| Part ? Correlation between body fat parameters and the severity of acute pancreatitis:A quantitative CT studyObjective At present,the studies on body fat parameters in acute pancreatitis(AP)are mainly presented as abdominal circumference,subcutaneous fat volume and visceral fat volume.However,little is known about refined anatomical fat volume in AP patients.In this study,we used CT quantitative method to investigate the relationship between body fat parameters of abdominal anatomical spaces and the severity of AP.Methods According to inclusion criteria and exclusion criteria,211 patients with AP admitted to our hospital between September 20,2017 and June 30,2019 participated in this study.CT scans were performed on Somatom Sensation 16,Siemens Medical Solutions,Erlangen,Germany CT scanner or GE Healthcare,Milwaukee,WI,USA CT scanner.The images were transferred to the post-processing workstation for reviewing.On the initial CT images,abdominal fat distribution was assessed based on anatomical regions,including abdominal circumference,subcutaneous fat area,peritoneal cavity fat area,bilateral posterior pararenal space fat areas,and bilateral perirenal fat areas.Student's t test or Mann-Whitney U test was used for comparison between quantitative data sets.Quantitative data of the three groups were compared using one-way analysis of variance(ANOVA).The Pearson x2 test or Fisher's exact method was used to compare qualitative data groups.The correlations between body fat parameters and the severity of AP were analyzed by Spearman rank correlation.The receiver operating characteristic(ROC)curve analysis was used to quantitatively predict the diagnostic capability of severe acute pancreatitis according to the 2012 Revised Atlanta Classification(RAC).Results The demographic characteristics of a total of 211 hospitalized patients with AP were as follows:119(56.4%)males and 92(43.6%)females,aged 52.9±16.5 years(20-94 years).According to the RAC 2012,there were 72 cases of mild acute pancreatitis(MAP)(34.1%),99 cases of moderately severe acute pancreatitis(MSAP)(46.9%),and 40 cases of severe acute pancreatitis(SAP)(19%).According to the CTSI/MRSI system,the CTSI/MRSI score of 211 cases was 5.4±2.5 points(1-10 points).The CTSI/MRSI was 2.6±0.6 points(1-3 points)in the 72 patients with MAP,6.2±1.7 points(4-10 points)in the 99 patients with MSAP,and 8.5±1.1 points(6-10 points)in the 40 patients with SAP.The CTSI/MRSI scores of mild,moderate and severe groups were statistically different(F=277,P<0.001).CT quantification fat parameters of the 211 patients with AP were given as follows:abdominal circumference of 91.3±8.8 cm(62cm-118cm),subcutaneous fat area of 199.8±68.1cm2(31cm2-384cm2),intraperitoneal fat area of 105.7±37.9cm2(22cm2-275cm2),bilateral posterior pararenal space fat areas of 30.4±10.5cm2(6cm2-66.8cm2),and bilateral perirenal fat areas 82.8±23.2cm2(11cm2-148cm2).Abdominal circumference was mildly correlated with the severity of AP(rs=0.238,P<0.001).Compared with CTSI/MRSI score(when CTSI/MRSI?7 points,the predicted sensitivity and specificity of SAP were 97.5%and 83.6%,P<0.001),the sensitivity and specificity of SAP were predicted to be 60%and 68.4%,with AUC=0.611[95%CI:0.496-0.727,P=0.028],when abdominal circumference was?93.3cm.Subcutaneous fat area was mildly correlated with the severity of AP(rs=0.178,P=0.009).When subcutaneous fat area was?208.5cm2,the sensitivity and specificity of SAP were predicted to be 62.5%and 60.2%,with AUC=0.612[95%CI:0.513-0.711],P=0.028.The mean value of fat area in peritoneal cavity increased as the severity of AP increasing,but there were no statistical differences between the three groups(F=1.785,P=0.17).In addition,bilateral posterior pararenal space fat areas were positively correlated with the severity of AP(rs=0.423,P<0.001).The sensitivity and specificity of SAP were 70%and 55.6%,with AUC=0.673(95%CI:0.577-0.768),when fat areas of bilateral posterior pararenal space were?29.2cm2.There was an increasing trend in the mean value of bilateral perirenal fat areas in the mild group,the moderately severe group and the severe group,but there were no statistical differences between the three groups(F=2.284,P=0.104).Conclusions Using CT quantification,abdominal circumference,subcutaneous fat area,peritoneal cavity fat area,bilateral posterior pararenal space fat areas,bilateral perirenal fat areas in patients with AP showed an increasing trend in mean values of mild group,moderately severe group and severe group.Abdominal circumference,subcutaneous fat area and bilateral posterior pararenal space fat areas were mildly correlated with the severity of AP.Compared with the CTSI/MRSI,none of the abdominal fat parameters on quantitative CT had sufficient diagnostic capacities to predict SAP based upon the 2012 Revised Atlanta Classification.Part ? Correlation between the volume of effusions and the severity of acute pancreatitis:A quantitative CT study and anatomical basisObjective The existing imaging studies have focused mainly on adults showing the qualitative results of different anatomical sites in acute pancreatitis(AP).However,there are few quantitative studies on the relationship between different anatomical site effusions and the severity of AP.In this study,we used CT quantitative method to investigate the correlations between CT quantification of effusions in bilateral pararenal anterior spaces,left subphrenic and extraperitoneal space,and bilateral posterior pararenal spaces and the different severity of AP based on the Revised Atlanta Classification(RAC)2012.Methods According to inclusion criteria and exclusion criteria,211 patients with AP admitted to our hospital between September 20,2017 and June 30,2019 participated in this study.CT scans were performed on Somatom Sensation 16,Siemens Medical Solutions,Erlangen,Germany CT scanner or GE Healthcare,Milwaukee,WI,USA CT scanner.The images were transferred to the post-processing workstation for reviewing.On the initial CT images,region areas of interest(ROIs)were delineated to measure the amount of effusions in bilateral pararenal anterior spaces,left subphrenic and extraperitoneal space,and bilateral posterior pararenal spaces.In addition,13 cadavers(all male)were embalmed for one year in the anatomy department of Wuhan university,and three of them underwent sectional anatomy study.Areas of interest were observed and the photos were saved on our PC.Student's t test or Mann-Whitney U test was used for comparison between quantitative data sets.Quantitative data of the three groups were compared using one-way analysis of variance(ANOVA).The Pearson x 2 test or Fisher's exact method was used to compare qualitative data groups.The correlations between the amount of effusions in different anatomical sites and the severity of AP were analyzed by Spearman rank correlation.The receiver operating characteristic(ROC)curve analysis of them was used to quantitatively predict the diagnostic capability for severe acute pancreatitis according to the 2012 RAC.Results(1)The demographic characteristics of a total of 211 hospitalized patients with AP were given as follows:119(56.4%)males and 92(43.6%)females,aged 52.9±16.5 years(20-94 years).According to the RAC 2012,there were 72 cases of mild acute pancreatitis(MAP)(34.1%),99 cases of moderately severe acute pancreatitis(MSAP)(46.9%),and 40 cases of severe acute pancreatitis(SAP)(19%).(2)According to 139 patients with MSAP and SAP classified as RAC 2012,100%(139/139)showed effusions in the left pararenal anterior space on the initial CT images,and the mean effusion volume was 14.7±12.6cm2(1cm2-85cm2).96.4%(134/139)showed effusions in the right pararenal anterior space,and the mean amount of effusion was 11.5± 12.2cm2(1.2cm2-80cm2).The volumes of effusions of SAP in the left pararenal anterior space and right pararenal anterior space were both greater than those of patients with MSAP(t=8.602,P<0.001;t=7.064,P<0.001).The volumes of effusions in the left pararenal anterior space and right pararenal anterior space were positively correlated with the severity of AP(R2=0.351,P<0.001;R2=0.267,P<0.001).When the effusion volume in the left pararenal anterior space was?14.8cm2,the sensitivity and specificity for SAP were predicted to be 85%,69.7%,with AUC=0.864(P<0.001)depending on RAC.When the effusion volume in the right pararenal anterior space was? 11.4cm2,the sensitivity and specificity for SAP were predicted to be 72.5%,75%,with AUC=0.849(P<0.001).(3)91.4%(127/139)showed effusions in left subphrenic and extraperitoneal space on the initial CT images,and the mean effusion volume was 5.8±4.2cm2(1cm2-22.2cm2).The mean volume of effusion of SAP in left subphrenic and extraperitoneal space was greater than that of patients with MSAP(t=12.21,P<0.001).The effusion volume in left subphrenic and extraperitoneal space was positively correlated with the severity of AP(R2=0.52,P<0.001).When the effusion volume in the left subphrenic and extraperitoneal space was? 8.1cm2,the sensitivity and specificity for SAP were predicted to be 87.5%,and 91.9%,with AUC=0.948(P<0.001).(4)71.2%(99/139)and 67.6%(94/139)showed effusions in left posterior pararenal space and right posterior pararenal space on the initial CT images,respectively.The involvement rates of SAP in the left posterior pararenal space(53.5%±18.3%)and right posterior pararenal space(32.3%±20.2%)were greater than those of patients with MSAP(13.4%±14.6%;t=13.61,P<0.001);(12.8%±14.1%;t=6.454,P<0.001).When the involvement rate in the left posterior pararenal space was?36%,the sensitivity and specificity for SAP were predicted to be 85%,and 90.9%,with AUC=0.957(P<0.001).In addition,when the involvement rate in the right posterior pararenal space was?20.5%,the sensitivity and specificity for SAP were predicted to be 72.5%,and 66.7%,with AUC=0.783(P<0.001).(5)Cadaver specimens and cross-sectional specimens showed that bilateral anterior renal fascia structures were composed of two or three membranous leaves(anterior and posterior layers).The anterior layer of the left anterior renal fascia passes to the right at the posterior border of the horizontal segment of the duodenum,and the posterior layer of the left anterior renal fascia passes over the anterior border of the abdominal aorta and communicates with the connective tissue membranes surrounding the inferior vena cava.The anterior layer of the right anterior renal fascia runs to the left at the anterior edge of the descending segment of the duodenum,and the posterior layer runs to posterior edge of the descending segment of the duodenum,and it converges into the connective tissue membrane surrounding inferior vena cava.The left subphrenic extraperitoneal space has the largest range at the sagittal part of the left branch of hepatic portal vein,and it descends adjacent to the upper portion of the left perirenal fat sac/perirenal space.Moreover,there are three anatomical pathways of effusions involving posterior pararenal spaces.Conclusions Quantification of effusions in different anatomical spaces associated with AP can be used in the differential diagnosis of MSAP and SAP.Compared with the diagnostic performance of the CTSI/MRSI,the involvement rate of left posterior pararenal space,the amount of effusion in left subphrenic and extraperitoneal space,the amount of effusion in left pararenal anterior space,and the amount of effusion in right pararenal anterior space are of more clinical value for the diagnosis of SAP according to the RAC 2012.There are corresponding anatomical spread pathways in bilateral pararenal anterior spaces,left subphrenic extraperitoneal space and posterior pararenal spaces.Part ? CT/MR imaging and anatomical study of abdominal wall edema in acute pancreatitisObjective To date,it is not clear whether the imaging changes in abdominal walls associated with acute pancreatitis(AP)could predict severe acute pancreatitis based upon Revised Atlanta Classification(RAC)2012.The anatomical mechanisms by which AP leads to signs of abdominal wall edema in different sites are not clear.(1)Use magnetic resonance imaging(MRI)to analysis the abdominal wall characteristics of patients with AP,and to investigate the clinical value of abdominal wall edema scoring system in predicting severe acute pancreatitis based upon the RAC 2012.(2)To seek spread pathways of AP-related abdominal wall edema on MRI,and to further explore the pathogenesis in different anatomical parts by analyzing gross specimens and local sections of cadavers.Methods According to inclusion criteria and exclusion criteria,211 patients with AP admitted to our hospital between September 20,2017 and June 30,2019 participated in this study.CT scans were performed on Somatom Sensation 16,Siemens Medical Solutions,Erlangen,Germany CT scanner or GE Healthcare,Milwaukee,WI,USA CT scanner.Siemens Magnetom Trio 1.5T and 3.0T superconducting scanners(Magnetom Prisma,Siemens Healthcare,Erlangen,Germany)were used.On the initial MRI,abdominal wall edema was observed.Two mutually perpendicular abdominal lines were drawed on MR post-processing workstation,and the abdominal wall structures were divided into four areas.The widest range of abdominal wall edema was found in the middle and upper abdomen,and the abdominal wall edema score was used(0-4 points).In the human anatomy department of Wuhan university,three male gross specimens were cut off along the line of double nipples and the plane of the upper end of femur.And then cross-sectional specimens were made by means of a special cutter for cadavers.The interested areas were observed and photographed,and then the images were stored on personal computers.Student's t test or Mann-Whitney U test was used for comparison between quantitative data sets.Quantitative data of the three groups were compared using one-way analysis of variance(ANOVA).The Pearson ?2 test or Fisher's exact method was used to compare qualitative data groups.The correlation between abdominal wall edema score and the severity of AP was analyzed by Spearman rank correlation.The receiver operating characteristic(ROC)curve analysis of abdominal wall edema score was used to quantitatively predict the diagnostic capability for severe acute pancreatitis according to the 2012 RAC.Results(1)The demographic characteristics of a total of 211 hospitalized patients with AP were given as follows:119(56.4%)males and 92(43.6%)females,aged 52.9±16.5 years(20-94 years).According to the RAC 2012,there were 72 cases of mild acute pancreatitis(MAP)(34.1%),99 cases of moderately severe acute pancreatitis(MSAP)(46.9%),and 40 cases of severe acute pancreatitis(SAP)(19%).56.9%(120/211)of all AP patients presented with abdominal wall edema on the initial MR images.The incidence of abdominal wall edema was 16.7%(12/72),68.7%(68/99)and 100%(40/40)in the MAP group,the MSAP group and the SAP group,respectively.The incidence of abdominal wall edema was statistically different between the three groups(x2=83.42,P<0.001).The abdominal wall edema score was 1.3±0.5 points(1-2 points),2.5±0.9 points(1-4 points),and 3.3±0.7 points(2-4 points),respectively.The scores of abdominal wall edema were statistically different between the MAP,MSAP and SAP groups(F=32.3,P<0.001).Abdominal wall edema score was positively correlated with the severity of AP(R2=0.35,P<0.001).When abdominal wall edema score was? 3 points,the sensitivity and specificity for SAP were predicted to be 85%,and 65%,with AUC=0.786(95%CI:0.704,0.868,P<0.001).(2)On MRI,the involvement incidence of abdominal wall edema in 120 patients with AP was ranked as follows:the involvement of left posterior abdominal wall of 95.8%(115/120),right posterior abdominal wall of 84.2%(101/120),left anterior abdominal wall of 48.3%(58/120),and right anterior abdominal wall of 33.3%(40/120).MRI findings of anatomic spread pathways in 115 patients with left posterior abdominal wall involvement were five features,which we named R left posterior 1-R left posterior 5.Using CT multiplanar reconstruction,we found that the narrow channel of left posterior abdominal wall was at lateral edges of left quadratus psoas,and medial edges of tendons of left external oblique muscle/internal oblique muscle and abdominal transverse.It accounted for 64.5%(136/211)at the level of mid-part of L3 vertebral body to mid-part of L5 vertebral body,and 35.5%(75/211)at the level of lower-edge of L3 vertebral body to mid-part of L5 vertebral body.The narrow channel width of left posterior abdominal wall was of a diameter of 3 mm to 6.3 mm.In 58 patients with AP involving left anterior abdominal wall,there were two spread pathways for left anterior abdominal wall edema,which we named R left anterior 1 and R left anterior 2.The 101 patients with AP involving right posterior abdominal wall had five types of abdominal wall pathways,which we named R right posterior 1-R right posterior 5.Using CT multiplanar reconstruction,we found that the narrow channel of right posterior abdominal wall was at lateral edges of right quadratus psoas,and medial edges of tendons of right external oblique muscle/internal oblique muscle and abdominal transverse.It accounted for 68.7%(145/211)at the level of lower-part of L3 vertebral body to mid-part of L5 vertebral body,and 31.3%(66/211)at the level of upper-edge of L4 vertebral body to mid-part of L5 vertebral body.The narrow channel width of right posterior abdominal wall was of a diameter of 3 mm to 6 mm.In the 40 cases of AP involving right anterior abdominal wall,there were two spread pathways,which we named them R right anterior 1 and R right anterior 2.In addition,on MRI,21.6%(26/120)of AP patients with abdominal wall edema had belly button involvement.There were two spread pathways of edema in abdominal wall of belly button,which we named them R belly button 1 and R belly button 2.Moreover,ninety percent(108/120)of AP with abdominal wall edema were associated with posterior lumbosacral median subcutaneous edema.The posterior lumbosacral subcutaneous edema pathways included a narrow passage crossing the lateral border of quadrumius psoas to the posterior layer of thoracolumbar fascia,and passed through the reticular fiber bundle and superficial fascia connective tissue fiber bundles,and finally reached superficial fascia connective tissue fiber bundles and the deep fascia posterior layer of the thoracolumbar fascia.Conclusions Abdominal wall edema on MR images of AP is a common imaging sign.The incidence of abdominal wall edema increased in MSAP and SAP,and there were significant differences among three groups.Abdominal wall edema score was positively correlated with the severity of AP,and it has a better ability to diagnose SAP.Abdominal wall edema involved left posterior abdominal wall was most common in AP,and there were five pathways for the involvement of left or right posterior abdominal wall.There are "anatomical vulnerability sites" in corresponding anterior and posterior abdominal walls.Lumbosacral posterior subcutaneous edema is formed by connecting the superficial fascia reticular bundles to both sides of posterior abdominal walls,and it communicates with Scarpa fascia to form annular pathways of abdominal wall edema. |
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