Mehdi Cadi CT colonography Jfim Buenos-Aires 2017
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New technique which will become a second morphologic method to explore entire colon and replace definitively the barium enema
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Mehdi Cadi CT colonography Jfim Buenos-Aires 2017
- 1. • Dr Mehdi Cadi • Radiology Dpt RPO Neuilly sur Seine 92200 France JFIM Buenos Aires 2017 CT colonography
- 2. female male female and male PROSTATE 56841 56841 BREAST 48763 48763 CRC 19926 23226 42152 LUNG 11284 28211 39495 2 New cases / per year (FRANCE)
- 3. Also called Virtual colonoscopy New technique which will become a second morphologic method to explore entire colon and replace definitively the barium enema
- 4. Bowel preparation Colonic distension, MDCT acquisition parameters Radiologist training for this new method
- 5. Liquid diet 24 hours before examination 300 ml Citrate Magnesium and 20 mg Bisacodyl (dulcolax®) If renal or cardiac insufficiency we substitute citrate magnesium with 2L Colopeg® (classical GI bowel prep)
- 6. Micropaque Scanner® (500 ml) for stool tagging Telebrix Gastro® (50ml) for fluid opacification
- 8. The colon is insufflated with automated CO2 Scout view is obtained to verify adequate bowel distention CT colonography is performed with the patient supine and prone in a cephalo-caudal direction. Mean time = 8-10 mn CT Colonographic technique
- 9. Repeated Supine scout view to obtain optimal colonic distension
- 10. 8-10 mn
- 11. 1.25 mm thick sections 1 mm reconstruction interval 120kv et 80 mAs pitch = 1.35
- 13. Optimal preparation of the colon
- 16. Left and right position
- 17. Solid tagging
- 18. 3D first approach (3D endoscopic view) vs primary 2D approach (axial images and MPR view) ? The choice is influenced by personal preference and available workstation
- 19. Review of 2D images with appropriate window settings ( -500, + 1500 UH) on “cine mode” and 3D endoscopic view for problem solving. Mean time = 10-14 mn 2D Approach
- 21. 8 mm tubular adenoma transverse colon
- 23. 3D first approach consists of performing a primary 3D endoluminal “fly-through” examination and correlating the results with findings from 2D images. Complete antegrade (from cecum to rectum) and retrograde(from rectum to cecum) 3D fly-through Mean time = 10-15 mn 3D approach
- 24. Fly through anterograde and retrograde
- 26. Colon map with: real-time position indicator Bookmarking Automated centerline Electronic fluid cleansing Translucency rendering Helpful 3D tools
- 28. semi automated center line with collapsed segments Supine Prone
- 29. Electronic Fluid Cleansing Pickhardt PJ, Choi JR. AJR 2003;181:799-805
- 30. Translucency Rendering Provides information on internal architecture Attenuation-dependent color and transparency Useful for rapidly excluding pseudopolyps on 3D view Reduce the number of 2D correlations necessary PJ Pickhardt et al AJR 2004;183, 429-436
- 31. Translucency PJ Pickhardt et al AJR 2004;183, 429-436
- 34. Radiology 1999; 212: 203-212 Christopher F. Beaulieu and Co. Blind areas at virtual colonoscopy
- 38. Residual fecal material vs polyp: Mobility Morphology internal attenuation
- 39. ProneSupine
- 40. Supine Prone 0
- 49. PJ Pickhardt et al AJR 2004; 183:1343-1347 Flat colorectal lesion in asymptomatic adults
- 50. valve de Bauhin
- 51. PJ.Pickhardt et al NEJM 2003;349:2191-2200 PB. Cotton et al JAMA 2004;291:1713-1719 DC.Rockey et al LANCET 2005;365:305-311 CD.Johnson et al NEJM 2008;359:1207-17 (18/9/08)
- 52. 94 96 89 80 55 96 39 90 59 96 51 89 0 25 50 75 100 125 Sensitivity Specif Sensitivity Specif PICKHARDT COTTON ROCKEY POLYP > 10MM POLYP 6-10 MM %
- 53. 615 patients 5/3 mm thickness First generation 3D endoscopic software, First 2D approach. Bowel preparation as for the classic colonoscopy Inexperienced readers PB. Cotton et al JAMA 2004;291:1713-1719
- 54. 625 patients. 4 and 8 Row MDCT, 2,5 mm slice thickness. Bowel preparation 90 ml fleet phospho soda , No Tagging 2D first approach Radiologists reviewed 50 training cases, no subsequent feedback given during study DC.Rockey et al LANCET 2005;365:305-311
- 55. 1233 patients Electronic fluid cleansing and stool tagging Multi-detector CT scanners Primary 3D approach with well trained radiologist for this technique PJ.Pickhardt et al NEJM 2003;349:2191-2200
- 56. ≥10 mm ≥ 8 mm ≤ 6 mm Sensitivity VC % 93.8 93.9 88.7 Sensitivity OC % 87.5 91.5 92.3 Specificity VC % 96.0 92.2 79.6
- 57. Current indication Patient refuse optical colonoscopy Incomplete colonoscopy Obstructive colon carcinoma Anesthesia contraindication ANAES juillet 2010
- 61. The future ?
- 62. CAD = Computer Aided Diagnosis • Computer software • Assisted polyp detection • Decreases reading time • Improves sensitivity of polyp detection
- 63. Courtesy Dr. A. Dachman, Dr H. Yoshida, University of Chicago Fold (ridge) Polyp (cap) colonic wall (cup) CAD = Computer Aided Diagnosis
- 64. Courtesy Dr. A. Dachman, Dr H. Yoshida, University of Chicago
- 66. 2011 2013
- 67. 10/2002 11/ 2003 09/2005
- 69. Natural History of Small (6-9 mm) Polyps 2006 2007 20062005 Courtesy dr P. Pichkardt
- 70. Natural History of Small (6-9 mm) Polyps 20072005 2011 Courtesy dr P. Pichkardt
- 71. Polyp Size Likeliho od of Being Cancer Now Likeliho od of Being an Adenoma If Adenoma, Likelihood of Being Cancer in 10 Yr Overall Likelihood of Being Cancer in 10 Yr <5 mm <0.01% 0,3 <5% 0,01 5-9 mm <1% 0,5 5-10% 2-5% 10-15 mm 1-5% 0,8 10-15% 5-10% Natural History of Colon Polyps: Clinical Implications Y. Muto Cancer 1975; 177: 975-988
- 72. Low fiber diet Barium Laxative-free CT Colonography Ph. Lefere, S. Gryspeerdt, et al. A method to perform laxative-free CT colonography. Am J Roentgenol AJR October 2004; 183: 945-948.
- 73. VC Powerful technique Place of choice screening CRC Conclusion
Editor's Notes
- CT Colonography Cadi Medhi, Neuilly Sur Seine, France Slides, Abdominal/Kidney/Urology, Buenos Aires 2017
- Ct colonography also called virtual colonoscopy is the newly emerged imaging technique wich will be used third line (after colonoscopy and barium enema) to asses the entire colon.
- The results of such a technique depends on the quality of bowel preparation, the inflation procedure and the type of post processing techniques available.
- Bowel preparation. Patients undergo standard 24- hour liquid diet with the oral administration of 30ml of laxative solution and 20 mg of Dulcolax®. However, if renal or cardiac insuffiency we substitute Prepacol® with colopeg which is used for the classic colonoscopy bowel preparation.
- As part of their clear liquid diet , Patients also consume 500 ml of barium for solid stool tagging and 100 ml of watersoluble iodinated contrast for the opacification of luminal fluid.
- The colon is insufflated with room air to patient tolerance by an experienced technologist or radiologist. The catheter is left in the rectum, and a supine scout CT image is obtained to verify adequate bowel distention. If adequate bowel distention is present, the CT examination is performed. If adequate bowel distention is not achieved, additional air is insufflated into the rectum. After air insufflation, CT colonography is performed in a supine and prone position. Both prone and supine imaging are helpful to differentiate mobile stool from fixed pathology.
- Un topogramme est réalisé voire répété pour juger de la distension du cadre colique. 2 acquisitions l’une en decubitus l’autre en procubitus sont réalisés ceci afin de mobiliser les selles résiduelles pour les differencier des lésions coliques.duree de l’examen entre 8 et 10 mn.
- Un éxemple d’examen en temps réel realisé sur le site.
- Acquisition consists of thin collimation helical acquisition during breath hold .The CT parameters are as follows .
- Let me show you axial CT image with multiple colonic segments that are well distended, dry, and without residual fecal material. The 3D reconstruction of the colonic lumen using semi transparent rendering technique gives a “double contrast barium enema “ appearance. the colon is well-distended .
- voici un exemple de matières résiduelles correctement mélangé au produit opaque . la Gastrografine marque les selles liquides du colon droit et transverse.
- Un autre exemple ou la baryte fluide marque corrcetement les selles solides sur le coeco ascendant.
- Once the CT examination is completed, data is transfered on the workstation. The primary question is wether to begin interpretation using 2D or 3D technique. The 3D technique consists of flying through the colon and problem solving with 2D images if abnormalities are detected. The 2D technique consists of analyzing axial images with MPR and 3D images reserved for problem solving. This choice is influenced by personal preference and available workstation. In all cases quick, seamless interaction between axial,MPR and 3D endoluminal images is essential for interpretation.
- the 2D first approach : is based on review of 2D images at lung window settings; 3D views are only necessary for problem solving. Time interpretation 10-14 mn.
- exemple d’une anomalie du colon gauche : la coupe axiale en procubitus montre la lésion sur la paroi postérieure du colon transverse confirmé sur la coupe en decubitus au même endroit
- par un simple click sur la lésion suspectée les vues coronales et sagittales complètent cette étude, ceci dit il est quand même difficile de situer ce polype sur ces seules vues . sa position exacte est mieux indiquée sur le cadre colique avec un rendu 3D , la vue 3D endoscopique permet de mesurer et de definir la forme du polype : lil s’agissait d’un adénome de 8 mm du colon transverse.
- Encore un exemple de l’importance de l’interaction entre les vues axiales et coronale: Une lésion du sigmoide s’agit-t-il d’une matière non marquée ou d’un polype? c’est la vue coronale qui met en évidence le pédicule de ce polype confirmé à l’examen endoscopique.
- The first 3D approach consists of fly through evaluation. To ensure complete visualization, 2 complete flythrough evaluation are necessary, that is antegrade (from the cecum to the rectum) and retrograde (from the rectum to the cecum). mean time is 10 mn.
- Cet exemple illustre bien la nécessite de réaliser les deux modes de navigation en effet sur la navigation antérograde on ne détecte aucune anomalie alors que sur la vision rétrograde on voit un polype sessile caché derrière une haustration.
- here is an example of a polyp discovred on the antegrade fly-through, illustrated on the 2D image.
- Some additional tools are particularly helpful for 3D endoluminal navigation
- detection automatique de la ligne centrale sur un cadre colique continu sans segment collabé
- cette détection peut se faire de façon semi automatique en cas de segment colique collabé. certaines applications permettent de reconecter automatiquement les deux segments afin de ne pas interrompre la navigation.
- the Cleansing algorithm removes opacified residual luminal fluid and increases surface coverage. The cleansing procedure can be obtained on 2D and 3D images.
- this is an example : 3D endoscopic view shows a polyp located on a fold. Translucency rendering applied to 3D endoluminal image shows typical color pattern of soft tissue polyp, consisting of a red core and gradual uniform shift to green,light blue and dark blue.
- this is an other example :3D endoscopic view shows a flat polypoid lesion. Translucency applied to 3D image shows completely white interior indicative of contrast material tagging. This appearance excludes a true polyp without any use of 2D correlation. Navigation may keep going without interruption. This is an other example in real time
- on 3D endoluminal “flythrough” evaluations, small and large lesions may not be visualized because they are hidden behind folds. Not only is this a problem for 3D endoluminal imaging, it can cause similar problems at conventional colonoscopy. For these reasons other methods exists.
- Unfolded 3D cubic view , imagine you are in center of the colonic lumen with the 360° view represented as a cube with the six sides of the cube displayed at the same time.
- Virtual dissection : With this technique it is possible to display the entire inner surface of the colon with a 360° view angle .
- Virtual dissection view obtained in the supine position shows polypoid lesion , the same abnormalitie at the same level displayed on a prone position. a simple click on the suspected lesion displays automatically the 2D image at the same level and real time indicator on the colon map.
- The three characteristics that are used to determine if a polypoid lesion is residual fecal material include mobility, morphology, and internal attenuation characteristics.
- In general mobility implies residual fecal material. However it is important to realize that several segments of the colon are quite mobile and occasionally the polypoid lesion in one of these segments will appear to change position relative to the colonic surface when the patient is moved from supine to prone position and on careful inspection it is the colon that has changed position not the abnormaltie.
- A second reason why a polyp may appear mobile is if it is pedunculated and has a long stalk, in this example axial CT image obtained in the prone position shows long pedunculated polyp on the ventral surface of the sigmoid, axial ct image obtained in the supine position shows pedonculated polyp moved from ventral surface to dorsal surface of the sigmoid.
- du fait de son pédicule le polype peut changer de position entre les deux acquisitions , ici l’exemple d’un polype situé sur la face dorsale du sigmoide en decubitus dorsal et qui tombe sur la face ventrale de ce même segment sur la 2eme acquisition.
- without tagging it is difficult, if not impossible, to tell the difference between a polyp and residual fecal material retained on dorsal surface of transverse colon.
- A fecal material frequently contains areas of low or high density. Areas of low attenuation represent trapped gas , and areas of high attenuation represent high-density food particles .
- with any image study it is very difficult, if not impossible to determine the histologic nature of a neoplasm. An exception is the lipoma carefully reviewed with appropriate abdominal window settings. Lipomas are not uncommon and should not prompt endoscopic examination
- an example of pedonculated polyp.
- Flat colorectal lesions are difficult to identify at ct colonography. however carefull inspection of colonic surface shows a thickening or irregularity of a fold. this is an example.
- this is the same example showing the thickness of the fold on 3D endoscopic view and on Coronal 2D view.
- Several studies have evaluated the performance of CT colonography. Two prospective large multicenter studies, using multirow scanners are reported. These two studies have a common gold standard wich is not classic colonoscopy alone but classic colonoscopy corrected by the results of virtual colonoscopy.
- Resulats des deux études pour la détection des polypes de 10mm et compris entre 6 et 10 mm. cette discordance s’explique par le fait que .....
- In Cotton study the bowel preparation was not adapted for Ct colonography and the radiologist were not well trained for this technique.
- In this study the bowel preparation and the acquisition protocol were optimized for the technique, but fecal tagging was not used and the radiologists received no feedback during the study.
- On the other hand Pickhardt study, the bowel preparation and the acquisition protocol were optimized for this technique. also the radiologist were well trained.
- In addition, in pichardt study the sensitivity of virtual colonoscopy was superior to that of classic colonoscopy for 8 and 10 mm polyps.
- An example of occlusive distal colon carcinoma
- Ct colonography found synchronous 8 mm right colon polyp allowing the surgeon to perform polypectomy at the same time as the left colectomy and avoiding the need for classic colonoscopy .
- CAD works by color coding the colon based on shape index values the colonic wall is colored in red,the fold in orange and polyp in green.
- here is an example of polyp detected with CAD on 3D view corelated with 2D images.
- an example of pedonculated polyp , note the stool tagging .
- Surveillance d’un polype du colon droit avec une impossibilite de réaliser une polypectomie au cours de la colonoscopie .
- La determination de la position exacte du polype va aider le chirurgien a pratiquer une colotomie sous coelioscopie avec polypectomie.
- 1. Linear growth = 0.8 mm/year; Volume increase = 50%/year; Tubulovillous adenoma 2. Linear growth = 1.5 mm/year; Volume increase = 153%/year; Tubular adenoma
- The mdct and the new post processing method have made Virtual colonoscopy a very powerful technique, however a good bowel preparation as well as radiologist well trained are required to bring this technique at the first place for CCR screening.