Nearnradiologv
Neuroradiology 16,199-202 (1978)
© by Springer-Verlag1978
Comparison of Metrizamide CT Cisternography with Radionuclide Cisternography in Abnormal Cerebrospinal Fluid Dynamics M. Takahashi, H. Arii, and Y. Tamakawa Department of Radiology, Akita University School of Medicine, Akita, Japan
Summary. Metrizamide CT cisternograms were performed on 39 patients with a clinical diagnosis of CSF abnormalities; 20 of these patients underwent radionuclide cisternography as well. Comparison of metrizamide CT and RN cisternography revealed good correlation in the degree, extent, and time sequence of ventricular reflux as well as the extent of cortical staining and cisternal Idling. Metrizamide cisternography had the advantage of excellent anatomic detail and lower exposure dose, although minor complications were more frequent with this technique. Metrizamide CT cisternography has a potential to become the preferred method of evaluating patients with abnormal CSF dynamics.
cluding normal pressure hydrocephalus (NPH) and tumors in the base of the brain. Among the 39 patients were 10 on whom metrizamide CT cisternogram can be considered normal on follow-up examination as well as on the basis of other neuroradiologic procedures. Metrizamide CT cisternograms of these 10 cases were used for analysis of normal studies. Twenty of the 39 patients underwent RN cisternography (Table 1). Seven of 20 patients who had both metrizamide CT cisternograms and RN cisternograms were finally considered to have normal pressure hydrocephalus. Additional patients had abnormal CSF dynamics; four patients had subarachnoid hemorrhage; two patients had meningoencephalitis; and one patient had a cerebellopontine angle tumor. The remaining seven patients had miscellaneous conditions with normal CSF dynamics. Shunt procedures were performed in six cases and proved to be effective in three patients (Table 1). With all these 39 cases together with 12 patients who underwent myelography using intrathecal metrizamide the side effects following intrathecal injection of metrizamide were evaluated.
Introduction
The establishment of the diagnosis of abnormal CSF dynamics remains a difficult task. There have been many frustrations in attempting to develop clinical or pneumoencephalographic criteria for the diagnosis of this problem [8, 9]. Radionuclide (RN) cisternography seemed most reliable but had its own frustrations, primarily relating to relatively poor resolution and technical failures [2]. When computed tomography (CT) became available, most neuroradiologists felt that our problem in distinguishing cerebral atrophy from changes related to abnormal CSF dynamics had been solved. However, it quickly became apparent that this was not the case [ 7 - 9 ] . During the recent clinical trials of metrizamide myelography, some experience was gained" with metrizamide CT cisternography [1, 2, 4 - 6 ] . The purpose of this study is to evaluate the results of this technique as compared to radionuclide cisternography. Materials Forty-five metrizamide cisternograms were performed on 39 patients with a clinical diagnosis of abnormal fluid dynamics in-
Methods
1. Metrizamide CT Cisternography Premedication of 5 to 10 mg of intramuscular diazepam was given to apprehensive patients or to patients with previous history of seizures. Lumbar intrathecal injection of 10 to 12 ml of metrizamide (170 mg I/ml) was made in the lateral recumbent position. The patient was then placed in the supine position on a table tilted 10 to 20 degrees Trendelenburg with the neck flexed on a large pillow under the head. This position was maintained until the first 2-h scan was started. Scans were performed at 2, 6, and 24 h after intrathecal injection of contrast media. Twelve- and 48-h scans were also obtained if necessary. An ACTA scanner 0100 was used with planes parallel to the orbitomeatal line [ 11.
2. R N Cisternography RN cisternograms were performed with lumbar intrathecal injection of 1 mCi of 169Yb-DTPAor lllIn-DTPA. RN cisternograms were obtained at time intervals comparable to those used with metrizamide CT cisternograms, utilizing a Pho/Gamma Camera (Nuclear-Chicago) with a parallel fine collimator.
0028-3940/78/0016/0199/$ 01.00
200
M. Takahashi et al.: Comparison of Metrizamide CT and RN Cisternography
Table 1. Case materials
Case Age Number
Table 2. Intraventricular
Table 3. Failure of cortical
reflux
blush and cisternal filling
Sex
Final diagnosis
Shunt procedure
Metrizamide CT cisternogram
RN cisternogram
Metrizamide CT cisternograms
RN eisternograms
++-I+++
+++ -t-F+
++
q-I-+
Convexity Parasagittal Convexity Parasagittal Parasagittal Convexity Paxasagittal Parasagittal Tentorial Tentorial Left tentorial Convexity Tentorial Parasagittal Left parasagittal Parasagittal
Parasagittal Parasagittal Convexity Parasagittal Parasagittal Convexity Parasagittal Parasagittal Tentorial Tentorial Convexity
None None None None None None
None None None None None None
1
62
F
65 56 66 67
M M M F
Normal pressure hydrocephalus Normal pressure hydrocephalus Normal pressure hydrocephalus Normal pressure hydrocephalus Normal pressure hydrocephalus
Not effective
2 3 4 5 6 7 8 9 10
55 52 30 29 66
M M M F F
Normal pressure hydrocephalus Normal pressure hydrocephalus Subarachnoid hemorrhage Subarachnoid hemorrhage Subarachnoid hemorrhage
Not effective
11 12 13
56 25 12
M F M
Subarachnoid hemorrhage Meningoencephalitis Meningoencephalitis
14
33
F
Left cerebellopontine angle
+++ +++
Effective Effective Effective
Not effective
++
+-I-, q-I-+
++
++
++
+++ + +++
+++ ++ +++
+++
+++
-I-k+ +++
+++ +++
+-H-
+++
+
+
+
+
Tentorial Parasagittal None Parasagittal
tumor
15 16 17 18 19 20
28 64 49 15 78 20
M M F F M M
Largecisterna magna Cerebellar ataxia Optic neuritis Cerebellar degeneration Cerebral atrophy Cerebral atrophy
3. Routine CT Scans Evaluation was made as to enlargement of the cortical sulci, sylvian fissure, and lateral ventricles. The enlargements were graded as (1) not enlarged, (2) minimal enlargement for patient's age (+), (3) moderate enlargement (++), and (4) marked enlargement (+++).
4. Comparison of Metrizamide CT Cisternograms and R N Cisternograms Metrizamide CT cisternograms and RN cisternograms were evaluated with special attention to reflux of the injected media into the lateral ventricles, and flow of the media to the cerebral cortex and cisterns. Ventricular reflux on metrizamide CT cisternograms and RN cisternograms was graded as (1) absence of ventricular reflux (-), (2) minimal increase of attenuation values or radioactivity of the lateral ventricle (+), (3) moderate reflux (++), and (4) marked reflux (+++).
5. Side Effects Development of side effects was carefully evaluated for 48 h following intrathecal injection of contrast media.
terns of the posterior fossa and the base of the brain together with visualization of the fourth ventricle and occasional filling of the posterior third ventricle. The 6-h CT scan showed filling of the sylvian fissure, interhemispheric fissure, and cerebral sulci. At this time, there was slight reflux of media in the lateral ventricle in four cases as evidenced by slight increase in CT numbers of the lateral ventricle, but the ventricular reflux had cleared on the 12-h scans. At 12 and 24 h, there was diffuse staining of the cerebral and cerebeUar cortex with minimal residue in the cisterns and cerebral sulci, and complete clearing from the ventricular system.
2. Remits of Routine CT Scans All the 14 patients with abnormal CSF dynamics had moderate to marked ventricular enlargement. Enlargement of the temporal horns was always observed. Cortical sulcal enlargement was seen in six cases, including moderate or marked enlargement in two. There was enlargement of the sylvian fissure in nine patients, five cases showing moderate to marked enlargement. Periventricular edema was observed in six cases.
Results
3. Abnormal Metrizamide CT Cisternogram 1. Normal MetrizamMe CT Cisternogram In individuals with normal CSF circulation, metrizamide CT cisternography at 2 h showed good Idling of the cis-
In patients with abnormal CSF dynamics, there was reflux of metrizamide into the ventricular system, beyond that seen in normal patients, at 6, 12, and 24 h. Poor f'fl-
M. Takahashi et al.: Comparison of Metrizamide CT and RN Cisternography
201
ling o f the sylvian fissure a n d / o r cerebral sulci was freq u e n t l y observed. Staining o f the c o r t e x was frequently p o o r or deficient.
4. Comparison o f Metrizamide CT Cisternograms and R N Cisternograms Comparison o f m e t r i z a m i d e CT and R N cisternography in patients w i t h abnormal and normal CSF dynamics demonstrated good correlation in the degree, extent, and time sequence o f ventricular reflux as well as p o o r or non-fiUing o f the subarachnoid spaces (Table 1, Figs. 1 and 2). Ventricular reflux and absence o f cisternal filling or cortical staining was d e m o n s t r a t e d better on metrizamide CT cisternograms than on RN cisternograms. Parti-
Fig. 1. Case 5. A 67-year-old female with normal pressure hydrocephalus, a. RN cisternogram (the number indicates hours after intrathecal injection). No filling of the parasagittal area and cerebral convexity is seen. There is moderate ventrieular reflux. b. Metrizarnide CT cisternogram at 6 h (left) and 24 h (right). There is marked ventrieular reflux. The sylvian fissure and interhemispheric fissure are well seen. There is no filling of cortical sulci or parasagittal area. Staining of the cortex is poor over the cerebral hemisphere, while good staining is seen at the sylvian and interhemispherie fissures. The lateral ventricle is not defined at 24 h
Fig. 2. Case 13. A 12-year-old male with meningoencephalitis. a. RN cisternogram. There is moderate reflux of radionuclides into the lateral ventricles. Parasagittal and convexity filling is poor. b. Metrizamide CT eisternogram at 6 h (left) and 24 h (right). There is marked ventriculax reflux of metrizamide bilaterally. The sylvian fissures on the right and cerebral sulci on the left are well shown with contrast, b u t the left sylvian fissure, right cerebral sulci, and interhemispheric fissure are not demonstrated
202
M. Takahashi et al.: Comparison of Metrizamide CT and RN Cisternography
cularly, minimal reflux was better evaluated on metrizamide CT cisternograms. A case with a cerebellopontine angle tumor revealed marked intraventricular reflux on metrizamide CT cisternograms and RN cisternograms. Cisternal and sulcal Filling was delayed. It was postulated that cisternal incomplete block was responsible for this finding.
5. Side Effects Headache and nausea were most common side effects, observed in 27.5% and 23.5% respectively. Vomiting was observed in 15.7% and vertigo in 7.8%. All the side effects appeared within 8 h and were relieved 12 to 24 h after intrathecal injection of contrast media. One patient developed unilateral hearing loss, but hearing returned to normal in 24 h. No change in vital signs was noted during the 48-h observation period nor were there any seizures in this group of 51 patients.
With metrizamide CT cisternography, there do exist inherent difficulties in interpretation. The exact diagnostic criteria are not yet established in cases with slow flow in the CSF space and minimal intraventricular reflux of contrast media. Drayer et al. classified these cases as intermediate CSF abnormality [2]. In our cases, similar findings were occasionally observed. It has been a dilemma whether or not to perform a shunt procedure in these patients. However, it is in these cases that accurate diagnostic information is essential.
Conclusion We feel that when metrizamide becomes widely available, CT cisternography may well become the preferred method of screening patients with suspected abnormal CSF dynamics. It is hoped that more accurate criteria for the diagnosis of NPH using metrizamide CT cisternography may be developed in the future.
Discussion References Diagnosis of NPH has been primarily based upon comprehensive neurologic evaluation and RN cisternography [8, 9]. However, there have been several recent reports which question the accuracy of RN cisternography as an important diagnostic technique for predicting the success of a shunting procedure [8, 9]. Recently, CT without use of metrizamide has been added to the diagnostic arma. mentarium of this condition [3]. This technique, as applied in patients with NPH, has been reported to show moderate hydrocephalus with poor visualization of cortical sulci and periventricular edema. A later report revealed that enlargement of cortical sulci may occasionally be observed in the presence of NPH [7]. Our results are in agreement with these reports. Symmetric hydrocephalus with periventricular edema without apparent cause may be the sole criteria of NPH on CT. Therefore, a technique to diagnose NPH with high accuracy has not been available. Use of metrizamide in CT for demonstration of CSF dynamics was first proposed by Greitz and Hindmarsh [4-6], followed by a comprehensive report by Drayer et al. [2]. These authors have demonstrated good correlation between metrizamide CT cisternography and RN cisternography on the basis of a limited number of cases. Our results, with a larger case material, are also in agreement with these authors. Furthermore, metrizamide CT cisternography appears to provide high resolution with good anatomic detail, which enables us to assess accurately the site and nature of the compromised CSF space. Further advantages of metrizamide CT cisternography include lower radiation exposure of the spine, easier handling of the material, and lower failure rate.
1. Arii, H., Takahashi, M., Tamakawa, Y., Odani, R., Nakano, Y., Suzuki, M., Shindo, M., Okazaki, M., Ohkubo, M.: Computed tomography with use of metrizamide. Nippon Acta Radiol. (in press 1978) 2. Drayer, B. P., Rosenbaum, A. E., Higman, H. B.: Cerebrospinal fluid imaging using serial metrizamide CT cisternography. Neuroradiology 13, 7-17 (1977) 3. Gado, M. H., Coleman, R. E., Lee, K. S., Mikhael, M. A., Alderson, P. O., Archer, C. R.: Correlation between computerized transaxial tomography and radionuclide cisternography in dementia. Neurology 26, 555-560 (1976) 4. Greitz, T., Hindmarsh, T.: Computer assisted tomography of intracranial CSF circulation using a water-soluble contrast medium. Acta Radiol. (Diagn.) 15,497-507 (1974) 5. Hindmarsh, T.: Elimination of water-soluble contrast media from the subarachnoid space. Acta Radiol. [Suppl.l 346, 4550 (1975) 6. Hindmarsh, T., Greitz, T.: Computer cisternography in the diagnosis of communicating hydrocephalus. Acta Radiol. (Diagn.) 346, 91-97 (1975) 7. Jacobs, L., Kinkel, W.: Computerized axial transverse tomography in normal pressure hydrocephalus. Neurology 26,501507 (1976) 8. Messert, B., Wannamaker, B. B.: Reappraisal of the adult occult hydrocephalus syndrome. Neurology 24, 224-231 (1974) 9. Wood, J. H., Bartlet, D., James, A. E., Jr., Udvarhelyi, G. B.: Normal-pressure hydrocephalus: Diagnosis and patient selection for shunt surgery. Neurology 24, 517-526 (1974)
M. Takahashi, MD Department of Radiology Akita University School of Medicine Akita, Japan
Neuroradiology 16,199-202 (1978)
© by Springer-Verlag1978
Comparison of Metrizamide CT Cisternography with Radionuclide Cisternography in Abnormal Cerebrospinal Fluid Dynamics M. Takahashi, H. Arii, and Y. Tamakawa Department of Radiology, Akita University School of Medicine, Akita, Japan
Summary. Metrizamide CT cisternograms were performed on 39 patients with a clinical diagnosis of CSF abnormalities; 20 of these patients underwent radionuclide cisternography as well. Comparison of metrizamide CT and RN cisternography revealed good correlation in the degree, extent, and time sequence of ventricular reflux as well as the extent of cortical staining and cisternal Idling. Metrizamide cisternography had the advantage of excellent anatomic detail and lower exposure dose, although minor complications were more frequent with this technique. Metrizamide CT cisternography has a potential to become the preferred method of evaluating patients with abnormal CSF dynamics.
cluding normal pressure hydrocephalus (NPH) and tumors in the base of the brain. Among the 39 patients were 10 on whom metrizamide CT cisternogram can be considered normal on follow-up examination as well as on the basis of other neuroradiologic procedures. Metrizamide CT cisternograms of these 10 cases were used for analysis of normal studies. Twenty of the 39 patients underwent RN cisternography (Table 1). Seven of 20 patients who had both metrizamide CT cisternograms and RN cisternograms were finally considered to have normal pressure hydrocephalus. Additional patients had abnormal CSF dynamics; four patients had subarachnoid hemorrhage; two patients had meningoencephalitis; and one patient had a cerebellopontine angle tumor. The remaining seven patients had miscellaneous conditions with normal CSF dynamics. Shunt procedures were performed in six cases and proved to be effective in three patients (Table 1). With all these 39 cases together with 12 patients who underwent myelography using intrathecal metrizamide the side effects following intrathecal injection of metrizamide were evaluated.
Introduction
The establishment of the diagnosis of abnormal CSF dynamics remains a difficult task. There have been many frustrations in attempting to develop clinical or pneumoencephalographic criteria for the diagnosis of this problem [8, 9]. Radionuclide (RN) cisternography seemed most reliable but had its own frustrations, primarily relating to relatively poor resolution and technical failures [2]. When computed tomography (CT) became available, most neuroradiologists felt that our problem in distinguishing cerebral atrophy from changes related to abnormal CSF dynamics had been solved. However, it quickly became apparent that this was not the case [ 7 - 9 ] . During the recent clinical trials of metrizamide myelography, some experience was gained" with metrizamide CT cisternography [1, 2, 4 - 6 ] . The purpose of this study is to evaluate the results of this technique as compared to radionuclide cisternography. Materials Forty-five metrizamide cisternograms were performed on 39 patients with a clinical diagnosis of abnormal fluid dynamics in-
Methods
1. Metrizamide CT Cisternography Premedication of 5 to 10 mg of intramuscular diazepam was given to apprehensive patients or to patients with previous history of seizures. Lumbar intrathecal injection of 10 to 12 ml of metrizamide (170 mg I/ml) was made in the lateral recumbent position. The patient was then placed in the supine position on a table tilted 10 to 20 degrees Trendelenburg with the neck flexed on a large pillow under the head. This position was maintained until the first 2-h scan was started. Scans were performed at 2, 6, and 24 h after intrathecal injection of contrast media. Twelve- and 48-h scans were also obtained if necessary. An ACTA scanner 0100 was used with planes parallel to the orbitomeatal line [ 11.
2. R N Cisternography RN cisternograms were performed with lumbar intrathecal injection of 1 mCi of 169Yb-DTPAor lllIn-DTPA. RN cisternograms were obtained at time intervals comparable to those used with metrizamide CT cisternograms, utilizing a Pho/Gamma Camera (Nuclear-Chicago) with a parallel fine collimator.
0028-3940/78/0016/0199/$ 01.00
200
M. Takahashi et al.: Comparison of Metrizamide CT and RN Cisternography
Table 1. Case materials
Case Age Number
Table 2. Intraventricular
Table 3. Failure of cortical
reflux
blush and cisternal filling
Sex
Final diagnosis
Shunt procedure
Metrizamide CT cisternogram
RN cisternogram
Metrizamide CT cisternograms
RN eisternograms
++-I+++
+++ -t-F+
++
q-I-+
Convexity Parasagittal Convexity Parasagittal Parasagittal Convexity Paxasagittal Parasagittal Tentorial Tentorial Left tentorial Convexity Tentorial Parasagittal Left parasagittal Parasagittal
Parasagittal Parasagittal Convexity Parasagittal Parasagittal Convexity Parasagittal Parasagittal Tentorial Tentorial Convexity
None None None None None None
None None None None None None
1
62
F
65 56 66 67
M M M F
Normal pressure hydrocephalus Normal pressure hydrocephalus Normal pressure hydrocephalus Normal pressure hydrocephalus Normal pressure hydrocephalus
Not effective
2 3 4 5 6 7 8 9 10
55 52 30 29 66
M M M F F
Normal pressure hydrocephalus Normal pressure hydrocephalus Subarachnoid hemorrhage Subarachnoid hemorrhage Subarachnoid hemorrhage
Not effective
11 12 13
56 25 12
M F M
Subarachnoid hemorrhage Meningoencephalitis Meningoencephalitis
14
33
F
Left cerebellopontine angle
+++ +++
Effective Effective Effective
Not effective
++
+-I-, q-I-+
++
++
++
+++ + +++
+++ ++ +++
+++
+++
-I-k+ +++
+++ +++
+-H-
+++
+
+
+
+
Tentorial Parasagittal None Parasagittal
tumor
15 16 17 18 19 20
28 64 49 15 78 20
M M F F M M
Largecisterna magna Cerebellar ataxia Optic neuritis Cerebellar degeneration Cerebral atrophy Cerebral atrophy
3. Routine CT Scans Evaluation was made as to enlargement of the cortical sulci, sylvian fissure, and lateral ventricles. The enlargements were graded as (1) not enlarged, (2) minimal enlargement for patient's age (+), (3) moderate enlargement (++), and (4) marked enlargement (+++).
4. Comparison of Metrizamide CT Cisternograms and R N Cisternograms Metrizamide CT cisternograms and RN cisternograms were evaluated with special attention to reflux of the injected media into the lateral ventricles, and flow of the media to the cerebral cortex and cisterns. Ventricular reflux on metrizamide CT cisternograms and RN cisternograms was graded as (1) absence of ventricular reflux (-), (2) minimal increase of attenuation values or radioactivity of the lateral ventricle (+), (3) moderate reflux (++), and (4) marked reflux (+++).
5. Side Effects Development of side effects was carefully evaluated for 48 h following intrathecal injection of contrast media.
terns of the posterior fossa and the base of the brain together with visualization of the fourth ventricle and occasional filling of the posterior third ventricle. The 6-h CT scan showed filling of the sylvian fissure, interhemispheric fissure, and cerebral sulci. At this time, there was slight reflux of media in the lateral ventricle in four cases as evidenced by slight increase in CT numbers of the lateral ventricle, but the ventricular reflux had cleared on the 12-h scans. At 12 and 24 h, there was diffuse staining of the cerebral and cerebeUar cortex with minimal residue in the cisterns and cerebral sulci, and complete clearing from the ventricular system.
2. Remits of Routine CT Scans All the 14 patients with abnormal CSF dynamics had moderate to marked ventricular enlargement. Enlargement of the temporal horns was always observed. Cortical sulcal enlargement was seen in six cases, including moderate or marked enlargement in two. There was enlargement of the sylvian fissure in nine patients, five cases showing moderate to marked enlargement. Periventricular edema was observed in six cases.
Results
3. Abnormal Metrizamide CT Cisternogram 1. Normal MetrizamMe CT Cisternogram In individuals with normal CSF circulation, metrizamide CT cisternography at 2 h showed good Idling of the cis-
In patients with abnormal CSF dynamics, there was reflux of metrizamide into the ventricular system, beyond that seen in normal patients, at 6, 12, and 24 h. Poor f'fl-
M. Takahashi et al.: Comparison of Metrizamide CT and RN Cisternography
201
ling o f the sylvian fissure a n d / o r cerebral sulci was freq u e n t l y observed. Staining o f the c o r t e x was frequently p o o r or deficient.
4. Comparison o f Metrizamide CT Cisternograms and R N Cisternograms Comparison o f m e t r i z a m i d e CT and R N cisternography in patients w i t h abnormal and normal CSF dynamics demonstrated good correlation in the degree, extent, and time sequence o f ventricular reflux as well as p o o r or non-fiUing o f the subarachnoid spaces (Table 1, Figs. 1 and 2). Ventricular reflux and absence o f cisternal filling or cortical staining was d e m o n s t r a t e d better on metrizamide CT cisternograms than on RN cisternograms. Parti-
Fig. 1. Case 5. A 67-year-old female with normal pressure hydrocephalus, a. RN cisternogram (the number indicates hours after intrathecal injection). No filling of the parasagittal area and cerebral convexity is seen. There is moderate ventrieular reflux. b. Metrizarnide CT cisternogram at 6 h (left) and 24 h (right). There is marked ventrieular reflux. The sylvian fissure and interhemispheric fissure are well seen. There is no filling of cortical sulci or parasagittal area. Staining of the cortex is poor over the cerebral hemisphere, while good staining is seen at the sylvian and interhemispherie fissures. The lateral ventricle is not defined at 24 h
Fig. 2. Case 13. A 12-year-old male with meningoencephalitis. a. RN cisternogram. There is moderate reflux of radionuclides into the lateral ventricles. Parasagittal and convexity filling is poor. b. Metrizamide CT eisternogram at 6 h (left) and 24 h (right). There is marked ventriculax reflux of metrizamide bilaterally. The sylvian fissures on the right and cerebral sulci on the left are well shown with contrast, b u t the left sylvian fissure, right cerebral sulci, and interhemispheric fissure are not demonstrated
202
M. Takahashi et al.: Comparison of Metrizamide CT and RN Cisternography
cularly, minimal reflux was better evaluated on metrizamide CT cisternograms. A case with a cerebellopontine angle tumor revealed marked intraventricular reflux on metrizamide CT cisternograms and RN cisternograms. Cisternal and sulcal Filling was delayed. It was postulated that cisternal incomplete block was responsible for this finding.
5. Side Effects Headache and nausea were most common side effects, observed in 27.5% and 23.5% respectively. Vomiting was observed in 15.7% and vertigo in 7.8%. All the side effects appeared within 8 h and were relieved 12 to 24 h after intrathecal injection of contrast media. One patient developed unilateral hearing loss, but hearing returned to normal in 24 h. No change in vital signs was noted during the 48-h observation period nor were there any seizures in this group of 51 patients.
With metrizamide CT cisternography, there do exist inherent difficulties in interpretation. The exact diagnostic criteria are not yet established in cases with slow flow in the CSF space and minimal intraventricular reflux of contrast media. Drayer et al. classified these cases as intermediate CSF abnormality [2]. In our cases, similar findings were occasionally observed. It has been a dilemma whether or not to perform a shunt procedure in these patients. However, it is in these cases that accurate diagnostic information is essential.
Conclusion We feel that when metrizamide becomes widely available, CT cisternography may well become the preferred method of screening patients with suspected abnormal CSF dynamics. It is hoped that more accurate criteria for the diagnosis of NPH using metrizamide CT cisternography may be developed in the future.
Discussion References Diagnosis of NPH has been primarily based upon comprehensive neurologic evaluation and RN cisternography [8, 9]. However, there have been several recent reports which question the accuracy of RN cisternography as an important diagnostic technique for predicting the success of a shunting procedure [8, 9]. Recently, CT without use of metrizamide has been added to the diagnostic arma. mentarium of this condition [3]. This technique, as applied in patients with NPH, has been reported to show moderate hydrocephalus with poor visualization of cortical sulci and periventricular edema. A later report revealed that enlargement of cortical sulci may occasionally be observed in the presence of NPH [7]. Our results are in agreement with these reports. Symmetric hydrocephalus with periventricular edema without apparent cause may be the sole criteria of NPH on CT. Therefore, a technique to diagnose NPH with high accuracy has not been available. Use of metrizamide in CT for demonstration of CSF dynamics was first proposed by Greitz and Hindmarsh [4-6], followed by a comprehensive report by Drayer et al. [2]. These authors have demonstrated good correlation between metrizamide CT cisternography and RN cisternography on the basis of a limited number of cases. Our results, with a larger case material, are also in agreement with these authors. Furthermore, metrizamide CT cisternography appears to provide high resolution with good anatomic detail, which enables us to assess accurately the site and nature of the compromised CSF space. Further advantages of metrizamide CT cisternography include lower radiation exposure of the spine, easier handling of the material, and lower failure rate.
1. Arii, H., Takahashi, M., Tamakawa, Y., Odani, R., Nakano, Y., Suzuki, M., Shindo, M., Okazaki, M., Ohkubo, M.: Computed tomography with use of metrizamide. Nippon Acta Radiol. (in press 1978) 2. Drayer, B. P., Rosenbaum, A. E., Higman, H. B.: Cerebrospinal fluid imaging using serial metrizamide CT cisternography. Neuroradiology 13, 7-17 (1977) 3. Gado, M. H., Coleman, R. E., Lee, K. S., Mikhael, M. A., Alderson, P. O., Archer, C. R.: Correlation between computerized transaxial tomography and radionuclide cisternography in dementia. Neurology 26, 555-560 (1976) 4. Greitz, T., Hindmarsh, T.: Computer assisted tomography of intracranial CSF circulation using a water-soluble contrast medium. Acta Radiol. (Diagn.) 15,497-507 (1974) 5. Hindmarsh, T.: Elimination of water-soluble contrast media from the subarachnoid space. Acta Radiol. [Suppl.l 346, 4550 (1975) 6. Hindmarsh, T., Greitz, T.: Computer cisternography in the diagnosis of communicating hydrocephalus. Acta Radiol. (Diagn.) 346, 91-97 (1975) 7. Jacobs, L., Kinkel, W.: Computerized axial transverse tomography in normal pressure hydrocephalus. Neurology 26,501507 (1976) 8. Messert, B., Wannamaker, B. B.: Reappraisal of the adult occult hydrocephalus syndrome. Neurology 24, 224-231 (1974) 9. Wood, J. H., Bartlet, D., James, A. E., Jr., Udvarhelyi, G. B.: Normal-pressure hydrocephalus: Diagnosis and patient selection for shunt surgery. Neurology 24, 517-526 (1974)
M. Takahashi, MD Department of Radiology Akita University School of Medicine Akita, Japan
