The Diagnostic Value Of Multi Slice Spiral CTA In SAH

Computed tomographic angiography (CTA)is annon-invasive diagnostic imaging method for intracranialcerebrovascular diseases. This technology, which firstappeared in 1989, can reconstruct vessels inthree-dimensional way based on modern computertechnology .The basic principle of CTA is collectingprimary data of target vessels when contrast medium, whichis intravenously administrated through the cubital veinconcentrates, then utilizing the post-processingfunction of computer, and finally reconstruct thedimensional image of target vessels. Previous studiesabout CTA suggest that CTA has advantages in diagnosis,showing three-dimensional picture of locus and it can beobserved from any angle. It can observe the internalstructure of the loci, vascular walls, the relationshipof locus to adjacent structures as well as aneurysmcarrying artery. The sensitivity and specificity of CTAare close to those of DSA .Therefore many studies havesuggested CTA can be first-choice modality. With the rapiddevelopment of CT technology, which advanced from 1 slice,to 4 slices, 8 slices even to 64 slices, allowing CT toscan faster, to scan thinner slice, and to be moreinformational, and more powerful in post-processingsoftware, the prospect of CTA is much brighter. And thereis an increasing trend that CTA takes the place of DSA.16 slice spiral CT , representing the new generation ofCT ,can scan faster, with thinner slice(0.625 mmminimum),and contain more information ,withpost-processing image is more accurate and clear. Allthese characters lend an edge in CTA diagnosis. The aimof this study is to identify the advantages of CTAperformed by multi-slice spiral CT, whether CTA canreplace DSA in the diagnosis of cerebral aneurysm ,andprovide evidence for reasonable choice of diagnosticmodality in clinical practice.Digital Subtraction Angiography (DSA), subtract theimage of the locus before injected contrast mediumintravenously from the image of the same locus aftercontrast medium administration ,leaving only the image ofblood vessels containing contrast medium whileeliminating the background information such as skeletonand soft tissues.Subarachnoid Hemorrhage (SAH) is the general situationin which cerebral vessel abrupt caused by various reasonsand blood rushes to the subarachnoid sinus. SAH can bedivided into spontaneous and traumatic types.Intracranial aneurysm (AN), namely cystic bulge ofintracranial artery, is primary cause of spontaneous SAH,accounting for 70~85%. The mortality and mutilation rateare both very high. Early accurate diagnosis and timelytreatment is clinically significant for the prognosis .Atpresent the common diagnosis modality is MagneticResonance Angiography (MRA), Digital SubtractionAngiography (DSA), Computed Tomography Angiography (CTA).Although it is a noninvasive diagnostic modality, MRA isnot widely used because its result is affected by bloodflow rate and performing time is rather long. DSA isconsidered the golden standard for diagnosingintracranial aneurysm. However ,DSA isinvasive ,traumatic , and radiative, with longerperforming time ,more complications and higher cost Thesedisadvantages is unfit for aneurysm screening .Since DSAexam requires a time lag of more than 5 hours from onsetof disease to be performed, it is quite likely thatperforming DSA can delay the diagnosis and treatment ofdisease .On the contrary , CTA possesses the property ofmini-invasive ,rapid procedure ,low cost ,lesscomplications and contraindications, high sensitivityand three-dimensional images, thus recently it is widelyused in clinical practice. With the development ofmulti-slice spiral CT, more information is provided toincrease the accuracy of CTA.To investigate the advantages of multi-slice spiralCTA in diagnosing the intracranial aneurysm, we design ourstudy as follows: we include spontaneous SAH patients whois suspected of aneurysm, then evaluate the CTA resultson the basis of surgical findings, and finally explore theadvantages and disadvantages of CTA diagnosis. Our studyhelps us understand the value of multi-slice spiral CT inthe application of CTA, and provide evidence fordiagnostic and treatment modality of aneurysm.