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Supratentorial space-occupying lesions
Supratentorial
Space-occupying
Lesions
By NORMAN E. LEEDS, M.D.
II3 ENCEPHALOGRAPHY is used with decreasing frequency irk the investigation of supratentorial lesions, particularly when there are localizmg signs clinically or on brain scan. The pneumoencephalogram, however, is ~til.I of great value when the lesion is parasagittal, paracentral, or within a ventricle. Structural changes in the margins of t&e ventricles, in the c&iguration of the ventricular roof, and in the relationship of the septum pellucidrun to the third ventricle, as well as the size of the ventricles are important in the evaluation of the air study. The effects of a lesion on the ventricular system will, of course, depend on its location. The following discussion, therefore, will be subdivided according to the anatomic site of the offending mass.
A
TECHNICAL CONSIDERATIOR’S
It is essential for adequate evaluation to have enough air in the ventricles and that nonrotated films at right angles to each other in each projection be available.lr5 If no air is observed within the lateral ventricles despite adequate technique and positioning, there is a 50 per cent chance of a lesion being present. This probability becomes 75 per cent if a second pneumoencephalogram also fails to show ventricular air.7 In some of these patients, the inability to fill the ventricles may be a consequence of cerebral edema. Agents that reduce cerebral edema, such as mannitol or urea, may then shrink the brain and promote ventricular filling.” In patients with nonfilling of the ventricles, the appearance of the subarachnoid cisterns may aid in indicating the presence and even the location of a lesion.‘~5~” When a supratentorial mass is suspected, patient monitoring should be optimal throughout the examination because of the potential of change in intracranial dynamics with the development of an in&Ural hemiation. RADJOLOGIC EVALUATION
Conuexity
Lesions
The relationship of the septum pellucidum to the third ventricle is most important in determining the location of these lesions, The axis of the septum pellucidum varies with the position of the convexity mass.‘.“,” With a high convexity lesion, displacement is greatest at the superior aspect of the septum and a tilt is observed (Fig. 1). When the lesion is lower, the greatest septal displacement is also lower and the septum becomes bowed (Fig. 2). With a temporal convexity lesion, the inferior aspect of the septum may be displaced NORMAN E. LEEDS, M.D.: Medical Center, Bronx, N. Y.
138
Head,
Sccticm
of Nectrorudiology,
hfontefiore
SEMINARS IN ROENTGENOLOCY, VOL.S,NO.Z
Hospital
and
(A~~~),1970
SUPRATENTOFUAL
SPACE-OCCUPYING
LJZSIOXS
139
Fig. 1. - High right convexity meningioma. Anteroposterior brow - up (A) and lateral sitting (B) projections. There is a tilt of the septum, especially the superior aspect, indicating a high convexity lesion. Flattening and depression of the roof of the right lateral
ventricle are due-to displacement under the faIx (arrow).
to a greater degree (Fig. 3). Th us, the location of the lesion is defined by the septal segment most displaced. Posterior convexity lesions may displace the septum, but it is straight or only slightly bowed and there is equal displacement of the third ventricle (see Fig. 6A). The third ventricle may actually be displaced more than the septum with posterior lesions that extend deeply (see Fig. 10). Diffuse displacement of the ventricles without local alteration is also observed with peripheral lesions. Depression of the roof may occur as a consequence of a shift under the falx (Figs. 1, 2 and 3). As the depth of the lesion increases, the displacement of the ventricle becomes more focal as a result of direct compression. The degree of localized displacement indicates the depth of the cortical extension. With a parasagittal or falx lesion, depression of the roof of the lateral ventricle is secondary to the direct pressure exerted by the lesion, Unlike the diffuse depression under the falx in convexity lesions (Figs. 1 to 3), there is a
NORMAN
E. LEEDS
midconvekity Fig. 2.-Left lesion. Solitary metastasis from carcinoma of the colon. Upright posteroanterior (A) and lateral (B) projections. The septum pellucidum is bowed to the right, with the greatest displacement just below the most cephalic area (arrows). There is a diffuse depression of the roof of the left lateral ventricle due to displacement under the falx.
localized flattening (Fig. 4) .I(’ The septum pellucidum, though shifted, is straight or only slightly angled, depending upon the depth of the lesion. In the temporal region, the position of the temporal horn is also important. It may be displaced medially, laterally, superiorly, or inferiorly.3 Again, there may be actual distortion or compression, indicating deep extension (Fig. 5). Herniation under the falx may also be observed with temporal tumors (Fig. 3). To evaluate involvement of a temporal horn, in addition to the routine radiographic projections ( perorbital, 25O angled Towne and lateral) ,S laminagraphy is being used with increasing frequency (Fig. 5B). Occipital lesions may produce forward displacement of the atrium of the lateral ventricle. There may also be a defect in the posterior portion of the lateral ventricle or the occipital horn (Fig. 6). However, indentation of the occipital horn may occur as a normal variant (calcar avis) (Fig. 6C and 16B).
SUPRATENTORIAL
SPACE-OCCUPYING
LESIONS
141
Fig. 3.-Temporal lobe glioblastoma. Anteroposterior brow-up projection. Note marked bowing of the septum pellucidum and third ventricle, with the inferior septum most displaced (arrows). There is marked depression of roof of the lateral ventricle by the falx.
Fig. 4.-Bilateral falx meningioma. Brow-down posteroanterior projection. The direct downward compression of the lateral ventricle is due to the proximity of the mass (arrows). The compression is primarily downward, indicating its parasagittal location. There is also compression of the opposite lateral ventricle (arrowhead), indicating bilaterality and thus suggesting the presence of a falx lesion.
NORMAN
E. LEEDS
Fig. 5.-Right temporal lobe glioblastoma. A. An-
teroposterior brow-up perorbital projection, Note the normal left temporal horn with normal lateral cleft (1) and supracornual cleft (s). On the right, there is evidence of a mass in the hippocampus M with distortion and enlargement of the temporal horn (arrows). The lateral angle of the right lateral ventricle is elevated (arrowhead). B. Laminagram. The mass indents the supracornual cleft superiorly and inferiorly (arrows) and flattens, enlarges, and distorts the lateral cleft (arrowhead).
equal straight shift of the septum pellucidum
there will usually be an and third ventricle (Fig. 6A).
Pamcentral Lesions In the paracentral lesion, which most commonly arises within the basal ganglia or thalamus, the difference in displacement of the septum and third ventricle is a factor in accurate localization.” A space-occupying lesion in the region of the basal ganglia, because of its apposition to the lateral ventricle, will cause greater displacement of the septum pellucidurn than of the third ventricle, with bowing of both structures (Fig. 7A). It may also locally distort the lateral ventricle. As a tumor enlarges, it may undergo necrosis and cavitate. The cavity may communicate with the ventricle and fill with air during pneumoencephalography (Fig. 7). This type of cavity is distinguished from a porencephalic cyst by the presence of a mass as part of the air-filled lesion. With a thalamic lesion, the third ventricle is usually straight or slightly bowed and displaced more than the septum.!’ If the lesion extends to the medial aspect of the thalamus, there may be focal indentation of the wall (Fig. 8). Elevation and impression of the floor of the posterior portion of the lateral ventricle in the region of the trigone and widening of the space between the posterior portion of the temporal horn and the atrium (Fig. 9) also occur. As the ventricle enlarges, displacement of the floor may become less apparent on the brow-down lateral projection. A lesion in the region of the trigone may result in changes similar to those of thalamic mass (Fig. 10).
SUPRA‘I’ENTORIAL
SPACE-OCCUPYING
Fig. G.-Malignant left occipital gIioma extending deepIy toward the ventricle. A. Brow-up anteroposterior projection. There is equal displacement of the septum and third ventricle to the right. l+ ventricular dilatation is present. B. Sittin lateral and (C) brow-down latera P projections. The left lateral ventricle is depressed with forward displacement of the trigone (black arrow). Localized flattening and posterior irregularity are seen in the vicinity of the occipital horn (arrowhead) indicating deep extension of the lesion. There is a smooth indentation of the posterior aspect of the lateral ventricle on the right (calcar avis) (white arrow).
LESIONS
NORMAN
E. LEEDS
Fig. 7.-Glioblastoma multiforme involving the left basal ganglia with exten sion into th le thalamus. A. Brow-up anteroposterior projection. Marked bowing of the septum pellucidurn and third ventricle with greater displacement of the infc :rior septum (arrowhead). There is compression of the lateral angle and body of the left lateral ventricle. A large round collection of air is observed adjacent to the lai teral ventric’ le and communicating with it (arrows). A ventricular cannula lies in this cavitv. B. Lateral hanging-head projection. The cavitary lesion lies within the 1:nasal gangha . An irregular mass is observed in the posterior wall of the cavity (arro IWS). Several ! small collections of air are present within the mass.
SUPRATENTORIAL
SPACE-OCCUPYING
LESIONS
145
Fig. S.-Right thalamic Anteroposterior glioma. brow-up projection. Small lobulated elevation of the floor of the body of the lateral ventricle (arrow). The third ventricle is indented and displaced by a lobulated mass. The septum is not deviated. There is 2 to 3’ ventricular dilatation.
lntraventricular
Lesions
Intraventricular tumors are uncommon and are difficult to diagnose clinically. They may arise within the ventricles, e.g., ependymoma, choroid plexus papilloma, meningioma, and epidermoid (cholesteatoma) .e There is nothing characteristic about these masses except for the epidermoid, which appears as a polypoid mass with a soap bubble configuration as a result of interposition of air among tumor fronds (Fig. 11). A lesion arising in the ventricular wall is usually a hematoma or subependymal glioma. It presents a localized smooth intramural elevation (Fig. 12). Finally, an ependymoma or a malignant tumor may cause marked ventricular deformity (Fig. 13). These lesions usually arise within the ventricle and grow outward but may invade the ventricle from the cortex.
Posterior Third Ventricular and lncisural Lesions Posterior third ventricle tumors and incisural tumors are discussed together because of their similar appearance on the air study. These lesions include arachnoid cyst, vein of Galen aneurysm, meningioma, pinealoma, quadrigeminal plate glioma, and thalamic tumor.‘.” On the air study, all may look similar, with a smooth mass indenting the posterior portion of the third ventricle and effacing the pineal recess (Fig. 14). Lateral incisural masses may produce a cutoff of the posterolateral aspect of the third ventricle on the brow-up or brow-down projections (Fig. 15) .’ A lesion involving the superior aspect of the tentorium not only distorts the posterior third ventricle but will produce a compression defect on the posterior portion of the lateral ventricles so that on the PA view the medial segments appear less dense than normal ( Fig. 16).
146
NORMAN
E. LEEDS
Fig. 9.-Tuberculoma af the left thalamus. BIrowdown posteroanterior (A) and lateral (B) projections re:veal a smooth mass elevating and compressing the floor of the trigone (arrows) and the latera1 ventricle.
SUPRATENTO~L
SPACE-OCCUPYING
LEsIONS
Fig. IO.-Left periatrial hematoma. A. Brow-down
posteroanterior projection. A mass indents the medial and inferior aspect of the atrium of the lateral ventricle (small arrows). There is a suggestion of obstruction to the posterior aspect of the temporal horn by the mass (large arrow). B. Anteroposterior brow-up projection. There is only partial obstruction of the temporal horn since the anterior portion of the temporal horn is filled. The lateral angle of the lateral ventricle is compressed. The septum pellucidum is bowed, with the caudal aspect displaced most. The third ventricle was observed to be displaced more than the septum on other
films.
REFERENCES 1. Davidoff, L. M., and Dyke, C. G.: The Normal Encephalogram. Philadelphia, Lea and Febiger, 1951. 2. Davidoff, L. M., and Epstein, B. S.: The Abnormal Pneumoencephalogram. Philadelphia, Lea and Febiger, 1950. 3. Lindgren, E.: A pneumographic study of the temporal horn with special reference to tumours in the temporal region. Acta Radiol. Suppl. 69, 1948. 4. Lindgren, E.: Radiologic examination of the brain and spinal cord. Acta Radiol. Suppl. 151, 1957. 5. Robertson, E. G.: Pneumoencephalography. Springfield, Ill., Charles C Thomas, 1957. 6. Ruggiero, G.: Encephalography today:
Refinements in technique and progress in
diagnosis. Acta Radiol. 5:705, 1966. 7. Taveras, J. M.: Personal communication. 8. Taveras, J. M.: The roentgen diagnosis of intracranial incisural space occupying lesions. Amer. J. Roentgen. 84:52, 1960. 9. Taveras, J. M., and Wood, E. H.: Diagnostic Neuroradiology. Baltimore, Md., Williams and Wilkins Co., 1964. 10. Wickbom, I.: Angiography and pneumography in the diagnosis of slightly spaceoccupying supratentorial turnours. Acta Radial. 46:158, 1956. 11. Zingesser, L. H., and Schechter, M. 14.: The radiology of masses lying within and adjacent to the tentorial hiatus. Brit. J. Radio]. 37:486, 1964.
NORMAN
E. LEEDS
E5g. 1 l.-Epidermoid (cholesteatomn) in the right temporal horn. Brow-l “P To\? me lateral (B) projections. The temporal horn is enlarged and conta iinsla-l irreg UL3 1’ Inass with A soap Ix~l~l~le pattern (arrows): The Iaternl angle of t he late ml ven tric :le is elevated (arrowhead).
(A) all Id
SUl’RATENTORIAL
SPACE-OCCUPYING
LESIOXS
149
Fig. 12.-Right subependymal hematoma. Lateral brow-up projection. A smoothly defined mass arises from the floor of the lateral ventricle just behind the foramen of Monro (arrows).
Fig. 13.-Malignant glioma of the corpus callosum with extension into the lateral ventricle. Anteroposterior brow-up projection. There is separation of the lateral ventricles with irregularity of the margins due to involvement of the septum pellucidum by the intruding tumor. The roof of each ventricle is depressed and distorted, indicating involvement of the corpus callosum as well,
150
NORMAN
EGg. 1,4.-Pinealoma. Lateral ventriculogram. There is effacement of the calcified pineal (p). rect ?SS(aI-row) with retrodisplacement
E. LEEDS
of the
lea1
F ‘ig. Lhcisural meningioma. Anteroposterior brow-up projection. The cu toff of the ri,&’ : lateral aspect of the third ventricle (arrows) is due to an antera’ blah:ral inci isw :a1 mass.
SUPRATENTORIAL
SPACE-OCCUPYING
Fig. 16.~Incisud meningioma. A. Brow-down posteroanterior projection. A symmetrical mass (arrows) encroaches on the medial aspect of each lateral ventricle. B. Lateral projection. The mass (small arrows) has produced an image of decreased radiolucency in the atrium. A smooth mass indents the posterior aspect of the third ventricle and displaces the aqueduct forward. The ventricles are enlarged. The defect at the posterior margin Of the lateral ventricle (large arrow) is the calcar avis.
LESIONS
151
Space-occupying
Lesions
By NORMAN E. LEEDS, M.D.
II3 ENCEPHALOGRAPHY is used with decreasing frequency irk the investigation of supratentorial lesions, particularly when there are localizmg signs clinically or on brain scan. The pneumoencephalogram, however, is ~til.I of great value when the lesion is parasagittal, paracentral, or within a ventricle. Structural changes in the margins of t&e ventricles, in the c&iguration of the ventricular roof, and in the relationship of the septum pellucidrun to the third ventricle, as well as the size of the ventricles are important in the evaluation of the air study. The effects of a lesion on the ventricular system will, of course, depend on its location. The following discussion, therefore, will be subdivided according to the anatomic site of the offending mass.
A
TECHNICAL CONSIDERATIOR’S
It is essential for adequate evaluation to have enough air in the ventricles and that nonrotated films at right angles to each other in each projection be available.lr5 If no air is observed within the lateral ventricles despite adequate technique and positioning, there is a 50 per cent chance of a lesion being present. This probability becomes 75 per cent if a second pneumoencephalogram also fails to show ventricular air.7 In some of these patients, the inability to fill the ventricles may be a consequence of cerebral edema. Agents that reduce cerebral edema, such as mannitol or urea, may then shrink the brain and promote ventricular filling.” In patients with nonfilling of the ventricles, the appearance of the subarachnoid cisterns may aid in indicating the presence and even the location of a lesion.‘~5~” When a supratentorial mass is suspected, patient monitoring should be optimal throughout the examination because of the potential of change in intracranial dynamics with the development of an in&Ural hemiation. RADJOLOGIC EVALUATION
Conuexity
Lesions
The relationship of the septum pellucidum to the third ventricle is most important in determining the location of these lesions, The axis of the septum pellucidum varies with the position of the convexity mass.‘.“,” With a high convexity lesion, displacement is greatest at the superior aspect of the septum and a tilt is observed (Fig. 1). When the lesion is lower, the greatest septal displacement is also lower and the septum becomes bowed (Fig. 2). With a temporal convexity lesion, the inferior aspect of the septum may be displaced NORMAN E. LEEDS, M.D.: Medical Center, Bronx, N. Y.
138
Head,
Sccticm
of Nectrorudiology,
hfontefiore
SEMINARS IN ROENTGENOLOCY, VOL.S,NO.Z
Hospital
and
(A~~~),1970
SUPRATENTOFUAL
SPACE-OCCUPYING
LJZSIOXS
139
Fig. 1. - High right convexity meningioma. Anteroposterior brow - up (A) and lateral sitting (B) projections. There is a tilt of the septum, especially the superior aspect, indicating a high convexity lesion. Flattening and depression of the roof of the right lateral
ventricle are due-to displacement under the faIx (arrow).
to a greater degree (Fig. 3). Th us, the location of the lesion is defined by the septal segment most displaced. Posterior convexity lesions may displace the septum, but it is straight or only slightly bowed and there is equal displacement of the third ventricle (see Fig. 6A). The third ventricle may actually be displaced more than the septum with posterior lesions that extend deeply (see Fig. 10). Diffuse displacement of the ventricles without local alteration is also observed with peripheral lesions. Depression of the roof may occur as a consequence of a shift under the falx (Figs. 1, 2 and 3). As the depth of the lesion increases, the displacement of the ventricle becomes more focal as a result of direct compression. The degree of localized displacement indicates the depth of the cortical extension. With a parasagittal or falx lesion, depression of the roof of the lateral ventricle is secondary to the direct pressure exerted by the lesion, Unlike the diffuse depression under the falx in convexity lesions (Figs. 1 to 3), there is a
NORMAN
E. LEEDS
midconvekity Fig. 2.-Left lesion. Solitary metastasis from carcinoma of the colon. Upright posteroanterior (A) and lateral (B) projections. The septum pellucidum is bowed to the right, with the greatest displacement just below the most cephalic area (arrows). There is a diffuse depression of the roof of the left lateral ventricle due to displacement under the falx.
localized flattening (Fig. 4) .I(’ The septum pellucidum, though shifted, is straight or only slightly angled, depending upon the depth of the lesion. In the temporal region, the position of the temporal horn is also important. It may be displaced medially, laterally, superiorly, or inferiorly.3 Again, there may be actual distortion or compression, indicating deep extension (Fig. 5). Herniation under the falx may also be observed with temporal tumors (Fig. 3). To evaluate involvement of a temporal horn, in addition to the routine radiographic projections ( perorbital, 25O angled Towne and lateral) ,S laminagraphy is being used with increasing frequency (Fig. 5B). Occipital lesions may produce forward displacement of the atrium of the lateral ventricle. There may also be a defect in the posterior portion of the lateral ventricle or the occipital horn (Fig. 6). However, indentation of the occipital horn may occur as a normal variant (calcar avis) (Fig. 6C and 16B).
SUPRATENTORIAL
SPACE-OCCUPYING
LESIONS
141
Fig. 3.-Temporal lobe glioblastoma. Anteroposterior brow-up projection. Note marked bowing of the septum pellucidum and third ventricle, with the inferior septum most displaced (arrows). There is marked depression of roof of the lateral ventricle by the falx.
Fig. 4.-Bilateral falx meningioma. Brow-down posteroanterior projection. The direct downward compression of the lateral ventricle is due to the proximity of the mass (arrows). The compression is primarily downward, indicating its parasagittal location. There is also compression of the opposite lateral ventricle (arrowhead), indicating bilaterality and thus suggesting the presence of a falx lesion.
NORMAN
E. LEEDS
Fig. 5.-Right temporal lobe glioblastoma. A. An-
teroposterior brow-up perorbital projection, Note the normal left temporal horn with normal lateral cleft (1) and supracornual cleft (s). On the right, there is evidence of a mass in the hippocampus M with distortion and enlargement of the temporal horn (arrows). The lateral angle of the right lateral ventricle is elevated (arrowhead). B. Laminagram. The mass indents the supracornual cleft superiorly and inferiorly (arrows) and flattens, enlarges, and distorts the lateral cleft (arrowhead).
equal straight shift of the septum pellucidum
there will usually be an and third ventricle (Fig. 6A).
Pamcentral Lesions In the paracentral lesion, which most commonly arises within the basal ganglia or thalamus, the difference in displacement of the septum and third ventricle is a factor in accurate localization.” A space-occupying lesion in the region of the basal ganglia, because of its apposition to the lateral ventricle, will cause greater displacement of the septum pellucidurn than of the third ventricle, with bowing of both structures (Fig. 7A). It may also locally distort the lateral ventricle. As a tumor enlarges, it may undergo necrosis and cavitate. The cavity may communicate with the ventricle and fill with air during pneumoencephalography (Fig. 7). This type of cavity is distinguished from a porencephalic cyst by the presence of a mass as part of the air-filled lesion. With a thalamic lesion, the third ventricle is usually straight or slightly bowed and displaced more than the septum.!’ If the lesion extends to the medial aspect of the thalamus, there may be focal indentation of the wall (Fig. 8). Elevation and impression of the floor of the posterior portion of the lateral ventricle in the region of the trigone and widening of the space between the posterior portion of the temporal horn and the atrium (Fig. 9) also occur. As the ventricle enlarges, displacement of the floor may become less apparent on the brow-down lateral projection. A lesion in the region of the trigone may result in changes similar to those of thalamic mass (Fig. 10).
SUPRA‘I’ENTORIAL
SPACE-OCCUPYING
Fig. G.-Malignant left occipital gIioma extending deepIy toward the ventricle. A. Brow-up anteroposterior projection. There is equal displacement of the septum and third ventricle to the right. l+ ventricular dilatation is present. B. Sittin lateral and (C) brow-down latera P projections. The left lateral ventricle is depressed with forward displacement of the trigone (black arrow). Localized flattening and posterior irregularity are seen in the vicinity of the occipital horn (arrowhead) indicating deep extension of the lesion. There is a smooth indentation of the posterior aspect of the lateral ventricle on the right (calcar avis) (white arrow).
LESIONS
NORMAN
E. LEEDS
Fig. 7.-Glioblastoma multiforme involving the left basal ganglia with exten sion into th le thalamus. A. Brow-up anteroposterior projection. Marked bowing of the septum pellucidurn and third ventricle with greater displacement of the infc :rior septum (arrowhead). There is compression of the lateral angle and body of the left lateral ventricle. A large round collection of air is observed adjacent to the lai teral ventric’ le and communicating with it (arrows). A ventricular cannula lies in this cavitv. B. Lateral hanging-head projection. The cavitary lesion lies within the 1:nasal gangha . An irregular mass is observed in the posterior wall of the cavity (arro IWS). Several ! small collections of air are present within the mass.
SUPRATENTORIAL
SPACE-OCCUPYING
LESIONS
145
Fig. S.-Right thalamic Anteroposterior glioma. brow-up projection. Small lobulated elevation of the floor of the body of the lateral ventricle (arrow). The third ventricle is indented and displaced by a lobulated mass. The septum is not deviated. There is 2 to 3’ ventricular dilatation.
lntraventricular
Lesions
Intraventricular tumors are uncommon and are difficult to diagnose clinically. They may arise within the ventricles, e.g., ependymoma, choroid plexus papilloma, meningioma, and epidermoid (cholesteatoma) .e There is nothing characteristic about these masses except for the epidermoid, which appears as a polypoid mass with a soap bubble configuration as a result of interposition of air among tumor fronds (Fig. 11). A lesion arising in the ventricular wall is usually a hematoma or subependymal glioma. It presents a localized smooth intramural elevation (Fig. 12). Finally, an ependymoma or a malignant tumor may cause marked ventricular deformity (Fig. 13). These lesions usually arise within the ventricle and grow outward but may invade the ventricle from the cortex.
Posterior Third Ventricular and lncisural Lesions Posterior third ventricle tumors and incisural tumors are discussed together because of their similar appearance on the air study. These lesions include arachnoid cyst, vein of Galen aneurysm, meningioma, pinealoma, quadrigeminal plate glioma, and thalamic tumor.‘.” On the air study, all may look similar, with a smooth mass indenting the posterior portion of the third ventricle and effacing the pineal recess (Fig. 14). Lateral incisural masses may produce a cutoff of the posterolateral aspect of the third ventricle on the brow-up or brow-down projections (Fig. 15) .’ A lesion involving the superior aspect of the tentorium not only distorts the posterior third ventricle but will produce a compression defect on the posterior portion of the lateral ventricles so that on the PA view the medial segments appear less dense than normal ( Fig. 16).
146
NORMAN
E. LEEDS
Fig. 9.-Tuberculoma af the left thalamus. BIrowdown posteroanterior (A) and lateral (B) projections re:veal a smooth mass elevating and compressing the floor of the trigone (arrows) and the latera1 ventricle.
SUPRATENTO~L
SPACE-OCCUPYING
LEsIONS
Fig. IO.-Left periatrial hematoma. A. Brow-down
posteroanterior projection. A mass indents the medial and inferior aspect of the atrium of the lateral ventricle (small arrows). There is a suggestion of obstruction to the posterior aspect of the temporal horn by the mass (large arrow). B. Anteroposterior brow-up projection. There is only partial obstruction of the temporal horn since the anterior portion of the temporal horn is filled. The lateral angle of the lateral ventricle is compressed. The septum pellucidum is bowed, with the caudal aspect displaced most. The third ventricle was observed to be displaced more than the septum on other
films.
REFERENCES 1. Davidoff, L. M., and Dyke, C. G.: The Normal Encephalogram. Philadelphia, Lea and Febiger, 1951. 2. Davidoff, L. M., and Epstein, B. S.: The Abnormal Pneumoencephalogram. Philadelphia, Lea and Febiger, 1950. 3. Lindgren, E.: A pneumographic study of the temporal horn with special reference to tumours in the temporal region. Acta Radiol. Suppl. 69, 1948. 4. Lindgren, E.: Radiologic examination of the brain and spinal cord. Acta Radiol. Suppl. 151, 1957. 5. Robertson, E. G.: Pneumoencephalography. Springfield, Ill., Charles C Thomas, 1957. 6. Ruggiero, G.: Encephalography today:
Refinements in technique and progress in
diagnosis. Acta Radiol. 5:705, 1966. 7. Taveras, J. M.: Personal communication. 8. Taveras, J. M.: The roentgen diagnosis of intracranial incisural space occupying lesions. Amer. J. Roentgen. 84:52, 1960. 9. Taveras, J. M., and Wood, E. H.: Diagnostic Neuroradiology. Baltimore, Md., Williams and Wilkins Co., 1964. 10. Wickbom, I.: Angiography and pneumography in the diagnosis of slightly spaceoccupying supratentorial turnours. Acta Radial. 46:158, 1956. 11. Zingesser, L. H., and Schechter, M. 14.: The radiology of masses lying within and adjacent to the tentorial hiatus. Brit. J. Radio]. 37:486, 1964.
NORMAN
E. LEEDS
E5g. 1 l.-Epidermoid (cholesteatomn) in the right temporal horn. Brow-l “P To\? me lateral (B) projections. The temporal horn is enlarged and conta iinsla-l irreg UL3 1’ Inass with A soap Ix~l~l~le pattern (arrows): The Iaternl angle of t he late ml ven tric :le is elevated (arrowhead).
(A) all Id
SUl’RATENTORIAL
SPACE-OCCUPYING
LESIOXS
149
Fig. 12.-Right subependymal hematoma. Lateral brow-up projection. A smoothly defined mass arises from the floor of the lateral ventricle just behind the foramen of Monro (arrows).
Fig. 13.-Malignant glioma of the corpus callosum with extension into the lateral ventricle. Anteroposterior brow-up projection. There is separation of the lateral ventricles with irregularity of the margins due to involvement of the septum pellucidum by the intruding tumor. The roof of each ventricle is depressed and distorted, indicating involvement of the corpus callosum as well,
150
NORMAN
EGg. 1,4.-Pinealoma. Lateral ventriculogram. There is effacement of the calcified pineal (p). rect ?SS(aI-row) with retrodisplacement
E. LEEDS
of the
lea1
F ‘ig. Lhcisural meningioma. Anteroposterior brow-up projection. The cu toff of the ri,&’ : lateral aspect of the third ventricle (arrows) is due to an antera’ blah:ral inci isw :a1 mass.
SUPRATENTORIAL
SPACE-OCCUPYING
Fig. 16.~Incisud meningioma. A. Brow-down posteroanterior projection. A symmetrical mass (arrows) encroaches on the medial aspect of each lateral ventricle. B. Lateral projection. The mass (small arrows) has produced an image of decreased radiolucency in the atrium. A smooth mass indents the posterior aspect of the third ventricle and displaces the aqueduct forward. The ventricles are enlarged. The defect at the posterior margin Of the lateral ventricle (large arrow) is the calcar avis.
LESIONS
151