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From the Departments of Radiology (M.B.S., J.C., D.L., S.W.A.) and
Neurology (W.J.S., S.T.), Mount Sinai School of Medicine, New York, NY.
Methods—Thirty-nine patients with clinically diagnosed acute
subcortical infarction and 17 control subjects were imaged with both
conventional and DW MRI from 7 hours to 4 days (mean, 2.0 days) after
onset of symptoms. All images were read blinded to specific clinical
findings. In all cases, the precise neuroanatomic locations of lesions
were noted. These lesions were subsequently correlated by an
experienced stroke neurologist to determine whether their locations
correlated to the patients' symptoms.
Results—The accuracy of DW MRI for acute subcortical infarction
was 94.6%. In 4 of 39 cases, the acute infarction was not detected on
conventional MRI. In 24 of 39 cases, conventional MRI showed the acute
lesion as well as multiple other subcortical lesions. In each of these
24 cases, the DW MRI showed a single lesion to be acute, and in all 24
cases, that lesion corresponded to the patients' acute symptoms.
Conclusions—DW MRI has very high accuracy for acute subcortical
infarction and can differentiate acute from nonacute lesions. These
data have significant implications in guiding patient management and
patient selection for clinical trials.
Time interval of imaging relative to onset of ictus ranged from 7 hours
to 4 days (mean, 48.1 hours or 2.0 days). Of these 39 patients, 6 were
imaged less than or equal to 12 hours after onset of clinical symptoms,
3 were imaged 12 to 24 hours after symptom onset, 12 were imaged 24 to
48 hours after onset of symptoms, and 18 were imaged 48 to 96 hours
after onset of symptoms.
The DW and FSE MR images were read by an experienced neuroradiologist
blinded to specific clinical findings except for the history of "rule
out acute infarction." Included in the blinded readings as controls
were 17 other patients with nonfocal neurological symptoms who were
also scanned with both FSE and DW MR with the use of the identical
protocol.
Criteria for the diagnosis of acute subcortical infarction on DW MR
included the following: (1) focal high intensity, based on prior
literature2 3 4 5 ; (2) a location in the basal ganglia, deep
and/or subcortical white matter, or brain stem; (3) a location or
configuration not thought to represent normal anisotropy of
diffusion; and (4) a location or configuration not thought to
represent a magnetic susceptibility artifact (ie, typically
seen near interfaces between brain and air-filled paranasal sinuses).
The lesion did not necessarily have to be present on more than one
of the three single-axis DW images to be interpreted as an infarction
(ie, obscuration of stroke-related hyperintensity situated within
normal internal capsule hyperintense signal on one diffusion axis might
be eliminated by changing the direction of diffusion sensitivity,
making these anisotropic effects less problematic). In all
cases, the precise neuroanatomic locations of such lesions were noted.
These lesions were subsequently correlated in consultation with an
experienced stroke neurologist, who had personally examined the
patients before the MRI study, to determine whether the locations of
high intensity on DW MR correlated to all or part of the patients'
symptoms. On FSE images, all focal hyperintense abnormalities in deep
and subcortical neuroanatomic locations were noted.
In 4 of 39 cases, the acute infarction (ie, the hyperintense lesion on
DW MR) was not detected on FSE images. Two of these were imaged in less
than 12 hours after onset of symptoms. In 24 of 39 cases, FSE images
showed the acute lesion as well as multiple other subcortical lesions
that were indistinguishable from each other. In each of these 24 cases,
the DW MR showed a single lesion to be acute, and in all 24 cases, that
lesion corresponded to the patients' acute symptoms
(Figure
In 1 case DW MR demonstrated additional acute lesions that did not
correlate with clinically apparent deficits but were subsequently shown
to be clinically relevant and likely due to an acute ischemic
insult.
Previous studies have noted that DW MRI demonstrates acute infarctions
that are not detectable by conventional T2-weighted
MRI.2 3 4 5 Our data indicate that isolated
symptomatic acute subcortical infarction can be detected
with a very high degree of accuracy and can be readily differentiated
from subacute and chronic infarctions in the basal ganglia and
subcortical white matter with the use of DW MRI (Figure
Our study design did not lend itself to answer potentially important
questions about DW MRI interpretation. For instance, because our
blinded reader viewed all three single-axis DW images as a set, we
cannot test the hypothesis that only a single direction of diffusion
sensitivity may be adequate to diagnose these lesions. Similarly, we
cannot determine how many or what percentage of infarctions were
detectable by using only one or only two directions of diffusion
sensitivity. Moreover, we cannot answer questions about which single
diffusion direction is the most important direction to which this type
of imaging should be sensitive for the highest yield. We also recognize
that we may have increased the yield by presenting the reader with
all three images with diffusion sensitivity at each slice location as a
set, simply because the reader had three chances to detect a lesion.
These limitations and questions represent interesting studies
that should be performed in the future.
Our data also demonstrate that abnormal foci in the subcortical gray
and white matter can be identified on DW MRI in regions that do not
correspond to clinically apparent neurological deficits. It is possible
that these are false-positive findings that do not represent
cerebral lesions, but it is more likely that these are acute
infarctions that fail to produce recognized symptoms ("silent"
infarctions). Indeed, silent infarctions are reportedly present on
CT scans of between 10% and 30% of patients with cerebrovascular
disease and are usually small, subcortical lesions.14 15 It
is therefore not unlikely that the foci of hyperintensity on DW MRI
(ie, restricted diffusion) without clinical correlation do indeed
represent infarctions.
The recent development of thrombolytic and
neuroprotective agents has further raised the significance of accurate
detection of acute infarction to new levels, since the real possibility
of early intervention to limit the extent of damage from the
ischemic event exists. However, since the therapy is not
without significant risk, it is important to distinguish patients who
have evidence of new ischemic damage from those who have
(re)emergence of signs and symptoms from preexisting lesions, perhaps
due to unrelated intercurrent infections or metabolic
derangement. Because it is precisely those patients with small
subcortical infarctions who are most likely to have multiple lesions,
many of which may be silent, DW MRI appears to hold important promise
for aiding the clinician in making distinctions that are difficult on
clinical grounds alone. Since most acute interventional trials are
currently limited to patients who can be treated within 6 hours of
symptom onset, it remains to be demonstrated that our findings can be
extended to that time window. However, previous work suggests that DW
abnormalities appear very shortly after the onset of
ischemia.2 3 4 5
The technique of DW MRI is readily performed in patients who cannot
otherwise cooperate for conventional MRI, since in the echo-planar
implementation image acquisition occurs in subsecond time frames,
making this technique particularly attractive as an option in very ill
patients. Moreover, the accurate diagnosis of acute infarction by such
a rapid imaging method is also appropriate for subjects entering
therapeutic trials, where time is of the essence in patient management
and triage. It is as yet uncertain whether DW MRI offers a method for
distinguishing patients who have reversible (or at least potentially
treatable) lesions from those who do not.
Scott W. Atlas has received grant support and acts as an advisor to General Electric Co Medical Systems.
Received June 9, 1997;
revision received September 11, 1997;
accepted October 7, 1997.
2.
Moseley ME, Kucharczyk J, Mintorovitch J, Cohen
Y, Kurhanewicz J, Derugin N, Asgari H, Norman D. Diffusion-weighted MR
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© 1998 American Heart Association, Inc.
Original Contributions
Diffusion-Weighted MRI in Acute Subcortical Infarction
Abstract
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
Background and Purpose—Conventional
imaging lacks sensitivity and specificity for the detection of early
subcortical cerebral infarction. The purposes of our study were (1) to
determine the accuracy of diffusion-weighted (DW) MRI for early
subcortical infarction and (2) to determine the efficacy of DW MRI for
differentiating acute from nonacute subcortical infarctions when
conventional MR demonstrates multiple infarctions.
Key Words: cerebral infarction • diagnostic imaging • magnetic resonance imaging • stroke, acute
Introduction
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
Subcortical
infarctions constitute approximately 25% of all ischemic
events1 and form an important subgroup of stroke patients.
It is generally recognized that conventional imaging lacks sensitivity
for the detection of very early cerebral infarction. Moreover, in the
case of subcortical infarction specifically, it is often impossible to
distinguish acute from nonacute lesions on conventional spin-echo or
FSE MRI. Both of these issues are important for appropriate patient
management, particularly in the era of acute stroke treatment.
Preliminary studies have suggested that DW MR may have high sensitivity
for early cerebral infarction.2 3 4 5 The purpose of our study
was twofold: (1) to determine the accuracy of DW MR for early
subcortical infarction and (2) to determine the efficacy of DW MR for
differentiating acute from nonacute subcortical infarctions when
conventional MR demonstrates multiple subcortical infarctions.
Subjects and Methods
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
Thirty-nine adult patients with a clinical diagnosis of acute
subcortical infarction were imaged with both conventional FSE and DW MR
with a 1.5-T MR scanner modified with hardware for echo-planar imaging
(GE Signa Horizon Echospeed). All images were obtained during the same
imaging session and at the same slice locations in all cases;
5-mm-thick sections with 2.5-mm interslice gaps and a 24-cm field of
view were used for all scans. Proton density–weighted FSE used TR 2000
ms, effective TE 30 ms, number of excitations 2, 192x256 matrix, echo
train length 4 (acquisition time=2:32); T2-weighted FSE used TR 3600
ms, effective TE 95 ms, 192x256 matrix, echo train length 8, number of
excitations 1 (acquisition time=1:41). Multislice single-shot spin-echo
diffusion echo-planar imaging (
=31 ms, 
=36.6 ms, TR/TE=10 000/99
ms) was performed with diffusion sensitivity b=1000 s/mm.2
The diffusion gradients were applied sequentially in three orthogonal
directions to generate three sets of axial DW MR images. The
acquisition time for DW images equaled 25 seconds. Interpretations were
made with the use of all three sets of DW images.
Results
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
Thirty-seven of the 39 patients with the clinical diagnosis of
acute subcortical infarction had focal areas of high intensity on DW MR
that correlated with all or part of the patients' clinical symptoms.
Of the two patients with acute subcortical infarction and negative DW
MRI, one was imaged within 34 hours and the other within 72 hours of
ictus. In 1 of the 17 control patients, an acute focal subcortical
infarction was identified on DW MRI. Overall, the sensitivity of DW MR
for acute subcortical infarction was 94.9%, specificity was 94.1%,
positive predictive value was 97.4%, and negative predictive value was
88.9%. The accuracy of DW MRI for acute subcortical infarction was
94.6% (Table
).
View this table:
[in a new window]
Table 1. Summary of Results: DW MRI for Acute Subcortical Infarction in
39 Patients ). In these 24 cases, 11 were
imaged within 48 hours and 14 were imaged between 56 and 96 hours.
View larger version (109K):
[in a new window]
Figure 1. Seventy-year-old patient with 72 hours of new left
hemiparesis. A, Axial proton density–weighted MRI. B, Axial
T2-weighted MRI. C, Axial DW MRI (diffusion sensitivity direction
cephalocaudad axis). D, Axial DW MRI (diffusion sensitivity direction
cephalocaudad axis). Note multiple focal lesions in the subcortical
white matter and deep gray matter on proton density (A) and T2-weighted
(B) images. From these images, it is not possible to discern which
lesion, if any, is acute. DW images (C, D) at the same two slice
locations demonstrate a single focus of high intensity in the posterior
limb of the right internal capsule (D), indicating the acute
infarction.
Discussion
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
DW MRI is a technique that is exquisitely sensitive to the net
translational movement of water molecules. When placed into a strong
magnetic field gradient, translational movement of water protons
results in a phase shift that can be detected as relative signal loss
compared with regions of reduced water motion. Preliminary studies
using DW MRI have indicated that early infarction is demonstrated as
regional high signal intensity compared with background
tissue.2 This relative hyperintensity presumably reflects
restriction of tissue water movement in the area of infarction,
although the precise pathophysiological events
underlying the change in water diffusion are unclear. It is thought
that the loss of normal homeostasis and cell membrane function within
ischemic cells leads to increased cell membrane permeability.
The secondary shift of water from the extracellular space, where
diffusion is nearly unrestricted, to the intracellular compartment,
where there is apparently a more restricted environment for water
movement, is postulated by many investigators as the cellular event
correlating to the change on MRI.6 7 8 9 
). (It should be
noted that it is difficult to estimate the actual number of nonstroke
cases likely to be evaluated in the clinical context described in this
study. The actual accuracy and positive and negative predictive values
of a diagnostic test will vary with the prevalence of the
disease in the population studied and may be quite different depending
on the circumstances in which the test is applied. However, the high
sensitivity and specificity demonstrated are stable properties, and the
values reported are likely to be generally applicable.10 )
Regardless of the exact explanation of the cause of the signal
alteration, this important advance in MRI compensates for two major
limitations in brain imaging that had yet to be solved: (1) a lack of
sensitivity for very early cerebral infarction and (2) an inability to
clearly distinguish new from old lesions. We have also demonstrated
that the use of single-axis orthogonal DW MRI, without off-line
postprocessing and without quantitative apparent diffusion coefficient
maps, is highly accurate for these lesions. Extremely high accuracy in
our blinded reader study was noted despite the theoretical problems of
diffusion anisotropy, in which high intensity can be present due to
the inherent anatomic orientation of fiber bundles, as in the
subcortical white matter, relative to the direction of diffusion
sensitivity.2 11 In suspected infarctions in or near the
internal capsule specifically, where diffusion anisotropy is high, it
might even be postulated that separating directional sensitivity to
diffusion could be advantageous. While we concur with the notion
expressed by Ulug et al12 that quantitative apparent
diffusion coefficient maps may be useful in research protocols in which
quantitation may be useful, our data contradict the
contention13 that apparent diffusion coefficient maps,
requiring imaging with multiple diffusion sensitivities and subsequent
image processing, are necessary for clinical stroke imaging.
Conclusion
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
DW MR, without the use of quantitative diffusion coefficient
maps, has very high sensitivity, specificity, and accuracy for acute
subcortical infarction and can differentiate acute from nonacute
lesions. DW MR can also reveal additional "acute lesions" in these
patients, which either represent additional clinically silent
acute infarctions or represent false-positive findings. These
data have significant implications in guiding patient management and
patient selection for clinical trials.
Selected Abbreviations and Acronyms
DW
=
diffusion weighted
FSE
=
fast spin-echo
TE
=
echo time
TR
=
repetition time
Footnotes
Reprint requests to S.W. Atlas, MD, Department of Radiology, Mount Sinai School of Medicine, Box 1234, One Gustave L. Levy Place, New York, NY 10029.
References
Top
Abstract
Introduction
Subjects and Methods
Results
Discussion
Conclusion
References
1.
Boiten J, Lodder J. Lacunar infarcts: pathogenesis
and validity of the clinical syndromes. Stroke. 1991;22:1374–1378.
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P. E. Grant, J. He, E. F. Halpern, O. Wu, P. W. Schaefer, L. H. Schwamm, R. F. Budzik, A. G. Sorensen, W. J. Koroshetz, and R. G. Gonzalez Frequency and Clinical Context of Decreased Apparent Diffusion Coefficient Reversal in the Human Brain Radiology, October 1, 2001; 221(1): 43 - 50. [Abstract] [Full Text] [PDF]
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K. Chu, D.-W. Kang, B.-W. Yoon, and J.-K. Roh Diffusion-Weighted Magnetic Resonance in Cerebral Venous Thrombosis Arch Neurol, October 1, 2001; 58(10): 1569 - 1576. [Abstract] [Full Text] [PDF]
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Recommendations for Clinical Trial Evaluation of Acute Stroke Therapies Stroke, July 1, 2001; 32(7): 1598 - 1606. [Abstract] [Full Text] [PDF]
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M. G. Lansberg, V. N. Thijs, M. W. O'Brien, J. O. Ali, A. J. de Crespigny, D. C. Tong, M. E. Moseley, and G. W. Albers Evolution of Apparent Diffusion Coefficient, Diffusion-weighted, and T2-weighted Signal Intensity of Acute Stroke AJNR Am. J. Neuroradiol., April 1, 2001; 22(4): 637 - 644. [Abstract] [Full Text]
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M. G. Lansberg, M. W. O'Brien, D. C. Tong, M. E. Moseley, and G. W. Albers Evolution of Cerebral Infarct Volume Assessed by Diffusion-Weighted Magnetic Resonance Imaging Arch Neurol, April 1, 2001; 58(4): 613 - 617. [Abstract] [Full Text] [PDF]
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I. Linfante, R. H. Llinas, G. Schlaug, C. Chaves, S. Warach, and L. R. Caplan Diffusion-Weighted Imaging and National Institutes of Health Stroke Scale in the Acute Phase of Posterior-Circulation Stroke Arch Neurol, April 1, 2001; 58(4): 621 - 628. [Abstract] [Full Text] [PDF]
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O. Wu, W. J. Koroshetz, L. Ostergaard, F. S. Buonanno, W. A. Copen, R. G. Gonzalez, G. Rordorf, B. R. Rosen, L. H. Schwamm, R. M. Weisskoff, et al. Predicting Tissue Outcome in Acute Human Cerebral Ischemia Using Combined Diffusion- and Perfusion-Weighted MR Imaging Stroke, April 1, 2001; 32(4): 933 - 942. [Abstract] [Full Text] [PDF]
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A. O. Nusbaum, C. Y. Tang, M. S. Buchsbaum, T. C. Wei, and S. W. Atlas Regional and Global Changes in Cerebral Diffusion with Normal Aging AJNR Am. J. Neuroradiol., January 1, 2001; 22(1): 136 - 142. [Abstract] [Full Text] [PDF]
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E. R. Melhem, R. Itoh, L. Jones, and P. B. Barker Diffusion Tensor MR Imaging of the Brain: Effect of Diffusion Weighting on Trace and Anisotropy Measurements AJNR Am. J. Neuroradiol., November 1, 2000; 21(10): 1813 - 1820. [Abstract] [Full Text] [PDF]
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P. W. Schaefer, P. E. Grant, and R. G. Gonzalez Diffusion-weighted MR Imaging of the Brain Radiology, November 1, 2000; 217(2): 331 - 345. [Abstract] [Full Text]
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S. L. Keir and J. M. Wardlaw Systematic Review of Diffusion and Perfusion Imaging in Acute Ischemic Stroke Stroke, November 1, 2000; 31(11): 2723 - 2731. [Abstract] [Full Text] [PDF]
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M. Augustin, R. Bammer, J. Simbrunner, R. Stollberger, H.-P. Hartung, and F. Fazekas Diffusion-weighted Imaging of Patients with Subacute Cerebral Ischemia: Comparison with Conventional and Contrast-enhanced MR Imaging AJNR Am. J. Neuroradiol., October 1, 2000; 21(9): 1596 - 1602. [Abstract] [Full Text]
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M. G. Lansberg, A. M. Norbash, M. P. Marks, D. C. Tong, M. E. Moseley, and G. W. Albers Advantages of Adding Diffusion-Weighted Magnetic Resonance Imaging to Conventional Magnetic Resonance Imaging for Evaluating Acute Stroke Arch Neurol, September 1, 2000; 57(9): 1311 - 1316. [Abstract] [Full Text] [PDF]
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C. Oppenheim, R. Stanescu, D. Dormont, S. Crozier, B. Marro, Y. Samson, G. Rancurel, and C. Marsault False-negative Diffusion-weighted MR Findings in Acute Ischemic Stroke AJNR Am. J. Neuroradiol., August 1, 2000; 21(8): 1434 - 1440. [Abstract] [Full Text]
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S. W. Atlas, P. DuBois, M. B. Singer, and D. Lu Diffusion Measurements in Intracranial Hematomas: Implications for MR Imaging of Acute Stroke AJNR Am. J. Neuroradiol., July 1, 2000; 21(7): 1190 - 1194. [Abstract] [Full Text] [PDF]
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J. Oliveira-Filho, H. Ay, P. W. Schaefer, F. S. Buonanno, Y. Chang, R. G. Gonzalez, and W. J. Koroshetz Diffusion-Weighted Magnetic Resonance Imaging Identifies the "Clinically Relevant" Small-Penetrator Infarcts Arch Neurol, July 1, 2000; 57(7): 1009 - 1014. [Abstract] [Full Text] [PDF]
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L. J. Lee, C. S. Kidwell, J. Alger, S. Starkman, and J. L. Saver Impact on Stroke Subtype Diagnosis of Early Diffusion-Weighted Magnetic Resonance Imaging and Magnetic Resonance Angiography Stroke, May 1, 2000; 31(5): 1081 - 1089. [Abstract] [Full Text] [PDF]
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J.-K. Roh, D.-W. Kang, S.-H. Lee, B.-W. Yoon, and K.-H. Chang Significance of Acute Multiple Brain Infarction on Diffusion-Weighted Imaging Stroke, March 1, 2000; 31(3): 688 - 694. [Abstract] [Full Text] [PDF]
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K. C. Johnston, A. F. Connors Jr, D. P. Wagner, W. A. Knaus, X.-Q. Wang, and E. C. Haley Jr A Predictive Risk Model for Outcomes of Ischemic Stroke Stroke, February 1, 2000; 31(2): 448 - 455. [Abstract] [Full Text] [PDF]
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S. H. Choi, D. L. Na, C. S. Chung, K. H. Lee, D. G. Na, and J. C. Adair Diffusion-weighted MRI in vascular dementia Neurology, January 11, 2000; 54(1): 83 - 83. [Abstract] [Full Text] [PDF]
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M. Muller, W. Reiche, P. Langenscheidt, J. Ha{beta}feld, and T. Hagen Ischemia after Carotid Endarterectomy: Comparison between Transcranial Doppler Sonography and Diffusion-Weighted MR Imaging AJNR Am. J. Neuroradiol., January 1, 2000; 21(1): 47 - 54. [Abstract] [Full Text] [PDF]
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P. M. Britt, J. E. Heiserman, R. M. Snider, H. A. Shill, C. R. Bird, and R. C. Wallace Incidence of Postangiographic Abnormalities Revealed by Diffusion-Weighted MR Imaging AJNR Am. J. Neuroradiol., January 1, 2000; 21(1): 55 - 59. [Abstract] [Full Text] [PDF]
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H. Ay, J. Oliveira-Filho, F. S. Buonanno, M. Ezzeddine, P. W. Schaefer, G. Rordorf, L. H. Schwamm, R. G. Gonzalez, and W. J. Koroshetz Diffusion-Weighted Imaging Identifies a Subset of Lacunar Infarction Associated With Embolic Source Stroke, December 1, 1999; 30(12): 2644 - 2650. [Abstract] [Full Text] [PDF]
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W. T. C. Yuh, T. Ueda, M. White, M. E. Schuster, and T. Taoka The Need for Objective Assessment of the New Imaging Techniques and Understanding the Expanding Roles of Stroke Imaging AJNR Am. J. Neuroradiol., November 1, 1999; 20(10): 1779 - 1784. [Full Text]
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W. J. Schonewille, S. Tuhrim, M. B. Singer, and S. W. Atlas Diffusion-Weighted MRI in Acute Lacunar Syndromes : A Clinical-Radiological Correlation Study Stroke, October 1, 1999; 30(10): 2066 - 2069. [Abstract] [Full Text] [PDF]
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N. J. Beauchamp Jr, P. B. Barker, P. Y. Wang, and P. C. M. vanZijl Imaging of Acute Cerebral Ischemia Radiology, August 1, 1999; 212(2): 307 - 324. [Abstract] [Full Text]
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J. L. Sunshine, R. W. Tarr, C. F. Lanzieri, D. M. D. Landis, W. R. Selman, and J. S. Lewin Hyperacute Stroke: Ultrafast MR Imaging to Triage Patients prior to Therapy Radiology, August 1, 1999; 212(2): 325 - 332. [Abstract] [Full Text]
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M. Fisher and G. W. Albers Applications of diffusion-perfusion magnetic resonance imaging in acute ischemic stroke Neurology, June 1, 1999; 52(9): 1750 - 1750. [Abstract] [Full Text]
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H. Ay, F. S. Buonanno, G. Rordorf, P. W. Schaefer, L. H. Schwamm, O. Wu, R. G. Gonzalez, K. Yamada, G. A. Sorensen, and W. J. Koroshetz Normal diffusion-weighted MRI during stroke-like deficits Neurology, June 1, 1999; 52(9): 1784 - 1784. [Abstract] [Full Text] [PDF]
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D. K. Jones, D. Lythgoe, M. A. Horsfield, A. Simmons, S. C. R. Williams, and H. S. Markus Characterization of White Matter Damage in Ischemic Leukoaraiosis with Diffusion Tensor MRI Stroke, February 1, 1999; 30(2): 393 - 397. [Abstract] [Full Text] [PDF]
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K. Okada, L.-H. Wu, and S. Kobayashi Diffusion-Weighted MRI in Severe Leukoaraiosis Stroke, February 1, 1999; 30(2): 478 - 479. [Full Text] [PDF]
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K.J. van Everdingen, J. van der Grond, L.J. Kappelle, L.M.P. Ramos, and W.P.T.M. Mali Diffusion-Weighted Magnetic Resonance Imaging in Acute Stroke Stroke, September 1, 1998; 29(9): 1783 - 1790. [Abstract] [Full Text] [PDF]
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