57INTRACRANIAL LESIONS (1)

DAVID SUTTON

DAVID SUTTON PICTURES

DR. Muhammad Bin Zulfiqar PGR-FCPS III SIMS/SHL

• Fig. 57.1 The Hounsfield CT scale. The full scale on the left extends 2000 units. The expanded scale on the right extends over 200 units and includes all body tissues. Head scans are usually done routinely at a window level (L) of 34-40 and a window (W) covering 0-75.

• Fig. 57.2 Serial slices from below upward in an elderly patient with some degree of atrophy with diagrams to illustrate normal anatomy. (A) T = temporal lobe; CP = cerebellopontine angle; B = brainstem; 4 = fourth ventricle; C = cerebellum. (B) D = dorsum sellae; P = pontine cistern; Ba = basilar artery; TH = temporal horn. (C) SC = suprasellar cistern; H = hippocampus; B = brainstem; V = vermis. (D) Ped = peduncle; I = insula; 3V = third ventricle; CQ = corpora quadrigemina. (E) FH = frontal horn; SP = septum pellucidum; CN = caudate nucleus; T = thalamus; CP = choroid plexus; OH = occipital horn. (F) IHF = interhemispheric fissure; B = body of lateral ventricle. (G) Su = sulci; F = falx.

• Fig. 57.2 Serial slices from below upward in an elderly patient with some degree of atrophy with diagrams to illustrate normal anatomy. (A) T = temporal lobe; CP = cerebellopontine angle; B = brainstem; 4 = fourth ventricle; C = cerebellum. (B) D = dorsum sellae; P = pontine cistern; Ba = basilar artery; TH = temporal horn. (C) SC = suprasellar cistern; H = hippocampus; B = brainstem; V = vermis. (D) Ped = peduncle; I = insula; 3V = third ventricle; CQ = corpora quadrigemina. (E) FH = frontal horn; SP = septum pellucidum; CN = caudate nucleus; T = thalamus; CP = choroid plexus; OH = occipital horn. (F) IHF = interhemispheric fissure; B = body of lateral ventricle. (G) Su = sulci; F = falx.

• Fig. 57.2 Serial slices from below upward in an elderly patient with some degree of atrophy with diagrams to illustrate normal anatomy. (A) T = temporal lobe; CP = cerebellopontine angle; B = brainstem; 4 = fourth ventricle; C = cerebellum. (B) D = dorsum sellae; P = pontine cistern; Ba = basilar artery; TH = temporal horn. (C) SC = suprasellar cistern; H = hippocampus; B = brainstem; V = vermis. (D) Ped = peduncle; I = insula; 3V = third ventricle; CQ = corpora quadrigemina. (E) FH = frontal horn; SP = septum pellucidum; CN = caudate nucleus; T = thalamus; CP = choroid plexus; OH = occipital horn. (F) IHF = interhemispheric fissure; B = body of lateral ventricle. (G) Su = sulci; F = falx.

• Fig. 57.2 Serial slices from below upward in an elderly patient with some degree of atrophy with diagrams to illustrate normal anatomy. (A) T = temporal lobe; CP = cerebellopontine angle; B = brainstem; 4 = fourth ventricle; C = cerebellum. (B) D = dorsum sellae; P = pontine cistern; Ba = basilar artery; TH = temporal horn. (C) SC = suprasellar cistern; H = hippocampus; B = brainstem; V = vermis. (D) Ped = peduncle; I = insula; 3V = third ventricle; CQ = corpora quadrigemina. (E) FH = frontal horn; SP = septum pellucidum; CN = caudate nucleus; T = thalamus; CP = choroid plexus; OH = occipital horn. (F) IHF = interhemispheric fissure; B = body of lateral ventricle. (G) Su = sulci; F = falx.

• Fig. 57.3 Diagram illustrating position of patient for coronal or near coronal sections (A, B), and sagittal or near-sagittal sections (C) at CT.

• Fig. 57.4 MRI axial sections showing normal anatomy. (A) T,-weighted section shows CSF black and clear differentiation between white and grey matter. (B-G) T2-weighted sections in another patient show CSF white and white matter dark while grey matter remains grey. Compare with and relate to diagrams in Fig. 57.2.

• Fig. 57.4 MRI axial sections showing normal anatomy. (A) T,-weighted section shows CSF black and clear differentiation between white and grey matter. (B-G) T2-weighted sections in another patient show CSF white and white matter dark while grey matter remains grey. Compare with and relate to diagrams in Fig. 57.2.

• Fig. 57.4 MRI axial sections showing normal anatomy. (A) T,-weighted section shows CSF black and clear differentiation between white and grey matter. (B-G) T2-weighted sections in another patient show CSF white and white matter dark while grey matter remains grey. Compare with and relate to diagrams in Fig. 57.2.

• Fig. 57.4 MRI axial sections showing normal anatomy. (A) T,-weighted section shows CSF black and clear differentiation between white and grey matter. (B-G) T2-weighted sections in another patient show CSF white and white matter dark while grey matter remains grey. Compare with and relate to diagrams in Fig. 57.2.

• Fig. 57.5 MRI corona) sections from before backward. (A,B) The sella and cavernous sinuses with carotid siphons. The chiasm is seen in the suprasellar cistern. (B,C) Pontine cistern and basilar artery (black). (D,E) Cerebellopontine angle cisterns with high-signal CSF in the internal auditory meatus. The medulla and spinal cord are outlined in (F). The hippocampus is also well shown.

• Fig. 57.5 MRI corona) sections from before backward. (A,B) The sella and cavernous sinuses with carotid siphons. The chiasm is seen in the suprasellar cistern. (B,C) Pontine cistern and basilar artery (black). (D,E) Cerebellopontine angle cisterns with high-signal CSF in the internal auditory meatus. The medulla and spinal cord are outlined in (F). The hippocampus is also well shown.

• Fig. 57.5 MRI corona) sections from before backward. (A,B) The sella and cavernous sinuses with carotid siphons. The chiasm is seen in the suprasellar cistern. (B,C) Pontine cistern and basilar artery (black). (D,E) Cerebellopontine angle cisterns with high-signal CSF in the internal auditory meatus. The medulla and spinal cord are outlined in (F). The hippocampus is also well shown.

• Fig. 57.6 Aqueduct stenosis shown by MRI. Sagittal midline section. (Courtesy of Dr Gordon Thomson.)

• Fig. 57.7 Axial T2 - (A) and sagittal T,- (B) weighted images in a patient with the Dandy-Walker syndrome showing an enlarged posterior fossa with a high tentorium, and a large fluid-filled fourth ventricle-cisterna magna complex in association with vermian hypoplasia.

• Fig. 57.8 (A-D), Dandy-Walker syndrome shown by CT.

• Fig. 57.8 (A-D), Dandy-Walker syndrome shown by CT.

• Fig. 57.9 J oubert's syndrome at the level of the pontomesencephalic junction showing the 'molar tooth appearance' with superior cerebellar peduncles clearly seen on the coronal T,- weighted image (A) due to absence of vermian folia. In this other patient with Joubert's syndrome the superior cerebellar peduncles are typically very horizontally orientated on the sagittal T,-weighted image (B). (C) Axial T2W, view of patient with Joubett's syndrome showing molar tooth appearances.

• Fig. 57.9 J oubert's syndrome at the level of the pontomesencephalic junction showing the 'molar tooth appearance' with superior cerebellar peduncles clearly seen on the coronal T,- weighted image (A) due to absence of vermian folia. In this other patient with Joubert's syndrome the superior cerebellar peduncles are typically very horizontally orientated on the sagittal T,-weighted image (B). (C) Axial T2W, view of patient with Joubett's syndrome showing molar tooth appearances.

• Fig. 57.10 Arachnoid cyst (arrows) involving pineal region and quadrigeminal cistern and compressing back of third ventricle, producing marked hydrocephalus.

• Fig. 57.11 Arachnoid cyst in left anterior temporal (A) and Sylvian (B) region. It expands the overlying skull but produces minimal brain displacement.

• Fig. 57.12 MRI study of left anterior temporal arachnoid cyst, proton density. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.)

• Fig. 57.13 (A) Cavum septi pellucidi: C = corpus callosum; F = fornix; CS = cavum septi pellucidi. (B) Cavum septi pellucidi and cavum Vergae: VI = velum interpositum; CV = cavum Vergae; 3 = third ventricle.

• Fig. 57.14 Cyst of the septum pellucidum arrow in A) continuous (B) with cyst of the cavum Vergae (arrow). (C) Velum interpositum (arrows) containing enhanced internal cerebral veins.

• Fig. 57.14 Cyst of the septum pellucidum arrow in A) continuous (B) with cyst of the cavum Vergae (arrow). (C) Velum interpositum (arrows) containing enhanced internal cerebral veins.

• Fig. 57.15 Axial T 2 - (A) and sagittal T,- (B) weighted images showing a cyst of the velum interpositum which extends into the trigone of the left lateral ventricle.

• Fig. 57.16 (A) Complete agenesis of the corpus callosum shown by midline sagittal MRI section. (B) Partial agenesis of the corpus callosum. (C) CT shows lipoma of the corpus callosum with marginal calcification.

• Fig. 57.16 (A) Complete agenesis of the corpus callosum shown by midline sagittal MRI section. (B) Partial agenesis of the corpus callosum. (C) CT shows lipoma of the corpus callosum with marginal calcification.

• Fig. 57.17 Sagittal (A) and coronal (B) T,-weighted images showing an extensive lipoma of a dysplastic corpus callosum. Low signal within the lipoma on the T 2 axial image (C) is likely to represent calcification. There is enlargement of the posterior horns of the lateral ventricles (colpocephaly).

• Fig. 57.17 Sagittal (A) and coronal (B) T,-weighted images showing an extensive lipoma of a dysplastic corpus callosum. Low signal within the lipoma on the T 2 axial image (C) is likely to represent calcification. There is enlargement of the posterior horns of the lateral ventricles (colpocephaly).

• Fig. 57.18 (A,B) Midline bifrontal lobulated lipoma with marginal calcification. Shown by CT. (C) Hamartoma of the left temporal lobe. Coronal MRI study shows a small rounded lesion mainly of low signal similar to cortex.

• Fig. 57.18 (A,B) Midline bifrontal lobulated lipoma with marginal calcification. Shown by CT. (C) Hamartoma of the left temporal lobe. Coronal MRI study shows a small rounded lesion mainly of low signal similar to cortex.

• Fig. 57.19 Porencephaly (A) T 2 - weighted axial study. (B) T,-weighted coronal study. Large cavity in left hemisphere.

• Fig. 57.20 (A) CT shows minor degree of schizencephaly presenting as lateral slit lined by cortex. Axial T 2 - weighted image (B) of a patient with bilateral schizencephaly. The clefts radiate out from the lateral ventricles to the surface of the hemispheres and are lined by grey matter. The cleft on the right is closed-lipped whereas the one on the left is open-lipped and this is evident on the more superior axial T,-weighted image (C).

• Fig. 57.20 (A) CT shows minor degree of schizencephaly presenting as lateral slit lined by cortex. Axial T 2 - weighted image (B) of a patient with bilateral schizencephaly. The clefts radiate out from the lateral ventricles to the surface of the hemispheres and are lined by grey matter. The cleft on the right is closed-lipped whereas the one on the left is open-lipped and this is evident on the more superior axial T,-weighted image (C).

• Fig. 57.21 (A,B) Semilobar holoprosencephaly.

• Fig. 57.22 (A -C) Hydranencephaly

• Fig. 57.23 Cerebral dysplasia with gross pachygyria and poorly formed sulci.

• Fig. 57.24 3D surface rendering MR images in two different patients showing a malformation of cortical development in frontoparietal region (A) and also in both parasagittal regions (B).

• Fig. 57.25 (A) Multiple anomalies including agenesis of corpus callosum, subependymal heterotopia, subcortical heterotopia and polymicrogyria. (B) Diffuse subependymal heterotopia. (C) Unilateral nodular and subependymal heterotopia (arrow). (D) Band-like heterotopic grey matter (arrows) in a patient with epilepsy. Similar but less obvious lesions on right side. Positron density weighted MRI.

• Fig. 57.25 (A) Multiple anomalies including agenesis of corpus callosum, subependymal heterotopia, subcortical heterotopia and polymicrogyria. (B) Diffuse subependymal heterotopia. (C) Unilateral nodular and subependymal heterotopia (arrow). (D) Band-like heterotopic grey matter (arrows) in a patient with epilepsy. Similar but less obvious lesions on right side. Positron density weighted MRI.

• Fig. 57.27 MRI studies of a patient with tuberous sclerosis shows cortical tubers as: (A) low signal (T,-weighted); (B) high signal (T1 -weighted). Calcification is not specifically identified but appears as low signal in the intraventricular tubers.

• Fig. 57.28 (A) Neurofibromatosis showing absence of sphenoid wing on the right. Reversal negative at wider window for bone detail. (B) Axial MRI (T,-weighted) shows right optic nerve glioma as low-signal rounded mass in a patient with neurofibromatosis.

• Fig. 57.29 (A) Sturge-Weber syndrome. Predominantly occipital cortical calcification with some atrophy. Axial T2-weighted image (B) in a patient with Sturge-Weber syndrome shows atrophy of the left cerebral hemisphere. Cortical T2 low signal in the left occipital region is consistent with calcification. There is also some thickening of the calvarium in the left frontal region. On the postcontrast TI axial image (C) there is marked superficial enhancement in the occipital and temporal regions due to the presence of a pial angioma. There is atrophy of the right cerebellar hemisphere (D)-crossed cerebellar diaschisis.

• Fig. 57.29 (A) Sturge-Weber syndrome. Predominantly occipital cortical calcification with some atrophy. Axial T2-weighted image (B) in a patient with Sturge-Weber syndrome shows atrophy of the left cerebral hemisphere. Cortical T2 low signal in the left occipital region is consistent with calcification. There is also some thickening of the calvarium in the left frontal region. On the postcontrast TI axial image (C) there is marked superficial enhancement in the occipital and temporal regions due to the presence of a pial angioma. There is atrophy of the right cerebellar hemisphere (D)-crossed cerebellar diaschisis.

• Fig. 57.30 A vascular mass is shown in the left cerebellar hemisphere in a patient with Von Hippel-Lindau syndrome. The mass shows marked enhancement on the coronal postcontrast image (A) and has a dense vascular blush on the lateral vertebral angiogram (B) with evidence of early venous shunting. Two small enhancing superficial spinal haemangioblastomas are also present in the cervical and upper thoracic region on the T, postcontrast sagittal image (C).

• Fig. 57.30 A vascular mass is shown in the left cerebellar hemisphere in a patient with Von Hippel-Lindau syndrome. The mass shows marked enhancement on the coronal postcontrast image (A) and has a dense vascular blush on the lateral vertebral angiogram (B) with evidence of early venous shunting. Two small enhancing superficial spinal haemangioblastomas are also present in the cervical and upper thoracic region on the T, postcontrast sagittal image (C).

• Fig. 57.31 Axial T2 -weighted image (A) in a patient with a juvenile pilocytic astrocytoma of the right cerebellar hemisphere showing a large cystic component, a little peritumoural vasogenic oedema and hydrocephalus due to obstruction of the fourth ventricle. The T,-weighted coronal postcontrast image (B) shows a superior enhancing mural nodule and minor peripheral enhancement of the cyst wall.

• Fig. 57.32 Cerebellar astrocytoma. (A) Large nodular calcification in a right hemisphere tumour. (B) Large cystic tumour with only fair marginal enhancement. (C) Near midline tumour with irregular marginal enhancement.

• Fig. 57.32 Cerebellar astrocytoma. (A) Large nodular calcification in a right hemisphere tumour. (B) Large cystic tumour with only fair marginal enhancement. (C) Near midline tumour with irregular marginal enhancement.

• Fig. 57.33 MRI studies of cystic juvenile astrocytoma. (A) T,-weighted: tumour and cyst are of different low signals. (B) T2 -weighted: tumour and cyst given uniform high signal.

• Fig. 57.34 Axial T,-weighted MRI (A) showing enlargement of the cranial portions of both optic nerves and the chiasm in keeping with an optic glioma. On the postcontrast T,-weighted coronal images (B,C) there is some enhancement of the tumour.

• Fig. 57.34 Axial T,-weighted MRI (A) showing enlargement of the cranial portions of both optic nerves and the chiasm in keeping with an optic glioma. On the postcontrast T,-weighted coronal images (B,C) there is some enhancement of the tumour.

• Fig. 57.35 These sagittal T,-postcontrast images show a large enhancing sellar/suprasellar chiasmal and hypothalamic mass (A,B), which extends posteriorly along the optic tract, consistent with an optic glioma.

• Fig. 57.36 (A) Coronal MRI section through suprasellar cistern and sella shows chiasm swollen mainly on left side (arrow). The infundibulum is also seen. (B) Postgadolinium the tumour enhances, mainly on the left. (C) Left parasagittal section through the swollen chiasm (arrow).

• Fig. 57.36 (A) Coronal MRI section through suprasellar cistern and sella shows chiasm swollen mainly on left side (arrow). The infundibulum is also seen. (B) Postgadolinium the tumour enhances, mainly on the left. (C) Left parasagittal section through the swollen chiasm (arrow).

• Fig. 57.37 Pontine glioma. (A) Axial T2 i mage through the posterior fossa shows an expanded pons with increased signal, with flattening of the fourth ventricle and pontine cistern. (B) This case shows similar changes to A, with slight marginal enhancement after contrast medium. (C) Sagittal T, view shows an expanded pons and medulla compressing the pontine cistern and displacing aqueduct and fourth ventricle backwards.

• Fig. 57.37 Pontine glioma. (A) Axial T2 i mage through the posterior fossa shows an expanded pons with increased signal, with flattening of the fourth ventricle and pontine cistern. (B) This case shows similar changes to A, with slight marginal enhancement after contrast medium. (C) Sagittal T, view shows an expanded pons and medulla compressing the pontine cistern and displacing aqueduct and fourth ventricle backwards.

• Fig. 57.38 A large complex mass in the left cerebral hemisphere shown on this postcontrast CT (A) and coronal T,-weighted MR image (B) was proven to be a pleomorphic xanthoastrocytoma. It has a large cystic component and the peripheral lobulated solid component shows marked enhancement. Some focal resorption of the overlying skull vault is shown on the coronal MR image.

• Fig. 57.39 Axial MRI study (T,-weighted) shows tumour enhancement after IV gadolinium, resembling enhanced CT study. Mass effect and herniation under the falx are well shown. Glioblastoma multiforme.

• Fig. 57.40 Axial unenhanced CT (A) showing a large complex bifrontal partially cystic haemorrhagic tumour proven to be a glioblastoma. The T 2 signal characteristics are complex (B) and the coronal T, unenhanced image (C) shows large T, hyperintense components due to the presence of methaemoglobin. There is no significant vasogenic oedema despite tumour size but there is resultant obstructive hydrocephalus with early transependymal oedema around the occipital horns.

• Fig. 57.40 Axial unenhanced CT (A) showing a large complex bifrontal partially cystic haemorrhagic tumour proven to be a glioblastoma. The T 2 signal characteristics are complex (B) and the coronal T, unenhanced image (C) shows large T, hyperintense components due to the presence of methaemoglobin. There is no significant vasogenic oedema despite tumour size but there is resultant obstructive hydrocephalus with early transependymal oedema around the occipital horns.

• Fig. 57.41 Axial CTs pre- (A) and post- (B) contrast showing a slightly hyperdense mass precontrast involving the splenium of the corpus callosum and which shows marked enhancement. On the T 2- weighted axial image (C) the large amount of vasogenic oedema is clearly shown and there is some mass effect on the posterior aspects of the lateral ventricles. Although this mass was a glioblastoma the radiological differential would include primary central nervous system lymphoma.

• Fig. 57.41 Axial CTs pre- (A) and post- (B) contrast showing a slightly hyperdense mass precontrast involving the splenium of the corpus callosum and which shows marked enhancement. On the T 2- weighted axial image (C) the large amount of vasogenic oedema is clearly shown and there is some mass effect on the posterior aspects of the lateral ventricles. Although this mass was a glioblastoma the radiological differential would include primary central nervous system lymphoma.

• Fig. 57.42 A heterogeneous mass proven to be a glioblastoma is shown in the left cerebral hemisphere on the T 2 - weighted axial image (A) associated with mass effect and vasogenic oedema. The axial T, postcontrast image (B) shows marked enhancement of the tumour but also evidence of subependymal enhancement, thus spread.

• Fig. 57.43 Axial T2 (A) and T, postcontrast (B) images showing a large left frontal non-enhancing tumour involving cortex and white matter which was proven to be an oligodendroglioma. There is only minimal associated mass effect.

• Fig. 57.44 A large avidly enhancing ependymoma is shown on the sagittal T, postcontrast image (A) occupying the lower part of the fourth ventricle, compressing the medulla and extending through the foramen of Magendie into the upper cervical canal. The axial T 2 image (B) shows that the mass is hyperintense and also extends out through the lateral recesses into the cerebellopontine angles, particularly on the right.

• Fig. 57.45 T2 -weighted MRI study of tumour protruding into left lateral ventricle. The tumour is of mixed but mainly low signal, suggesting multilocular cysts. Ependymoma.

• Fig. 57.48 Axial T2 -weighted image (A,B) showing a lobulated vascular mass within the third ventricle which shows avid uniform enhancement on the coronal postcontrast T,-weighted image and is consistent with a choroid plexus papilloma. The lateral ventricles are markedly dilated due to obstructive hydrocephalus. (C) CT shows a rounded mass of increased attenuation with a low-density centre occupying the fourth ventricle. (D) After contrast medium, a slightly higher section shows strong uniform enhancement.

• Fig. 57.48 Axial T2 -weighted image (A,B) showing a lobulated vascular mass within the third ventricle which shows avid uniform enhancement on the coronal postcontrast T,-weighted image and is consistent with a choroid plexus papilloma. The lateral ventricles are markedly dilated due to obstructive hydrocephalus. (C) CT shows a rounded mass of increased attenuation with a low-density centre occupying the fourth ventricle. (D) After contrast medium, a slightly higher section shows strong uniform enhancement.

• Fig. 57.49 Neuronal and mixed neuronal-glial tumours. A poorly defined hyperintense lesion consistent with a DNT is shown in the right temporal lobe on this T2 -weighted image (A). It involves cortex and white matter and the coronal T, unenhanced image (B) shows it to have a medial cystic component. The lateral patchy signal hyperintensity is likely to be calcification. There is no enhancement of this lesion (C).

• Fig. 57.49 Neuronal and mixed neuronal-glial tumours. A poorly defined hyperintense lesion consistent with a DNT is shown in the right temporal lobe on this T2 -weighted image (A). It involves cortex and white matter and the coronal T, unenhanced image (B) shows it to have a medial cystic component. The lateral patchy signal hyperintensity is likely to be calcification. There is no enhancement of this lesion (C).

• Fig. 57.50 Pineal tumours. Axial postcontrast CT (A) showing an enhancing mass centred on the pineal region invaginating into the third ventricle and resulting in obstructive hydrocephalus with transependymal oedema. This was a proven pineoblastoma. On the axial T 2 -weighted MR image (B) the mass is of slightly heterogeneous T2 signal; enhancement is also slightly heterogeneous on the sagittal T, postcontrast image (C).

• Fig. 57.50 Pineal tumours. Axial postcontrast CT (A) showing an enhancing mass centred on the pineal region invaginating into the third ventricle and resulting in obstructive hydrocephalus with transependymal oedema. This was a proven pineoblastoma. On the axial T 2 -weighted MR image (B) the mass is of slightly heterogeneous T2 signal; enhancement is also slightly heterogeneous on the sagittal T, postcontrast image (C).

• Fig. 57.51 Pineal tumour. (A) Isodense mass with calcification indenting back of third ventricle. (B) Enhancement after contrast medium (L30, W80).

• Fig. 57.52 (A,B) Pineal tumour. Large enhancing and partly calcified mass. Heavy calcification is commonest in germ cell tumours.

• Fig. 57.53 Germ cell tumours. A large heterogeneous T 2 signal mass is shown in the pineal region on the T2 -weighted axial image (A) proven to be a pineal region teratoma. The mass comprises both solid and cystic components and there is heterogeneous enhancement after contrast on sagittal T,-weighted image (B) and the mass results in obstructive hydrocephalus.

• Fig. 57.54 Pituitary tumour. Contrast-enhanced CT. Direct coronal section demonstrates suprasellar extension and relationship to internal carotids and anterior cerebral arteries. The cavernous sinuses on either side are slightly denser than the tumor.

• Fig. 57.55 (A) Rounded mass of slightly increased density in the suprasellar cistern. It enhances homogeneously with contrast medium. The sella was enlarged. Pituitary adenoma. (B) Irregular mass in suprasellar cistern which enhances strongly with contrast medium. As the sella was relatively normal it was thought more likely to be a craniopharyngioma than a pituitary adenoma despite absence of calcification. Histology germinoma.

• Fig. 57.56 Sagittal (A) and coronal (B) reformats of pituitary adenoma after enhancement showing asymmetrical suprasellar extension. The sella is enlarged and the cavernous sinuses bulged laterally.

• Fig. 57.56 Sagittal (A) and coronal (B) reformats of pituitary adenoma after enhancement showing asymmetrical suprasellar extension. The sella is enlarged and the cavernous sinuses bulged laterally.

• Fig. 57.56 Sagittal (A) and coronal (B) reformats of pituitary adenoma after enhancement showing asymmetrical suprasellar extension. The sella is enlarged and the cavernous sinuses bulged laterally.

• Fig. 57.57 (A,B) Large pituitary adenoma showing enlargement and erosion of sella with left lateral and retrosellar as well as suprasellar extension. (C,D) Coronal and sagittal reformat defining asymmetrical suprasellar extent.

• Fig. 57.57 (A,B) Large pituitary adenoma showing enlargement and erosion of sella with left lateral and retrosellar as well as suprasellar extension. (C,D) Coronal and sagittal reformat defining asymmetrical suprasellar extent.

• Fig. 57.57 (A,B) Large pituitary adenoma showing enlargement and erosion of sella with left lateral and retrosellar as well as suprasellar extension. (C,D) Coronal and sagittal reformat defining asymmetrical suprasellar extent.

• Fig. 57.58 Reformat of pituitary adenoma. Note cystic area.

• Fig. 57.58 Reformat of pituitary adenoma. Note cystic area.

• Fig. 57.59 Direct coronal scan shows a microadenoma as a hypodense l esion bulging the sellar floor (arrow). There is also upward bulging of the gland and deviation of the infundibulum.

• Fig. 57.60 Pituitary adenomas. (A,B) Two different cases shown by MRI. (A) Sagittal section (T,- weighted). Suprasellar extension as well as downward extension through the sphenoid sinus and backward extension through the dorsum and clivus. (B) Coronal section (T,-weighted). The tumour is displacing the cavernous sinuses laterally. The internal carotids appear black because of flow defects. (C,D) Sagittal sections of large adenoma before and after gadolinium enhancement. The anterior thirdventricle is indented and the chiasm is stretched over the tumour.

• Fig. 57.60 Pituitary adenomas. (A,B) Two different cases shown by MRI. (A) Sagittal section (T,- weighted). Suprasellar extension as well as downward extension through the sphenoid sinus and backward extension through the dorsum and clivus. (B) Coronal section (T,-weighted). The tumour is displacing the cavernous sinuses laterally. The internal carotids appear black because of flow defects. (C,D) Sagittal sections of large adenoma before and after gadolinium enhancement. The anterior thirdventricle is indented and the chiasm is stretched over the tumour.

• Fig. 57.61 Pituitary microadenoma shown by MRI (proton density).

• Fig. 57.62 A large isointense pituitary macroadenoma is shown on the coronal T1 - weighted image (A) expanding the sella with suprasellar extension and compression of the optic chiasm. The left cavernous sinus is clearly involved with inferior displacement of the intracavernous internal carotid artery. On the axial T7 -weighted image (B) the macroadenoma is hyperintense to brain and not only displaces the terminal internal carotid artery anteriorly, but posteriorly also displaces the basilar artery and indents the ventral pons.

• Fig. 57.63 Mixed T 2 low signal is shown in the sellar region on the and who presented acutely with symptoms and signs of pituitary component. Before (A) and after (B) enhancement. apoplexy. On the coronal T -weighted unenhanced image (B) the sell and suprasellar mass is largely isointense but with strands of hyperintensity. The T 2 and T, signal characteristics suggest the presence of deoxyhaemoglobin and methaemoglobin in a subacute haemorrhage within a pituitary macroadenoma.

• Fig. 57.64 Axial CT (A) and T2-weighted MRI (B) showing a largely cystic lobulated suprasellar mass. There is a small focus of calcification posteriorly within the lesion and appearances are those of a craniopharyngioma. The coronal T1 postcontrast image (C) is of another patient with a craniopharyngioma which has both cystic and solid enhancing components.

• Fig. 57.64 Axial CT (A) and T2-weighted MRI (B) showing a largely cystic lobulated suprasellar mass. There is a small focus of calcification posteriorly within the lesion and appearances are those of a craniopharyngioma. The coronal T1 postcontrast image (C) is of another patient with a craniopharyngioma which has both cystic and solid enhancing components.

• Fig. 57.65 Craniopharyngioma. Cystic tumour with solid enhancing component. Before (A) and after (B) enhancement.

• Fig. 57.66 Cystic suprasellar mass with enhancing capsule. Craniopharyngioma. Some Rathke's cleft cysts can produce a similar appearance. Before (A) and after (B) enhancement.

• Fig. 57.67 Craniopharyngioma. Sagittal midline MRI (T,-weighted) shows high-signal suprasellar mass due to cystic tumour. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.)

• Fig. 57.68 Bilateral complex intrinsic masses are shown in the cerebral hemispheres in a patient with known AIDS. On biopsy these were proven to be primary central nervous system lymphoma. There is a large amount of vasogenic oedema on the T2 -weighted image (A) associated with the right frontal mass and there is extension across the corpus callosum. The coronal T, unenhanced image (B) shows faint T, high signal in the right frontal mass consistent with methaemoglobin. Postcontrast (C) the right frontal lesion shows thick irregular ring enhancement. Subependymal enhancement around the anterior aspects of the frontal horns is also evident, a characteristic feature of cerebral lymphoma.

• Fig. 57.68 Bilateral complex intrinsic masses are shown in the cerebral hemispheres in a patient with known AIDS. On biopsy these were proven to be primary central nervous system lymphoma. There is a large amount of vasogenic oedema on the T2 -weighted image (A) associated with the right frontal mass and there is extension across the corpus callosum. The coronal T, unenhanced image (B) shows faint T, high signal in the right frontal mass consistent with methaemoglobin. Postcontrast (C) the right frontal lesion shows thick irregular ring enhancement. Subependymal enhancement around the anterior aspects of the frontal horns is also evident, a characteristic feature of cerebral lymphoma.

• Fig. 57.69 Lymphoma of brain. (A) CT before contrast. (B) After contrast. Isodense tumour with little mass effect enhances strongly with contrast. (C) MRI, T,-weighted, in another patient. Low-density paraventricular mass involves thalamus and extends into third and left lateral ventricles.

• Fig. 57.69 Lymphoma of brain. (A) CT before contrast. (B) After contrast. Isodense tumour with little mass effect enhances strongly with contrast. (C) MRI, T,-weighted, in another patient. Low-density paraventricular mass involves thalamus and extends into third and left lateral ventricles.

• Fig. 57.70 (A) There i s a high-density parasagittal mass with irregular calcification. (B) The tumour enhances strongly with contrast agent. Parasagittal meningioma.

• Fig. 57.71 (A,B) Cavernous sinus petrous apex meningioma. CT after IV contrast medium. The left cavernous sinus is expanded (open arrow) in continuity with a mass at the petrous apex, which extends along the tentorium (arrow) and into the posterior fossa (arrowhead).

• Fig. 57.72 (A) Frontal meningioma. High-density lesion with some calcification. Unusual degree of oedema. (B) Strong enhancement with contrast medium. (C) Reversal print at wide window to show bone involvement ([80 W400) (D) Parietal meningioma. Superficial isodense mass effacing sulci. (E) Strong enhancement after contrast medium outlines the tumour.

• Fig. 57.72 (A) Frontal meningioma. High-density lesion with some calcification. Unusual degree of oedema. (B) Strong enhancement with contrast medium. (C) Reversal print at wide window to show bone involvement ([80 W400) (D) Parietal meningioma. Superficial isodense mass effacing sulci. (E) Strong enhancement after contrast medium outlines the tumour.

• Fig. 57.72 (A) Frontal meningioma. High-density lesion with some calcification. Unusual degree of oedema. (B) Strong enhancement with contrast medium. (C) Reversal print at wide window to show bone involvement ([80 W400) (D) Parietal meningioma. Superficial isodense mass effacing sulci. (E) Strong enhancement after contrast medium outlines the tumour.

• Fig. 57.73 (A) Strongly enhancing parasagittal falx meningioma. No adjacent oedema but brain compressed and sulci effaced. Coronal (B) and midline (C) sagittal reformats show attachment to falx but no growth across the midline.

• Fig. 57.73 (A) Strongly enhancing parasagittal falx meningioma. No adjacent oedema but brain compressed and sulci effaced. Coronal (B) and midline (C) sagittal reformats show attachment to falx but no growth across the midline.

• Fig. 57.74 Olfactory groove meningioma. Midline sagittal (A) and coronal (B) reformats after contrast medium showing extent of tumour and bony hyperostosis

• Fig. 57.75 Meningioma of territorial apex before (A) and after (B) enhancement.

• Fig. 57.76 Meningioma of the planum sphenoidale. Sagittal (A) and coronal (B) reformats of contrast-enhanced CT. The tumour is contiguous with the enhancing pituitary gland and extends forward along the planum (black arrow). There is blistering of the sphenoidal sinus.

• Fig. 57.76 Meningioma of the planum sphenoidale. Sagittal (A) and coronal (B) reformats of contrast-enhanced CT. The tumour is contiguous with the enhancing pituitary gland and extends forward along the planum (black arrow). There is blistering of the sphenoidal sinus.

Fig. 57.77 (A) Coronal MRI section (T 1 -weighted) shows uniformly low signal of a large parasagittal meningioma. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.) (B) Sagittal MRI study (T,-weighted). A small parasagittal meningioma shows strong uniform enhancement with gadolinium. (C) Coronal MRI, T,-weighted, shows low signal from large meningioma, broadly based on dura and with lower signal rim at brain-meningioma interface. (D) Axial view of same large tumour, T2 -weighted, shows inhomogeneous high signal.represent direct tumour extension, is seen in approximately 70°% o

• Fig. 57.77 (A) Coronal MRI section (T 1 -weighted) shows uniformly low signal of a large parasagittal meningioma. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.) (B) Sagittal MRI study (T,-weighted). A small parasagittal meningioma shows strong uniform enhancement with gadolinium. (C) Coronal MRI, T,-weighted, shows low signal from large meningioma, broadly based on dura and with lower signal rim at brain-meningioma interface. (D) Axial view of same large tumour, T2 -weighted, shows inhomogeneous high signal.represent direct tumour extension, is seen in approximately 70°% o

Fig. 57.77 (A) Coronal MRI section (T 1 -weighted) shows uniformly low signal of a large parasagittal meningioma. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.) (B) Sagittal MRI study (T,-weighted). A small parasagittal meningioma shows strong uniform enhancement with gadolinium. (C) Coronal MRI, T,-weighted, shows low signal from large meningioma, broadly based on dura and with lower signal rim at brain-meningioma interface. (D) Axial view of same large tumour, T2 -weighted, shows inhomogeneous high signal.represent direct tumour extension, is seen in approximately 70°% o

• Fig. 57.78 Selective external carotid angiogram showing meningeal vessels supplying a frontal meningioma (arterial DSA study).

• Fig. 57.79 A large mixed cystic and slid extra-axial mass is shown in the right parietal region on the T2-weighted axial image (A) with marked mass effect on the ipsilateral lateral ventricle. The postcontrast T, coronal (B) image shows the lesion is durally based and shows some heterogeneous enhancement; this was proven to be a haemangiopericytoma.

Fig. 57.80 (A) Haemangioblastoma cyst with enhancing mural nodule (arrow) in left cerebellar hemisphere. (B) Vertebral angiogram also shows the nodule (thick arrow) and a vessel stretched around the cyst.

• Fig. 57.80 (A) Haemangioblastoma cyst with enhancing mural nodule (arrow) in left cerebellar hemisphere. (B) Vertebral angiogram also shows the nodule (thick arrow) and a vessel stretched around the cyst.

• Fig. 57.81 Coronal MRI (T,-weighted). A large haemangioblastoma cyst is well shown. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.)

• Fig. 57.82 Vertebral angiography demonstrates two large vascular haemangioblastomas and several smaller nodules (arrows).

• Fig. 57.83 Axial T2 -weighted high-resolution image (A) showing a rounded right acoustic neuroma isointense with brain straddling the porous acousticus. The internal auditory canal is consequently slightly enlarged. The axial T 1 -weighted postcontrast image in another patient (B) shows an enhancing left acoustic neuroma with mild mass effect on the pons and extending into and filling the left internal auditory canal.

57.84 (A) A small acoustic tumour in the left cerebellopontine angle is demonstrated after contrast enhancement. The dark bands across the pons are artefacts from the dense petrous bones. (B) Imaging at bone window shows bony erosion around the IAM.

• Fig. 57.85 Fifth nerve tumour with marked enhancement after contrast medium. The tumour at the petrous apex extends into both the middle and posterior fossae (L36, W80).

• Fig. 57.86 Corona) T,-weighted postcontrast image (A) showing a lobulated ring-enhancing mass in the region of the geniculate ganglion of the left facial nerve. The dedicated coronal CT (B) acquired on a bone algorithm shows associated bone destruction by the soft-tissue tumour with some involvement of the cochlea

• Fig. 57.87 A lobulated enhancing mass is shown on these T, axial images. It involves the right cavernous sinus and extends posteriorly with marked mass effect on the pons (A). More inferiorly it extends towards the skull base and the region of the foraman ovale (B). This was a neuroma of trigeminal nerve.

• Fig. 57.88 (A) CT at bone window demonstrates erosion of skull base around right jugular foramen. (B) Enhanced MRI shows strongly enhancing tumour extending into posterior fossa. (C) Large glomus jugulare tumour at the skull base and a concomitant carotid body tumour at the carotid bifurcation are both shown by carotid angiography.

• Fig. 57.88 (A) CT at bone window demonstrates erosion of skull base around right jugular foramen. (B) Enhanced MRI shows strongly enhancing tumour extending into posterior fossa. (C) Large glomus jugulare tumour at the skull base and a concomitant carotid body tumour at the carotid bifurcation are both shown by carotid angiography.

• Fig. 57.89 Chordoma of skull base. (A) CT at brain window. Bony density mass protrudes back from the clivus. (B) CT at bone window (slightly lower section) confirms osteochondromatous nature.

• Fig. 57.90 Chordoma. Calcified mass growing backward and upward from the clivus. It is displacing the brainstem and extending up above the sella.

• Fig. 57.91 Chordoma. (A) Extensive infiltrative destruction of the skull base. (B) Enhancing tumour mass extends up into the posterior and middle fossa on the right side involving the right clivus and sella.

• Fig. 57.92 Chordoma. MRI (T 1 -weighted). (A) Sagittal midline section. (B) Axial section. The tumour arising from the clivus is isointense with brain and protrudes backward, deforming the brainstem. It also protrudes forward into the nasopharynx.

• Fig. 57.93 A large heterogeneous T2 signal eccentric suprasellar chondrosarcoma (A) displaces the terminal internal carotid arteries. (B) On the postcontras coronal T,-weighted image the mass involves the clivus and shows heterogeneous enhancement. The axial CT (C) shows that the mass is partially calcified.

• Fig. 57.93 A large heterogeneous T2 signal eccentric suprasellar chondrosarcoma (A) displaces the terminal internal carotid arteries. (B) On the postcontras coronal T,-weighted image the mass involves the clivus and shows heterogeneous enhancement. The axial CT (C) shows that the mass is partially calcified.

• Fig. 57.94 Sagittal T, unenhanced (A) and postcontrast (B) images showing an expansile enhancing chordoma involving the clivus and dens with compression of the craniocervical junction and a large extraosseous soft-tissue component extending into the nasopharynx, ethmoids and prevertebral space.

• Fig. 57.95 Metastases. Three separate lesions, all isodense and enhancing strongly with contrast medium. Oedema around the larger secondaries (L40, W60). Before (A) and after (B) enhancement.

• Fig. 57.96 (A,B) Metastasis. Small isodense enhancing tumour with marked oedema (L36, W80).

• Fig. 57.98 Metastases. (A) Multiple adjacent ring shadows with low density centres. (B) Mainly ring enhancement after contrast.

• Fig. 57.99 Metastases. (A) Coronal MRI (T,-weighted). Symmetrical deposits in the occipital lobes. High signal within the deposits probably due to haemorrhage. Surrounding oedema also shown as high signal. (B) Sagittal MRI (T,-weighted). Frontal lobe adjacent deposits.

• Fig. 57.100 Axial T,-weighted postcontrast image (A) showing bilateral diffuse nodular dural thickening and enhancement in a patient with metastatic breast carcinoma. A small area of underlying cortical signal abnormality is present in the right frontal lobe on the T2 -weighted axial image (B).

• Fig. 57.101 Axial (A) and coronal (B) T1 -weighted postcontrast images in a patient with meningeal leukaemic infiltration. There is meningeal enhancement and thickening around the brainstem and temporal lobes with thickened enhancing 5th nerves and 7th/8th nerve complexes bilaterally.

• Fig. 57.102 Axial T2 - (A) and T1 -weighted postcontrast images (B) show a large lobulated epidermoid in the posterior fossa filling and expanding the fourth ventricle and causing marked displacement of the brainstem. The signal characteristics of the mass are similar to CSF and there is no enhancement.

• Fig. 57.103 Epidermoid (pearly tumour) in the left temporal region. (A) At L36, W80. (B) Same case at L8, W1.

• Fig. 57.104 Epidermoid (arrow) of left cerebellopontine angle.

• Fig. 57.105 Epidermoid. (A) Sagittal MRI (T,-weighted). An irregular tumour in the pontine cistern is displacing the pons and appears to be invading it. (B) Axial MRI (T 2-weighted). The tumour is shown as high signal displacing and compressing the central pons.

• Fig. 57.106 (A,B) Basal dermoid arising from ethmoids. Note marginal calcification (arrow).

• Fig. 57.107 Dermoid. Sagittal (A) and coronal (B) MRI sections (T,-weighted) demonstrate small ovoid mass in lower vermis with high signal in lower part and low signal in upper part.

• Fig. 57.108 Colloid cysts. (A) Small high-density cyst at base of septum pellucidum. This is the classic appearance seen in most cases. (B) Isodense cyst with marginal enhancement after contrast medium-a rare variant. (C) Coronal MRI study (T,-weighted) shows the cyst as a high-signal lesion in the third ventricle. (Courtesy of Dr Gordon Thomson and Bristol MRI Centre.)

• . Fig. 57.109 Axial T2- weighted image (A) showing a rounded mass, slightly hyperintense to brain in the hypothalamic region consistent with a hamartoma. The mass is isointense to brain on the T,-weighted post contrast image (B) and does not enhance.