RadiologyGASTROINTESTINAL SYSTEMBy: Dr. KawaTyped by:Bnar J. AhmedPaywand M. AliRako AbdulqadirRanko B. MajeedSuren Y. Hama BaqiDesign: Rzgartmi.CONTENTSCONTENTS TOC o "1-3" p " " h z u CONTENTS PAGEREF _Toc295592494 h 2ESOPHAGUS PAGEREF _Toc295592496 h 3Normal barium swallow PAGEREF _Toc295592497 h 3Abnormal barium swallow: PAGEREF _Toc295592498 h 3Stricture: PAGEREF _Toc295592499 h 3Filling defect PAGEREF _Toc295592500 h 4Dilatation of esophagus PAGEREF _Toc295592501 h 5Varices PAGEREF _Toc295592502 h 5Esophagus web PAGEREF _Toc295592503 h 5Diverticula PAGEREF _Toc295592504 h 5Esophageal atresia PAGEREF _Toc295592505 h 5Candidiasis PAGEREF _Toc295592506 h 5STOMACH AND DUODENUM PAGEREF _Toc295592507 h 6Normal barium meal: PAGEREF _Toc295592508 h 6Gastroscopy: PAGEREF _Toc295592509 h 6Indications: PAGEREF _Toc295592510 h 6Abnormal barium meal findings PAGEREF _Toc295592511 h 6Filling defects (intarluminal, intramural, extramural) PAGEREF _Toc295592512 h 7GU PAGEREF _Toc295592513 h 7narrowing PAGEREF _Toc295592514 h 8Thick gastric mucosal folds PAGEREF _Toc295592515 h 8Gastric outlet obstruction PAGEREF _Toc295592516 h 8Gastritis PAGEREF _Toc295592517 h 9Hiatus hernia PAGEREF _Toc295592518 h 9DU PAGEREF _Toc295592519 h 9Upper GI bleeding: PAGEREF _Toc295592520 h 9SMALL INTESTINE PAGEREF _Toc295592521 h 9Normal Ba follow through: PAGEREF _Toc295592522 h 10Enteroclysis: PAGEREF _Toc295592523 h 10Abnormal Ba follow through: PAGEREF _Toc295592524 h 10Crohn’s disease: PAGEREF _Toc295592525 h 10Tb: PAGEREF _Toc295592526 h 11Lymphoma: PAGEREF _Toc295592527 h 11Malabsorption: PAGEREF _Toc295592528 h 11Definite Dx PAGEREF _Toc295592529 h 11Signs: PAGEREF _Toc295592530 h 11Disaccharidase deficiency: PAGEREF _Toc295592531 h 11Acute SI obstruction: PAGEREF _Toc295592532 h 12LARGE INTESTINE PAGEREF _Toc295592533 h 12Indications for colonoscopy: PAGEREF _Toc295592534 h 12Normal Ba enema: PAGEREF _Toc295592535 h 12Abnormal Ba enema: PAGEREF _Toc295592536 h 12Narrowing of the lumen: PAGEREF _Toc295592537 h 12Dilatation of colon: PAGEREF _Toc295592538 h 13Filling defects in the colon: PAGEREF _Toc295592539 h 13Ulceration of colon: PAGEREF _Toc295592540 h 13Tumors of the colon: PAGEREF _Toc295592541 h 14Polyp PAGEREF _Toc295592542 h 14Carcinoma PAGEREF _Toc295592543 h 14Hirschsprung’s disease PAGEREF _Toc295592544 h 15Idiopathic megacolon PAGEREF _Toc295592545 h 15Acute Bleeding (S and L bowel) PAGEREF _Toc295592546 h 15HEPATOBILIARY SYSTEM PAGEREF _Toc295592547 h 15Methods of imaging: PAGEREF _Toc295592548 h 15Normal liver: PAGEREF _Toc295592549 h 15Liver masses: PAGEREF _Toc295592550 h 16Masses include the following: PAGEREF _Toc295592551 h 16Liver trauma: PAGEREF _Toc295592552 h 17Liver cirrhosis and portal hypertension: PAGEREF _Toc295592553 h 17Fatty degeneration of the liver: PAGEREF _Toc295592554 h 18Biliary system PAGEREF _Toc295592555 h 18Ultrasound PAGEREF _Toc295592556 h 18CT PAGEREF _Toc295592557 h 18Radionuclide scan: PAGEREF _Toc295592558 h 18ERCP: PAGEREF _Toc295592559 h 19Others PAGEREF _Toc295592560 h 19Gall stones and chronic cholecystitis PAGEREF _Toc295592561 h 19Plain film: PAGEREF _Toc295592562 h 19U/S: PAGEREF _Toc295592563 h 19Acute cholecysitis PAGEREF _Toc295592564 h 20U/S: PAGEREF _Toc295592565 h 20Jaundice: PAGEREF _Toc295592566 h 20US shows: PAGEREF _Toc295592567 h 20CT-scan: PAGEREF _Toc295592568 h 20Others PAGEREF _Toc295592569 h 21SPLEEN AND PANCREAS PAGEREF _Toc295592570 h 21Spleen: PAGEREF _Toc295592571 h 21Pancreas: PAGEREF _Toc295592572 h 21Pancreatic masses: PAGEREF _Toc295592573 h 21Adenocarcinoma of pancreas PAGEREF _Toc295592574 h 21Acute pancreatitis PAGEREF _Toc295592575 h 22Chronic Pancreatitis PAGEREF _Toc295592576 h 22Pancreatic trauma PAGEREF _Toc295592577 h 22PERITONEAL CAVITY AND RETROPERITONEUM PAGEREF _Toc295592578 h 23Peritoneal cavity PAGEREF _Toc295592579 h 23Ascites PAGEREF _Toc295592580 h 23Peritoneal tumors PAGEREF _Toc295592581 h 23Intra peritoneal abscess PAGEREF _Toc295592582 h 23Retroperitoneum PAGEREF _Toc295592583 h 24Retroperitoneal organs: PAGEREF _Toc295592584 h 25Retroperitoneal Lymphadenopathy PAGEREF _Toc295592585 h 25Adrenal glands PAGEREF _Toc295592586 h 25Retroperitoneal tumor PAGEREF _Toc295592587 h 27Aortic aneurism PAGEREF _Toc295592588 h 27Retroperitoneal hematoma PAGEREF _Toc295592589 h 27Retroperitoneal abscess and psoas abscess PAGEREF _Toc295592590 h 27<br />ESOPHAGUS<br />Plain film very dilated- opaque FB<br />Barium swallow is the contrast examination to visualize the esophagus <br />Oblique view to project the esophagus clear of the spine. <br />Take films under fluoroscopy ... full of barium to show outline. <br />Empty of barium to show the mucosal pattern. <br />Normal barium swallow <br />
Full of barium smooth outline
Empty of barium folds of mucosa( three or four long straight parallel lines)
Diffuse esophageal spasm if associated with dysphagia
Abnormal barium swallow:<br /> look for:<br />Stricture, filling defect, dilatation, varices, esophageal web , diverticula, esophageal atresia, candidiasis.<br />Stricture:<br /> is an important cause of dysphagia. <br />Causes: CA, peptic stricture, achalasia and corrosive stricture <br />Distinction between these depends on site, shape, length, soft tissue mass.<br />CA <br />Usually involves a full circumference to form stricture and rarely arises from only one wall.<br />As a rule: CA esophagus usually presents as a stricture and not as a filling defect or mass.<br />Radiological feature <br />
Achalasia : Is a failure of relaxation of LES <br />Radiological feature <br />Smooth, tapering narrowing, always at the lower end of esophagus, dilatation of esophagus above it, absent peristalsis, food residues are present, consolidation and bronchiectasis in the lung, absent stomach gas bubble(usually), but not diagnostic <br />Corrosive stricture <br />Long stricture, smooth, tapering ends, may be irregular <br />Filling defect <br />(Intraluminal, intramural, extramural)<br />
Intraluminal usually food lump, look for associated stricture
Smooth, Rounded indentation<br /> But CA (irregular filling defect, usually presents as stricture) <br />
CA of bronchus<br />Mediastinal LN enlargement <br />Aortic aneurysm <br />Anomalous Rt subclavian artery (short, smooth narrowing, crosses behind the upper esophagus)<br />Dilatation of esophagus <br />Types (Obstructive and non obstructive) <br />Dilatation+ obstruction is associated with stricture <br />The patient with CA usually presents with dysphagia (stricture) before the esophagus becomes dilated <br />Markedly dilated esophagus indicates long standing condition E.g. achalasia or benign stricture <br />Dilatation with out obstruction occurs in scleroderma (no obstruction, no peristalsis, dilatation)<br />Varices <br />Appear as a lucent, tortuous, worm like filling defects with distort a mucosal pattern, so that a folds are no longer parallel do endoscopy.<br />Esophagus web<br /> Web is a thin shelf like projection arising from anterior wall of the cervical portion of the esophagus, combination of web+ dysphagia+ iron deficiency anemia Plummer Vinson syndrome.<br />Diverticula<br />Are saccular out pouchings which are often seen as chance findings in the intrathoracic portion of the esophagus, pharangeal pouch of zenker’s diverticulum is important <br />
Esophageal atresia <br /> Several different types exist, commonest is in upper part of esophagus ending blindly, the lower part has fistula with tracheobronchial tree ..pass soft tube into the esophagus coiling, holds up.<br />Candidiasis<br />Severely ill patient, in immunocompromised, it causes mucosal ulceration which is seen as fine irregularities projecting from the lumen of the esophagus.<br />STOMACH AND DUODENUM<br />Barium meal is a contrast study of the stomach and duodenum, 200 ml of barium at least 6hr fasting prior to examination both erect and lying flat <br />Double contrast examination (barium and gas) the stomach is distended with a gas producing agent + I.V injection of short acting MM relaxant to provide better mucosal detail.<br />Normal barium meal:<br />Check each part of the stomach and duodenum <br />
No abnormal narrowing present
The outline of lesser curve of stomach is smooth with no filling defects or projection
Greater curve is nearly always irregular due to prominent mucosal folds
The Duodenal cap or bulb is nearly triangular in shape + short pyloric canal
The duodenum forms a loop around the head of pancreas to reach the duodenojejunal flexture
Diverticula of the end part of the duodenum is common finding
Gastroscopy:<br />Gastroscopy and Ba meal are complementary <br />Indications:<br />
Gastric outlet obstruction <br />In most patient barium rapidly leaves the stomach to enter the duodenum, but in others this only occurs after the patient has been lying down on the right side for several min, in gastric outlet obstruction 50% of the barium leaves the stomach after 4 hr, or even 24 hr stomach will be large, contains food residues.<br />Causes <br />
Pyloric stenosis (In infant is the commonest cause)
Dx. U/S, clinical <br />Gastritis <br />Erosive gastritis alcohol, aspirin <br />Double contrast barium meal … erosions appear as:<br />Small, shallow collections of Ba, surrounded by a radiolucent halo due to edema .<br />Hiatus hernia <br />Types:<br />Sliding and rolling (para esophageal)<br />
Sliding (more common)
GE junction+a portion of stomach are above the diaphragm<br />Incompetent cardiac sphincter, so reflux occurs and may cause esophagitis, ulceration and peptic stricture.<br />
Fundus of the stomach herniates <br />GE junction in normal position and competent cardiac sphincter<br />DU <br />Rarely malignant could be bulbar (common) or postbulbar <br />Radiological features: <br />
No need for follow up by barium meal not possible to comment, it doesn’t undergo malignant changes <br />Upper GI bleeding:<br />do gastroscopy <br />Causes:<br />PU, gastric erosions, varices, CA <br />SMALL INTESTINE<br />Standard contrast ex. Is Ba follow through, an alternative is enteroclysis (small bowel enema).<br />Normal Ba follow through:<br />Position: the small bowel occupies the central and lower abdomen, usually framed by colon. The diameter is normally <25mm. Its appearance depends on the diameter of bowel, when distended the folds seen as lines traversing the bowel called valvulae conniventes, when contracted the folds lie longitudinally and assume feathery appearance when relaxed.<br />Enteroclysis:<br />Distends the bowel and gives excellent mucosal details. The disadvantage is it requires intubation with a nasoduodenal tube, Ba is injected through the tube followed by water or cellulose.<br />This technique is used in cases with structural deformities, e.g. Crohn’s disease or tumors, but not used in cases with malabsorption syndrome.<br />Abnormal Ba follow through:<br /> look for:<br />
Dilatation, which indicates either malabsorption, paralytic ileus or small intestinal obstruction. A value of 30mm is definitely abnormal, valvulae conniventes become clearly visible.
Mucosal abnormality, mucosal folds thicken in malabsorption, oedema, hemorrhage in the bowel wall, and when inflamed or infiltrated.
Narrowing, normal narrowing is caused by peristalsis, they are smooth, concentric, transient with normal mucosal folds. When there is stricture, it’s caused by crohn’s disease, TB, lymphoma, they don’t contain normal mucosal folds and bowel dilates proximally.
Ulceration, may appear shallow or deep. Ulceration is seen in Crohn’s disease, TB, lymphoma... Cobble stone appearance may be seen due to ulceration and mucosal oedema.
Alteration in position, in congenital malrotation or displacement by a mass.
Crohn’s disease:<br />Is a disease of unknown cause, characterized by:<br />
Localized area of non-specific chronic granulomatous inflammation.
LARGE INTESTINE<br />Standard ex of the LI are: Ba enema (single contrast or double contrast), endoscopy (either sigmoidoscopy for rectum, or colonoscopy which is complementary).<br />Indications for colonoscopy:<br />
Inspecting and taking biopsy of abnormalities seen in Ba enema.
Patient with persistent symptoms with a normal Ba enema.
Screening of a patient with a strong family Hx of colonic Ca.
Assessing the extent of ulcerative colitis and crohn’s disease.
Normal Ba enema:<br />Length of colon is very variable, there are redundant loops especially in sigmoid and transverse colon. Caecum is usually located in the right iliac fossa, but may be under the right lobe of liver or even in central abdomen. Haustrations usually recognized but may be absent in the descending colon and sigmoid colon, the outline of distended colon is smooth.<br />Abnormal Ba enema:<br />Narrowing, dilatation, filling defects, diverticulae, ulceration, displacement of the colon.<br />Narrowing of the lumen:<br /> causes are: spasm, stricture, and compression by an extrinsic mass.<br />
Spasm: is smooth concentric narrowing, it can be abolished by i.v. mm relaxative e.g. buscopan.
Stricture: main causes are Ca, Diverticular disease, crohn’s disease, ischemic colitis. Rare causes are TB, lymphogranuloma venerum, amoebiasis and radiation fibrosis.
Should be born in mind:<br />
Neoplastic strictures have shouldering edges, irregular lumen and > 6cm in length.
Benign strictures have tapered ends, smooth outline of any length.
Ulceration maybe seen in strictures due to crohn’s dis.
Stricture due to diverticular disease is accompanied by other signs.
Extrinsic compressions have smooth narrowing from one side only, often displace the colon. Smooth indentation on the caecum maybe seen with appendicular mucocele, appendicular abscess, and inflammatory mass and in crohn’s.<br />Dilatation of colon:<br />This is difficult to assess especially double contrast study which involves distention of colon and depends on the amount of Ba and air introduced… causes are:<br />
Filling defects in the colon:<br /> Intra luminal, intra mural, and extra mural.<br />Localized filling defects: CA, polyp, feces, the feces have no attachment to the wall and completely surrounded by Ba or air, more freely… so preparation of the patient before Ba enema is needed.<br />Multiple smooth filling defects in the wall (intramural) are caused by hemorrhage of the wall, oedema, or pneumatosis. Intussusception is a unique type.<br />Ulceration of colon:<br />They are small projections from the lumen into the wall of the bowel. This results in fuzzy or shaggy appearance. <br />Causes:<br />
Tumors of the colon:<br />Polyp<br /> means a small mass of tissue arising from the wall of the bowel, projecting into the lumen. They are either sessile or pudenculated, single or multiple, neoplastic, inflammatory or developmental, benign or malignant. They are best examined by a double contrast Ba-enema.<br />Features suggesting malignancy:<br />
Carcinoma<br />Sites are rectosigmoid and cecum.<br />Types are annular carcinoma, polypoid carcinoma or fungating.<br /> Annular carcinoma shows irregular stricture with shouldered edges, rarely more than 6cm in length.<br /> Polypoid or fungating carcinoma -> irregular filling defects projecting into the lumen.<br />CT scan is alternative to Ba-enema as:<br />
Hirschsprung’s disease<br /> Is due to absence of ganglionic cells, usually in sigmoid or rectosigmoid junction. The aganglionic segment, usually the rectum, is either normal or small at Ba-enema and diagnosis depend on recognizing the transitional zone from the normal, or reduced calibred colon to the dilated colon. The colon is not wasted out before the Ba-enema as water intoxication occurs.<br />Idiopathic megacolon<br />Chronic constipation is the cause, Ba- enema shows both rectum and colon are dilated and contain large amounts of feces; the rectum is large in size.<br />Acute Bleeding (S and L bowel)<br />Meckel’s diverticulum in children may lead to unexplained bleeding. For bleeding we do:<br />
High uptake is seen in stomach and in any gastric mucosa within a meckle’s diverticulum.<br />Ba-enema should be avoided as a first examination.<br />HEPATOBILIARY SYSTEM<br />Methods of imaging:<br />Non invasive like plain X-ray, contrast study, ultrasound, CT scan, MRI, radionuclide.<br />Invasive methods like PTC, ERCP, and selective arteriography.<br />Ultrasound particularly useful for GB disease, cyst, abscess and perihepatic fluid collection.<br />CT, MRI for mass lesion detection.<br />Normal liver: <br />Ultrasound of normal hepatic parenchyma include: <br />
Interspersed with bright echoes of portal triad and echo- free areas of large hepatic veins and portal vein.
CT scan: I.V contrast often given to increase density of normal liver parenchyma and to produce a different density between the normal parenchyma and the lesion, which enhance poorly except hemangiomas.<br />Radionuclied Liver image: almost completely replaced by ultrasound, CT, MRI.<br />MRI: is used as a problem-solving technique to give additional information to ultrasound and CT.<br />Liver masses:<br />Ultrasound, CT, MRI decide whether mass is present or not, and differential diagnosis can be suggested, but Biopsy is the definitive diagnosis. <br />Masses include the following:<br />
Liver neoplasm: either primary (hepatoma, lymphoma) or secondary’s from the stomach, colon, pancreas, breast, lung) . Secondaries are more common than primaries.
As a rule most pathologies are bright on T2, dark on T1 except fat.<br />Liver abscess:<br />Structurally it’s similar to cysts, but usually they can be distinguished, as they have thicker wall, fluid centers, more regular and more obvious.<br />At ultrasound a layer of necrotic debris may be seen within the abscess. Occasionally chronic abscess calcify.<br />At CT scan attenuation value usually higher than water, but may be similar to water.<br />Note: abscess can usually be distinguished from necrotic tumors at Ultrasound, CT, MRI, but the clinical situation should aid in making distinction. Aspiration under ultrasound guidance is invariable.<br />Liver trauma:<br />CT scan is the best technique as it surveys other organ injuries like kidney or spleen. Injuries could be either parenchymal laceration or subcapsular hematoma. <br />CT scan shows:<br />
Differential diagnosis: artifact, pre-existing mass lesion.<br />Liver trauma is the commonest abdominal injury that leads to death. <br />Liver cirrhosis and portal hypertension: <br />Causes of portal hypertension are:<br />
At ultrasound the texture of liver is diffusely abnormal.
At CT scan normal, until late in the disease.
Portal venography: assess the patency of the portal vein. Contrast is injected into the celiac axis, splenic artery and superior mesenteric artery.<br />Treatment is portocaval anastomosis. And TIPSS (Transjugular Intrahepatic Portosystemic Stent Shunt).<br />Fatty degeneration of the liver:<br />Is frequent finding, either whole liver affected or sections.<br />Ultrasound shows: <br />
Increased echogenecity, called bright liver.
Similar to that of centre of the kidney which is echo-complex.
CT scan:<br />
Vessels are relatively highly attenuated structures against a background of low-density parenchyma.
MRI: is useful in problem cases, shows characteristic set of signal for fat. <br />Biliary system<br />Ultrasound<br />US is the best method of investigation because it is:<br />
Excellent for confirming or excluding BD dilatation.
CT<br />CT can also show these, but U/S is less costy and gives more information.<br />as the GB is a fluid filled organ. It is particularly amenable for U/S examination, because it is important that GB should be full of bile and the patient asked to fast, to prevent GB contraction. The normal GB wall is thin. GB wall is thickening in acute & chronic cholecystitis. Gall stone greater than 1-3 cm can be seen.<br />It is usually imposible to diagnose cystic duct obstruction by U/S, so we use radionuclide. The CBD & common hepatic duct can be visualized in almost all patients, but the lower end of CBD is obscured by the duodenum.<br />Radionuclide scan:<br /> IDA (imino-diacetic acid) labeled with Tcm99 is used. The main uses are in:<br />
The patient should fast for 4 hours prior to injection. Hepatic excretion occurs despite high serum bilirubin levels, so these agents can be used in jaundiced patients. Normally the GB, CBD, duodenum & SI are seen within first hour, confirming the patency of both cystic duct & CBD. If we see CBD, duodenum, SI, within first hour, but GB not visualized so cystic duct obstruction considered.<br />ERCP: <br />indications:<br />
To determine the cause of jaundice in patient with large duct obstruction.
Unexplained abdominal pain thought to be biliary in origin when other investigations have been equivocal.
To demonstrate CBD in patients undergoing laparoscopic cholecystectomy especially when history & biochemical investigation suggest stone in CBD.
Others<br />Oral cholecystography: iodine is used, now replaced by U/S.<br />PTC: alternative to ERCP, the patient usually jaundiced, done in LA.<br />MRCP: no need for contrast.<br />Gall stones and chronic cholecystitis<br />Are frequent findings, especially in middle aged females. There is cause of recurrent upper abdominal pain, but presence of stone does not necessarily mean the pain is due to stone. 20-30% are radio-opaque.<br />Plain film:<br />
Calcified sludge with the GB, known as “milk of calcium bile”
Strongly echogenic foci seen in dependent portions of GB.
Posterior shadowing behind the stone is very important as it is not seen in polyp.
Polyp of GB is small, not neoplastic, it is aggregation of cholesrol.<br />Although U/S is accurate for diagnosis of gall stones, is less reliable for diagnosis of CBD stones.<br />In adenomyomatosis, the GB wall is thickened and may show altered echogenesity of the wall, due to Rokitansky- Aschoff sinuses (small projections of the lumen into the wall).<br />Acute cholecysitis<br />U/S:<br /> usually detect<br />
In hepatobiliary radionuclide scan actually answer the question “is the cystic duct patent?” mostly obstructed in acute cholecystitis.<br />Jaundice:<br /> imaging used to diagnose the obstructive causes of jaundice, which are:<br />
Dilated intrahepatic biliary ducts seen as serpentine structures, parallel to the portal vein, called double-channel sign.
CBD lies just infront of the portal vein and is dilated when more than 7 mm in diameter.
If there is large duct obstruction, the biliary tree will be dilated down to the level of obstruction.
CT-scan: <br />Two points should be appreciated:<br />
Substantial dilatation of the common hepatic duct and CBD may be present with only minimal dilatation of the intrahepatic ducts.
The intrahepatic biliary tree may not dilate at all, within the first 48 hours after the obstruction.
Others<br />ERCP or PTC may be used.<br />Radionuclide scan to show the obstruction.<br />SPLEEN AND PANCREAS<br />Spleen:<br />By U/S there is homogenous appearance with the same echo density as the liver.<br />CT and MRI are excellent for splenic masses (cysts, abscess, lymphomas) much common than metastasis.<br />Conditions that lead to splenic enlargement with no change in splenic texture on U/S and no change in density on CT:<br />
Adenocarcinoma of pancreas<br />Adenocarcinoma of pancreas: in the head jaundice.<br />In the body and tail enlargement pain.<br />Measurement is not useful in diagnosing masses.<br />The important signs in both CT and U/S are: <br />
Focal mass deforming the outline of the gland.
Irregular obliteration of the fat around the pancreas.
If contrast used on CT, the tumor is relatively low in density than normal pancreatic tissue.
Acute pancreatitis<br />Diagnosis is clinical and biochemical.<br />For complication, imaging is beneficial. Clinically, there is abdominal pain, fever, vomiting, leukocytosis.. Biochemically, increased serum amylase. <br />The findings on CT and U/S vary with the amount of hemorrhage, necrosis and suppuration… the signs are:<br />
Pancreas usually enlarged, often diffusely enlarged.
Enlargement… Either focal (rare and mistaken with CA) or general enlargement.
Atrophy: is non specific sign as it occurs in elderly and distal to CA... Maybe focal or general.
Pancreatic duct may enlarge and irregularity seen ERCP shows generalized irregular dilatation of the duct system.
Pancreatic trauma<br />Pancreatic trauma is uncommon, but serious. CT is the best. Ex. Laceration, hematoma…<br />PERITONEAL CAVITY AND RETROPERITONEUM<br />Peritoneal cavity<br />Ascites<br />U/S, CT and MRI can demonstrate very small amount of ascites more little than the amount needed for clinical or plain film detection, but no imaging technique can distinguish the nature of the fluid (exudates or transudate).<br />
In supine position fluid collect in dependant portion (pouch of doglas ->anterior to upper rectum), (Morrison’s pouch in space anterior to Rt kidney) and in para colic gutter.
If large amount of fluid are present, fluid will be seen throughout the peritoneal cavity and stomach or ………… may be seen floating in the ascites.
At CT scan, ascites is of lower density than liver, spleen and kidney.
One of the easiest site to see ascites is near the liver, a uniform band of low density can identify with liver and diaphragm
Ascites cannot collect posterior to the upper part of liver because of the peritoneal reflection forming the so called bare area.
When loculated ascites is seen as discrete collection of fluid. Loculated lesion may not be distinguishable from fluid in abscess because the density of infected and uninfected fluid can be identical.
On U/S, ascites seen as echofree regions and often in bowel dilatation with excess gas.
Peritoneal tumors<br />Most common tumor is metastasis from abdominal or pelvic tumors, especially CA of ovary.<br />U/S and CT may show only ascites or peritoneal nodule in ovarian carcinoma numerous nodules may coalesce to form what is called omental cake.<br />Intra peritoneal abscess<br />
May follow perforation of bowel or biliary tract.
Either sub hepatic, Subphrenic, Para colic and pelvic.
CT<br />CT is particularly informative in obese patient because fat surrounds important structures. It’s difficult in non obese specially children.<br />In CT look for:<br />
Complete outline of aorta and inferior vena cava should be clearly visible throughout their length except when inferior vena cava passes through liver. The aorta is round in cross section and measures 2-2.5 cm and the IVC is round to oval.
There is usually fat containing space to left of aorta which is a good area to look for Lymphadenopathy. The only structure other than LN to be seen in this space is left renal vein.
The psoas muscles are seen as symmetrical rounded structures.
US<br />Retroperitoneal fat is very echoreflective. Aorta and IVC easily identified, also enlarged LN, normal adrenal gland rarely visible.<br />MRI<br />Provide little advantage in retroperitoneal ∆.<br />Retroperitoneal Lymphadenopathy<br />
The normal Para aortic LN vary in size from invisible to 1cm in retrocrural area the upper limit of normal is 6 mm.
Size is the only criterion of abnormality normal, inflammatory and neoplastic nodes usually have the same features and texture at CT, US & MRI.
Enlargement of over 2 cm is almost always neoplastic, but less than 2cm may be inflammatory or neoplastic.
Adrenal glands<br />
The normal adrenal glands are thin, bilobed structure surrounded by fat.
Non functional adenoma larger than 3cm are rare, may be due to metastasis or primary adrenal carcinoma. The common malignant adrenal tumor is neuroblastoma.
Metastasis are frequently bilateral, also adrenal abscess and hemorrhage are usually bilateral and indistinguishable at ct.
Retroperitoneal tumor<br />
The commonest one is liposarcoma and fibrosarcoma.
They appear as mass on CT, US, or MRI sometimes the edge of the mass is well defined but sometimes invade the surroundings.
Aortic aneurism<br />CT, US, and MRI used for diagnosis<br />
Both CT and US used as a screen exam for aortic aneurism in older men. CT + US used to measure diameter of aortic aneurism and identify the wall and any lining thrombus you can also see any retroperitoneal bleeding from an aneurism at CT. At CT aneurism >6cm are in serious danger of rupture.
At angiography the outline of aortic lumen seen this is due to thrombus and not the wall that form the outline.
Aortography is of limited use in assessing the diameter although it is a good technique for the aorta above the aneurism.
Plain film can also show the aneurism but only if substantial calcification is present in the wall.
Retroperitoneal hematoma<br />
Usually due to trauma or bleeding from an aortic aneurism, it’s sometimes spontaneous in patient on anticoagulant therapy or bleeding tendency.