we retrospectively reviewed the initial mr images , obtained at our institution between january 1990 and january 2001 , of 61 patients [ m : f=39:22 ; age at presentation , 1 - 70 ( mean , 29.1 ) years ] with proven primary ependymoma . for mr examinations , 0.5- , 1.0- , or 1.5-t units , produced by various manufacturers , were employed . images were usually obtained using axial t2-weighted conventional or fast spin - echo sequences ( tr / te=4000/98 ) and sagittal t1-weighted sequences ( tr / te=450/10 ) . sixty patients underwent enhanced spin - echo t1-weighted imaging in the axial and sagittal planes after the injection of 0.1 mmol / kg gadopentetate dimeglumine ( magnevist ; schering , berlin , germany ) . tumor location was categorized as supratentorial , infratentorial , or spinal , the last of these being subcategorized as cervical , thoracic , or filar . if a tumor extended across two or more regions , it was classified according to the site of its greatest mass . at each location , supratentorial ependymomas were classed as transependymal if they arose within the ventricular system but breached the ependymal lining to invade surrounding parenchyma , or as intraventricular or intraparenchynal . infratentorial tumors were either intraventricular , or were associated with extension from the fourth ventricle through the foramen of magendie or luschka . a spinal tumor was considered central if axial imaging showed that no more than 60% of its cross - sectional area was located to one side of the midline , or eccentric if this was not the case ( 5 ) . the size of an intracranial lesion was determined according to its longest diameter , and for a spinal location , according to the number of spinal segments involved . for each imaging sequences , the signal intensity of an intracranial and a spinal tumor was compared , respectively , with that of gray matter and spinal cord . a tumor was considered to have a cystic component if a cyst associated with it contained an enhanced nodule or had an enhanced wall . especially in spinal cord ependymomas , this type of tumor is in contradistinction to the nonenhanced , non - neoplastic rostral and caudal reactive cysts often associated with spinal cord tumors . the distinction between rostral /caudal cysts and reactive dilatation of the central canal can be difficult , and secondary reactive dilatation of this kind was classified as a cyst ( 6 ) . if areas of high signal intensity were obscured at non - enhanced t1-weighted imaging , intratumoral hemorrhage was thought to be present . in ependymomas of the spinal cord , the presence or absence of a low signal intensity rim at the boundaries of the tumor at t2-weighted imaging , which suggested marginal hemorrhaging , was also evaluated . peritumoral edema was scored as absent , mild ( affecting an area less than half that of the tumor ) , moderate ( affecting an area greater than half that of tumor , but not greater than that of the tumor itself ) , or marked ( affecting an area greater than that of the tumor ) . the presence and pattern of tumor enhancement and the definition of enhanced borders were assessed . the enhancement pattern was qualitatively evaluated as either homo- or heterogeneous , and enhanced margins as either sharply or poorly defined . of 61 ependymomas , seven ( 12% ) were supratentorial , 19 ( 31% ) were infratentorial , and 35 tumors ( 57% ) were spinal . most supratentorial ependymomas ( in six of seven patients ) occurred in adults between their third and fifth decade . ten infratentorial tumors ( 53% ) , on the other hand , developed during the first decade . spinal cord tumors were found among all age groups , with two - thirds occurring in these between their third and fifth decade . four ( 57% ) of seven patients with supratentorial tumors , 12 ( 63% ) of 19 with infratentorial tumors , and 23 ( 66% ) of 35 with spinal cord tumors were male . of seven supratentorial ependymomas , one was entirely intraventricular , four were entirely intraparenchymal ( fig . 3 ) , and 12 ( 63% ) into the cerebellopontine angle through the lateral recesses and the foramen of luschka . ten extended both caudally and laterally via both the foramina of magendie and luschka ( fig . of 35 spinal cord tumors , 14 ( 40% ) were cervical , 10 ( 29% ) were thoracic , and 11 ( 31% ) were filar in location . transaxial images showed that the epicenters of 32 ( 91% ) of these 35 tumors corresponded to the center of the spinal cord . the longest diameter of supratentorial tumors ranged from 2.5 to 6.0 ( mean , 4.5 ) cm ; for intraparenchymal and intraventricular tumors , respectively , this measurement was 5.0 and 3.8 cm . infratentorial tumors ranged in size from 3.0 to 7.0 ( mean , 4.9 ) cm , and the extent of spinal cord tumors , measured along their neuraxis , was 1 - 13 ( mean , 3.1 ) vertebral segments . at ti - weighted imaging , three ( 43% ) of seven supratentorial tumors were isointense relative to gray matter , and three others ( 43% ) were hypointense ( fig . 2b ) ; 11 ( 58% ) of 19 infratentorial tumors and 22 ( 63% ) of 35 spinal cord tumors were isointense . at t2-weighted imaging , six ( 96% ) of seven supratentorial , 17 ( 89% ) of 19 infratentorial and 33 ( 94% ) of 35 spinal cord tumors were hyperintense relative to the signal intensity of gray matter . five ( 71% ) of seven supratentorial , 14 ( 74% ) of 19 infratentorial , and five ( 14% ) of 35 spinal cord ependymomas had an intratumoral cystic component ( fig . 1 ) , and in 17 ( 49% ) of 35 spinal cord tumors , rostral ( n=16 ) and/or caudal ( n=14 ) reactive cysts were present . among the 14 cervical cord tumors , cyst type was rostral ( n=9 ) , 5 ) , while the ten thoracic cord tumors contained either rostral ( n=5 ) , caudal ( n=3 ) , or both types of cyst ( n=3 ) . the cysts associated with the 11 filar tumors were either rostral ( n=2 ) , caudal ( n=1 ) or of both types ( n=1 ) . intratumoral hemorrhage occurred in 13 ( 21% ) of the 61 ependymomas [ in four ( 57% ) of seven supratentorial , six ( 32% ) of 19 infratentorial , and three ( 9% ) of 35 spinal cord tumors ] ( figs . 1 and 4 ) . at t2-weighted imaging , rim(s ) of low signal intensity , suggesting marginal hemorrhage between normal and tumor tissue , were seen at the upper or lower margins of six ( 17% ) of 35 spinal cord ependymomas ; four of the six were cervical ( fig . peritumoral edema occurred in four ( 57% ) of seven supratentorial , three ( 16% ) of 19 infratentorial , and eight ( 23% ) of 35 spinal cord tumors . among supratentorial tumors the edema was mild in two cases ( fig . 1 ) , moderate in one , and severe in one , three ( 75% ) of four intraparenchymal supratentorial tumors showed no or mild edema . in all three infratentorial tumors the edema was mild , and among spinal cord tumors it was mild in six and moderate in two ( fig . tumor enhancement was demonstrated in 56 patients ( 93% ) ; in 53 ( 95% ) of these ( five of six supratentorial , 18 of 19 infratentorial , 30 of 31 spinal cord tumors ) , the enhanced margins were sharply defined . enhancement was heterogeneous in five ( 71% ) of seven supratentorial tumors and 18 ( 95% ) of 19 infratentorial tumors ( fig . 2c ) , while among 34 spinal cord tumors , the observed pattern was homogeneous in 17 cases ( 50% ) ( fig . 5 ) and heterogeneous in 14 ( 41% ) ( fig . 6 ) . in three cases ( 9% ) the mr imaging findings of ependymomas for each location and spinal tumors for each subtype are summarized in tables 2 and 3 , respectively . most supratentorial ependymomas ( in six of seven patients ) occurred in adults between their third and fifth decade . ten infratentorial tumors ( 53% ) , on the other hand , developed during the first decade . spinal cord tumors were found among all age groups , with two - thirds occurring in these between their third and fifth decade . four ( 57% ) of seven patients with supratentorial tumors , 12 ( 63% ) of 19 with infratentorial tumors , and 23 ( 66% ) of 35 with spinal cord tumors were male . of seven supratentorial ependymomas , one was entirely intraventricular , four were entirely intraparenchymal ( fig . 3 ) , and 12 ( 63% ) into the cerebellopontine angle through the lateral recesses and the foramen of luschka . ten extended both caudally and laterally via both the foramina of magendie and luschka ( fig . of 35 spinal cord tumors , 14 ( 40% ) were cervical , 10 ( 29% ) were thoracic , and 11 ( 31% ) were filar in location . transaxial images showed that the epicenters of 32 ( 91% ) of these 35 tumors corresponded to the center of the spinal cord . the longest diameter of supratentorial tumors ranged from 2.5 to 6.0 ( mean , 4.5 ) cm ; for intraparenchymal and intraventricular tumors , respectively , this measurement was 5.0 and 3.8 cm . infratentorial tumors ranged in size from 3.0 to 7.0 ( mean , 4.9 ) cm , and the extent of spinal cord tumors , measured along their neuraxis , was 1 - 13 ( mean , 3.1 ) vertebral segments . at ti - weighted imaging , three ( 43% ) of seven supratentorial tumors were isointense relative to gray matter , and three others ( 43% ) were hypointense ( fig . 2b ) ; 11 ( 58% ) of 19 infratentorial tumors and 22 ( 63% ) of 35 spinal cord tumors were isointense . at t2-weighted imaging , six ( 96% ) of seven supratentorial , 17 ( 89% ) of 19 infratentorial and 33 ( 94% ) of 35 spinal cord tumors were hyperintense relative to the signal intensity of gray matter . five ( 71% ) of seven supratentorial , 14 ( 74% ) of 19 infratentorial , and five ( 14% ) of 35 spinal cord ependymomas had an intratumoral cystic component ( fig . 1 ) , and in 17 ( 49% ) of 35 spinal cord tumors , rostral ( n=16 ) and/or caudal ( n=14 ) reactive cysts were present . among the 14 cervical cord tumors , cyst type was rostral ( n=9 ) , 5 ) , while the ten thoracic cord tumors contained either rostral ( n=5 ) , caudal ( n=3 ) , or both types of cyst ( n=3 ) . the cysts associated with the 11 filar tumors were either rostral ( n=2 ) , caudal ( n=1 ) or of both types ( n=1 ) . intratumoral hemorrhage occurred in 13 ( 21% ) of the 61 ependymomas [ in four ( 57% ) of seven supratentorial , six ( 32% ) of 19 infratentorial , and three ( 9% ) of 35 spinal cord tumors ] ( figs . 1 and 4 ) . at t2-weighted imaging , rim(s ) of low signal intensity , suggesting marginal hemorrhage between normal and tumor tissue , were seen at the upper or lower margins of six ( 17% ) of 35 spinal cord ependymomas ; four of the six were cervical ( fig . peritumoral edema occurred in four ( 57% ) of seven supratentorial , three ( 16% ) of 19 infratentorial , and eight ( 23% ) of 35 spinal cord tumors . among supratentorial tumors the edema was mild in two cases ( fig . 1 ) , moderate in one , and severe in one , three ( 75% ) of four intraparenchymal supratentorial tumors showed no or mild edema . in all three infratentorial tumors the edema was mild , and among spinal cord tumors it was mild in six and moderate in two ( fig . among the 60 patients who underwent contrast - enhanced scanning , tumor enhancement was demonstrated in 56 patients ( 93% ) ; in 53 ( 95% ) of these ( five of six supratentorial , 18 of 19 infratentorial , 30 of 31 spinal cord tumors ) , the enhanced margins were sharply defined . enhancement was heterogeneous in five ( 71% ) of seven supratentorial tumors and 18 ( 95% ) of 19 infratentorial tumors ( fig . 2c ) , while among 34 spinal cord tumors , the observed pattern was homogeneous in 17 cases ( 50% ) ( fig . 5 ) and heterogeneous in 14 ( 41% ) ( fig . 6 ) . in three cases ( 9% ) the mr imaging findings of ependymomas for each location and spinal tumors for each subtype are summarized in tables 2 and 3 , respectively . ependymomas develop most often in children , adolescents and young adults , but may also occur in older age groups ( 3 ) . in our series , most supratentorial ependymomas developed during the third to fifth decade , while approximately 50% of infratentorial ependymomas occurred during the first decade . spinal cord tumors occurred between the first and seventh decade , with approximately two - thirds developing between the third and fifth . although no significant difference in the frequency of ependymomas between the two genders has been reported ( 7 ) , in our series they occurred 1.8 times more frequently in males than in females . although ependymomas are classically considered to occur most frequently in the fourth ventricle - infratentorial region ( 8) , the most common location in our series was the spinal cord ( 57% of 60 lesions ) , followed by infratentorial and then supratentorial . of all intracranial ependymomas , approximately 60% are infratentorial and 40% are supratentorial ( 9 ) , though in our series , the ratio was approximately 7:3 . whereas supratentorial tumors tend to be parenchymal , infratentorial tumors are usually intraventricular ( 10 ) , and we observed similar findings . the extraventricular location of most supratentorial ependymomas has been attributed to their origin in extraventricular ependymal cell rests ( 11 ) , which are reported to occur mainly in regions where subependymal neural glia extend into adjacent white matter , e.g. at the angled margins of the ventricles ( 12 ) . all four supratentorial intraparenchymal tumors in our series were large ( average diameter , 5.0 cm ) , and focally abutted the adjacent ventricle . " desmoplastic development " is the term used to describe the way in which infratentorial ependymomas extend through the outlet foramina of the fourth ventricle into the subarachnoid space of the posterior cranial fossa . the prevalence of desmoplastic development through the foramen of magendie and/or luschka in our study was similar to that previously reported ( 13 ) . the signal intensity of ependymomas is nonspecific . in our study , regardless of their location within the neuraxis , they were hypo- to isointense to gray matter at non - enhanced t1-weighted imaging , and hyperintense at t2-weighted imaging , findings which were similar to those of other cns tumors ( 14 , 15 ) . supratentorial ependymomas are commonly cystic ( between 40 and 85% ) ( 10 - 12 , 16 ) , and in our series , 71% ( 5/7 ) , including all that were supratentorial , had cystic components . our results confirm the observation of furie and provenzale ( 17 ) , who reported that supratentorial extraventricular ependymomas are typically large cystic masses . ( 13 ) reported that mr imaging depicted cystic change in 65% of such cases ; in our series , 74% ( 14/19 ) had cystic components . in contrast to intracranial ependymomas , these of the spinal cord are not usually cystic ( between 4 and 50% ) ( 5 , 18 ) ; in our series , only 14% ( 5/35 ) had an intratumoral cystic component . rostral and/or caudal cysts are frequently associated with intramedullary tumors of all histologic types ( 19 ) . these cysts are important because they reflect a reactive process within the spinal cord , do not contain neoplastic cells , and do not need to be resected ( 19 ) . however , the prevalence of associated reactive cysts does not serve as a distinguishing feature of ependymomas : epstein et al . ( 20 ) reported that about 30% of tumors were associated with a rostral or caudal cyst similar to that noted in spinal cord astrocytoma cases . intratumoral hemorrhage occurs infrequently in ependymomas , with a prevalence of 0 to 13% in three reported series ( 5 , 10 , 21 ) . in ours , the figure was slightly higher ( 21% ) , with regional variation ( highest in supratentorial tumors , 57% ; lowest in spinal cord tumors , 9% ) . at t2 imaging , the presence of a low - signal rim along the rostral or caudal margin of a spinal cord tumor is a fairly specific indicator of ependymoma , and was found in 20% and 64% of cases in the series investigated , respectively , by fine et al . the rim is due to the presence of hemosiderin at the margin of the tumor , arising , presumably , from prior subclinical tumoral hemorrhage , and is often referred to as a ' hemosiderin cap ' . in our series , it was more frequently observed in cervical tumors ( 29% ) , a finding similar to that of fine et al . ( 5 ) , and one which may support the idea that motional differences in neural tissues that occur at the relatively sharp interface between a tumor and the spinal cord partly account for the higher prevalence of marginal hemorrhage in the cervical region ( 22 ) . where there is parenchymal involvement , peritumoral edema is usually mild . in our series , all infratentorial ependymomas , 94% of spinal cord ependymomas , and 71% of supratentorial ependymomas showed no or mild peritumoral edema . we believe that the relative lack of peritumoral edema in infratentorial and spinal tumors results from the space limitation imposed by their intraventricular or intraspinal location . most ependymomas in our series ( 93% ) showed contrast enhancement , though the pattern of this varied . it was heterogeneous in 71% of supratentorial and 95% of infratentorial ependymomas , but homogeneous in 50% of spinal cord tumors . ( 23 ) stated that spinal cord ependymomas generally show intense , homogeneous enhancement , while fine et al . ( 5 ) , on the other hand , reported heterogeneous enhancement in 65% ( 15/23 ) of such cases . in our study , five of 16 infratentorial ependymomas with caudal extension through the foramen of magendie had an unenhanced intraventricular portion , whereas the caudally extended portion showed relatively intense enhancement . the margin of the enhanced area was sharply defined in 95% ( 53/56 ) of our cases . ( 5 ) stated that this finding is a characteristic feature of spinal cord ependymoma and is analogous to the surgical and histopathologic observation of a generally well - defined interface between ependymomas and adjacent spinal cord . johnson et al . ( 24 ) , however , emphasized that in intracranial tumors , isolated tumor - cell infiltration may exist outside the margin of contrast enhancement . in summary , slightly more than half of the 61 ependymomas occurred in the spinal cord . the incidence of a cystic component was significantly higher in intracranial than in spinal ependymomas . a ' hemosiderin cap ' was seen in 17% ( 6/35 ) of spinal ependymomas , most commonly in cervical tumors ( 4/6 ) . most ependymomas were accompanied by no or mild peritumoral edema , irrespective of their location . the observed pattern of contrast enhancement was more frequently heterogeneous in intracranial than in spinal ependymomas .
objectiveto compare the age distribution and characteristic mr imaging findings of ependymoma for each typical location within the neuraxis.materials and methodsduring a recent eleven - year period , mr images of 61 patients with histologically proven ependymomas were obtained and retrospectively reviewed in terms of incidence , peak age , location , size , signal intensity , the presence or absence of cyst and hemorrhage , enhancement pattern , and other associated findings.resultsamong the 61 patients , tumor location was spinal in 35 ( 57% ) , infrartentorial in 19 ( 31% ) , and supratentorial in seven ( 12% ) . in four of these seven , the tumor was located in brain parenchyma , and in most cases developed between the third and fifth decade . 
 approximately half of the infratentorial tumors occurred during the first decade . 
 the signal intensity of ependymomas was non - specific , regardless of their location . 
 a cystic component was seen in 71% ( 5/7 ) of supratentorial , 74% ( 14/19 ) of infratentorial , and 14% ( 5/35 ) of spinal cord tumors . 
 forty - nine percent ( 17/35 ) of those in the spinal cord were associated with rostral and/or caudal reactive cysts . 
 intratumoral hemorrhage occurred in 57% ( 4/7 ) of supratentorial , 32% ( 6/19 ) of infratentorial , and 9% ( 3/35 ) of spinal cord tumors . in 17% ( 6/35 ) of spinal ependymomas , a curvilinear low t2 signal , suggesting marginal hemorrhage , was seen at the upper and/or lower margins of the tumors . 
 peritumoral edema occurred in 57% ( 4/7 ) of supratentorial , 16% ( 3/19 ) of infratentorial and 23% ( 8/35 ) of spinal cord tumors . 
 seventy - two percent ( 5/7 ) of supratentorial and 95% ( 18/19 ) of infratentorial tumors showed heterogeneous enhancement , while in 50% ( 17/34 ) of spinal cord tumors , enhancement was homogeneous.conclusioneven though the mr imaging findings of ependymomas vary and are nonspecific , awareness of these findings , and of tumor distribution according to age , is helpful and increases the likelihood of correct preoperative clinical diagnosis .