chapter 18 - ultrasound guided interventional techniques

1970s

Ultrasound is used to assist in interventional procedures since —

masses

not all — can be visualized 

isoechoic

mass may be — to normal tissue

indirect signs of the presence of a mass

displaced vessels, capsule buldges, tumor vessels

bowel gas

abdominal masses may also be obscured by —

computed tomography

under ultrasound and finishing it under —

indications of a biopsy

to confirm malignancy in a mass and determine whether the mass is a primary tumor or metastatic

biopsy

to differentiate a recurrent tumor from scarring is an example of why we do a —

contractions of ultrasound-guided procedures

uncorrectable bleeding disorder, lack of safe needle path, or uncooperative patient

franseen needle

it is used in soft tissue biopsy where a core sample is required, such as in liver or kidney biopsies. The multiple cutting edges ensure a clean and precise core is harvested

chiba needle

commonly used for cytological sampling, drainage, or accessing specific areas under imaging guidance. it is frequently used for lung biopsies or targeting small, deep lesions

spinal needle

primarily designed for spinal or epidural procedures but is also repurposed for biopsies when deeper access is required. In biopsies, it can serve as a guide or be used for aspiration and sampling

core biopsy

uses an automated, spring-loaded device called a biopsy gun to obtain a core of tissue for histologic analysis

10-23 mm

the biopsy device is cocked, and the needle tip is placed just inside the mass, on the outside edge of the mass, or inside the organ itself. The button is then pushed, and the cutting needle is thrown, obtaining a core of tissue, which is deposited into a slot on the inner needle. Various throw lengths are available, ranging from —, which will also correspond to the length of the specimen that is obtained.

ascites

routinely utilized to guide needle placement to drain or to obtain samples from — or pleural effusions

22 or 20

if a small amount of fluid is needed, a — gauge needle may be used

18 or 16

if the fluid is viscous, an — gauge may be used

centesis catheter

if the goal is to drain as much fluid as possible, a special needle called a — is used

2 methods for performing ultrasound-guided procedures

free hand technique, and the use of needle guides

free hand techniques

• performed without the use of a needle guide

• transducer placed in a sterile cover

• A radiologist will hold the transducer in one hand and the needle in the other

• care taken to align the needle with the transducer and the sound beam

• technique allows more flexibility in choosing the needle path

• more technically challenging, especially on deep lesions

pleural fluid

the free hand techniques is typically used to drain ascites, —, and superficial lesions

prefer

some physicians — using free hand techniques for thyroid biopsies, native renal biopsies, and renal transplant biopsies

needle guide technique

• involves using a needle guide

• attached to the transducer

• predicted needle path displayed on screen as a single line or as 2 parallel lines

• mass lined up along the beam

• some transducers offer a choice of angles

• This gives some flexibility around vessels or other structures

benefits of using needle guide

• faster learning curve

• faster placement of the needle

• ability to keep the needle going through an anesthetized area when multiple passes are required

biopsy complications

usually minor and include postprocedural pain or discomfort, vasovagal reactions, and hematomas

serious biopsy complications

• bleeding

• hemorrhage

• pneumothorax

• pancreatitis

• biliary leakage

• peritonitis

• infection

• possibly death

vasovagal reaction

observe patient for indications of —, pain, bleeding from biopsy site

pain

a vasovagal reaction is the nervous system response to a trigger like —

The sonographer’s role in interventional procedures

• locate pathology

• determine various approaches

• offer a recommendation for the best and safest needle path

• Use scanning skills to optimize the image

• Use Doppler to ensure no vessels are in the needle path

• Place the patient in a variety of positions

tricks to seeing the needle tip

• moving the needle up and down in a bobbing motion

• bobbing or jiggling the stylet inside the needle

• scanning and angling the transducer in a superior and inferior motion. This is helpful when the needle is bent out of the plane of the sound beam

• using harmonics or compounding imaging

• A last resort is to remove the needle and start again, closely watching the displacement of the tissue as the needle advances