Tohoku
J. Exp. Med., 1990,
T1 and
160, 145-148
T2 Relaxation
Times
on
Gadolinium-Diethylenetriaminepentaacetic
Acid
Images
Enhanced
of Brain
Magnetic
Resonance
Tumors
SUSUMU
YAMADA,
ROKOKUBOTA,
KENJIYAMADA,
SHUICHI
ONO,TAKASHI
HISHINUMA,
TAIJUMATSUZAWA
and SATORU
FUJIWARA*
Department of Radiology and Nuclear Medicine, the
Research Institute for Tuberculosis and Cancer, and
*Department of Neurosurgery, School of Medicine, Tohoku
University, Sendai 980
YAMADA,
S., KUBOTA,R., YAMADA,
K., ONO,S., HISHINUMA,
T., MATSUZAWA,
T. and FUJIWARA,S. TI and T2 Relaxation Times on Gadolinium-Diethylenetriaminepentaacetic Acid Enhanced Magnetic Resonance Images of Brain Tumors.
Tohoku J. Exp. Med., 1990, 160 (2), 145-148
MRI of brain tumors was
performed with CPMG pulse sequence, and T1 and T2 relaxation times were
measured before and after the administration of 0.1 mmol/kg Gd-DTPA. T1 and
T2 became significantly shorter than before with the T1 shortening being about
twice the T2's. Three types of T2 shortening were classified by the difference in
the intra-tumoral transport of Gd-DTPA in the time-course study after the administration. Transportal activity of Gd-DTPA seemed to be reflected by the
physiologic viability of tumor suggested by pre-contrast T2.
magnetic
resonance imaging ; brain tumor ; gadolinium-DTPA ; Carr-Purcell-Meiboom-Gill
pulse sequence ; relaxation time
A paramagnetic contrast agent, gadolinium-diethylenetriaminepentaacetic
acid (Gd-DTPA), has successfully increased the sensitivity for detection of cerebral abnormalities in magnetic resonance (MR) images, and given the characterization of pathologic conditions (Carr et al. 1984; Felix et al. 1985; Graif et al.
1985). According to the clinical use of the contrast agent for the enhancement in
MR images, quantitative analysis is desirable to consider the relation between
Gd-DTPA enhancement and patho-physiologic tissue characteristics (Graif et al.
1985). In this study, the contrast enhancement of brain tumors induced by
Gd-DTPA was quantitatively evaluated by the changes of T1 and T2 relaxation
times.
Received
October
25, 1989;
revision
accepted
145
for publication
January
23, 1990.
146
S. Yamada
et al.
Relaxation
Times
on Enhanced
MRI
147
MATERIALS AND METHODS
Fifteen patients with brain tumors were examined by MR imaging before and after the
administration of Gd-DTPA (Table 1). MR imaging was performed using a 0.14-T resistive
wholebody scanner (BNT1000J : Bruker, Karlsruhe, FRG) with a head coil of 25 cm in
diameter. Carr-Purcell-Meiboom-Gill (CPMG) sequence of eight echoes with an echo
interval (Te) of 34 msec was applied at a short recovery time (Tr, 600 msec) and a long Tr
(1800 msec). The pre-contrast scan with each Tr was performed before i.v., injection of a
0.1 mmol/kg body weight of Gd-DTPA (Japan Schering Co., Ltd., Tokyo). The postcontrast scans were performed 5 min after with short Tr and 15 min after with long Tr in
the same plane of pre-contrast scans. Two data acquisitions were averaged for each scan.
All images were obtained with a 256 x 256 matrix, a two-dimensional Fourier Transform
technique and a 10-mm slice thickness. Regions of interest (ROT) containing 4 pixels were
settled at the tumor lesion whether it showed enhancement or not. T2 at each Tr was
calculated by the methods of Schneiders et al. (1983) and Lee and Riederer (1986), and T1
by the two-point method of Yamada et al. (1989). Ten ROIs' data in each case were
averaged and Student's t-test was used for the statistics.
RESULTS
The contrast enhancement was observed in 12 of the 15 cases. Table 1
showed T1 and T2 measured before and after the administration of Gd-DTPA.
In the positive contrast enhancement group of 12 cases, T 1 and T2 became
significantly shorter than before. The T1 shortening was twice the T2's. In the
time-course study, the subjects were divided into three types of T2 shortening as
follows. Type 1: T2 shortening became much smaller (-51 to -75%) at 15 min
than 5 min after. These cases showed the short pre-contrast T2 (129 to 154 msec).
Type 2 : T2 shortening showed minimum change (+ 15 to -24%).
These cases
showed the middle pre-contrast T2 (165 to 225 msec). Type 3 : T2 shortening
became larger (+47 to +24%) at 15 min after. These cases showed the long
pre-contrast T2 (228 to 277 msec). In the negative contrast enhancement group of
3 cases, T1 and T2 showed no changes before and after, respectively.
No significant differences of T1 and T2 shortenings were observed among the
histologic types of brain tumors.
DISCUSSION
Gd-DTPA has been recognized as an effective contrast agent for MR imaging
in the detection of brain tumor. The mechanism of the enhancement was suggested that the injected Gd-DTPA diffuses to the interstitial tissue of brain tumor
through the destroyed blood-brain barrier, then the accumulated Gd-DTPA in the
tumor tissue shortens the proton T1 and T2 (Carr et al. 1984; Felix et al. 1985;
Graif et al. 1985).
The accuracy of T2 is very high in CPMG pulse sequence (Schneiders et al.
1983; Lee and Riederer 1986; Yamada et al. 1989), and the signal intensity
equation for CPMG pulse sequence proves that T2 is not influenced by the length
of recovery time (Yamada et al. 1989). Therefore, T2 shortening in the timecour-
148
S. Yamada et al.
se study seemed to reflect the dynamics of Gd-DTPA, although T2 was calculated
from the images with different Trs.
Dynamics of Gd-DTPA is affected by tumor vascularity and diffusion volume. Tumors with the larger vascularity than the diffusion volume seem to be
corresponding to Type 1 and vice versa to Type 3. In our time-course study,
Type 1 suggested that the rapid accumulation, diffusion and excretion of GdDTPA were supported by the high tumor viability expressed by the short
pre-contrast T2 which was close to the T2 of normal brain tissue (90 to 120 msec).
On the other hand, Type 3 suggested that the gradual accumulation of Gd-DTPA
for 15 min was observed in the tumor with increased necrotic or cytolytic lesion
expressed by the long pre-contrast T2. Transportal activity of Gd-DTPA seemed
to be reflected by the physiological viability of tumor. This study was not
enough to determine the relation between the histologic type or malignancy of
brain tumor and the Gd-DTPA enhancement.
The quantitative analysis of the enhancement can be satisfactorily observed
by the measurement of T2 in spite of the lower sensitivity than T1. By the
CPMG pulse sequence, T2 can be measured with a high accuracy and the scan
sequences can be recycled with a short interval. The time-course study will
reveal the relation between Gd-DTPA enhancement and pathophysiologic tumor
characteristics.
Further study is encouraged.
Acknowledgments
We thank Dr. K. Kubota for the thoughtful discussionand the Japan ScheringCo.,Ltd.
for generouslysupplying Gd-DTPAfor this study.
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