Abdominal Radiology 2 Flashcards
CT scan Abdomen/Pelvis
- Most common procedure for abdominal pathology - “answer machine”
- IV contrast- vascular structures, organs
- Oral contrast- allows differentiation of bowel from other abdominal tissues
- Rectal contrast – colon
- Anatomy and level of slice – key
- CONTRAST, KIDNEYS, CREATININE
- Mesenteric or local sign of inflammation: “fat stranding” - can only be found on CT
- Fluid collections
CT abdomen and pelvis
-Base of lungs to femoral heads
-As you click through, what level are you at?
What is coming into view at that level?
Imaging the Intestines/Colon: Colonoscopy/CT scan
- Bowel Obstruction - +/- Plain Film/CT w/ IV con
- Bowel Ischemia - CT w/ oral and IV con
- Diverticulitis - CT w/ oral and IV con
- Colitis - CT oral and IV con/Colonoscopy/Barium (Ulcerative Colitis, Crohn’s Disease, TM: emergent vs non-emergent)
- Colonic polyps - colonoscopy, barium
- Tumors – Colonoscopy, CT w/ oral and IV con
Small bowel obstruction on CT
-Dilated, fluid-filled small bowel -Thickening of bowel wall -Air-fluid levels -CT best, most sensitive test for site of obstruction and cause -Radiologist to confirm
Large bowel obstruction
- Huge, dilated loops
- Haustra
- SB collapsed
- LBO on CT
- CT best for site of obstruction
Diverticulosis
-Large bowel
-Air-filled “outpouchings”
-At edge of bowel wall
-No fat stranding to suggest
inflammation
Diverticulitis
-Inflammation, infection or abscess of diverticuli
-Sigmoid location
common
-Local fat-stranding, thick, edematous bowel wall
Target sign on CT
DDX: -Crohn’s Dz -Ulcerative Colitis -Ischemic Bowel -Intussusception
Appendicitis
- Children – Ultrasound first (Wall thickness > 6 mm, Non compressible appendix)
- Adults- CT abdomen/pelvis with IV contrast (only) (Edema, inflammation (fat stranding), Dilated appendix > 6 mm diameter)
- Adults - Ultrasound - thin, pregnant (Non-compressible, >6mm diameter)
- Classic location
- Thickened wall
- Peri-appendiceal fat-stranding
- Appendolith
- Dilated >6mm: US
- Rupture? Abscess?
Hernias on CT
- Where are these hernias located?
- Fat stranding, inflammatory changes may indicate strangulation
Pancreatitis
- Pancreas crosses the midline
- ETOH, Rx drugs, viruses, gallstones, etc
- CT - oral and IV best
- ULS the biliary tree if suspect pancreatitis (Gallstone Pancreatitis)
- ERCP/MRCP (Gallstone pancreatitis, ERCP itself can precipitate pancreatitis
- Gallstone pancreatitis: stone in common bile duct that obstructs Ampulla of Vater and lodges in Spinchter of Odi, blocking pancreatic bile, enzyme discharge
The abdominal aorta
- Identify it on all CT’s
- Located just superior to vertebral body in axial view
- Follow it to the bifurcation
- Size?
- Calcifications?
- Contrast in lumen uniform?
pneumoperitoneum on CT
- Air or gas in the peritoneal cavity
- CT – (best test) “double wall sign”, falciform ligament
CT of Biliary system
- Where is the problem?
- Ultrasound - the first test
- ERCP/MRCP useful
- CT is not the first test for diseases of the biliary tract
- CT biliary tract findings incidental or for extent/other organ involvement
- CT best for emphysematous cholecystitis
Gallbladder on CT
-Cholecystitis (Enlarged, thickened wall, Fat stranding surrounding GB)
-Emphysematous Cholecystitis
Air around gallbladder (Infection by gas-producing bacteria, NOT seen on ultrasound!)
-CT is less sensitive for identifying gallstones than ultrasound and is NOT the initial test of choice.
-Air is the enemy of ultrasound!
Abdominal free fluid - CT
-Clinical scenario essential.
-Radiologist determines what
the fluid on CT likely is, using Hounsfield Units, if there is a question.
-Clue: look around liver and spleen
GU tract - kidneys/bladder
- Ultrasound – bladder (retention), kidney (hydronephrosis, parenchymal kidney disease/renal failure)
- CT scan best for renal/ureteral stones - no contrast***
- CT is best for hydroureter
- CT far superior for: Polycystic kidney, Renal cancers, Renal trauma
- **CT without contrast remains the test of choice for kidney stones – but that is shifting. IV contrast may camouflage the stone itself, right? Now, the thinking is that a CT with IV contrast will pick up the clinically relevant consequences of a stone - ie., renal ouflow tract issues: filling defects, hydroureter and hydronephrosis – and give us much more information about the abdomen and pelvis in the meantime, to help with the DDx. Seeing the stone itself is not as important as seeing the effects. This thinking is institution specific – not yet generally accepted.
Female Pelvic Imaging
- Ultrasound – first, best test (Uterus, ovaries, adenexa, pregnancy – all other dx’s same w/u)
- Formal ULS (by trained tech) of pelvis common (Usually follows abnormal bedside US study, Definitive, GYN wants a formal or does their own, Bladder full transabdominal, bladder empty transvaginal)
- Pregnancy (>12 weeks and beyond: Transabdominal, <10 weeks: Intravaginal probe)
- Ovarian pathology (really hard to see unless formal) (Transvaginal exam for ovaries/adenexa)
- Upreg before CT scan (or anything with radiation)
Female pelvis imaging: transabdominal ultrasound
- Low frequency curvilinear probe
- Longitudinal and tranverse views
- Identify bladder
- Identify uterus
- Normal endometrial stripe: central, white
- Myometrium – body of the uterus
- Cervix on longitudinal
- Can identify IUP at 7wks (in most)
female pelvis: transvaginal
- Useful to identify early pregnancy as early as 5-6wks gestation
- Best for ectopics
- Best for ovarian/adenexal pathology
- Bladder empty or partly filled is best for transvaginal ultrasound
- Arrow: specific footprint for transvaginal probe
Normal Uterus: transvaginal
-Transvaginal views: Identify endometrial stripe, Myometrium, Cervix (longitudinal)
OB Ultrasound
In ED (Is there a clear IUP? Dates match size? Fetal heart motion?) -In OB practice (Development, Amniotic fluid, placenta, Gender, Complications)
Early Pregnancy - first signs
Is there an IUP?
-Critical if suspect ectopic
On transvaginal US, first signs of an IUP:
-at 4-5wks gestation:
Gestational sac visible
Double decidual sac
-at 5-6wks:
Gestational sac plus Yolk sac:
Possibly see early fetal pole
-at 6-8wks:
Gestational sac plus:
yolk sac, fetal pole
By 7-8wks: fetal pole and cardiac activity should be present
- Gestational sac: clear, well defined anechoic area within the uterus
- Yolk sac: round, clearly visible, circular anechoic structure within the gestational sac
- Fetal pole: echogenic, usually oval structure within the gestational sac – the early fetus
Early IUP: transvaginal
Heterotopic pregnancy: 2 or more simultaneous pregnancies with separate implantation sites, one of which is ectopic. Incidence: 1:10,000 spontaneous conception, 1:1,000 assisted reproduction (fertility treatments)
