gastrointestinal imaging Flashcards
- imaging techniques of GIT
- skiagraphy (normal x-ray ) : hernias, diverticula, fistulas…
- sciascopy (fluoroscopy) : swallowing problems , with barium/iodine contrast
o Introduction:
Following are available for investigation:
1. Conventional/digital double contrast
2. CT
3 US
4. MRT (magnetic resonance tomography)
5. Angiography
6. PET-CT, PET-MRI
- multislice CT and high-field MRI are of crucial importance
- new methods like virtual colonoscopy are of gaining significance
o Transabdominal ultrasound:
- Free abdominal fluid (ascites, blood)
- Appendicitis
- Abscesses
- Diverticulitis
- Motility disorders
- Transrectal US is a standard procedure for diseases of rectum
o PET-CT and PET-MRI:
- Morphological changes in various diseases
- Metabolic changes in various diseases
- Especially useful for oncological imaging
o CTA/MRA:
- Diagnostic angiographu may be replaced by CTA/MRA
o Double contrast investigation:
- Is necessary for diagnosis of organ function, evaluation of the tightness of anastomoses and other postoperative questions
- Single contrast is primarily used for cases of suspected aspiration, perforation, postoperative dehiscence of anastomosis, fistula filling , intestinal obstruction o X-ray investigations and endoscopy:
- Complement each other and are no competing procedures
- Specific portions of the bowel are difficult to access by endoscopy (lower duodenum, small bowel, right sided colon)
o X-ray:
- Useful for functional disorders (deglutition) and dynamic investigation of pelvic floor, defecograpgy
- Also: Hernia, diverticula, fistula, intra-extra mural processes
o Endoscopy:
- Cytological investigation
- Histological investigation
o CT:
- Permits detection of affected segments of inflammation
- Abscesses
- Fistula
- Stenosis
- imaging techniques of oesophageal diseases
- oesophageal tumors (CT, barium swallow))
- hiatal hernia (x-ray - retrocardiac opacity +air fluid level) /floroscopy barium swallow)
- achalasia (barium swallow - bird beak sign)
Standard indications:
- Dysphagia
- Aspiration
- Globus sensation
- Non-cardiac chest pain
- Golden standard: Video Fluoroscopic swallowing exam
- Manometry (motility), ph-Metry (reflux), Endoscopy (assess mucous + biopsy) o Esophageal tumors:
- Benign – leiomyoma, neurinoma (rare)
- Malignant – carcinoma – more common in the mid and lower portion
- CT method of choice for staging a local finding
- Radiological investigation – polypoid exulceration or invasive stenosing carcinomas o Hiatus hernia:
- Occur when there is herniation of abdominal contents through the esophageal hiatus of diaphragm into thoracic cavity
- Types: axial, paraesophageal, mixed, total
- Plain radiograph – retrocardiac opacity with air-fluid level
- Barium swallowing/ Iod CM
o Achalasia:
- Caused by absence of relaxation of the lower esophageal sphincter combined with a functional disorder of the tubular esophagus
- Imaging:
1. Barium swallow/iod CM (confirm esophagus dilation, but also assessing mucosal abnormaltities. Findings include:
- Bird beak sign
- Esophageal dilatation
- Incomplete LOS relaxation
- Pooling or stasis of barium in the esophagus
- Uncoordinated, non-propulsive, tertiary
- Precancerous condition!
o Reflux disease:
- May occur with or without inflammation of the lower esophagus
- Most common inflammatory disease of esophagus
- Usually combined with hiatus hernia
- Metaplasia (barretts)
- Imaging: barium swallow + Valsalva maneuver
o Diverticula:
- False diverticula causally associated with motility disorders and local parietal weakness - Zenker´s most common
- Posterior wall of pharynx
- Epiphrenic and mid portion much more rare
- imaging techniques of gastric and duodenal diseases
- endoscopy
- double contrast (fluoroscopy , barium sulfate)
- gastritis ( erosions of gastroduodenal mucosa, may be seen)
- gastric cancer ( water + gas)
Introduction:
- Double-contrast investigation still indicated, but only when endoscopy is not fesible - Performed with fluoroscopy using barium sulfate and effervescent powder CM - All portions of stomach and duodenum are viewed in various positions by DCI
o Gastritis:
- Is no radiological diagnosis, but erosion of gastroduodenal mucosa may be visualized by radiological procedures
- NSAIDS, alcohol, nicotine, medication, biliary reflux (C)
- Helicobacter pylori (B)
- Immune/pernicious anemia/vitamin B12 deficiency (A)
o Ulcer:
- Duodenal much more common than gastric
- Typical feature is the contrast medium depot (niche)
- Same etiology as gastritis
- Endoscopy and biopsy to rule out cancer (gastric ulcer)
- Complications: bleeding, penetration, perforation (sepsis risk), stenosis
o Gastric cancer:
- Japan highest incidence
- Early gastric carcinoma – diagnosed by endoscopy
- Advanced stage – the majority are alcero-polypoid
- Hydro MDCT is superior to endoscopy in cases of suspected scirrhus and staging Mesenchymal tumors:
- Leiomyoma – most common mesenchymal benign tumor
- Mesenchymal tumors larger than 5 cm are usually malignant
- GIST (gastrointestinal stromal tumor)
- hydro MDCT also for mesenchymal
o Gastric polyps:
- Hyperplastic (95%) and adenomatous polyps (<5 %)
- Hyperplastic: small (5-10mm), multiple, smooth, sessile, round, benign, degenerate
- Adenomatous: rare, 40% develop into carcinoma within 4 years, > 1cm, Solitary, precancer
- imaging techniques of small bowel diseases
- enteroclysis (CT, MRI enterclysis, replacing conventional enteroclysis)
- crohn´s disease : barium fluoroscopy( deep fissuring ulcers around swollen mucosa)/ MRI enteroclysis (post contrast enhancement)/ CT enterography(tick wall SI)
o Introduction:
- Conventional enteroclysis is used to investigate the morphology and motility of small bowel - CT enteroclysis and MR enteroclysis more sensitive in morphological findings - Endoscopic: Esophago/gastro/duodenoscopy
- Enteroscopy: Endoscopic investigation of small bowel (therapeutic and biopsie too) - Capsule endoscopy: Swallowing video capsule
o Enteroclysis: Indications: 1. Suspected crohn´s disease 2. Search for tumor 3. GI bleeding due to unknown cause 4. Malabsorption syndrome 5. Radiation eteritis 6. Recurrent bowel obstruction 7. Meckel´s diverticulum Comparison: - Enteroclysis (x-ray) = 60 min, worse morphology investigation than CT/MRI, more radiation, better function than MRI/CT
X-ray investigation:
- double contrast investigation of small bowel (synonym enteroclysis)
- Preparation: six hours of fasting
- CI for barium: suspected perforation and obstruction of large bowel
- Indication: see above!
o Tumors, polyps (polyposis):
- Most common malignant tumors of the small bowel: carcinoma, carcinoid, lymphoma - The most common polyposis syndrome:
1. Peutz-jegher syndrome (frequent initial symptoms are intussusception, pain, bleeding and anemia
o Meckel´s diverticulum:
- Result of failed remission of the omphalomesenteric duct
barium filled pouch
- Complications: bleeding and invagination
Small bowel diverticula:
1. Frequently finds genuine juxtapapillary diverticula in the duodenum
2. Complications: diverticulitis, hemorrhage, perforation, obstruction, malassimilation
o Crohn´s disease:
- Transmural inflammation (all layers of the wall)
- Discontinous disease
- Deep circumscribed and linear ulcer interspersed with an edematous mucosa - Cobblestone pattern
- Inicial discrete aphthae
- Terminal ileitis (synonym)
- Complications: abscesses, fistulas, stenosis
- imaging techniques of large bowel diseases
- virtual CT colonoscopy + endoscopy
- diverticulosis ( barium enema/CT of abdomen/CT colonography 3D)
o Introduction:
- Irrigoscopy is in the recent years replaced by CT colonography (virtual colonoscopy) - Endoscopy and CT colonography is the most important procedure to investigate entire colon
o Colorectal imaging:
- Irrigoscopy:
- Barium contrast enema administered through the inserted flexible intestinal tube - When the right flexure has been reached, 1 ampule of buscopan is applied i.v - Insufflation of air
- At least 2 projections of each portion of the colon
- This method is replaced by CT colonography (virtual colonoscopy) - CT colonography:
- Indications: postoperative controls, preoperative investigation of carcinoma
o Diverticulosis:
- outpouching of bowel mucosa
- Most common disease of the large bowel (elderly)
- Symptoms: pain in the left-sided lower abdomen, fever, leukocytosis
- The majority in the left-sided colon (sigmoid)
- Complications: hemorrhage (mild), inflammation, abcess and fistula formation (with bladder/vagina)
o Colonic polyps:
- Circumscribed broad-based or pedicles lesions of the bowel wall
- Benign adenomatous polyps may develop into malignant adenocarcinoma - The most important radio criteria to assess malignancy: size (>2cm 50% risk of degeneration)
o Colorectal cancer:
- Most common carcinoma of the GI tract
- Most frequently located in the rectosigmoid portion
- Risk factors: history of adenoma/carcinoma, positive family history, ulcerative colitis, familial polyposis
diagnosis : bowel wall thickening, luminal narrowing
- colonoscopy - screening
- Ct - staging
o Diseases of the rectum and the anus:
- Carcinoma
- Inflammatory disease (fistula, abscesses)
- Fecal incontinence
- Constipation
- Image procedures: Endorectal/anal US, MRI (CT), Defecography
- Defecography: dynamic visualization of rectal evacuation, performed on a fluoroscopy device after rectal application of barium sulfate suspension
- MRI: Used for staging tumors and detecting inflammatory changes
o Tumor of rectum and anal canal:
- Most common location of large bowel
- Endosonography has a high spatial resolution
- MRI offers a better overview of the extent and position of tumor
- Anal carcinoma: transanal US for primary staging
- imaging techniques of diffuse liver diseases
o Introduction:
- Non-invasive imaging methods: USG, MR/CT + CM and PET CT
Interventional procedures:
- US/CT/MR-guided diagnostic puncture of liver lesions
- Image-guided percutaneous tissue destruction of malignant tumors such as radio frequency ablation or ethanol installation
- Angiographic interventional embolization of malignant processes (HCC, MTS) o Ultrasonography of liver:
- Routinely examined during the investigation of upper abdomen
- Primary imaging procedure
- Examination includes imaging of the gallbladder, bile duct and blood supply too - Normal hepatic parenchyma is more hyperechoic than renal parenchyma
o CT:
- Almost always performed with CM
Phases of enhancement:
1. Non-enhanced CT(NECT): Detection of calcifications, fat in tumors
2. Early arterial phase: Contrast still in arteries, not enhancing organs
3. Late arterial phase: All structures getting blood supply from arteries = enhanced 4. Hepatic phase: Liver parenchyma enhances
5. Delayed phase: Washing out contrast except in fibrotic tissue (poor late washout) o Fatty liver:
- Most frequently caused by obesity and alcohol
- Leads to hepatomegaly
- Diagnosis:
1. US: diffuse increased echogenity compared to kidney parenchyma
2. MDCT: reduction of density
o Cirrhosis:
- Diffuse process marked by advancing fibrosis and nodular remodeling of normal hepatic architetcture
- Causes: Hep B and C, alcohol
- Precancerous – imaging provide evidence of hepatocellular carcinoma at very early stage Diagnosis:
1. US: surface nodularity, heterogenous echotexture, segmental hypertrophy/atrophy, portal hypertension sign, acites, splenomegaly
2. MDCT: + heterogenous appearance of the liver parenchyma, regenerative nodules may be isodense or hyperdense
3. MRI: major role in identifying HCC ( contrast enhances)
- imaging of benign focal liver lesions
- hemangioma (most common benign liver tumor)
- hamartoma :(noncancerous tumor made of an abnormal mixture of normal cells from the area in which it grows)
Hemangioma:
- Most common benign liver tumor
- 4 types of them – cavernous hemangioma is the most common
Imaging:
1. US: hyperechoic and round (CAUTION! – in patients with oncological diease – hyperechoic MTS of the renal-cell carcinoma, breast CA, etc may look similar)
2. MDCT: typical nodular CM absorption starting from the margin and continuous slowly to mid-portion, homogenous staining in the portal venous phase
3. MRI (contrast enhanced): in case of uncharacteristic contrast behavior and strong clinical suspicion
- T1 ( post contrast enhancement )
- T2 ( hyperintense ) central scar
CM best identified in arterial phase = rich vascularization
o Focal nodular hyperplasia (FNH):
- hamartous benign tumor
- Well delineated
- Without capsule
- 2nd most common benign tumor of liver
- Women in reproductive age
Imaging:
- US: usually hypoechoic/isoechoic lesion, central vessel, spoke-like pattern of vascularization - MDCT: hypodense/isodense with a central scar
- MRI: T1W hypointense/isotense, central scar hyperintense on T2W
- Best visualized in arterial phase because of rich vascularization
o Hepatocellular adenoma:
- Normal but large hepatic cells with tendence to degenerate
- Associated with oral contraceptive use
- Single form, if number of lesion exceed 10 = adenomatosis
- Various in size – by larger lesion higher risk of hemorrhage
Image:
- Fatty portions and calcifications seen well on USG and CT
- Inhomogenous on non-contrasted images
- Non-contrast CT may show inward bleeding (hyperdense areas)
- Areas of inward bleeding
- CM application – hypervascularisation, enhanced is centripetal
- imaging of malignant focal liver lesions
- contrast MRI : most sensitive method for exact detection of HCC
o Hepatocellular carcinoma:
- Most common primary malignant hepatic tumor
- Risk factors: Hepatitis B and C, alcohol-induced cirrhosis
Imaging:
1. CM application MRI and CT: early arterial enhancement (hypervascularisation), followed by early washout
2. US: screening method for patients with cirrhosis (small HCC – hypoechoic, large HCC mixed echogenity)
3. MDCT: always performed as a multiphasic investigation
4. Contrast MRI is the most sensitive method for exact detection and characterization of HCC nodules
o Fibrolamellar carcinoma:
- Occurs in young patients
- Women
- Better prognosis than HCC
Imaging:
1. MRI: method of choice for differentiation from FNH – FNH shows contrast absorption, FLC demonstrates wash-out
o Liver metastasis:
- 90 % of malignant hepatic tumors are metastases
- From lung, breast, colon, rectum, stomach, pancreas, etc.
- Solid (hyper/hypovascular), cystic
Imaging:
1. US: hypoechoic/hyperechoic, have a hypoechoic margin (halo)
2. CT/MRI – higher sensitivity than Ultrasound
- imaging techniques of gallbladder and bile duct diseases
- MRCP : magnetic resonance cholangiopancreaticography - fluid is white
- ERCP : endoscopic retrograde cholangiopancreaticography
- PTC : percutaneous transhepatic cholangiography
gallstones - US hyperschoic + post acoustic shadow
bile filled bladder : US - anchoic + post acoustic enhancement
o Introduction:
- Affections of gallbladder and biliary tract are most common causes of symptoms in the right-sided upper abdomen
- Imaging procedures: US, MR, MRCP, CT (non-invasive), ERCP, PTC, EUS (invasive) o Ultrasound:
- First image procedure
- Thickness of the wall: 3-4 mm
- Diameter of biliary duct: up to 6 mm
o MRCP (specific T2W without CM):
- Complete images of intra- and extrahepatic bile ducts w/ surrounding structures - Comparable results to ERCP
o CT:
- No routine investigation
- For rare condtion of radiopaque gallstones, inflammatory complications, tumor staging o ERCP:
- Diagnostic and interventional
- Uses endoscopy and fluoroscopy for examination and intervention of biliary tree and pancreatic ducts
- Complications: pancreatitis, hemorrhage, pneumoperitoneum, infection o PTC:
- Performed when other less invasive methods of imaging the biliary tree have proven unsatisfactory
- Performed by passing needle thorugh hepatic parenchyma into lumen of bilde duct - CM injected and biliary tree imaged (biliary obstruction, interventional procedure) o Gallstones:
- Numbers and various sizes
- US: method of choice
- Gallstone: hyperechoic structure with convex surface
o Gladdbladder sludge:
- Exceptionally thick bilde due to oversaturation with cholesterol
- US: hyperechoic material
o Bilde duct stones:
- Mainly extrahepatic location
- Complications: hydrops, acute cholecystitis, chronic cholecystitis
Imaging:
1. ERCP: invasive, but extraction of stones is advantage
2. US: but the sensitivity is lower than gallbladder
3. MRCP: sensitive, replace diagnostic ERCP
o Biliodigestive fistulas:
- Large solitary gallstones may lead to biliodigestive fistula
- Causes this by chronic inflammation and penetration of surrounding tissues - Typical sign: pneumobilia
o Cholangitis:
- Caused by biliary obstruction
- Impaired drainage with secondary hematogenic bacterial infection
- Sometimes ascending infection from bowel
- Causes: bileduct stone, tumor/inflammatory compression, postoperative
- Complication: abscess and chronic cholangitis
- Specific types: 1. PSC – diffuse fibrosis and multiple stenosis (ERCP, MRCP), 2. AIDS associated cholangitis
Imaging:
1. Dilatation of intra- and extrahepatic bilde ducts
2. Filled with putrid secretion
3. Thickened wall of bile duct
4. PTC or CT
o Neoplasis of gallbladder:
1. Cholesterol polyps:
- US immovable hyperechoic parietal structures
2. Gallbladder carcinoma:
- Rare malignant tumor, diagnosed in advanced stage
- Diffuse or polypoid thickened wall with constriction of lumen (containing gallstones) 3. Cholangiocellular carcinoma:
- Most common is the klatskin´s tumor in the hepatic fork
- Imaging: MRCP
- imaging techniques of pancreas diseases
o Introduction:
1. Imaging for diagnosis:
- USG: transabdominal, endoscopic, intraoperative
2. Contrast-enhanced CT
3. MRI
4. MRCP/ERCP
o Acute pancreatitis:
- Bile duct stones, alcohol
- Diagnosis: 2 of 3 (typical abdominal pain, serum lipase or amylase activity increased, characteristic CT findings)
- Ultrasound: hypoechoic, thick due to edema, fluid collection
- MDCT: method of choice (for prediction of clinical outcome recommended on 2nd-3rd day after admission)
- Presentation: thickened pancreas, extrapancreatic exudate, parenchymatous/fatty necrosis, spread of inflammation through pathways
- Complication: bacterial infection, abscess, pseudocyst, hemorrhage, pleural effusion - CTSI: 0-2 mild, 4-6 moderate, 8-10 severe (based on inflammation and necrosis)
o Chronic pancreatitis:
- Fibrosis
- Alcohol
Complications:
1. Biliary complications: compression of common bile duct 🡪 cholestasis
2. Vascular complications: Erosion of peripancreatic arteries (hemorrhage, pseudoaneurysm), thrombosis of splenic veins
3. GI complications: stenosis of pyloric orifice/duodenum due to pseudocysts 4. Pseudocysts (more common than after acute pancreatitis)
Imaging:
1. MRCP:
- Method of choice
- Signs: dilatation of pancreatic duct (irregular), strictures, pseudocysts
2. US:
- Used as follow up of monitoring pseudocysts
3. ERCP:
- Therapeutic interventions (drain of a pseudocyst, stone extraction, stenting of stricture) o Adenocarcinoma:
- Most malignant tumor of pancreas
- 3rd most common malignant tumor of GIT
- Symptoms: weight loss, icterus
- Bad prognosis, operable only 20 % (whipple´s operation)
- Findings: circumscribed/diffuse enlargement of organ
Imaging:
1. US: hypoechoic space-occupying lesion blurred margins
2. MDCT + contrast: hypodense lesion with lesser absorption of CM
- Method of choice (MDCT) for postoperative follow up!
3. MRCP/ERCP: dilated bilde duct and pancreatic duct in tumors of the head o NET´s:
- Arise from stem cells along pancreatic ducts
- Benign, borderline, highly differentiated, undifferentiated carcinoma
- 1/3 hormone producing (insulin, glucagon, gastrin, VIP)
- Most common is insulin (benign in 90 %)
Diagnosis:
- lab tests + imaging
1. MRI or endo US
2. PET-CT with special tracers can depict extrapanreatic tumors or metastasis o Cystic tumors:
- Pseudocyst most common
- Serous cystadenoma (small cysts)
- Mucinous cystadenoma/cystadenocarcinoma (large cysts)
- MRI method of choice! / endo US for biopsy
- imaging techniques of splenic diseases
Introduction:
- Diagnostic imaging includes US (homogenous echo structure), MDCT/MRI - Homogenous echo structure on ultrasound
- Hypodense in non-contrasted CT scan
- Primary diseases are rare, but organ is frequently involved in other diseases - Spleen is routinely visualized during US investigation of upper abdomen - In cases of ambiguous changes, CT is method of choice
- US and CT are methods of choice in emergency room
o Splenomegaly:
- Most common alteration
- Caused by sepsis, neoplasm, hematological, portal hypertension
- Enlargement of the spleen
o Benign tumors:
- Rare
o Malignant tumors:
- More common
- Lymphomas (hypodense on contrast CT)
- Metastases (rare) (hypodense on contrast CT)
- Primary sarcoma (hemangiosarcoma)
o Other:
- Abscesses
- Infaction
- Cysts
- None of them are very common
o Primary cyst:
- Parasitic (echinococcus), non parasitic (congenital, neoplastic)
o Secondary cysts:
- Infarction, trauma (most commonly organ injured after blunt abdominal trauma)
