. Compurmxd .Mc~d;al Imaging and Croplrict Vol. 16. No. 6. pp. 389-395. Printed in the U.S.A. All rights reserved.
1992
0895-61 I l/92 $5.00 + .W Copyright 0 1992 Pergamon Press Ltd.
CONFIGURATIONAL MR CHARACTERISTICS OF METASTATIC BRAIN TUMORS
Shoji Asari,* Tetsuo Makabe, Shinji Katayama, Takahiko Itoh, Shouhei Tsuchida, and Takashi Ohmoto Department
of Neurological Surgery, Okayama University Medical School, 2-5-l Shikata-cho, Okayama-city, 700 Japan (Received 22 May 1992)
Abstract-Magnetic resonance (MR) characteristics of metastatic brain tumors (MBTs) were studied using 15 cases (13 males and 2 females whose ages ranged from 32-78 yr, with the mean age of 57.8 yr; 12 adenocarcinomas, 2 squamous-cell carcinomas, 2 large-cell carcinomas). Nine cases showed hypointensities and five showed isointensities on Tl-weighted images. Six cases showed markedly hypo- or hypointensities, two showed isointensities, and six showed markedly hyper- or hyperintensities on T2-weighted images. One case was markedly hyperintense on both Tl- and Tt-weighted images. The decrease of the signal intensity on the T2-weighted image was the main MR characteristic. A hypointense peritumoral rim was seen in four of the six hyperintense tumors on TZ-weighted images. There was no correlation between the signal intensity and the histological classification. Key Words: Metastatic
brain tumor,
MRl, Signal intensity,
Peritumoral
INTRODUCTION
adenocarcinomas, 2 squamous-cell carcinomas, and 2 large-cell carcinomas. Primary site of the tumor was the lung in nine cases: stomach in three cases; and breast, thyroidea, and an unknown origin in one case each (Table 1). All MRIs were obtained on a 0.5T superconducting magnet (Resona, Yokogawa Medical Systems, Tokyo, Japan) prior to surgery or biopsy. Spin-echo sequences were used to obtain MRIs at 500-600/25 (TR/TE, ms) for a Tl-weighted image, and at 2000/ 100 for a T2-weighted image. A 256 X 256 matrix, 25 cm of field of view, and a slice thickness of 5 or 10 mm were used as parameters in all cases. For the contrast enhancement, gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) was intravenously administered into the antecubital vein at a dose of 0.1 mmol/kg of the body weight. An axial plane view was taken routinely and a coronal view was taken when indicated. Both Tl- and T2-weighted images were taken in all cases and the contrast enhancement was done in 10 cases. In the study of MR findings, the MR signal intensities were divided into five grades: marked hypointensity, hypointensity, isointensity, hyperintensity, and marked hyperintensity (7). The main signal intensity was adopted when the signal intensities were mixed.
There have been an increasing
number of reports concerning the utility of contrast enhancement on magnetic resonance imaging (MRI) in metastatic brain tumors (MBTs) ( l-5). However, holistic MR features of MBTs have not been reported much, probably because of their complexity and histological multiplicity (6,7). In the present paper, the authors present the morphological MR characteristics in 15 patients with MBTs that were histologically confirmed. MATERIALS
AND
METHODS
From March 1988 to September 199 1, we experienced 15 cases with supratentorial MBTs, including 13 males and 2 females ranging in age from 32-78 yr, with the mean age of 57.8 yr. Thirteen cases had a single lesion and two cases had multiple lesions. The largest lesion was studied in the cases with multiple lesions. The location of the tumor included four cases in the parietal lobe and in the occipital lobe each, three in the temporal lobe, and two in the parieto-occipital lobe and in the frontotemporal lobe each (Table 1). Histological diagnosis was confirmed by a craniotomy or a stereotactic biopsy using 2-mm-cup biopsy forceps (Brown-Roberts-Wells System, Radionics Inc., Burlington, MA). Histological examinations disclosed 11
* To whom correspondence
rim
RESULTS
from
should be addressed. 389
The size of the tumors measured on MRIs ranged 1.8-7.0 cm with the mean maximum diameter
390 Table
Computerized
Medical Imaging
1. Summary
of clinical,
November-December/l992,
and Graphics
histological,
and
MR findings
of 15 cases
Volume
with
16, Number
metastatic
Main MR signal intensity Case no.
Age
Sex
1 2 3 4 5 6 7
61 78 43 59 68 61 61
M M M M M F M
Rt. Lt. Lt. Rt. Lt. Lt. Rt.
occipital parietooccipital occipital parietal temporal occipital temporal
8 9 10 11 12
66 76 39 32 43
M M F M M
Lt. Lt. Lt. Lt. Rt.
frontotemporal parietal frontotemporal temporal parietooccipital
13
52
M
Rt. parietal
14
61
M
Rt. parietal
15
67
M
Lt. occipital
N.D. = not done. * Acute intratumoral
Location
Histological
type
Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Squamous-cell carcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Large-cell carcinoma Large-cell carcinoma Squamous-cell carcinoma Adenocarcinoma
Primary site
brain
tumors
Contrast
_ ‘1‘1
T2 Marked Marked Marked HYPE. Iso. Marked HYPO.
Configuration N.D. N.D. N.D. Ring Entire
Marked Marked N.D. Marked Moderate
Entire Ring N.D. Entire Ring
Marked
Ring
HYPE.
Marked
Ring
HYPE.
Moderate
Ring ___
HYPE. HYPE. HYPE. HYPE. Iso. Marked Hypo.
Unknown Stomach Breast Thyroidea Lung
Iso. HYPE. Iso. Iso. HYPE.
HYPE. Hyper. Hyper.
Lung
lso.
Marked
Lung
HYPE.
Lung
HYPE.
hyper.*
Degree
______.__ enhancement ___-.
N.D. N.D. N.D. Moderate Moderate N.D. Moderate
Lung Stomach Lung Lung Stomach Lung Lung
lso. Marked
hyper. hypo. hyper.
6
hyper.*
hyper.
hypo.
N.r). Entire
hemorrhage.
of 3.1 cm. The tumors showed various signal intensities. In 14 cases, except for one case with acute intratumoral hemorrhage, 4 cases were markedly hypo- or hypointense on both Tl- and T2-weighted images, 5 cases were hypointense on T 1-weighted images and hyperor markedly hyperintense on T2-weighted images, 2 cases were isointense on T l-weighted images and markedly hypo- or hypointense on T2-weighted images, 2 cases were isointense on both T l- and T2weighted images, and 1 case was isointense on Tlweighted image and hyperintense on T2-weighted image (Table 1 and Fig. 1). These results show that in contrast to Tl-weighted images, which showed either hypo- or isointensities (Fig. 2). T2-weighted images had a wider distribution ranging from the marked hypoto the marked hyperintensities (Fig. 3). Consequently, it was found that 6 of 14 cases revealed hypo- or marked hypointensities (42.9%) 2 showed isointensities (14.3%) and 6 showed hyper or marked hyperintensities (42.9%) on TZ-weighted images. Various degrees of edema were demonstrated as hyperintense areas on T2-weighted images in all cases. The tumor parenchyma and the surrounding edema were easily differentiated in eight cases showing hypo- or isointensities on T2-weighted images. Out of six cases showing hyperintensity on T2-weighted images, tumors in four cases were clearly distinguished from the surrounding edema because of the presence of a hypointense peritumoral rim (Fig. 4), but the border of the tumor was unclear in remaining two cases without the hypointense peritumoral rim. All tumors with administration of Gd-
DTPA were enhanced more than moderate degree (Table I). Ring-shaped enhancement with a homogeneous signal intensity and similar thickness was demonstrated in six cases (Fig. 5a), and entirely heterogeneous enhancement was seen in four cases (Fig. 5b) (Table 1). The border of the tumor was clear in all of the enhanced cases. When the correlation between MR signal intensity and histological type was studied, 11 cases of adenocarcinomas, except for one hemorrhaged case, showed hypo- or isointensities on Tl-weighted images, but there were wide variations ranging from marked hypointensities to marked hyperintensities on T2weighted images. In the two large-cell carcinomas, one case showed isointensity on T l-weighted image and marked hypointensity on T2-weighted image. and another showed hyperintensities on both Tl- and T2weighted images. The two squamous-cell carcinomas were revealed as hypointense lesions on both Tl- and T2-weighted images. Adenocarcinomas, most frequently seen in this study, varied in signal intensities and there was no correlation between the signal intensity and the histological type. It was too small in number to elucidate this correlation in other histological types. DISCUSSION It is well known that MRI is an important diagnostic tool for detecting the lesions in the central nervous system. In the past, many authors have reported
+ I-
MR characteristics of me&static brain tumors
@O@
T2
/l
Ti
--
+
391
S. ASARI et al.
I ??*
I
.@I0
+
??
I
0
0
-
It
+ +
+I-
Fig. 1. Signal intensities of the metastatic brain tumors. Tl-weighted images show hypo- or isointensities in 14 cases except for 1 case with acute intratumoral hemorrhage. Various degrees of signal intensities ranging from marked hypointensity to marked hyperintensity are shown on T2-weighted images. There is no correlation between = large-cell the signal intensity and the histological type. 0 = adenocarcinoma; @ = squamous-cell carcinoma; carcinoma; * = with fresh hemorrhage; - = marked hypointensity; - - = hypointensity; + = isointensity; + = hyperintensity; ++ = marked hyperintensity.
(4 Fig. 2. Metastatic
lesions are demonstrated
03 as either hypointensity [(a) arrow, Case 71 or isointensity Case 51 on Tl-weighted images.
[(b) arrows,
392
Computerized Medical Imaging and Graphics
November-December/l992,
Volume 16, Number 6
(a)
Fig. 3. On T2-weighted images, metastatic lesions have a variety of signal intensities. 6 out of 14 lesions (42.9%) were markedly hypointense or hypointense [(a) Case 71, 2 (14.3%) were isointense [(b) Case 51, and 6 (42.9%) were hyper- or markedly hyperintense [(c) arrows, Case I]. 8 out of 14 lesions (57. I %) revealed decreases in the signal intensities on T2-weighted images, which seem to be one of the characteristics of MR findings in this disease.
MR characteristics of metastatic brain tumors
Fig. 4. This metastatic tumor (Case I 1) is mainly revealed as a hyperintensity with a hypointense rim (arrows) at its pe-
riphery on TZweighted image. Hyperintense tumor parenchyma is clearly distinguished from the surrounding edema by this hypointense rim. the usefulness of MRI for the diagnosis or follow-up study of MBTs, particularly emphasizing the utility of postcontrast MRI ( l-5). However, there have been only a few reports concerning the MR configurational characteristics, comparison with histological type, and distinguishing MBTs from glioblastoma multiforme (6, 7). Therefore, this study focused on clarifying the characteristics of MR findings in MBTs. In our series, T2-weighted images had a wider distribution of signal intensities ranging from marked hypointensities to marked hyperintensities, in contrast to T 1-weighted images, which were either hypo- dr isointense. It was especially interesting in that eight cases (57.1%) were hypo- or isointense on T2-weighted images. Tsuchiya et al. (7) also reported that 5 out of 12 cases (4 1.7%) showed hypointensities on T2-weighted images. Hinshow et al. (8) described that all of the 12 metastatic adenocarcinomas of the brain produced decreasing signal intensities on T2-weighted images. Generally, since T 1- and T2-relaxation times are prolonged in brain tumors, most tumors are delimited as the hyperintense area on TZweighted images. Because of this, the hypo- or isointensities on T2-weighted images seem to be one of the characteristics of MR findings in MBTs. Therefore, hypo- or isointensities shown on TZweighted images are valuable in the differential diagnosis of other brain tumors, especially for the glio-
S. ASARIef al.
??
393
blastoma multiforme. When there were hypo- or isointensities on T2-weighted images, it was considered that glioblastoma multiforme at least appeared to be negated. In regard to this, 14 cases of glioblastoma multiforme, which we experienced during the same period, were all demonstrated as hyperintense lesions on T2weighted images. The reason why MBTs produced hypointensity on T2-weighted image is still unknown. According to Hinshow et al. (8), the hemosiderin deposits due to intratumoral microhemorrhage is considered as a possible cause for this phenomenon. In addition, the differences between MBT and glioblastoma multiforme in the evolution of MR signal intensity pattern, which occurred after intratumoral hemorrhage (9), may play an important role. Moreover, the differences in the intratumoral environment, such as cyst, necrosis, hemorrhage, abnormal tumor vessels, and/or high-dense area of viable tumor cells between these two histological types, are thought to be some of the possible mechanisms (7). The border between the tumor parenchyma and the surrounding edema is often difficult to be defined in malignant brain tumors on MRI without contrast enhancement. In this study, the hypointense peritumoral rim was noticed in four out of six cases (66.7%) that showed hyperintensities on TZweighted images. This hypointense peritumoral rim is an important finding that delineates the border between the tumor parenchyma and the surrounding edema, and also one of the MR characteristics of MBTs. In our glioblastoma multiforme series, this phenomenon was not identified in all cases. The presence of the hypointense peritumoral rim is probably due to the shortening of T2relaxation time by hemosiderin and the differences in growth patterns between MBT and glioblastoma multiforme (7). Many reports have previously indicated that contrast enhancement is an important technique in the detection of metastatic lesions. In particular, it is valuable for the detection of small lesions. In our 10 cases with contrast enhancement, all lesions were clearly enhanced by the administration of Gd-DTPA. Tumor parenchyma showed a ring-shaped configuration, or an entirely and heterogeneously enhanced lesion, and no nodule-like shape on postcontrast MRIs. This was probably because the tumors in our series were large in size with the mean diameter of 3.1 cm. Generally, it seems that the tumor is nodule-like in shape, with homogeneous enhancement when it is small in size, but as it increases in size, the signal intensity becomes more irregular and complex. Although all adenocarcinomas showed hypo- or isointensities on T 1-weighted images, there was a wide distribution of signal intensities on TZweighted images.
394
Computerized
Medical Imaging and Graphics
November-Decembex/l992,
Volume
16, Number
Fig. 5. Postcontrast T I -weighted images disclose a well-defined ring-shaped lesion with almost [(a) Case
141 and entirely
and
heterogeneously
Squamous-cell and large-cell carcinomas could not be studied because they were few in number. No correlation was found between the signal intensity and the histological classification of MBTs in our study.
SUMMARY The authors studied the MR characteristics of MBTs using 15 cases ( 13 males and 2 females, 32-78 yrs old with the mean age of 57.8 yr) including 12 adenocarcinomas, two squamous-cell carcinomas and two large-cell carcinomas. One case showed marked hyperintensity indicating massive intratumoral hemorrhage on both T 1- and T2-weighted images. Of T lweighted images, nine cases were hypointense and five were isointense. However, on TZweighted images, two cases were markedly hypointense, four were hypointense, two were isointense, three were hyperintense, and three were markedly hyperintense. Eight cases (57.1%) showed decreases in the signal intensities on T2-weighted images, which was one of MR characteristics of MBTs. Brain edema was seen in all of the cases on T2-weighted image. A hypointense peritumoral rim was recognized in four out of six cases (66.7%) with hyperintensities on T2-weighted images. In these four cases, the border between tumor parenchyma and surrounding edema could be clearly-identified by this hypoi.ntense peritumoral rim. The postcontrast MRI was valuable in the diagnosis of MBTs. There was no cor-
enhanced
lesion [(b) Case
the same
6
thickness
71.
relation between the MR signal intensity tological classification.
and the his-
REFERENCES I. Davis. P.C.: Hudgins. P.A.; Peterman, S.B.. et al. Diagnosis of cerebral metastases: Double-dose delayed CT vs. contrast enhanced MR imaging. - - AJNR I2:293; 199 I 2. Hearty, M.E.: Hesselink. J.R.; Press, G.A.. et al. Increased detection of intracranial metastases with intravenous Cd-DTPA. Radiology 165:619: 1987 3. Russel1.E.J.; Geremia, G.K.; Johnson, C.E.. et al. MultIpIe cerebral metastases: Detectabilitv with Cd-DTPA enhanced MR imaging. Radiology 165:609; 1987. 4. Sze, G.; Shin, J.; Krol, G.. et al. lntraparenchymal brain metastases: MR imaging versus contrast-enhanced CT. Radiology 168: 187; 1988. 5. Sze. G.; Milano, E.; Johnson, C.. et al. Detection of brain mctastases: Comparison of contrast-enhanced MR with unenhanced MR and enhanced CT. AJNR I 1:785;1990. 6. Claussen, C.: Laniado. M.; Schorner, W., et al. GadoliniumDTPA in MR imaging ofglioblastomas and intracranial metastases. AJNR 6:669; 1985. 7. Tsuchiya, K.; Makita, K.: Irie. T., et al. MR findings of metastatlc brain tumors. Jpn. J. Clin. Radiol. 34: I37 I ; 1989. 8. Hinshaw. D.B.: Leon. J.M.: Peckham, N.. et al. MR of metastatic adenocarcinoma to the brain. AJNR 9: 1013: 1988 .__ . 9. Atlas, SW.; Grossman, R.I.: Gomorr. J.M. Hemorrhagx Intracranial malignant neoplasms: Spin-echo MR imaging. Radiolog} 164:71: 1987.
About the Author-SHOJI ASAKI, M.D. graduated from Okayama University Medical School in 1970 and completed his residency in neurosurgery in 1976 at the same institution. He passed the 49th Examination of Japanese National Board in 1970. and received Jap-
MR characteristics of metastatic brain tumors anese Board Certification in Neurosurgery in 1977. From 1985 Dr. Asari worked at the Department of Neurological Surgery of Okayama University Medical School, and he is at present Associate Professor. He worked at Mississippi Medical Center from 1987 to 1988, as Visiting Associate Professor of Department of Neurosurgery. He is the author of approximately 2 10 articles on neurosurgery and neuroradiology. He has also authored three books about cerebrovascular diseases and neuroradiology. About the Author-TErsuo MAKABE,M.D. presently works as a resident at the Department of Neurological Surgery of Okayama University Medical School. Dr. Makabe graduated from Tottori University Medical School in 1986. About the Author-SHINJI KATAYAMA, M.D. presently works as a resident at the Department of Neurological Surgery of Okayama University Medical School. He graduated from Okayama University Medical School in 1986. He joined the Department of Neurological Surgery of the same school after graduation. About the Author-TAKAHIKO ITOH,M.D. presently works as a resident at the Department of Neurological Surgery of Okayama Uni-
??
S. ASARIet al.
395
versity Medical School. He graduated from Okayama University Medical School in 1985. He joined the Department of Neurological Surgery of the same school after graduation. About the Author-SHOUHEI TSUCHIDA, M.D. graduated from Okayama University Medical School in 1983 and completed his residency in Neurological Surgery in 1989. He received Japanese Board of Certification in Neurosurgery in 1990. He is presently the chief of Neurosurgery of Kousei Hospital. About the Author-TAKMHI OHMOTO,M.D. graduated from Okayama University Medical School in 1962. He studied Neurosurgery at New York University Medical Center from 1971 to 1972. Dr. Ohmoto was promoted to the first Professor and Chairman of Department of Neurological Surgery of Kagawa Medical College in 1983, and had worked as the Professor and Chairman of Department of Neurological Surgery of Okayama University Medical School since 199 1. His work is manifold, especially in the field of cerebrovascular surgery and neurophysiology.
1992
0895-61 I l/92 $5.00 + .W Copyright 0 1992 Pergamon Press Ltd.
CONFIGURATIONAL MR CHARACTERISTICS OF METASTATIC BRAIN TUMORS
Shoji Asari,* Tetsuo Makabe, Shinji Katayama, Takahiko Itoh, Shouhei Tsuchida, and Takashi Ohmoto Department
of Neurological Surgery, Okayama University Medical School, 2-5-l Shikata-cho, Okayama-city, 700 Japan (Received 22 May 1992)
Abstract-Magnetic resonance (MR) characteristics of metastatic brain tumors (MBTs) were studied using 15 cases (13 males and 2 females whose ages ranged from 32-78 yr, with the mean age of 57.8 yr; 12 adenocarcinomas, 2 squamous-cell carcinomas, 2 large-cell carcinomas). Nine cases showed hypointensities and five showed isointensities on Tl-weighted images. Six cases showed markedly hypo- or hypointensities, two showed isointensities, and six showed markedly hyper- or hyperintensities on T2-weighted images. One case was markedly hyperintense on both Tl- and Tt-weighted images. The decrease of the signal intensity on the T2-weighted image was the main MR characteristic. A hypointense peritumoral rim was seen in four of the six hyperintense tumors on TZ-weighted images. There was no correlation between the signal intensity and the histological classification. Key Words: Metastatic
brain tumor,
MRl, Signal intensity,
Peritumoral
INTRODUCTION
adenocarcinomas, 2 squamous-cell carcinomas, and 2 large-cell carcinomas. Primary site of the tumor was the lung in nine cases: stomach in three cases; and breast, thyroidea, and an unknown origin in one case each (Table 1). All MRIs were obtained on a 0.5T superconducting magnet (Resona, Yokogawa Medical Systems, Tokyo, Japan) prior to surgery or biopsy. Spin-echo sequences were used to obtain MRIs at 500-600/25 (TR/TE, ms) for a Tl-weighted image, and at 2000/ 100 for a T2-weighted image. A 256 X 256 matrix, 25 cm of field of view, and a slice thickness of 5 or 10 mm were used as parameters in all cases. For the contrast enhancement, gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) was intravenously administered into the antecubital vein at a dose of 0.1 mmol/kg of the body weight. An axial plane view was taken routinely and a coronal view was taken when indicated. Both Tl- and T2-weighted images were taken in all cases and the contrast enhancement was done in 10 cases. In the study of MR findings, the MR signal intensities were divided into five grades: marked hypointensity, hypointensity, isointensity, hyperintensity, and marked hyperintensity (7). The main signal intensity was adopted when the signal intensities were mixed.
There have been an increasing
number of reports concerning the utility of contrast enhancement on magnetic resonance imaging (MRI) in metastatic brain tumors (MBTs) ( l-5). However, holistic MR features of MBTs have not been reported much, probably because of their complexity and histological multiplicity (6,7). In the present paper, the authors present the morphological MR characteristics in 15 patients with MBTs that were histologically confirmed. MATERIALS
AND
METHODS
From March 1988 to September 199 1, we experienced 15 cases with supratentorial MBTs, including 13 males and 2 females ranging in age from 32-78 yr, with the mean age of 57.8 yr. Thirteen cases had a single lesion and two cases had multiple lesions. The largest lesion was studied in the cases with multiple lesions. The location of the tumor included four cases in the parietal lobe and in the occipital lobe each, three in the temporal lobe, and two in the parieto-occipital lobe and in the frontotemporal lobe each (Table 1). Histological diagnosis was confirmed by a craniotomy or a stereotactic biopsy using 2-mm-cup biopsy forceps (Brown-Roberts-Wells System, Radionics Inc., Burlington, MA). Histological examinations disclosed 11
* To whom correspondence
rim
RESULTS
from
should be addressed. 389
The size of the tumors measured on MRIs ranged 1.8-7.0 cm with the mean maximum diameter
390 Table
Computerized
Medical Imaging
1. Summary
of clinical,
November-December/l992,
and Graphics
histological,
and
MR findings
of 15 cases
Volume
with
16, Number
metastatic
Main MR signal intensity Case no.
Age
Sex
1 2 3 4 5 6 7
61 78 43 59 68 61 61
M M M M M F M
Rt. Lt. Lt. Rt. Lt. Lt. Rt.
occipital parietooccipital occipital parietal temporal occipital temporal
8 9 10 11 12
66 76 39 32 43
M M F M M
Lt. Lt. Lt. Lt. Rt.
frontotemporal parietal frontotemporal temporal parietooccipital
13
52
M
Rt. parietal
14
61
M
Rt. parietal
15
67
M
Lt. occipital
N.D. = not done. * Acute intratumoral
Location
Histological
type
Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Squamous-cell carcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Adenocarcinoma Large-cell carcinoma Large-cell carcinoma Squamous-cell carcinoma Adenocarcinoma
Primary site
brain
tumors
Contrast
_ ‘1‘1
T2 Marked Marked Marked HYPE. Iso. Marked HYPO.
Configuration N.D. N.D. N.D. Ring Entire
Marked Marked N.D. Marked Moderate
Entire Ring N.D. Entire Ring
Marked
Ring
HYPE.
Marked
Ring
HYPE.
Moderate
Ring ___
HYPE. HYPE. HYPE. HYPE. Iso. Marked Hypo.
Unknown Stomach Breast Thyroidea Lung
Iso. HYPE. Iso. Iso. HYPE.
HYPE. Hyper. Hyper.
Lung
lso.
Marked
Lung
HYPE.
Lung
HYPE.
hyper.*
Degree
______.__ enhancement ___-.
N.D. N.D. N.D. Moderate Moderate N.D. Moderate
Lung Stomach Lung Lung Stomach Lung Lung
lso. Marked
hyper. hypo. hyper.
6
hyper.*
hyper.
hypo.
N.r). Entire
hemorrhage.
of 3.1 cm. The tumors showed various signal intensities. In 14 cases, except for one case with acute intratumoral hemorrhage, 4 cases were markedly hypo- or hypointense on both Tl- and T2-weighted images, 5 cases were hypointense on T 1-weighted images and hyperor markedly hyperintense on T2-weighted images, 2 cases were isointense on T l-weighted images and markedly hypo- or hypointense on T2-weighted images, 2 cases were isointense on both T l- and T2weighted images, and 1 case was isointense on Tlweighted image and hyperintense on T2-weighted image (Table 1 and Fig. 1). These results show that in contrast to Tl-weighted images, which showed either hypo- or isointensities (Fig. 2). T2-weighted images had a wider distribution ranging from the marked hypoto the marked hyperintensities (Fig. 3). Consequently, it was found that 6 of 14 cases revealed hypo- or marked hypointensities (42.9%) 2 showed isointensities (14.3%) and 6 showed hyper or marked hyperintensities (42.9%) on TZ-weighted images. Various degrees of edema were demonstrated as hyperintense areas on T2-weighted images in all cases. The tumor parenchyma and the surrounding edema were easily differentiated in eight cases showing hypo- or isointensities on T2-weighted images. Out of six cases showing hyperintensity on T2-weighted images, tumors in four cases were clearly distinguished from the surrounding edema because of the presence of a hypointense peritumoral rim (Fig. 4), but the border of the tumor was unclear in remaining two cases without the hypointense peritumoral rim. All tumors with administration of Gd-
DTPA were enhanced more than moderate degree (Table I). Ring-shaped enhancement with a homogeneous signal intensity and similar thickness was demonstrated in six cases (Fig. 5a), and entirely heterogeneous enhancement was seen in four cases (Fig. 5b) (Table 1). The border of the tumor was clear in all of the enhanced cases. When the correlation between MR signal intensity and histological type was studied, 11 cases of adenocarcinomas, except for one hemorrhaged case, showed hypo- or isointensities on Tl-weighted images, but there were wide variations ranging from marked hypointensities to marked hyperintensities on T2weighted images. In the two large-cell carcinomas, one case showed isointensity on T l-weighted image and marked hypointensity on T2-weighted image. and another showed hyperintensities on both Tl- and T2weighted images. The two squamous-cell carcinomas were revealed as hypointense lesions on both Tl- and T2-weighted images. Adenocarcinomas, most frequently seen in this study, varied in signal intensities and there was no correlation between the signal intensity and the histological type. It was too small in number to elucidate this correlation in other histological types. DISCUSSION It is well known that MRI is an important diagnostic tool for detecting the lesions in the central nervous system. In the past, many authors have reported
+ I-
MR characteristics of me&static brain tumors
@O@
T2
/l
Ti
--
+
391
S. ASARI et al.
I ??*
I
.@I0
+
??
I
0
0
-
It
+ +
+I-
Fig. 1. Signal intensities of the metastatic brain tumors. Tl-weighted images show hypo- or isointensities in 14 cases except for 1 case with acute intratumoral hemorrhage. Various degrees of signal intensities ranging from marked hypointensity to marked hyperintensity are shown on T2-weighted images. There is no correlation between = large-cell the signal intensity and the histological type. 0 = adenocarcinoma; @ = squamous-cell carcinoma; carcinoma; * = with fresh hemorrhage; - = marked hypointensity; - - = hypointensity; + = isointensity; + = hyperintensity; ++ = marked hyperintensity.
(4 Fig. 2. Metastatic
lesions are demonstrated
03 as either hypointensity [(a) arrow, Case 71 or isointensity Case 51 on Tl-weighted images.
[(b) arrows,
392
Computerized Medical Imaging and Graphics
November-December/l992,
Volume 16, Number 6
(a)
Fig. 3. On T2-weighted images, metastatic lesions have a variety of signal intensities. 6 out of 14 lesions (42.9%) were markedly hypointense or hypointense [(a) Case 71, 2 (14.3%) were isointense [(b) Case 51, and 6 (42.9%) were hyper- or markedly hyperintense [(c) arrows, Case I]. 8 out of 14 lesions (57. I %) revealed decreases in the signal intensities on T2-weighted images, which seem to be one of the characteristics of MR findings in this disease.
MR characteristics of metastatic brain tumors
Fig. 4. This metastatic tumor (Case I 1) is mainly revealed as a hyperintensity with a hypointense rim (arrows) at its pe-
riphery on TZweighted image. Hyperintense tumor parenchyma is clearly distinguished from the surrounding edema by this hypointense rim. the usefulness of MRI for the diagnosis or follow-up study of MBTs, particularly emphasizing the utility of postcontrast MRI ( l-5). However, there have been only a few reports concerning the MR configurational characteristics, comparison with histological type, and distinguishing MBTs from glioblastoma multiforme (6, 7). Therefore, this study focused on clarifying the characteristics of MR findings in MBTs. In our series, T2-weighted images had a wider distribution of signal intensities ranging from marked hypointensities to marked hyperintensities, in contrast to T 1-weighted images, which were either hypo- dr isointense. It was especially interesting in that eight cases (57.1%) were hypo- or isointense on T2-weighted images. Tsuchiya et al. (7) also reported that 5 out of 12 cases (4 1.7%) showed hypointensities on T2-weighted images. Hinshow et al. (8) described that all of the 12 metastatic adenocarcinomas of the brain produced decreasing signal intensities on T2-weighted images. Generally, since T 1- and T2-relaxation times are prolonged in brain tumors, most tumors are delimited as the hyperintense area on TZweighted images. Because of this, the hypo- or isointensities on T2-weighted images seem to be one of the characteristics of MR findings in MBTs. Therefore, hypo- or isointensities shown on TZweighted images are valuable in the differential diagnosis of other brain tumors, especially for the glio-
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blastoma multiforme. When there were hypo- or isointensities on T2-weighted images, it was considered that glioblastoma multiforme at least appeared to be negated. In regard to this, 14 cases of glioblastoma multiforme, which we experienced during the same period, were all demonstrated as hyperintense lesions on T2weighted images. The reason why MBTs produced hypointensity on T2-weighted image is still unknown. According to Hinshow et al. (8), the hemosiderin deposits due to intratumoral microhemorrhage is considered as a possible cause for this phenomenon. In addition, the differences between MBT and glioblastoma multiforme in the evolution of MR signal intensity pattern, which occurred after intratumoral hemorrhage (9), may play an important role. Moreover, the differences in the intratumoral environment, such as cyst, necrosis, hemorrhage, abnormal tumor vessels, and/or high-dense area of viable tumor cells between these two histological types, are thought to be some of the possible mechanisms (7). The border between the tumor parenchyma and the surrounding edema is often difficult to be defined in malignant brain tumors on MRI without contrast enhancement. In this study, the hypointense peritumoral rim was noticed in four out of six cases (66.7%) that showed hyperintensities on TZweighted images. This hypointense peritumoral rim is an important finding that delineates the border between the tumor parenchyma and the surrounding edema, and also one of the MR characteristics of MBTs. In our glioblastoma multiforme series, this phenomenon was not identified in all cases. The presence of the hypointense peritumoral rim is probably due to the shortening of T2relaxation time by hemosiderin and the differences in growth patterns between MBT and glioblastoma multiforme (7). Many reports have previously indicated that contrast enhancement is an important technique in the detection of metastatic lesions. In particular, it is valuable for the detection of small lesions. In our 10 cases with contrast enhancement, all lesions were clearly enhanced by the administration of Gd-DTPA. Tumor parenchyma showed a ring-shaped configuration, or an entirely and heterogeneously enhanced lesion, and no nodule-like shape on postcontrast MRIs. This was probably because the tumors in our series were large in size with the mean diameter of 3.1 cm. Generally, it seems that the tumor is nodule-like in shape, with homogeneous enhancement when it is small in size, but as it increases in size, the signal intensity becomes more irregular and complex. Although all adenocarcinomas showed hypo- or isointensities on T 1-weighted images, there was a wide distribution of signal intensities on TZweighted images.
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Fig. 5. Postcontrast T I -weighted images disclose a well-defined ring-shaped lesion with almost [(a) Case
141 and entirely
and
heterogeneously
Squamous-cell and large-cell carcinomas could not be studied because they were few in number. No correlation was found between the signal intensity and the histological classification of MBTs in our study.
SUMMARY The authors studied the MR characteristics of MBTs using 15 cases ( 13 males and 2 females, 32-78 yrs old with the mean age of 57.8 yr) including 12 adenocarcinomas, two squamous-cell carcinomas and two large-cell carcinomas. One case showed marked hyperintensity indicating massive intratumoral hemorrhage on both T 1- and T2-weighted images. Of T lweighted images, nine cases were hypointense and five were isointense. However, on TZweighted images, two cases were markedly hypointense, four were hypointense, two were isointense, three were hyperintense, and three were markedly hyperintense. Eight cases (57.1%) showed decreases in the signal intensities on T2-weighted images, which was one of MR characteristics of MBTs. Brain edema was seen in all of the cases on T2-weighted image. A hypointense peritumoral rim was recognized in four out of six cases (66.7%) with hyperintensities on T2-weighted images. In these four cases, the border between tumor parenchyma and surrounding edema could be clearly-identified by this hypoi.ntense peritumoral rim. The postcontrast MRI was valuable in the diagnosis of MBTs. There was no cor-
enhanced
lesion [(b) Case
the same
6
thickness
71.
relation between the MR signal intensity tological classification.
and the his-
REFERENCES I. Davis. P.C.: Hudgins. P.A.; Peterman, S.B.. et al. Diagnosis of cerebral metastases: Double-dose delayed CT vs. contrast enhanced MR imaging. - - AJNR I2:293; 199 I 2. Hearty, M.E.: Hesselink. J.R.; Press, G.A.. et al. Increased detection of intracranial metastases with intravenous Cd-DTPA. Radiology 165:619: 1987 3. Russel1.E.J.; Geremia, G.K.; Johnson, C.E.. et al. MultIpIe cerebral metastases: Detectabilitv with Cd-DTPA enhanced MR imaging. Radiology 165:609; 1987. 4. Sze, G.; Shin, J.; Krol, G.. et al. lntraparenchymal brain metastases: MR imaging versus contrast-enhanced CT. Radiology 168: 187; 1988. 5. Sze. G.; Milano, E.; Johnson, C.. et al. Detection of brain mctastases: Comparison of contrast-enhanced MR with unenhanced MR and enhanced CT. AJNR I 1:785;1990. 6. Claussen, C.: Laniado. M.; Schorner, W., et al. GadoliniumDTPA in MR imaging ofglioblastomas and intracranial metastases. AJNR 6:669; 1985. 7. Tsuchiya, K.; Makita, K.: Irie. T., et al. MR findings of metastatlc brain tumors. Jpn. J. Clin. Radiol. 34: I37 I ; 1989. 8. Hinshaw. D.B.: Leon. J.M.: Peckham, N.. et al. MR of metastatic adenocarcinoma to the brain. AJNR 9: 1013: 1988 .__ . 9. Atlas, SW.; Grossman, R.I.: Gomorr. J.M. Hemorrhagx Intracranial malignant neoplasms: Spin-echo MR imaging. Radiolog} 164:71: 1987.
About the Author-SHOJI ASAKI, M.D. graduated from Okayama University Medical School in 1970 and completed his residency in neurosurgery in 1976 at the same institution. He passed the 49th Examination of Japanese National Board in 1970. and received Jap-
MR characteristics of metastatic brain tumors anese Board Certification in Neurosurgery in 1977. From 1985 Dr. Asari worked at the Department of Neurological Surgery of Okayama University Medical School, and he is at present Associate Professor. He worked at Mississippi Medical Center from 1987 to 1988, as Visiting Associate Professor of Department of Neurosurgery. He is the author of approximately 2 10 articles on neurosurgery and neuroradiology. He has also authored three books about cerebrovascular diseases and neuroradiology. About the Author-TErsuo MAKABE,M.D. presently works as a resident at the Department of Neurological Surgery of Okayama University Medical School. Dr. Makabe graduated from Tottori University Medical School in 1986. About the Author-SHINJI KATAYAMA, M.D. presently works as a resident at the Department of Neurological Surgery of Okayama University Medical School. He graduated from Okayama University Medical School in 1986. He joined the Department of Neurological Surgery of the same school after graduation. About the Author-TAKAHIKO ITOH,M.D. presently works as a resident at the Department of Neurological Surgery of Okayama Uni-
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versity Medical School. He graduated from Okayama University Medical School in 1985. He joined the Department of Neurological Surgery of the same school after graduation. About the Author-SHOUHEI TSUCHIDA, M.D. graduated from Okayama University Medical School in 1983 and completed his residency in Neurological Surgery in 1989. He received Japanese Board of Certification in Neurosurgery in 1990. He is presently the chief of Neurosurgery of Kousei Hospital. About the Author-TAKMHI OHMOTO,M.D. graduated from Okayama University Medical School in 1962. He studied Neurosurgery at New York University Medical Center from 1971 to 1972. Dr. Ohmoto was promoted to the first Professor and Chairman of Department of Neurological Surgery of Kagawa Medical College in 1983, and had worked as the Professor and Chairman of Department of Neurological Surgery of Okayama University Medical School since 199 1. His work is manifold, especially in the field of cerebrovascular surgery and neurophysiology.
