| Objective:To investigate the normal imaging anatomy structure and viration of superior mesenteric arteries (SMA) by 64 spiral CT angiography(64-SCTA); and to evaluate the demonstrating ability in superior mesenteric arteries and to discuss the characteristics of image and clinical value of common diseases of SMA. Materials and Methods:164 patients with no associated disease involved SMA and its distributing region and 48 patients with associat-ed disease involved SMA and its distributing region underwent 64-SCTA scan, then the acquired original datas after being reconstructed by 0.625 slice thick were passed to ADW4.3 station to be postprocessed, adopting different methods including multiplanar reconstruction (MPR), volume rendering (VR), maximum intensity projection (MIP), sliding thin slab maximum vs minimum projection (STS-MIP), and vessel analaysis (VA). Normal set:To observe and analyze the three dimensional anatomy structure of SMA, including the origin segment path, total length, branch arteries and the diameter of SMA; To measure the angle between SMA and aorta (AA), the distance between SMA and AA in the plane of left renal vein (LRV) and duodenum horizontal part (DHP), the diameter of LRV going across SMA and AA,and the maximum diameter of LRV in the left kidney portal. To compare the demonstrating ability of SMA and its communi-cating arteries and observe the quality of image by various reconstructtion methods. All datas were analyzed by the SPSS13.0 software progress.In abnormal set:By various reconstruction techniques to demonstrate the SMA, and to analyze the characteristics of pathological and associated pathological in SMA. Results:Among 164 cases with no associated disease in SMA or its distribution region,140 cases is normal in the pathway and distribution region of SMA. Among the above 140 cases,74 cases is male,66 cases is female, and the average is 52 years old; The remained 24 cases exist anatomy variation. In normal set, the whole anatomy structure of SMA can be clearly demonstrated by MPR, VR, MIP and STS-MIP. MPR sagittal bits can directly display the anatomic relationship of original segment of SMA and the closed blood vessel, such as AA,LRV and so on. The pathway of origin segment of SMA presenting turn (A type) was 80 cases, and presenting striate (B type) was 60 cases; The angle between SMA and AA was 56.6°±24.1°,95% Confidence interval was (52.6°～60.6°). The distances between SMA and AA in plane of LRV were 13.51 mm±6.48 mm,95% Confidence interval was (12.42～14.59) mm; The diameters of LRV going across SMA and AA were 5.60mm±1.91mm,95% Confidence interval was (5.28～5.92)mm; The maximum diameters of LRV in the left kidney portal were 9.97 mm±1.47mm,95% Confidence interval was (9.73～10.22)mm; The average distances between SMA and AA in plane of DHP were 13.09mm±6.17mm,95% Confidence interval was (12.06～14.12) mm. In normal set, the angle between SMA and AA in type A was 72.9°±17.2°, 95% Confidence interval was (69.1°～76.7°). The distances between SMA and AA in plane of LRV were 17.39mm±5.99mm,95% Confidence interval was (16.1～18.7)mm. The diameters of LRV going across SMA and AA were 6.22 mm±1.90mm,95% Confidence interval was (5.80～6.64)mm.The maximum diameters of LRV in the left kidney portal were 9.99mm±1.54mm,95% Confi-dence interval was (9.65～10.31)mm.The distances between SMA and AA in plane of DHP were 15.57mm±6.24mm,95% Confidence interval was (14.18～16.96)mm. The angle between SMA and AA in type B was 34.3°±9.9°,95% Confidence interval was (31.8°～36.9°). The distances between SMA and AA in plane of LRV were 8.43mm±2.57mm,95% Confidence interval was (7.77～9.10)mm. The diameters of LRV going across SMA and AA were 4.74mm±1.55 mm,95% Confidence interval was (4.34～5.14)mm. The maximum diameters of LRV in the left kidney portal were 9.95mm±1.38mm,95% Confidence interval was (9.60～10.31)mm. The distances between SMA and AA in plane of DHP were 10.19mm±5.10mm,95% Confidence interval was (8.87～11.51)mm. The angel and distance between SMA and AA was related to the pathway of SMA(P<0.05),but not related to sex or age (p>0.05). The diameter of LRV going across SMA and AA was related to the angle between them, but the maxium diameters of LRV in the left kidney portal is not related to the pathway of SMA (p>0.05). SMA has many branches,the number of which varies from 11 to 15, and the average is 12. Comparing the ability of demonstrating SMA and its branch arteries, there was no statistical meaning (p> 0.05) in demonstrateing the major branch andⅡ～Ⅲlevel branch arteries of SMA by MPR, VR, MIP and STS-MIP, and there was statistical meaning (p<0.05) in demonstratingⅣ～Ⅴlevel branch arteries comparing MPR and STS-MIP to VR and MIP, meaning MPR and STS-MIP have advantage over VR, MIP in demonstrating tiny vessel. STS-MIP also has special advantage in displaying the net of vessel in SMA or around it. Amonge the different reconstruction, the image of Stand,Soft and Detail is better, but the image of Bone is unwell and can't to make analysis in vessel of abdomen. The length of SMA was 19.8cm±2.2cm, the diameter was 6.8mm±1.1mm in plane of LRV, and the minimum diameter of SMA can reach to 1mm～2mm with VA technology. Among 24 cases which exists anatomy varition, SMA and celiac trunk derive from the same vessel (n=8); Common hepatic artery, Right hepatic artery, Left hepatic artery and Splenic artery derive from SMA (n=16). Among the abnormal cases of 48, SMA ischemic changes (n=12), MPR display the soft patch in the lumen and narrow of SMA, MIP display sclerosis plaque in the vessel wall,VR display the narrow or discontinue of SMA;The dissection of SMA (n=6), MPR and VR can display the inner membrane and double cavity image; The intestine volvulus and Intestinal intussusception (n=12), On axial images of the intestine volvulus, the "whirlpool" sign of mesentery vessels were showed, The VR display "whirlpool" of SMA But intussusception showed target sign or cocentric circle sign and blood vessels curling sign. NCS and SMACS (n=7), Among them,4 cases of NCS the average angel between SMA and AA was 17.3°, the distance between SMA and AA in the plane of LRV was 3.8mm.3 cases of SMACS, the average angel between SMA and AA was 14.4°, the distance between SMA and AA in the plane of DHP was 5.8mm. The gastronintestinal tumor (n=11), VR and STS-MIP all displayed the blood supplying relationship between SMA and its branch arteries in tumor. Conclusion:64-SCTA is a high resolution, accurate, fastspeed and noninassive angiograpy method, and its various postprocessing methods can clearly demonstrate the normal three dimensional anatomy structure and variation of SMA, It can accurately measure the angle and distance between SMA and AA; The spacial anatomy in organism exists obvious variation, especially when SMA goes striate, the angle between SMA and AA becomes smaller, which is a potential agent in causing SMA compressing diseases. Furthermore,64-SCTA has a better demonstrating ability for SMA and its branch arteries, making it suitable to observe the relation between the tiny branches of vessel and surrounding tissue. Especially it has obvious advantage when display SMA, CA, IMA and the communicating branches vessel among themselves,which matters much to assese the esistence of collateral circulation. At the same time,64-SCTA can characteristically display various diseases of SMA, and making it suitable to guide and help clinical docters to improve the diagnosis and knowledge, which it has important value to assess the dangeriousity of patients condition and to choose clinical scheme.
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