It is known to acquire one or more samples of tissue when particular localized medical problems are suspected, in order to test such samples and determine whether or to what extent a problem exists. For example, if a physician discovers a growth within soft tissue of a patient and wishes to test whether it is benign or cancerous, a deep biopsy sample of the soft tissue can be acquired. For such cases, biopsy devices have been developed that can be passed through skin, muscle and/or other tissues or body-walls and into the area of tissue of concern to the physician. The device's distal end cuts out a sample, e.g. a “core-sample,” of the suspicious tissue.
Various forms of existing biopsy devices use a moving mandrel or cannula that facilitates movement through tissue and cutting of a sample from surrounding tissue, so that the sample may be withdrawn with the device. A quick, longitudinal movement of a cannula, for example, is generally used to cut through tissue faster than the tissue can be moved forward or out of the way by the device. Depending on the particular type of device, problems that exist with such biopsy devices can include an inability to obtain a full core of tissue. For instance, a stylet or cannula may shoot forward beyond the tissue of interest or other sampling area, or may cut only a portion of a cylinder, thus not providing a full 360-degree sample. A full core of tissue has advantages over smaller or more-limited samples in providing sufficient tissue for assay, in determining any changes or alterations in tissue at various positions in the sample (e.g. equidistant locations in various directions from the sampling path), and in noting changes in tissue as it extends from a center of the sampling area or path. Inaccuracies in the physician's or other operator's anticipation as to exactly how far the device's distal end will advance during sampling can result in the target tissue being overshot or undershot. If the operator does not know with significant accuracy the depth of the tissue of interest, or does not assess where the tissue of interest is with respect to the cutting area of the device, the insertion of the device may result in the cutting area being partially or completely outside of the tissue of interest, resulting in acquisition of tissue that does not provide the information the physician is seeking. Additionally, there may be difficulties in providing speed and/or power of forward thrust for the cannula necessary to move through and shear tens of millimeters of tissue cleanly, regardless of the tissue's density. Forward-thrusting biopsy devices, if not placed properly, if they have less-sharp edges, or if they are under-powered in propelling the cannula forward, can press tissue forward rather than shearing through it. Common results in such cases are less or no sample within the device, or crushing some or all of the tissue. It has been found that the physical state of the sample can affect its usefulness for assay or its ability to provide significant information relative to the health or other characteristics of the sample.