Diagnostic ultrasound ( PDFDrive )

242 PART II Abdominal and Pelvic Sonography
PANC CA
Encased
celiac
1
A
A
B
FIG. 7.72 Pancreatic Ductal Adenocarcinoma Encasing Celiac Axis and Aorta. (A) Transverse color Doppler sonogram shows a hypoechoic
mass (arrows) that encases the aorta (A) and celiac axis. (B) Computed tomography image at a similar level shows the same indings. This lesion
is clearly unresectable for cure.
Stenotic SMA
SMA
Mass
Mass
A
B
FIG. 7.73 Pancreatic Ductal Adenocarcinoma Encasing Superior Mesenteric Artery (SMA). (A) Longitudinal color Doppler sonogram shows
that hypoechoic mass, which also encases the celiac axis, narrows the SMA (arrow). (B) Transverse color Doppler sonogram in a different patient
demonstrates much more subtle encasement (arrowheads). Ductal adenocarcinoma narrows and occludes veins much more frequently than arteries.
This narrowing is equivalent to classic angiographic encasement. See also Video 7.8.
CYSTIC PANCREATIC LESIONS
Understanding cystic pancreatic lesions is increasingly important
because improved imaging techniques result in the detection of
progressively more of these lesions, oten as incidental indings.
72,148,149 New concepts and pathologic deinitions of cystic
neoplasms, especially mucinous and intraductal papillary forms,
have altered the approach to diagnosis and management of these
lesions.
Although the number of cystic lesions of the pancreas detected
is increasing because of improved imaging techniques, 148,149
pancreatic pseudocyst remains the most common, accounting
for 75% or more of all cystic lesions. 72 A careful history must
be obtained to rule out previous acute or chronic pancreatitis,
so as to minimize the chance of confusing a pseudocyst with
other cystic masses. Nonpseudocyst lesions include simple cysts
and cystic neoplasms. Although certain image features may be
helpful, the diferential diagnosis of cystic lesions, especially when
small, is unreliable by CT or MRI. Visser et al. 77 found that, even
when their diagnostic certainty was 90% or greater, characterization
was unreliable.
Fortunately, it appears reasonably safe to follow unilocular
pancreatic cystic lesions with a diameter 3 cm or less 72 (Fig.
7.74). Sahani et al. 150 reported that 35 of 36 unilocular pancreatic
cystic lesions 3 cm or less were benign. Internal septations were
associated with borderline or in situ malignancy in 10 of 50
cases (20%). Other surgeons believe that resection of these lesions
is a better approach. 73,151 he usefulness of tumor markers and
cyst luid cytology is debated. 73,152-154 Most agree that high-risk
patients and features should be managed more aggressively,