TCPDF中的writehtmlcell上的错误图像位置

When I generate an PDF, I use Emoji Icons. This works fine, the Emoji's are between chars and words. But the position is bad.

Example:

enter image description here

<img src="emoji/Emoji173.png" width="18" height="18" border="0" style="margin-bottom: -4px" />

The Style -> style="margin-bottom: -4px" -> does not work. :-(

Have someone an idea to set the icon lower?