imaging abdominal viscera

Question 1

imaging modalities for the abdomen

Answer 1

Xray/fluroscopy
US
CT
MRI

Question 2

what are the two types of imaging views

Answer 2

plain (superimposed front to back) and cross sectional (slices)
planes - axial cronal and sagittal

Question 3

what are the differences in resolutions

Answer 3

spatial and contrast resolution

Question 4

what are the images of MRI

Answer 4

Many types of image sequences, weighted T1 - fluid is black and T2- white

Question 5

what is contrast

Answer 5

used to increase contrast resolution (eg highlight specific areas/organs)
given via IV or enteral (oral/PR) before scan
either more or less dense than surrounding tissues (XR/CT) or paramagnetic (MRI)

Question 6

pros of xray

Answer 6

cheap 
quick
easy for pt
high spatial resolution 
low radiation dose

Question 7

cons of xray

Answer 7

poor contrast resolution

planar imaging

Question 8

pros of CT

Answer 8

quick
widely available
cross sectional images
high contrast resolution

Question 9

cons of CT

Answer 9

radiation dose

IV contrast risks

Question 10

pros of US

Answer 10

cheap
quick
no radiation 
cross sectional images 
US guided interventions

Question 11

cons of US

Answer 11

saved images are only a snapshot of exam (operation dependant)

Question 12

pros of MRI

Answer 12

contrast resolution
specific applications
no radiation

Question 13

cons of MRI

Answer 13

limited availability
patient experience (time, space)
expense
magent/contrast risks

Question 14

how does the structure of an organ affect imaging

Answer 14

solid (eg kidney) vs hollow (eg bladder) viscera

modalities look at different ones better, eg US can’t go through air in hollow viscera

Question 15

how does positioning affect imaging

Answer 15

intra vs retroperitoneal (inside peritoneal layer, single layer or double surrounding)
determines how pathology spreads through abdomen

Question 16

how does circulation affect imaging

Answer 16

systemic vs portal circulation

Question 17

what are the solid abdominal viscera

Answer 17

liver spleen pancreas

Question 18

what is the liver structure (basic)

Answer 18

RHV, LHV and MHV entering top to drain
CBD, HA and PV entering bottom, triad goes to 8 segments (divided by portal vein horizontally and hepatic veins vertically)
biliary system

Question 19

how is the liver imaged via US

Answer 19

hepatic and portal veins 
 IVC 
 fluid movement via doppler flow
can see GB (useful for gallstones, shadowing white structure)
metastasis (dark blobs)

Question 20

How is the liver imaged by CT

Answer 20

Hepatic veins (R, M, L) IVC, portal vein from celiac artery (axial)
downwards can see stomach via air and other organs 
can do contrast eg to see vessels
gallstones, dilated bile ducts and metastasis

Question 21

how else can the liver be imaged

Answer 21

intervention radiologists (real time imaging to diagnose and sort issues eg blocked vessels)
ERCP (endoscope with camera, also using xray to guide)
PTC (see bile system)
DSA (see arteries via catheter)
MRI (detail of biliary system)

Question 22

what is basic structure of the spleen

Answer 22

LUQ at tail of pancreas

splenic vein

Question 23

how is the spleen viewed

Answer 23

coronal above kidney

axial stomach and liver anterior

Question 24

imaging pathologies of spleen

Answer 24

spleen can be shattered by trauma and replaced by haematoma
lymphoma
lesions
CT

Question 25

basic structure of the pancreas

Answer 25

head of pancreas in curve of duodenum to boy and fungus lobules pancreatic duct to join CBD into duodenum

Question 26

how is the pancreas seen on US

Answer 26

courses round splenic vein

Question 27

how is the pancreas seen on CT

Answer 27

crisp outline with sup mes vein and artery

Question 28

how is pathology seen

Answer 28

loss of outline, enlarged, irregular and areas of lower density - acute inflammation (pancreatitis)

Question 29

hollow viscera of the abdomen

Answer 29

stomach, SB, LB | Xray good first line rest then MRI and CT (avoids endoscopy)

Question 30

imaging the bowel by xray

Answer 30

``` normal calibre (LB 5cm and SB 3cm) looking for free air, normal distribution of bowel gas ```

Question 31

how is the stomach seen on xray

Answer 31

LUQ, fundus under left hemidiaphragm, obliquely orientated contains fluid and air wall is regal folds size variable

Question 32

how is the SB seen on xray

Answer 32

``` central abdomen fluid and air contents encircling valvular conniventes- wider in ileum spaced out when distended <3cm diameter ```

Question 33

how is the LB seen on xray

Answer 33

``` peripheral, LB frames SB faeces (liquid and hard) haustral folds spaced out when distended <6cm, <9cm caecum ```

Question 34

how can a chest xray be used

Answer 34

perforation (free gas in highest point, diaphragm)

Question 35

how is the bowel screened

Answer 35

fluoroscopy single contrast barium follows through works with gas for double contrast (barium enema, hard for frail and elderly)

Question 36

bowel imaging via CT scan

Answer 36

CT colonography | look for polyps or 3D fly through to prompt colonoscopy

Question 37

bowel imaging via MRI

Answer 37

Seen detail in bowel | IBD in SB and rectal tumour staging in LB