A biopsy grid is provided that is useful in medical imaging. The biopsy grid comprises a hydrogel layer containing a mixture of contrast agents that are visible in images from X-ray, CT scans, MRI, and/or positron emission tomographs. The hydrogel mixture is attached to a frame having a silicone coated release liner and an adhesive layer. The hydrogel layer is cut into strips that serve as markers in an image. The biopsy grid can be used to locate the position of the marker relative to a tissue of interest in a medical image.