CT Guided Procedures And

Interesting Cases

Stephen Kim, MD

Diagnostic and Interventional Radiology

CT guided procedure benefits

Precise lesion targeting

Clear image guidance for needle placement

Immediate post procedure diagnostic information

Post procedure bleeding

Pneumothorax

CT guided procedure risks

Radiation exposure

Strive for low dose radiation

Typically non contrasted imaging

Sedation and anesthesia

Types of CT guided procedures

Drainage catheter placement Chest

Abdomen / Pelvis

Biopsy Lung

Solid Organ

Lymph nodes

Bone

Tumor ablation

Vertebroplasty

Embolization

Procedure Preparation Team members

Radiologist and other doctors

Procedure technician

Sedation team

Pathology team

CT technician

Clean and organized CT room

No known emergent CT cases

Time out Type of procedure

Laterality

Patient identifiers

Allergies

Tips Prior to patient transport, ask the performing MD about

laterality, patient positioning, and lesion location Supine, prone, decubitus

Have 2 or more additional people help load the patient onto the CT table

Minimize patient movement - secure the torso and extremities with straps

Make space for both the sedation nurse and MD equipment

Disposable versus reusable grid for planning Tape with a string of paperclips work well

Breathing instructions per MD preference

Be aware of the sterile field

Additional Tips

Make sure the room has cleared before each CT scan Make sure everyone is wearing lead if CT fluoro

used

Quickly manage the CT scanner buttons to move the patient in and out between needle advancements

Have appropriate emergency backup ready (ex. anesthesia team, chest tube, code activation)

Procedure Tools

CT Guided Procedures And

Interesting Cases

CT guided Biopsy

CT is commonly utilized for biopsy

Lung, soft tissue, bone Skin entry site identified Needle advanced through tissue into the lesion Lesion sampled Risks: Pneumothorax, bleeding, radiation exposure

Plan and Advance

Planning Scan Guidance Scan

Low Dose CT Lung Biopsy

DLP

Diagnostic Chest CT ~800-1000 mGy*cm

Dreyer Low Dose Chest CT ~400 mGy*cm

Focused CT Lung Bx ~50 mGy*cm

Low Dose CT Concept

IR may use many repeated scans during positioning of biopsy

needles and acquisition of samples – but want to use minimal radiation dose

Lung and bone have high intrinsic contrast – contrast-to-noise

(CNR) maintained despite low signal to noise (SNR) ○ Nodule vs Lung

- Take advantage of this

Soft tissue biopsy – needs more dose, less intrinsic contrast

○ Liver, pelvic biopsy

Axial vs. helical

○ use axial for less overscan and less dose

Axial scan (not helical)

2.5 mm (do not need thinner)

For needle placement

SS100=ASIR100% Dose reduction protocol by

Image reconstruction

Uses noiser data.

Standard Algorithm Maintain signal to noise

mA

GE Dose modulation. Auto mA + Smart mA

Scans assuming oval body shape, mA changes from

Shoulder to lung to mediastinum to lung base

Auto mA and Smart mA on

Very high noise index (lung = high intrinsic contrast [soft tissue / air] or bone)

10 is mimimun mA allowed

50% dose reduction

Manual mA is low in case of problem like invalid scout)

Tolerate lots

Of noise bc

ASIR and IC

Very low estimated dose

80 images is 20 cm range at 2.5 mm thick

Low Dose CT Lung Biopsy Scan 2 Scan 1 Scan 3

Scan 5 Scan 4

CT Biopsy and Ablation of solid

organ masses

Image-guided Spine Procedures

For Relief of Pain

Severe Back Pain Facet Joint

Selective Nerve Root Block

Radiofrequency ablation of a painful bone tumor

Spine compression fracture and Vertebroplasty

Biopsy Vertebroplasty

Bone tumor ablation Facet Injection

Sacral Insufficiency Fractures

Aortic Aneursym Graft and

Endoleak Repair

CT Guided Endoleak Embolization

Post Liquid Embolic

Take Home Points 1. Prior to the patient's arrival, confirm with the

performing physician laterality, patient positioning, lesion location

2. Minimize patient movement - secure the torso and extremities with straps

3. Make sure the room is clear when CT scanning

4. Be aware of the sterile surgical field

5. Have appropriate emergency backup (ex. anesthesia, chest tube, code activation)

Utilize your institutions low dose technique

Small lesions may need increased mA to see better

Start with larger cuts 5mm -> may need thinner 2.5mm

Gantry tilt may be needed to align with the needle trajectory

CT Fluoro Overall more radiation. Use lead protection

Thank You