Abdomen And Pelvis Radiology
Wala Issa Bani hamad M.D JBR
• https://www.radiologycafe.com/medical-students
What Will be Discussed
G.I Tract
GU Tract.
Anatomy.
Radiological Overview.
Radiograph.
C.T Scan.
Flouroscopy.
Ultrasound,, Liver and Right Kidney
INFERIOR
Abdominal Aorta Non Paired Branches
Aortic branches
Celiac artery
• A.K.A celiac axis or celiac trunk.
• supplying the foregut.
• It arises from the AA and commonly gives rise to three branches:
• Left gastric artery.
• Splenic artery and
• Common hepatic artery.
• AA: abdominal aorta
Celiac trunk
pancreas
Rt adrenal
Lt adrenal T12/L1
Celiac Trunk Seagull sign :
Bifurcation into common hepatic
and splenic arteries
Gall bladder
Superior mesntric artery
L1
• Arises at L1 level • Below SEAGULL SIGN • At the confluence
of portal vein
Diffuse small-bowel ischemia in 60-year-old man with occlusive mesenteric ischemia. Axial CT scan obtained at level of inferior mesenteric artery (arrow) shows large caliber of this vessel. Long segment of small-bowel dilatation has minimal wall thickness of 1-2 mm.
Lt renal artery
Lt renal vein
L1/L2 L3
IMA
IMA: Arises at L3 below SMA Going to left with all its branches.
Inferior Mesenteric Artery
Small Bowel
Second Part of Duodenum
passes between
pancreas and liver
Third part
passes anterior to the Aorta
Jejunum seen at left upper
quadrant
Ileum seen at right lower
quadrant
Radiograph
It is worth knowing that only five basic densities are normally present on X-rays, which appear thus:
Gas - black
Fat - dark grey
Soft tissue/fluid - light grey
Bone/calcification - white
Metal – intense white
N.B: Always check left and right on every film, consciously and routinely –especially just before surgical operations.
Indications (acute)
Emergent evaluation of bowel gas
negative study in some patients may obviate the need for CT
Evaluation of :
radiopaque lines and tubes
radiopaque foreign bodies
postprocedural free gas
bowel gas in postoperative ileus
benefits
• quick and accessible
Limitations
MODEST RADIATION DOSE LOW SENSITIVITY AND SPECIFICITY FOR INTRA-
ABDOMINAL PATHOLOGY
PREGNANCY IS A RELATIVE CONTRAINDICATION
procedure
patient is supine
radiograph is performed AP (anteroposterior)
performed in the radiology department
mobile abdominal radiographs are poor quality
only performed mobile if the patient is very ill
No evidence of pneumoperitoneum.
The bowel gas pattern is normal. No
evidence of bowel wall thickening. Small
right pelvic phlebolith. The
bones are normal. The lung bases are
clear.
No evidence of pneumoperitoneum.
The bowel gas pattern is normal. No
evidence of bowel wall thickening. Small
right pelvic phlebolith. The
bones are normal. The lung bases are
clear.
Purple:Liver Pink: Spleen
Green: Left 11th Rib Orange: Kidneys
Red: Psoas muscle Brown: Spinous process of L1
Light Blue: Pedicles of L3 Black: Transverse processes of L3
Yellow: Vertebral body of L4 Dark Blue: Urinary bladder
Dotted Green: Usual path of the ureter (not usually visible)
Dotted White: Left sacroiliac joint
Pathology
Pathological findings on plain
films
GAS
• Intra-luminal
• Extraluminal
• Intra-peritoneal
• In portal
• In biliary tree
CALCIFICATION
•Phleboliths
•Vascular calcifications
•Calcified LNs
•GBS
•RS / UBS
•Splenic / hepatic granulomas
•Appendicoliths / enteroliths
•Calcified adrenals
AIR
air should only be within bowel loops
free peritoneal air is known as pneumoperitoneum
erect chest x-rays are more sensitive to the presence of pneumoperitoneum than abdominal x-rays
however, there are some key signs on abdominal x-rays of a pneumoperitoneum
Pneumoperitoneum
The Rigler sign, also known as the double wall sign,seen when the air is present on both sides of the intestine, i.e. when there is air on both the luminal and peritoneal side of the bowel wall.
Pneumoperitoneum may be a result of perforation or, recent instrumentation or surgery.
Pneumoperitoneum
look at the wall of the bowel - is it seen as a crisply defined thin white line (Rigler's sign)?
can you see small triangles of air between bowel loops?
can you see the falciform ligament outlined by gas on either side?
does the liver look more lucent than expected?
Gas in the right upper quadrant within the biliary tree is a “normal” finding after sphincterotomy or biliary surgery, but it can indicate the presence of a fistula between the biliary tree and the gut.
Beware of gas in the portal vein, as this can look very similar to biliary air. Gas in the portal vein is always pathological and frequently fatal. It occurs in ischemic states, such as toxic mega colon, and it may be accompanied by gas within the bowel wall (intramural gas).
Portal Venous Gas; Contrast CT image reveals gas in the portal vein, seen as air-density tubular structures extending to the periphery of the liver. Gas in the biliary tree(Pneumobilia) is central and does not extend into the peripheral 2 cm of the liver. In this case, portal venous gas was associated with infarction of the small bowel.
Bowel
stomach, small bowel and large bowel may be differentiated on an abdominal x-ray
pathological features to detect include bowel dilatation, bowel loop displacement and bowel wall thickening
procedure
• the small bowel usually lies centrally, has folds than run all the way across the diameter of the lumen (valvulae conniventis) and usually contains a small volume of air.
• the Large bowel lies peripherally, has folds that run part of the way across the diameter of the lumen (haustral folds) and usually contains some air and fecal matter
Is the bowel dilated?
The 3-6-9- rule refers to the approximate allowable diameter (in centimeters) of the small bowel, large bowel and cecum
3: Small bowel .
6: Colon.
9: Cecum.
Differentiation between bowel on radiograph
Small bowel dilatation
Air fluid level
Distended loops of small bowel and sigmoid colon,
measuring up to 6cm.
Free intraperitoneal gas, with visibility of the inner and outer walls of the bowel
(Rigler's sign).
Large bowel dilatation
Diameter more than 6 cm
Densities
several bony structures are visible on an abdominal x-ray and should be evaluated carefully
calcification may also be visible and may provide a clue as to the cause of the patient's symptoms and signs
Bone And Calcifications
evaluate all of the bones visible on the x-ray as you would on any other x-ray
look at the contours, density, trabecular pattern, areas of lysis or sclerosis
you may see the lower thoracic vertebral bodies, all of the lumbar vertebral bodies, sacrum, iliac blades, ischium, femoral heads and necks, and lowest ribs
examine the renal shadows and paths of the ureters for small densities which indicate stones.
Gall stones are radioopaque in approximately 15-20% of cases
Bone And Calcifications
other calcifications include:
Uterine fibroids calcified
mesenteric lymph nodes
Hepatic/splenic granuloma
Injection sites
calcified lymph nodes are also sometimes identified
small pelvic calcifications are likely to be phleboliths
calcified adrenal glands
% of radio-opaque gallstones? % of radio-opaque urinary stones?
15% %85
pelvic vein phleboliths (calcified thrombi) mostly 5mm or less with central lucent
C.T
• It obtains a series of different angular x-ray projections that are processed by a computer to give a section of specified thickness.
Systematic Approach
• - Mention the section , body area
• - Contrasted versus non contrasted
• - The side for any paired organ
• Click to add text
Absolute positive: BONE +1000 Contrast: 150 Soft tissue: 40-60 Neutral: FLUID 0 Fat: -20-30 Absolute negative: GAS - 1000
Contrasted V.S Non
contrasted
Indications
Abdominal Pain
abdominal sepsis
Bowel obstruction
post-operative complications
trauma
vascular compromise, e.g. Aortic aneurysm.
Benefits
relatively quick and accessible
reproducible findings
complete assessment of the abdomen and pelvis
limitations
Uses Ionizing Radiation
risk of radiation-induced cancer
approximately 100 times the dose of a chest radiograph
requires iodinated I.V Contrast
risk of deterioration in renal function
risk of anaphylactic reaction
procedure
check renal function
lie patient supine on CT table
scout image to plan study
IV contrast injected via pump-injector
60-second delay
scan from dome of diaphragms to symphysis pubis
variations on a theme
• differing the IV contrast injection and timing may be useful
• dual-phase CT abdomen
• two scans (one arterial and one portovenous)
• assessment of vascular supply and parenchyma
• CT pancreas
• 3-phase non-contrast, arterial and portovenous
Pathology
Gastrointestinal Tract
Small Bowel Obstruction
Causes :
Adhesions.
herniae .
and gallstone ileus.
The ‘transition point’ is the point at which proximal bowel is dilated, and distal bowel is collapsed. This usually indicates site of obstruction.
Mechanical vs Functional Obstruction
• Small bowel ileus occurs due to metabolic derangements or post-operatively, with dilatation but no transition point.
Appearance: Dilated small bowel loops proximal to a transition point; Multiple air-fluid levels; Possible ischaemic bowel , at this image inguinal hernia is noted
Large Bowel Obstruction
causes : Cancers.
Diverticulosis Volvulus.
Competent ileocecal valve?
An obstruction of the large bowel causes dilatation of proximal large bowel.
However, the small bowel may or may not be dilated
This depends on ileocaecal valve competency.
.It is competent in ~70% of people.
A competent valve traps contents in the large bowel, so the small bowel is not dilated.
this causes the large bowel to dilate much more and much quicker, putting it at a higher risk of perforation.
The 3-6-9 rule:
Dilated Small bowel: > 3 cm
Dilated Large bowel: > 6 cm
Dilated Caecum: > 9 cm
Appearance: Dilated large bowel
loops proximal to a transition point; M
ultiple air-fluid levels; Dilated
small bowel loops if
valve incompetent
Gallstones
Ultrasound is the gold standard investigation.
CT may miss some stones.
Plain X-ray only shows 10% of stones.
MRCP is useful for ductal stones.
Locations: Gallbladder, Bile ducts, Small bowel (rare).
Appearance
• Ultrasound, single or multiple hyperechoic objects in the gallbladder, with acoustic shadowing.
• On CT, stones may be:
• hyperattenuating (calcified stones),
• isoattenuating (mixed),
• or hypoattenuating (cholesterol stones)
• On MRI, stones are an area of low signal (dark).
Ultrasound Semilunar echogenic intraluminal structure with posterior acoustic
shadowing suggestive of gallstone
C.T coronal images showed hyperdense gallstone
MRI multiple small hypoattenuating round structures suggestive of gallstones
Cholecystitis
Commonly due to gallstone disease.
Biliary colic: Right upper quadrant pain
Cholecystitis: Right upper quadrant pain + Fever
Ascending cholangitis: Right upper quadrant pain + Fever + Jaundice (Charcot’s triad)
Appearance
Distended fluid-filled gallbladder
Thick enhancing (bright) gallbladder wall
Fluid surrounding gallbladder
‘Fat stranding’ surrounding gallbladder (fluid density due to oedema in fat)
C.T Distended
gallbladder with wall thickening
and pericholecystic edema suggestive of cholecystitis
Ultrasound Distended gallbladder
with stone, wall thickening and pericholecystic
edema
Pancreatitis
• Complications include peripancreatic fluid collections (if encapsulated, these are called pseudocysts);
• abscesses;
• necrosis of pancreatic tissue;
• thrombosis of splenic/portal veins;
• and pseudoaneurysms +/- haemorrhage.
Appearance
Enlarged, oedematous pancreas
Fuzzy pancreas borders
Fluid around pancreas
‘Fat stranding’ in retroperitoneum (fluid density due to oedema in fat)
Areas of non-enhancement indicate necrosis
C.T coronal image showed heterogenous partially
non enhancing pancreatic parenchyma
with misty fat planes and surrounding fluid
suggestive of pancreatitis
Edematous, swollen
Renal Stones
99% of stones are visible on CT KUB (done without contrast).
CT shows the exact location of calcifications to see whether or not they are located within the renal tract.
Any associated obstructing effect causing hydroureter or hydronephrosis can be seen.
Inflammation around the ureter may also be seen which could indicate a recently passed stone.
‘Follow’ the ureter from where it leaves the renal pelvis, down along the psoas muscle, anterior to the sacroiliac joint, along the pelvic sidewall, until the ischial spine where it turns medially to reach the bladder.
Appearance
• Very small (2-10mm) hyperdense object within the renal calyces, renal pelvis, or within the course of the ureters. Possible associated hydronephrosis and hydroureter.
The path of the left ureter is
outlined with a yellow arrow. r
enal stone is indicated
with red arrow.
Bilateral nonobstructing
renal stones
Hydronephrosis
• Caused by a distal obstruction:
• stones,
• cancers,
• prostatic hypertrophy,
• pregnancy,
• congenital,
• large blood clot,
• retroperitoneal fibrosis;
• or backflow e.g. vesicoureteral reflux.
• The affected kidney frequently has impaired function. Further radiological tests to assess function include delayed phase contrast CT, intravenous pyelogram, or nuclear medicine tests.
Appearance: Enlarged renal calyces and renal
pelvis. Look for visible cause of
obstruction.
Appendicitis
Appendicitis can present at any age.
In children, mesenteric adenitis is a common and harmless differential that should be considered.
In older people, an underlying caecal carcinoma needs to be considered.
The diagnosis can be made on U/S although the appendix is frequently not visible due to being obscured by overlying bowel gas (65%).
Appearance
Dilated, fluid-filled appendix
‘Fat stranding’ around appendix
Possible associated soft tissue mass (lymphoid tissue, cancer); or hyperdense faecolith at base of appendix
U/S Appendicitis Blind ended non
compressible tube like
structure with wall thickening
and appendicolith
C.T ...Appendicitis the appendix is distended
with misty fat planes and congested mesentry
Diverticulitis
Typically occurs in those over 40
• Terminology
• Diverticulum: Single small outpouching of the bowel
• Diverticula: Plural of diverticulum (i.e. more than one diverticulum)
• Diverticulosis: Multiple diverticula, however no evidence of diverticulitis
• Diverticulitis: Inflammation or infection of a diverticulum
• Diverticular disease: When diverticula are associated with symptoms (e.g. abdominal pain)
Appearance
• Diverticula are multiple small outpouchings, particularly affecting the sigmoid colon. If these are inflamed (diverticulitis), there will be fat stranding, with possible localised perforation or collections.
C.T Divertriculosis multiple small outpouching
of sigmoid colon surface
Diverticulitis C.T
Ischaemic Bowel
Bowel ischaemia may be caused by:
arterial insufficiency (thrombosis or embolism),
venous obstruction,
or as a result of bowel obstruction.
Appearance: Variety of appearances including hypo- or hyper-density of the bowel wall, bowel distension and congestion of the mesentery. Arterial filling defect.
Bowel Ischemia with portal vein
thrombosis , thickened
bowel loops and
surrounding fatty stranding
Infarcted Bowel
Infarcted and gangrenous tissues will start to produce gas.
Therefore, severely infarcted or necrotic bowel may have gas within its walls.
The portal venous system drains the bowel walls. As a result, the portal vein fills with gas that drains into the liver.
Appearance: Air within bowel walls; Air in hepatic portal venous system.
Pneumobilia vs portal venous gas
• The liver shows a widespread branching pattern of portal venous gas, which is a premorbid sign (this is different from pneumobilia, which looks similar but the air is actually within the intrahepatic biliary ducts, seen when there is a fistula between bowel and gallbladder)
C.T coronal images showed necrotic bowel wall in form of pneumatosis
intestinalis with portal venous
gas.
Gas in Peritoneum
Causes of gas/air within intra- or retroperitoneal spaces:
Perforation - of hollow viscus (usually duodenum or sigmoid)
Recent laparoscopic surgery - from CO2 insufflation
Appearance
Free air within the peritoneum. Location of the air depends on the segment of perforated bowel i.e. intra- or retro-peritoneal.
Air can extend into other spaces e.g. pneumomediastinum.
Perforation of the rectum - air in mesorectum (mesentery surrounding rectum).
C.T axial images showed free air in the abdomen
Abdominal Aortic Aneurysm
Focal dilatation of the abdominal aorta.
Two-thirds of patients with ruptured AAAs die before reaching hospital.
Of those who make it to emergency surgery, half die.
Ultrasound used for diagnosis and screening. CT used for suspected leak, but this must not delay emergency surgery.
AAA
Screening for AAA is offered to all men when they turn .
It is a quick ultrasound scan to measure the abdominal aorta, done in the community.
If the test is negative (< 3 cm), there will be no further recall scans, unlike other screening programmes.
If the test is positive (> 3 cm), further action depends on the diameter of the aneurysm:
3.0 - 4.4 cm = repeat in 1 year;
4.5 - 5.4 cm = repeat in 3 months;
> 5.5 cm = immediate referral to vascular surgeons to consider elective repair
Appearance Aneurysm wall usually calcified.
If ruptured, free blood (higher density than fluid e.g. in stomach/GB) with possible contrast leak.
Mural thrombus common, seen as circumferential low density area.
AAA C.T massive dilatation of the abdominal aorta with wall thickening
Caecal volvulus
• describes torsion of the cecum around its mesentry which often results in obstruction . If unrecognised, it can result and fecal peritonitis..
Massive caecal volvulus.
Dilated caecal bowel loop reaching the left
upper quadrant
Plain radiograph...Caecal
Volvulus
• On abdominal radiographs, there is marked distension of a loop of large bowel with its long axis extending from the right lower quadrant to the epigastrium or left upper quadrant.
Markedly dilated loop of colon with a coffee-bean shape. Its apex points toward the right upper quadrant. Lucency at the right edge of the dilated bowel most likely represent compressed ascending colon.
• Grossly-dilated loop of large bowel has a 'coffee-bean shape' and the descending colon tapers in its inferior portion in keeping with a sigmoid volvulus. Air-fluid levels on erect projection.
Whirlpool appearance of midgut volvulus.
• The whirlpool sign of the mesentery, also known as the whirl sign, is seen when the bowel rotates around its mesentery leading to whirls of the mesenteric vessels.
Gynaecology
The preferred modality for initial diagnosis of a suspected gynaecological pathology is ultrasound (transabdominal or transvaginal).
Uterine fibroids can be very large and cause pain if they degenerate. Endometriosis may present as ovarian masses, partially cystic, or as deposits anywhere within the abdominal cavity.
Gynaecologic malignancies are staged with MRI & CT. Ovarian cancer tends to present late, frequently with spread to the peritoneum and omentum by diagnosis.
A ‘Krukenberg tumour’ refers to a metastatic deposit in the ovary which originated from a primary elsewhere within the peritoneal cavity.
Appearance: Uterine fibroids can calcify
and are seen as rounded masses with calcific rims.
Ascites
Ascites is seen in chronic liver disease, heart failure and abdominopelvic malignancies. It presents as abdominal distension.
It can be seen easily on ultrasound and CT. Ultrasound guided paracentesis/drainage can be carried out. A sample of ascitic fluid can be obtained for laboratory testing.
Appearance: Depending on the quantity, it is usually seen as fluid around the liver and spleen, surrounding the bowel, and in the pelvic cavity. It travels to dependent locations, i.e. the left and right paracolic gutters (folds of peritoneum) posteriorly.
U/S .. Ascites moderate amount of anechoic free fluid surrounding liver and bowel
C.T ...Ascites Low density free fluid surrounding the abdominal organs
FlOUROSCOPY
• The bowel filled only with barium, no air introduced.
• the mucosa is coated with barium and the stomach or colon distended by introducing gas, often combination with short acting smooth muscle relaxant.
• Double contrast shows more mucosal detail
Filling defect
- intraluminal filling defect
- intramural filling defect
-extramural compression
Ulceration
-Benign
-malignant
Stricture
-Benign
-malignant
ACHALASIA
• Primary achalasia: Primary motility disorder of the esophagus smooth muscle)
• Secondary or pseudoachalasia: Involvement of gastroesophageal junction by other abnormalities (Chagas disease, tumor)
• Diffuse mediastinal widening with air-fluid level suggests achalasia
•
Radiographic Findings
Mediastinal widening (double contour.)
Marked dilated esophagus
Retro-tracheal air-fluid level
"Bird-beak" deformity of distal esophagus
Little or absent gastric air bubble
Achalasia
Acute tapering at the lower esophageal
sphincter and narrowing at the
gastro-esophageal junction, producing
a "Bird beak" or "rat's tail" appearance.
PA chest radiograph demonstrating a relatively small gas–fluid level in the
mediastinum in a patient with achalasia. Note the soft-tissue density mass
representing the distended oesophagus inferior to the fluid level
Bird-beak" deformity
Is a herniation of the stomach into the mediastinum through the oesophageal hiatus in the diaphragm.
2 general types
- Sliding (axial) hiatal hernia, most common*
• Gastroesophageal (GE) junction and gastric cardia pass through esophageal hiatus of diaphragm into thorax
- Paraesophageal (rolling) hernia rare*
• Gastric fundus ± other parts of stomach herniate into chest while GEJ in normal position.
On conventional xray
Mass with air fluid level at rettrocardiac space
Sliding (axial) hiatal hernia
On barium studies
Sliding hiatal hernia
Paraesophageal hernia
Barium study shows a barium outlined stomach which has herniated into the thoracic cavity along with the gastro-esophageal junction which is evident on AP and oblique views.
Mediastinum enlarged with a para-cardiac
lucency indicative of air. The findings are in
keeping with a hiatus (paraesophageal) hernia.
The stomach and duodenum
Barium meal is the standard contrast medium to examine the stomach and duodenum.
Patient drinks about 200 ml of barium.
Better mucosal detail, the stomach is distended by giving a gas producing agent .
Intravenous injection of a short acting smooth muscle relaxant
Fasting patient for at least 6 hours.
Normal barium meal
Colon Carcinoma
Malignant transformation of colonic mucosa
Imaging
Location: Cecum (10%), ascending colon (15%), transverse colon (15%), descending colon (5%), sigmoid colon (25%), rectosigmoid colon (10%), rectum (20%)
Radiology is critical for screening, diagnosis, treatment, and follow-up of colorectal carcinoma
Detection: Double contrast barium enema
Early cancer: Sessile (plaque-like) lesion or thick, short polyp
Advanced cancer: Large polyp, "saddle" or "apple core" lesion