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287
The Differential Imaging
Diagnosis
of Ringed
Peter F. Hahn,1 David D. Stark,1 Sanjay Saini,1 Jack Wittenberg,1 and Joseph T. Ferrucci1
Ernst
Rummeny,1’2
Lesion morphology complements lesion signal intensity in the differential diagnosis of liver masses on MR images. This essay is intended to show how one morphologic feature, a ringed appearance, can be used to narrow the differential diagnosis of a focal hepatic lesion. A ring is a radially symmetric peripheral zone with signal intensity different from that of the center on Ti -weighted, 225-500/1 3-28 (TR/TE), and T2-weighted, 2000-2800/32-i 80, MR images. Sometimes there are several layers of rings. The ring may be a component of the lesion itself or may be a response of liver tissue to the presence of the adjacent lesion.
Capsules
in Primary
Fibrous carcinomas
capsules are present in 24-42% of hepatocellular (Fig. 1), but occasionally also in adenomas (Fig.
2) [1]. The capsule
Liver
Tumors
has low signal intensity
because
July
18, 1 989; accepted
after revision
September
Anular
Guillermo
Features
Ehizondo,1’3
Essay
Lesions
in MR
Ralph
Weissleder,1
of Metastases
Hepatic metastases patterns on T2-weighted
may exhibit either of two different images [2]. A peritumoral “halo”
3) of high signal intensity
is seen in 13% of metastases
ring (Fig.
and
in 29% of malignant primary liver tumors. In 27% of metastases, liquefaction necrosis can be seen as a central zone of especially high signal intensity, giving the lesion a “target” appearance, sometimes in conjunction with a peritumoral halo (Fig. 4). On Ti -weighted images the increased water in necrotic tissue appears as a central zone of especially low signal intensity. The presence of a penitumoral halo or a target on heavily T2-weighted images distinguishes metastases from cavernous hemangiomas (Fig. 5).
Hematomas
of colla-
gen content. A capsule is best seen on Ti -weighted images as a thin peripheral rim of low signal intensity separating tumor tissue from normal liver. T2-weighted images show the capsule less readily because of reduced signal-to-noise ratio. Sometimes, displaced blood vessels around a space-occupying hepatic mass mimic the appearance of a capsule.
Received
Hepatic
Pictorial
Rings in subacute hematomas are mediated by iron-contaming products of hemoglobin degradation. An outer ring has very low signal intensity on all pulse sequences, is sometimes incomplete, and has been attributed to magnetic field inhomogeneity induced by iron particles, either hemosiderin or ferritin. Inside the dark outer ring is a bright ring of very
1 1 , 1989.
Presented in part at the annual meeting of the American Roentgen Ray Society, New Orleans, May 1989. This work was supported in part by funds from the American Cancer Fellowship from the Radiological Society of North America (S. Saini). 1 2 3
Society,
JFRA-163
and PDT-326
(D. D. Stark),
and a Research
and Education
Department of Radiology, Harvard Medical School and the Massachusetts General Hospital, Boston, MA 021 14. Address reprint requests to P. F. Hahn. Present address: Institut f#{252}r klinische Radiologie, Westf#{228}lische Wilhelms-Universit#{228}t,D4000 MUnster, Federal Republic of Germany. Present address: Magnetic Resonance Imaging Unit, Hospital Universitario, Monterrey, Nuevo Leon 64460, Mexico.
AJR 154:287-290,
February
1990 0361 -803X/90/1
542-0287
© American
Roentgen
Ray Society
Fund
Downloaded from www.ajronline.org by 201.164.233.125 on 10/23/15 from IP address 201.164.233.125. Copyright ARRS. For personal use only; all rights reserved
288
HAHN
ET AL.
AJR:154,
February
1990
Sz:irMs
I
“
i.aI4e
;I.”
.
Fig. 1.-Hepatocellular carcinoma. Ring in this case is formed by a capsule. A, SE 260/14 MR image obtained at 0.6 T shows capsule as thin peripheral ring (arrows) signal intensity between tumor and surrounding liver. Fatty degeneration in tumor shortens increases contrast with capsule. B, T2-weighted MR image (SE 2350/120) shows capsule less distinctiy.
of low Ti and
Fig. 3.-Metastasis with peritumoral halo of increased water in liver tissue around lesion. A, T2-weighted SE 2350/120 MR image shows halo (arrow) of lengthened T2 adjacent to tumor. B, Ti-weighted MR image fails to show zone of increased water around lesion.
short Ti best seen on Ti-weighted images. This ring mdicates the paramagnetic effect of methemoglobin at the periphery of the clot. Hemorrhages associated with hepatic neoplasms rarely exhibit the symmetry found in traumatic hematomas (Fig. 6). ,
Inflammatory
Cysts
Hydatid liver cysts [4] have a cyst wall that resembles the capsule in primary liver tumors. However, contiguous with the very long Ti cyst contents, the capsule is poorly demonstrated on Ti -weighted images. In contrast, T2-weighted images show the capsule as a rim of low signal intensity between the high signal intensity of the fluid cyst and the intermediate signal intensity of surrounding liver (Fig. 7).
Fig. 2.-Encapsulated hepatocellular adenoma. Low-signal-intensity capsule (arrows) on 0.6-T SE 260/14 MR image is indistinguishable from capsule of hepatomas. Decreased density of mobile protons in fibrous tissue accounts for low signal intensity. (Reprinted with permission from Rummeny et al [1].)
Fig. 4.-Metastases shown on MR image at 1.5 T, SE 2000/80. Ring of viable tumor surrounding central necrosis (arrows) gives target appearance. Note peritumoral halo.
Daughter cysts are demarcated from the parent cyst by a wall of low signal intensity. Amebic liver abscesses [5] respond to antibiotic treatment by developing four concentric zones. Both Ti - and T2weighted images are required to show all of them (Fig. 8). The central liquefied abscess is surrounded by inflamed granulation tissue and a band of collagen. A narrow zone of edematous liver forms the perimeter. Edema is not visible on Ti -weighted images. T2-weighted images show the central necrosis and granulation inside and edema outside as hyperintense zones separated by the hypointense collagenous wall. Serial T2-weighted images show progressive resolution of the peripheral hepatic edema after treatment. Peripheral edema may be present around untreated abscesses, but usually it is not symmetric radially; the other ring features are absent or irregular and indistinct prior to therapy.
Downloaded from www.ajronline.org by 201.164.233.125 on 10/23/15 from IP address 201.164.233.125. Copyright ARRS. For personal use only; all rights reserved
Fig. 5.-Unusual cavernous hemangioma, with central cyst. A, SE 260/14 MR image obtained at 0.6 1 shows ring of low-signal-intensity hemangioma tissue (arrow) around long Ti cyst. B, On SE 2000/32 MR image, central zone is visible. C, With more 12-weighting, SE 2000/64, lesion appears homogeneous because both cyst and hemangloma have long T2. (Reprinted with permission from Stark and Bradley [3].)
Fig. 6.-Hematoma from small hepatoma imaged at 1.5 T. A, SE 410/17 TI-weighted MR image best shows bright inner ring (large arrows) of methemoglobin and dark outer ring (small arrows) of iron particle deposition. B, SE 2800/80 MR image does not visualize distinctive bright ring against long 12 of clot. (Courtesy of N. 0. Whltley, Baltimore, MD.)
A
Fig. 7.-Hydatid cyst imaged at 051. A, T2-weighted SE 2000/60 MR image shows low-signal-intensity wall (arrows) around cyst. B, Ti-weighted SE 500/25 MR image does not show wall because low signal intensity of cyst contents C, CT scan resembles Ti-weighted MR Image and shows wall of daughter cyst only. (Courtesy of L-G. Vici, Caracas, Venezuela.)
B
provides
Insufficient
contrast.
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290
HAHN
ET AL.
AJR:154,
February
1990
Fig. 8.-Treated amebic liver abscess, imaged at 0.351. A, Ti-weighted SE 500/28 MR image shows three of four zones found histologically. Central low-signal-intensity cyst is surrounded concentrically by zone of intermediate-signal-intensity granulation tissue (white arrows) and low-signalintensity abscess wall (black arrows). B, On 12-weighted SE 2000/84 MR image, granulation zone is not separately distinguishable from long T2 cyst contents, both enclosed by wall (black arrows). Lesion is surrounded by edematous liver (white arrows), visible only on 12-weighted image. (Reprinted with permission from Elizondo et al. [5].)
B Fig. 9.-Cavernous hemangioma, showing ringed appearance created by IV injection of contrast material. A, Unenhanced SE 2350/180 MR image at 0.6 I shows typical very long 12 of lesion (H). B, Breath-holding Ti-weighted SE 225/13 MR image 12 mm after IV injection of Gd-DTPA, 0.1 mmol/kg (Beriex Laboratories, Wayne, NJ). As contrast material fills hemangioma, peripheral Ti shortening produces irregular zone resembling a ring (arrows).
Discussion
Not every lesion of the histologic types discussed here will present with ringed architecture. However, both Ti - and T2weighted images should be obtained to detect rings associated with hepatic masses, and both Ti - and T2-weighted images should be analyzed to distinguish among the various lesions that can have rings. A bright ring on Ti -weighted images usually indicates hemorrtiage. Melanoma metastases and fatty degeneration in primary liver tumors can be hypenintense compared with normal liver, as can any lesion in the setting of hepatic iron overload. The coincidence of one of these conditions with central necrosis could produce a hyperintense ring. Therefore, the hypointense ring peripheral to the ring of hypenintensity is an important feature of hematomas.
A bright ring on T2-weighted
images
indicates
an increase
tissue water, seen around both inflammatory cysts and malignant neoplasms. The presence of a capsule distinguishes hepatocellular carcinomas and adenomas from metastases and hemangiomas. The ringed appearances of both treated amebic liver abscesses and hydatid cysts are distinctive. Unfortunately, the in
MR appearance of amebic abscess before treatment is nondiagnostic, and little is known about the spectrum of MR presentations of hydatid disease. When MR images show rings in a liver mass, the architectune on Ti - and T2-weighted images may indicate necrosis, a capsule, walls, methemoglobin, iron particle deposition, or increased hepatic tissue water (congestion or edema). Recognition of these histologic features can lead to a tissuespecific diagnosis. With the advent of IV MR contrast agents, ringed features may be enhanced and the list of ringed conditions extended (Fig. 9). REFERENCES 1 . Rummeny E, Weissleder R, Stark DD, et aI. Primary liver tumors: diagnosis by MR imaging. AJR i989;1 52:63-72 2. Wittenberg J, Stark DD, Forman BH, et al. Differentiation of hepatic
metastases
from hepatic hemangiomas
AJR 1988;151 :79-84 3. Stark DD, Bradley WG, Jr, eds. Magnetic
and cysts by using MR imaging. resonance
imaging.
St. Louis:
Mosby, 1988 4. Hoff FL, Aisen AM, Walden ME, Glazer GM. MR imaging in hydatid disease of the liver. Gastrointest Radiol 1987;12:39-42 5. Elizondo G, Weissleder R, Stark DD, et al. Amebic liver abscess: diagnosis and treatment evaluation with MR imaging. Radiology 1987;165:795-800
287
The Differential Imaging
Diagnosis
of Ringed
Peter F. Hahn,1 David D. Stark,1 Sanjay Saini,1 Jack Wittenberg,1 and Joseph T. Ferrucci1
Ernst
Rummeny,1’2
Lesion morphology complements lesion signal intensity in the differential diagnosis of liver masses on MR images. This essay is intended to show how one morphologic feature, a ringed appearance, can be used to narrow the differential diagnosis of a focal hepatic lesion. A ring is a radially symmetric peripheral zone with signal intensity different from that of the center on Ti -weighted, 225-500/1 3-28 (TR/TE), and T2-weighted, 2000-2800/32-i 80, MR images. Sometimes there are several layers of rings. The ring may be a component of the lesion itself or may be a response of liver tissue to the presence of the adjacent lesion.
Capsules
in Primary
Fibrous carcinomas
capsules are present in 24-42% of hepatocellular (Fig. 1), but occasionally also in adenomas (Fig.
2) [1]. The capsule
Liver
Tumors
has low signal intensity
because
July
18, 1 989; accepted
after revision
September
Anular
Guillermo
Features
Ehizondo,1’3
Essay
Lesions
in MR
Ralph
Weissleder,1
of Metastases
Hepatic metastases patterns on T2-weighted
may exhibit either of two different images [2]. A peritumoral “halo”
3) of high signal intensity
is seen in 13% of metastases
ring (Fig.
and
in 29% of malignant primary liver tumors. In 27% of metastases, liquefaction necrosis can be seen as a central zone of especially high signal intensity, giving the lesion a “target” appearance, sometimes in conjunction with a peritumoral halo (Fig. 4). On Ti -weighted images the increased water in necrotic tissue appears as a central zone of especially low signal intensity. The presence of a penitumoral halo or a target on heavily T2-weighted images distinguishes metastases from cavernous hemangiomas (Fig. 5).
Hematomas
of colla-
gen content. A capsule is best seen on Ti -weighted images as a thin peripheral rim of low signal intensity separating tumor tissue from normal liver. T2-weighted images show the capsule less readily because of reduced signal-to-noise ratio. Sometimes, displaced blood vessels around a space-occupying hepatic mass mimic the appearance of a capsule.
Received
Hepatic
Pictorial
Rings in subacute hematomas are mediated by iron-contaming products of hemoglobin degradation. An outer ring has very low signal intensity on all pulse sequences, is sometimes incomplete, and has been attributed to magnetic field inhomogeneity induced by iron particles, either hemosiderin or ferritin. Inside the dark outer ring is a bright ring of very
1 1 , 1989.
Presented in part at the annual meeting of the American Roentgen Ray Society, New Orleans, May 1989. This work was supported in part by funds from the American Cancer Fellowship from the Radiological Society of North America (S. Saini). 1 2 3
Society,
JFRA-163
and PDT-326
(D. D. Stark),
and a Research
and Education
Department of Radiology, Harvard Medical School and the Massachusetts General Hospital, Boston, MA 021 14. Address reprint requests to P. F. Hahn. Present address: Institut f#{252}r klinische Radiologie, Westf#{228}lische Wilhelms-Universit#{228}t,D4000 MUnster, Federal Republic of Germany. Present address: Magnetic Resonance Imaging Unit, Hospital Universitario, Monterrey, Nuevo Leon 64460, Mexico.
AJR 154:287-290,
February
1990 0361 -803X/90/1
542-0287
© American
Roentgen
Ray Society
Fund
Downloaded from www.ajronline.org by 201.164.233.125 on 10/23/15 from IP address 201.164.233.125. Copyright ARRS. For personal use only; all rights reserved
288
HAHN
ET AL.
AJR:154,
February
1990
Sz:irMs
I
“
i.aI4e
;I.”
.
Fig. 1.-Hepatocellular carcinoma. Ring in this case is formed by a capsule. A, SE 260/14 MR image obtained at 0.6 T shows capsule as thin peripheral ring (arrows) signal intensity between tumor and surrounding liver. Fatty degeneration in tumor shortens increases contrast with capsule. B, T2-weighted MR image (SE 2350/120) shows capsule less distinctiy.
of low Ti and
Fig. 3.-Metastasis with peritumoral halo of increased water in liver tissue around lesion. A, T2-weighted SE 2350/120 MR image shows halo (arrow) of lengthened T2 adjacent to tumor. B, Ti-weighted MR image fails to show zone of increased water around lesion.
short Ti best seen on Ti-weighted images. This ring mdicates the paramagnetic effect of methemoglobin at the periphery of the clot. Hemorrhages associated with hepatic neoplasms rarely exhibit the symmetry found in traumatic hematomas (Fig. 6). ,
Inflammatory
Cysts
Hydatid liver cysts [4] have a cyst wall that resembles the capsule in primary liver tumors. However, contiguous with the very long Ti cyst contents, the capsule is poorly demonstrated on Ti -weighted images. In contrast, T2-weighted images show the capsule as a rim of low signal intensity between the high signal intensity of the fluid cyst and the intermediate signal intensity of surrounding liver (Fig. 7).
Fig. 2.-Encapsulated hepatocellular adenoma. Low-signal-intensity capsule (arrows) on 0.6-T SE 260/14 MR image is indistinguishable from capsule of hepatomas. Decreased density of mobile protons in fibrous tissue accounts for low signal intensity. (Reprinted with permission from Rummeny et al [1].)
Fig. 4.-Metastases shown on MR image at 1.5 T, SE 2000/80. Ring of viable tumor surrounding central necrosis (arrows) gives target appearance. Note peritumoral halo.
Daughter cysts are demarcated from the parent cyst by a wall of low signal intensity. Amebic liver abscesses [5] respond to antibiotic treatment by developing four concentric zones. Both Ti - and T2weighted images are required to show all of them (Fig. 8). The central liquefied abscess is surrounded by inflamed granulation tissue and a band of collagen. A narrow zone of edematous liver forms the perimeter. Edema is not visible on Ti -weighted images. T2-weighted images show the central necrosis and granulation inside and edema outside as hyperintense zones separated by the hypointense collagenous wall. Serial T2-weighted images show progressive resolution of the peripheral hepatic edema after treatment. Peripheral edema may be present around untreated abscesses, but usually it is not symmetric radially; the other ring features are absent or irregular and indistinct prior to therapy.
Downloaded from www.ajronline.org by 201.164.233.125 on 10/23/15 from IP address 201.164.233.125. Copyright ARRS. For personal use only; all rights reserved
Fig. 5.-Unusual cavernous hemangioma, with central cyst. A, SE 260/14 MR image obtained at 0.6 1 shows ring of low-signal-intensity hemangioma tissue (arrow) around long Ti cyst. B, On SE 2000/32 MR image, central zone is visible. C, With more 12-weighting, SE 2000/64, lesion appears homogeneous because both cyst and hemangloma have long T2. (Reprinted with permission from Stark and Bradley [3].)
Fig. 6.-Hematoma from small hepatoma imaged at 1.5 T. A, SE 410/17 TI-weighted MR image best shows bright inner ring (large arrows) of methemoglobin and dark outer ring (small arrows) of iron particle deposition. B, SE 2800/80 MR image does not visualize distinctive bright ring against long 12 of clot. (Courtesy of N. 0. Whltley, Baltimore, MD.)
A
Fig. 7.-Hydatid cyst imaged at 051. A, T2-weighted SE 2000/60 MR image shows low-signal-intensity wall (arrows) around cyst. B, Ti-weighted SE 500/25 MR image does not show wall because low signal intensity of cyst contents C, CT scan resembles Ti-weighted MR Image and shows wall of daughter cyst only. (Courtesy of L-G. Vici, Caracas, Venezuela.)
B
provides
Insufficient
contrast.
Downloaded from www.ajronline.org by 201.164.233.125 on 10/23/15 from IP address 201.164.233.125. Copyright ARRS. For personal use only; all rights reserved
290
HAHN
ET AL.
AJR:154,
February
1990
Fig. 8.-Treated amebic liver abscess, imaged at 0.351. A, Ti-weighted SE 500/28 MR image shows three of four zones found histologically. Central low-signal-intensity cyst is surrounded concentrically by zone of intermediate-signal-intensity granulation tissue (white arrows) and low-signalintensity abscess wall (black arrows). B, On 12-weighted SE 2000/84 MR image, granulation zone is not separately distinguishable from long T2 cyst contents, both enclosed by wall (black arrows). Lesion is surrounded by edematous liver (white arrows), visible only on 12-weighted image. (Reprinted with permission from Elizondo et al. [5].)
B Fig. 9.-Cavernous hemangioma, showing ringed appearance created by IV injection of contrast material. A, Unenhanced SE 2350/180 MR image at 0.6 I shows typical very long 12 of lesion (H). B, Breath-holding Ti-weighted SE 225/13 MR image 12 mm after IV injection of Gd-DTPA, 0.1 mmol/kg (Beriex Laboratories, Wayne, NJ). As contrast material fills hemangioma, peripheral Ti shortening produces irregular zone resembling a ring (arrows).
Discussion
Not every lesion of the histologic types discussed here will present with ringed architecture. However, both Ti - and T2weighted images should be obtained to detect rings associated with hepatic masses, and both Ti - and T2-weighted images should be analyzed to distinguish among the various lesions that can have rings. A bright ring on Ti -weighted images usually indicates hemorrtiage. Melanoma metastases and fatty degeneration in primary liver tumors can be hypenintense compared with normal liver, as can any lesion in the setting of hepatic iron overload. The coincidence of one of these conditions with central necrosis could produce a hyperintense ring. Therefore, the hypointense ring peripheral to the ring of hypenintensity is an important feature of hematomas.
A bright ring on T2-weighted
images
indicates
an increase
tissue water, seen around both inflammatory cysts and malignant neoplasms. The presence of a capsule distinguishes hepatocellular carcinomas and adenomas from metastases and hemangiomas. The ringed appearances of both treated amebic liver abscesses and hydatid cysts are distinctive. Unfortunately, the in
MR appearance of amebic abscess before treatment is nondiagnostic, and little is known about the spectrum of MR presentations of hydatid disease. When MR images show rings in a liver mass, the architectune on Ti - and T2-weighted images may indicate necrosis, a capsule, walls, methemoglobin, iron particle deposition, or increased hepatic tissue water (congestion or edema). Recognition of these histologic features can lead to a tissuespecific diagnosis. With the advent of IV MR contrast agents, ringed features may be enhanced and the list of ringed conditions extended (Fig. 9). REFERENCES 1 . Rummeny E, Weissleder R, Stark DD, et aI. Primary liver tumors: diagnosis by MR imaging. AJR i989;1 52:63-72 2. Wittenberg J, Stark DD, Forman BH, et al. Differentiation of hepatic
metastases
from hepatic hemangiomas
AJR 1988;151 :79-84 3. Stark DD, Bradley WG, Jr, eds. Magnetic
and cysts by using MR imaging. resonance
imaging.
St. Louis:
Mosby, 1988 4. Hoff FL, Aisen AM, Walden ME, Glazer GM. MR imaging in hydatid disease of the liver. Gastrointest Radiol 1987;12:39-42 5. Elizondo G, Weissleder R, Stark DD, et al. Amebic liver abscess: diagnosis and treatment evaluation with MR imaging. Radiology 1987;165:795-800
