AJR 2000; 174:477-485
© American Roentgen Ray Society
Addition of Gadolinium Chelates to Heavily T2-Weighted MR Imaging
Limited Role in Differentiating Hepatic Hemangiomas from Metastases
Genevieve L. Bennett1,2,
Andrea Petersein3,
William W. Mayo-Smith1,
Peter F. Hahn3,
Wolfgang Schima3 and
Sanjay Saini3
1
Department of Diagnostic Imaging, Brown University School of Medicine, Rhode
Island Hospital, 593 Eddy St., Providence, RI 02903.
2
Present address: Department of Abdominal Imaging, New York University Medical
Center, 560 First Ave., New York, NY 10016.
3
Department of Radiology at the Massachusetts General Hospital and Harvard
Medical School, 55 Fruit St., Boston, MA 02114.
Received May 3, 1999;
accepted after revision July 13, 1999.
Address correspondence to G. L. Bennett.
Presented at the annual meeting of the Radiological Society of North
America, Chicago, December 1995.
Abstract
OBJECTIVE. The purpose of this study was to determine whether the
addition of gadolinium-enhanced imaging to heavily T2-weighted MR imaging of
the liver is valuable in differentiating hemangiomas from metastases. The T2
relaxation time was also included in our analysis.
SUBJECTS AND METHODS. Fifty-one patients with 52 proven liver
lesions (24 hemangiomas and 28 metastases) larger than 1 cm underwent MR
imaging at 1.5 T with T2-weighted spin-echo (TR/TE, 3000/80, 160) and
gadolinium chelate-enhanced dynamic T1-weighted gradient-recalled echo
(80/2.6, 80) pulse sequences. Images were reviewed by observers who were
unaware of the patients' clinical history; first, only T2-weighted images were
reviewed and then T2-weighted plus dynamic images were reviewed together. The
T2 relaxation times were calculated for each lesion. Diagnostic accuracy by
each method was compared using receiver operating characteristic analysis.
RESULTS. Mean T2 relaxation times were 76 ± 26 msec for
metastases and 133 ± 25 msec for hemangiomas. The addition of dynamic
scanning to the T2-weighted sequence made a statistically significant
difference for only one observer (p = 0.03). However, it did not make
a statistically significant contribution for either observer when compared
with the T2 relaxation time. Although addition of the dynamic images resulted
in correct diagnosis of six lesions, three lesions were misdiagnosed after
having been correctly characterized on the T2-weighted images alone.
CONCLUSION. When optimized T2-weighted images are obtained and the
T2 relaxation time is calculated, routine use of gadolinium enhancement for
differentiation of hemangiomas from metastases is unnecessary although dynamic
scanning is valuable in selected cases.
Introduction
Liver hemangioma is the most common benign hepatic tumor with a reported
incidence of up to 20% [1] and
is a frequent incidental finding in patients undergoing abdominal imaging for
evaluation of metastatic disease. Differentiation between hepatic hemangiomas
and metastases is a common clinical problem and can have a significant impact
on patient treatment.
MR imaging is frequently used for characterization of liver lesions and
T2-weighted MR imaging has been shown to play a key role in enabling
clinicians to differentiate between hemangiomas and metastases
[2,
3,
4,
5,
6,
7,
8,
9,
10,
11,
12,
13,
14,
15,
16]. However, because
enhancement patterns of benign and malignant liver lesions using extracellular
gadolinium chelates also contribute toward lesion characterization
[17,
18,
19,
20,
21,
22,
23,
24,
25], their routine use in
liver imaging has been advocated.
More recently, heavily T2-weighted imaging
[14,
15,
16,
26] has been shown to be
highly effective for characterization of liver lesions. When performed at a TE
of 80 msec and 160 msec, hemangiomas show increased signal intensity relative
to metastatic lesions. In addition, the calculated T2 relaxation time has been
shown to have high sensitivity and specificity for allowing hemangiomas to be
distinguished from metastases using these parameters
[14,
16]. Therefore, the routine
use of gadolinium chelates may not be necessary for differentiation of
hemangiomas from metastases when optimized T2-weighted imaging is performed.
Elimination of routine use can reduce unnecessary expenditure of imaging time
and cost.
The purpose of this study was to compare the accuracy of differentiation
between hemangiomas and metastases using combined heavily T2-weighted images
in addition to gadolinium chelate-enhanced T1-weighted images versus heavily
T2-weighted images alone and the calculated T2 relaxation time. Furthermore,
our goal was to identify those specific instances in which gadolinium
enhancement is of added value, allowing more selective use of gadolinium in
the characterization of indeterminate lesions.
Subjects and Methods
Patients
Our study population consisted of 51 consecutive patients who underwent MR
imaging of the liver for evaluation of a known or suspected focal liver
lesion. Studies were performed from February 1992 through February 1995,
during which time gadolinium was administered on a routine basis for liver
lesion characterization in our department. The study cohort included 25 women
and 26 men who ranged in age from 33 to 79 years (mean, 55 years). Only one
representative lesion was evaluated in 50 patients, who were selected by a
study coordinator. If more than one lesion was present, the largest lesion was
chosen, with the exception of one patient, in whom two separate lesions were
included in the study. In most instances, cases were filmed so that only the
lesion to be analyzed was presented to the observer.
There were 52 lesions evaluated in this study, 24 hemangiomas and 28
metastatic lesions. In patients with liver metastases, the primary tumor
consisted of the following: colorectal adenocarcinoma (n = 14),
pancreatic islet cell tumor (n = 4), ovarian carcinoma (n =
2), breast carcinoma (n = 2), melanoma (n = 1), esophageal
carcinoma (n = 1), medullary thyroid carcinoma (n = 1), lung
carcinoma (n = 1), Hodgkin's lymphoma (n = 1), and
adenocarcinoma of unknown primary site (n = 1). Because small lesions
are difficult to characterize on most techniques
[4,
21], all lesions included in
the study were 1 cm or larger (mean, 2.5 cm). Fourteen hemangiomas and 15
metastases were 1-2 cm, eight hemangiomas and 11 metastases were between 2 and
5 cm, and two hemangiomas and two metastases were larger than 5 cm. Thus, the
distribution of hemangiomas and metastases with respect to lesion size was
similar.
Verification of Lesion Pathology
In 11 of the 28 patients with metastatic liver lesions, direct hsitologic
proof of diagnosis was available. In the other patients, metastases were
confirmed by imaging criteria consisting of typical imaging features and an
increase in the size or number of lesions on serial cross-sectional images
obtained over a period of at least 6 months. For the 24 hemangiomas,
confirmation of diagnosis was established using criteria established in
previous studies [19,
21,
27,
28]. In 15 patients, follow-up
imaging confirmed stability of the lesion for at least 6 months (range, 6
months-6 years). In six patients, typical imaging features were seen on
another technique (contrast-enhanced CT or sonography) in addition to clinical
follow-up (range, 3-6 years). In three patients, imaging was not performed;
however, at clinical follow-up, all three patients were disease free (range, 6
months-6 years). In the 24 patients with hemangiomas, 10 had a known primary
tumor and 14 did not.
MR Imaging
MR imaging was performed on a 1.5-T unit (Signa; General Electric Medical
Systems, Milwaukee, WI). T2-weighted spin-echo images were obtained with the
following parameters: a TR of 3000 msec, a TE of 80 and 160 msec, a matrix
size of 256 x 128, a field of view of 34-38 cm, and two excitations.
Slice thickness was 8 mm, with a 2-mm gap. Respiratory and flow compensation
were routinely used. For gadolinium chelate-enhanced dynamic scanning,
T1-weighted images were obtained with a spoiled gradient-echo pulse sequence
with the following parameters: a TR of 78 msec, a TE of 2.6 msec, a matrix
size of 256 x 192, a field of view of 34-38 cm, and one excitation. With
this protocol, eight slices were acquired in 16 sec and the liver was covered
in two breath-holds (at end-expiration) using interleaved slice acquisition.
Slice thickness was 10 mm, with no gap. Dynamic gadolinium chelate-enhanced
imaging was performed after a standard dose of 0.1 mmol/kg of gadopentate
dimeglumine (Magnevist; Berlex Laboratories, Wayne, NJ) was administered as an
IV bolus injection. Immediately after injection of the contrast agent, the
gradient-recalled echo sequence was repeatedly performed so that images were
obtained during arterial (from approximately 20-60 sec), portol venous (from
approximately 70-110 sec), and equilibrium (at approximately 3 min)
phases.
Quantitative Image Analysis
Signal intensity measurements were obtained with the largest possible
circular region of interest (ROI) located within the confines of the lesion.
For heterogeneous lesions, central areas of T2 hyperintensity consistent with
necrosis were excluded so that values would represent the nonnecrotic area of
the lesion, as has been done in previous studies
[14,
16]. T2 relaxation times were
calculated with the use of a simplified T2 index as described by Mirowitz et
al. [7]. The T2 relaxation time
was calculated with the following formula: 
TE/ln · (SESD) = T2,
where TE is the difference between the second and first TEs (160 - 80),
ln is the natural logarithm, and SESD (second echo signal drop) is the ratio
of the lesion intensity on the first echo divided by its intensity on the
second echo.
Qualitative Image Analysis
Images were qualitatively evaluated by two experienced observers who were
unaware of the patients' name and history. To eliminate bias in patients with
multiple lesions, studies were refilmed so that in most instances, the lesion
to be analyzed was presented as a solitary mass. For analysis, only three
images were provided: an image that had been obtained through the center of
the lesion, an image above the lesion, and an image below the lesion. Internal
reference standards, including the liver, spleen, and cerebrospinal fluid,
were shown.
The observers were first shown the pair of 80- and 160-msec T2-weighted
images and their interpretations recorded. Immediately afterward, the
observers were shown the T2-weighted images together with the dynamic series,
which included the T1-weighted unenhanced images, and another interpretation
was made. The protocol was designed to mimic the clinical situation and also
avoid any intraobserver variability in assessment of the T2-weighted images.
For each interpretation, the observers graded the lesions on a 5-point scale
of diagnostic confidence, with 1 point representing a diagnosis of definitely
hemangioma and 5 points signifying a diagnosis of definitely metastasis.
Criteria for diagnosis of hemangioma included those well documented in the
literature as being typical for hemangioma, including uniform isointensity to
cerebrospinal fluid on heavily T2-weighted images, well-defined borders, and
peripheral nodular enhancement on gadolinium-enhanced T1-weighted images
[2,
3,
4,
5,
6,
11,
17,
18,
19,
20,
21,
22,
23,
24,
25]. Metastases had a lower
signal intensity than cerebrospinal fluid; metastases had heterogeneous signal
intensity and enhancement and peripheral washout
[11,
18,
19,
22,
23,
25,
29]. The calculated T2
relaxation time was not available to the observers during review of the
images.
Statistical Analysis
Unenhanced heavily T2-weighted images were compared with combined
T2-weighted and contrast-enhanced images for the differentiation of
hemangiomas and metastases using receiver operating characteristic (ROC)
curves [30] determined from
the confidence scores of each of the two observers. Data from the two
observers were not pooled. Software (CLABROC; Metz C, University of Chicago,
IL) was used to generate the ROC curves and calculate the area under the
curves. This program allows a statistical comparison of the estimated ROC
curves to test for equality of either the areas under the curves, the
sensitivity at a specified false-positive fraction, or the specificities at a
specified false-negative fraction. Two-tailed tests were used, with
differences determined to be statistically significant at a p value
of less than 0.05. ROC analysis was also used to compare diagnostic accuracy
for the calculated T2 relaxation time versus blinded review of the T2-weighted
images plus dynamic scanning with gadolinium enhancement.
Results
Mean T2 relaxation times were 133 ± 25 msec for the hemangiomas and
76 ± 26 msec for metastatic lesions. A scatterplot of T2 relaxation
times for hemangiomas versus metastases shows the distribution of T2
relaxation times (Fig. 1).
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Fig. 1. —Scatterplot of T2 relaxation times for hemangiomas
(diamonds) and metastases (circles) shows that highest T2
relaxation time observed among metastases was 193 msec, which was seen for
cystic metastasis from ovarian carcinoma. Highest observed T2 relaxation time
in other metastatic lesions was 98 msec. Only two hemangiomas had T2 values of
less than 98 msec.
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The highest T2 relaxation time observed among metastases was 193 msec. This
lesion was a cystic metastasis from ovarian cancer with a markedly
hyperintense appearance on T2-weighted images. Excluding this lesion, the
highest observed T2 index for the other malignant lesions was 98 msec. Only
two hemangiomas had a T2 relaxation time of less than 98 msec.
Results of the ROC analyses are shown in
Table 1. Addition of the
gadolinium chelate—enhanced imaging to the T2-weighted sequence made a
statistical difference for observer 1 (p = 0.03), but not for
observer 2 (p = 0.81). However, addition of gadolinium
chelate—enhanced scanning did not make a statistically significant
contribution in comparison with the calculated T2 relaxation time for either
observer (p = 0.30 and p = 0.64).
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TABLE 1 T2 Relaxation Time Versus T2-Weighted Images Alone or Combined with
Dynamic Images for Lesion Characterization: ROC Analysis
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In most instances, the correct diagnosis was made from review of unenhanced
images and was not altered by review of the dynamic gadolinium-enhanced images
(Figs. 2A,
2B,
2C,
2D,
2E,
2F and
3A,
3B,
3C,
3D). The addition of the
gadolinium chelate—enhanced images resulted in a change in diagnosis
from either indeterminate or the incorrect diagnosis to the correct diagnosis
of six lesions, including two patients with hemangiomas (Fig.
4A,
4B,
4C,
4D) and four patients with
metastases (Fig. 5A,
5B,
5C) for observer 1 but none
for observer 2. On the other hand, in three patients, the addition of the
gadolinium chelate—enhanced images led to an incorrect diagnosis after
the correct diagnosis had been established on the T2-weighted images alone.
Observer 1 changed to a false diagnosis of a hemangioma and observer 2 changed
to false diagnosis of one hemangioma and one metastasis (Fig.
6A,
6B,
6C). In no instance was the
diagnosis changed to indeterminate. These data are summarized in
Table 2.
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Fig. 2A. —60-year-old man with hemangioma in whom administration of gadolinium
did not alter diagnosis. T2-weighted MR images obtained with TE of 80 msec
(A) and 160 msec (B) show well-circumscribed lesion within
posterior right hepatic lobe (arrow, A). Signal intensity is
isointense to cerebrospinal fluid, which is consistent with hemangioma.
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Fig. 2B. —60-year-old man with hemangioma in whom administration of gadolinium
did not alter diagnosis. T2-weighted MR images obtained with TE of 80 msec
(A) and 160 msec (B) show well-circumscribed lesion within
posterior right hepatic lobe (arrow, A). Signal intensity is
isointense to cerebrospinal fluid, which is consistent with hemangioma.
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Fig. 2C. —60-year-old man with hemangioma in whom administration of gadolinium
did not alter diagnosis. T1-weighted MR images obtained before (C) and
after (D-F) gadolinium administration reveal nodular peripheral
enhancement with complete fill-in on equilibrium phase image (F), which
is consistent with hemangioma.
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Fig. 2D. —60-year-old man with hemangioma in whom administration of gadolinium
did not alter diagnosis. T1-weighted MR images obtained before (C) and
after (D-F) gadolinium administration reveal nodular peripheral
enhancement with complete fill-in on equilibrium phase image (F), which
is consistent with hemangioma.
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Fig. 2E. —60-year-old man with hemangioma in whom administration of gadolinium
did not alter diagnosis. T1-weighted MR images obtained before (C) and
after (D-F) gadolinium administration reveal nodular peripheral
enhancement with complete fill-in on equilibrium phase image (F), which
is consistent with hemangioma.
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Fig. 2F. —60-year-old man with hemangioma in whom administration of gadolinium
did not alter diagnosis. T1-weighted MR images obtained before (C) and
after (D-F) gadolinium administration reveal nodular peripheral
enhancement with complete fill-in on equilibrium phase image (F), which
is consistent with hemangioma.
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Fig. 3A. —53-year-old man with colonic cancer metastasis in whom
administration of gadolinium did not alter diagnosis. T2-weighted MR images
obtained with TE of 80 msec (A) and 160 msec (B) show large
lesion within posterior right hepatic lobe (arrow, A). Signal
intensity is heterogeneous, giving target appearance. This finding was
interpreted as metastasis.
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Fig. 3B. —53-year-old man with colonic cancer metastasis in whom
administration of gadolinium did not alter diagnosis. T2-weighted MR images
obtained with TE of 80 msec (A) and 160 msec (B) show large
lesion within posterior right hepatic lobe (arrow, A). Signal
intensity is heterogeneous, giving target appearance. This finding was
interpreted as metastasis.
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Fig. 3C. —53-year-old man with colonic cancer metastasis in whom
administration of gadolinium did not alter diagnosis. T1-weighted MR images
obtained during portal venous (C) and equilibrium (D) phases of
gadolinium administration reveal enhancement that is predominantly central,
thus confirming this lesion is not hemangioma.
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Fig. 3D. —53-year-old man with colonic cancer metastasis in whom
administration of gadolinium did not alter diagnosis. T1-weighted MR images
obtained during portal venous (C) and equilibrium (D) phases of
gadolinium administration reveal enhancement that is predominantly central,
thus confirming this lesion is not hemangioma.
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Fig. 4A. —43-year-old woman with hemangioma in whom administration of
gadolinium was helpful in establishing diagnosis of lesion that was initially
interpreted as indeterminate. T2-weighted MR images obtained with TE of 80
msec (A) and 160 msec (B) show large hepatic lesion with
heterogeneous signal intensity (arrow, A) that, overall, is
less than that of cerebrospinal fluid.
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Fig. 4B. —43-year-old woman with hemangioma in whom administration of
gadolinium was helpful in establishing diagnosis of lesion that was initially
interpreted as indeterminate. T2-weighted MR images obtained with TE of 80
msec (A) and 160 msec (B) show large hepatic lesion with
heterogeneous signal intensity (arrow, A) that, overall, is
less than that of cerebrospinal fluid.
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Fig. 4C. —43-year-old woman with hemangioma in whom administration of
gadolinium was helpful in establishing diagnosis of lesion that was initially
interpreted as indeterminate. T1-weighted MR images obtained during portal
venous (C) and equilibrium (D) phases of gadolinium enhancement
show peripheral nodular enhancement pattern with near-complete fill-in, which
is consistent with hemangioma.
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Fig. 4D. —43-year-old woman with hemangioma in whom administration of
gadolinium was helpful in establishing diagnosis of lesion that was initially
interpreted as indeterminate. T1-weighted MR images obtained during portal
venous (C) and equilibrium (D) phases of gadolinium enhancement
show peripheral nodular enhancement pattern with near-complete fill-in, which
is consistent with hemangioma.
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Fig. 5A. —37-year-old woman with ovarian carcinoma metastasis in whom
administration of gadolinium was helpful in establishing diagnosis of cystic
metastasis; lesion was initially interpreted as hemangioma. T2-weighted MR
images obtained with TE of 80 msec (A) and 160 msec (B) show
lesion in posterior right hepatic lobe (arrow, A) that appears
isointense to cerebrospinal fluid. This lesion was interpreted as
hemangioma.
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Fig. 5B. —37-year-old woman with ovarian carcinoma metastasis in whom
administration of gadolinium was helpful in establishing diagnosis of cystic
metastasis; lesion was initially interpreted as hemangioma. T2-weighted MR
images obtained with TE of 80 msec (A) and 160 msec (B) show
lesion in posterior right hepatic lobe (arrow, A) that appears
isointense to cerebrospinal fluid. This lesion was interpreted as
hemangioma.
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Fig. 5C. —37-year-old woman with ovarian carcinoma metastasis in whom
administration of gadolinium was helpful in establishing diagnosis of cystic
metastasis; lesion was initially interpreted as hemangioma. T1-weighted MR
image obtained after administration of gadolinium reveals irregular
enhancement pattern, which is not typical of hemangioma.
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Fig. 6A. —36-year-old woman with hemangioma in whom administration of
gadolinium led to incorrect interpretation after correct diagnosis had been
established from T2-weighted images. T2-weighted MR images obtained with TE of
80 msec (A) and 160 msec (B) show lesion within caudate lobe
(arrow, A) that is isointense to cerebrospinal fluid, which is
consistent with hemangioma.
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Fig. 6B. —36-year-old woman with hemangioma in whom administration of
gadolinium led to incorrect interpretation after correct diagnosis had been
established from T2-weighted images. T2-weighted MR images obtained with TE of
80 msec (A) and 160 msec (B) show lesion within caudate lobe
(arrow, A) that is isointense to cerebrospinal fluid, which is
consistent with hemangioma.
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Fig. 6C. —36-year-old woman with hemangioma in whom administration of
gadolinium led to incorrect interpretation after correct diagnosis had been
established from T2-weighted images. T1-weighted MR image obtained during
portal venous phase of gadolinium administration reveals irregular
enhancement, which is more typical for metastasis.
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Discussion
Other investigators have reported that heavily T2-weighted MR imaging
permits discrimination between hemangiomas and malignant tumors with a high
degree of accuracy [14,
15,
16]. Our results support these
findings. Our mean T2 relaxation times for hemangiomas and metastases were
similar to those reported by these authors, and a threshold of 112 msec, as
suggested by McFarland et al.
[14], resulted in 92%
accuracy, 96% sensitivity, and 87% specificity for lesion discrimination.
More important, our results show that compared with the T2 relaxation time
calculated from heavily T2-weighted images, administration of gadolinium
chelates does not make a statistically significant contribution in enabling
clinicians to differentiate hemangiomas from metastases. These results differ
from those of Whitney et al.
[17], who found that
gadolinium chelate—enhanced T1-weighted imaging increased the accuracy
of lesion characterization. However, these authors used a T2-weighted sequence
with TE values of 20 and 70 msec and did not use as heavily a T2-weighted MR
imaging protocol. Similarly, Hamm et al.
[19] used ROC analysis to show
that dynamic contrast-enhanced MR imaging added information to unenhanced MR
imaging studies, thus improving the distinction between benign and malignant
lesions. Hemangiomas were more accurately diagnosed on combined unenhanced and
contrast-enhanced images than on unenhanced images alone. These authors also
used a moderately T2-weighted sequence with a maximum TE of only 90 msec.
In our study, the use of gadolinium chelate statistically improved lesion
characterization for only one observer when compared with using T2-weighted
imaging alone and for neither observer when compared with the calculated T2
relaxation time. The addition of gadolinium-enhanced images was not useful in
most cases in which the unenhanced images were typical for hemangioma or
metastasis. However, in six cases, review of gadolinium-enhanced images did
improve the diagnostic confidence of both observers. These cases included a
large hemangioma that was heterogeneous on the T2-weighted images and a
hemangioma that was only moderately hyperintense on the T2-weighted sequence.
The signal intensity characteristics of hemangiomas have been shown to be
dependent on the relative composition of vascular spaces and connective tissue
within the lesion and on the presence of thrombosis, calcification,
hemorrhage, or fibrosis [5,
31,
32], all of which will vary
with lesion size. Gadolinium chelate enhancement was also helpful in a patient
with a markedly hyperintense cystic metastasis from ovarian carcinoma. In
addition, a metastatic colon carcinoma that appeared moderately hyperintense
on the T2-weighted images was classified as an indeterminate lesion, but this
lesion was correctly diagnosed after review of gadolinium-enhanced images,
which showed peripheral washout—a feature strongly suggestive of
malignancy [29]. Other
investigators have also reported the added value of gadolinium in examination
of patients with neuroendocrine tumors, such as carcinoid and islet cell
tumors, because of their high T2 signal intensity
[27,
33,
34,
35].
Gadolinium-enhanced images were also misleading in the diagnosis of three
lesions. Contrast-enhanced imaging did not help in diagnosing hemangiomas when
the classic pattern of nodular peripheral enhancement was absent and, in fact,
led to the false diagnosis of metastases in one patient in whom the
enhancement pattern was atypical. Semelka et al.
[20] found that progressive
nodular centripetal enhancement will not be seen in all hemangiomas and that
such enhancement varies with lesion size. Nodular peripheral enhancement was
also observed in a metastatic lesion from breast carcinoma, which led to a
false diagnosis of hemangioma. In the study of Lee et al.
[13], metastases from breast
and colon carcinoma mimicked hemangiomas on T2-weighted MR imaging because of
hypervascularity or necrosis.
A limitation of our study is the relatively small number of lesions
(n = 52) analyzed. It is possible that in a larger cohort of
patients, increased benefits of dynamic scanning could be shown. In addition,
we did not evaluate the impact on interpretation when the clinical history is
available to the observer. Hamm et al.
[19] have shown that the
accuracy rate is improved when images are interpreted with knowledge of
clinical history. Finally, pathologic proof was not available for all lesions
included in our study cohort; however, we believe that adequate imaging and
clinical follow-up was available for each patient, thus allowing our
conclusions to be valid.
In conclusion, our results show that the routine use of gadolinium chelates
in conjunction with heavily T2-weighted MR imaging for distinguishing between
hepatic hemangiomas and metastases may not be necessary and, ultimately, may
not be cost-effective. Addition of contrast-enhanced imaging is helpful when
the signal intensity of the lesion is indeterminate or heterogeneous or in the
case of a known primary tumor with potential for either cystic or necrotic
metastases.
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Abstract
Introduction
