Contrast and protocols
Types of contrast:
#Oral contrast:
1-Gastrographen (+)
-Concentration: 2.5-3 % ،1000 (1 litter)/30ml
-It’sHyperdense
-Indication:
Obstruction
Perforation
Collection
Infection
2- Water (neutral 0)
-For any inflammation we used water
-Indication:
Crohn disease
Ischemia
Inflammation
# In bowel ischemia we should use
- Water
- Arterial (to see the blood vessels)
- Venous (enhancing the wall)
The water will absorbed quickly from the intestines, so we want to make it hyperosmolor for better distention of the bowl wall, we mix it with specific substancethen it will become thick
-Water+ Metamucilhyperosmolor
-Disadvantage:
The pt should drink 2 litters of contrast around 35-40 min before the exam, they cant tolerate it because its a lot , that why someone should be with them to make sure that they will drink it.
# Ovary.. We should give oral and gastrographen
-Theovarian CA usually metastasis to peritoneum and its appear as cystic metastasis.We want to distend the bowl so we can differentiate between them.
# Gynecases…Gastrographen
-(To differentiate between the tumor > bowel)
#GI (bowel).... Water
-(Water is better than gastrographen in GI ,, because the mucosal enhancement is better with water) gastro and the wall (ma ra7 yban shy klhombykonlonhom white, 3shan ketha ma ra7 nfrg)
#Rectal contrast:
-Mandatory in pelvic cases and colon (lazzm n36y)
-Any gyne case we should give
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#CT enterography:
Water & metamucele
-Induction:
Crohn’s disease
Small bowel CA
Abscesses
- used to diagnose crohn’s disease and determine its location, severity and complication ( aham shy)
-Its give us a good distention
#CT coly...: (not used anymore)
-Bynasojujnal tube, direct injection of water
-Its give us excellent distention
#CT colonography:
Mainly to assess the colon (polyps)
1-patient preparation
2- colon distention
3- scanning
Get rid of the stool by fecal tagging, mixing the stool with gastrographen
First we should give the patient low fibers diet for 3 days, the 1-daybefore the exam let the patientdrink gastrographen, then before 6 hours don't let hem eat anything
At the time of exam we pump a gas to the rectum by folly’s catheter
We should do the exam in supine and prone position (3shan al polyps ttgalb m3 al gravity)
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#Liver:
Triphasic liver
- Optional:C- .. To see calcification and fatty infiltration.
Arterial 30 - 35 sec
Venous 60 - 70 sec
Delayed 3 min. to characterize the lesion
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#Spleen:
Like the protocol of the liver
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#Kidneys:
Mandatory: C- without contrast
Arterial(cortico-medullary phase) 40 - 45 sec
Venous(nephrographicphase) 80 - 90 sec
- Optional: delayed ...to see tumor in collecting urinary system 7 - 10 min
# What is the most sensitive phase to look for focal lesion in the kidney?
-Nephrographic phase
Hematuria: ~painful... Stone> un enhance
~ not painful... Mass> 4 phasic
-non enhance, arterial, Portovenous, delayed
#Pancreas:
1- pancreatic mass
-Hyper or hypo vascular lesion both of them we can find it in the pancreas.
- late Arterial and venous (like the liver)delay time 40 sec
2- pancreatitis
-Early venous phase 60-70 sec, because its hypervascular we use water and gastrographen
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#Adrenals:
Adrenal mass: non enhanced, venous and delayed
**The most common tumor in the adrenal gland is the adenoma.
Adrenal adenomas have two properties that differentiate them from non-adenomas. (1)
1. high intracellular fat and will be of low attenuation on unenhanced CT.
2. Adenomas rapidly wash out contrast.
# C- adrenal:
- -ve (no mass) …. Go and check
- +ve lesion (according to the density)
- <10 HU…. Confirm adenoma
- >10 HU…. 2 option: 1- fat poor hematoma
2- malignancy
To differentiate between them: we should do dynamic scan:
* venous 60 -70 sec
* Delayed 10-15 min
-Adenoma washout the contrast in short time 60,but the malignancy takes time to washout the contrast 60.
-Absolute washout equation: (sensitive and specific about 95%)
Venous enhance - delayed E - D
______x 100 ______x 100
Venous enhance - unenhanced E – U
- <20 - HU. …mylolipoma (Bone marrow and fat)
Benign
…………………………………………………………………………………..
#CT cystogram:
-Dilution contrast 4-5%
-Direct injection of contrast to the urinary bladder by follys catheter ( by gravity y3ne n3l8 al contrast ) not by hand ,, 3shan law fe injury ma nzedaha
#CT urogram:
Inject i.v contrast then scan after 5-10 min
-Disadvantage: Distention poor and no pressure
-Advantage: good for ureter, renal pelvic and if we want to assess if the stone is inside the ureter or outside.
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#I.V contrast:
-Dose 1 -1.5-cc/ kg
120 (split injection, 1 scan better than 2 )
- 50 cc…. Wait for 10 min
- 70 cc …. Scan at 70 sec
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#Limited study due to lack of contrast::
GFR >60-give contrast
GFR between 60 & 45 give contrast with fluid oral or iv
GFR <45 don't give
# If the pt is on dialysis: always give because the kidney is not working , but if there is small amount of urine output don't give hem contrast; they live more if they urinate so don't kill the kidneys.
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#Contrast material administration:
Traumatic cases and stroke .. Don't give
# Space occupying lesion in the brain:
Known case of tumor... C+ with contrast
If they dontknow( ER case) .... Plain C- without contrast
#CTA (angio) carotid circle of willies
#Diseases:
-Assessment::portovenouswithout oral or rectal
We chose venous , if we want to know the relation with other organs
-Beast & lymphoma ... Arterial and venous
-Crohnsdisease:: oral contrast , gastrographen or water
-Bowel obstruction:: water contrast , to asses wall
-Ischemic bowel: arterial ,portovenous with oral
-Stomach and duodenum:: 2 cups on table and venous
-Colon CA :: venous and rectal
-Colon:: oral and rectal
-Pelvic organ:: oral and rectal
#Delayed::
-Liver: 3 min
-Kidney: 15 min
-Pancreatitis: 45 sec
-Pancreatic mass: 45 sec after bolus detection
-Ischemic bowel: 30-35 sec
-Renal mass:45 sec
There are several tumours which are noted to causehypervascular metastases. The list includes:
•renal cell carcinoma
•breast cancer:
homogenously hypervascular liver metastases from breast are considered rare3
•neuroendocrine tumours:
carcinoid tumours2
•thyroid carcinoma
•melanoma
•hepatocellular carcinoma
•choriocarcinoma
•leiomyosarcoma
•hypervascular liver lesions