Neuroradiology 10, 243-249 (1976) © by Springer-Verlag 1976
Angiotomographic Study of the Normal Cerebral Circulation II. The Vertebrobasilar System M. Rosa Radiological Departments of the St. Martino Hospital and of the University of Genoa, Italy, and Neurosurgical Clinic of the University of Genoa, Italy Received: November 25, 1975 Summary. Simultaneous tomography applied to normal vertebral angiography has, by the dissociation of the vascular planes, made a selective and spatial study of the vertebrobasilar circulation possible, and therefore the identification of the vessels which are partly or totally hidden by other vascular structures. This technique has also led to a better delimitation and sometimes a direct observation and spatial localization of some anatomical structures above and below the tentorium. Etude angiotomographique de la circulation cdrObrale normale. SystOme vertdbro-basilaire Rdsumd. La tomographie simultande, appliqu6e ~ l'angiographie
vert6brale, a permis, par la dissociation des plans vasculalres, une 6tude sdlective et spatiale des vaisseaux de la circulation vert6brobasilaire et donc l'identification des vaisseaux qui sont partiellement ou totalement cach6s par d'autres structures vasculaires. Cette Progress in the knowledge of the normal r a d i o a n a t o m y of the vertebrobasilar circulation has led to a remarkable i m p r o v e m e n t in the evaluation of vertebral angiography. However, on the standard vertebral angiograms, the superposition of the vascular structures limits the precise identification of some vessels, especially in the lateral projection [5, 13, 14]. Simultaneous t o m o g r a p h y applied to vertebral angiography - making dissociation of the vascular planes possible - helps us to overcome this drawback [1,2, 3 , 4 , 6 , 7 , 8 , 9 , 10, 11, 12]. The purpose of the present p a p e r is the angiotomographic study of the vertebrobasilar circulation, aiming to complete the criteria of evaluation of the normal radioanatomical picture by selective and spatial analysis.
Material and Method This angiotomographic study was made on 25 patients with normal standard vertebral angiograms. The radiological apparatus and technique for the simultaneous t o m o g r a p h y used in this research are the same as described in our previous p a p e r [8]. Retrograde brachial angiography was used for demonstration of the vertebrobasilar circulation in most of the cases; the femoral catheter m e t h o d was applied in a
technique a permis aussi une meilleure d61imitation et parfois une observation directe et une localisation spatiale de certaines structures anatomiques au-dessus et au-dessous de la tente. Angiotomographisches Studium des normalen zerebralen Kreislaufs. Vertebrobasilares System Zusammenfassung. Die simultane an der Vertebralangiographie
angewandte Tomographie hat durch die Dissoziation der Gef~if3ebenen eine selektive und r/iumliehe Untersuchung der Gefiige des vertebrobasilaren Kreislaufs und folglich der Gef~ige erm6glicht, die zum Teil oder vollst/indig durch andere vaskularen Strukturen versteckt werden. Diese Methode hat auch eine bessere Abgrenzung und manchreal eine direkte Beobachtung, sowie eine r~iumliche Bestimmung einiger anatomischer Strukturen fiber und unter dem Tentorium erlaubt. few cases. Standard angiography always preceded the angiotomographic examination in order to establish the levels of the sections to be made. The sagittal and coronal sections, made at 0.5 cm intervals, were planned on the basis of the findings observed in the A P and lateral projections of the standard angiograms, with special reference to the relationship between the vessels and the bone structures of the posterior fossa.
Results The application of simultaneous t o m o g r a p h y to vertebral angiography has m a d e it possible to observe the arterial and venous vessels of the vertebrobasilar system on different planes and at a constant distance. However, the vessels were observed segmentally or in section because, by this technique, only the portions of the vessels situated on the objective plane are visible, whereas the portions situated outside such plane are not recorded. The segments of the vessels observed were longer or shorter depending on their relative length in the same plane. The vessels running perpendicular to the tomographic plane were seen in section. The dissociation of the vascular planes of the vertebrobasilar system obtained by sagittal sections was found to be very useful because it allowed selective and spatial study of the vessels of both sides and of those running in the median sagittal plane.
244
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
245
Fig. 2. a) Standard vertebral angiogram, arterial phase, lateral projection, b) Midline sagittal angiotomogram which permits a selective and spatial study of the superior and of the inferior vermian branches that delimit the outline of the vermis clearly
Due to the well known topographical variations in the frontal plane, the basilar artery was observed in the greater part of its course on the section corresponding to the midline, or segmentally on the median and the paramedian sections, depending on whether the artery had a straight course at the level of the midline, or a lateral, more or less accentuated, curved course. In both cases the relations between the basilar artery and the clivus could be determined with exactness (Fig. 1 d, e). The posterior cerebral arteries, the superior cerebellar arteries and their branches, which are seen superimposed on the standard vertebral angiograms, were studied in a selective manner by angiotomography. The prepeduncular portion of the posterior cerebral arteries and the prepontine portion of the superior cerebellar arteries were seen in cross section or in short segments because of their course, respectively perpendicular or oblique to the section. The ambient portion of the former, and the lateral pontine portion of the latter, as well as their branches, the
Fig. 3. Standard vertebral phlebogram, lateral projection
+--- Fig. 1. a) Standard vertebral angiogram, arterial phase, lateral projection, b-f) Sagittal simultaneous angiotomograms, made at 0.5 cm intervals, which start 1 cm from the left of the midline and proceed by 2 cm to the right. The posterior cerebral and the superior cerebellar arteries of both sides and their branches, superimposed on the standard angi0gram (a), are seen selectively, although segmentally, by angiotomography, b) The prepeduncular segment (1) of the left posterior cerebral artery, in cross section; the ambient segment (2), and the parieto-oceipital branch (3) of the left posterior cerebral artery; the lateral pontine segment (4) of the left superior cerebellar artery, c) A left medial superior hemispheric branch (1); the left calcarine artery (2). d) Section made at the level of the midline: the superior vermian branch (open arrow) and a medial tonsillar branch (straight arrow), e) Part of another vermian branch (straight arrows), f) Part of the prepeduncular (1) and of the midposterior ambient (2) segments of the right posterior cerebral artery, and part of the paramedian hemispheric branches (3-4) of the right superior cerebellar artery. Note that the basilar artery is seen segmentally on the median (d) and paramedian sections (e, f); therefore the relations between the basilar artery and the clivus may be clearly estimated
246
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
247
Fig. 5. a) Standard vertebral angiogram, arterial phase, AP projection. b-c) Coronal angiotomograms made at the level of the anterior part of the posterior fossa. The basilar artery is completely seen on the same tomographic section (b). The prepeduncular portion of the posterior cerebral arteries, the prepontine portion of the superior cerebellar arteries, and the internal auditory arteries (arrowheads) are segmentally seen (b-c). The observation on the same plane of the proximal part of the intracanalieular segment (straight arrow) of the left internal auditory artery, and of the internal auditory canal permits exact evaluation of their reciprocal spatial relations
course of which was predominantly sagittal, coincided in part with the sections and were thus seen in a longer extent. The anterior inferior cerebellar artery was seen in short segments when its course was oblique, and in cross section when its course was predominantly transverse (Fig. 1 a-f). The posterior inferior cerebellar artery was seen segmentally on the paramedian planes on which it is running with its medullary and tonsillar portions. The vermian and paravermian superior and inferior
branches, running especially on the median and paramedian sagittal planes of the posterior fossa, were observed on the sections corresponding to these planes without superposition of the hemispheric cerebellar and posterior temporal branches. This makes easier the identification of these vermian branches and of the outline of the vermis which is delimited by such branches (Fig. 2 b). Sagittal angiotomography has contributed substantially to the study of the vertebral phlebogram when
Fig. 4. Same case as Fig. 3. a-f) Sagittal simultaneous angiotomographic series, made at 0.5 cm intervals, starting 1 cm from the left and ending 1.5 cm to the right of the midline of the posterior fossa. Sections a) and b) have been made to the left of the midline, section c) on the midline, a) The superior segment of the lateral mesencephalic vein (1); the calcarine vein (2); the precunian vein (3). b) The posteromedial thalamic vein (1); the distal segment (2) of the calcarine vein; basilar plexus (3). c) Besides the internal cerebral and Galenic veins and the straight sinus, the medial ascending occipital veins (bent arrows), precentral cerebellar vein (1) and inferior vermian vein (2) are seen. The elimination of the vascular structures, outside this section, permits the identification of the anterior pontomesencephalic vein (3), the supraculminate vein (arrowheads) and its intraculminate (straight arrow) and preculminate (open arrow) tributaries and their precise point of confluence, and the anastomosis between the inferior vermian (2) and the declival (4) veins. The outlines of the interpeduncularfossa, of the ventral surface of the pons, and of the vermis are perfectly delineated by such veins; the evaluation of the median sagittal diameter of the isthmus of the mesencephalon (dotted line above) and of the pons (dotted line below) was easier and more correct because this section (c), chosen to measure them, corresponds to the midline. The sections d), e), f) have been made to the right of the midline, d) The medial ascending (bent arrow) and descending (straight arrow) occipital veins; the anterior medial thalamic vein (1); the pineal vein (2). The superior (3) and inferior (4) retrotonsillar veins, which outline the posterior margin of the cerebellar tonsil (T), empty into the inferior vermian vein. e) Part of the peduncular vein (arrow head), and descending cerebellar hemispheric branches (straight arrow), f) Anterior superior cerebellar vein (straight arrow)
248
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
Fig. 6. a-b) Coronal angiotomograms of the vertebral phlebogram. The precentral cerebellar (arrowhead, a) and Galenic (arrowhead, b) veins are seen segmentally but without overlapping the other venous structures of the midline
the superposition of the various venous systems makes the interpretation of the standard vertebral phlebogram difficult (Fig. 3). This technique was useful especially for the study of the midline venous systems. The anterior pontomesencephalic vein, the precentral cerebellar vein, the superior and inferior vermian veins, and their interlaminar tributaries were seen selectively, usually on the midline section of the posterior fossa. This makes the outlines of the interpeduncular fossa, of the ventral surface of the pons, and of the vermis clearly visible. Besides, the evaluation of the median sagittal diameter of the mesencephalon and of the pons was easier and more exact, because the section chosen to measure these diameters corresponded to the median sagittal plane of the posterior fossa (Fig. 4 c). Usually, a detailed study of the internal occipital veins, of the thalamic veins, of the pineal veins, of the posterior and lateral mesencephalic veins, of the superior and inferior retrotonsillar veins was obtained from the paramedian sections (Fig. 4a, b, d), while more lateral sections were used to study the cerebellar hemispheric veins (Fig. 4 e, f). On the coronal tomographic sections the vessels of the vertebrobasilar system, which showed a prevailing sagittal course, were generally seen in short segments or in cross section. Exceptions to this are the basilar artery, the prepeduncular portion of the posterior cerebral arteries and the prepontine portion of the superior cerebellar arteries and sometimes the anterior inferior cerebellar arteries which, running in a rather long course on the same tomographic plane, were seen in rather long portions. The precise identification of the portion of the an-
terior inferior cerebellar artery, situated at the level of the petrus bone apex, and of the intracanalicular portion of the internal auditory artery which follows the inferior wall of the internal auditory canal, was particularly interesting. The observation of these vascular and skeletal structures on the same plane permitted us to evaluate their reciprocal spatial relations exactly (Fig. 5b, c). Coronal angiotomography in the phlebogram has provided most interesting findings in the study of the precentral cerebellar vein (Fig. 6) by eliminating the vascular superpositions which often make the identification of this vein difficult, and sometimes even impossible. This finding is very important since the precentral cerebellar vein represents, as it is well known, the ideal landmark for the midline of the posterior fossa. This technique, moreover, made the detailed study of the other veins of the posterior fossa, and especially of those of the pontocerebellar angle, possible. In fact, it was possible to obtain better systematization of the tributaries of the petrosal vein and a more exact evaluation of the relations between this vein and the apex of the petrus bone. Coronal angiotomography has contributed substantially to the precise identification of the upper and lower limits of the posterior fossa, indicated respectively by the tentorial veins and the occipital bone, seen on the same section. Angiotomography, carried out during the capillary phase, sometimes demonstrated in section the pulvinar, the cuneus, the cerebellum, the cerebeUar tonsils and part of the 4th ventricle; the last may be seen as a negative image in the general picture of the opacified surrounding parenchymal structures.
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II Conclusions
Simultaneous tomography applied to normal vertebral angiography has made a substantial contribution to complete the evaluating criteria of the standard angiographic picture, because it has made possible: the observation of the vessels of the vertebrobasilar system on different planes at a constant and known distance, and therefore a spatial evaluation of such vessels; the evaluation of the skeletal and vascular structures on the same tomographic plane carrying out a selective study by eliminating those structures situated outside this plane; a better delimitation, and sometimes a direct observation of anatomical structures above and below the tentorium, and their spatial localization.
References
1. Cabanis, E.A., Calabro', A., Bonneville, J.F., Metzger, J., Ernest, C.: Angiotomographie. Trait6 de Radiodiagnostic, tome XIV-1. Paris: Masson 1975 2. Calabro', A.: Communication personnelle au IX6me Congr~sde Radiologie de Culture Latine. Venise, Octobre 1974 3. Du Boulay, G.M., Jackson, D.C.: Cranial angiotomography. Clin. Radiol. 16, 148-153 (1965) 4. Gerhard, P.: Tomography of the vertebro-basilar circulation. Roentgen Praxis 24, 49-53 (1971)
249
5. Legre, J., Dufour, M., Debaene, A.: L'art6riographie vert6brale. Trait6 de Radiodiagnostic, tome XIII. Paris: Masson 1972 6. Oldenkott, P., Gerhardt, P.: Angiotomography of the posterior fossa. Neuroradiology 2, 212-215 (1971) 7. Poole, G.J., Kramer, R. A.: Posterior fossa midline venotomography. 9th Annual Meeting of the American Society of Neuroradiology, 1971 8. Ramella, G., Rosa, M.: Angiotomographic study of the normal cerebral circulation. Internal carotid artery system. Neuroradiology 8, 15-23 (1974) 9. Ramella, G., Rosa, M.: Angiotomography of the angiomas of the posterior fossa. Communication at X Symposium Neuroradiologicum. Punta del Este, march 1974. Acta radiol. in press 10. Rosa, M.: Angiotomographie c6r6brale: radio-anatomie normale. J. Radiol. Electrol. 56, 199 (1975) 11. Rosa, M., Ramella, G.: Angiotomographie de la circulation vertdbro-basilaire: anatomie normale. Communication au IX~me Congr6s de Radiologie de Culture Latine. Venise, Octobre 1974. J. Radiol. t~lectrol, in press 12. Viano, J., Metzger, J., Pertuiset, B.: L'angiotomographie c6r6brale. Rev. Neurol. 125, 155-164 (1971) 13. Wackenheim, A., Braun, J.P.: Angiography of the mesencephalon. Berlin, Heidelberg, New York: Springer 1970 14. Wackenheim, A., Nakayama, N., Wende, S.: Magnification of the veins in vertebral angiography. Neuroradiology 6, 56-59 (1973) Doc. Dr. Marco Rosa Radiological Dept. of St. Martino Hospital and Neurosurgical Clinic of the University Genoa, Italy.
Angiotomographic Study of the Normal Cerebral Circulation II. The Vertebrobasilar System M. Rosa Radiological Departments of the St. Martino Hospital and of the University of Genoa, Italy, and Neurosurgical Clinic of the University of Genoa, Italy Received: November 25, 1975 Summary. Simultaneous tomography applied to normal vertebral angiography has, by the dissociation of the vascular planes, made a selective and spatial study of the vertebrobasilar circulation possible, and therefore the identification of the vessels which are partly or totally hidden by other vascular structures. This technique has also led to a better delimitation and sometimes a direct observation and spatial localization of some anatomical structures above and below the tentorium. Etude angiotomographique de la circulation cdrObrale normale. SystOme vertdbro-basilaire Rdsumd. La tomographie simultande, appliqu6e ~ l'angiographie
vert6brale, a permis, par la dissociation des plans vasculalres, une 6tude sdlective et spatiale des vaisseaux de la circulation vert6brobasilaire et donc l'identification des vaisseaux qui sont partiellement ou totalement cach6s par d'autres structures vasculaires. Cette Progress in the knowledge of the normal r a d i o a n a t o m y of the vertebrobasilar circulation has led to a remarkable i m p r o v e m e n t in the evaluation of vertebral angiography. However, on the standard vertebral angiograms, the superposition of the vascular structures limits the precise identification of some vessels, especially in the lateral projection [5, 13, 14]. Simultaneous t o m o g r a p h y applied to vertebral angiography - making dissociation of the vascular planes possible - helps us to overcome this drawback [1,2, 3 , 4 , 6 , 7 , 8 , 9 , 10, 11, 12]. The purpose of the present p a p e r is the angiotomographic study of the vertebrobasilar circulation, aiming to complete the criteria of evaluation of the normal radioanatomical picture by selective and spatial analysis.
Material and Method This angiotomographic study was made on 25 patients with normal standard vertebral angiograms. The radiological apparatus and technique for the simultaneous t o m o g r a p h y used in this research are the same as described in our previous p a p e r [8]. Retrograde brachial angiography was used for demonstration of the vertebrobasilar circulation in most of the cases; the femoral catheter m e t h o d was applied in a
technique a permis aussi une meilleure d61imitation et parfois une observation directe et une localisation spatiale de certaines structures anatomiques au-dessus et au-dessous de la tente. Angiotomographisches Studium des normalen zerebralen Kreislaufs. Vertebrobasilares System Zusammenfassung. Die simultane an der Vertebralangiographie
angewandte Tomographie hat durch die Dissoziation der Gef~if3ebenen eine selektive und r/iumliehe Untersuchung der Gefiige des vertebrobasilaren Kreislaufs und folglich der Gef~ige erm6glicht, die zum Teil oder vollst/indig durch andere vaskularen Strukturen versteckt werden. Diese Methode hat auch eine bessere Abgrenzung und manchreal eine direkte Beobachtung, sowie eine r~iumliche Bestimmung einiger anatomischer Strukturen fiber und unter dem Tentorium erlaubt. few cases. Standard angiography always preceded the angiotomographic examination in order to establish the levels of the sections to be made. The sagittal and coronal sections, made at 0.5 cm intervals, were planned on the basis of the findings observed in the A P and lateral projections of the standard angiograms, with special reference to the relationship between the vessels and the bone structures of the posterior fossa.
Results The application of simultaneous t o m o g r a p h y to vertebral angiography has m a d e it possible to observe the arterial and venous vessels of the vertebrobasilar system on different planes and at a constant distance. However, the vessels were observed segmentally or in section because, by this technique, only the portions of the vessels situated on the objective plane are visible, whereas the portions situated outside such plane are not recorded. The segments of the vessels observed were longer or shorter depending on their relative length in the same plane. The vessels running perpendicular to the tomographic plane were seen in section. The dissociation of the vascular planes of the vertebrobasilar system obtained by sagittal sections was found to be very useful because it allowed selective and spatial study of the vessels of both sides and of those running in the median sagittal plane.
244
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
245
Fig. 2. a) Standard vertebral angiogram, arterial phase, lateral projection, b) Midline sagittal angiotomogram which permits a selective and spatial study of the superior and of the inferior vermian branches that delimit the outline of the vermis clearly
Due to the well known topographical variations in the frontal plane, the basilar artery was observed in the greater part of its course on the section corresponding to the midline, or segmentally on the median and the paramedian sections, depending on whether the artery had a straight course at the level of the midline, or a lateral, more or less accentuated, curved course. In both cases the relations between the basilar artery and the clivus could be determined with exactness (Fig. 1 d, e). The posterior cerebral arteries, the superior cerebellar arteries and their branches, which are seen superimposed on the standard vertebral angiograms, were studied in a selective manner by angiotomography. The prepeduncular portion of the posterior cerebral arteries and the prepontine portion of the superior cerebellar arteries were seen in cross section or in short segments because of their course, respectively perpendicular or oblique to the section. The ambient portion of the former, and the lateral pontine portion of the latter, as well as their branches, the
Fig. 3. Standard vertebral phlebogram, lateral projection
+--- Fig. 1. a) Standard vertebral angiogram, arterial phase, lateral projection, b-f) Sagittal simultaneous angiotomograms, made at 0.5 cm intervals, which start 1 cm from the left of the midline and proceed by 2 cm to the right. The posterior cerebral and the superior cerebellar arteries of both sides and their branches, superimposed on the standard angi0gram (a), are seen selectively, although segmentally, by angiotomography, b) The prepeduncular segment (1) of the left posterior cerebral artery, in cross section; the ambient segment (2), and the parieto-oceipital branch (3) of the left posterior cerebral artery; the lateral pontine segment (4) of the left superior cerebellar artery, c) A left medial superior hemispheric branch (1); the left calcarine artery (2). d) Section made at the level of the midline: the superior vermian branch (open arrow) and a medial tonsillar branch (straight arrow), e) Part of another vermian branch (straight arrows), f) Part of the prepeduncular (1) and of the midposterior ambient (2) segments of the right posterior cerebral artery, and part of the paramedian hemispheric branches (3-4) of the right superior cerebellar artery. Note that the basilar artery is seen segmentally on the median (d) and paramedian sections (e, f); therefore the relations between the basilar artery and the clivus may be clearly estimated
246
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
247
Fig. 5. a) Standard vertebral angiogram, arterial phase, AP projection. b-c) Coronal angiotomograms made at the level of the anterior part of the posterior fossa. The basilar artery is completely seen on the same tomographic section (b). The prepeduncular portion of the posterior cerebral arteries, the prepontine portion of the superior cerebellar arteries, and the internal auditory arteries (arrowheads) are segmentally seen (b-c). The observation on the same plane of the proximal part of the intracanalieular segment (straight arrow) of the left internal auditory artery, and of the internal auditory canal permits exact evaluation of their reciprocal spatial relations
course of which was predominantly sagittal, coincided in part with the sections and were thus seen in a longer extent. The anterior inferior cerebellar artery was seen in short segments when its course was oblique, and in cross section when its course was predominantly transverse (Fig. 1 a-f). The posterior inferior cerebellar artery was seen segmentally on the paramedian planes on which it is running with its medullary and tonsillar portions. The vermian and paravermian superior and inferior
branches, running especially on the median and paramedian sagittal planes of the posterior fossa, were observed on the sections corresponding to these planes without superposition of the hemispheric cerebellar and posterior temporal branches. This makes easier the identification of these vermian branches and of the outline of the vermis which is delimited by such branches (Fig. 2 b). Sagittal angiotomography has contributed substantially to the study of the vertebral phlebogram when
Fig. 4. Same case as Fig. 3. a-f) Sagittal simultaneous angiotomographic series, made at 0.5 cm intervals, starting 1 cm from the left and ending 1.5 cm to the right of the midline of the posterior fossa. Sections a) and b) have been made to the left of the midline, section c) on the midline, a) The superior segment of the lateral mesencephalic vein (1); the calcarine vein (2); the precunian vein (3). b) The posteromedial thalamic vein (1); the distal segment (2) of the calcarine vein; basilar plexus (3). c) Besides the internal cerebral and Galenic veins and the straight sinus, the medial ascending occipital veins (bent arrows), precentral cerebellar vein (1) and inferior vermian vein (2) are seen. The elimination of the vascular structures, outside this section, permits the identification of the anterior pontomesencephalic vein (3), the supraculminate vein (arrowheads) and its intraculminate (straight arrow) and preculminate (open arrow) tributaries and their precise point of confluence, and the anastomosis between the inferior vermian (2) and the declival (4) veins. The outlines of the interpeduncularfossa, of the ventral surface of the pons, and of the vermis are perfectly delineated by such veins; the evaluation of the median sagittal diameter of the isthmus of the mesencephalon (dotted line above) and of the pons (dotted line below) was easier and more correct because this section (c), chosen to measure them, corresponds to the midline. The sections d), e), f) have been made to the right of the midline, d) The medial ascending (bent arrow) and descending (straight arrow) occipital veins; the anterior medial thalamic vein (1); the pineal vein (2). The superior (3) and inferior (4) retrotonsillar veins, which outline the posterior margin of the cerebellar tonsil (T), empty into the inferior vermian vein. e) Part of the peduncular vein (arrow head), and descending cerebellar hemispheric branches (straight arrow), f) Anterior superior cerebellar vein (straight arrow)
248
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II
Fig. 6. a-b) Coronal angiotomograms of the vertebral phlebogram. The precentral cerebellar (arrowhead, a) and Galenic (arrowhead, b) veins are seen segmentally but without overlapping the other venous structures of the midline
the superposition of the various venous systems makes the interpretation of the standard vertebral phlebogram difficult (Fig. 3). This technique was useful especially for the study of the midline venous systems. The anterior pontomesencephalic vein, the precentral cerebellar vein, the superior and inferior vermian veins, and their interlaminar tributaries were seen selectively, usually on the midline section of the posterior fossa. This makes the outlines of the interpeduncular fossa, of the ventral surface of the pons, and of the vermis clearly visible. Besides, the evaluation of the median sagittal diameter of the mesencephalon and of the pons was easier and more exact, because the section chosen to measure these diameters corresponded to the median sagittal plane of the posterior fossa (Fig. 4 c). Usually, a detailed study of the internal occipital veins, of the thalamic veins, of the pineal veins, of the posterior and lateral mesencephalic veins, of the superior and inferior retrotonsillar veins was obtained from the paramedian sections (Fig. 4a, b, d), while more lateral sections were used to study the cerebellar hemispheric veins (Fig. 4 e, f). On the coronal tomographic sections the vessels of the vertebrobasilar system, which showed a prevailing sagittal course, were generally seen in short segments or in cross section. Exceptions to this are the basilar artery, the prepeduncular portion of the posterior cerebral arteries and the prepontine portion of the superior cerebellar arteries and sometimes the anterior inferior cerebellar arteries which, running in a rather long course on the same tomographic plane, were seen in rather long portions. The precise identification of the portion of the an-
terior inferior cerebellar artery, situated at the level of the petrus bone apex, and of the intracanalicular portion of the internal auditory artery which follows the inferior wall of the internal auditory canal, was particularly interesting. The observation of these vascular and skeletal structures on the same plane permitted us to evaluate their reciprocal spatial relations exactly (Fig. 5b, c). Coronal angiotomography in the phlebogram has provided most interesting findings in the study of the precentral cerebellar vein (Fig. 6) by eliminating the vascular superpositions which often make the identification of this vein difficult, and sometimes even impossible. This finding is very important since the precentral cerebellar vein represents, as it is well known, the ideal landmark for the midline of the posterior fossa. This technique, moreover, made the detailed study of the other veins of the posterior fossa, and especially of those of the pontocerebellar angle, possible. In fact, it was possible to obtain better systematization of the tributaries of the petrosal vein and a more exact evaluation of the relations between this vein and the apex of the petrus bone. Coronal angiotomography has contributed substantially to the precise identification of the upper and lower limits of the posterior fossa, indicated respectively by the tentorial veins and the occipital bone, seen on the same section. Angiotomography, carried out during the capillary phase, sometimes demonstrated in section the pulvinar, the cuneus, the cerebellum, the cerebeUar tonsils and part of the 4th ventricle; the last may be seen as a negative image in the general picture of the opacified surrounding parenchymal structures.
M. Rosa: Angiotomographic Study of the Normal Cerebral Circulation II Conclusions
Simultaneous tomography applied to normal vertebral angiography has made a substantial contribution to complete the evaluating criteria of the standard angiographic picture, because it has made possible: the observation of the vessels of the vertebrobasilar system on different planes at a constant and known distance, and therefore a spatial evaluation of such vessels; the evaluation of the skeletal and vascular structures on the same tomographic plane carrying out a selective study by eliminating those structures situated outside this plane; a better delimitation, and sometimes a direct observation of anatomical structures above and below the tentorium, and their spatial localization.
References
1. Cabanis, E.A., Calabro', A., Bonneville, J.F., Metzger, J., Ernest, C.: Angiotomographie. Trait6 de Radiodiagnostic, tome XIV-1. Paris: Masson 1975 2. Calabro', A.: Communication personnelle au IX6me Congr~sde Radiologie de Culture Latine. Venise, Octobre 1974 3. Du Boulay, G.M., Jackson, D.C.: Cranial angiotomography. Clin. Radiol. 16, 148-153 (1965) 4. Gerhard, P.: Tomography of the vertebro-basilar circulation. Roentgen Praxis 24, 49-53 (1971)
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5. Legre, J., Dufour, M., Debaene, A.: L'art6riographie vert6brale. Trait6 de Radiodiagnostic, tome XIII. Paris: Masson 1972 6. Oldenkott, P., Gerhardt, P.: Angiotomography of the posterior fossa. Neuroradiology 2, 212-215 (1971) 7. Poole, G.J., Kramer, R. A.: Posterior fossa midline venotomography. 9th Annual Meeting of the American Society of Neuroradiology, 1971 8. Ramella, G., Rosa, M.: Angiotomographic study of the normal cerebral circulation. Internal carotid artery system. Neuroradiology 8, 15-23 (1974) 9. Ramella, G., Rosa, M.: Angiotomography of the angiomas of the posterior fossa. Communication at X Symposium Neuroradiologicum. Punta del Este, march 1974. Acta radiol. in press 10. Rosa, M.: Angiotomographie c6r6brale: radio-anatomie normale. J. Radiol. Electrol. 56, 199 (1975) 11. Rosa, M., Ramella, G.: Angiotomographie de la circulation vertdbro-basilaire: anatomie normale. Communication au IX~me Congr6s de Radiologie de Culture Latine. Venise, Octobre 1974. J. Radiol. t~lectrol, in press 12. Viano, J., Metzger, J., Pertuiset, B.: L'angiotomographie c6r6brale. Rev. Neurol. 125, 155-164 (1971) 13. Wackenheim, A., Braun, J.P.: Angiography of the mesencephalon. Berlin, Heidelberg, New York: Springer 1970 14. Wackenheim, A., Nakayama, N., Wende, S.: Magnification of the veins in vertebral angiography. Neuroradiology 6, 56-59 (1973) Doc. Dr. Marco Rosa Radiological Dept. of St. Martino Hospital and Neurosurgical Clinic of the University Genoa, Italy.
