Diagnostic ultrasound ( PDFDrive )

CHAPTER 17 Ultrasound-Guided Biopsy of Chest, Abdomen, and Pelvis 601
A
B
C
FIG. 17.1 Ultrasound-Guided Biopsy With and
Without Needle Guide. (A) Ultrasound image
shows a mass in the right lobe of the liver with
needle guide (calipers and *). (B) The needle is seen
within the preselected angle boundaries, with the
tip in the mass. (C) Freehand biopsy of thickened
omentum.
A B C
FIG. 17.2 Biopsy Needle With Central Stylet. (A) Biopsy needle tip before stylet deployment. (B) Stylet is deployed, with the biopsy trough
(arrows) evident on the exposed stylet. (C) Outer cannula is ired over the stylet, allowing tissue to be obtained in the trough.
is clinical concern about a potential complication. In many medical
centers, initial cytologic results are available within this time. If
the results of the initial cytologic analysis are not conclusive, a
repeat biopsy may be performed while the patient is in the
department. When core biopsy tissue samples are obtained,
frozen-section analysis may be performed for diagnosis if the
touch-prep cytology specimen is inconclusive. In this case,
additional samples may be necessary if permanent ixation or
special staining is required.
Needle Visualization
Continuous real-time visualization of needle tip advancement
is one of ultrasound’s greatest strengths as a biopsy guidance
method. Unfortunately, this is frequently the most technically
diicult aspect of ultrasound-guided biopsy for many radiologists.
Beginners may choose to practice on a homemade ultrasound
biopsy phantom to develop the coordination necessary for
ultrasound-guided procedures. 41,42
he most common reason for nonvisualization of the needle
tip is improper alignment of the needle tip and transducer. To
visualize the entire needle, the needle and central ultrasound
beam of the transducer must be in the same plane. his allows
the entire shat of the needle to be visualized. Although malalignment
rarely occurs with the use of a mechanical needle guide,
such parallel placement can be challenging using the freehand
technique, particularly when the radiologist is focused on the
ultrasound image. In many cases the radiologist can simply look
at the alignment of the needle with the transducer to allow gross
correction of path deviation (Fig. 17.3), and then ine-tune the
needle alignment with ultrasound imaging.