64-Slice Spiral Computed Tomographic Angiography Of Cerebral Venous System And Clinical Application

PART 1 THE STUDY OF CEREBRAL VENOUS SYSTEM COMPUTED TOMOGRAPHIC ANGIOGRAPHYObjective: To discuss the display capabilities and advantages of subtraction technique of computed tomographic angiography (CTA) to the cerebral veins and venous sinuses.Methods: Dual-energy technology of synchronous scan with 64-slice CT was applied, which was at first plain scan and volume scan of arteriovenous CTA to show the integral cerebral vessels. According to the image data of head or head-and-neck CTA examination, 50 patients with normal vascular display were randomly selected. Retrospective analysis of convention and subtraction CTA was carried out on the display rate of cerebral veins, removal of cranium and basion, display of dural venous sinuses. The quality of VR and MIP images about cerebral veins were evaluated into four grades.Results: According to the images of subtraction CTA, the display rate of superior sagittal sinus, straight sinus, vein of Galen, septum pellucidum vein, internal cerebral vein, basal vein of Rosenthal, transverse sinus, sigmoid sinus, sphenoparietal sinus, inferior petrosal sinus, cerebral superficial vein, Labbe vein was all 100%, the rate of the inferior sagittal sinus was 99%, Trolard vein was 95%, the superior petrosal sinus 90% and the cavernous sinus 60%. There was no significant difference in the display rate of the above veins between conventional and subtraction CTA except the inferior, superior petrosal sinus and the cavernous sinus. However, the display extent varied, the images of subtraction CTA were direct with clear anatomical details and integral vessels, which was superior to convention CTA. Convention CTA could display the relationship between cerebral vessels and the corresponding clearly with the feature of skull localization. Due to removal of skull, subtraction CTA could display the whole of cerebral venous system anatomic structure clearly, integrate the advantages of a variety of post-processing techniques and avoid the influence of setting the threshold value on images. The MIP images of subtraction CTA displayed vascular background more clearly than the VR images, and the VR images displayed vascular details more clearly than the MIP images.Conclusion: The subtraction technique could display not only larger intracranial veins and venous sinuses clearly with the rate of 100%, but also the smaller sinuses, such as the superior petrosal sinus and sphenoparietal sinus with a higher rate. Subtraction CTA is a feasible and effective method for cerebral venous imaging. Subtraction CTA and convention CTA can be complementary with valuable clinical application.PART 2 IMAGING ANATOMICAL STUDY OF THE STRAIGHT SINUS AND RELATED STRUCTURESObjective: To discuss the CTA performance of the straight sinus and related anatomical structure.Methods: Retrospective three-dimensional reconstruction of the straight sinus and related vascular structures was carried on 100 cases of head or head-and-neck CTA with 64-slice CT. The anatomy of the straight sinus, confluens sinus, inferior sagittal sinus and persistent falcial sinus was observed on the views of volume rendering(VR), maximum intensity projection (MIP), multiplanar reconstruction(MPR) by convention and subtraction CTA. For the straight sinus, the morphology of the galea vein into straight sinus and the top of the straight sinus, the lumen, partitioning type and arachnoid granulations of the straight sinus, and vessels into the straight sinus was observed, and the length of the straight sinus, width of the bilateral and proximal walls, and the cross section area of the anterior, middle and posterior regions were measured. For the confluens sinus, the anatomical type, inosculating relationship between the bilateral transverse sinus, display of the occipital sinus and drainage superiority of the transverse sinus were observed. For the inferior sagittal sinus, the morphology was observed, the length and the cross section area of the middle region were measured. For persistent falcial sinus, the display rate, morphology and any other sinus variation were observed, the length of the sinus and width of the midpoint were measured.Results:①According to the morphology and lumen of the end of the galea vein, the morphology of the galea vein into straight sinus was divided into three types: typeⅠ- the lumen became thin, which was divided into three subtypes ofⅠa,Ⅰb,Ⅰc, on the basis of different ways in which the transverse and longitudinal diameter of the lumen become thin; typeⅡ- the lumen didn't become thin with gap; typeⅢ- the proximal wall of the galea vein flowed into straight sinus with filling defect. The length of the straight sinus was 70 mm longest, 34.5 mm shortest, with the mean of 47.72±6.29mm; the left and right walls of straight sinus were of similar width, with wider anterior and posterior region and smaller middle region; the proximal wall was gradually becoming wider from the anterior to posterior, the cross section of which was a triangle with unequal edges. Straight sinus top can be summed up into seven types as follows: 35 cases of Arc shape, 28 cases of "-" shape, 24 cases of inverted "V" shape, 8 cases of irregular shape, 3 cases of column, one case of T shape, one case of double-peak. The straight sinus with septa inside was 58 per cent, without septa was 42 per cent; fiber septa can be distributed in all regions of the sinus with the performance of line, mesh, irregular negative shadow varying in length on the view of MIP, the length of which 40.4 mm longest, 2 mm shortest, with the mean of 9.96±6.95mm. The type of straight sinus are high to low from the anterior to posterior, which can be divided into straight and curved type by whether bending or not, with 61% of linear type, 39% curved type; according to relationship between the straight sinus pressure and corpus callosum, the straight sinus was divided into tangent, superior and inferior types. 16 arachnoid granulations were found, with the smallest diameter of 1.2 mm, maximum diameter of 6.2 mm. The straight sinus received the blood of not only the galea vein and superior sagittal sinus, but also of veins or sinuses of tentorium of cerebellum and cerebellar veins, variation of the basal vein. There were 14 cases without any vein above into the straight sinus, 86 cases with the veins into the straight sinus through all the walls especially the junction of the proximal and lateral walls.②The anatomical structure of torcular herophili was classified into simple confluence (20%), double bifurcation (37%), and dural venous sinuses deviation (43%).Dural venous sinuses deviation was subdivided into 3 subtypes according to the different deviation of the superior sagittal sinus and the straight. The display rate of occipital sinus is 2%, most are absence. Overall, the venous drainage dominance showed mainly to the right side. Indirect communications between transverse sinuses were common.③The inferior sagittal sinus,65% of display,35% of the absence;with the morphology of campylodromous, the lumen could be of different size with intermittent performance for the filling of contrast agent. The length of inferior sagittal sinus was 99.9 mm longest, 41.2 mm shortest with the mean of 74.64±13.43mm, the cross section area of the middle region was 1.82±1.90mm2 at average.④The display rate of the persistent falcial sinus was 9%, with 4 cases of any other developmental variations; The length was 40.95±12.11mm at average, the width of the midpoint was 4.09±2.04mm at average; The anterior border to top of the straight sinus was of acute angle, right angle and obtuse angle, especially acute angle; The end connected with not only the superior sagittal sinus, but also the superficial cerebral veins at left and right top; The direction could be curvedly or obliquely upward, or horizontal; the lumen was not displayed in a whole range but cut off.Conclusion:The straight sinus and related anatomical structures are complicated features, and MSCTA can be used to display individually, sufficiently, completely and effectively, which can help to diagnose and treat the corresponding diseases for clinic. PART 3 DIAGNOSTIC VALUE OF SUBTRACTION COMPUTED TOMOGRAPHIC ANGIOGRAPHY IN CEREBRAL VENOUS SINUSES DISEASESObjective:To evaluate the diagnostic value of subtraction computed tomographic angiography in cerebral venous sinuses diseases. Methods: Retrospective research was carried out on the image data of 51 cases with cerebral venous sinuses diseases and other diseases involving cerebral venous sinuses(part confirmed by DSA and/or surgery), by head or head-and-neck scanning with 64-slice CT. The performance of CT and CTA about above diseases, the image quality of subtraction were analyzed. Results: There were 5 cases of cerebral venous sinus thrombosis, 21 cases of arteriovenous malformation, 8 cases of venous malformation, 7 cases of tumor-involved sinus, 7 case of carotid-cavernous fistula , 2 cases of trauma-involved sinus and one case of trauma-involved bridging vein diagnosed by CTA with focus displaying rate of 95%, Image quality of subtraction was good and vessels were displayed clearly, which was in overwhelming majority of 90%. But only in few cases, the cranium and skull base could not be completely removed due to slightly motion of head, which did not influence diagnosis by combining with other postprocessing techniques, such as VR, MIP and MPR.Conclusion: Subtraction technique of computed tomographic angiography is a reliable, effective and worthy of wide clinical application.