11. Patient Preparation
Nil Per Oral from 5-6 hours.
Use laxative as well as water enema for colon examination.
First explain all about examination and its complication to
patient.
Take informed consent from patient or his/her close
relatives.
Radiopaque material should be removed from area of
examination.
CT Procedure of Abdomen and Pelvis
11
12. Contrast Media
Oral contrast: 750-1000ml of 1-2% Barium or water soluble
CM/plain water/ Air.
Rectal contrast: 500-750 ml of 1-2% Diluted iodinated CM/Plain
water/ Air or CO2.
IV contrast: Non ionic monomer( Iohexol, Ioversol,
Iopromide) 300-350mg or Nonionic Dimer. Dose: 100 to
150 ml.
IV contrast is given by auto injector.
CT Procedure of Abdomen and Pelvis
12
13. Contrast Media
Never give barium as a oral contrast in case of GI
perforation.
Do not give positive oral contrast if vasculature needs to be
demonstrated by MIP.
Now a days plain water is commonly used as oral contrast
in CT examination of abdomen.
CT Procedure of Abdomen and Pelvis
13
14. Bolus Tracking
Technique used in CT to
visualize vessel more clearly
by use of Radiopaque CM
into patient.
The volume of contrast is
tracked using ROI at a
certain level and followed
by CT once it reaches this
level.
Generally the threshold
value is 150 HU in
abdominal aorta.
CT Procedure of Abdomen and Pelvis
14
15. Technique for Routine Abdomen and Pelvis
Firstly, patient takes two third oral contrast from ½ to 1
hour for upper abdomen and 1 to 2 hour for lower
abdomen before examination.
Then , one third oral contrast just before examination.
Patient position: Head first, supine with arms extended
above the level of head.
CT Procedure of Abdomen and Pelvis
15
16. Technique for Routine Abdomen and Pelvis
CT Procedure of Abdomen and Pelvis
16
Topogram position/landmark: AP,
from 2” above the Xiphisternum to 2”
below the Symphysis pubis.
Mode of scanning: Plain and
enhanced in most of helical and in
some where axial.
Scan orientation: Craniocaudal from
dome of diaphragm to Symphysis
pubis.
FOV: Variable- Just fitting the
abdominal wall including sofr tissue.
Contrast administration: As mentioned
above : Oral, Rectal and I/V.
17. Technique for Routine Abdomen and Pelvis
Injection rate: 2-3 ml/sec
Scan delay: 40-60 sec
Slice thickness: 3-5 mm
Slice interval : 1.5-2.5 mm
Recon algorithm/Kernel:
Smooth medium
3D reconstruction: MPR, MIP
CT Procedure of Abdomen and Pelvis
17
18. Modification in CT Technique of Abdomen
There are some modification on CT technique depend upon
the pathology of different part inside abdomen.
This modified technique are described as follows:
CT Procedure of Abdomen and Pelvis
18
19. CT of Stomach
Plain water is used as oral contrast rather than the positive
oral contrast.
About 500-600 ml plain water is given just before the
examination.(distention of stomach).
Do the plain CT.
CECT in venous phase in supine.
Then do CT in prone, Rt. or Lt. Decubitus.
CT Procedure of Abdomen and Pelvis
19
20. CT of Stomach
CT Procedure of Abdomen and Pelvis
20
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
21. Hepatic CT
Plain water is used as oral contrast.
Triphasic CT is performed for liver pathology.
Arterial phase- hepatoma or focal nodular disease are
detected.
Portal venous phase-
Delayed phase- hemangioma are clearly seen.
Area of scan from dome of diaphragm to iliac crest.
CT Procedure of Abdomen and Pelvis
21
22. Hepatic CT
CT Procedure of Abdomen and Pelvis
22
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
23. Biliary CT
Plain water is used as oral contrast.
Role of plain CT is to detect stone.
Area of scan from dome of diaphragm to iliac crest.
Cholangiocarcinoma are detected in delay scan.
CT Procedure of Abdomen and Pelvis
23
24. Biliary CT
CT Procedure of Abdomen and Pelvis
24
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
25. Biliary CT
CT Procedure of Abdomen and Pelvis
25
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
26. CT of Pancreas
CT Procedure of Abdomen and Pelvis
26
Plain water is used as oral contrast media which help to
distended C loop of duodenum.
No oral contrast in case of pancreatitis.
Area of scan from dome of diaphragm to iliac crest.
27. CT of Pancreas
CT Procedure of Abdomen and Pelvis
27
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
28. CT of Pancreas
CT Procedure of Abdomen and Pelvis
28
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
29. CT of Small Intestine
In general,
Positive oral contrast about 1000 ml from 1 hrs.
Non enhanced CT.
After I/V contrast 100-150 ml.
1. Arterial phase- 25 to 30 sec
2. Venous phase- 55 to 60 sec
Now we perform CT Enteroclysis/Enterography for small
intestine.
CT Procedure of Abdomen and Pelvis
29
30. CT Enteroclysis
In CT Enteroclysis, oral contrast is infusioned via
nasoenteric intubation.
Various type of oral contrast used include water, water &
methylcellulose, lactulose.
Nonenhanced CT perform in case of hemorrhage.
CT Procedure of Abdomen and Pelvis
30
31. CT Enterography
In CT Enterography, oral contrast per orally.
Various type of oral contrast used include water, water &
methylcellulose, lactulose.
About 1- 2L from ½ to 1 hours before scanning.
CT Procedure of Abdomen and Pelvis
31
32. CT Enterography
I/V cm is given at rate 3 ml/s to
obtained bowel enhancement.
In MDCT, 1 mm or less slice
thickness is obtained.
Generally do single phase(45-50s)
and sometime multiphase.
CT Procedure of Abdomen and Pelvis
32
Source: CT & MRI of The Whole Body-
John R. Haaga, Fifth Edition
33. CT Colon and Rectum
In general,
Positive oral contrast about 1000 ml from 2 hrs and
rectal contrast air/plain water.
Non enhanced CT.
After I/V contrast 100-150 ml.
1. Arterial phase- 25 to 30 sec
2. Venous phase- 55 to 60 sec
Now we perform CT Colonography or virtual colonoscopy.
CT Procedure of Abdomen and Pelvis
33
34. CT Colonography
Bowel preparation :
colonic purgation- sod. Phosphate and magnesium
citrate.
fecal and fluid tagging- is method of labeling of
residual fecal and fluid remaining on colon by using
Radiopaque contrast agents.
The contrast agent is orally administered at each meal,
typically the day before the CT Colonography.
Colonic distention:
room air is used rather CO2 because rapid absorption
and painful.
CT Procedure of Abdomen and Pelvis
34
35. CT Colonography
Inj. Buscopan20mg is given before air insufflations.
Scanning in supine and prone position has shown a
superior colonic distention with slice collimation < 3mm.
I/V contrast media is generally not required.
CT Procedure of Abdomen and Pelvis
35
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
36. CT for Adrenal Gland
Area of scan from dome of diaphragm to L3 level.
Plain CT.
After IV contrast media 125 ml at rate 3-4 ml, do following
phase.
Arterial phase- 20 sec
Parenchymal phase- 50-60 sec
Delayed phase- 10 to 15 min
Slice thickness- 3 mm
CT Procedure of Abdomen and Pelvis
36
37. CT for Adrenal Gland
CT Procedure of Abdomen and Pelvis
37
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
38. CT for Kidneys
Area of scan from dome of diaphragm to Symphysis pubis.
Scan thickness- 1 to 3mm.
Non enhanced phase- Plain CT
Corticomedullary Phase- 25 to 70 sec
Nephrographic Phase- 80 sec
Excretory Phase- After 180 sec
CT Procedure of Abdomen and Pelvis
38
39. CT for Kidneys
CT Procedure of Abdomen and Pelvis
39
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
40. CT Urography
Now, CT Urography is another imaging technique for
urinary tract.
In CT Urography, Kidneys, ureters and bladder are better
visualized.
No need of oral contrast.
First do plain CT and followed by CECT.
CT Procedure of Abdomen and Pelvis
40
41. CT Urography
CT Procedure of Abdomen and Pelvis
41
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
42. CT Urography
CT Procedure of Abdomen and Pelvis
42
Source: CT & MRI of The Whole Body- John R. Haaga, Fifth Edition
43. CT Uterus/Ovaries
Oral contrast one hour before examination.
Rectal contrast just before examination.
Nonenhanced CT
IV contrast 300mg/ml about 100-150 ml.
Arterial Phase- 25 to 30 sec
Venous phase- 55 to 60 sec
CT Procedure of Abdomen and Pelvis
43
44. CT Technique for Abdominal Trauma
Oral contrast is still controversy .
Plain CT of Abdomen- to see hemorrhage.
Area scanned- from diaphragm to Symphysis.
Slice collimation- 2.5 to 3 mm.
CT Procedure of Abdomen and Pelvis
44
45. CT Technique for Abdominal Trauma
Thickness reconstruction- 5 mm
Volume of contrast -100 to 150 ml at rate of 2-3 ml/s.
Scan after 70 sec of onset of injection.
Delay scan after 3-5 min to see excretion from kidney.
CT Procedure of Abdomen and Pelvis
45
46. Film Printing Protocol
Generally 5x5 mm If required thin section.
Keep HU value on area of pathology both in Nonenhanced
and enhanced CT.
Multiplanar reconstruction(MPR).
3D VRT and MIP for vascular pathology.
Windows level and centre-350/50 for soft tissue and
2200/400 for bone.
CT Procedure of Abdomen and Pelvis
46
48. Department Protocol
Lower Abdomen Protocol
CT Procedure of Abdomen and Pelvis
48
S.N Diagnosis
Oral
Contras
t
Rectal
Contras
t
NCCT
(5x5
mm)
CECT
(5x5
mm)
Thin
section
(3x3 mm)
MPR
(Sagittal
+
Coronal)
3D
1. Colonic
pathology
√ √ - √ √ √ -
2. Gynaecolog
y pathology
√ √ √ √ √ √ -
3. Pelvic
tumor
√ √ - √ √ √ -
49. Department Protocol
CT Procedure of Abdomen and Pelvis
49
1. Unless particular small bowel pathology is suspected or
specified, plain water should be given as oral contrast for upper
GI and lower GI (colonic pathology).
2. For colon, if no obstruction, air should be given as rectal
contrast.
Triple phase:
Arterial phase (20-30 sec), Portal Venous Phase (60-70 sec) &
Late Venous Phase (180 sec).
CT Urography: Delayed films at 5 minute.
1. Unless specified, all films to be given as axial 5x5 mm along with
Sagittal and coronal MPR
2. Films for CT angiography: Axial, MPR & 3D
3. Contrast Dose:
a. Adult patient: 100 ml contrast with concentration of 300mg
Iodine/ml.
b. Children: 1.5 ml of contrast per kg body weight.
50. Summary
CT has still superior role for abdomen imaging to detect
pathology despite of adverse effect and radiation effect.
Never forget to see or ask history of patient under going
CT examination of abdomen.
There are variations in CT protocols of different centre.
Always use auto injector for I/V contrast media injection if
possible.
CT Procedure of Abdomen and Pelvis
50
51. References !!!
CT Procedure of Abdomen and Pelvis
51
CT and MRI of whole body, Johan R. Hagga, Fifth edition.
CT and MRI Protocol, Satish K. Bhargava
CT Teaching Manual, Matthias Hofer, Third edition.
Step by Step CT scan, Karthikeyan & Chegu, First edition.
52. Questions ???
CT Procedure of Abdomen and Pelvis
52
What are the contrast media used for CT Abdomen?
What is oral and rectal contrast media?
What is Bolus Tracking?
What are the indication for CT abdomen?
Describe the patient preparation for CT abdomen?
Mention the Protocol for Hepatic CT?
What is CT Urography?
What are the modification for CT Stomach?
Figure 31-1 A, High-resolution CT scan shows normal intrahepatic bile ducts (arrows) as linear water-density structures accompanying the portal vein branches. B, T1-weighted MR image after the administration of gadobenate dimeglumine demonstrates the intrahepatic bile ducts (arrows), with biliary excretion of contrast material located anterior to the portal veins.
Figure 35-1 Normal anatomy of the pancreas. A to I, Axial CT sections of the pancreas from superior to inferior. A and B, Superior portion of the body of the pancreas (B) with the splenic artery (Spl.art) posterior to the body. The splenic artery is a branch of the celiac artery (CA), which in turns arises from the aorta (A). IVC, inferior vena cava. C and D, The oblique orientation of the long axis of the pancreas is seen with the tail (T) extending from the hilum toward the midline of the body (B). The body continues as the neck (N) anterior to the portal vein (PV) and superior mesenteric artery (SMA), which in turn continues as the head. E and F, The head lies in the C loop of the duodenum, bound superiorly by the bulb and medially by the second part of the duodenum (2nd). The common bile duct is seen as a low-density structure posterior to the head (H) of the pancreas (arrow in F). Branches of the pancreaticoduodenal arcade are seen around the head of the pancreas. G and H, The head lies anterior to the inferior vena cava (IVC) and is bound medially by the superior mesenteric vein (SMV). The head turns around and inferiorly to the triangular uncinate process (U), which lies posterior to the superior mesenteric artery (SMA) and vein. I, The inferiormost portion of the uncinate process is seen anterior to the superior mesenteric artery and vein.
CT scan for enterography should be performed using a thin-slice thickness to allow high-quality coronal or sagittal images as well as three-dimensional reconstruction. With the current scanners that are already widespread in use (i.e., 16-detector or 64-detector MDCT), 1-mm slice thickness or less is easily obtained without motion artifact. Intravenous contrast injection at a rate of 3 mL/sec or greater is recommended to obtain good bowel wall enhancement. Optimal scan delay depends on the indications. In most cases, particularly in the evaluation of Crohn's disease and bowel obstruction, single-phase imaging with a scan delay of approximately 45 to 50 seconds, the so-called enteric phase wherein the bowel wall enhancement is maximized, is most appropriate.[659,][771] In cases of suspicious gastrointestinal bleeding or ischemia, multiphasic scans are necessary. In cases of suspicious gastrointestinal bleeding, nonenhanced scan may also be helpful in the detection of high-attenuating acute hematoma.
Figure 30-180 Fecal tagging using orally administered barium. A, Three-dimensional endoluminal view of CT colonography shows an 8-mm polypoid structure (arrowhead) on a haustral fold of the sigmoid colon. B, Two-dimensional transverse view (width, 1500 HU; level, −400 HU) of CT colonography clearly shows very high attenuation of the polypoid structure (white arrowhead), confirming a piece of tagged stool. Another piece of tagged stool is noted in the sigmoid colon (black arrowhead).(From Park SH, Yee J, Kim SH, Kim YH: Fundamental elements for successful performance of CT colonography (virtual colonoscopy). Korean J Radiol 8:264-275, 2007.)
Figure 40-1 Normal adrenal glands. A, Typical location and appearance of the right gland (black arrow), which is shaped like an upside-down V. On the left, the gland is located in a triangle bounded by the pancreas, aorta, and kidney. It is shaped like an upside-down Y (white arrow). B, Magnification view of the same scan shows the medial (white arrows) and lateral limbs (black arrows) of the gland to better advantage. The limbs are thinner than the apex of the gland.
Figure 41-5 Normal CT anatomy. A, The corticomedullary phase demonstrates dense enhancing cortex with minimal enhancement of the renal medulla. B, After a brief delay, the parenchymal enhancement becomes uniform, resulting in the nephrographic phase; in the late nephrographic phase, calyces may be opacified.
Figure 41-12 Normal CT urography. Coronal maximum intensity projection image of the CT urogram in the excretory phase demonstrates the opacified proximal and middle ureters.
Figure 41-13 Normal CT urography. Three-dimensional volume-rendered image of the excretory phase of the CT urogram demonstrates the kidneys, ureters, and bladder.