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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

Shorten the reading time

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

Normal breakfast

After 10am- a days before the CT

Low residue diet

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

Fasting

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

Supine/

After contrast

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

Prone/

Pre contrast

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

  • Common

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

  • Less availability

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)

Insufficient

Adequate

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?

  • Bowel preparation

  • Colonic distention

  • Use of spasmolytics

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

Every 5 years

  • Stool test
  • Every 1 -2 year

Pros:

  • Low cost
  • No bowel preparation
  • Simple test

Cons:

  • Poor sensitivity

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

  • Abnormal growth tissue
  • Polypoid: Raised polyps

~Sessile polyps-mushrooms without a stalk

~Pedunculated polyps- mushroom with a stalk

  • Adenoma

-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!

  • Non-polypoid: Flat polys

There is no significant (6mm or larger) polypoid growth in colon

Incidental finding: 2 cm polyp in the mid small bowel.

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