 A "biopsy" is a small piece of tissue removed primarily for the purposes of surgical pathology analysis, most often in order to render a definitive diagnosis.Types of biopsies include "core biopsies", which are obtained through the use of large-bore needles, sometimes under the guidance of radiological techniques such as ultrasound, CT scan, or magnetic resonance imaging.Core biopsies, which preserve tissue architecture, should not be confused with fine-needle aspiration specimens, which are analyzed using cytopathology techniques.