English to Spanish Medical Medical: Health Care

I would greatly appreciate any help with this term!

In context:

If you have not already had a core needle or ultrasound-guided biopsy of your breast tumor, you will have this type of biopsy performed to check the status of the disease. Your doctor will decide what type of biopsy should be performed. To perform an ultrasound-guided biopsy, a tissue sample is withdrawn from the breast tumor using a very thin needle and a syringe, or a special tool to remove a *core of tissue* from the tumor. The needle is guided while being viewed by the doctor using an ultrasound scanner. If you have had a core needle or ultrasound-guided biopsy performed previously, any tissue remaining from that biopsy will be used to check the status of the disease.