| PART ONE ANALYSIS OF IMAGING SIGNS AND DIAGNOSTIC VALUE OF MSCT IN ACUTE APPENDICITISObjective: The aim of this study is to analyze the imaging signs of MSCT plain scanning of acute appendicitis,to evaluate the value of various imaging signs in the diagnosis of acute appendicitis,and to compare the diagnostic efficacy of various imaging signs in distinguishing acute appendicitis of different pathological types.Materials and Methods: A retrospective analysis of 71 cases with acute appendicitis confirmed by surgery and pathology from November 2016 to March 2019,and by clinical follow-up confirmed 43 cases without acute appendicitis as a control group.All patients had no preparation for the gastrointestinal tract before examination,using a 16/64-MSCT to plain scan(Neusoft Neuviz 16,Siemens Somatom Definition Edge 64).The range from the xiphoid to the symphysis pubis or from the upper edge of the third Lumbar vertebra to the symphysis pubis.To evaluate the sensitivity,specificity and accuracy of each imaging sign of MSCT plain scanning in the diagnosis of acute appendicitis,which including some changes of appendix(appendiceal diameter,wall thickening,intraluminal fluid,tension bloating,appendicolith,appendicolith incarcerating,fat stranding or turbiding,adjancent bowel wall thickening,intraluminal air,small bubble sign,extraluminal air,extraluminal fluid,enlarged mesenteric lymph nodes and small intestinal obstruction).To compare the incidence of various MSCT imaging signs between acute appendicitis group and control group and to compare this among various pathological types of acute appendicitis,to analyze appendiceal diameter,wall thickening and intraluminal fluid among three different pathological types of acute appendicitis using one-way analysis of variance(ANOVA).Results: The value of single MSCT imaging sign in the diagnosis of acute appendicitis was limited,and its sensitivity,specificity and accuracy varied greatly,ranging from 1.4% to 98.6%,24.4% to 100%,20.7% to 91.9% respectively.Among them,there were significant differences in the probability of acute appendicitis and non-acute appendicitis(P<0.01)in diameter swelling,wall thickening,intraluminal fluid,tension bloating,appendicolith incarcerating and fat stranding.And these imaging signs including appendiceal wall thickening,extraluminal fluid,tension bloating,fat stranding or turbiding and adjancent bowel wall thickening were valued to judge different types of acute appendicitis(P< 0.01).Conclusion: MSCT plain scanning is quick and convenient,which has high value in diagnosis and differential diagnosis of acute appendicitis,and also has certain reference value in distinguishing acute appendicitis of different pathological types.PART TWO THE VALUE OF MSCT WITH LOW-DOSE SCAN BASED ON ABDOMINAL TRANSVERSE DIAMETER IN THE DIAGNOSIS OF ACUTE APPENDICITISObjective: To investigate the value of low-tube current CT scan based on the transverse diameter of abdominal topogram in the diagnosis of acute appendicitis.Materials and Methods: Abdominal CT examination was performed on patients with clinical appendicitis.According to the transverse diameter(D)measured by scanning topogram,which were divided into three groups: large,medium and small: large transverse diameter group(D large),D large> 34 cm,medium diameter group(Dmedium),28cm?Dmedium ?34cm,small transverse diameter(D small),D small <28cm.The default tube current were(Sm As,220 m As),0.7Sm As 0.3Sm As,and the tube current mode was selected as automatic tube current(ACS)+ dose modulation(DOM).Image quality evaluation and diagnosis were performed on the inspection images of three groups of different radiation doses.The CT volumetric dose index(CTDIvol)and the dose length product(DLP)were compared to pathology results and compared the efficacy of the three groups in the diagnosis of acute appendicitis.Results: The DM values of the abdominal topograms in the D large,Dmedium,and D small groups were(36.67±3.31)cm,(30.66±1.76)cm,(26.41±1.42)cm,and the difference was statistically significant(F=223.60),P < 0.001);CTDIvol values were(10.28 ± 1.57)m Gy,(6.59 ± 0.91)m Gy,(3.63 ± 0.13)m Gy,the difference was statistically significant(F = 413.53,P < 0.001);DLP values were(419.80±40.39)m Gy·cm,(235.83±11.03)m Gy·cm,(138.61±6.24)m Gy·cm,the difference was statistically significant(F=1644.60,P<0.001);CTDIvol comparison between the three groups,there was significant difference in DLP values between the two groups(all P<0.01).There was no significant difference between the three groups in the diagnosis of acute appendicitis and CT(all P>0.05).The sensitivity,specificity,positive predictive value,negative predictive value and accuracy were 100%(27/27),50%(1/2),96.43%(27/28),100%(1/1),96.55%(28/29)and 94.29%(33/35),100%(2/2),100(35/35),50%(2/4),94.59%(35/37)and 87.5%(14/16),100%(4/4),100%(14/14),66.67%(4/6),90%(18/20)respectively.Conclusion: The CT scanning protocol of low-dose with different tube current based on the transverse diameter of abdominal topogram can reduce the radiation dose of the patient,and it is easy to operate and can be used for the diagnosis of acute appendicitis. |
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