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Diffusion-Tensor MR Imaging and Fiber Tractography: A New Method of Describing Aberrant Fiber Connections in Developmental CNS Anomalies¹

¹ From the Departments of Radiology (S.K.L., D.I.K., J.K., D.J.K.), Pediatrics (H.D.K.), and Neurosurgery (D.S.K.), Yonsei University College of Medicine, 134 Shinchondong, Seodaemungu, Seoul 120-752, Korea; and the Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Md (S.M.). Recipient of a Certificate of Merit award for an education exhibit at the 2003 RSNA Scientific Assembly. Received April 21, 2004; revision requested May 21 and received July 7; accepted July 8. All authors have no financial relationships to disclose. Address correspondence to S.K.L. (e-mail: slee@yumc.yonsei.ac.kr).

View larger version (92K): [in a new window]   Figure 1a.  ROIs for generating FT images of the major white matter fiber tracts. (a) FT image of the corticospinal tract (left) is generated from the fibers connecting two ROIs in the longitudinal pontine fibers and the posterior limb of the internal capsule (right). (b) FT images of the corpus callosum (left and bottom right) are generated from a single ROI at the precise anatomic locations on the sagittal color map (top right). (c) FT image of longitudinal fiber bundles connecting anteroposteriorly (green fibers) (left) is generated from ROIs on coronal color maps (right). The superior longitudinal fasciculus (slf) is connected to the arcuate fasciculus (af); these fiber tracts are generated from a single ROI. Fiber tracts of other longitudinal fibers like the cingulum (c) and inferior longitudinal fasciculus (ilf) are also generated from coronal images. (d) FT image of the middle cerebellar peduncles (left) is generated from single ROIs on the coronal view (right). These fiber tracts form a midline crossing by means of the red transverse pontine fibers (thick arrow), and some extend to cortical connections superiorly (thin arrows). (e) FT images of the superior (yellow) and inferior (blue) cerebellar peduncles (left and bottom right) are generated from single ROIs on axial color maps (top right). RAO = right anterior oblique.

View larger version (87K): [in a new window]   Figure 1b.  ROIs for generating FT images of the major white matter fiber tracts. (a) FT image of the corticospinal tract (left) is generated from the fibers connecting two ROIs in the longitudinal pontine fibers and the posterior limb of the internal capsule (right). (b) FT images of the corpus callosum (left and bottom right) are generated from a single ROI at the precise anatomic locations on the sagittal color map (top right). (c) FT image of longitudinal fiber bundles connecting anteroposteriorly (green fibers) (left) is generated from ROIs on coronal color maps (right). The superior longitudinal fasciculus (slf) is connected to the arcuate fasciculus (af); these fiber tracts are generated from a single ROI. Fiber tracts of other longitudinal fibers like the cingulum (c) and inferior longitudinal fasciculus (ilf) are also generated from coronal images. (d) FT image of the middle cerebellar peduncles (left) is generated from single ROIs on the coronal view (right). These fiber tracts form a midline crossing by means of the red transverse pontine fibers (thick arrow), and some extend to cortical connections superiorly (thin arrows). (e) FT images of the superior (yellow) and inferior (blue) cerebellar peduncles (left and bottom right) are generated from single ROIs on axial color maps (top right). RAO = right anterior oblique.

View larger version (82K): [in a new window]   Figure 1c.  ROIs for generating FT images of the major white matter fiber tracts. (a) FT image of the corticospinal tract (left) is generated from the fibers connecting two ROIs in the longitudinal pontine fibers and the posterior limb of the internal capsule (right). (b) FT images of the corpus callosum (left and bottom right) are generated from a single ROI at the precise anatomic locations on the sagittal color map (top right). (c) FT image of longitudinal fiber bundles connecting anteroposteriorly (green fibers) (left) is generated from ROIs on coronal color maps (right). The superior longitudinal fasciculus (slf) is connected to the arcuate fasciculus (af); these fiber tracts are generated from a single ROI. Fiber tracts of other longitudinal fibers like the cingulum (c) and inferior longitudinal fasciculus (ilf) are also generated from coronal images. (d) FT image of the middle cerebellar peduncles (left) is generated from single ROIs on the coronal view (right). These fiber tracts form a midline crossing by means of the red transverse pontine fibers (thick arrow), and some extend to cortical connections superiorly (thin arrows). (e) FT images of the superior (yellow) and inferior (blue) cerebellar peduncles (left and bottom right) are generated from single ROIs on axial color maps (top right). RAO = right anterior oblique.

View larger version (86K): [in a new window]   Figure 1d.  ROIs for generating FT images of the major white matter fiber tracts. (a) FT image of the corticospinal tract (left) is generated from the fibers connecting two ROIs in the longitudinal pontine fibers and the posterior limb of the internal capsule (right). (b) FT images of the corpus callosum (left and bottom right) are generated from a single ROI at the precise anatomic locations on the sagittal color map (top right). (c) FT image of longitudinal fiber bundles connecting anteroposteriorly (green fibers) (left) is generated from ROIs on coronal color maps (right). The superior longitudinal fasciculus (slf) is connected to the arcuate fasciculus (af); these fiber tracts are generated from a single ROI. Fiber tracts of other longitudinal fibers like the cingulum (c) and inferior longitudinal fasciculus (ilf) are also generated from coronal images. (d) FT image of the middle cerebellar peduncles (left) is generated from single ROIs on the coronal view (right). These fiber tracts form a midline crossing by means of the red transverse pontine fibers (thick arrow), and some extend to cortical connections superiorly (thin arrows). (e) FT images of the superior (yellow) and inferior (blue) cerebellar peduncles (left and bottom right) are generated from single ROIs on axial color maps (top right). RAO = right anterior oblique.

View larger version (69K): [in a new window]   Figure 1e.  ROIs for generating FT images of the major white matter fiber tracts. (a) FT image of the corticospinal tract (left) is generated from the fibers connecting two ROIs in the longitudinal pontine fibers and the posterior limb of the internal capsule (right). (b) FT images of the corpus callosum (left and bottom right) are generated from a single ROI at the precise anatomic locations on the sagittal color map (top right). (c) FT image of longitudinal fiber bundles connecting anteroposteriorly (green fibers) (left) is generated from ROIs on coronal color maps (right). The superior longitudinal fasciculus (slf) is connected to the arcuate fasciculus (af); these fiber tracts are generated from a single ROI. Fiber tracts of other longitudinal fibers like the cingulum (c) and inferior longitudinal fasciculus (ilf) are also generated from coronal images. (d) FT image of the middle cerebellar peduncles (left) is generated from single ROIs on the coronal view (right). These fiber tracts form a midline crossing by means of the red transverse pontine fibers (thick arrow), and some extend to cortical connections superiorly (thin arrows). (e) FT images of the superior (yellow) and inferior (blue) cerebellar peduncles (left and bottom right) are generated from single ROIs on axial color maps (top right). RAO = right anterior oblique.

View larger version (166K): [in a new window]   Figure 2a.  Prenatally diagnosed ACC in a newborn girl. (a) Midline sagittal MR image shows absence of the corpus callosum and cingulate gyrus and a radial configuration of the sulcal markings (arrows). (b) FT image shows a thickened bundle of anteroposteriorly running fibers (green and blue fibers), which is the Probst bundle. Note the normal corticospinal tract (yellow fibers).

View larger version (120K): [in a new window]   Figure 2b.  Prenatally diagnosed ACC in a newborn girl. (a) Midline sagittal MR image shows absence of the corpus callosum and cingulate gyrus and a radial configuration of the sulcal markings (arrows). (b) FT image shows a thickened bundle of anteroposteriorly running fibers (green and blue fibers), which is the Probst bundle. Note the normal corticospinal tract (yellow fibers).

View larger version (169K): [in a new window]   Figure 3a.  Partial ACC in a 9-year-old boy with seizure disorder. (a) Axial inversion-recovery image shows partial ACC with a remaining genu portion (*) and colpocephalic configuration of the lateral ventricles (arrows). (b) FT image shows anteroposteriorly running Probst bundles (green fibers) (arrowheads). These converge into the small remaining genu portion (arrow), which connects fibers from not only the frontal lobe but also from other regions of the brain. Compare this appearance with the normal configuration of the corpus callosum and the midline crossing fibers shown in Figure 1b.

View larger version (115K): [in a new window]   Figure 3b.  Partial ACC in a 9-year-old boy with seizure disorder. (a) Axial inversion-recovery image shows partial ACC with a remaining genu portion (*) and colpocephalic configuration of the lateral ventricles (arrows). (b) FT image shows anteroposteriorly running Probst bundles (green fibers) (arrowheads). These converge into the small remaining genu portion (arrow), which connects fibers from not only the frontal lobe but also from other regions of the brain. Compare this appearance with the normal configuration of the corpus callosum and the midline crossing fibers shown in Figure 1b.

View larger version (122K): [in a new window]   Figure 4a.  Hereditary spastic paraplegia in an 18-year-old woman with a progressive spastic gait disturbance that began at the age of 12 years. (a) Sagittal T1-weighted MR image shows thinning of the genu and anterior body of the corpus callosum (arrows). (b) FT image shows loss of the callosal fibers through the genu and anterior body (arrows), whereas the fibers through the rostrum, splenium, and posterior body are normal. Note that the corticospinal tract is normal (arrowheads) even though the patient has spastic motor dysfunction.

View larger version (104K): [in a new window]   Figure 4b.  Hereditary spastic paraplegia in an 18-year-old woman with a progressive spastic gait disturbance that began at the age of 12 years. (a) Sagittal T1-weighted MR image shows thinning of the genu and anterior body of the corpus callosum (arrows). (b) FT image shows loss of the callosal fibers through the genu and anterior body (arrows), whereas the fibers through the rostrum, splenium, and posterior body are normal. Note that the corticospinal tract is normal (arrowheads) even though the patient has spastic motor dysfunction.

View larger version (118K): [in a new window]   Figure 5a.  Cortical dysplasia in a 10-year-old girl with long-standing intractable seizure disorder. (a) Axial T2-weighted MR image shows slightly increased signal intensity in the white matter of the left temporo-occipital lobe with blurring of corticomedullary differentiation (arrows). (b) Interictal axial single photon emission computed tomographic (SPECT) scan shows decreased perfusion in the abnormal area (arrows). (c) Ictal axial SPECT scan shows increased perfusion in the same area (arrowheads). (d) Axial FT image, generated from an ROI in the posterior part of the corona radiata and the inferior longitudinal fasciculus, shows decreased fiber connections around the subcortex of the affected temporo-occipital lobe (arrowheads) compared with the branching pattern of the normal contralateral occipital cortex.

View larger version (110K): [in a new window]   Figure 5b.  Cortical dysplasia in a 10-year-old girl with long-standing intractable seizure disorder. (a) Axial T2-weighted MR image shows slightly increased signal intensity in the white matter of the left temporo-occipital lobe with blurring of corticomedullary differentiation (arrows). (b) Interictal axial single photon emission computed tomographic (SPECT) scan shows decreased perfusion in the abnormal area (arrows). (c) Ictal axial SPECT scan shows increased perfusion in the same area (arrowheads). (d) Axial FT image, generated from an ROI in the posterior part of the corona radiata and the inferior longitudinal fasciculus, shows decreased fiber connections around the subcortex of the affected temporo-occipital lobe (arrowheads) compared with the branching pattern of the normal contralateral occipital cortex.

View larger version (107K): [in a new window]   Figure 5c.  Cortical dysplasia in a 10-year-old girl with long-standing intractable seizure disorder. (a) Axial T2-weighted MR image shows slightly increased signal intensity in the white matter of the left temporo-occipital lobe with blurring of corticomedullary differentiation (arrows). (b) Interictal axial single photon emission computed tomographic (SPECT) scan shows decreased perfusion in the abnormal area (arrows). (c) Ictal axial SPECT scan shows increased perfusion in the same area (arrowheads). (d) Axial FT image, generated from an ROI in the posterior part of the corona radiata and the inferior longitudinal fasciculus, shows decreased fiber connections around the subcortex of the affected temporo-occipital lobe (arrowheads) compared with the branching pattern of the normal contralateral occipital cortex.

View larger version (108K): [in a new window]   Figure 5d.  Cortical dysplasia in a 10-year-old girl with long-standing intractable seizure disorder. (a) Axial T2-weighted MR image shows slightly increased signal intensity in the white matter of the left temporo-occipital lobe with blurring of corticomedullary differentiation (arrows). (b) Interictal axial single photon emission computed tomographic (SPECT) scan shows decreased perfusion in the abnormal area (arrows). (c) Ictal axial SPECT scan shows increased perfusion in the same area (arrowheads). (d) Axial FT image, generated from an ROI in the posterior part of the corona radiata and the inferior longitudinal fasciculus, shows decreased fiber connections around the subcortex of the affected temporo-occipital lobe (arrowheads) compared with the branching pattern of the normal contralateral occipital cortex.

View larger version (113K): [in a new window]   Figure 6a.  Cortical dysplasia in a 22-year-old woman with motor seizure disorder of the left hand. (a) Axial T2-weighted MR images show a thickened and dysplastic cortex (left) with signal intensity changes in the underlying white matter (right). (b) Axial FA map shows decreased anisotropy in the affected white matter (arrows); the gray matter change could not be adequately evaluated. (c) Axial functional MR images of the brain show that the region activated by movement of the left hand (bottom) is displaced inferiorly and laterally in comparison with the region activated by movement of the normal contralateral side (top). (d) FT image shows a curved course of the corticospinal tract along the inferior margin of the dysplastic white matter, an appearance that matches the findings on the functional MR images.

View larger version (155K): [in a new window]   Figure 6b.  Cortical dysplasia in a 22-year-old woman with motor seizure disorder of the left hand. (a) Axial T2-weighted MR images show a thickened and dysplastic cortex (left) with signal intensity changes in the underlying white matter (right). (b) Axial FA map shows decreased anisotropy in the affected white matter (arrows); the gray matter change could not be adequately evaluated. (c) Axial functional MR images of the brain show that the region activated by movement of the left hand (bottom) is displaced inferiorly and laterally in comparison with the region activated by movement of the normal contralateral side (top). (d) FT image shows a curved course of the corticospinal tract along the inferior margin of the dysplastic white matter, an appearance that matches the findings on the functional MR images.

View larger version (68K): [in a new window]   Figure 6c.  Cortical dysplasia in a 22-year-old woman with motor seizure disorder of the left hand. (a) Axial T2-weighted MR images show a thickened and dysplastic cortex (left) with signal intensity changes in the underlying white matter (right). (b) Axial FA map shows decreased anisotropy in the affected white matter (arrows); the gray matter change could not be adequately evaluated. (c) Axial functional MR images of the brain show that the region activated by movement of the left hand (bottom) is displaced inferiorly and laterally in comparison with the region activated by movement of the normal contralateral side (top). (d) FT image shows a curved course of the corticospinal tract along the inferior margin of the dysplastic white matter, an appearance that matches the findings on the functional MR images.

View larger version (72K): [in a new window]   Figure 6d.  Cortical dysplasia in a 22-year-old woman with motor seizure disorder of the left hand. (a) Axial T2-weighted MR images show a thickened and dysplastic cortex (left) with signal intensity changes in the underlying white matter (right). (b) Axial FA map shows decreased anisotropy in the affected white matter (arrows); the gray matter change could not be adequately evaluated. (c) Axial functional MR images of the brain show that the region activated by movement of the left hand (bottom) is displaced inferiorly and laterally in comparison with the region activated by movement of the normal contralateral side (top). (d) FT image shows a curved course of the corticospinal tract along the inferior margin of the dysplastic white matter, an appearance that matches the findings on the functional MR images.

View larger version (136K): [in a new window]   Figure 7a.  Heterotopia in an 18-month-old girl with delayed development. (a) Axial T2-weighted MR image shows thick band heterotopia, the so-called double cortex. (b) Axial FA map shows that heterotopic gray matter has high anisotropy, a finding suggestive of its radial orientation and of arrested neuronal migration. (c) FT image shows failure of the normal connection between the deep white matter and the cortex and absence of cortico-cortical connections (arrows). cc = corpus callosum, cst = corticospinal tract. (d) FT image obtained in a normal child shows normal subcortical U-fibers (arrows) and fiber connectivity between the deep white matter and the cortex. cc = corpus callosum, cst = corticospinal tract.

View larger version (150K): [in a new window]   Figure 7b.  Heterotopia in an 18-month-old girl with delayed development. (a) Axial T2-weighted MR image shows thick band heterotopia, the so-called double cortex. (b) Axial FA map shows that heterotopic gray matter has high anisotropy, a finding suggestive of its radial orientation and of arrested neuronal migration. (c) FT image shows failure of the normal connection between the deep white matter and the cortex and absence of cortico-cortical connections (arrows). cc = corpus callosum, cst = corticospinal tract. (d) FT image obtained in a normal child shows normal subcortical U-fibers (arrows) and fiber connectivity between the deep white matter and the cortex. cc = corpus callosum, cst = corticospinal tract.

View larger version (86K): [in a new window]   Figure 7c.  Heterotopia in an 18-month-old girl with delayed development. (a) Axial T2-weighted MR image shows thick band heterotopia, the so-called double cortex. (b) Axial FA map shows that heterotopic gray matter has high anisotropy, a finding suggestive of its radial orientation and of arrested neuronal migration. (c) FT image shows failure of the normal connection between the deep white matter and the cortex and absence of cortico-cortical connections (arrows). cc = corpus callosum, cst = corticospinal tract. (d) FT image obtained in a normal child shows normal subcortical U-fibers (arrows) and fiber connectivity between the deep white matter and the cortex. cc = corpus callosum, cst = corticospinal tract.

View larger version (92K): [in a new window]   Figure 7d.  Heterotopia in an 18-month-old girl with delayed development. (a) Axial T2-weighted MR image shows thick band heterotopia, the so-called double cortex. (b) Axial FA map shows that heterotopic gray matter has high anisotropy, a finding suggestive of its radial orientation and of arrested neuronal migration. (c) FT image shows failure of the normal connection between the deep white matter and the cortex and absence of cortico-cortical connections (arrows). cc = corpus callosum, cst = corticospinal tract. (d) FT image obtained in a normal child shows normal subcortical U-fibers (arrows) and fiber connectivity between the deep white matter and the cortex. cc = corpus callosum, cst = corticospinal tract.

View larger version (145K): [in a new window]   Figure 8a.  Cerebral palsy in a 6-year-old boy with spastic quadriplegia and periventricular leukomalacia. (a) Axial T2-weighted MR image shows loss of periventricular white matter and dilatation of the lateral ventricle, findings typical of periventricular leukomalacia. (b) Lateral FT image shows thinning of sensory fiber tracts (sf) and absence of posterior thalamic radiations. All fibers to and from the thalamus were generated from the left thalamus (th) (pink area). The corticospinal tract is normal. (c) Lateral FT image obtained in a normal child shows the fibers connected to the thalamus (th). Note the abundant fiber bundles from the thalamus to the parieto-occipital lobe, posterior thalamic radiations (ptr), and sensory fibers (sf) in comparison with the findings in periventricular leukomalacia seen in b.

View larger version (58K): [in a new window]   Figure 8b.  Cerebral palsy in a 6-year-old boy with spastic quadriplegia and periventricular leukomalacia. (a) Axial T2-weighted MR image shows loss of periventricular white matter and dilatation of the lateral ventricle, findings typical of periventricular leukomalacia. (b) Lateral FT image shows thinning of sensory fiber tracts (sf) and absence of posterior thalamic radiations. All fibers to and from the thalamus were generated from the left thalamus (th) (pink area). The corticospinal tract is normal. (c) Lateral FT image obtained in a normal child shows the fibers connected to the thalamus (th). Note the abundant fiber bundles from the thalamus to the parieto-occipital lobe, posterior thalamic radiations (ptr), and sensory fibers (sf) in comparison with the findings in periventricular leukomalacia seen in b.

View larger version (67K): [in a new window]   Figure 8c.  Cerebral palsy in a 6-year-old boy with spastic quadriplegia and periventricular leukomalacia. (a) Axial T2-weighted MR image shows loss of periventricular white matter and dilatation of the lateral ventricle, findings typical of periventricular leukomalacia. (b) Lateral FT image shows thinning of sensory fiber tracts (sf) and absence of posterior thalamic radiations. All fibers to and from the thalamus were generated from the left thalamus (th) (pink area). The corticospinal tract is normal. (c) Lateral FT image obtained in a normal child shows the fibers connected to the thalamus (th). Note the abundant fiber bundles from the thalamus to the parieto-occipital lobe, posterior thalamic radiations (ptr), and sensory fibers (sf) in comparison with the findings in periventricular leukomalacia seen in b.

View larger version (127K): [in a new window]   Figure 9a.  Cerebral palsy in a 20-month-old girl with spastic hemiplegia. (a) Axial T2-weighted MR image obtained at the level of the basal ganglia shows changes of cerebromalacia in the left internal capsule, thalamus, and putamen. (b) Axial magnified MR image of the mid pons shows no abnormalities. (c) Axial color-coded vector map shows decreased volume of the left corticospinal tract as a faint blue area on the left side of the pons (arrow). (d) Axial color-coded vector map obtained in an age-matched control subject shows a symmetrical configuration of the corticospinal tract (cst) and other major fibers passing through the pons. mcp = middle cerebellar peduncle, ml = medial lemniscus, tpf = transverse pontine fibers. (e) FT image shows volume loss of the left corticospinal tract.

View larger version (138K): [in a new window]   Figure 9b.  Cerebral palsy in a 20-month-old girl with spastic hemiplegia. (a) Axial T2-weighted MR image obtained at the level of the basal ganglia shows changes of cerebromalacia in the left internal capsule, thalamus, and putamen. (b) Axial magnified MR image of the mid pons shows no abnormalities. (c) Axial color-coded vector map shows decreased volume of the left corticospinal tract as a faint blue area on the left side of the pons (arrow). (d) Axial color-coded vector map obtained in an age-matched control subject shows a symmetrical configuration of the corticospinal tract (cst) and other major fibers passing through the pons. mcp = middle cerebellar peduncle, ml = medial lemniscus, tpf = transverse pontine fibers. (e) FT image shows volume loss of the left corticospinal tract.

View larger version (94K): [in a new window]   Figure 9c.  Cerebral palsy in a 20-month-old girl with spastic hemiplegia. (a) Axial T2-weighted MR image obtained at the level of the basal ganglia shows changes of cerebromalacia in the left internal capsule, thalamus, and putamen. (b) Axial magnified MR image of the mid pons shows no abnormalities. (c) Axial color-coded vector map shows decreased volume of the left corticospinal tract as a faint blue area on the left side of the pons (arrow). (d) Axial color-coded vector map obtained in an age-matched control subject shows a symmetrical configuration of the corticospinal tract (cst) and other major fibers passing through the pons. mcp = middle cerebellar peduncle, ml = medial lemniscus, tpf = transverse pontine fibers. (e) FT image shows volume loss of the left corticospinal tract.

View larger version (104K): [in a new window]   Figure 9d.  Cerebral palsy in a 20-month-old girl with spastic hemiplegia. (a) Axial T2-weighted MR image obtained at the level of the basal ganglia shows changes of cerebromalacia in the left internal capsule, thalamus, and putamen. (b) Axial magnified MR image of the mid pons shows no abnormalities. (c) Axial color-coded vector map shows decreased volume of the left corticospinal tract as a faint blue area on the left side of the pons (arrow). (d) Axial color-coded vector map obtained in an age-matched control subject shows a symmetrical configuration of the corticospinal tract (cst) and other major fibers passing through the pons. mcp = middle cerebellar peduncle, ml = medial lemniscus, tpf = transverse pontine fibers. (e) FT image shows volume loss of the left corticospinal tract.

View larger version (43K): [in a new window]   Figure 9e.  Cerebral palsy in a 20-month-old girl with spastic hemiplegia. (a) Axial T2-weighted MR image obtained at the level of the basal ganglia shows changes of cerebromalacia in the left internal capsule, thalamus, and putamen. (b) Axial magnified MR image of the mid pons shows no abnormalities. (c) Axial color-coded vector map shows decreased volume of the left corticospinal tract as a faint blue area on the left side of the pons (arrow). (d) Axial color-coded vector map obtained in an age-matched control subject shows a symmetrical configuration of the corticospinal tract (cst) and other major fibers passing through the pons. mcp = middle cerebellar peduncle, ml = medial lemniscus, tpf = transverse pontine fibers. (e) FT image shows volume loss of the left corticospinal tract.

View larger version (139K): [in a new window]   Figure 10a.  Joubert syndrome in an 18-month-old boy with delayed development and hypotonia. (a) Axial T2-weighted MR image shows a "molar tooth" appearance of the SCP (arrows) and vermian hypoplasia, which are the typical findings of Joubert syndrome. (b) Axial FA (left) and color vector (right) maps show high anisotropy and an anteroposterior direction (green area) of the SCP with thickening (arrowheads). (c) FT image shows an elongated SCP (arrowheads) with a strong connection from the cerebellum to both the sensory and motor cortices (arrow). cst = corticospinal tract. (d) FT image obtained in a normal age-matched control subject shows normal volume of the SCP and normal cortical connections compared with those in Joubert syndrome seen in c. cst = corticospinal tract.

View larger version (80K): [in a new window]   Figure 10b.  Joubert syndrome in an 18-month-old boy with delayed development and hypotonia. (a) Axial T2-weighted MR image shows a "molar tooth" appearance of the SCP (arrows) and vermian hypoplasia, which are the typical findings of Joubert syndrome. (b) Axial FA (left) and color vector (right) maps show high anisotropy and an anteroposterior direction (green area) of the SCP with thickening (arrowheads). (c) FT image shows an elongated SCP (arrowheads) with a strong connection from the cerebellum to both the sensory and motor cortices (arrow). cst = corticospinal tract. (d) FT image obtained in a normal age-matched control subject shows normal volume of the SCP and normal cortical connections compared with those in Joubert syndrome seen in c. cst = corticospinal tract.

View larger version (138K): [in a new window]   Figure 10c.  Joubert syndrome in an 18-month-old boy with delayed development and hypotonia. (a) Axial T2-weighted MR image shows a "molar tooth" appearance of the SCP (arrows) and vermian hypoplasia, which are the typical findings of Joubert syndrome. (b) Axial FA (left) and color vector (right) maps show high anisotropy and an anteroposterior direction (green area) of the SCP with thickening (arrowheads). (c) FT image shows an elongated SCP (arrowheads) with a strong connection from the cerebellum to both the sensory and motor cortices (arrow). cst = corticospinal tract. (d) FT image obtained in a normal age-matched control subject shows normal volume of the SCP and normal cortical connections compared with those in Joubert syndrome seen in c. cst = corticospinal tract.

View larger version (144K): [in a new window]   Figure 10d.  Joubert syndrome in an 18-month-old boy with delayed development and hypotonia. (a) Axial T2-weighted MR image shows a "molar tooth" appearance of the SCP (arrows) and vermian hypoplasia, which are the typical findings of Joubert syndrome. (b) Axial FA (left) and color vector (right) maps show high anisotropy and an anteroposterior direction (green area) of the SCP with thickening (arrowheads). (c) FT image shows an elongated SCP (arrowheads) with a strong connection from the cerebellum to both the sensory and motor cortices (arrow). cst = corticospinal tract. (d) FT image obtained in a normal age-matched control subject shows normal volume of the SCP and normal cortical connections compared with those in Joubert syndrome seen in c. cst = corticospinal tract.

View larger version (39K): [in a new window]   Figure 11.  Effects of different threshold values for termination of fiber tracking. FT images show that lowering the FA threshold and increasing the trajectory angle (right) can generate more fibers and contralateral connections than increasing the FA threshold and lowering the trajectory angle (left). Note the fiber connections to the lateral aspect of the precentral gyrus (arrowheads) and the contralateral connections through the corpus callosum (small arrows) and pons (large arrow).