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Metrizamide spinal computed tomography following myelography
Computerized 0 Pergamon
0363-8235/80/0501-0117802.00/0
Tomography, Vol. 4, pp. 111 to 125 Press Ltd. 1980. Printed in the U.S.A.
METRIZAMIDE SPINAL COMPUTED TOMOGRAPHY FOLLOWING MYELOGRAPHY HOZUMIARII, MUTSUMASA TAKAHASHI,YOSHIHARUTAMAKAWA,MASAWKI SUZUKI and MASAAKISHINDO Department of Radiology, Akita University School of Medicine, 1-chome, Hondo, Akita 010, Japan (Receioed 11 May 1979; in revisedform
1 August 1979; receivedfir
publication 10 August 1979)
Abstract-Spinal computed tomography was performed following me&amide myelography in five cases of spinal lesions. A metrizamide computed tomogram with myelogram revealed the extent of spinal tumors and disk herniation more precisely than a myelogram alone. In addition, syrinx of syringomyelia was demonstrated by sequential metrizamide computed tomography. This technique will play an essential role in the diagnosis of various spinal lesions. Metrizamide computed tomography
Metrizamide myelography
Spinal lesions
INTRODUCTION Computed tomography (CT) provides considerable diagnostic information about various parts of the body. Yet good results have not been obtained in the diagnosis of spinal cord diseases since the location of the spinal cord within the narrow bony canal may produce artifacts. Di Chiro et al. have proposed computer assisted myelography with metrizamide [l] to overcome this disadvantage. But this technique has not yet been fully evaluated. Here we present our preliminary experience with metrizamide CT and discuss its role in the diagnosis of spinal cord diseases. We emphasize that more information can be obtained from this technique than previous reports have indicated and that CT following myelography frequently provides useful information.
MATERIALS
AND
METHOD
Five cases of spinal lesions, including spinal tumors, disk herniation and syringomyelia, were studied by an ACTA Scanner 0100 following metrizamide myelography. The level of CT examination was determined by metrizamide myelography under fluoroscopy. Myelography was performed after intrathecal injection of metrizamide via the lumbar route in the decubitus position. Metrizamide was moved to the level of the lesion under fluoroscopic control. The concentration of metrizamide varied from 170 to 300 mgI/ml and 5 to 16 ml was injected, depending upon the level of the lesion and presumed degree of block. CT was performed immediately after metrizamide myelography. In syringomyelia, CT was repeated immediately, and at intervals of 24 and 48 hr after myelography. CASE
REPORTS
Case 1
A 24 year old woman was referred to our department because of progressive weakness of the lower extremities. She had been well until 15 months earlier, when she noticed weakness in her legs. 4 months ago a lumbar puncture was performed elsewhere with an abnormal Queckenstedt test. A spinal cord tumor at the level of L4 was suspected clinically and an operation was performed with no demonstrable tumor. The patient was referred to our hospital. Plain films and tomograms of the lumbar spine demonstrated erosion in the posterior aspect of L, with erosion of the right pedicle. The interpedicular distance was widened at this level. A complete block was demonstrated at the level of LZ and subarachnoid space was compressed to the 117
118
HOZUMI ARIIet al
Fig. 1. Case 1. a. Metrizamide myelogram. AP view. Spinal subarachnoid space is blocked at L, by an extradural tumor. Pedicles of L1 are thin and interpedicular distance is increased. b. Metrizamide CT at L,. No metrizamide at this level. Erosion of the pedicle is more marked on the right, but erosion of the body is more marked on the left. c. Metrizamide CT at L2. Subarachnoid space is compressed to the right. No definite shift of spinal cord is seen.
right on metrizamide myelogram (Fig. la). CT showed erosion of the right pedicle and the body of L1 (Fig. lb). The erosion of the vertebral body was more marked in the left posterior portion. Metrizamide CT revealed the subarachnoid space to be shifted anteriorly and to the right at the level of L2 (Fig. lc). This finding suggested that the tumor had arisen from the left posterior extradural space. An operation was performed and the extradural neurinoma was removed.
Metrizamide spinal computed tomography following myelography
119
Case 2 A 63 year old man was referred to our department for irradiation of a left mediastinal tumor. He had been well until 2 months before, when he developed a cough and left anterior chest pain. Several days later weakness in the legs and gait disturbance developed. On admission, neurological examination disclosed paraplegia, anesthesia below the level of Ths, and loss of deep tendon reflexes of the lower extremities. The Queckenstedt test was abnormal on lumbar puncture. Plain chest revealed a left anterior mediastinal tumor with destruction of the pedicle of Ths on the right. Myelography was performed with metrizamide (170 mgI/ml, 14 ml). The findings of an extradural tumor were observed. The subarachnoid space was completely blocked at the level of The. There was compression and shift of the spinal cord and surrounding subarachnoid space anteriorly and to the left, suggesting an extradural tumor (Fig. 2a). CT clearly revealed displacement of the subarachnoid space to the left at the level of Th7 (Fig. 2b). Laminectomy was performed and an extradural malignant thymoma was extirpated. Case 3 A 53 year old man was admitted to our hospital because of back pain and epigastralgia. He had undergone a left lower lobectomy for bronchogenic carcinoma 2 years previously. 5 months before the present admission he had developed back pain which became progressively worse. Neurological examination disclosed tenderness in the territory of Th9 spinal nerve. Plain film revealed destruction of pedicles of Th9 and suggested metastasis from bronchogenic carcinoma. A total dose of 4000 rads was delivered to Th9 resulting in appreciable pain relief. However, paraplegia recently developed. Myelography was performed with metrizamide (270 mgI/ml, 7 ml). The spinal subarachnoid space was displaced anteriorly by a posteriorly located tumor, but there was no block at this level (Fig. 3a). CT demonstrated complete destruction of lamina, spinous process and pedicles with compression of the spinal cord and subarachnoid space from its posterior aspect (Fig. 3b). Case 4 A 42 year old woman was admitted because of progressive numbness of fingers and gait disturbance. She had been well until 4 months previously, when she noticed numbness of the 3rd, 4th and 5th fingers on the right. Numbness of the fingers recently became worse and the patient has developed a similar numbness on the left. 2 months before admission, gait disturbance developed. Numbness of fingers and gait disturbance became progessively worse until admission. On admission neurological examination disclosed hypesthesia of the fingers and the ulnar side of both arms. Her gait was waddling. Deep tendon reflexes were increased on both upper and lower extremities. Extensor plantar response was equivocal on the right and negative on the left. She developed urinary incontinence during admission. Plain film of the cervical spine disclosed no abnormalities. Myelography was performed with metrizamide (300 mgI/ml, 10 ml). A lateral view in the prone position revealed indentation at the level of C 4-5 and C5_-6, which was considered to be due to intervertebral disk herniation (Fig. 4, a & b). CT revealed narrowed and posteriorly displaced subarachnoid space at these levels. Displacement of the subarachnoid space is more marked on the right side (Fig. 4c) and correlated well with clinical symptoms. Traction of the spine was performed and gait disturbance improved. Case 5
A 53 year old woman was admitted because of weakness and sensory disturbance in both upper extremities. For the last 20 years the patient has had Raynaud’s phenomenon. 12 years ago, her left 2nd and 3rd fingers became necrosed and were amputated. 10 years previously she had noticed weakness of the upper extremities, especially on the left side. She has had hypesthesia of left upper extremity for 5 years. On admission neurological examination disclosed sensory dissociation in the upper extremities. Triceps and biceps tendon reflexes were diminished bilaterally, while deep tendon reflexes of lower extremities were increased. Extensor plantar response was observed bilaterally. She had
myelography. AP view in prone position. There is a complete block al Th, Fig. 2 Case 2. a. Me&amide tumor on the right. Spinal cord and subarachnoid space are compressed to the le:ft. b. by aL” extradural Metrizamide CT at Th,. Left anterior portion of the subarachnoid space is obliterated.
,_3. Case 3. a. Metrizamide myelography. AP view. Spinal subarachnoid space is narrowed at Th, and root sleeve is obliterated on the right. b. Metrizamide CT at Th,. Pedicles, lamina and spinous prc xess are completely destructed. Soft tissue density compresses the spinal subarachnoid space anteriorly
HOZUMIARIIet al.
Fig. 4. Case 4. a. Metrizamide myelography. AP view. The spinal cord is enlarged and subarachnoid space is narrowed at C5 and C6. Root sleeves at C& are obliterated on both sides. b. Metrizamide myelography. at C5_-6 is most marked. c. Lateral view. There are indentations at C3_-4r C.,_S and C&. The indentation Metrizamide CT at C&. Disk herniation is clearly visualized on the right.
Metrizamide
spinal computed
tomography
following
Fig. 5. Case 5. a. Metrizamide myelography. AP view. Diffuse swelling Metrizamide CT. The subarachnoid space is narrowed within the enlarged seen in the syrinx.c. CT 24 hr after myelography. Metrizamide
myelography
I23
of the cervical cord is seen. b. spinal canal. No metrizamide IS is seen in the syrinx.
difficulty in raising her arms. A lumbar puncture yielded no abnormal findings. Plain film of the cervical spine revealed increased interpedicular distances. Cervical myelography was performed with metrizamide (230 mgI/ml, 16 ml). Myelogram revealed swelling of cervical cord, suggesting syringomyelia or intramedullary tumor (Fig. 5a). CT immediately after myelography revealed diffuse cervical cord swelling (Fig. 5b). CT performed 24 hr after myelography disclosed a high density area in the cervical cord (Fig. 5~). This high density area was thought to represent syrinx filled with contrast medium. CT performed 48 hr after metrizamide injection demonstrated no high density area. A drainage of the syrinx was performed and the diagnosis was confirmed. DISCUSSION Metrizamide is non-ionic water soluble contrast medium, rarely provoking serious complications after intrathecal injection. Its usefulness in lumbar, thoracic and cervical myelography has been
HOZ~JMIAKII er ol
124
reported and the value has been established. Recently metrizamide is also applied to evaluate CSF dynamics and cisterns using CT [2,3,4]. Although CT has gained a wide-spread acceptance in diagnostic neuroradiology, its value in the diagnosis of spinal cord diseases has not been established [5,&T, 8,9]. Di Chiro reported computer assisted myelography with metrizamide and suggested the possibility that this examination will play a part in the diagnosis of spinal cord tumors [I]. Coin et al. applied computer assisted myelography to disk herniation [lo]. In our three cases of spinal tumors, tumor extension is clearly demonstrated on transaxial sections. In addition, as in cases 1 and 3, bony changes adjacent to tumors are visualized more clearly and precisely. In case 4 CT with metrizamide demonstrated that disk herniation was more marked on the right side although we could not see the laterality on myelograms. Therefore, CT after metrizamide myelography clearly offers some benefits in the surgical treatment of disk diseases. In our hands this technique has become an essential preoperative examination. In case 5, questionable syrinx on plain CT was confirmed by sequential CT with metrizamide. If CT had been performed only immediately after metrizamide injection, the syrinx could not have been visualized. It has been reported that metrizamide usually refluxes into the 4th ventricle after intrathecal injection [2]. Therefore, if the spinal central canal is enlarged or a cystic lesion is connected with the 4th ventricle, refluxing metrizamide in the syrinx can be visualized. CT must be repeated at an appropriate interval because it takes time for metrizamide to reach the syrinx. In our case, CT was performed immediately, 24 and 48 hr after the initial myelography, and refluxing metrizamide in the syrinx was seen on the 24 hr CT. In our experience of metrizamide CT, the 4th ventricle is usually visualized 2 hr after injection of metrizamide, therefore CT 6-12 hr after metrizamide injection may be more appropriate for visualizing the syrinx. Forbes et ~11.reported a case in which a syringe of syringomyelia was faintly opacified after intrathecal injection of metrizamide, but after 24 hr no metrizamide was seen in the syrinx [ll]. We presume that more frequent CT would have visualized a syrinx more clearly. In Di Chiro’s report, a definite low density area representing a syrinx was noted on plain CT in 5 of 18 cases clinically diagnosed as syringomyelia [S]. We believe that syringomyelia would be diagnosed with higher accuracy by CT with metrizamide. Gas meylography may not be necessary in some syringomyelia. Roberson et al. reported a case whose cerebella-pontine angle tumor was obscured on CT performed 2 hr after metrizamide injection due to high concentration [4]. We must keep in mind that high concentration of metrizamide will obliterate a minute lesion by the partial volume phcnomenon. Therefore, sequential CT is necessary to demonstrate small lesions. In conclusion, sequential CT with metrizamide will become an essential examination for the diagnosis of various spinal lesions. SUMMARY Metrizamide myelography is replacing oil myelography and gas myelography in some spinal lesions. After metrizamide myelography computed tomography of the spine can be performed with ease at the level of the lesion. Computed tomography with metrizamide demonstrated extension of spinal tumors and disk herniation more clearly than a metrizamide myelogram alone. Furthermore, syrinx of syringomyelia was demonstrated to good advantage by sequential computed tomography. This technique will become an essential examination in the diagnosis of various spinal lesions. REFERENCES 1. G. 2. 3. 4. 5. 6. 7.
Di Chiro and D. Schellinger, Computed tomography of spinal cord after lumbar intrathecal introduction of metrizamide (Computer assisted myelography), Radiology 120, 101-104 (1976). 6. P. Drayer, A. E. Rosenbaum and H. B. Higman, Cerebrospinal fluid imaging using serial metrizamide CT cisternography, NeuroradioEogy 13, 7-17 (1977). B. P. Drayer, A. E. Rosenbaum, J. S. Kennerdell, A. G. Robinson, W. 0. Bank and G. L. Deeb, Computed tomographic diagnosis of suprasellar masses by intrathecal enhancement, Radiology 123, 339-344 (1977). G. H. Roberson, J. M. Taveras, R. Tadmore, J. Kleefield and G. Ellis, Computed tomography in metrizamide cisternography---Importance of coronal and axial views, J. Compul. assist. Tomogr. 1, 241-245 (1977). G. Di Chiro, S. P. Axelbaum, D. Schellinger, H. L. Twigg and R. S. Ledley, Computerized axial tomography in syringomyelia, New Eng. J. Med. 292, 13-16 (1975). H. E. James and M. 018, Computed tomography in spinal dysraphism, J. Comput. ussisr. Tomogr. I, 391 -397 (1977). G. Di Chiro, J. L. Doppman and L. Wener. Computed tomography of spinal cord arteriovenous malformations, Radiology 123, 351-354 (1977).
Metrizamide
spinal computed
tomography
following
myelography
125
8. H. Nakagawa. Y. P. Huang, L. I. Malis and B. S. Wolf, Computed tomography of intraspinal and paraspinal neoplasms. J. Comput ussist. Tomogr. I, 377-390 (1977). 9. M. Takahashi, M. Shindo and Y. Tamakawa, CT of spine and spinal cord, Naika 41, 564571 (1978) (in Japanese). IO. C. G. Coin, Y.-S. Chan, V. Keranen and M. Pennink, Computer assisted myelography in disk disease, J. Comput. assist. Tomogr. 1, 398~-404 (1977). Il. W. St. C. Forbes and I. Isherwood, Computed tomography in syringomyelia and the associated Arnold-Chiari type I malformation. Neuroradiology 15, 73-78 (1978).
About the Author-Hozum ARII is a radiologist at the Akita University School of Medicine. He graduated from Kyoto Prefectural University of Medicine in 1974 and had a residency training of general internal medicine at the same school. He has joined the staff of radiology at Akita University since 1976. He has a special interest in computed tomography as well as in neuroradiology. About the Author-MunuMAsA TAKAHASHI received
his M.D. degree from Kyushu University School of Medicine in 1960. He received formal residency training in radiology at the University of Michigan from 1962 to 1965 and fellowship training in vascular radiology at Stanford University from 1965 to 1966, followed by a staff appointment at University of California at Los Angeles from 1966 to 1967. After teaching at Kyushu University School of Medicine from 1967 to 1972 he became Professor and Chairman of Radiology Department at the Akita University School of Medicine in 1972, He was a visiting Professor at UCLA for one year beginning December 1977. His major interest has been in neuroradiology and cardiovascular radiology. With the development of computed tomography he expanded his field of interest to this new area as well. He is certified by the American Board of Radiology and the Japanese Board of Radiology.
About the Author---YOsHIHARu TAMAKAWA is an assistant professor at Akita University School of Medicine .joining the staff of the University in 1972. He graduated from Iwate Medical and Dental College in 1964. followed by formal residency training at Iwate Medical and Dental College Hospital and at St. Luke‘s Hospital in Tokyo. He has been interested in pediatric radiology. vascular radiology, neuroradiology as well as computed tomography. He has contributed a great deal in these fields. He is certified by the Japanese Board of Radiology. About the Author-mMAsAYUKI SUZUKI graduated from Kanazawa University in 1975 and had a residency training in general radiology at the same school. After a 2 year training at Kanazawa University, he came to Akita University to have a special training in computed tomography and neuroradiology. His major interests are general diagnostic radiology as well as computed tomography. About the Author--MASAAKISHINM) is a radiologist
at the Akita University School of Medicine following graduation from the same school in 1976. He has been interested in ultrasound and cardiovascular radiology as well as computed tomography.
0363-8235/80/0501-0117802.00/0
Tomography, Vol. 4, pp. 111 to 125 Press Ltd. 1980. Printed in the U.S.A.
METRIZAMIDE SPINAL COMPUTED TOMOGRAPHY FOLLOWING MYELOGRAPHY HOZUMIARII, MUTSUMASA TAKAHASHI,YOSHIHARUTAMAKAWA,MASAWKI SUZUKI and MASAAKISHINDO Department of Radiology, Akita University School of Medicine, 1-chome, Hondo, Akita 010, Japan (Receioed 11 May 1979; in revisedform
1 August 1979; receivedfir
publication 10 August 1979)
Abstract-Spinal computed tomography was performed following me&amide myelography in five cases of spinal lesions. A metrizamide computed tomogram with myelogram revealed the extent of spinal tumors and disk herniation more precisely than a myelogram alone. In addition, syrinx of syringomyelia was demonstrated by sequential metrizamide computed tomography. This technique will play an essential role in the diagnosis of various spinal lesions. Metrizamide computed tomography
Metrizamide myelography
Spinal lesions
INTRODUCTION Computed tomography (CT) provides considerable diagnostic information about various parts of the body. Yet good results have not been obtained in the diagnosis of spinal cord diseases since the location of the spinal cord within the narrow bony canal may produce artifacts. Di Chiro et al. have proposed computer assisted myelography with metrizamide [l] to overcome this disadvantage. But this technique has not yet been fully evaluated. Here we present our preliminary experience with metrizamide CT and discuss its role in the diagnosis of spinal cord diseases. We emphasize that more information can be obtained from this technique than previous reports have indicated and that CT following myelography frequently provides useful information.
MATERIALS
AND
METHOD
Five cases of spinal lesions, including spinal tumors, disk herniation and syringomyelia, were studied by an ACTA Scanner 0100 following metrizamide myelography. The level of CT examination was determined by metrizamide myelography under fluoroscopy. Myelography was performed after intrathecal injection of metrizamide via the lumbar route in the decubitus position. Metrizamide was moved to the level of the lesion under fluoroscopic control. The concentration of metrizamide varied from 170 to 300 mgI/ml and 5 to 16 ml was injected, depending upon the level of the lesion and presumed degree of block. CT was performed immediately after metrizamide myelography. In syringomyelia, CT was repeated immediately, and at intervals of 24 and 48 hr after myelography. CASE
REPORTS
Case 1
A 24 year old woman was referred to our department because of progressive weakness of the lower extremities. She had been well until 15 months earlier, when she noticed weakness in her legs. 4 months ago a lumbar puncture was performed elsewhere with an abnormal Queckenstedt test. A spinal cord tumor at the level of L4 was suspected clinically and an operation was performed with no demonstrable tumor. The patient was referred to our hospital. Plain films and tomograms of the lumbar spine demonstrated erosion in the posterior aspect of L, with erosion of the right pedicle. The interpedicular distance was widened at this level. A complete block was demonstrated at the level of LZ and subarachnoid space was compressed to the 117
118
HOZUMI ARIIet al
Fig. 1. Case 1. a. Metrizamide myelogram. AP view. Spinal subarachnoid space is blocked at L, by an extradural tumor. Pedicles of L1 are thin and interpedicular distance is increased. b. Metrizamide CT at L,. No metrizamide at this level. Erosion of the pedicle is more marked on the right, but erosion of the body is more marked on the left. c. Metrizamide CT at L2. Subarachnoid space is compressed to the right. No definite shift of spinal cord is seen.
right on metrizamide myelogram (Fig. la). CT showed erosion of the right pedicle and the body of L1 (Fig. lb). The erosion of the vertebral body was more marked in the left posterior portion. Metrizamide CT revealed the subarachnoid space to be shifted anteriorly and to the right at the level of L2 (Fig. lc). This finding suggested that the tumor had arisen from the left posterior extradural space. An operation was performed and the extradural neurinoma was removed.
Metrizamide spinal computed tomography following myelography
119
Case 2 A 63 year old man was referred to our department for irradiation of a left mediastinal tumor. He had been well until 2 months before, when he developed a cough and left anterior chest pain. Several days later weakness in the legs and gait disturbance developed. On admission, neurological examination disclosed paraplegia, anesthesia below the level of Ths, and loss of deep tendon reflexes of the lower extremities. The Queckenstedt test was abnormal on lumbar puncture. Plain chest revealed a left anterior mediastinal tumor with destruction of the pedicle of Ths on the right. Myelography was performed with metrizamide (170 mgI/ml, 14 ml). The findings of an extradural tumor were observed. The subarachnoid space was completely blocked at the level of The. There was compression and shift of the spinal cord and surrounding subarachnoid space anteriorly and to the left, suggesting an extradural tumor (Fig. 2a). CT clearly revealed displacement of the subarachnoid space to the left at the level of Th7 (Fig. 2b). Laminectomy was performed and an extradural malignant thymoma was extirpated. Case 3 A 53 year old man was admitted to our hospital because of back pain and epigastralgia. He had undergone a left lower lobectomy for bronchogenic carcinoma 2 years previously. 5 months before the present admission he had developed back pain which became progressively worse. Neurological examination disclosed tenderness in the territory of Th9 spinal nerve. Plain film revealed destruction of pedicles of Th9 and suggested metastasis from bronchogenic carcinoma. A total dose of 4000 rads was delivered to Th9 resulting in appreciable pain relief. However, paraplegia recently developed. Myelography was performed with metrizamide (270 mgI/ml, 7 ml). The spinal subarachnoid space was displaced anteriorly by a posteriorly located tumor, but there was no block at this level (Fig. 3a). CT demonstrated complete destruction of lamina, spinous process and pedicles with compression of the spinal cord and subarachnoid space from its posterior aspect (Fig. 3b). Case 4 A 42 year old woman was admitted because of progressive numbness of fingers and gait disturbance. She had been well until 4 months previously, when she noticed numbness of the 3rd, 4th and 5th fingers on the right. Numbness of the fingers recently became worse and the patient has developed a similar numbness on the left. 2 months before admission, gait disturbance developed. Numbness of fingers and gait disturbance became progessively worse until admission. On admission neurological examination disclosed hypesthesia of the fingers and the ulnar side of both arms. Her gait was waddling. Deep tendon reflexes were increased on both upper and lower extremities. Extensor plantar response was equivocal on the right and negative on the left. She developed urinary incontinence during admission. Plain film of the cervical spine disclosed no abnormalities. Myelography was performed with metrizamide (300 mgI/ml, 10 ml). A lateral view in the prone position revealed indentation at the level of C 4-5 and C5_-6, which was considered to be due to intervertebral disk herniation (Fig. 4, a & b). CT revealed narrowed and posteriorly displaced subarachnoid space at these levels. Displacement of the subarachnoid space is more marked on the right side (Fig. 4c) and correlated well with clinical symptoms. Traction of the spine was performed and gait disturbance improved. Case 5
A 53 year old woman was admitted because of weakness and sensory disturbance in both upper extremities. For the last 20 years the patient has had Raynaud’s phenomenon. 12 years ago, her left 2nd and 3rd fingers became necrosed and were amputated. 10 years previously she had noticed weakness of the upper extremities, especially on the left side. She has had hypesthesia of left upper extremity for 5 years. On admission neurological examination disclosed sensory dissociation in the upper extremities. Triceps and biceps tendon reflexes were diminished bilaterally, while deep tendon reflexes of lower extremities were increased. Extensor plantar response was observed bilaterally. She had
myelography. AP view in prone position. There is a complete block al Th, Fig. 2 Case 2. a. Me&amide tumor on the right. Spinal cord and subarachnoid space are compressed to the le:ft. b. by aL” extradural Metrizamide CT at Th,. Left anterior portion of the subarachnoid space is obliterated.
,_3. Case 3. a. Metrizamide myelography. AP view. Spinal subarachnoid space is narrowed at Th, and root sleeve is obliterated on the right. b. Metrizamide CT at Th,. Pedicles, lamina and spinous prc xess are completely destructed. Soft tissue density compresses the spinal subarachnoid space anteriorly
HOZUMIARIIet al.
Fig. 4. Case 4. a. Metrizamide myelography. AP view. The spinal cord is enlarged and subarachnoid space is narrowed at C5 and C6. Root sleeves at C& are obliterated on both sides. b. Metrizamide myelography. at C5_-6 is most marked. c. Lateral view. There are indentations at C3_-4r C.,_S and C&. The indentation Metrizamide CT at C&. Disk herniation is clearly visualized on the right.
Metrizamide
spinal computed
tomography
following
Fig. 5. Case 5. a. Metrizamide myelography. AP view. Diffuse swelling Metrizamide CT. The subarachnoid space is narrowed within the enlarged seen in the syrinx.c. CT 24 hr after myelography. Metrizamide
myelography
I23
of the cervical cord is seen. b. spinal canal. No metrizamide IS is seen in the syrinx.
difficulty in raising her arms. A lumbar puncture yielded no abnormal findings. Plain film of the cervical spine revealed increased interpedicular distances. Cervical myelography was performed with metrizamide (230 mgI/ml, 16 ml). Myelogram revealed swelling of cervical cord, suggesting syringomyelia or intramedullary tumor (Fig. 5a). CT immediately after myelography revealed diffuse cervical cord swelling (Fig. 5b). CT performed 24 hr after myelography disclosed a high density area in the cervical cord (Fig. 5~). This high density area was thought to represent syrinx filled with contrast medium. CT performed 48 hr after metrizamide injection demonstrated no high density area. A drainage of the syrinx was performed and the diagnosis was confirmed. DISCUSSION Metrizamide is non-ionic water soluble contrast medium, rarely provoking serious complications after intrathecal injection. Its usefulness in lumbar, thoracic and cervical myelography has been
HOZ~JMIAKII er ol
124
reported and the value has been established. Recently metrizamide is also applied to evaluate CSF dynamics and cisterns using CT [2,3,4]. Although CT has gained a wide-spread acceptance in diagnostic neuroradiology, its value in the diagnosis of spinal cord diseases has not been established [5,&T, 8,9]. Di Chiro reported computer assisted myelography with metrizamide and suggested the possibility that this examination will play a part in the diagnosis of spinal cord tumors [I]. Coin et al. applied computer assisted myelography to disk herniation [lo]. In our three cases of spinal tumors, tumor extension is clearly demonstrated on transaxial sections. In addition, as in cases 1 and 3, bony changes adjacent to tumors are visualized more clearly and precisely. In case 4 CT with metrizamide demonstrated that disk herniation was more marked on the right side although we could not see the laterality on myelograms. Therefore, CT after metrizamide myelography clearly offers some benefits in the surgical treatment of disk diseases. In our hands this technique has become an essential preoperative examination. In case 5, questionable syrinx on plain CT was confirmed by sequential CT with metrizamide. If CT had been performed only immediately after metrizamide injection, the syrinx could not have been visualized. It has been reported that metrizamide usually refluxes into the 4th ventricle after intrathecal injection [2]. Therefore, if the spinal central canal is enlarged or a cystic lesion is connected with the 4th ventricle, refluxing metrizamide in the syrinx can be visualized. CT must be repeated at an appropriate interval because it takes time for metrizamide to reach the syrinx. In our case, CT was performed immediately, 24 and 48 hr after the initial myelography, and refluxing metrizamide in the syrinx was seen on the 24 hr CT. In our experience of metrizamide CT, the 4th ventricle is usually visualized 2 hr after injection of metrizamide, therefore CT 6-12 hr after metrizamide injection may be more appropriate for visualizing the syrinx. Forbes et ~11.reported a case in which a syringe of syringomyelia was faintly opacified after intrathecal injection of metrizamide, but after 24 hr no metrizamide was seen in the syrinx [ll]. We presume that more frequent CT would have visualized a syrinx more clearly. In Di Chiro’s report, a definite low density area representing a syrinx was noted on plain CT in 5 of 18 cases clinically diagnosed as syringomyelia [S]. We believe that syringomyelia would be diagnosed with higher accuracy by CT with metrizamide. Gas meylography may not be necessary in some syringomyelia. Roberson et al. reported a case whose cerebella-pontine angle tumor was obscured on CT performed 2 hr after metrizamide injection due to high concentration [4]. We must keep in mind that high concentration of metrizamide will obliterate a minute lesion by the partial volume phcnomenon. Therefore, sequential CT is necessary to demonstrate small lesions. In conclusion, sequential CT with metrizamide will become an essential examination for the diagnosis of various spinal lesions. SUMMARY Metrizamide myelography is replacing oil myelography and gas myelography in some spinal lesions. After metrizamide myelography computed tomography of the spine can be performed with ease at the level of the lesion. Computed tomography with metrizamide demonstrated extension of spinal tumors and disk herniation more clearly than a metrizamide myelogram alone. Furthermore, syrinx of syringomyelia was demonstrated to good advantage by sequential computed tomography. This technique will become an essential examination in the diagnosis of various spinal lesions. REFERENCES 1. G. 2. 3. 4. 5. 6. 7.
Di Chiro and D. Schellinger, Computed tomography of spinal cord after lumbar intrathecal introduction of metrizamide (Computer assisted myelography), Radiology 120, 101-104 (1976). 6. P. Drayer, A. E. Rosenbaum and H. B. Higman, Cerebrospinal fluid imaging using serial metrizamide CT cisternography, NeuroradioEogy 13, 7-17 (1977). B. P. Drayer, A. E. Rosenbaum, J. S. Kennerdell, A. G. Robinson, W. 0. Bank and G. L. Deeb, Computed tomographic diagnosis of suprasellar masses by intrathecal enhancement, Radiology 123, 339-344 (1977). G. H. Roberson, J. M. Taveras, R. Tadmore, J. Kleefield and G. Ellis, Computed tomography in metrizamide cisternography---Importance of coronal and axial views, J. Compul. assist. Tomogr. 1, 241-245 (1977). G. Di Chiro, S. P. Axelbaum, D. Schellinger, H. L. Twigg and R. S. Ledley, Computerized axial tomography in syringomyelia, New Eng. J. Med. 292, 13-16 (1975). H. E. James and M. 018, Computed tomography in spinal dysraphism, J. Comput. ussisr. Tomogr. I, 391 -397 (1977). G. Di Chiro, J. L. Doppman and L. Wener. Computed tomography of spinal cord arteriovenous malformations, Radiology 123, 351-354 (1977).
Metrizamide
spinal computed
tomography
following
myelography
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About the Author-Hozum ARII is a radiologist at the Akita University School of Medicine. He graduated from Kyoto Prefectural University of Medicine in 1974 and had a residency training of general internal medicine at the same school. He has joined the staff of radiology at Akita University since 1976. He has a special interest in computed tomography as well as in neuroradiology. About the Author-MunuMAsA TAKAHASHI received
his M.D. degree from Kyushu University School of Medicine in 1960. He received formal residency training in radiology at the University of Michigan from 1962 to 1965 and fellowship training in vascular radiology at Stanford University from 1965 to 1966, followed by a staff appointment at University of California at Los Angeles from 1966 to 1967. After teaching at Kyushu University School of Medicine from 1967 to 1972 he became Professor and Chairman of Radiology Department at the Akita University School of Medicine in 1972, He was a visiting Professor at UCLA for one year beginning December 1977. His major interest has been in neuroradiology and cardiovascular radiology. With the development of computed tomography he expanded his field of interest to this new area as well. He is certified by the American Board of Radiology and the Japanese Board of Radiology.
About the Author---YOsHIHARu TAMAKAWA is an assistant professor at Akita University School of Medicine .joining the staff of the University in 1972. He graduated from Iwate Medical and Dental College in 1964. followed by formal residency training at Iwate Medical and Dental College Hospital and at St. Luke‘s Hospital in Tokyo. He has been interested in pediatric radiology. vascular radiology, neuroradiology as well as computed tomography. He has contributed a great deal in these fields. He is certified by the Japanese Board of Radiology. About the Author-mMAsAYUKI SUZUKI graduated from Kanazawa University in 1975 and had a residency training in general radiology at the same school. After a 2 year training at Kanazawa University, he came to Akita University to have a special training in computed tomography and neuroradiology. His major interests are general diagnostic radiology as well as computed tomography. About the Author--MASAAKISHINM) is a radiologist
at the Akita University School of Medicine following graduation from the same school in 1976. He has been interested in ultrasound and cardiovascular radiology as well as computed tomography.