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The Study of Middle Cerebral Artery by Volume Computed Tomographic Digital Subtraction Angiography

Author: XieHui
Tutor: LvFaJin
School: Chongqing Medical University
Course: Medical Imaging and Nuclear Medicine
Keywords: Tomography X-ray computed Angiography threshold Volume rendering Models vessel opacity CT angiography models middle cerebral artery Volume computed tomography digital subtraction angiography anatomical Angiography Threshold values Vascular stenosis
CLC: R816.1
Type: Master's thesis
Year: 2011
Downloads: 30
Quote: 1
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Abstract

Objective: To investigate the influence of different medias on the CT measurement of calibre values of vessel models , volume rendering (VR) threshold and vessel caliber.Methods:Nine vessel models were filled with contrast material with nine different densities. The CT values of different vessel models were measured. the threshold was adjusted to measure vessel caliber,and recorded. The relationship of different media density, CT value of vessels, and standard threshold of CT and vessel model caliber were analyzed.Results: There was negative correlation between media density and CT value of vessel model(r=-1.000, P<0.01). Medium density for each increases 1HU, CT value and standard threshold of vascular model reduce 0.09 Hu respectively,also between media density and standard threshold (r=-1.000, P<0.01).Positive correlation was found between CT value of vessel model and standard threshold (r =1.000, P <0.01). There was a negative correlation between standard threshold and vessel model caliber (r=-0.78, P=0.01).Conclusion: vascular caliber measurements are affected by the media density, density of vessel model and VR reconstruction threshold.SECTION2: THRESHOLD MEASUREMENT AND AUTOMATED VESSEL ANALYSIS SOFTWARE IN CALIBER MEASUREMENT OF VESSEL MODELObjective:To evaluate the accuracy of calibre measurement of vessel model by 64-slice CT threshold measurement and manual method of measurement (AVA).Methods:Nine vessel models were filled with contrast material with nine different density.,then put models into nine media in different densities, the standard caliber of vessel model were measured by Vernier caliper. In the subsequent caliber were measured by automatic vessel analysis software (AVA) and threshold measurement on VR image. Vascular model calibers were measured by adjustment threshold in manual method. Accuracy of manual and automatic measurement of vessel model Caliber was compared.Results:The vessel model caliber was 10.71±0.08 mm in manual measurement group , there was no difference compared with the standard caliber of vessel model (P>0.05). The vessel model caliber was 12.15±0.41 mm in automatic measurement group, there was difference compared with the standard caliber (P<0.05). There were significant difference in caliber of vessel model by two methods (P<0.0001).Conclusion: For vessel model caliber measurement, threshold measurement was more accurately and better to reflect the true caliber of vessel model than automated measurement. Objective: To investigate the types of anatomical variations of M1 segment of middle cerebral artery and its branches on VCTDSA.Methods: Cerebral and cervical vessel VCTDSA scan of 120 normal adults (male 67, female 53) were performed and the images of middle cerebral arteries were reconstructed by volume reconstruction. The beginning of the middle cerebral artery diameter of MCA-M1 was measured with the computer tool. The courses and branch types of MCA-M1 were observed. The diameter differences between the left and the right and in gender were analyzed statistically.Results:The course of MCA-M1 was divided into brief level type 40.41%(97/240sides), the ramp-type 14.58% (35/240 sides), under the ramp-type 7.92%(19/240 sides), wave-type 37.08(89/240 sides), 7.91%(19/240 sides)of the middle cerebral arteries were the simple trunk type, 88.75%(213/240 sides)double trunk type and 3.33%(8/240 sides)tri-trunk. The measured values of MCA-M1 in VCTDSA:( 1.98±0.44 )mm on the left and (2.05±0.46 )mm on the right; (2.01±0.39 )mm in male , (2.03±0.41 )mm in female.The measured values of MCA-M1 in VCTDSA showed no differences between the left and the right ( P =0.062) and in gender(P=0.792). In addition to the branch types of MCA-M1 divided into eight types by Tanriover N, there is another three types: IIB subtype, IIC subtype and IVC subtype. This group of researchers found 2 cases of window-type variation of M1 segment, and 1 Accessory middle cerebral artery(Acc MCA), 5 cases of early bifurcation.Conclusion:VCTDSA can clearly demonstrate the course and variation of MCA-M1 segment, and its anatomic valuable reference for diagnosis of cerebral vascular diseases.SECTION2 COMPARISON ON VALUE OF THRESHOLD ADJUSTMENT AND CONVENTIONAL MEASUREMENT ON STENOSIS OF MIDDLE CEREBRAL ARTERYObjective:To evaluate the accuracy of middle cerebral artery stenosis with threshold adjustment and conventional measurement by volume CT digital subtraction angiography(VCTDSA).Methods:Eighty patients with middle cerebral artery stenosisn were analyzed with threshold adjustment and conventional measurement. And consistency through the intra-observer and inter-observer were assessed. Diameter of the stenosis and the normal vessel were measured, the rate and degree of stenosis were calculated.Results Intra-observer and inter-observer had a good consistency to determinate the narrow area (κ=0.99, 0.99 ) , threshold adjustment measurement and conventional measurement methods on the degree of stenosis was highly consistent by intra-observer (κ=0.92, 0.89) and inter-observer (κ=0.98,0.87). The detection of mild to moderate stenosis with threshold adjustment measurement were more than conventional measurement, including 2 mild and 1 moderate stenosis on M1 segment, 5 mild stenosis and 1 moderate stenosis on M2 segment. Threshold adjustment measurement was super to conventional measurement, there was significant difference in the measurement of stenosis vessel (P<0.01).Conclusion:The two measurements have a good consistency on the intra-observer and inter-observer. Threshold adjustment measurement can reduce the rate of missed diagnosis of mild to moderate stenosis artery, reflect the degree of stenosis more accurately, and provide a reliable basis for vascular stenosis images for clinical intervention.

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