Transcript PADRE

Neuroanatomy of Visual Pathway and
Brain stem: Demonstration with Modern
MR Technology
Yukunori Korogi, Shingo Kakeda, Tetsuya Yoneda
Department of Radiology, University of Occupational and Environmental Health,
Japan.
Department of course of Radiological Sciences, Kumamoto University School of
Health Sciences
Contents
1. Optic radiation on conventional MRI
2. Phase-weighted MR imaging
1. Optic radiation and calcarine area
2. Brain stem
3. Contrast-enhanced FIESTA image
1. Optic nerve and suprasellar tumors
Contents
1. Optic radiation on conventional MRI
2. Phase-weighted MR imaging
1. Optic radiation and calcarine area
2. Brain stem
3. Contrast-enhanced FIESTA image
1. Optic nerve and suprasellar tumors
MR signal intensity of
the optic radiation
• 11 brain specimens and MR images from
43 healthy volunteers.
• To determine which layer adjacent to the
lateral ventricle on MRI represents the
optic radiation.
• external sagittal stratum=optic radiation
• internal sagittal stratum
• tapetum
from the outside
Kitajima, Korogi, et al. AJNR 1996;17:1379
Optic radiation: histologic specimens
ESS
ISS
Bodian
ESS: external sagittal stratum
ISS: internal sagittal stratum
KB
Bodian x200
AJNR 1996;17:1379
MR signal intensity of
the optic radiation
measuring the distance from the ventricular wall
related to their lower axonal density?
AJNR 1996;17:1379
MR signal intensity of
the optic radiation
• The hyperintense layer on T2-weighted
images represents the external sagittal
stratum, or optic radiation.
• The signal intensity of the external sagittal
stratum seems to reflect histologic
characteristics of low axonal density.
Kitajima, Korogi, et al. AJNR 1996;17:1379
Signal intensity of tissues on conv MRI still not always understood.
Contents
1. Optic radiation on conventional MRI
2. Phase-weighted MR imaging
1. Optic radiation and calcarine area
2. Brain stem
3. contrast-enhanced FIESTA image
1. Optic nerve and suprasellar tumors
Phase-weighted MR imaging
• SWI is one of existing techniques for phaseweighted MR imaging; with SWI, however,
phase difference is fixed and cannot be selected.
• We have developed new phase-weighted MR
imaging, “Phase Difference Enhanced Imaging
(PADRE*)”, in which phase difference between
objective and surrounding tissue is selected in
order to enhance the contrast of objective tissue.
*Yoneda, et al. Proc. Intl. Soc. Mag. Reson. Med., vol.17 p2764, 2009
PADRE technique
surrounding tissue
phase
phase
object
Source imge
PADRE
By
choosing
appropriate
differences,
wethe
areobject
able to
create
PADRE
selects
the phasephase
difference
between
and
various
contrasts
of and
tissues.
surrounding
tissue,
enhances them selectively.
PADRE Images
 3T MR system (Signa EXCITE 3T; GE Healthcare)
three-dimensional fast spoiled gradient-echo (3D fast SPGR)
sequence
TR=45 msec, TE=/28 msec , imaging time= 12 minutes, 22 cm
field of view, 512 x 512 matrix, and 1.4-mm thick sections.
High spatial resolution
(voxel size of 0.4 x 0.4 x 1.4 mm3)
Delineation of optic radiation
and stria of Gennari
• We tried to delineate the optic radiation and
primary visual cortex (stria of Gennari) with
the high-spatial-resolution PADRE at 3T.
• These structures might have specific phase
differences than others.
Visualization of optic radiation
PADRE
KB stain
Three layers are clearly identified on PADRE.
phase difference caused by myelin content?
Visualization of calcarine area (striated
cortex)
coronal
bright line
PADRE
The stria of Gennari is clearly identified on PADRE as a
continuous black line.
Delineation of optic radiation
and stria of Gennari
• Phase-weighted MRI, or PADRE, offers a
different contrast of tissues than conventional
MRI.
• Phase-weighted MRI can constantly delineate
the stria of Gennari and three layers of optic
radiation.
• Phase differences of these structures seem
caused by the myelin content, at least, in part.
Contents
1. Optic radiation on conventional MRI
2. Phase-weighted MR imaging
1. Optic radiation and calcarine area
2. Brain stem
3. contrast-enhanced FIESTA image
1. Optic nerve and suprasellar tumors
Moriya, et al. Parallel session: Encephalopathies 2
Tuesday, 5 Oct. White hall 2
Brain stem
• Brain stem concentrates structures of vital importance.
• Many structures of the brain stem cannot be delineated
on conventional MRI.
• With DTI, the superior, middle, and inferior cerebellar
peduncles and corticospinal tract can be identified.
However, the medial lemniscus, central tegmental tract,
and medial and dorsal longitudinal fasciculi have not
been defined using DTI.
Brain stem
Normal anatomy and MSA
• Using Phase-weighted MRI (PADRE),
• Visualize the small fiber tracts of the brain
stem.
• Detect the pathological changes in a
multiple system atrophy (MSA).
Normal Anatomic Analysis
6 healthy volunteers
Brain stem anatomy on the PADRE images
was assessed on the basis of anatomic
knowledge.
Normal Anatomic
Analysis:
Midbrain
Marjorie A. England, Jennifer
Wakely: Color Atlas of the
BRAIN & SPINAL CORD
p194
Corticospinal
fibers
Spinothalamic
tract
Medial
lemniscus
PADRE
Normal Anatomic Analysis:
Pons and medulla
Transverse pontine
fibers
Central tegmental tract
Superior
cerebellar
peduncle
PADRE
inferior cerebellar peduncle
PADRE
Medial
longitudinal
fasciculus
Investigation of the 3D configuration
coronal image
sagittal image
Medial
lemniscus
Spinothalamic
tract
c
superior cerebellar
peduncle
medial longitudinal fasciculus
PADRE
vs
SWI, T2WI, SPGR
vs
PADRE
T2WI
SWI
SPGR
Analysis of the patients with MSA
MSA-C (n=3), MSA-P (n=2), spinocerebellar ataxia
(SCA) type 6 (n=2), SCA type 8 (n=1), and cortical
cerebellar atrophy (CCA) (n=1).
Comparison of PADRE images between healthy
volunteers and patients.
PADRE images were evaluated on the basis of the
existing anatomical postmortem data regarding MSA.
Evaluation at the level of the pons
(*)superior cerebellar
peduncles
(←) medial longitudinal
fasciculus
(▼) transverse pontine
*
*
fibers
MSA-C
Pathology of MSA-C
disappearance of the
transverse pontine fibers
in MSA-C
*
Healthy volunteer
*
CCA
Evaluation at the level of medulla
(←) inferior
cerebellar
peduncles
atrophy of inferior
cerebellar peduncle
in MSA-C
MSA-C
Healthy volunteer
Pathology of MSA-C
CCA
Early stage MSA-C
59y. m. Duration of symptoms (10 months)
(←) inferior cerebellar
peduncles
(▼) transverse pontine
fibers
PADRE
PADRE
T2WI
T2WI
absence of so-called hot cross bun sign
Analysis of the patients with MSA
Phase-weighted MRI, or PADRE, can offer a new tract
imaging of the brain stem and may have a potential to
reinforce the clinical utility of MRI in differentiating
MSA from other conditions.
Contents
1. Optic radiation on conventional MRI
2. Phase-weighted MR imaging
1. Optic radiation and calcarine area
2. Brain stem
3. Contrast-enhanced FIESTA image
1. Optic nerve and suprasellar tumors
“Missing” optic nerve in large
suprasellar tumors
• In large suprasellar tumors, a preoperative
understanding of the anatomical relationship between
the anterior optic pathways and tumors is an important
factor in determining surgical approaches.
• Conventional MRI often fails to depict the optic nerves
and tracts because of their marked thinning due to
long-term compression.
“Missing” optic nerve in large
suprasellar tumors
detection with contrast-enhanced FIESTA image
• Fast imaging employing steady-state
acquisition (FIESTA) sequence
– high spatial resolution
– increased contrast as concentration of contrast
agent increases.
• CE FIESTA for the detectability of the
anterior optic pathways in patients with
large suprasellar tumors.
Contrast-enhanced CISS
• vestibular schwannomas
• facial nerve, cochlear nerve, vestibular nerve
compressed or involved by the tumor
Shigematsu, Korogi, et al. Contrast-enhanced CISS MRI of
vestibular schwannomas: Phantom and clinical studies. JCAT
23 : 224, 1999
Both CISS and FIESTA sequences have T2/T1 contrast.
contrast enhancement on CISS
450
400
350
signal intensity
信
号
上
昇
率
300
250
CISS-3DFT
3D-T2-TSE
T2 R
T2-TSE
200
150
100
50
0
-50
-100
1E-2
.1
1
10
(mmol)
Gd
concentration
Gd-DTPA
濃度
Shigematsu, Korogi, et al. JCAT 1999
Vestibular schwannomas
Shigematsu, Korogi, et al. JCAT 1999
Optic nerve in suprasellar tumors:
CE FIESTA
• 28 pts with suprasellar tumor
– pituitary adenoma in 19, meningioma in 7 and others in 3.
• Two radiologists
– visibility of 5 segments of anterior optic pathway
– 5 point quality rating
• Conventional MRI (3 mm-thick coronal T2WI, CE 3D
SPGR) vs CE FIESTA
• MR findings also correlated with surgical findings (12
pts)
Meningioma
CE FIESTA
clearly visible
T2WI
invisible
Pituitary adenoma
CE FIESTA
clearly visible
CE SPGR
invisible
Optic nerve in suprasellar tumors:
CE FIESTA
• Of all 140 segments of the anterior optic
pathway, 22% were invisible with
conventional MRI, while 99% could be
identified with CE FIESTA.
• All preoperative CE FIESTA were compatible
with operative findings.
Optic nerve in suprasellar tumors:
CE FIESTA
• CE FIESTA is useful in determining the
location of the anterior optic pathways in
patients with large suprasellar tumor.
• This information is useful in predicting surgical
anatomy and selecting a proper surgical
approach.
Conclusion
• Modern MR technology offers us
novel method to evaluate fine
brain anatomy, which cannot be
evaluated with conventional
imaging techniques.
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