of a cell with migradoc

row.Cells[0].Format.Alignment = ParagraphAlignment.Center;
row.Cells[0].VerticalAlignment = VerticalAlignment.Center;

You might need to add a paragraph to the cell, set the alignment on the paragraph, and then add the image to the paragraph.

row.Cells[0].Format.Alignment = ParagraphAlignment.Center;
row.Cells[0].VerticalAlignment = VerticalAlignment.Center;
row.Cells[0].AddParagraph().AddImage(imageLocation);