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1 2011 연세대학교의과대학소화기학연수강좌 임상에서유용한복부 CT, MRI 판독법과최신기법 연세대학교의과대학영상의학교실 김경아 복부에서는복통을호소하는응급상황이흔히발생하게된다. 이럴경우지체없는빠른진단과적절한치료방향을결정하는것이무엇보다요구된다. 일차적으로환자가내과적질환인지또는외과적질환으로수술적치료를필요로하는지판단하는것이필요하다. 이러한판단에는임상의사의병력청취나신체검사가중요하지만최근영상의학검사가중요한진단수단으로역할을하고있다. 흔히복통을유발하는대표적복부질환의영상소견에대해살펴보겠다. Acute Appendicitis 의역할 US 상애매한경우, 체형이커서 US 검사가어려운경우, appendix가 retrocecal 위치에있는경우등에서 CT 시행. Distended fluid-filled structure, diameter >7 mm, circumferential and symmetric wall thickening and enhancement, periappediceal fat stranding, cecal wall thickening, appendicolith Diverticulitis 의역할 Acute appendicitis와증상이유사하여감별에도움이됨. Diverticuli, adjacent bowel wall thickening, fat infiltration around diverticuli, abscess, normal appendix 56

2 김경아 : 임상에서유용한복부 CT, MRI 판독법과최신기법 Epiploic Appendicitis 1. Cause Torsion or venous thrombosis of appendages 2. Location Rectosigmoid (57%)> ileocecal (26%)> ascending colon 3. CT Well circumscribed fatty mass with hyperattenuating streaks around colon, no or minimal colon wall thickening Peptic Ulcer Perforation Varying amount of free air, peritonitis, free spillage of gastric and duodenal contents, perigastroduodenal soft tissues, interruption of enhanced gasdtroduodenal wall Intestinal Obstruction 1. 원인 Adhesive band, hernia, inflammatory bowel disease, tumor, bezoar, GB stone, etc 의역할 1) 장폐쇄의심시가장빠르고비침습적으로시행할수있음. 2) 장의허혈과폐쇄의원인을알기위해서는 IV 조영제를주입한후검사 3) High grade obstruction 시높은민감도, 특이도, 정확도 4) 진단, 폐쇄정도, transitional zone 확인, complication 유무확인 3. Intestinal obstruction - 소장폐쇄는장폐쇄의 60 80% 차지, 대장폐쇄에비해 4 5배호발 1) CT finding (1) Bowel distension ( 소장직경 3 cm 이상 ), bowel wall thickening, abnormal wall enhancement, transitional point, small bowel feces, ascites, pneumatosis, portomesenteric gas (2) Closed-loop obstruction - 두곳의폐쇄지점사이에끼인장분절을말하고, adhesive band에의한경우가가장흔하고 hernia에서도발생. CT상 C-자혹은 U-자형, coffee bean 모양의늘어난장관이보이며 torsion 부위에 mesenteric vessel의 converging이동반되며, whirl sign을보인다. 57

3 2011 연세대학교의과대학소화기학연수강좌 Liver Abscess - Pyogenic Abscess, Amebic Abscess finding of pyogenic abscess Fluid collections with enhancing wall, transient segmental or wedge-shaped enhancement of hepatic parenchyma on arterial phase, cluster sign, round or lobular contour, central gas, air-fluid level finding of amebic abscess Peripheral round or oval areas of low attenuation (10-20HU), unilocular or multilocular, concomittent extrahepatic abnormalities including right-sided pleural effusion, perihepatic fluid, gastric or colonic involvement Acute Hepatitis 1. Non-specific imaging finding 2. 영상검사는폐쇄성황달, 미만성간전이혹은간경변등을배제하기위해시행 3. CT finding: hepatosplenomegaly, heterogenous parenchymal enhancement, periportal edema, GB edema, enlarged LNs along hepatoduodenal ligament Acute Cholecystitis GB stone (90%), GB wall thickening, pericholecystic fluid, pericholecystic fat stranding, subserosal edema, GB distension, GB bed에 transient hyperemia, sonographic Murphy s sign 2. MRI Heavily T2WI의 MRCP 상 radiolucent GB stone detection에 CT보다우월, cystic duct나 GB neck의 stone demonstration에우월 3. Emphysematous cholecystitis GB lumen/wall gas, pericholecystic tissues로의 gas spillage, free air (GB perforation) 4. Hemorrhagic cholecystitis Ordinary acute cholecystitis + intraluminal hematoma, increased bile density, fluid-fluid level 5. Gangrenous cholecystitis Intraluminal membranes, lumen 내 hematoma, irregular/abscent wall, pericholecystic abscess, GB lumen/wall gas, irregular or lack of GB wall enhancement 58

4 김경아 : 임상에서유용한복부 CT, MRI 판독법과최신기법 6. GB perforation GB wall defect, GB lumen 바깥의 GB stone, pericholecystic abscess (subacute), cholecystoenteric fistula (chronic) Choledocholithiasis 1) Sensitivity 65% to 88% 2) CT: slightly hyperdense GB stones on precontrast scan, a target sign (central density with surrounded by hypoattenuating bile), ductal dilatation, abrupt termination of duct without visible surrounding mass 2. MRCP 1) Sensitivity %, specificity 90%, accuracy 89 97% 2) MRCP: well-circumscribed low SI filling defects in biliary tract 1. 영상검사 Acute pancreatitis 진단과중증도예측, 합병증진단 Acute Pancreatitis 1) Normal-appearing gland (mild form) 2) Pancreatic swelling, shaggy and irregular contour, slightly hypoenhancing heterogenous parenchyma, peripancreatic fluid, peripancreatic fat stranding, thickening of pararenal fascia 3) Intrapancreatic or extrapancreatic fluid collection, pancreatic pseudocyst (4주이후 ), patchy areas of absence of enhancement, peripancreatic abscess 4) CT severity index (CTSI) in acute pancreatitis a. Grade of acute pancreatitis Score A Normal pancreas 0 B Focal or diffuse pancreatic enlargement 1 C Peripancreatic inflammation 2 D One perihepatic fluid collection 3 E Two or more fluid collection 4 b. Parenchymal necrosis No necrosis (homogenous contrast medium uptake) 0 Less than 30% % 4 Greater than 50% 6 CTSI a+b 59

5 2011 연세대학교의과대학소화기학연수강좌 5. MRI 정상췌장이외분비선의높은단백질함량에의해 T1WI에서높은신호강도를보여염증시저신호강도발견에민감, T1WI fat suppressed images에서 high SI의존재는 hemorrhagic necrosis나 proteinaceous exudates 등에의한신호강도변화 CT 검사의기법 - Bowel 중심 gastrography 1) 전처치 : overnight fasting, 검사 10 15분전에 spasmolytic agent 2) Scan position: supine, prone, LPO, RPO 3) 영상재구성 (1) Multiplanar reconstruction (MPR): 2차원영상을 Z축방향으로쌓아놓고, 임의의단면으로절단한후그절단면을보여주는것 (2) Maximum (MIP) 혹은 minimum intensity projection (minip): 이차원영상을 Z축방향으로쌓아놓은후체적데이터를관통하는투사선 (projection line) 을따라만나는모든 pixel값중가장밝은값 (MIP) 혹은가장어두운값 (minip) 을취하여이차원평명에투사하는방식, 대조도높아작은구조물도잘볼수있음 (3) Surface shaded display (SSD) 기법 : 일정체적테이터내에미리지정한역치값이상의 CT값 (HU) 을가진 pixel만을취해연결하여표면을구성한후가상의인공광원을비춰관찰자로반사되어들어오는광량에비례해표면에그림자를입힘으로써입체감을부여하는방식 (4) Volume rendering 기법 : 전체데이터의 histogram을얻고각조직의 opacity, brightness, color 등여러 parameter 를달리적용하여그적용된값의합을보여주는방식으로체적내모든데이터가재구성된최종영상에서로다른가중치로기여함. 2. Small bowel CT - CT enterography, CT enteroclysis 1) CT enterography: 소장영상을위해적절한내강확장을확보하기위해다량의조영제를마시게하고장운동을감소시키는약제투여, 조영제는 1,200 1,500 ml를검사 45 75분전부터투여하고, 적절히나누어 10 25분간격으로섭취하고약 cc 정도를검사 5분전에섭취 2) CT enteroclysis: 카테터를 fluoroscopic guidance 하에 descending duodenum이나 duodenojejunal junction까지삽입후 electronic pump로 ccmin으로 1,500 ml 가량의경구조영제를투여한후 CT를시행한다. 3. CT colonography 1) 전처치 (polyethylene glycol, sodium phosphate, magnesium citrate, bisacodyl 등 ) 후대장내의잔변에 radiopaque 한조영제로표지함. 검사전에 CO 2 주입하여 colonic distension 시켜 prone, supine position에서각각 CT scan 시행 60

388 The Korean Journal of Hepatology : Vol. 6. No COMMENT 1. (dysplastic nodule) (adenomatous hyperplasia, AH), (macroregenerative nodule, MR

388 The Korean Journal of Hepatology : Vol. 6. No COMMENT 1. (dysplastic nodule) (adenomatous hyperplasia, AH), (macroregenerative nodule, MR 6 3 2000 ; 387-392 (3) Dysplastic Nodule Young Nyun Park, M.D., Chanil Park, M.D. Department of Pathology, Yonsei University College of Medicine BRIEF HISTORY 56. AST/ALT 72/73 IU/L, total bilirubin 0.7