DOI:10.2214/AJR.07.3182
AJR 2008; 190:1076-1084
© American Roentgen Ray Society
Body MRI Using IDEAL
Daniel N. Costa1,2,
Ivan Pedrosa1,
Charles McKenzie1,3,
Scott B. Reeder4 and
Neil M. Rofsky1
1 Department of Radiology, Beth Israel Deaconess Medical Center, Boston,
MA.
2 Present address: Departmento de Radiologia, Hospital Sirio-Libanês, Rua
Dona Adma Jafet, 91, São Paulo – SP, Brazil 01308-050.
3 Present address: Department of Medical Biophysics, Schulich School of Medicine
& Dentistry, University of Western Ontario, London, ON, Canada.
4 Department of Radiology, University of Wisconsin, Madison, WI.
Received September 18, 2007;
accepted after revision October 29, 2007.
N. M. Rofsky provides research support for GE Healthcare.
Address correspondence to D. N. Costa
(dnobrega{at}gmail.com).
CME
This article is available for CME credit. See
www.arrs.org
for more information.
Abstract
OBJECTIVE. The intrinsic differences of water and fat protons in the
MR environment allow selective interrogation of their contribution to the MR
signal. Fat-suppression techniques and chemical shift imaging are routinely
used in clinical body MRI. Iterative decomposition of water and fat with echo
asymmetry and least-squares estimation (IDEAL) is a novel imaging technique
for separating fat and water.
CONCLUSION. This article describes the basic principles of IDEAL MRI
and illustrates the use of IDEAL imaging as an alternative to fat-suppression
techniques and chemical shift imaging for body MRI.
Keywords: body imaging • chemical shift • fat suppression • iterative decomposition of water and fat with echo asymmetry and
least-squares estimation (IDEAL) • MRI
Introduction
Fat suppression is a generic term referring to a variety of strategies
designed to eliminate the sig nal from lipids. Fat-suppression techniques are
routine in body MRI to accurately characterize adipose tissue, to mini mize
chemical shift misregistration artifacts, and to expand the dynamic range of
the MR images for better depiction of pathology on T2-weighted images and
contrast-enhanced T1-weighted images. To date, the most commonly used MRI
techniques for fat suppression include frequency-selective fat saturation,
inversion recovery, water excitation, or a combination of these techniques
[1].
Limitations of these popular techniques include failed or erroneous signal
suppression when local magnetic field (B0) or radiofrequency (B1)
inhomogeneities are encountered and the nonspecific suppression of a short T1
signal when it approximates that of fat
[2].
The IDEAL Technique
Different MR strategies have been developed over the years to characterize
the independent contributions of water and fat protons to the overall MR
signal. Chemical shift imaging techniques exploit the differences in
precession velocities of fat and water protons to detect small amounts of
intravoxel fat, a hallmark of certain disorders such as hepatic steatosis and
adrenal adenomas. These imaging techniques are derived from the principles
first described by Dixon [3].
They are based on decomposing fat and water proton signals according to their
resonant frequency difference, or chemical shift, to isolate these two
components into two separate images. By adding and subtracting the two complex
images (images with both magnitude and phase information) from in-phase and
opposedphase imaging, selective water and fat images are generated
[3,
4]. Thus, instead of being a
true fat-suppression technique, the Dixon method is a water–fat
separation method.
Further modifications in the Dixon technique—for example, those
implemented by Glover and Schneider
[5] and Reeder et al.
[4,
6]—have been proposed to
overcome problems secondary to magnetic field inhomogeneities. Such
modifications have resulted in the three-point Dixon method and, ultimately,
in the so-called iterative decomposition of water and fat with echo asymmetry
and least-squares estimation, or IDEAL, technique. Instead of collecting just
two images with opposed fat and water phases, both of these techniques acquire
three images, each with a different relative phase between the water and fat
signals. These approaches account for both B0 and B1 magnetic field
inhomogeneities, thereby facilitating the fat–water separation
process.
In the IDEAL technique, the echo times of the three images are carefully
chosen so that the reconstructed fat-only and water-only images have the
maximum possible signal-to-noise ratio (SNR)
[7]. IDEAL is compatible with
essentially any pulse sequence, and it has been combined with a wide variety
of clinically relevant sequences, including fast spin echo
[4] (Figs.
1A,
1B, and
1C), steady-state free
precession (SSFP) [8], and
T1-weighted spoiled gradient-recalled echo (GRE)
[6]. This flexibility in
sequence combination provides fat- and water-separated images with any desired
contrast, including T2-weighted, T1-weighted, and proton
density–weighted images, with motion compensation—that is,
respiratory gating (Figs. 2A,
2B,
2C, and
2D)—with either 2D or 3D
acquisitions and with the use of contrast media
[4].
View larger version (103K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —23-year-old woman with inflammatory bowel disease and focal
pancreatitis in pancreatic tail. Axial fast spin-echo T2-weighted iterative
decomposition of water and fat with echo asymmetry and least-squares
estimation (IDEAL) image (TR/TE, 4,000/90) shows clear transition between
normal body of pancreas and edematous pancreatic tail
(arrowheads).
|
|
View larger version (99K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B —23-year-old woman with inflammatory bowel disease and focal
pancreatitis in pancreatic tail. This finding is less conspicuous in
corresponding single-shot fast spinecho (643/58) (B) and fast-recovery
fast spin-echo (2,200/85) (C) T2-weighted images obtained during same
examination.
|
|
View larger version (93K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C —23-year-old woman with inflammatory bowel disease and focal
pancreatitis in pancreatic tail. This finding is less conspicuous in
corresponding single-shot fast spinecho (643/58) (B) and fast-recovery
fast spin-echo (2,200/85) (C) T2-weighted images obtained during same
examination.
|
|
View larger version (116K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A —45-year-old woman with right adrenal myelolipoma. Because
patient was unable to hold her breath, this 3D iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL)
sequence was respiratory-gated Axial gradient-recalled echo T1-weighted IDEAL
water-only (A), fat-only (B), in-phase (C), and
opposed-phase (D) images are derived from single acquisition (TR/TE,
6.8/2). Note area containing bulk fat (arrow, B) in lesion on
fat-only image (B). Opposed-phase image (D) is easily recognized
because of "edge artifact" (arrowheads, D) at
fat–water interfaces.
|
|
View larger version (119K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B —45-year-old woman with right adrenal myelolipoma. Because
patient was unable to hold her breath, this 3D iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL)
sequence was respiratory-gated Axial gradient-recalled echo T1-weighted IDEAL
water-only (A), fat-only (B), in-phase (C), and
opposed-phase (D) images are derived from single acquisition (TR/TE,
6.8/2). Note area containing bulk fat (arrow, B) in lesion on
fat-only image (B). Opposed-phase image (D) is easily recognized
because of "edge artifact" (arrowheads, D) at
fat–water interfaces.
|
|
View larger version (123K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C —45-year-old woman with right adrenal myelolipoma. Because
patient was unable to hold her breath, this 3D iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL)
sequence was respiratory-gated Axial gradient-recalled echo T1-weighted IDEAL
water-only (A), fat-only (B), in-phase (C), and
opposed-phase (D) images are derived from single acquisition (TR/TE,
6.8/2). Note area containing bulk fat (arrow, B) in lesion on
fat-only image (B). Opposed-phase image (D) is easily recognized
because of "edge artifact" (arrowheads, D) at
fat–water interfaces.
|
|
View larger version (128K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2D —45-year-old woman with right adrenal myelolipoma. Because
patient was unable to hold her breath, this 3D iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL)
sequence was respiratory-gated Axial gradient-recalled echo T1-weighted IDEAL
water-only (A), fat-only (B), in-phase (C), and
opposed-phase (D) images are derived from single acquisition (TR/TE,
6.8/2). Note area containing bulk fat (arrow, B) in lesion on
fat-only image (B). Opposed-phase image (D) is easily recognized
because of "edge artifact" (arrowheads, D) at
fat–water interfaces.
|
|
IDEAL imaging provides uniform and reliable fat suppression throughout the
body, including the head and neck
[4], breast
[9] (Figs.
3A and
3B), heart
[8,
9], abdomen
[4,
9], pelvis
[4] (Figs.
4A and
4B), and extremities
[4]. An additional advantage of
IDEAL is that in-phase and opposed-phase images, and fat-only and water-only
images, are obtained during a single acquisition (Figs.
2A,
2B,
2C, and
2D). Thus, a single acquisition
with IDEAL imaging has the potential to simplify body MRI protocols by
replacing separate acquisitions that use fat-saturation and chemical shift
techniques. Furthermore, because all data emanate from a single acquisition,
the resulting diverse image sets are inherently coregistered.
View larger version (111K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A —53-year-old woman with palpable nodule on right outer breast
but no MRI correlation. Note that fat suppression, although subtle, is more
uniform on sagittal T2-weighted iterative decomposition of water and fat with
echo asymmetry and least-squares estimation (IDEAL) image (TR/TE, 6,750/98.8)
(A) than on STIR (6,700/70.3) (B) sequence, especially in
adipose areas surrounding glandular tissue (asterisks, B).
This results in insensitivity of IDEAL to B1 inhomogeneities.
|
|
View larger version (120K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B —53-year-old woman with palpable nodule on right outer breast
but no MRI correlation. Note that fat suppression, although subtle, is more
uniform on sagittal T2-weighted iterative decomposition of water and fat with
echo asymmetry and least-squares estimation (IDEAL) image (TR/TE, 6,750/98.8)
(A) than on STIR (6,700/70.3) (B) sequence, especially in
adipose areas surrounding glandular tissue (asterisks, B).
This results in insensitivity of IDEAL to B1 inhomogeneities.
|
|
View larger version (90K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A —35-year-old man with Crohn's disease and perianal fistula.
Axial fast spin-echo 2D T2-weighted fat-suppressed iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL) image
(TR/TE, 5,117/116) (A) and corresponding non-IDEAL fat-saturated fast
spin-echo image (10,000/119) (B) show fistula track (arrows)
arising from left lateral wall of anus and coursing posteriorly to extend
through internal and external sphincters. Note that fat suppression is less
uniform in traditional chemically fat-suppressed image (asterisks,
B).
|
|
View larger version (91K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B —35-year-old man with Crohn's disease and perianal fistula.
Axial fast spin-echo 2D T2-weighted fat-suppressed iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL) image
(TR/TE, 5,117/116) (A) and corresponding non-IDEAL fat-saturated fast
spin-echo image (10,000/119) (B) show fistula track (arrows)
arising from left lateral wall of anus and coursing posteriorly to extend
through internal and external sphincters. Note that fat suppression is less
uniform in traditional chemically fat-suppressed image (asterisks,
B).
|
|
In the following sections, we illustrate applications of the IDEAL
technique in specific scenarios commonly observed in clinical body MRI.
Hepatic Steatosis
Hepatic steatosis, or fatty liver, is a term applied to a wide spectrum of
conditions histologically characterized by triglyceride accumulation in
hepatocytes. Its prevalence in the general population is approximately
20–30%, which is higher in patients with hyperlipidemia, obesity, or a
history of alcohol consumption. Other relatively common conditions associated
with fat accumulation in the liver include viral hepatitis and the use of
certain drugs. A variant of nonalcoholic fatty liver disease is nonalcoholic
steatohepatitis, which carries a 10–30% incidence of developing
cirrhosis during the decade after the initial diagnosis
[10]. The coexistence of edema
and fibrosis frequently seen with this disorder can present challenges to CT
and sonographic assessments, and fat quantification with these techniques is
not reliable [11].
Chemical shift MRI may show diffuse and focal fat deposition in the liver.
A signal decrease on opposed-phased images compared with in-phase images
provides a specific diagnosis of fat deposition. However, fat quantification
with opposed-phase imaging is limited because of the nonlinear relationship
between signal intensity and fat concentration. IDEAL imaging provides robust
water–fat separation in the liver, facilitating the visualization of
fat-containing lesions (i.e., adenomas, hepatocellular carcinoma,
myelolipoma), visualization of fat deposition (Figs.
5A,
5B, and
5C), and the quantification of
fat in the liver [12].
View larger version (127K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5A —46-year-old woman with nonalcoholic steatohepatitis. All
images were obtained from single 20-second acquisition (TR/TE, 6.9/2). Note
evident signal decrease between in-phase (A) and opposed-phase
(B) iterative decomposition of water and fat with echo asymmetry and
least-squares estimation (IDEAL) images, with some sparing of subcapsular
anterior parenchyma (arrows, B).
|
|
View larger version (126K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5B —46-year-old woman with nonalcoholic steatohepatitis. All
images were obtained from single 20-second acquisition (TR/TE, 6.9/2). Note
evident signal decrease between in-phase (A) and opposed-phase
(B) iterative decomposition of water and fat with echo asymmetry and
least-squares estimation (IDEAL) images, with some sparing of subcapsular
anterior parenchyma (arrows, B).
|
|
View larger version (122K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5C —46-year-old woman with nonalcoholic steatohepatitis. All
images were obtained from single 20-second acquisition (TR/TE, 6.9/2). Fatty
deposition is also clearly seen on IDEAL fat-only image, in which signal is
much higher in liver than in spleen. Note that spared area appears to have
lower signal (arrowheads), as expected in latter fat-only image.
Water-only image is not shown.
|
|
Adrenal Adenoma
Adrenal adenomas are the most common lesion of the adrenal gland and are
frequently seen as incidental lesions on cross-sectional imaging.
Pathologically, adrenal adenomas are characterized by the presence of various
amounts of intracytoplasmic lipids. Other features commonly used to support
the diagnosis of adrenal adenoma are size, lack of invasiveness, and
enhancement pattern. Detection of subvoxel fat in an adrenal lesion is the
basis for a specific diagnosis of adenoma on MRI
[13]. IDEAL imaging may
facilitate this diagnosis by showing fat in the adrenal lesion, particularly
small lesions in which partial volume with the retroperitoneal fat limits the
interpretation of chemical shift images (Figs.
6A,
6B, and
6C).
View larger version (116K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6A —49-year-old woman with right adrenal adenoma. Note high
signal indicating fat in the lesion (arrow) on the axial T1-weighted
iterative decomposition of water and fat with echo asymmetry and least-squares
estimation (IDEAL) fat-only image.
|
|
View larger version (116K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6B —49-year-old woman with right adrenal adenoma. The presence of
fat can also be inferred from signal decrease between in-phase (B) and
opposed-phase (C) images. IDEAL water-only image is not shown (TR/TE,
6.1/2.2).
|
|
View larger version (132K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 6C —49-year-old woman with right adrenal adenoma. The presence of
fat can also be inferred from signal decrease between in-phase (B) and
opposed-phase (C) images. IDEAL water-only image is not shown (TR/TE,
6.1/2.2).
|
|
Renal Angiomyolipoma
Renal angiomyolipomas are the most com mon benign renal neoplasm. They are
composed of varying amounts of fat, smooth muscle, and thick-walled blood
vessels. Although all three tissue elements may be present, these tumors may
be composed of only one of these components (Figs.
7A,
7B,
7C, and
7D). Calcification and
necrosis are rare, but hemorrhage is frequent. Most angiomyolipomas are
sporadic (80–90%), although multiple angiomyolipomas are common in
patients with tuberous sclerosis. Although most are incidentally detected,
some patients present with acute flank pain caused by spontaneous
retroperitoneal hemorrhage.
View larger version (105K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7A —70-year-old man with right renal angiomyolipoma. Lesion (L)
consists of fat as shown in gradient-recalled echo T1-weighted iterative
decomposition of water and fat with echo asymmetry and least-squares
estimation (IDEAL) fat-only image (TR/TE, 6.1/2.2).
|
|
View larger version (104K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7C —70-year-old man with right renal angiomyolipoma. In-phase
(C) and opposed-phase (D) images show india ink artifact at
boundary with renal parenchyma (arrowhead, D) and no clear
signal decrease in mass because it is predominantly macroscopic fat.
|
|
View larger version (116K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 7D —70-year-old man with right renal angiomyolipoma. In-phase
(C) and opposed-phase (D) images show india ink artifact at
boundary with renal parenchyma (arrowhead, D) and no clear
signal decrease in mass because it is predominantly macroscopic fat.
|
|
A confident diagnosis of angiomyolipoma can be made on cross-sectional
imaging when fat is unequivocally shown in a renal mass
[14]. Differentiation of
angiomyolipomas from hyperintense renal cysts with hemorrhagic or
proteinaceous contents is best achieved by specifically showing fat in the
lesion [14].
Ovarian Teratoma
Ovarian teratomas are the most common benign ovarian neoplasm
[15]. They comprise a variety
of histologic subtypes, with mature cystic teratoma (i.e., dermoid cyst) being
the most common. Mature tissues of ectodermal, mesodermal, and endodermal
origin are typically present. Depiction of fat in an ovarian mass is virtually
diagnostic of dermoid, found in 93% of these cases
[15]. A floating mass of hair
or debris can sometimes be identified at the fat–aqueous fluid
interface. Distinction between an ovarian dermoid, a cyst that contains
hemorrhagic or proteinaceous fluid, and endometriomas is best accomplished
when fat is unequivocally shown in the lesion
[15]. IDEAL imaging can
characterize these masses (Figs.
8A,
8B,
8C, and
8D) and is particularly
helpful in lesions with small amounts of fat in which anatomic coregistration
of the non–fat-saturated and fat-saturated images is critical.
View larger version (151K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8C —48-year-old woman with ovarian dermoid. In-phase (C)
and opposed-phase (D) images are shown, and india ink artifact is
clearly seen at water–fat interfaces (arrowhead, D).
Note also uterine enlargement and nabothian cyst in uterine cervix.
|
|
View larger version (157K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 8D —48-year-old woman with ovarian dermoid. In-phase (C)
and opposed-phase (D) images are shown, and india ink artifact is
clearly seen at water–fat interfaces (arrowhead, D).
Note also uterine enlargement and nabothian cyst in uterine cervix.
|
|
Soft-Tissue Lipoma
Soft-tissue lipomas account for almost 50% of all soft-tissue tumors.
Radiologic evalu ation is diagnostic in up to 71% of cases. These lesions
appear identical to subcutaneous fat on CT and MRI and may contain thin septa.
Soft-tissue lipomas can be categorized as superficial or deep, with
superficial lipomas being subcutaneous and common (Figs.
9A,
9B,
9C, and
9D).
View larger version (142K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9A —60-year-old woman with subcutaneous lipoma in right
anterosuperior chest wall. Lump (L) is fat-containing lesion as shown in axial
single-shot T2-weighted fast spin-echo images without (TR/TE, 2,401/306)
(A) and with (2,429/306) (B) fat suppression. Note some regions
of poor fat suppression in posterior area (arrowhead, B).
|
|
View larger version (133K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9B —60-year-old woman with subcutaneous lipoma in right
anterosuperior chest wall. Lump (L) is fat-containing lesion as shown in axial
single-shot T2-weighted fast spin-echo images without (TR/TE, 2,401/306)
(A) and with (2,429/306) (B) fat suppression. Note some regions
of poor fat suppression in posterior area (arrowhead, B).
|
|
View larger version (113K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 9C —60-year-old woman with subcutaneous lipoma in right
anterosuperior chest wall. Thin capsule and septation (arrow) in
lesion are better appreciated on axial gradient-recalled echo T1-weighted
iterative decomposition of water and fat with echo asymmetry and least-squares
estimation (IDEAL) fat-only image (7/2).
|
|
Conclusion
MR sequences that allow suppression or separation of fat signal are
important for two major reasons: Suppression of the signal from normal adipose
tissue decreases chemical shift artifact and better depicts uptake of contrast
material; and it allows tissue characterization, which is a clear advantage of
MRI over other imaging techniques.
The IDEAL technique—and the original Dixon technique
[3]—is based on
decomposing fat and water signals to discriminate between fat and water
protons according to their resonant frequency difference, or chemical shift,
to obtain these two components as two separate images.
IDEAL provides uniform and reliable fat suppression throughout the body,
including the head and neck, breast, heart, abdomen, and extremities.
In conclusion, IDEAL is a promising imaging technique that provides uniform
and reliable fat suppression with the potential to simplify body MR
protocols.
References
- Delfaut EM, Beltran J, Johnson G, Rousseau J, Marchandise X, Cotten
A. Fat suppression in MR imaging: techniques and pitfalls.
RadioGraphics 1999;19
: 373-382[Abstract/Free Full Text]
- Krinsky G, Rofsky NM, Weinreb JC. Nonspecificity of short inversion
time inversion recovery (STIR) as a technique of fat suppression: pitfalls in
image interpretation. AJR 1996;166
: 523-526[Abstract/Free Full Text]
- Dixon WT. Simple proton spectroscopic imaging.
Radiology 1984;153
: 189-194[Abstract/Free Full Text]
- Reeder SB, Pineda AR, Wen Z, et al. Iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL):
application with fast spin-echo imaging. Magn Reson
Med 2005; 54:636
-644[CrossRef][Medline]
- Glover GH, Schneider E. Three-point Dixon technique for true
water/fat decomposition with B0 inhomogeneity correction. Magn
Reson Med 1991; 18:371
-383[Medline]
- Reeder SB, McKenzie CA, Pineda AR, et al. Water–fat
separation with IDEAL gradient-echo imaging. J Magn Reson
Imaging 2007; 25:644
-652[CrossRef][Medline]
- Pineda AR, Reeder SB, Wen A, Pelc AJ. Cramér-Rao bounds for
three-point decomposition of water and fat. Magn Reson
Med 2005; 54:625
-635[CrossRef][Medline]
- Reeder SB, Markl M, Yu H, Hellinger JC, Herfkens RJ, Pelc NJ.
Cardiac cine imaging with IDEAL water–fat separation and steady-state
free precession. J Magn Reson Imaging2005; 22:44
-52[CrossRef][Medline]
- Yu H, Reeder SB, McKenzie CA, et al. Single acquisition
water–fat separation: feasibility study for dynamic imaging.
Magn Reson Med 2006;55
: 413-422[CrossRef][Medline]
- Clark JM, Diehl AM. Nonalcoholic fatty liver disease: an
underrecognized cause of cryptogenic cirrhosis. JAMA2003; 289:3000
-3004[Abstract/Free Full Text]
- Hamer OW, Aguirre DA, Casola G, Lavine JE, Woenckhaus M, Sirlin CB.
Fatty liver: imaging patterns and pitfalls.
RadioGraphics 2006;26
: 1637-1653[Abstract/Free Full Text]
- Reeder SB, Vu AT, Hargreaves BA, et al. Rapid 3D-SPGR imaging of
the liver with multi-echo IDEAL. In: Proceedings of the
International Society of Magnetic Resonance in Medicine. Seattle,
WA: ISMRM, 2006
- Krebs TL, Wagner BJ. MR imaging of the adrenal gland:
radiologic–pathologic correlation. RadioGraphics1998; 18:1425
-1440[Abstract]
- Bosniak MA, Megibow AJ, Hulnick DH, Horii S, Raghavendra BN. CT
diagnosis of renal angiomyolipoma: the importance of detecting small amounts
of fat. AJR 1988;151
: 497-501[Abstract/Free Full Text]
- Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: tumor types
and imaging characteristics. RadioGraphics2001; 21:475
-490[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
Top
Abstract
Introduction
