GOAL!
Finding
Case 2
CASE 3
- M/85
- Smoker for 10 years
- Admitted for Abdominal pain at LLQ
- -Bowel obstruction
- Vomited clear fluid
- Poor appetite
- F/53
- Diarrhoea
- Change of bowel habit 3 months
- Occasional central abdominal pain
- Sigmoidoscopy done: view partially obscured.
- Nothing abnormal detected
Prone
Supine
D/w patient and wife about abd pain + constipation
agreed for CT colonoscopy
Prone
Distal descending colonic mass highly suspicious
CA Colon
CT colonography was failed
A enhancing mass lesion is detected at distal descending colon,
(4.4x6.0x4.7cm)
1.2x1cm with a long thin stalk, located in sigmoid colon.
FINDING
Patient was incontinent to inflated rectal gas->the colon could not be distended
1.5x1.1cm with a long thin stalk, located in anterior wall of mid ascending colon.
Supine
Advantages of Tagging
FINDINGS
Improve sensitivity and specificity
Summary
VC with Tagging NOT ready applicable:
- Improves polyp detection in " drowned " segments
- Avoids false positives by tagging stool
VC is an alternate to colonoscopy for colonrectal screening
Deliver of the Oral contrast agent ?
From pharmacy? From DIIR Dept?
Case 1
- Improved contrast difference between the non-tagged lesion and the tagged stool.
Optimal distention of colon and bowel preparation improve detection of lesions in VC
Protocol of tagging?
Barium? Gastrografin?
Administration of oral contrast agent ?
Improve patient compliance
CASE SHARE
CO2 is probably better than room air
- F/47
- Father has Ca colon dx at age around 60s
- Fresh PR bleed since last year
- normal bowel habit
Patient's co-operation?
- Laxative- free or patient-friendly preparation method (Future)
Follow the instruction of the appointment sheet?
Tagging improve diagnosis and shorten the reading time
Tagging protocol
Alternative techniques
Before 10am- a days before the CT
After 10am- a days before the CT
WHY using tagging ?
12noon- a days before the CT
Tagging
1st bottle 50mL of Gastrografin mixed with a glass 50mL of water
Despite an intensive cleansing of the colon, both residual stool and fluid in the colon cause diagnostic difficulties
8pm- a days before the CT
2nd bottle 50mL of Gastrografin mixed with a glass 50mL of water
Supine scan shows two lesions in the transverse colon. (arrows)
Prone scan shows the lesions in the transverse colon in an apparent different position (arrows)
Labelling of faecal residue/ fluid in the colon
4 hours before the CT
BookMark
Stool? Polyps?
Aim of bowel preparation with tagging :
1) improving diagnosis;
2) improving patient compliance.
Measure the distance bet lesion and rectum
-help the further diagnostic and treatment of OC
Tagging
The oral ingestion of positive contrast material
Tagging preparation of VC in PWH
Stool tagging
Fluid tagging
Barium
Iodine
Trial period: From March to July 2014
- the residual stool/ fluid have a hyperdense or white aspect on the 2D CT images.
NO. of Cases: 16 (1 fail)
Oral contrast agent: Gastrografin
(Iodine based)
Data Post-processing
Fluid tagging
Stool tagging
3D Transparency View
Start deflating the rectal balloon 40s before contrast CT scan
MPR
Thick rectal balloon catheters can hide rectal lesions.
Advantage Workstation 4.5; GE Medical Systems
Software:
Advantage CTC Pro 3D EC
3D Endoscopic Fly-Through
360 degree virtual dissection
- Contrast CT Abd & Pel
- Contrast: 100ml OMN300
- Injection rate: 2.5ml/sec
- Delay 70 s
Preset pressure : 18-20mmHg
Flow rate:
3L/min
Open the External desufflation tube port
Allow the desufflation of CO2 to the outside of the device to avoid:
- > overpressure in the colon,
- > backflow of fluid into the device, thus avoiding any risk of damage or contamination.
set pressure increase:
2mmHg
Max: 25mmHg
Rotation time
Thin slice thickness
Normal curent
extracolonic pathology
Scan time
mAs
Decubitus position scanning can be added
Better
3D endoluminal images
2D MPR images
Radiation dose
Affect the evaluation of the colon,
Respiratory & motion artifacts
image noise
Discussion
Prone CT Abdomen & Pelvis (non-contrast)
Yee et al, Radiology 2003
Before insert the rectal tube, scout view are taken to check the presence of extraluminal gas
VC Procedure:
Both prone and supine images are obtained
-> higher sensitivity
- Near 2L CO2 insufflated, Patient is moved into a PRONE position
Dual Position???
- lied in lateral decubitus position.
- A rectal tube with balloon was inserted and conncected to CO2 insufllator.
- Inflated the balloon with water/NS to hold the postition securely .
Allows redistribution of air, stool and fluid
Optimal distension of different segment of colon can be achieved in different position
Scout image: assess degree of colonic insufflation
sensitivity for polyp detection.
64-slice GE Lightspeed VCT scanner
Turn to SUPINE position
Scout image:
assess degree of colonic insufflation
Prone
Supine
Room Air
Carbon Dioxide
- Additional equipment costs.
- Easiest and cheapest method
- Readily available
"Colon insufflated"
When the volume of CO2 insufflated is greater than 1,1l and according to the flow and pressure variations.
Administration set :
- long 3 way catheter
- large bag for effluents
- with “Y” connector for external release of overpressure
CO2 Insufflator in PWH
Patients may experience severe pain because air
- A large component of nitrogen
-no active diffusion across the bowel wall
-distension feeling up to several hours
Better tolerated and decrease patient discomfort
because CO2
- resorpt through the colon wall and blood rapidly
-exhaled from the lungs
"OVERPRESSURE"
When the intra-colon pressure exceeds the pressure setpoint by 2 mmHg for a duration of 3 s
Manually
Automaticaly
After 5 litres of CO2 have been insufflated
the device displays PAUSE in the alarm field and stops the insufflation
of gas .
Restart the insufflation by pressing of the RUN button
- Usually using hand pump
- Insufflation is continued until the operator believes that the colon is optimally distended
- most experts judge this by noting patient tolerance
Use of CO2 pump insufflator
-pressure-sensitive
-insufflating CO2 at controlled flow rates and pressures
-maintains a continuous preselected pressure
2014 July: Demotration
2014 Dec: Apply
Cases: > 150
Colonic insufflation
The utility of spasmolytics for Virtual colonography is
Use of spasmolytics
Controversial
- Relax the bowel wall
- Minimize peristalsis.
- Makes the examination more comfortable.
No sinificant improvement of colonic distention
(Morrin et al. 2002).
Did not improve the polyp detection on VC
(Rogalla et al. 2005)
(Yee, Radiology 1999)
Glaucoma ?
Cardiac ischaemia?
Automated / Carbon dioxide
Source:Appointment for Barium Enema, Department of Radiology, NTWC
https://gateway.ha.org.hk/f5-w-687474703a2f2f6e747763636f727069733031$$/dr/Appointment%20Sheet/Fluoroscopy/TMH/TX2002_e_-Ba%20Enema-Loopogram-1213%20_Appendix_.pdf
Yes
No
Buscopan
Glucagon
Manual/
Room air
Drawbacks
Cost
Relaxes the ileocecal valve
reflux of gas into the small bowel
colonic distention
Retention time of gas and cramping (room air)
Colonic Distension
Collapsed segment/ Under distended segment of colon:
- Can mimic Ca colon
- Make the folds appear large and more bulbous
- Lesions can be missed
Bowel Preparation
On the exam day
Bowel preparation
- Admit in the SACC in the morning on the same day of exam to take Klean-Prep following the instruction
Remaining pools of fluid can hide polyps
Residual solid stool
- misdiagnosed as a polyp
- obscure true colorectal polyps and even cancer
Before Exam:
- Low residue diet for 2 days.
- No vegetables or fruit intake for 2 days
- Fast for at least 4 hours (except water or broth)
Klean-Prep®
---a balanced mixture of polyethylene glycol 3350 (PEG 3350) and electrolytes
---acts as a bowel cleansing agent
Technical factors:
---very effective in clearing solid material
--- leaves a large amount of residual fluid
supine
POLYPS?
What are the key element for a high-quality Virtual Colonoscopy examination
Virtual Colonoscopy (VC)
Virtual Colonoscopy (CT Colonography) in screening the Colorectal Cancer
Optical Colonoscopy
Every 5 years
Pros:
- Sensitivity : 93% , Specificity: 97% (for polyps >10 mm)
- Useful in patient with incomplete OC
- Lower cost than OC
- Better tolerated by patient than OC and DCBE
- Lower risk of perforating the colon than OC
- Staging and extra-colonic findings
Cons:
- Ionizing radiation
- Colonoscopy needed if polyps were found
- Every 10 years
- Gold standard screening
- Scope length of 1.6m
- Can usually view entire colon
Virtual Colonoscopy
Virtual Colonoscopy
Pros
- High sensitivity :
- 94%>10 mm diameter , 87%- 6–9 mm, 73% <5 mm
- Provides diagnosis and therapy
About Virtual colonoscopy...
Cons
- Invasive
- quality is variable
- most expensive
= CT Colonoscopy (CTC)
1993: Introduced by Dr. David Vining
1996: The first clinical use of VC
- Use helical CT and advanced three-dimensional graphics software to produce
---Axial,
---2D reformattd image and
---3D endoluminal images of the colon
- To diagnose colon and bowel diseases, including polyps, diverticulosis and cancer
Screening Options
- The AGA Institute supports CTC as a promising screening test for colorectal cancer, which we believe will be in widespread clinical use in the near future.
"AGA Supports New Guidelines Favoring Tests That Prevent Colorectal Cancer ", March 5, 2008
Colorectal Cancer SCREENING
- Fecal occult blood test (FOBT)
- Flexible Sigmoidoscopy (FS)
- Double-Contrast Barium Enema (DCBE)
- Optical Colonoscopy (OC)
- Virtual colonoscopy (VC)
Hong Kong Top Ten Cancers in 2012
Source: Hong Kong Cancer Registry -http://www3.ha.org.hk/cancereg/
Fecal occult blood test (FOBT)
Double-Contrast Barium Enema
- Stool test
- Every 1 -2 year
Pros:
- Low cost
- No bowel preparation
- Simple test
Cons:
Flexible Sigmoidoscopy (FS)
Pros:
- Evaluation of the entire colon
- Widely available
- Low cost
- Every 5 year
- Scope with 60cm in length
- The range of examination: the lower portion of the colon
- sensitivity :78%, specificity: 84%
Pros:
- Provides diagnosis and therapy
Cons:
- Bowel preparation is needed
- Invasive
- Views only about a third of the colon, miss > 50% advanced proximal
- Less sensitive to colonoscopy
Cons:
- Low sensitivity (48% >10mm)
- Radiation
- Colonoscopy needed if polyps were found
Lui Ho Shan, Rad II
Risk Factors
Age>50
Anatomy of colon
Colorectal Cancer
Colon Polyps
~Sessile polyps-mushrooms without a stalk
~Pedunculated polyps- mushroom with a stalk
-may have a higher risk of becoming a cancer.
- Cancer that occurs in the colon or rectum
- Usually develops from polyps
- One of the most preventable cancers!