vascular pulsatile tinnitus ( pt ) is a perceived sound synchronous with the heartbeat without any external stimulus and is attributed to arterial and venous causes .
venous pt is more common than arterial pt and is caused by numerous vascular anomalies and variants ; surgical and endovascular interventions have proven successful for some lesions .
it is important to distinguish these anomalies or variants on imaging to determine the appropriate treatment strategy . thus far ,
previous studies on the incidence of these anomalies and variants of venous pt have notable limitations ; they used small sample sizes and did not include several recently described venous pt anomalies , such as a dehiscent sigmoid plate and petrosquamosal sinus .
in addition , a more effective technique ( dual - phase contrast - enhanced computed tomography [ dp - cect ] ) capable of detailing the vessels and temporal bones simultaneously has been gaining popularity for pt diagnosis , but it has not been investigated previously . therefore , additional research evaluating the incidence of vascular anomalies and variants in venous pt is needed .
previous studies have found that pt does not resolve completely or recur in select pt patients postoperatively .
it is speculated that treatment of only one anomaly may not work when more than one pt anomaly exists on a single side .
however , there are no studies indicating whether these venous pt anomalies and variants are multiple or single , which could significantly impact the prognosis of venous pt patients . therefore , we sought to identify the incidence of vascular anomalies and variants of venous pt by retrospectively reviewing the dp - cect images of 242 unilateral venous pt patients and determine whether these anomalies and variants occur as multiple or single lesions on the symptomatic side of each patient .
a total 242 venous pt patients ( 27 men , 215 women ; mean age 40.9 years ; age range 1169 years ) were enrolled in the current study between february 2010 and march 2013 .
the criteria for inclusion were as follows : ( 1 ) pt in one ear ; ( 2 ) the pt sound was persistent and synchronous with the heart beat ; and ( 3 ) pt resolved after compression of the internal jugular vein ipsilateral to the tinnitus and when turning the head to the pt side .
in addition , patients with arterial abnormalities , tumors involving the temporal bones , otosclerosis , and poor - quality images were excluded .
of the 242 patients , 156 patients had right - sided venous pt , and 86 patients had left - sided venous pt .
the mean duration of venous pt was 36.9 months ( range : 7 days to 36 years ) .
all patients underwent dp - cect scanning using a 64-slice multidetector ct ( brilliance 64 ; philips , best , the netherlands ) with the following parameters : 360 ma ; 100 kvp ; rotation time 0.75 s ; detector collimation 64 mm  0.625 mm ; pitch 0.89:1 ; field - of - view 22 cm  22 cm ; and matrix 512  512 .
the scanning range was from the vertex to the sixth cervical vertebrae . an iodinated nonionic contrast agent ( iopamidol [ 370 mg iodine / ml ] ; bracco , shanghai , china ) was administered intravenously at 5 ml / s using an electric power injector .
the contrast agent was dosed at 1.5 ml / kg according to the patient weight .
the arterial phase scan was trigged by the bolus - tracking program ( trigger bolus software ; philips , best , the netherlands ) after administering the contrast agent and performed in a cephalocaudal direction .
the ascending aorta served as the trigger point , and the trigger area was 200 mm .
the arterial phase scan time ranged 812 s. venous phase scanning was performed in the opposite direction after a fixed 8 s delay .
standard algorithms were used to reconstruct all arterial phase images , and standard and bone algorithms were used in all venous phase images .
multi - planar reconstruction images were generated on a workstation with a 1 mm slice thickness and no slice gap .
the axial images were reconstructed by setting the position baseline parallel to the bilateral lateral semicircular canals ; the coronal images were generated by setting the position baseline perpendicular to the bilateral lateral semicircular canals .
narrower settings ( width 700 hu ; level 200 hu ) were used to evaluate the arterial and venous systems , and bone window settings ( width 4000 hu ; level 700 hu ) were used to evaluate the sigmoid plates and temporal bones .
all ct images were individually evaluated by three radiologists with 5 , 6 , and 11 years of experience .
the vascular anomalies and variants on symptomatic and asymptomatic sides were analyzed and evaluated retrospectively .
these evaluated vascular anomalies and variants were diagnosed on the following previously described criteria [ figure 1 ] : ( 1 ) high jugular bulb , the jugular bulb extended above the inferior border of the round window ; ( 2 ) dehiscent jugular bulb or dehiscent sigmoid plate , the incomplete thin bone around the jugular bulb or the sigmoid sinus ; ( 3 ) jugular bulb diverticulum , prominent protrusion or an irregular out - pouching of jugular bulb that was clearly distinguished from a smooth ellipsoidal form ; ( 4 ) sigmoid sinus diverticulum , a diverticulum entered into the mastoid bone ; ( 5 ) lateral sinus stenosis , the l / s ratio ( l = the largest area of the vein ; s = the smallest area of the vein ) was > 4.75 ; ( 6 ) large emissary vein , diameter of the emissary veins was > 3.5 mm ; ( 7 ) petrosquamosal sinus , embryologic emissary vein running along the petrosquamosal fissure ; and ( 8) sinus thrombosis , signs of thrombosis were noted , including the empty -sign or an irregular filling defect .
various vascular anomalies and variants of venous pulsatile tinnitus detected on venous phase computed tomography ( ct ) images in this study .
axial ct image ; ( a ) sigmoid sinus diverticulum ( arrow ) accompanying with a dehiscent sigmoid plate ( arrowhead ) .
axial ct image ; ( b ) a stenosis in right transverse sinus ( arrow ) .
axial ct image ; ( c ) a high jugular bulb ( arrow ) and axial ct image ; ( d ) a right jugular bulb dehiscence ( arrow ) .
sagittal ct image ; ( f ) a petrosquamosal sinus running into the temporal bone ( arrow ) .
( g ) a filling defect ( thrombosis ) in the superior curve of right sigmoid sinus ( arrow ) .
the venous sinus systems were classified into three types based on standards proposed by krishnan et al .
co - dominant venous systems were identified when the diameters of the bilateral mid - transverse sinus differed by  3 mm .
right or left dominant venous systems were identified according to the side with the largest diameter .
all statistical tests were performed using statistical software ( spss , version 17.0 ; spss , chicago , il , usa ) .
the vascular anomalies and variants on symptomatic sides and asymptomatic sides were counted and summed .
the incidences of the anomalies and variants were compared on each side using the chi - square test or the fisher exact test .
in addition , number of findings on the symptomatic side in each patient was calculated to analyze the anomaly and variant diversification of venous pt .
spearman rank correlation test was used to evaluate the correlation between the side of pt and the side of dominant venous system .
a total 242 venous pt patients ( 27 men , 215 women ; mean age 40.9 years ; age range 1169 years ) were enrolled in the current study between february 2010 and march 2013 .
the criteria for inclusion were as follows : ( 1 ) pt in one ear ; ( 2 ) the pt sound was persistent and synchronous with the heart beat ; and ( 3 ) pt resolved after compression of the internal jugular vein ipsilateral to the tinnitus and when turning the head to the pt side .
in addition , patients with arterial abnormalities , tumors involving the temporal bones , otosclerosis , and poor - quality images were excluded .
of the 242 patients , 156 patients had right - sided venous pt , and 86 patients had left - sided venous pt .
the mean duration of venous pt was 36.9 months ( range : 7 days to 36 years ) .
all patients underwent dp - cect scanning using a 64-slice multidetector ct ( brilliance 64 ; philips , best , the netherlands ) with the following parameters : 360 ma ; 100 kvp ; rotation time 0.75 s ; detector collimation 64 mm  0.625 mm ; pitch 0.89:1 ; field - of - view 22 cm  22 cm ; and matrix 512  512 .
an iodinated nonionic contrast agent ( iopamidol [ 370 mg iodine / ml ] ; bracco , shanghai , china ) was administered intravenously at 5 ml / s using an electric power injector .
the contrast agent was dosed at 1.5 ml / kg according to the patient weight .
the arterial phase scan was trigged by the bolus - tracking program ( trigger bolus software ; philips , best , the netherlands ) after administering the contrast agent and performed in a cephalocaudal direction .
the ascending aorta served as the trigger point , and the trigger area was 200 mm .
the arterial phase scan time ranged 812 s. venous phase scanning was performed in the opposite direction after a fixed 8 s delay .
standard algorithms were used to reconstruct all arterial phase images , and standard and bone algorithms were used in all venous phase images .
multi - planar reconstruction images were generated on a workstation with a 1 mm slice thickness and no slice gap .
the axial images were reconstructed by setting the position baseline parallel to the bilateral lateral semicircular canals ; the coronal images were generated by setting the position baseline perpendicular to the bilateral lateral semicircular canals .
narrower settings ( width 700 hu ; level 200 hu ) were used to evaluate the arterial and venous systems , and bone window settings ( width 4000 hu ; level 700 hu ) were used to evaluate the sigmoid plates and temporal bones .
all ct images were individually evaluated by three radiologists with 5 , 6 , and 11 years of experience .
all findings were determined by consensus . the vascular anomalies and variants on symptomatic and asymptomatic sides were analyzed and evaluated retrospectively .
these evaluated vascular anomalies and variants were diagnosed on the following previously described criteria [ figure 1 ] : ( 1 ) high jugular bulb , the jugular bulb extended above the inferior border of the round window ; ( 2 ) dehiscent jugular bulb or dehiscent sigmoid plate , the incomplete thin bone around the jugular bulb or the sigmoid sinus ; ( 3 ) jugular bulb diverticulum , prominent protrusion or an irregular out - pouching of jugular bulb that was clearly distinguished from a smooth ellipsoidal form ; ( 4 ) sigmoid sinus diverticulum , a diverticulum entered into the mastoid bone ; ( 5 ) lateral sinus stenosis , the l / s ratio ( l = the largest area of the vein ; s = the smallest area of the vein ) was > 4.75 ; ( 6 ) large emissary vein , diameter of the emissary veins was > 3.5 mm ; ( 7 ) petrosquamosal sinus , embryologic emissary vein running along the petrosquamosal fissure ; and ( 8) sinus thrombosis , signs of thrombosis were noted , including the empty -sign or an irregular filling defect .
various vascular anomalies and variants of venous pulsatile tinnitus detected on venous phase computed tomography ( ct ) images in this study .
axial ct image ; ( a ) sigmoid sinus diverticulum ( arrow ) accompanying with a dehiscent sigmoid plate ( arrowhead ) .
axial ct image ; ( b ) a stenosis in right transverse sinus ( arrow ) .
axial ct image ; ( c ) a high jugular bulb ( arrow ) and axial ct image ; ( d ) a right jugular bulb dehiscence ( arrow ) .
sagittal ct image ; ( f ) a petrosquamosal sinus running into the temporal bone ( arrow ) .
axial ct image ; ( g ) a filling defect ( thrombosis ) in the superior curve of right sigmoid sinus ( arrow ) .
the venous sinus systems were classified into three types based on standards proposed by krishnan et al .
co - dominant venous systems were identified when the diameters of the bilateral mid - transverse sinus differed by  3 mm .
right or left dominant venous systems were identified according to the side with the largest diameter .
all statistical tests were performed using statistical software ( spss , version 17.0 ; spss , chicago , il , usa ) .
the vascular anomalies and variants on symptomatic sides and asymptomatic sides were counted and summed .
the incidences of the anomalies and variants were compared on each side using the chi - square test or the fisher exact test .
in addition , number of findings on the symptomatic side in each patient was calculated to analyze the anomaly and variant diversification of venous pt .
spearman rank correlation test was used to evaluate the correlation between the side of pt and the side of dominant venous system .
the number of lesions detected on the symptomatic side in each patient is summarized in table 1 . a total 228 ( 228/242 )
patients had at least one vascular anomaly or variant on the symptomatic side on ct .
of these 228 patients , 170 patients ( 170/242 ) had more than one anomaly or variant on the symptomatic side , and 58 patients ( 58/242 ) had only one anomaly or variant .
the summed number of vascular anomalies and variants on the symptomatic side in 242 venous pt patients * refer to the number of anomalies or variants detected on the symptomatic side of one pt patient .
there was statistically significant difference in the incidence of dehiscent sigmoid plate ( p = 0.000 ) , lateral sinus stenosis ( p = 0.014 ) , high jugular bulb ( p = 0.000 ) , sigmoid sinus diverticulum ( p = 0.000 ) , jugular bulb diverticulum ( p = 0.000 ) , dehiscent jugular bulb ( p = 0.000 ) , and large emissary vein ( p = 0.006 ) between the symptomatic and asymptomatic sides [ table 2 ] .
of these lesions , a dehiscent sigmoid plate , accounting for 86.4% of all venous pt patients , was the most frequent anomaly on the symptomatic side in this study .
no significant difference was found in the incidences of sinus thrombosis ( p = 0.249 ) and petrosquamosal sinus ( p = 1.000 ) between the symptomatic and asymptomatic sides .
the summarized vascular anomalies and variants detected on venous phase ct images of unilateral venous pt patients * fisher exact test .
pt : pulsatile tinnitus ; ct : computed tomography . of the 242 venous pt patients ,
right dominant venous systems were identified in 129 patients while 41 patients had left - sided systems .
there were 155 patients with pt on the dominant side of the venous systems and 15 patients with pt on the opposite side .
co - dominant systems were diagnosed in 72 patients ( 36 with left - sided pt ; 36 with right - sided pt ) .
the association between the side of pt and the dominant side of the venous system showed a moderate correlation according to the spearman rank correlation test (  = 103.78 , p = 0.000 , r = 0.55 ) .
we aimed to determine whether venous pt patients showed multiple vascular anomalies or variants on the pt side , which has rarely been assessed previously . to that end
, we detected with more than one vascular anomaly or variant on the symptomatic side in 170 patients ( 70.2% ) using ct , while only 58 patients ( 24.0% , 58/242 ) were diagnosed with a single lesion .
described a case of pt associated with both sigmoid sinus stenosis and ipsilateral jugular bulb diverticulum ; the tinnitus resolved after successful treatment of both conditions , which illustrates that the vascular pt lesion may not be singular .
similarly , our results suggested that the sound of venous pt may be triggered by multiple lesions within the veins .
this may explain why some venous pt patients experience no relief or report recurrence after a single surgery .
this is a novel finding for venous pt and implies that a single intervention of only one anomaly may not resolve pt completely .
therefore , it is crucial that radiologists identify every potential anomaly and variant on the symptomatic side on preoperative ct and sufficiently describe these lesions to clinicians .
in contrast to the anomalies described previously , such as a venous sinus stenosis and a high jugular bulb , a dehiscent sigmoid plate was the most frequent anomaly on the symptomatic side in the current study , diagnosed in 86.4% of all venous pt patients .
this discordance reflects certain anomalies and variants measured in this study that were not analyzed in previous studies .
furthermore , pt patients in previous studies were evaluated using different imaging methods , some of which are unable to detect a dehiscent sigmoid plate effectively , such as digital subtraction angiography , magnetic resonance imaging , and magnetic resonance angiography . in addition , the samples of venous pt patients in some studies were inadequate , which can compromise the validity of the results . in a study based on 15 pt patients with a dehiscent sigmoid plate ,
these studies confirm that a dehiscent sigmoid plate is a definite cause of venous pt , and reparative surgery could improve symptoms to some extent .
based on the results of the present study , the symptomatic side was significantly more likely to have a vascular anomaly or variant than the asymptomatic side .
recent studies reported that the venous hum of venous pt is caused by turbulent and nonlaminar blood flow , which is then transmitted to the cochlea .
the vascular anomalies and variants detected in this study are all factors potentially capable of changing normal perfusion ( such as a dehiscent sigmoid plate , lateral sinus stenosis , sigmoid sinus diverticulum or jugular bulb diverticulum , large emissary vein , petrosquamosal sinus , and sinus thrombosis ) or sound transmission ( such as a dehiscent sigmoid plate and dehiscent jugular bulb ) .
our results support the notion that venous pt is closely related to these vascular anomalies and variants . in the current study ,
the incidence of a high jugular bulb was significantly higher on the symptomatic side than on the asymptomatic side (  = 53.76 ; p = 0.000 ) .
however , there is an ongoing debate on the role played by the high jugular bulb in causing venous pt because this lesion is also common in asymptomatic patients .
however , pt also requires conditions that transmit the sound to the cochlea , like the dehiscent jugular bulb .
thus , a high jugular bulb should be considered a contributing factor to venous pt rather than a definitive cause . in other studies ,
similarly , in our study , venous pt was found more frequently in female subjects ( 215 , 88.8% ) .
this characteristic is likely associated with benign intracranial hypertension , which is common in women and can present with pt as the only symptom .
previous studies have reported a higher pt prevalence on the right - side , which could be associated with the right - sided dominance of the cerebral venous system .
our data were similar , and we diagnosed right - sided venous pt in 64.5% ( 156/242 ) of patients .
furthermore , the side of pt and the side of the dominant venous system showed moderate correlation ( p = 0.000 , r = 0.55 ) .
as friedmann et al . demonstrated in their study , cardiac venous pulsation from the dominant vein can strike the jugular sinus and cause expansion of the jugular bulb .
in addition , an increased diameter in the right - sided dominant vein increases the likelihood of turbulent flow than on the left - side .
dual - phase contrast - enhanced ct includes an arterial and venous phase , and can demonstrate the status of vessels and temporal bones simultaneously in a single study .
prospectively evaluated 16 pt patients and concluded that the dp - cect technique can effectively detect arterial , venous , and inner ear causes of pt . in our study ,
the dp - cect image demonstrated the details of each anatomic structure and ensured the accuracy of diagnosis .
this study had some limitations , including intrinsic bias secondary to a retrospective review and selection bias due to patients being recruited from a single tertiary care center .
a multi - center trial using a standardized imaging protocol would be ideal to evaluate venous pt patients .
second , in certain anomalies or variants , it was impossible to prove an association between venous pt and a therapeutic response in some cases .
however , all of these lesions have been reported or confirmed as contributing factors or causes of venous pt in previous studies .
additional study performing a comparison of venous variation incidence to normal control subjects in a large patient population is needed .
in addition , the weight of different vascular anomalies or variants in each patient was not analyzed in this study .
various vascular anomalies and variants can be detected more frequently on the pt side using dp - cect of venous pt patients .
in addition , preliminary findings suggest that venous pt patients may have multiple vascular lesions on the symptomatic side , which implies venous pt could be a consequence of multiple factors within the veins .
 background : a comprehensive assessment of various vascular anomalies and variants associated with venous pulsatile tinnitus ( pt ) by radiography is essential for therapeutic planning and improving the clinical outcome . 
 this study evaluated the incidence of various vascular anomalies and variants on the pt side and determined whether these lesions occurred as multiple or single entities.methods:the dual - phase contrast - enhanced computed tomography images of 242 patients with unilateral venous pt were retrospectively reviewed . 
 the vascular anomalies and variants on the symptomatic and asymptomatic sides were analyzed , and the incidences of anomalies or variants on each side were compared . 
 the number of anomalies and variants on the symptomatic side in each patient was calculated.results:(1 ) a total 170 patients ( 170/242 ) had more than one anomaly or variant on the symptomatic side , and 58 patients ( 58/242 ) had a single lesion on tomography . 
 ( 2 ) there was a statistically significant difference in the incidence of dehiscent sigmoid plate ( p = 0.000 ) , lateral sinus stenosis ( p = 0.014 ) , high jugular bulb ( p = 0.000 ) , sigmoid sinus diverticulum ( p = 0.000 ) , jugular bulb diverticulum ( p = 0.000 ) , dehiscent jugular bulb ( p = 0.000 ) , and a large emissary vein ( p = 0.006 ) between the symptomatic and asymptomatic sides . 
 ( 3 ) dehiscent sigmoid plate ( 86.4% ) was the most frequent lesion on the symptomatic side , followed by lateral sinus stenosis ( 55.8% ) , high jugular bulb ( 47.1% ) , sigmoid sinus diverticulum ( 34.3% ) , jugular bulb diverticulum ( 13.6% ) , dehiscent jugular bulb ( 13.6% ) , large emissary vein ( 4.1% ) , sinus thrombosis ( 1.2% ) , and petrosquamosal sinus ( 0.8%).conclusions : various vascular anomalies and variants occur more frequently on the venous pt side . 
 preliminary findings suggest that venous pt patients may have multiple vascular anomalies or variants on the symptomatic side . 
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