Pancreatic Sonography – Tumors – Updated
Author:
Philip W. Ralls M.D.
Objectives: Upon completion of this CME article, the reader will be able to
1.
Discuss the treatment and clinical outcome for pancreatic malignancies.
2.
Compare and contrast chronic pancreatitis and pancreatic neoplasms.
3.
Describe the application of color Doppler sonography in evaluating pancreatic
tumors.
Pancreatic Neoplasms
Sonography and Computed Tomography (CT) are the primary tools used to detect
focal pancreatic disease, especially pancreatic carcinoma. CT is generally superior because it
routinely images the entire pancreas. Sonography is also superb when the entire pancreas
can be imaged. Occasionally, sonography may delineate pancreatic masses better than
contrast enhanced CT. Unfortunately, even with optimal equipment and scanning technique
(upright, water filled stomach and duodenum), the entire pancreas can be visualized in only
about 25% to 50 % of patients.
Sonography is the primary imaging method used in screening patients with jaundice.
Ultrasound can usually detect pancreatic carcinoma that obstructs the bile duct and may also
identify a pancreatic mass in a patient scanned for abdominal pain. Sonography is
occasionally useful in characterizing abnormalities noted on CT, determining for example,
whether a lesion is cystic or solid.
Pancreatic Ductal Adenocarcinoma
Pancreatic ductal adenocarcinoma is by far the most common primary pancreatic
neoplasm, comprising approximately 80% of all pancreatic neoplasms and about 90% of
malignant epithelial tumors. Pancreatic carcinoma, whose prevalence has tripled during the
last forty years, is one of the commonest causes of cancer death in the United States.
Pancreatic ductal adenocarcinoma is one of the most lethal malignancies, and the overall
five-year survival is poor at 2 % or less.
Sonographically, pancreatic carcinoma is typically (about 60 % of the time) a
hypoechoic mass that deforms the gland's morphology. Homogeneous masses are slightly
more common than heterogeneous masses. In our recent series, about 10% caused no
glandular contour abnormality and were visualized only because tumor echogenicity differed
from the normal pancreas. Occasionally, pancreatic carcinoma is hyperechoic. Masses with
increased echogenicity are common in chronic pancreatitis but rare in carcinoma. Slightly
more than 60% of these carcinomas occur in the pancreatic head; about 5 % are diffuse and
the remaining 35% are found in the body or tail. Calcification occurs in about 5 % of the
masses (figure 1) and is usually focal and scattered, unlike typical chronic pancreatitis
calcifications. Small intralesional cysts occur in about 15 % of patients. Pseudocysts,
related to obstruction of a pancreatic duct, occur in about 5% to 10 % of patients.
Glandular atrophy may occur from obstruction caused by a tumor.
The following findings suggest unresectability: tumor larger than 2 cm, extracapsular
extension, vascular invasion (venous or arterial), lymphadenopathy, or metastatic disease. As
the mortality of the Whipple procedure declines, some surgeons have become more
aggressive. Some surgeons now feel that pancreatic head lesions are unresectable only when
the superior mesenteric artery is involved or when metastatic disease is present. New trials
are needed to see if this more aggressive surgical approach will result in improved survival.
Preliminary thick section contrast enhanced CT often reveals evidence of metastasis or other
signs of unresectability. If no evidence of unresectability is noted, color Doppler
sonography is very useful in assessing vascular invasion and contiguity, which are the usual
keys in determining whether a lesion is resectable or not. High-resolution spiral CT and
color Doppler imaging can both provide this type of information.
Image findings of unresectability are reliable and only rarely can such a tumor be
resected if surgery is attempted. Conversely, many tumors believed resectable because of
their image appearance on CT or sonography cannot be resected for cure at surgery.
Furthermore, the five-year survival of patients undergoing attempted curative resection is
only 5% to 8%, although more recent studies have reported five-year survival in the 10% to
20% range.
Masses Associated with Chronic Pancreatitis
Focal pancreatic enlargement occurs in approximately 30 % of patients with chronic
pancreatitis. Carcinoma and chronic pancreatitis related masses can usually be differentiated
clinically. In addition, the presence of calcification within a mass makes the diagnosis of
pancreatitis almost certain (although a few carcinomas can have calcifications). Hyperechoic
masses, even without discrete calcifications, are usually related to chronic pancreatitis. An
uncalcified iso or hypoechoic mass is nonspecific. In this instance, biopsy or endoscopic
retrograde cholangiopancreatography (ERCP) is indicated to differentiate carcinoma from
chronic pancreatitis. Carcinoma and pancreatitis may both cause obstruction of the
pancreatic duct or extrahepatic bile duct. Obstruction of both ducts, the "double duct sign",
is nonspecific, occurring in both pancreatitis and pancreatic carcinoma. Pseudocysts, while
more frequent in pancreatitis, also occur in both conditions.
Pancreatic Cystic Disease
Cystic pancreatic tumors are relatively uncommon, comprising fewer than 15% of
pancreatic cystic lesions and only a few percent of pancreatic tumors. Cystic pancreatic
neoplasms include serous cystic neoplasms (microcystic adenomas) and mucinous cystic
neoplasms (macrocystic adenomas). Serous cystic neoplasms are almost universally benign,
although a malignant variant has been reported. When image findings typical for microcystic
adenoma are present, asymptomatic or poor risk patients need not undergo surgery. A
serous cystic neoplasm (figure 2) is slightly more common in females and tends to occur in
older individuals.
Morphologically, serous cystic neoplasms contain many tiny cysts (i.e. microcystic),
most of which are smaller than 2 cm. Occasionally, a few larger cysts are present. A
distinctive but inconsistent feature is a central stellate fibrotic scar that frequently calcifies
(seen in about 50% of tumors). Sonographically, microcystic adenomas are echogenic in
regions of the tumor where there are many tiny cysts. Through transmission is frequent.
The central stellate scar with calcification may be identified, suggesting the diagnosis.
Mucinous cystic neoplasms consist of large cysts (i.e. macrocystic), easily imaged
with CT or sonography. Most tumors are located in the tail or body of the pancreas and are
much more common in females, approaching a 10 to 1 predominance. Because
differentiation between benign and malignant mucinous cystic neoplasms is often impossible
even pathologically, all tumors are considered malignant and surgical removal is indicated.
Calcifications occur in approximately 20% of these neoplasms (compared to about one half
of the serous cystic neoplasms).
Sonography can reveal other cystic masses that may be comprised of simple
unilocular cysts or septated cysts of variable size. The septations may be few or many, quite
thin or relatively thick, and polypoid.
Endocrine Tumors of the Pancreas
Endocrine tumors are a small but important group of pancreatic neoplasms that
generally originate from the pancreatic islet cells. Insulinomas and gastrinomas are the most
common endocrine tumors. Other tumors that can originate from the islet cells are
glucagonoma, somatostatinoma, vasoactive intestinal peptide tumors (VIPoma), carcinoid
tumors, pheochromocytoma, and combined histology tumors. These tumors tend to be
small and are malignant, with the exception of the insulinoma. It is difficult to image islet
cell tumors because they are usually small when the patient presents with hormonal
abnormalities. Insulinomas and gastrinomas are frequently less than 2 cm in diameter. Thin
section dynamic incremental contrast enhanced CT or angiography can sometimes reveal
these lesions. Intraoperative sonography is useful in localizing occult neoplasms.
Published success rates for the detection of insulinomas vary from 25% to 60%.
The results for gastrinomas are worse in that approximately only 20% are detected.
Sonographically, islet cell tumors are usually well defined and round or oval in shape. They
generally appear hypoechoic compared to the normal pancreatic parenchyma. On occasion,
the only detectable abnormality may be an alteration of the pancreatic contour. Increased
echogenicity from calcification has been reported. Most islet cell tumors are hyperfunctioning. When they are not hyper-functioning, these pancreatic endocrine tumors may
grow to a large size before being detected.
Metastasis to the Pancreas
In autopsy series, the most common pancreatic neoplasm is metastatic carcinoma.
Primary tumors that commonly metastasize to the pancreas include breast, lung, colon and
stomach cancers, as well as, melanoma. Pancreatic metastases are rarely significant clinically,
because they generally occur late in patients who have widespread metastatic disease.
Resectability of Periampullar Neoplasms / The Role of Color Doppler
The prognosis for pancreatic carcinoma and other pancreatic neoplasms is grim,
although periampullar neoplasms (other than pancreatic ductal adenocarcinoma) have a
somewhat better prognosis. The only hope for cure remains surgical resection. In the last
decade, surgical results have improved and operative morbidity and mortality have
decreased. In recent series, resection for cure has been possible in 15% to 20 % of
unselected patients and 29% to 34% of patients screened as suitable candidates for curative
resection.
Sonography is often the first modality used to image patients with pancreatic
carcinoma, as these patients usually present with jaundice or abdominal pain. Despite this,
little work has been done to assess the usefulness of sonography in evaluating the
resectability of pancreatic neoplasms. In most recent discussions of imaging in pancreatic
neoplasms, transabdominal sonography has been almost totally ignored.
We have developed a technique for assessing the resectability of pancreatic tumors
using color Doppler sonography. In a retrospective analysis of 51 patients referred for color
Doppler sonographic evaluation of the resectability of a pancreatic neoplasm, 45 had an
adequate evaluation with follow-up. Vessels that were touched or occluded by tumor were
categorized according to a Pancreatic Color Doppler Score (Table 1). Other factors
affecting resectability (metastasis or enlarged lymph nodes) were recorded. Findings were
correlated to the surgical and pathologic findings of resectability and unresectability.
TABLE 1 - PANCREATIC COLOR DOPPLER SCORE
PCDS 0 Tumor did not touch a vessel.
PCDS 1
Tumor touched, 1% - 24% around the vessel circumference.
PCDS 2 Tumor touched, 25% - 49% around the vessel
circumference.
PCDS 3 Tumor touched, 50% - 99% around the vessel
circumference.
PCDS 4 Tumor touched, 100% around the vessel circumference.
“Encasement”
PCDS 5 Occluded vessel.
All 18 patients with circumferential tumor or vascular occlusion (PCDS 4 & 5) could
not be resected (figure 3). All of the margins were negative in the 10 patients where the
tumor did not touch a vessel (PCDS 0). All 30 patients considered unresectable
sonographically were also unresectable for cure based on surgical and pathological
information. Six of 15 (40%) that were considered resectable sonographically were
unresectable for cure. Color Doppler sonography influenced therapy in 10 of 45 patients
(22% overall).
Doppler sonography has been found useful in assessing the resectability of other
tumors such as cholangiocarcinoma. Our data comprise a feasibility study that suggests
color Doppler sonography can greatly enhance the usefulness of sonography in evaluating
pancreatic neoplasms.
In the important area of determining that a patient cannot be cured by surgical
resection, our data showed a positive predictive value of 100%. That is, color Doppler
sonography unresectability correlated with all 30 patients who were unresectable for cure. In
those cases, no further evaluation would be required.
The prediction of unresectability of pancreatic carcinoma with CT scanning is also
very reliable; however, our data suggest that color Doppler sonography likewise may be
reliable. Identifying patients who are potentially resectable with a high probability for cure is
more difficult. One potential problem in using color Doppler sonography to assess
resectability of pancreatic tumors is that the examiner must have significant experience in
abdominal color Doppler imaging. We have learned, nevertheless, that color Doppler
evaluation of patients with pancreatic masses is actually simpler than evaluation of patients
with a normal pancreas. Pancreatic neoplasms tend to be non-compressible and are often
immobile. Thus, compression with a large footprint curved linear array transducer allows
visualization of the mass and its relationship to any vessels. In this study we visualized 643
of 647 possible vessels (99.4 % visualization rate) and achieved complete technical success in
49 of 51 patients (96%). It should also be remembered that the great majority of pancreatic
neoplasms occur in the head and body of the pancreas, which are the easiest regions to
visualize sonographically.
Can color Doppler sonography decrease the need for CT in assessing resectability of
pancreatic neoplasms? The role of color Doppler sonography in the evaluation of pancreatic
tumors awaits the results of prospective trials. Our data, however, suggest that color
Doppler sonography is promising. It was reliable in detecting unresectable lesions in our
series, detecting all 30 patients who were unresectable for cure. A “touch/no touch” color
Doppler analysis that compared color Doppler findings to tumor free margins showed that
when tumor did not touch vessels, the margins were negative (10 of 10 patients). Color
Doppler sonography, a comfortable, non-invasive, and relatively inexpensive examination,
may be an effective screening tool for evaluating resectability. If color Doppler sonography
can correctly predict unresectability, then 80% of pancreatic carcinoma patients would
require no further expensive or invasive imaging evaluation, and palliative management
could proceed. Thus, only 20% of patients would require further evaluation (such as CT,
ERCP, laparoscopy, etc.).
Sonography has been almost totally ignored in the most recent discussions regarding
imaging in pancreatic and periampullar neoplasms. It seems clear from our data that color
Doppler sonography can be very useful in evaluating the resectability of pancreatic
neoplasms. Any future evaluation of imaging and management of pancreatic tumors should
include color Doppler sonography.
Figures
1
Pancreatic Carcinoma with calcification.
2
Microcystic Adenoma (Serous Cystic Neoplasm)
3
Pancreatic Carcinoma encases the superior mesenteric artery – PCDS 4.
References or Suggested Reading:
1.
Sofuni A, Iijima H, Moriyasu F, et al. Differential diagnosis of pancreatic tumors
using ultrasound contrast imaging. J Gastroenterol. 2005;40:518-525.
2.
Scialpi M, Midiri M, Bartilotta TV, et al. Pancreatic carcinoma versus focal
pancreatitis: contrast-enhanced power Doppler ultrasonography findings. Abdom
Imaging. 2005;30:222-227.
3.
Rickes S, Malfertheiner P. Echo-enhanced sonography – an increasingly used
procedure for the differentiation of pancreatic tumors. Dig Dis. 2004;22:32-38.
4.
Alvarez C, Livingston EH, Ashley SW, et al.. Cost-benefit analysis of the work-up
for pancreatic cancer. Am J Surg 1993;165:53-60.
5.
Angeli E, Venturini M, Vanzulli A, et al. Color Doppler imaging in the assessment
of vascular involvement of pancreatic carcinoma. AJR 1997;168:193-197.
6.
Cameron JL, Pitt HA, Yeo CJ, et al. One hundred and forty-five consecutive
pancreaticoduodenectomies without mortality. Ann Surg 1993;217:430-438.
7.
Freeny PC, Traverso LW, Ryan JA. Diagnosis and staging of pancreatic
adenocarcinoma with dynamic computed tomography. Am J Surg 1993;165:600-606.
8.
Fuhrman GM, Charnsangavej C, Abbruzzese JL, et al. Thin-section contrastenhanced computed tomography accurately predicts the resectability of malignant
pancreatic neoplasms. Am J Surg 1994;167:104-113.
9.
Geer RJ, Brennan MF. Prognostic indicators for survival after resection of
pancreatic adenocarcinoma. Am J Surg 1993;165:68-73.
10.
Gudjonsson B. Carcinoma of the pancreas: critical analysis of costs, results of
resections, and the need for standardized reporting. J of Am Col Surgeons
1995;181:483-503.
11.
Hann LE, Fong Y, Shriver CD, et al. Malignant hepatic hilar tumors: Can
ultrasonography be used as an alternative to angiography with CT arterial
portography for determination of resectability? J Ultrasound Med 1996;15:37-45.
12.
Hough DM, Stephens DH, Johnson CD, Binkovitz LA. Pancreatic lesions in von
Hippel-Landau disease: Prevalence, clinical significance, and CT findings. AJR
1994;162:1091-1094.
13.
Ikeda M, Sato T, Morozumi A, Fujino MA, et al. Morphologic changes in the
pancreas detected by screening ultrasonography in a mass survey, with special
reference to main duct dilatation, cyst formation, and calcification. Pancreas
1994;9:508-512.
14.
Klinkenbijil, JHG, Jeekel J, Schmitz PIM, et al. Carcinoma of the pancreas and
periampullary region: palliation versus cure. Br J Surg 1993;80;1575-1578.
15.
Looser C, Stain SC;, Baer HU, Triller J, Blumgart LH. Staging of hilar
cholangiocarcinoma by ultrasound and duplex sonography: a comparison with
angiography and operative findings. Br J Radiol 1992;65:871.
16.
Mathieu D, Guigui B, Valette PJ, et al. Pancreatic cystic neoplasms. Radiol Cl
North Am 1998;27:163-176.
17.
Megibow AJ, Zhou XH, Rotterdam H, et al. Pancreatic adenocarcinoma: CT versus
MR imaging in the evaluation of resectability - Report of the radiology diagnostic
oncology group. Radiology 1995;195:327-332.
18.
Nghiem HV, Freeny PC. Radiologic staging of pancreatic adenocarcinoma. Radiol
Clin North Am 1994;32:71-79.
19.
Nitecki SS, Sarr MG, Colby TV, vanHeerden JA. Long-term survival after resection
for ductal adenocarcinoma of the pancreas. Is it really improving? Ann Surg
1995;221:59-66.
20.
Ralls PW, Wren SM, Radin DR, et al. Color Doppler sonography in evaluating the
resectability of periampullar pancreatic tumors. J Ultrasound Med 1997;16:131-140.
21.
Tomiyama T, Ueno N, Tano S, et al, Assessment of arterial invasion in pancreatic
cancer using color Doppler ultrasonography. Am J Gastroenterol 1996;91:1410-6.
22.
Trede M, Schwall G, Saeger HD. Survival after pancreatoduodenectomy. Ann Surg
1990;211:447-458.
23.
Vellet AD, Romano W, Bach DB, et al. Adenocarcinoma of the pancreatic ducts:
Comparative evaluation with CT and MR imaging at 1.5T. Radiol 1992;183:87-95.
24.
Wade TP, El-Ghazzawy AG, Virgo KS, Johnson FE. The Whipple resection for
cancer in U.S. department of veterans affairs hospitals. Ann Surg 1995;221:241-248.
25.
Wade TP, Radford DM, Virgo KS, Johnson FE. Complications and outcomes in the
treatment of pancreatic adenocarcinoma in the United States veteran. J Am Coll
Surg 1994;179:38-48.
26.
Warshaw AL and Fernandez-del Castillo C. Pancreatic carcinoma. N Engl J Med
1992;326:455-465.
27.
Warshaw AL, Gu Z, Wittenberg J, Waltman AC. Preoperative staging and
assessment of resectability of pancreatic cancer. Arch Surg 1990;125:230-233.
28.
Watanapa P and Williamson RCN. Surgical palliation for pancreatic cancer:
developments during the past two decades. Br J Surg 1992;79:8-20.
29.
Wren SM, Ralls PW, Stain SC, et al. Assessment of resectability of pancreatic head
and periampullary tumors by color Doppler Doppler sonography. Arch Surg
1996;131:812-818.
About the Author
Dr. Philip W. Ralls is a Professor of Radiology at Keck School of Medicine,
University of Southern California. He is an active Radiologist and is a Fellow of the
American College of Radiology and numerous other professional organizations.
Dr. Ralls has presented numerous lectures on ultrasound topics at many different
conferences around the country and is actively involved in research. In addition, he has
authored several publications in peer-review medical journals.
Examination:
1.
When evaluating the pancreas for the presence of tumors, sonography is superb
when the entire pancreas can be imaged. Unfortunately, even with optimal
equipment and scanning technique, the entire pancreas can be visualized in only
about _______ of patients.
A.
5% to 12%
B.
13% to 19%
C.
20%% to 25%
D.
25% to 50%
E.
50% to 65%
2.
All of the following statements are true EXCEPT
A.
Sonography is the primary imaging method used in screening patients with
jaundice.
B.
Sonography is not useful in characterizing abnormalities noted on CT.
C.
Ultrasound may identify a pancreatic mass in a patient scanned for
abdominal pain.
D.
Ultrasound can usually detect pancreatic carcinoma that obstructs the bile
duct.
E.
Sonography is superb when the entire pancreas can be imaged.
3.
Pancreatic ductal adenocarcinoma is by far the most common primary pancreatic
neoplasm, comprising approximately _____ of all pancreatic neoplasms.
A.
80%
B.
70%
C.
60%
D.
50%
E.
40%
4.
Which of the following is a true statement?
A.
Sonographically, pancreatic carcinoma is typically a hyperechoic mass that
does not deform the gland's morphology.
B.
Pancreatic ductal adenocarcinoma is one of the most lethal malignancies, and
the overall five-year survival is poor at 30% or less.
C.
Pancreatic carcinoma, whose prevalence has tripled during the last forty
years, is one of the commonest causes of cancer death in the United States.
D.
Heterogeneous masses are slightly more common than homogeneous
masses.
E.
Masses with increased echogenicity are common in carcinoma but rare in
chronic pancreatitis.
5.
Slightly more than _____ of pancreatic ductal adenocarcinomas occur in the
pancreatic head.
A.
20%
B.
30%
C.
40%
D.
60%
E.
80%
6.
All of the following findings suggest unresectability of pancreatic ductal carcinoma
EXCEPT
A.
tumor less than 2 cm
B.
extracapsular extension
C.
vascular invasion (venous or arterial)
D.
lymphadenopathy
E.
metastatic disease
7.
The five-year survival of patients undergoing attempted curative resection in the
more recent studies have reported a range of
A.
50% to 60%
B.
40% to 50%
C.
30% to 40%
D.
20% to 30%
E.
10% to 20%
8.
Regarding carcinoma and masses associated with chronic pancreatitis, all of the
following statements are true EXCEPT
A.
Focal pancreatic enlargement occurs in approximately 30 % of patients with
chronic pancreatitis.
B.
The presence of calcification within a mass makes the diagnosis of
pancreatitis certain because carcinomas do not have calcifications.
C.
Carcinoma and pancreatitis may both cause obstruction of the pancreatic
duct or extrahepatic bile duct.
D.
Carcinoma and chronic pancreatitis related masses can usually be
differentiated clinically.
E.
Pseudocysts, while more frequent in pancreatitis, can occur in both
conditions.
9.
Cystic pancreatic tumors are relatively uncommon, comprising fewer than ____ of
pancreatic cystic lesions and only a few percent of pancreatic tumors.
A.
45%
B.
35%
C.
25%
D.
15%
E.
5%
10.
Regarding serous cystic neoplasms, all of the following are true EXCEPT
A.
They are almost universally benign.
B.
C.
D.
E.
When image findings typical for these neoplasms are present, asymptomatic
or poor risk patients need not undergo surgery.
Another name for these tumors is macrocystic adenoma.
They are slightly more common in females and tend to occur in older
individuals.
A distinctive but inconsistent feature is a central stellate fibrotic scar that
frequently calcifies (seen in about 50% of tumors).
11.
Regarding mucinous cystic neoplasms, which of the following statements is true?
A.
They consist of very small cysts that are easily imaged with CT but not by
sonography.
B.
Because differentiation between benign and malignant mucinous cystic
neoplasms is often impossible, all tumors are considered malignant and
surgical removal is indicated.
C.
They are much more common in males, approaching a 10 to 1
predominance.
D.
Most tumors are located in the head of the pancreas.
E.
Calcifications occur in approximately 50% of these neoplasms (compared to
about only 20% in the serous cystic neoplasms).
12.
Regarding endocrine tumors, ________ and gastrinomas are the most common.
A.
glucagonomas
B.
carcinoid tumors
C.
somatostatinomas
D.
pheochromocytoma
E.
insulinomas
13.
All of the following are pancreatic tumors that can originate from the islet cell
EXCEPT
A.
pheochromocytoma
B.
melanoma
C.
glucagonoma
D.
vasoactive intestinal peptide tumor
E.
somatostatinoma
14.
Regarding islet cell tumors, all of the following are true statements EXCEPT
A.
Published success rates for the detection of insulinomas vary from 25% to
60%.
B.
Insulinomas and gastrinomas are frequently less than 2 cm in diameter.
C.
It is relatively easy to image islet cell tumors because they are usually large
when the patient presents with hormonal abnormalities.
D.
Sonographically, islet cell tumors are usually well defined and round or oval
in shape.
E.
They generally appear hypoechoic compared to the normal pancreatic
parenchyma.
15.
In autopsy series, the most common pancreatic neoplasm is
A.
combined histology tumor
B.
C.
D.
E.
ductal adenocarcinoma
metastatic carcinoma
serous cystic tumor
gastrinoma
16.
Primary tumors that commonly metastasize to the pancreas include all of the
following EXCEPT
A.
melanoma
B.
lung cancer
C.
breast cancer
D.
stomach cancer
E.
basal cell cancer
17.
Sonography is often the first modality used to image patients with pancreatic
carcinoma, as these patients usually present with
A.
jaundice or abdominal pain.
B.
vomiting.
C.
abnormal blood tests.
D.
an abdominal mass.
E.
diarrhea.
18.
Pancreatic neoplasms tend to be
A.
non-compressible and are often immobile.
B.
non-compressible but are often mobile.
C.
non-visible by ultrasound so compression and mobility are of no use.
D.
compressible but are often immobile.
E.
compressible and are often mobile.
19.
In the study discussed in this article, a complete technical success sonographically
was achieved in _____ of 51 patients.
A.
73%
B.
79%
C.
85%
D.
89%
E.
96%
20.
In the study discussed in the article, a “touch/no touch” color Doppler analysis that
compared color Doppler findings to tumor free margins showed that when tumor
did not touch vessels, the margins were negative in
A.
30 of 30 patients
B.
20 of 20 patients
C.
15 of 15 patients
D.
10 of 10 patients
E.
5 of 5 patients