Computed Tomography Guidance For Bone Biopsy

Eira Roth, M.D.
University of Washington
Department of Radiology
Musculoskeletal Section

Materials

Quantity	Item
1	Radio-opaque grid or marker to place on the patient’s skin for localization purposes.
1	Ink pen to mark the skin
2	Clorhexadine wipes
6–8	Sterile towels
1	Scalpel
1	25 Gauge 1 ½ inch needle
1	18 Gauge 1 ½ inch needle
1	10cc Syringe
10 cc	1%–2% Lidocaine
1	Coaxial bone biopsy device: the selection will be based on the depth of the lesion.
1	Tegaderm bandage

Steps

1. Place the patient in the scanner in the desired position.
2. Apply the adhesive radio-opaque localization grid to the skin overlying the area of the lesion. Ensure that the grid is oriented so that the grid lines will be aligned with the CT gantry. This is to ensure that each line appears as a visible dot on the skin surface on the CT images.
3. Scan the area covered by the grid and choose your biopsy trajectory from the skin surface by using the visible grid markers.
4. Mark the patient’s skin using the grid for guidance. For example, if the lesion appeared directly below the 4th grid marker on CT scan image I36, set the scanner table back to position I36. Most CT scanners have laser localization lights that can be activated once the table is in the desired position. These indicate the location of where that specific image you selected was originally acquired. Along the plane of the red guide light, mark the skin at the location of the 4rth grid line, and remove the adhesive grid.
5. Clean the skin thoroughly and cover the surrounding area with the sterile towels. Leave at least 2 towels available incase you may need them to help stabilize the biopsy device.
6. Using the 18 Gauge needle, fill the 10cc syringe with Lidocaine.
7. Exchange the 18 Gauge needle with a 25 Gauge needle.
8. Using the 25 Gauge needle, anesthetize the skin and soft tissues. There are many ways to do this. However, be sure to begin by creating a large skin wheal at the marked point. Through this advance the needle numbing the soft tissues to the bone and deposit a layer of Lidocaine at the periostium. Leave the needle in place. (If you cannot reach the bone using the standard 25 Gauge 1 ½ needle, exchange it for a 22 Gauge spinal needle of the needed length after performing the skin wheal.)
9. Rescan the patient with the Lidocaine needle in place to confirm location and trajectory.
10. Reposition the needle if needed based on the CT images.
11. Once the skin is numb, and the trajectory has been confirmed, use the scalpel to make a skin nick. Make sure that you use the full diameter of the blade and not only the tip. You must create a cut large enough for your biopsy introducer to pass through.
12. Advance the Introducer Cannula and Stylet through the skin incision and soft tissues to the bone surface.
13. Scan to confirm position.
14. Advance the Cannula until it is firmly anchored in bone close to the lesion. Intermittently scan to confirm position as needed. (Some biopsy devices have depth markers inscribed directly on the Cannula. Other systems have external measuring devices that can affix to the device.)
15. Once the Cannula is anchored, in cortical bone exchange the inner Stylet for the bone biopsy device and advance this into the lesion. Use CT imaging to confirm depth if needed. (Some people leave the Stylet in the biopsy device while advancing, others remove it from the very beginning. This difference is due to a combination of equipment type and personal preference.)
16. Take a biopsy and place the tissue in a sterile container or upon a slide depending on your institutional preference. Repeat biopsy as needed. (Check the specifications of the device you are using. Some require that the biopsy device be advanced by turning in one direction and removed by turning the device in the opposite direction.)
17. Between biopsy passes replace the introducer drill Stylet to decrease the chance of bleeding.
18. Perform a post-biopsy CT scan through the area to ensure that no complications have occurred.