L17 Investig GI Sys

Question 1

LO2: recog keys strucs in X sec images of abdo.

Answer 1

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Question 2

LO3: list comm reasons for req plain abdo radiograph.

Answer 2

-Why req AXR- acute abdo pain? If not see append or gyn pain. Small or LI obstruc. Acute exacerb IBD partic toxic megacolon. Renal colic?? Now low dose CT first tell if stone or hydronephrosis. NOT constip, only v occas in kids.

Question 3

LO4: comp and contrast app of SI and LI on abdo radiograph and desc classic images of bowel obstruc.

Answer 3

• AXR SI cent, often don’t see. valvulae conniventes cross ent wall, thin.
• AXR LI periph. Haustra not full X bowel wall. Faeces and gas, low transit time. T colon hang down to pelvis, fem longer so colonosc more fail. S colon can loop and be long, can move, trace from caecum.

Question 4

LO5: expl role of erect chest radiograph in ass of acute abdo pain.

Answer 4

–CXR for perforation- pneumoperitoneum. Gas up to under diaph. Need able sit 10-20min.
Peptic ulcer, divert, tum, obstruc, trauma, iatrogenic eg laparoscopy.
Subtle signs on AXR. CT after CXR us.

Question 5

LO6: recog use of CT and MRI in investig abdo and Id key anat strucs.

Answer 5

ABDO CT: comp axial tomog.
-high dose rad but use lot esp acute. Good spat resol, poor contrast resol vs MRI. Use IV or oral/rectal contrast not much now.
-abdo CT spinal levels and planes. Transverse. Sagittal. Coronal. Look up form bott so opp. L1 trans pyloric plane of Addison. CT reformatting of visc struc.
-virtual colonosc- repl barium enema. Gastrograph White liv drink paint stool. Gas in bum. Diff planes. Fly through- tol, less perfor. See eg polyp.
-thick bowel, mesenteric, retro perit strucs and aorta. Detec perfor viscus, subdiaph abcess, extra luminal in append and diverticulitis. Contrast extravasated from int lumen and free air detected.
ABDO MRI: mag reson
-no rad. Good spat and contrast resol. Time consuming and req still. Better soft tiss defin. SI diffic as move= fuzzy.
-MR cholangio pancreatogram (MRCP) of bill tree. See gallst.
-SI MR- fill fluid, look at wall eg crohns, no rad expos good for yng pt need rep imaging. Eg crohns structure, see peristalsis motil.
-MRI good for abcess, fistulae in peri anal reg. Comm in hepatobil and panc dis.

Question 6

LO7: disc basic interven radiologic proceed used in managem GI dis.

Answer 6

GI ANGIOGRAPHY:
-endo vasc treat of aneurism.
-demonstr GI vasc sys foll punc, Catheter, and infec of radio opaque contrast to BV.
-isotope studies- lim use now as CT and MRI. IV isotope dissip to tiss= faint backg on gamma cam. Active fast bleed prod pool bef isotope leaves blood=patch gamma activ.
GI STENTING:

Question 7

LO1: AXR soft tiss

Answer 7

-soft tiss eg organs- liv, spleen, kidn, bladder, lung bases. Musc. Bone- pelvis, sacrum, coccyx, lumbar spine, lower thoracic spine, lower ribs.
See organs shadows.
-other abn- stones, organs/masses, calcif of panc, vasc, nodes. Bones. Artefact. For bod.
Renal calculi- eg in ureter, partial stag horn. Chronic pancreatitis= calcif panc. Vas calcif eg aorta and iliac veins, atheroscler- abdo pain, worry isch gut. AAA mass bleed. For bod eg NG tube, stent.

Question 8

LO1: contrast.

Answer 8

-used to define hollow viscera- barium heavy met or water sol If risk perfor or leak.
-Comm swall for dismotil/achalasia LOS not open corr, OGD init.
Swall barium in upright/prone posit. See oesoph. Motil and anat lesion.
-doub contacts barium meal for stom and duod rare now as OGD and cam, poor sensit CA, carbex in stom prod gas. Small amnt barium given with effervescent grans or tablets to prod CO2 so double contrast btw barium and air.
-SI foll through but now MRI us. Barium swall. For gross anat SI.
-SI enema- tube through duod LOT dilute barium intro. For obstruc and stricture.
-Barium enema rare but only ever water sol. Pt low fibre diet 3D and colon cleansed with oral laxative. Barium and air insufflated by rectal catheter and doub contrast views obt of ent colon.
-all perf after overnight fast.

Question 9

LO1: US

Answer 9

ABDO US:

• sound waves gen image, freq above audib (20KHz), us 2-18 MHz. Cheap vs CT and MRI. Portable. User dep. good for gallst, panc head CA, dilat CBD. Appendix. Liver and PV.
• endoscopic US.
• US, CT and MRI used to define organs, thick bowel, messes, abcess, fistulae.
• US no rad, best for fluid filled lesions. Thick bowel no mucosal detail. Diag acute cholecystitis, AAA, appendicitis.

Question 10

LO1: desc imaging investig for GIT and abdo visc incl-
Plain X Ray (abdo and erect chest X Ray), contrast X Ray eg barium swall or enema or meal or water sol contrast studies, US, X sec imaging (CT and MRI), angiography.

Answer 10

-radiation- US and MRI v low. Abdo X Ray 1mSv bad if rep eg crohns and UC. Barium enema 7mSv now repl by CT colonosc. CT abdo/pelvis 10mSv.
Risks- CA, genet, dev risk to fetus. Background 1-3mSv. CT v comm so cause lot CA. More risk if yng having CT angiography.
AXR:
-up to eg T5. See rib, kidn, liver, gas in bowel dark, proper it fat stripe. Ant to post projection.
-Feats- bowel gas patt, soft tiss strucs, bones. Air, bowel, calcif (bones and stones).
-Bowel gas patt- any part of hollow tube visib if gas filled or gas and fluid filled, low dens gas acts as contrast, fully fluid filled not visib.
-Transit time- slow= colon, faeces or gas. Medium= stom, fluid and lot gas. Fast= SI, fluid not much air. Stom shows as dark.
-Abn gas patts- SI obstruc over 3cm. LI obstruc over 6cm, compet ileocecal valve over 9cm as reduced veins return= engorge, isch, perforate. incompet valve allow decompress of obstruc. Paralytic ileus. Volvulus. Toxic megacolon. Rule of 3’s (3,6,9).
-SI obstruc comm cause post surgical adhesions, wide on AXR.
Present- vom early, mild distens, absol constip late, colic.
Causes- adhesions. hernias-inguinal most comm, femoral, incisional. Tum. Inflamm.
SBO vs ileus often CT after XAR.
-LI obstruc soft tiss, most comm cause in ad is CA mostly rectum adn sigm. Compet IC valve if no gas in SI. Leave= closed loop obstruc= pop.
Present- vom late and faecular. Distens sig. Dull pain. Absol constip early.
Causes- colorectal carcinoma. Divertic stricture. Hernia. Volvulus. Pseudo obstruc.
Concern with compet IC valve. Like CT wth contrast next.
-volvulus- twist arnd mesenteric. Enclosed bowel loop- dilat, perfor, isch. Sigm comm, cecal and TC rare, only if anat defect.
Sigm volvulus- starts LIF, coffee bean sign tow RUQ- huge dilated sent loop, dilat proximal bowel If obstruc. Often isch.
-inflamm and infec- AXR may show acute or chronic changes. Mucosal thickening, featureless colon, bowel wall odema.
-toxic megacolon- acute deter with UC, colitis, occas crohns. Colonic dilat no obstruc. Odema. Pseudopolyps islands norm mucosa, rest sloughed. Us yng, need fluid, AB, colectomy if not rep fast.
-lead pipe colon- loss haustra, UC chronic inflamm. Risk CA.
-thumb printing- oedematous thick haustra, thick wall. Active inflamm- often UC, can see in other odema.
-fecal loading in constip.
-plain X Ray us for acute abdo.