Sep 15, 1995 - 77. Retropenitoneum. Well differentiated. (lipoma. Myxoid like). Images Obtained. CT. MR. UE and CE. Ti- and T2-WSEI. 5. 46. Mesentery. 6. 47.
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829
CT and MR Imaging Li posarcoma
Tonsok Kim1’2 Murakami1 Hiromichi 0i2 Kyo Tsuda1 Masaki Matsushita2 Kaname Tomoda1 Hanuki Fukuda3 Hironobu Nakamuna1
Takamichi
of Abdominal
OBJECTIVE. CT and MR images were reviewed to correlate the histologic subtypes of abdominal liposarcoma wIth the radiologic findings. SUBJECTS AND METHODS. Ten patients with liposarcoma who underwent CT or MR imaging before surgery were included in this study. CT and MR imaging findings for these patients were compared retrospectively with histologic findings. RESULTS. Major histologic subtypes found in our group of patients were five welldifferentiated, three myxoid, one pleomorphic, and one round-cell liposarcomas. The well-differentiated subtype consisted of lipoma-like and/or sclerosing components. The predominant attenuation and signal intensity characteristics of the lipoma-like components on CT and MR images resembled those of fat, whereas the predominant attenuation
and
signal
intensity
characteristics
of the
sclerosing
components
resem-
bled those of muscle. The myxoid subtype showed, on unenhanced images, predominant attenuation and signal intensity characteristics that resembled those of water; on contrast-enhanced images, this subtype showed gradual reticular enhancement. The appearance of the round-cell and pleomorphic subtypes was that of heterogeneous, nonfatty tumors. Their characteristics were indistinguishable from those of other malignant soft-tissue masses. CONCLUSION. Each histologic subtype of abdominal Ilposarcoma showed different CT attenuation or MR imaging signal Intensity characteristics. A clear understanding of these findings should prove helpful in the diagnosis of liposarcoma. AJR
1996;166:829-833
Liposancoma is a malignant tumor of mesenchymal origin. Liposarcoma is one of the most common primary neoplasms in the retnopenitoneum, whereas primary mesenteric and primary penitoneal liposancomas are rare [i-3]. It is often difficult to use imaging findings to diagnose abdominal liposancoma when it lacks a fat component. Histologically, liposarcomas are classified as well-differentiated, myxoid, pleomonphic,
Received September 1 5, 1995; accepted after revision November 22, 1995. 1 Department of Radiology, Osaka University Medical School, 2-2 Yamadaoka, Suita City, Osaka 565, Japan. Address correspondence to T. Kim. 2 Department of Radiology, Osaka Teishin Hospital, Osaka
City, Osaka
3Department Medical
School,
of Suita
0361-803X/96/1664-829 © American Roentgen
543, Japan.
Pathology,
Osaka
City, Osaka Ray Society
University
565, Japan.
and
round-cell
subtypes
[4].
In addition,
well-differentiated
tumors
are
subdi-
vided into four types: lipoma like, sclerosing, inflammatory, and dediffenentiated. Prognosis for patients with liposarcoma varies on the basis of the histologic subtype [1 5, 6]. Well-differentiated liposancoma is considered a low-grade malignancy; myxoid liposarcoma is considered an intermediate-grade malignancy; and pleomorphic and round-cell liposarcomas are considered high-grade malignancies with high rates of local recurrence and metastasis. Reports have correlated imaging findings and histologic subtypes of liposarcoma in the extremities [5, 7] but, to our knowledge, no such report exists for abdominal liposarcoma. For this study, we retrospectively reviewed and compared CT and MR imaging findings for abdominal liposancomas with pathologic findings for resected specimens to clearly identify the imaging appearance of each specific histologic subtype of abdominal liposarcoma. ,
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Subjects
and
tion) or fast low-angie
Methods
Ten patients with liposarcoma in the abdominal region who underwent CT examination before resection between i 990 and 1995 were included in this study (Table 1). Seven of the 10 patients also underwent MR imaging examination before surgery. All CT and MR imaging examinations were performed within 1 month of surgery. All patients were women and were 43-77 years old (mean, 55 years old). The primary sites of the liposarcomas were the retnoperitoneum in seven patients, the mesentery in one, the mesosigmoid in one, and the peritoneum in one. The liposarcomas were histologically identified
by complete The
AJR:166, April 1996
KIM ETAL.
830
resections
liposarcomas
in nine patients
were
classified
into
and by open biopsy in one. histologic
subtypes
on the
basis of the most aggressive cellular component of the tumor. CT examination was performed with a Somatom Plus scanner (Siemens,
Erlangen,
tnic-Yokogawa
Germany),
Medical,
Tokyo,
a Quantex Japan),
scanner
(General
or a High-Speed
mmol
of
gadopentetate
Japan)
dimeglumine
(Magnevist;
per kg of body weight.
Nihon
Schening,
MR imaging
before and after administration of gadopentetate dimeglumine was performed on two of the four patients. The gradient-echo MR images
were obtained
with fast multiplanar
tion in the steady
TABLE
Patient
1
state
1 : Abdominal
spoiled gradient-recalled [TRITE];
Liposarcoma
Age (Yr)
65
(160/2.5
Primary
flip angle,
[TRITE];
flip angle,
ated for the six trast-enhanced Predominant sified into four images: group
patients who underwent both unenhanced and conCT imaging. MR signal intensity characteristics of tumors were clasgroups on the basis of both Ti- and T2-weighted A showed signal intensity less than that of muscle;
B showed
signal
intensity
equal
to that of muscle;
group
acquisi-
60#{176}; one excita-
fat; and group D showed fat. Tumor enhancement
Mesosigmoid
Histologic Subtype Seen Majority of Patients
Well differentiated
spin-echo
images also were evaluated for the four patients who both unenhanced and contrast-enhanced MR imaging.
MR
underwent Results
Histologic
Subtypes
In this study, the histologic subtypes of the iO liposarcomas were as follows: five well differentiated (either lipoma like or lipoma like and sclerosing), three myxoid, one pleomorphic, and one round cell. Liposancomas of six patients were of only one histologic subtype, whereas those of the other four patients included minor components of another histologic subtype (Table i). Of the five well-differentiated liposarcomas, one was a lipoma-like subtype with calcifications, three were lipoma-like
subtypes
with
sclerosing
components,
and
was a lipoma-like subtype with a myxoid subtype component. Of the three myxoid liposarcomas, solely myxoid, one included a sclerosing subtype
in
Images Obtained
Histologic Subtype Seen in Minority of Patients
CT
54
Aetroperitoneum
Well differentiated
MR
(lipoma
UE and CE
Ti- and T2-WSEI
(lipoma
UE and CE
Not obtained
(lipoma
CE
Not obtained
UEandCE
Ti-, 12-, and CETi-WSE1
CE
Ti-and
CE
Ti-,
like and sclerosing)
3
65
Retropenitoneum
Well differentiated like and sclerosing)
4
77
Retropenitoneum
Well differentiated
(lipoma
5
46
Mesentery
6
47
Penitoneum
like) Well differentiated (lipoma like and sclerosing) Myxoid
7
43
Retropenitoneum
Myxoid
Myxoid
Well differentiated (sclerosing) Well differentiated
(lipoma
UE and
CE
Ti-,
like)
8
63
Aetroperitoneum
Myxoid
9
43
Retropenitoneum
Pleomorphic
10
49
Retropenitoneum
Round
Note-All
patients
T2-WSEI 12-,
and
CET1-WSEI
12-,
and
CE Ti-WSEI
and gradient
were
women.
UE
=
unenhanced,
cell
CE
Ti-, T2-, and CETi-WSEI
CE
Ti-and
UE and =
contrast enhanced,
T1-WSEI
=
Ti-weighted
echo
UEandCE
and gradient Well differentiated (lipoma like and sclerosing)
CE
spin echo, T2-WSEI
echo
T2-WSEI
Not obtained =
T2-weighted
one
as a minor one was as a minor
like)
2
C
signal intensity equal to or greaterthan that of patterns on contrast-enhanced Ti -weighted
Patients
Site
60#{176};
showed signal intensity greater than that of muscle but less than that of
Advantage
Gradient-echo
(150/4
group 1 showed attenuation approximately equal to that of fat; group 2 showed attenuation greater than that of fat but less than that of muscle; and group 3 showed attenuation equal to or greater than that of muscle. Tumor enhancement patterns also were evalu-
group
Elec-
scanner (General Electric Medical Systems, Milwaukee, WI). Contrast-enhanced CT images were obtained for all 10 patients, and unenhanced CT images were obtained for six patients (Table 1). MR imaging examination was performed with a 1 .5-T scanner (Signa [General Electric Medical Systems] or Magnetom [Siemens]) or a 1 .0-T scanner (Magnetom Impact; Siemens) that used superconducting magnet systems. Ti -weighted (400-600/11-15/2 [TR range/TE range/excitations]) and T2-weighted (1800-2000/80/2 [TR range/TE/excitations]) spin-echo MR images were obtained for all seven patients who underwent MR imaging examination. Presaturation pulses were used for the Tiand 12-weighted spin-echo images, and gradient moment nulling was used for the T2-weighted spin-echo images. Contrast-enhanced Ti -weighted spin-echo images were obtained for four patients after IV administration of 0.1
Osaka,
shot acquisition
one excitation). Unenhanced CT attenuation was classified into one of three groups on the basis of the predominant attenuation of the tumor:
spin echo.
AJR:166,
April
component, minor
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and
one
and
round-cell
Correlation
included
The
component.
lipoma-like The
CT AND
1996
sclerosing
Between
Well-differentiated nents: lipoma-like components seen
a lipoma-like
pleomonphic
liposancoma
Imaging
MR IMAGING
subtypes
as
had no minor
Findings
liposancoma and sclenosing in seven of our
subtype
liposarcoma minor
as
a
included components.
components.
and Histologic can
OF ABDOMINAL
have
subtypes. The patients showed
Findings
two
compo-
lipoma-like low atten-
uation on CT images and high signal intensity on Ti- and T2-weighted spin-echo MR images; these findings nesembled those for subcutaneous fat (Figs. 1 and 2). The sclenosing components seen in five patients, on the other hand, showed CT attenuation or MR signal intensity that approxi-
LIPOSARCOMA
mated the characteristics of muscle (Fig. 2). On contrastenhanced CT images, septa within lipoma-like components were enhanced, and sclerosing components were enhanced homogeneously. Myxoid components seen in four patients showed predominant regions in which CT attenuation was less than that of muscle and MR signal intensity was similar to that of waterhypointense compared with muscle on Ti -weighted spin-echo images and hypenintense compared with fat on T2-weighted spin-echo images. T2-weighted spin-echo MR images also indicated septa of low signal intensity within these components. Before contrast enhancement, myxoid components showed CT attenuation and MR signal intensity similar to that of water. After contrast enhancement, gradual reticular enhancement was seen within the myxoid components (Fig.
Fig. 1 .-65-year-oId woman with lipoma-like, well-differentiated Ilposarcoma orIginating from mesosigmoid. A, Contrast-enhanced CT Image shows huge fatty tumor with septa and calcificatlons. Sigmoid colon (thin arrows) and inferior mesenteric and vein (thick arrow) are surrounded by tumor. B, Ti-weighted (600/12/2 [TRITE/excItations]) spin-echo MR image shows tumor to be predominantly isointense in relation to subcutaneous C, T2-weighted (1800/80/2) spin-echo MR Image also shows tumor to be predominantly Isointense in relation to subcutaneous fat.
Fig. 2-43-year-old A, Contrast-enhanced
83i
artery fat.
woman with pleomorphic liposarcoma having well-differentiated subtypes (lipoma like and sclerosing) as minor components. CT image shows huge mass displacing left kidney in left retroperitoneum. Lipoma-like component appears as area of fatty attenuation. Round region of pleomorphic component (thick arrows) and sclerosing components (thin arrows) infiltrate lipoma-like component and appear as areas of less fatty attenuation. Note that it is impossible to differentiate pleomorphic component from sclerosing components by attenuation on this CT image. B, Ti -weighted (600/i 5/2 [TRITE/excitations]) spin-echo MR image shows pleomorphic component (thick arrows) and sclerosing components (thin arrows) to be isointense in relation to muscle. Lipoma-like component appears isointense in relation to subcutaneous fat. C, T2-weighted (1800/80/2) spin-echo MR image shows that pleomorphic component has high signal intensity, like that of subcutaneous fat (thick arrows), whereas sclerosing components have low signal Intensity, like that of muscle (thin arrows). Lipoma-like component appears isointense in relation to subcutaneous fat.
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AJR:166, April 1996
KIM ETAL.
832
Fig. 3.-63-year-old woman with myxoid llposarcoma In retroperitoneum. A, Unenhanced image shows tumor (arrows) to be hypoattenuated in relation
to muscle. Reticular pattern is seen within tumor. B, Contrast-enhanced CT scan obtained 1 mm after injection of contrast medium. Tumor shows gradual reticular enhancement (arrows). C, Contrast-enhanced CT scan obtained 3 mm after injection of contrast medium. Tumor shows gradual retlcular enhancement (arrows). 0, Ti-weighted (600115/2 [TRITE/excItations]) spin-echo MR Image shows tumor to be hypomntense In relatIon to muscle. E, T2-welghted (I 800/80/2) spin-echo MR image shows tumor to be predominantly hyperintense In relation to subcutaneous fat and also shows septa (arrows) with low signal intensIty. F, Contrast-enhanced Ti -weighted (600/1 5/2) spIn-echo MR image shows reticular enhancement in tumor.
3). A large area of one myxoid liposancoma enhanced markedly. Although myxoid components appeared to be cystic lesions before contrast enhancement, they appeared to be solid lesions after contrast enhancement. The pleomorphic component seen in one patient showed CT attenuation approximating that of muscle. Signal intensity was equal to that of muscle on Ti -weighted spin-echo MR images and equal to that of fat on T2-weighted spin-echo MR images. Thus, the pleomorphic component that resembled the sclenosing subtype on the basis of CT attenuation differed from it on the basis of MR signal intensity (Fig. 2). The patient with round-cell liposancoma had multiple tumors. CT attenuation of round-cell components approximated muscle attenuation in the retnopenitoneum, as did CT attenuation
of the
sclerosing
subtype.
However,
although
the
Reports have correlated imaging findings and histologic subtypes of liposarcoma in the extremities [5, 7]. Liposarcomas sometimes
include
multiple
histologic
subtypes
within
the same
lesion [5]. Such histologic subtypes are usually classified on the basis of the most aggressive cellular component. However, the CT and MR appearances of liposarcomas can vary according to the combination of these histologic subtypes [5, 7]. Variable CT attenuation or MR signal intensity throughout a lesion may result from different histologic tissue subtypes found in that lesion. Thus, histologic subtypes should be considered for parts of a lesion that show variable appearances on CT and MR images. Well-differentiated liposarcomas in the extremities have been described as tumors with CT attenuation and MR signal intensity equal to those of fat. These tumors also can have thickened, irregular septa and minor nodular components with
sclerosing components were relatively homogeneous, the round-cell subtype appeared heterogeneous, with irregular hypoattenuation on contrast-enhanced CT images (Fig. 4). MR images of the round-cell subtype were not available. The findings for the tumors that had one on two histologic subtype components appeared to be a combination of the characteristic findings for the individual subtypes.
Discussion
Liposarcoma may anise in any region of the body that contains fat [1]. Liposarcoma is one of the most common malignant tumors in the netropenitoneum but is rare in the mesentery and in the penitoneum. Although liposarcoma has been reported to occur without a sex predilection [i], the patients that we studied were all women.
Fig. 4.-49-year-old woman with round-cell Ilposarcoma in retroperitoneum. Contrast-enhanced CT image shows multiple heterogeneous nonfatty masses In retroperltoneum (white arrows). Invasion into left kidney also Is seen (black arrows).
AJR:166,
1996
CT AND
MR IMAGING
OF ABDOMINAL
on CT scans approximating that of skeletal muscle. Focal areas of well-differentiated liposarcomas on T2-weighted spin-echo images may have a signal that is hypenntense relative to that offat [5]. The lipoma-like component, which is one of the well-differentiated subtypes, usually contains fat. Fat within the tumor may lead to a diagnosis of liposarcoma, although abdominal tumors with fat are not always liposarcomas [8, 9]. It has been suggested that the greaten the fat component within a liposancoma, the lower the tumor should be graded histologically [7, 10]. The sclerosing component, which also is one of the well-differentiated subtypes, showed CT attenuation and MR signal intensity that approximated the characteristics of muscle. Less fatty liposarcomas composed of myxoid, pleomorphic, on round-cell subtypes have been reported [5]. The sclerosing subtype also could produce a nonfatty liposarcoma. In this study, myxoid liposarcomas showed CT attenuation less than that of muscle and a homogeneous MR signal intensity similar to that of waten-hypointense Compared with muscle on Ti-weighted spin-echo images and hyperintense compared with fat on T2-weighted spin-echo images-like previously reported Iiposarcomas in the extremities [5, 7]. On CT and MR images, although the myxoid liposarcomas of our patients appeared to be cystic lesions before contrast enhancement, they appeared to be solid lesions showing gradual reticular enhancement after contrast enhancement. These findings, which we believe result from the myxomatous interstitial content and fibrous tissue within this tumor subtype, may prove useful in differentiating such tumors from other benign abdominal Cystic tumors or malignant necrotic tumors (e.g., leiomyosarcoma). Round-cell and pleomorphic liposarcomas were heterogeneous, nonfatty tumors, as previously described [5]. Their characteristics were indistinguishable from those of other malignant soft-tissue masses (e.g., leiomyosarcoma and malignant fibrous histiocytoma) [ii]. We found that lipoma-like and myxoid liposancomas showed characteristic CT and MR appearances. Sclerosing, pleomorphic, and round-cell liposarcomas showed similar CT attenuaattenuation
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April
tion.
LIPOSARCOMA
However,
the
MR
833
signal
intensity
of
the
sclerosing
component was different from that of the pleomorphic component on T2-weighted spin-echo images. These differences may allow differentiation of the sclerosing subtype, typical of lowgrade malignancy, from the pleomorphic subtype, typical of high-grade malignancy. However, further study is needed because our study group included few cases of these subtypes. In conclusion, we emphasize that a clear understanding of the imaging appearances of histologic subtypes of liposarcoma should be helpful for diagnosis and for predicting the prognosis for a patient with liposarcoma because histologic subtypes affect the prognosis.
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This article has been cited by: 1. Elena P. Scali, Tracy M. Chandler, Eric J. Heffernan, Joseph Coyle, Alison C. Harris, Silvia D. Chang. 2015. Primary retroperitoneal masses: what is the differential diagnosis?. Abdominal Imaging 40, 1887-1903. [CrossRef] 2. C. Morosi, S. Stacchiotti, A. Marchianò, A. Bianchi, S. Radaelli, R. Sanfilippo, C. Colombo, C. Richardson, P. Collini, M. Barisella, P.G. Casali, A. Gronchi, M. Fiore. 2014. Correlation between radiological assessment and histopathological diagnosis in retroperitoneal tumors: Analysis of 291 consecutive patients at a tertiary reference sarcoma center. European Journal of Surgical Oncology (EJSO) 40, 1662-1670. [CrossRef] 3. Brian C. Allen, Keyanoosh Hosseinzadeh, Shadi A. Qasem, Adam Varner, John R. Leyendecker. 2014. Practical Approach to MRI of Female Pelvic Masses. American Journal of Roentgenology 202:6, 1366-1375. [Abstract] [Full Text] [PDF] [PDF Plus] 4. C. Avancès, J. Rigaud, P. Camparo, X. Durand, P. Sèbe, A. Fléchon, T. Murez, P. Coloby, M. Soulié. 2013. Contribution 2013 du CCAFU au référentiel INCa : Sarcomes du rétropéritoine. Progrès en Urologie 23, S161-S166. [CrossRef] 5. Adarsh Vijay, Lakshmi Ram. 2013. Retroperitoneal Liposarcoma. American Journal of Clinical Oncology 1. [CrossRef] 6. Joseph M. Bestic, Mark J. Kransdorf, Lawrence M. White, Mellena D. Bridges, Mark D. Murphey, Jeffrey J. Peterson, Hillary W. Garner. 2013. Sclerosing Variant of Well-Differentiated Liposarcoma: Relative Prevalence and Spectrum of CT and MRI Features. American Journal of Roentgenology 201:1, 154-161. [Abstract] [Full Text] [PDF] [PDF Plus] 7. Ana Bermejo, Teresa Díaz De Bustamante, Alberto Martinez, Roberto Carrera, Elena Zabía, Palmira Manjón. 2013. MR Imaging in the Evaluation of Cystic-appearing Soft-Tissue Masses of the Extremities. RadioGraphics 33, 833-855. [CrossRef] 8. Yoshikazu Tsuchiya, Kohki Takeda, Takashi Nikaido, Takayuki Yamada, Koho Akimaru, Eiji Uchida. 2013. A Case of Liposarcoma Developing in the Ligamentum Teres Hepatis Concomitant with Rectosigmoid Cancer. Nihon Ika Daigaku Igakkai Zasshi 9, 194-197. [CrossRef] 9. Hyun Suk Cho, Ji Young Woo, Hye-Suk Hong, Ik Yang, Yul Lee, Ah Young Jung, Dae Hyun Yang, Ji Won Kim, Jeong Won Kim. 2013. Imaging Findings of Angiomyxolipoma of the Spermatic Cord Mimicking Inguinal Hernia. Korean Journal of Radiology 14, 218. [CrossRef] 10. Carlo Grifasi, Armando Calogero, Nicola Carlomagno, Severo Campione, Francesco D’Armiento, Andrea Renda. 2013. Intraperitoneal dedifferentiated liposarcoma showing MDM2 amplification: case report. World Journal of Surgical Oncology 11, 305. [CrossRef] 11. Dongjun Jeong, Sang Won Kim. 2012. Dedifferentiated subserosal liposarcoma of the jejunum: sonographic and computed tomographic findings with pathologic correlation. Clinical Imaging 36, 390-393. [CrossRef] 12. Ajit H. Goenka, Shetal N. Shah, Erick M. Remer. 2012. Imaging of the Retroperitoneum. Radiologic Clinics of North America 50, 333-355. [CrossRef] 13. Case 72 147-148. [CrossRef] 14. Charles P. Mullan, Rachna Madan, Beatrice Trotman-Dickenson, Xiaohua Qian, Francine L. Jacobson, Andetta Hunsaker. 2011. Radiology of Chest Wall Masses. American Journal of Roentgenology 197:3, W460-W470. [Abstract] [Full Text] [PDF] [PDF Plus] 15. C. Avancès, P. Camparo, F. Quenet, X. Durand, S. Culine, P. Sèbe, M. Soulié, J. Rigaud. 2011. Histoire naturelle et prise en charge des sarcomes du rétropéritoine : état des lieux par le comité de cancérologie de l’association française d’urologie sous comité Organes génitaux externes. Progrès en Urologie 21, 441-447. [CrossRef] 16. N. Boucher, C. Brochart, S. Blanpain, C. Chivot, B. Robert, B. Szitkar, D. Chatelain, T. Yzet, H. Deramond. 2011. À propos d’un cas rare de myélolipome extrasurrénalien. Journal de Radiologie 92, 50-53. [CrossRef] 17. E. Ciortan, L. Carra. 2010. Abdominal mass as the first sign of follicular lymphoma B of mesentery: Case report. Journal of Ultrasound 13, 123-125. [CrossRef] 18. Ruchika Gupta, Alok Sharma, Raman Arora, Mukund P. Kulkarni, T. K. Chattopadhaya, Manoj K. Singh. 2010. WellDifferentiated Mesenteric Liposarcoma with Osseous Metaplasia: A Potential Diagnostic Dilemma for the Pathologist. Journal of Gastrointestinal Cancer 41, 79-83. [CrossRef] 19. Na-young Shin, Myeong-Jin Kim, Jae-Joon Chung, Yong-Eun Chung, Jin-Young Choi, Young-Nyun Park. 2010. The Differential Imaging Features of Fat-Containing Tumors in the Peritoneal Cavity and Retroperitoneum: the Radiologic-Pathologic Correlation. Korean Journal of Radiology 11, 333. [CrossRef] 20. Rupan Sanyal, Erick M. Remer. 2009. Radiology of the Retroperitoneum: Case-Based Review. American Journal of Roentgenology 192:6_supplement, S112-S117. [Abstract] [Full Text] [PDF] [PDF Plus] 21. Rupan Sanyal, Erick M. Remer. 2009. Radiology of the Retroperitoneum: Self-Assessment Module. American Journal of Roentgenology 192:6_supplement, S118-S121. [Abstract] [Full Text] [PDF] [PDF Plus]
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