Neurnradiologg
Neuroradiology 11, 191-197 (1976)
@by Springer-Verlag 1976
Computer Tomography in the Diagnosis of Cerebellopontine Angle Tumours C. Gyldensted, J. Lester and J. Thomsen Departments of Neuroradiologyand ENT, Rigshospitalet,UniversityHospital Copenhagen, Denmark
Summary. 53 patients clinically suspected of having a cerebellopontine angle (CPA) lesion were examined by computer tomography (CT) with 160 × 160 matrix EMI scanner. 17 cases (32%) had tumour positive CT, of which 12 were neurinomas and 1 meningioma. 1 CT suggestive of a CPA lesion was false positive and 1 unoperated case is probably a false negative CT. Three of the eleven verified neurinomas (27%) were of the medial type originating in the angle cistern. One neurinoma protruding 1 cm into the cistern showed no contrast enhancement. 2 CT scans (3.8%) were unsatisfactory due to movements and the large size of the head. CT is valuable for the investigation of CPA pathology and the diagnostic efficiency compares favourably to other neuroradiological procedures. Key words: Computer tomography tumors - Cerebellopontine angle tumors
Acoustic
In the literature concerning CT only a total of 36 CPA lesions have been reported, all diagnosed with the 80 × 80 matrix EMI scanner [3, 4, 5, 7, 10, 11]. We have therefore found it of interest to publish our results with the 160 x 160 matrix EMI scanner in the investigation of CPA tumours and to compare CT with other procedures as petrous meatal tomography, opaque cisternography, vertebral angiography and pneumoencephalography. Paxton and Ambrose [11], in a rewiew of their first 650 CT scans, mentioned 11 CT positive angle lesions, 10 acoustic neurinomas and one glomus jugulare tumour, all with marked contrast enhancement following intravenous injection of 20 ml Conray 420. No details about tumour size are given, but they stressed the similarity on X-ray attenuation of tumour and normal brain tissue. Gawler et al. [3] mentioned two
cases of acoustic neurinomas seen by unenhanced CT. New et al. [10] reported of 7 acoustic neurinomas in a paper on 600 CT examinations. (80 × 80 matrix, 8 mm collimator used for posterior fossa). Four of the acoustic neurinomas had previously been operated upon, 2 cases were visible on plain CT scan. 2 neurinomas showed marked, and 3 others had moderate enhancement. They also mentioned the difficulty of examining CPAs with CT due to the dense irregular bony structures and mastoid air cells giving rise to computer "overswing". Tumour size in their material ranged from 1.5 to 3.0 cm. One large verified neurinoma showed no enhancement following 50 ml Hypaque 60. Kramer et al. [7] mention 7 CPA tumours, four of which could not be seen, and two more were identified only equivocally prior to intravenous infusion of 300 ml of methylglucamine diatrizoate 30. Greitz [4] has reported on 10 acoustic neurinomas among 361 CT scans made on suspicion of intracranial tumour, all 10 angle lesions were seen on PEG and only 6 on plain CT. 2 cases out of 3 were diagnosed on vertebral angiography. The attenuation of the neurinomas compared to normal brain was lower in 2 cases, in other 2 cases higher and in 6 equal to brain tissue. Hatam et al. [5] studied 4 of the above mentioned 10 neurinomas in an investigation of contrast enhancement with time, using Isopaque Cerebral in a dose corresponding to 1 ml/kg body weight. They found the attenuation of acoustic neurinomas to be very much like that of meningiomas with a precontrast value of 15-18 EMI units increasing to 27-32 units in the first scan obtained after the injection of contrast medium.
Material and Methods The material consisted of all patients referred to the neuroradiological department at Rigshospitalet for
192 CT scanning with a clinical working diagnosis of CPA tumour. A total of 53 cases were examined during the first 18 mounths after the installment of the EMI machine (September 1, 1974 - February 29, 1976). CT war performed with a 20 ° angulation between the scanning plane and the orbitometal line using a 13 mm collimator. 4 scanning sections before and immediately after intravenous injection of Isopaque Amin 280 were taken in the posterior fossa, the difference in height between the two scans being 7 ram. 2 scans at higher levels were made for visualization of the supratentorial structures. During the first 6 months we made 180 ° scans with a duration of 4.5 minutes and used contrast medium in doses corresponding to 1.0 ml/kg body weight, but during the last year the doses were raised to 1.5 ml/kg body weight and 225 ° scans have been performed in order to minimize the influence of patient movement. Measurements of tumour size on the polaroid pictures have been compared to cisternographic and operative findings. Analysis of attenuation values in both 160 × 160 and 80 × 80 paper prints was done in the verified cases. A tumour area of 16 pixels in the 8 0 / 8 0 print out, corresponding to a volume of 1.2 × 1.2 × 1.3 = 1.87 c m 3, w a s compared to the corresponding volume in the other CPA both before and after contrast injection. The diminution factor of our machine in the polaroid pictures is 3.3. Standard error of a water scan is 1.8 EMI units when operating at 120 KV, 33 mA and using a 13 mm collimator.
Results
The 53 patients (25F, 28M) had an average age of 50 years (range 17-78). Average duration of symptoms was 3.5 years (range 0.1-18). Details of the otoneurological findings and case stories are published in a separate paper [12]. No significant difference in age and duration of symptoms could be found between the 17 tumour cases and the 36 non-tumour patients in this material (Wilcoxon test, significance probability, P = 0.1). Mean age tumour cases: 52.3 years (range 32-70), mean age non-tumour cases: 50 years (range 17-78). Average duration of symptoms in tumour patients: 3.3 years (range 0.25-10). Average duration non-tumour cases: 4.0 years (range 0.1-20). The tumour material was broken down into 12 acoustic neurinomas and 4 non-neurinoma cases, but no significant difference was found between patient age in these two categories. Mean age non-neurinoma cases: 44.5 years (range 32-55). Mean age neurinoma cases: 53.5 years (range 32-67). P = 0.1). A difference in duration of symptoms was slightly possible
C. Gyldenstedet al.: ComputerTomographyof CPA Turnouts (0.05
Neuroradiology 11, 191-197 (1976)
@by Springer-Verlag 1976
Computer Tomography in the Diagnosis of Cerebellopontine Angle Tumours C. Gyldensted, J. Lester and J. Thomsen Departments of Neuroradiologyand ENT, Rigshospitalet,UniversityHospital Copenhagen, Denmark
Summary. 53 patients clinically suspected of having a cerebellopontine angle (CPA) lesion were examined by computer tomography (CT) with 160 × 160 matrix EMI scanner. 17 cases (32%) had tumour positive CT, of which 12 were neurinomas and 1 meningioma. 1 CT suggestive of a CPA lesion was false positive and 1 unoperated case is probably a false negative CT. Three of the eleven verified neurinomas (27%) were of the medial type originating in the angle cistern. One neurinoma protruding 1 cm into the cistern showed no contrast enhancement. 2 CT scans (3.8%) were unsatisfactory due to movements and the large size of the head. CT is valuable for the investigation of CPA pathology and the diagnostic efficiency compares favourably to other neuroradiological procedures. Key words: Computer tomography tumors - Cerebellopontine angle tumors
Acoustic
In the literature concerning CT only a total of 36 CPA lesions have been reported, all diagnosed with the 80 × 80 matrix EMI scanner [3, 4, 5, 7, 10, 11]. We have therefore found it of interest to publish our results with the 160 x 160 matrix EMI scanner in the investigation of CPA tumours and to compare CT with other procedures as petrous meatal tomography, opaque cisternography, vertebral angiography and pneumoencephalography. Paxton and Ambrose [11], in a rewiew of their first 650 CT scans, mentioned 11 CT positive angle lesions, 10 acoustic neurinomas and one glomus jugulare tumour, all with marked contrast enhancement following intravenous injection of 20 ml Conray 420. No details about tumour size are given, but they stressed the similarity on X-ray attenuation of tumour and normal brain tissue. Gawler et al. [3] mentioned two
cases of acoustic neurinomas seen by unenhanced CT. New et al. [10] reported of 7 acoustic neurinomas in a paper on 600 CT examinations. (80 × 80 matrix, 8 mm collimator used for posterior fossa). Four of the acoustic neurinomas had previously been operated upon, 2 cases were visible on plain CT scan. 2 neurinomas showed marked, and 3 others had moderate enhancement. They also mentioned the difficulty of examining CPAs with CT due to the dense irregular bony structures and mastoid air cells giving rise to computer "overswing". Tumour size in their material ranged from 1.5 to 3.0 cm. One large verified neurinoma showed no enhancement following 50 ml Hypaque 60. Kramer et al. [7] mention 7 CPA tumours, four of which could not be seen, and two more were identified only equivocally prior to intravenous infusion of 300 ml of methylglucamine diatrizoate 30. Greitz [4] has reported on 10 acoustic neurinomas among 361 CT scans made on suspicion of intracranial tumour, all 10 angle lesions were seen on PEG and only 6 on plain CT. 2 cases out of 3 were diagnosed on vertebral angiography. The attenuation of the neurinomas compared to normal brain was lower in 2 cases, in other 2 cases higher and in 6 equal to brain tissue. Hatam et al. [5] studied 4 of the above mentioned 10 neurinomas in an investigation of contrast enhancement with time, using Isopaque Cerebral in a dose corresponding to 1 ml/kg body weight. They found the attenuation of acoustic neurinomas to be very much like that of meningiomas with a precontrast value of 15-18 EMI units increasing to 27-32 units in the first scan obtained after the injection of contrast medium.
Material and Methods The material consisted of all patients referred to the neuroradiological department at Rigshospitalet for
192 CT scanning with a clinical working diagnosis of CPA tumour. A total of 53 cases were examined during the first 18 mounths after the installment of the EMI machine (September 1, 1974 - February 29, 1976). CT war performed with a 20 ° angulation between the scanning plane and the orbitometal line using a 13 mm collimator. 4 scanning sections before and immediately after intravenous injection of Isopaque Amin 280 were taken in the posterior fossa, the difference in height between the two scans being 7 ram. 2 scans at higher levels were made for visualization of the supratentorial structures. During the first 6 months we made 180 ° scans with a duration of 4.5 minutes and used contrast medium in doses corresponding to 1.0 ml/kg body weight, but during the last year the doses were raised to 1.5 ml/kg body weight and 225 ° scans have been performed in order to minimize the influence of patient movement. Measurements of tumour size on the polaroid pictures have been compared to cisternographic and operative findings. Analysis of attenuation values in both 160 × 160 and 80 × 80 paper prints was done in the verified cases. A tumour area of 16 pixels in the 8 0 / 8 0 print out, corresponding to a volume of 1.2 × 1.2 × 1.3 = 1.87 c m 3, w a s compared to the corresponding volume in the other CPA both before and after contrast injection. The diminution factor of our machine in the polaroid pictures is 3.3. Standard error of a water scan is 1.8 EMI units when operating at 120 KV, 33 mA and using a 13 mm collimator.
Results
The 53 patients (25F, 28M) had an average age of 50 years (range 17-78). Average duration of symptoms was 3.5 years (range 0.1-18). Details of the otoneurological findings and case stories are published in a separate paper [12]. No significant difference in age and duration of symptoms could be found between the 17 tumour cases and the 36 non-tumour patients in this material (Wilcoxon test, significance probability, P = 0.1). Mean age tumour cases: 52.3 years (range 32-70), mean age non-tumour cases: 50 years (range 17-78). Average duration of symptoms in tumour patients: 3.3 years (range 0.25-10). Average duration non-tumour cases: 4.0 years (range 0.1-20). The tumour material was broken down into 12 acoustic neurinomas and 4 non-neurinoma cases, but no significant difference was found between patient age in these two categories. Mean age non-neurinoma cases: 44.5 years (range 32-55). Mean age neurinoma cases: 53.5 years (range 32-67). P = 0.1). A difference in duration of symptoms was slightly possible
C. Gyldenstedet al.: ComputerTomographyof CPA Turnouts (0.05
