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Neuroradiology 16,284-286 (1978)
@ by Springer-Verlag1978
Giant Aneurysms in CT and Angiography M. Nadjmi, M. Ratzka, and M. Wodarz Department of Neuroradiology,Universityof Wiirzburg,Wiirzburg,FRG
Summary. Giant intracranial aneurysms are frequently observed as incidental fmdings on CT and angiograms obtained for purposes other than subarachnoid hemorrhage, such as slowly evolving nerve palsy or hemiparesis. Since giant aneurysms often thrombose, the CT scan may demonstrate a larger aneurysmal volume than the angiogram. This paper presents CT and angiogram findings in cerebral aneurysms with a diameter of 25 m m 60 ram. The discussion covers: sort of aneurysm (congenital, arteriosclerotic); type and degree of thrombosis; long-term results after spontaneous thrombosis; and CT examination after using epsflon-aminocaproic acid.
Table 1. Age, localization, and maximum diameter of six giant aneurysms 'Case Age Iz~calization 1
67
2
64
3
75
4 5 6
49 41 44
M~mum diame~r(mm)
carotid artery, infraclinoidal carotid artery, infraclinoidal carotid artery, infraclinoidal middlecerebral artery basilarartery basilarartery
45 37 26 45 26 75
Table 2. Mean values and standard deviation (SD) of aneurysmsa in the plain scan We have examined six giant aneurysms both in CT and by angiography. These are: three infraclinoidal aneurysms of the internal carotid artery, one aneurysm of the middle cerebral artery up to the bifurcation of the carotid artery, one aneurysm at the place of bifurcation of the basilar artery (Case 5), and f'mally one aneurysm of the basflar artery itself. One patient (Case 1) was examined with EMI 1000, the rest with EMI 1010. The diameter of the aneurysms at the widest place was between 26 and 75 mm (Table 1). The maximum density in the noncontrast scan differed considerably and showed variations between 51 and 66 Hounsfield units, which were conditioned by the anatomic.pathologic alterations of the vessel wall including the thromboses. The calcifications, which occur relatively often in giant aneurysms, have not been taken into consideration here. These variations in density, however, are less when well-defined solid and homogenous aneurysm parts are compared with one another. Table 2 shows the average values in the noncontrast scan and their standard deviations. After the intravenous injection of 1 ml Conray/kg body weight the contrast density increased between 7 and 29 HU. It is primarily the degree of the development of the thrombosis and thereby the flow capacity of the
Case
Mean values
sD
1b 2 3 4 5 6
44.7 36.2 45.0 34.0 44.7
3.6 5.4 4.8 5.6 4.7
a Solid portions, calcified areas excluded b Could not be measured for technical reasons aneurysm with blood containing contrast medium that is responsible for this difference. Other errors arise because we used intravenous injections instead of infusions with contrast medium.
Examples A giant aneurysm of the internal carotid artery, infraclinoidal (Case 1), with erosion of the basal bone structures including petrous pyramids (Fig. 1). The aneurysm
0028-3940/78/0016/0284/$01.00
M. Nadjmi et al.: Giant Aneurysms in CT and Angiography
285
Fig. 1. Right giant aneurysm of carotid artery, infraclinoidal in CT and angiogram. Left noncontrast scan, right after injection of contrast medium (Case 1)
Fig. 3. Giant aneurysm of basilar artery with maximal diameter of 75 mm in CT and angiogram. Left nonconstrast scan, right after intervenous injection of contrast medium. In the angiogram the basilar artery is moved toward dorsal direction. A wide vessel area at the distal section of basilar artery has suggested an aneurysm which is not visible itself
Fig. 2. Right giant aneurysm of middle cerebral artery in CT and angiogram. Left noneontrast scan, right after intervenous injection of contrast medium (Case 4)
had caused paralysis o f the cerebral nerves II to VIII in the patient. No ligature o f the internal carotid artery was made because o f the advanced age of the patient. Nevertheless the neurologic symptoms including the exophthalmos slowly diminished during the 3 years o f observation. The CT checks showed an increase, albeit slight, in the density o f the aneurysm in the noncontrast scan. The increase was conditioned by the increasing development o f thrombosis. Case 2 showed another infraclinoidal aneurysm o f the internal carotid artery in the medial section of the carotid channel. Clinically this patient had only an isolated abducens paresis. A carotid ligature was not made here either. A third giant aneurysm with a maximum diameter of 26 mm (Case 3) was localized at this point. Whereas there was no danger of a rupture in the sense of subarachnoidal bleeding with all of these infraclinoidal aneurysms, the situation with the remaining three giant aneurysms was different. Case 4 showed a giant aneurysm of the medial cerebral artery (Fig. 2); direct intervention was refused by our neurosurgeons. Therapy with epsilon.aminocaproic acid was suggested, a treat-
286 merit which i~ sometimes tried with giant aneurysms. In the contrast scan~ the beginning of thrombosis development at the edges can indeed be seen, but there is also a distinct jincrease in.the size of the aneurysm. In addition, a massive cerebral edema has developed with displacement of the median structures including the ventricle system. With this treatment there occurred a distinct clinical deterioration with intracranial pressure and hemiparesis. A number of factors could be responsible for this. A disturbance o f the microcirculation can be considered as one of the causes of the cerebral edema, if one assumes that this therapy causes an acceleration of the blood coagulation in the free vessels as well. Case 4 is also particularly suitable for defining the density of the flowing blood, because the aneurysm in the noncontrast CT is very homogenous and shows no degenerative wall alterations. The average value of the aneurysm was 45.0 HU and was thus about 9 units higher than the density of the basal ganglia on the opposite side in the same patient. Here the average value of the basal ganglia was 36.6 HU (Table 2). As with all our other patients CT was carried out on this patient before the angiography. The suspected diagnosis of aneurysm had only been made with one patient; the other five patients had symptoms which were interpreted in the sense of a brain tumor of predominantly basal localization.
M. Nadjmi et al.: Giant Aneurysms in CT and Angiography Finally, despite CT and angiography, a false diagnosis was made with one patient, that of a clivus chordoma under the influence of the long development of the clinical picture with paralysis of the cerebral nerves (Fig. 3). The X-ray picture showed destruction of the clivus and of the dorsum sellae with paramedian calcification, which often occurs with clivus chordoma. In the angiogram the basilar artery was displaced from the clivus and was moved in a dorsal direction. A wide vessel area at the distal basilar section, which could have suggested an aneurysm, was interpreted as an ectasia of the basilar artery caused by chronic stoppage. We learned that it was an aneurysm from the neurosurgeons who, unsuspecting, wanted to perform a biopsy. This aneurysm had a maximum diameter of 75 ram, and in the CT it showed, by extreme differences in density, all the anatomic pathologic alterations of giant aneurysms, including thromboses and calcification.
M. Nadjmi, MD Department of Neuroradiology University of Wiirzburg Josef-Schneider-Str.11 D-8700 Wikzburg, FRG
Neuroradiology 16,284-286 (1978)
@ by Springer-Verlag1978
Giant Aneurysms in CT and Angiography M. Nadjmi, M. Ratzka, and M. Wodarz Department of Neuroradiology,Universityof Wiirzburg,Wiirzburg,FRG
Summary. Giant intracranial aneurysms are frequently observed as incidental fmdings on CT and angiograms obtained for purposes other than subarachnoid hemorrhage, such as slowly evolving nerve palsy or hemiparesis. Since giant aneurysms often thrombose, the CT scan may demonstrate a larger aneurysmal volume than the angiogram. This paper presents CT and angiogram findings in cerebral aneurysms with a diameter of 25 m m 60 ram. The discussion covers: sort of aneurysm (congenital, arteriosclerotic); type and degree of thrombosis; long-term results after spontaneous thrombosis; and CT examination after using epsflon-aminocaproic acid.
Table 1. Age, localization, and maximum diameter of six giant aneurysms 'Case Age Iz~calization 1
67
2
64
3
75
4 5 6
49 41 44
M~mum diame~r(mm)
carotid artery, infraclinoidal carotid artery, infraclinoidal carotid artery, infraclinoidal middlecerebral artery basilarartery basilarartery
45 37 26 45 26 75
Table 2. Mean values and standard deviation (SD) of aneurysmsa in the plain scan We have examined six giant aneurysms both in CT and by angiography. These are: three infraclinoidal aneurysms of the internal carotid artery, one aneurysm of the middle cerebral artery up to the bifurcation of the carotid artery, one aneurysm at the place of bifurcation of the basilar artery (Case 5), and f'mally one aneurysm of the basflar artery itself. One patient (Case 1) was examined with EMI 1000, the rest with EMI 1010. The diameter of the aneurysms at the widest place was between 26 and 75 mm (Table 1). The maximum density in the noncontrast scan differed considerably and showed variations between 51 and 66 Hounsfield units, which were conditioned by the anatomic.pathologic alterations of the vessel wall including the thromboses. The calcifications, which occur relatively often in giant aneurysms, have not been taken into consideration here. These variations in density, however, are less when well-defined solid and homogenous aneurysm parts are compared with one another. Table 2 shows the average values in the noncontrast scan and their standard deviations. After the intravenous injection of 1 ml Conray/kg body weight the contrast density increased between 7 and 29 HU. It is primarily the degree of the development of the thrombosis and thereby the flow capacity of the
Case
Mean values
sD
1b 2 3 4 5 6
44.7 36.2 45.0 34.0 44.7
3.6 5.4 4.8 5.6 4.7
a Solid portions, calcified areas excluded b Could not be measured for technical reasons aneurysm with blood containing contrast medium that is responsible for this difference. Other errors arise because we used intravenous injections instead of infusions with contrast medium.
Examples A giant aneurysm of the internal carotid artery, infraclinoidal (Case 1), with erosion of the basal bone structures including petrous pyramids (Fig. 1). The aneurysm
0028-3940/78/0016/0284/$01.00
M. Nadjmi et al.: Giant Aneurysms in CT and Angiography
285
Fig. 1. Right giant aneurysm of carotid artery, infraclinoidal in CT and angiogram. Left noncontrast scan, right after injection of contrast medium (Case 1)
Fig. 3. Giant aneurysm of basilar artery with maximal diameter of 75 mm in CT and angiogram. Left nonconstrast scan, right after intervenous injection of contrast medium. In the angiogram the basilar artery is moved toward dorsal direction. A wide vessel area at the distal section of basilar artery has suggested an aneurysm which is not visible itself
Fig. 2. Right giant aneurysm of middle cerebral artery in CT and angiogram. Left noneontrast scan, right after intervenous injection of contrast medium (Case 4)
had caused paralysis o f the cerebral nerves II to VIII in the patient. No ligature o f the internal carotid artery was made because o f the advanced age of the patient. Nevertheless the neurologic symptoms including the exophthalmos slowly diminished during the 3 years o f observation. The CT checks showed an increase, albeit slight, in the density o f the aneurysm in the noncontrast scan. The increase was conditioned by the increasing development o f thrombosis. Case 2 showed another infraclinoidal aneurysm o f the internal carotid artery in the medial section of the carotid channel. Clinically this patient had only an isolated abducens paresis. A carotid ligature was not made here either. A third giant aneurysm with a maximum diameter of 26 mm (Case 3) was localized at this point. Whereas there was no danger of a rupture in the sense of subarachnoidal bleeding with all of these infraclinoidal aneurysms, the situation with the remaining three giant aneurysms was different. Case 4 showed a giant aneurysm of the medial cerebral artery (Fig. 2); direct intervention was refused by our neurosurgeons. Therapy with epsilon.aminocaproic acid was suggested, a treat-
286 merit which i~ sometimes tried with giant aneurysms. In the contrast scan~ the beginning of thrombosis development at the edges can indeed be seen, but there is also a distinct jincrease in.the size of the aneurysm. In addition, a massive cerebral edema has developed with displacement of the median structures including the ventricle system. With this treatment there occurred a distinct clinical deterioration with intracranial pressure and hemiparesis. A number of factors could be responsible for this. A disturbance o f the microcirculation can be considered as one of the causes of the cerebral edema, if one assumes that this therapy causes an acceleration of the blood coagulation in the free vessels as well. Case 4 is also particularly suitable for defining the density of the flowing blood, because the aneurysm in the noncontrast CT is very homogenous and shows no degenerative wall alterations. The average value of the aneurysm was 45.0 HU and was thus about 9 units higher than the density of the basal ganglia on the opposite side in the same patient. Here the average value of the basal ganglia was 36.6 HU (Table 2). As with all our other patients CT was carried out on this patient before the angiography. The suspected diagnosis of aneurysm had only been made with one patient; the other five patients had symptoms which were interpreted in the sense of a brain tumor of predominantly basal localization.
M. Nadjmi et al.: Giant Aneurysms in CT and Angiography Finally, despite CT and angiography, a false diagnosis was made with one patient, that of a clivus chordoma under the influence of the long development of the clinical picture with paralysis of the cerebral nerves (Fig. 3). The X-ray picture showed destruction of the clivus and of the dorsum sellae with paramedian calcification, which often occurs with clivus chordoma. In the angiogram the basilar artery was displaced from the clivus and was moved in a dorsal direction. A wide vessel area at the distal basilar section, which could have suggested an aneurysm, was interpreted as an ectasia of the basilar artery caused by chronic stoppage. We learned that it was an aneurysm from the neurosurgeons who, unsuspecting, wanted to perform a biopsy. This aneurysm had a maximum diameter of 75 ram, and in the CT it showed, by extreme differences in density, all the anatomic pathologic alterations of giant aneurysms, including thromboses and calcification.
M. Nadjmi, MD Department of Neuroradiology University of Wiirzburg Josef-Schneider-Str.11 D-8700 Wikzburg, FRG
