Enterography : A New Paradigm in Small Bowel Imaging

Transcription

1 Massachusetts General Hospital Harvard Medical School CT Enterography : A New Paradigm in Small Bowel Imaging Dushyant Sahani, M.D Director of CT Associate Professor Department of Radiology Massachusetts General Hospital Harvard Medical School

2 Small Bowel Evaluation Techniques Conventional techniques SBFT, Enteroclysis

3 Small Bowel Evaluation Techniques Conventional techniques SBFT, Enteroclysis and Endoscopy Newer techniques Capsule Endoscopy

4 Capsule Endoscopy

5 In the last decade, with significant advances in technology there has been a paradigm shift in imaging evaluation of gastro-intestinal tract (GIT) SIGNIFICANCE ADVANCES IN GASTROINTESTINAL IMAGING Success has become attainable & practical due to advent if of multidetector CT (MDCT) with administration of oral contrast media (OCM) MDCT -High resolution -Isotropic images -Volume rendering -Multiple planes OCM -Adequate distention -Luminal, mural & extra-luminal evaluation - Seeing through the bowel loops

6 CONTRAST MEDIA / AGENTS POSITIVE / WHITE (POCM) Barium Iodine NEGATIVE / BLACK Air Fat NEUTRAL / GRAY (NOCM) Water / Milk / Juice Low density barium (VoLumen) Polyethylene glycol (PGE) Lactulose Simethicone coated cellulose Locust bean gum - mannitol commercial availability in U.S.A. for CT? Targeted use of OCM allows optimal evaluation of pathology.

7 EFFECT ON MOTILITY & Normal Collapsed Bowel DISTENTION Water soluble - Iodinated VoLumen Distention Click to view Click to view Click to view Water Barium 2% Symbolic Motility Waveform Click to view Click to view Motility increased due to larger volume consumed rapidly & sorbitol content (osmotic) Adequate distention is important for detection of pathology. Effect on motility needs to be considered for optimizing the time to scan.

8 CT Oral Contrast Iodine Agents Positive Contrast Agents Diluted Iodinated/barium 2-5% Used in CT because of experience with GI studies Benefits Unequivocal identification of bowel loop if opacified Extravasation identification Barium

9 Oral Contrast Agents (OCA) Positive OCA Rely on structural changes in the bowel Pseudolesions due to poor mixing May mask subtle pathology in the wall Neutral OCA Better assessment of the enhancing bowel wall Do not interfere with 3D volume sets

10 TI Crohn s Positive Oral Contrast

11 Barium VoLumen

12 GRAFT VERSUS HOST DISEASE OCM - PEARLS STRICTURES POCM NOCM Graft versus host disease the abnormal enhancing mucosa and extent of involvement is better appreciated with use of NOCM Multiple small bowel strictures with mucosal & mural enhancement suggesting active CD

13 Small Bowel Lesions: Positive Vs. Neutral CM CT CT

14 NEUTRAL (GRAY) OCM WATER - PROTOCOLS UPPER ABDOMEN SCAN <30 min 1 glass = 450 ml min On scanner table ABDOMEN & PELVIS min min On scanner table SCAN <40

15 NEUTRAL (GRAY) OCM WATER Allows assessment of luminal pathology & bowel wall Excellent for upper GIT if scanned at appropriate time GIST Adequately distended 2 nd part of duodenum with visible mural details (small arrows) Ampullary mass lesion invading the duodenum Large gastrointestinal stromal tumor (GIST) with mass effect on stomach NOCM High quality curved reformats of the pancreas due to neutral background POCM

16 NEUTRAL (GRAY) OCM WATER - PERILS Transits rapidly, absorbed distally, preventing adequate distention Suboptimal distention obscures, masks or mimics pathology Duodenum COLLAPSED SEGMENTS Sub-optimal distention of segments of small bowel Rapid transit of water and inappropriate scan delay resulting in collapsed duodenum which cannot be separated from pancreas

17 Neutral CT OCA PEG Methylcellulose Lactulose AJR 2005; 185:1173 MR Enterography Essen, Germany Locust bean gum + Mannitol Gd-DTPA enhancement Commercially NOT available in US

18 Neutral CT Oral Contrast Agents VoLumen (E-Z-EM Product) Gum system, Sorbitol & Barium (0.1%w/v) HU Water = < 10 HU Berry taste Weak grape Kool-aid

19 Advantages of Viscous Neutral OCM Better bowel distension Superior lumen to wall differentiation compared to positive contrasts Better detection of mucosal and mural pathologies Improved quality of post processed 3D images

20 NEUTRAL OCM LDB (VoLumen) PROTOCOLS CT ENTEROGRAPHY 1 Bottle = 450 ml SCAN 1 glass = 450 ml 0-20 min min min MIN On scanner table COLONIC INDICATIONS SCAN 0-20 min min min >60 MIN

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22 CTE: Technique Focused exam on small bowel Intestines distention with a fairly large amount of intraluminal contrast material IV Contrast for lesions detection and to assess disease activity. Visualization: axial+ MPR/3D

23 IBD: minutes delay

24 CT Enterography Oral Contrast Protocols NYU MGH Cleveland Clinic Mayo Clinic 1350 ml total 1350 total 1350 ml total 1350 ml total min min min min min min min min 225 H 2 O 5 min 225 H 2 O 5 min min min 225 H 2 O scanner 225 H 2 O scanner min min 0.1 mg Glucagon Reglan prn

25 CT Enterography: Technique Uni-phasic scans start sec Iodinated CM: cc of cc/sec Dual-phase study GI bleed slice scanner DC: mm Reconstruct 3-5 mm axial Retro-recon:1.25/0.625mm 3-5 mm coronal MIPs

26 CTE: Established Indications *Suspected or Known Crohn s *Colitis Assess small bowel for Crohn s GI Bleeding/Luminal Mass DX

27 Role of Imaging in IBD Initial disease evaluation Treatment response Assessment for acute exacerbation Detection of stricture and bowel obstruction Extraintestinal complications (abscess, fistula, LAD, PSC)

28 CTE CTE

29 Crohn s disease multifocal strictures

30 CT Enterography Small Bowel Findings positive for Crohn s Disease (Hara et al. Radiology 2006) Study of 17 pts SBFT Ileoscopy CT enterography Capsule Endoscopy 17 % 65 % 53 % 71 % CTE depicted > 2x Crohn disease than did SBFT CTE benefit: Extra-luminal findings and complications

31 IBD Complications Abscess Fistula Liver Abscess

32 CTE: IBD Disease Activity Bodily et al. Radiology 2006; 238:505 N = 96 patients Ileoscopy vs. CTE Quantitative vs. qualitative CTE Quantitative mural attenuation (enhancement) TI correlate well with ileoscopic & histologic findings of inflammation (Crohn s) Threshold of 109 HU Active Chronic

33 GI Bleed

34 CT Enterography: Emerging Indications Abdominal pain Diarrhea Malabsorption Small bowel tumors/polyps Eventually will replace almost all DX barium work in small bowel PET CT

35 GVHD

36 Small Bowel Polyp

37 Jejunal GIST

38 CT Enterography : Issues Learning Curve Familiarity with CTE critical to limit Pseudodisease detection Detection of extraluminal findings/collections/leaks Radiation Dose Patient acceptance Increased bowel activity

39 NEUTRAL OCM VOLUMEN - PERILS DIFFICULTY WITH ISO-ATTENUATING EXTRA-LUMINAL LESIONS NOCM POCM NOCM POCM Extraluminal collection suspected on CTE, however is more conspicuous with positive OCM Early peritoneal implants less visible with NOCM but more obvious on the follow up exam with POCM OCCASIONAL DISCOMFORT DUE TO DISTENTION & INCREASED MOTILITY

40 Extraluminal Collection NOCM POCM

41 Enteric Fistula

42 Recent attention focused on radiation risk to patients from diagnostic imaging Rise in medical imaging utilization (60 million CT exams annually) Risk estimates extrapolated from atomic bomb/nuclear fallout survivors BEIR VII supports LNT model Ionizing radiation classified by HHS as carcinogen in 2005 Risk Brenner et al. NEJM 2007 Dose

43 Children particularly vulnerable to ionizing radiation Increased cell division/tissue growth Longer life expectancy/latency period Lower cross-sectional area increases absorbed dose One study estimates 1 in 1000 children undergoing CT will die of radiation-induced malignancy Brenner DJ et al, Am J Roentgenol (2001)

44 Potential radiation risk to children Minimum exposure required for inc risk ranges from msv Exam Mean dose to children (msv) Natural bkgd 2-4 CXR 0.02 Fluoro exam CT (Abd/Pel) 5 PET 15 PET-CT Rice HE et al, J Ped Surg (2007)

45 Low Dose CT exams Original CT scan NOISE SIMULATION SOFTWARE (GE HEALTHCARE) 150 Simulated CT Studies NI 18 NI 20 NI 25 NI 30 NI 35 Kambadakone et al. RSNA 2008

46 Radiation Dose Benefits NI-15 NI-35 Original CT data 3-15m Sv Estimated Reduction NI % NI % NI % NI % NI % Kambadakone et al. RSNA 2008

47 Jan Radiation Dose 11.6mSv Dec Radiation Dose 5.1 msv 23 yrs old with Crohn s Disease. Baseline and FU CT exam Axial & Coronal CT images demonstrating wall thickening and enhancement (red arrow) and increased perienteric vascularity (white arrow) 40% ASIR 55% Dose Reduction

48 Coronal CT Image demonstrating wall thickening and mucosal Enhancement (red arrow) Axial CT Image demonstrating wall thickening and mucosal enhancement (red arrow) and increased perienteric vascularity (white arrow) 19 yrs old with Crohn s Disease. First CT exam 40% ASIR Coronal CT Image demonstrating a lymph node (yellow arrow) and increased perienteric vascularity (white arrow) RADIATION DOSE msv

49 Potential of MRI for evaluating IBD No ionizing radiation Superior soft tissue resolution compared with CT In routine clinical use for detecting perianal fistulae

50 IBD protocol MRI Technique Oral prep same as with CT given 45 mins prior Coronal T2WI screen Targeted axial T2W-FS 0.1mmol/kg wt. Coronal T1 FS pre- and 1, 3, 5 mins post Quantitative T1 maps to assess enhancement Hi-res axial T1 FS post-gado images

51 18F with known Crohn s SBFT shows narrowing of TI T2 shows segmental narrowing, wall thickening, fatty proliferation at same location

52 Progressive mucosal enhancement suggestive of active inflammation PRE 1 MIN POST 5 MIN POST

53 Summary Advances in MDCT and oral contrast has renewed interest in small bowel imaging with CT CTE using neutral oral contrast most promising non-invasive test Sensitive for the evaluation of luminal and extra luminal findings in IBD Disease activity Role evolving for other indication in small bowel

54 Summary Oral contrast protocol optimization is essential for the best results MPR s/3d are complimentary to axial data set and its routine use is encouraged Patient education for AE s Bowel motion Anticipate a short learning curve Use of MRVR s can minimize pitfalls

55 MRI Summary Evaluation of patients with IBD disease in young patients Monitoring disease activity Complications/Fistula

56 GIT Imaging: New Paradigm

57 Acknowledgment Mark Baker MD Cleveland Clinic Michael Gee MD MGH