DOI:10.2214/AJR.07.3872
AJR 2008; 191:W78
© American Roentgen Ray Society
Double-Contrast MRI in Patients with Cirrhosis
Boris Guiu,
Romaric Loffroy and
Jean-Pierre Cercueil
University Hospital "Le Bocage" Dijon, France
WEB—This is a Web exclusive article.
The article "Double-Contrast MRI for Accurate Staging of
Hepatocellular Carcinoma in Patients with Cirrhosis" by Hanna et al.
[1] clearly shows the high
accuracy (81–85%) of double-contrast MRI, performed with both
superparamagnetic iron oxide (SPIO) and gadolinium, in predicting tumor stage.
We recently reported a large study of 160 double-contrast MRI examinations
performed in 119 successive patients
[2]. In this cohort, in which
the majority of patients were suffering from alcohol-induced cirrhosis, we
obtained a very high (92%; 95% CI, 85–97%) negative predictive value for
double-contrast MRI and excellent interreader agreement (
= 0.98). A
normal double-contrast MRI result was then associated with a very small
likelihood of hepatocellular carcinoma (HCC).
These interesting results are explained by the complementary biologic
information obtained with the double-contrast MRI examination. After
injection, SPIO particles are taken up by Kupffer cells, which are found in
large numbers within regenerative nodules, but are diminished or dysfunctional
in fibrotic tissue and rarely present in HCC. As a result, regenerative
nodules generate a low-intensity signal on T2-weighted images and an even
lower signal on T2*-sensitive sequences, contrary to what happens
with fibrosis or HCC nodules. The addition of gadolinium chelates provides
information on nodule vascularization, which is particularly useful at the
arterial phase when most HCCs are hypervascular.
Hanna et al. [1] observed
that "intense fibrosis can cause false-negative lesion reports by
obscuring nodules" and speculated that "increasing the spatial
resolution of SPIO-enhanced images will lead to better delineation of the
reticulated pattern of fibrosis and improve the visibility of nodules
surrounded by dense fibrosis." We previously reported
[2] that a T1-weighted 2D
spoiled gradient-echo sequence (FLASH 2D) performed 10 minutes after injection
of gadolinium with expansion of the matrix provides a detailed evaluation of
the liver architecture and then makes it possible to distinguish a nodule of
HCC within an area of confluent fibrosis. In fact, lesion-to-fibrosis contrast
is excellent at this phase, first, because HCC disrupts the fibrous structure
of the liver, and second, because fibrosis is progressively enhanced after
injection of gadolinium whereas HCC undergoes a washout. This high-resolution
T1-weighted sequence that we performed at the end of all double-contrast MRI
examinations was obtained by three separate acquisitions to cover the entire
liver with no interslice gaps. This final sequence could also reduce the risk
of misinterpreting vessels as nodules as reported by Hanna et al.
[1].
Although 3D gradient-echo sequences provided by recent scanners should
replace 2D sequences because of their better signal-to-noise ratio, most of
them have an extremely short TE, which would then drastically reduce the T2
and T2* effects of SPIO. To preserve high lesion-to-liver contrast,
the previously mentioned T1-weighted high-resolution sequence is a 2D sequence
with a relatively long TE (4.9 milliseconds), even with our 3T-MRI system.
As stated by Hanna et al.
[1] and Kim et al.
[3], SPIO also causes modest T1
shortening, sometimes responsible for hyperintensity on SPIO-enhanced
T1-weighted images, which can then obscure the enhancement characteristics at
subsequent gadolinium-enhanced dynamic MRI. We recommend performing dynamic
imaging with a 3D gradient-echo sequence with short or ultrashort TE to
improve the detection of gadolinium enhancement by decreasing the initially
observed hyperintensity.
Finally, like Hanna et al.
[1], we no longer use
unenhanced images before the administration of SPIO because such images
provide little diagnostic benefit. The acquisition time is thus as short as a
standard gadolinium-enhanced MRI examination of the liver. This technique
should now be evaluated in a large clinical trial given the promising results
of several studies, including the one by Hanna et al. and ours.
References
- Hanna RF, Kased N, Kwan SW, et al. Double-contrast MRI for accurate
staging of hepatocellular carcinoma in patients with cirrhosis.
AJR 2008; 190:47
-57[Abstract/Free Full Text]
- Guiu B, Loffroy R, Ben Salem D, et al. Combined SPIO-gadolinium
magnetic resonance imaging in cirrhotic patients: negative predictive value
and role in screening for hepatocellular carcinoma. Abdom
Imaging 2007; Oct 3 [Epub ahead of
print]
- Kim MJ, Kim JH, Chung JJ, Park MS, Lim JS, Oh YT. Focal hepatic
lesions: detection and characterization with combination gadolinium- and
superparamagnetic iron oxide–enhanced MR imaging.
Radiology 2003;228
: 719-726[Abstract/Free Full Text]
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