Diagnostic ultrasound ( PDFDrive )

CHAPTER 4 The Liver 133
A
B
C
D
FIG. 4.67 Secondary Signs of Functional Shunt. All images show gross ascites, which suggests a dysfunctional shunt. (A) Gray-scale and
(B) color Doppler images show a patent transjugular intrahepatic portosystemic shunt. Velocities throughout the shunt were about 130 cm/sec,
which is normal. (C) Sagittal image shows that low in the main portal vein is appropriately directed toward the shunt, appearing red. (D) Transverse
image of the porta hepatis shows the ascending left portal venous branch is blue, lowing toward the shunt; this is also the correct direction.
Therefore despite the ascites, the ultrasound evaluation does not show a dysfunctional shunt.
Relative contraindications to percutaneous biopsy are an
uncorrectable bleeding diathesis, an unsafe access route, and
an uncooperative patient. Ultrasound guidance allows real-time
observation of the needle tip as it is advanced into the lesion.
Several biopsy attachments allow continuous observation of the
needle as it follows a predetermined path. Alternatively, many
experienced radiologists prefer a “freehand” technique. Even
small masses (2.5 cm) can undergo successful biopsy using
sonographic guidance. 237 Ultrasound guidance may also be used
in percutaneous aspiration and drainage of complicated luid
collections in the liver. Ultrasound-guided percutaneous ethanol
injection has been used in the treatment of HCC and hepatic
metastases. 238
INTRAOPERATIVE ULTRASOUND
Intraoperative ultrasound is now an established application of
ultrasound technology. he exposed liver is scanned with a sterile,
7.5-MHz transducer or one covered by a sterile sheath. Intraoperative
ultrasound has been found to change the operative strategy
in 31% to 49% of patients undergoing hepatic resection, either
by allowing more precise resection or by indicating inoperability
because of unsuspected masses or venous invasion. 239,240 Studies
emphasize further improvement of surgical outcome with the
addition of CEUS to intraoperative procedures. 241 Improved
detection of metastases on CEUS undoubtedly accounts for this
improvement.