Download IMPORTANCE OF ORAL CONTRAST IN CT IMAGING

IMPORTANCE OF ORAL CONTRAST IN
CT IMAGING
Ania Z. Kielar1,2,
1. Department Of Medical Imaging, The Ottawa Hospital, Ottawa, ON.
2. Ottawa Hospital Research Institute, University Of Ottawa, Ottawa, ON.
www.ottawahospital.on.ca | Affiliated with • Affilié à
DISCLOSURES
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None of the authors have any disclosures related to this presentation
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OUTLINE
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Step by step arguments proving utility of enteric contrast
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DR. PATLAS…
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Your previous arguments supporting cutting corners…. Are full of
ORAL CONTRAST!!
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#1: WE ARE RADIOLOGISTS
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Radiologists play an important role, in helping diagnose and guide
management in cases of acute abdominal conditions in ED patients
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Future management decisions rest on our diagnosis
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No point in imaging if we can’t make the correct diagnosis
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It is often not the diagnosis suggested in the history
•  “Abdominal pain”: could be a tumour, Crohn’s etc.
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APPENDICITIS
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Before the use of CT, surgeons accepted a false-positive rate (or negative
appendectomy rate) of 20% to avoid missing cases of appendicitis.
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Negative appendectomy rate among patients with preoperative CT is much
lower, in the range of 3%–6%
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In the reported imaging studies, only 40% of imaged subjects on average
had appendicitis and, in approximately 30% of subjects, another cause
for RLQ pain was identified by imaging
Applegate et al Raidology 2001
Bendeck et al Radiology 2002
Chooi et al CARJ 2007
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BACKGROUND:
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Increasing focus in radiology literature on latent errors
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Patient experience from time of request to time
physician acts on, is the result of many individual
steps
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It is our responsibility to close up these latent holes
Lee CS et al. AJR 2013;201(3)
Reason,J Human Error: models and management. BMJ. 2000;320(7237)
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EXAMPLES OF STEPS INVOLVED IN CT SCAN FROM ED
Technologist study quality (mAs, kVp)
Communication of accurate
Radiologist chooses protocol
results to physician
Requisition communication
Decisions related
to patient care
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BACKGROUND SUPPORTING EVIDENCE
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Internal study looking at effect of history on CT accuracy for abdominal/
pelvic CT in the ER. 350 consecutive patients for abdominal CT.
•  9% of CT findings were unexpected based on history provided
Stefanski et al. TOH data (submitted for publication)
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RESULTS
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52/350 (15.1%) missing information that may have potentially impacted
either the imaging protocol chosen or the final diagnosis
Stefanski et al. TOH data (submitted for publication)
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RESULTS
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95/350 (27%) patients had complex histories related to the abdomen
•  Complex = history of thoraco-abdominal malignancy, colectomy, chronic liver
disease, chronic pancreatitis, etc.
Stefanski et al. TOH data (submitted for publication)
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▶ You
might find this hard to swallow……
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EUROPEAN RADIOLOGY 2015
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KEY POINTS
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Positive enteric contrast should be used in selected questions (fistula,
leaks, abscesses)
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Neutral oral contrast ensures equivalent delineation of the bowel
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Diagnostic reliability are impaired without enteric contrast
Kammerer AJ et al. European Radiology 2015;25:669
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#2: RADIATION DOSE HIGHER WITH ORAL CONTRAST?
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New machines are very low dose compared to previous
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Minuscule increased dose won’t make a difference
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Next generations even better
•  Iterative reconstruction
•  Filtered back projection
Patino M.et al AJR 2015;204(2):W176-83
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OBJECTIVE:
A QUANTITATIVE
COMPARISON OF
NOISE REDUCTION
ACROSS FIVE
COMMERCIAL
(HYBRID AND MODELBASED) ITERATIVE
RECONSTRUCTION
TECHNIQUES: AN
ANTHROPOMORPHIC
PHANTOM STUDY
Pa#no M et al AJR 2015;204(2):W176-­‐83 Compare performance of 3 hybrid iterative reconstruction techniques (ASiR,
iDose4, SAFIRE) and their image noise reduction on low-dose CT examinations
using filtered back projection (FBP) as the standard reference.
MATERIALS AND METHODS.
An abdomen phantom was scanned at 100 and 120 kVp and different tube
current-exposure time products (25-100 mAs) on 3 CT systems (for ASiR and Veo,
Discovery CT750 HD; for iDose4 and IMR, Brilliance iCT; and for SAFIRE,
Somatom Definition Flash). Volume CT dose index and dose-length product, was
compared.
RESULTS. No significant differences in radiation dose and image noise among
the scanners when FBP was used (p > 0.05).
Gradual image noise reduction was observed with each increasing increment of
hybrid IRT strength, with a maximum noise suppression of 50% . Similar noise
reduction was achieved on the scanners by applying specific hybrid IRT strengths.
Maximum noise reduction was higher on model-based IRTs (68.3-81.1%) than
hybrid IRTs (48.2-53.9%) (p < 0.05).
CONCLUSION. When constant scanning parameters are used, radiation dose &
image noise on FBP are similar for CT scanners made by different manufacturers.
Significant image noise reduction is achieved on low-dose CT examinations
rendered with IRTs.
RADIATION DOSE ISSUES CONTINUED
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We agree that radiation exposure at older age likely has less
consequences
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Why wouldn’t we do our best to diagnose findings in these patients?
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ALARA (as Reasonably possible)
•  Ties into last argument
Dr. Patlas
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IMAGING OF ELDERLY PATIENTS
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In our province, 800 000 patients without a family doctor
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Multiple medical problems: more complicated
•  As radiologists, we need to image them properly to get a full picture
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(27% of patients in our study of ALL COMERS had complex histories)
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EXAMPLE
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86 year old with abdominal pain and peritonitic signs
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FINAL DIAGNOSIS
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Free air seen
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Cause not diagnosed
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Perforated duodenal ulcer
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Oral contrast may have helped
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YOUNG PATIENTS
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Often thinner with less intra-abdominal fat separating structures
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We DO care about radiation: Image Wisely & Image Gently
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Use ultrasound first….
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It IS wise to image once, in one phase… get all info you can
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Oral contrast in the lumen of the appendix essentially excludes appendicitis
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Missing early appendicitis can have severe consequences
•  Abscess, longer hospital stay, potential for infertility
Drake FT et al Improvement in the diagnosis of appendicitis Adv Surg 2013;47:299
Ganguli S et al. RLQ pain: value of non-visualized appendix in CT. Radiology
2006;241(1):175
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ALL PATIENTS
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ER busy place
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Pressures to get patients through
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Often history and physical limited
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In some centers, triage nurse/physician assistant requests imaging
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Actual diagnosis frequently not what was initially expected
•  We need to take an active role in make a diagnosis in these varied patients
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#4: DELAY OF DIAGNOSIS?
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Lets work as a team with the ED
•  If oral contrast available at nursing stations, as soon as CT
request is made (often before patient seen by ER physician),
time delay minimal
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Positive oral contrast agents mixed with lactulose can
speed transit through the small bowel (30-60 min)
Algin O et al. A novel biphasic oral contrast solution for enterographic
studies. JCAT 2013;37(1):65-74
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COUNTER ARGUMENT MADE BY DR. PATLAS
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▶ Alabousi
CARJ 2015 NOV;66(4):
318-22.
IS ORAL CONTRAST N
ECESSARY FOR
MULTI-DETECTOR
COMPUTED
TOMOGRAPHY
IMAGING OF PATIENTS
WITH
ACUTE ABDOMINAL
PAIN?
A1, Patlas MN2, Sne N3, Katz DS4.
▶ Conducted a retrospective study to assess the effect of
discontinuing oral contrast use for MDCT scans of the abdomen & pelvis for patients
presenting with acute abdominal pain and body Patients with BMI <25 continued to
receive oral contrast. mass index (BMI) >25. The medical records were reviewed to
determine the rate of repeat imaging within 7 days from the initial CT scan, as well as
delayed or missed diagnoses related to the absence of oral contrast. The study was
approved by the research ethics board at our institution.
▶ RESULTS:
▶ A total of 1378 patients had an MDCT examination of the abdomen and pelvis
between November 1, 2012, and October 31, 2013. 375 patients met the inclusion
criteria (174 males and 201 females; mean age 57 years; range 18-97 years). Seven
of 375 (1.9%) patients had a repeat CT examination with oral contrast within 7
days. Of these 7 patients, none had a change in the course of their management due
to the utilization of oral contrast. No delayed or missed diagnoses related to the
absence of oral contrast were identified.
▶ CONCLUSION:
▶ Omitting oral contrast for imaging patients with BMI >25 presenting with
acute abdominal pain resulted in no delayed or missed diagnoses, in our retrospective
study. The benefits of prompt imaging diagnosis outweigh the unlikely need for repeat
imaging.
#5 YOU HAVE NOT SEEN THE PATIENT!!!
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How can you decide if they have < or > 25 BMI?
•  We still have skinny people in Canada…..
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Once they arrive in radiology, those with < 25 BMI will end up with more
delay than if everyone given oral contrast at the initial nursing station
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Often not told of other pertinent history
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#6 INCREASED LITIGATION?
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This is not a huge concern
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We still need to do everything possible to get the diagnosis correct
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Study by Weir et al, 2012. On first reporting, CT misses 18% of diagnoses
that ultimately require operative intervention!!
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It is not what the patient can do for you, but what YOU can do for the
patient….
•  Lets improve accurate, be more confident, not miss abscesses, peritoneal
metastases & other unexpected findings
Weir J. Use of pre-operateive CT in assessment of acute
abdomen. Ann R Coll Surg Engl 2012;94(2)
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#7 PATIENTS PRESENTING POST OP
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Leaks
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Obstructions
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Possible abscess
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No arguments here???? I can’t think of any
•  Lets agree to agree Dr. Patlas
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NEED TO WAIT FOR CONTRAST TO ARRIVE
a
b
Perihepatic gas
Perihepatic contrast
Oral
Anastomosis
Further
extraluminal
contrast
Example case: Post ileocolonic anastomosis. (a) Intraluminal contrast has not reached the
anastomosis (b) intraluminal contrast has reached the anastomosis and leakage is clearly evident
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EXAMPLES
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A. 95 year old with right sided pain
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Was an appendicitis… rare in 95 year old
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Redundant colon, cecal bascule
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Very long appendix…. Initially unclear diagnosis
•  (Meckel’s vs small bowel loop)
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COUNTER ARGUMENT: BOWEL OBSTRUCTION
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Administration of oral contrast proves high grade vs non
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Patients vomiting anyway (gastric juices continue to be made and saliva
swallowed)
•  12.9% in two groups: one with and other without oral contrast
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They are often dehydrated in the ER already… give them some oral contrast
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Minimal literature about risk of complications from oral contrast in patients who
subsequently have to go to the OR
•  Peritoneal cavity undergoes lavage in case of perforation (you are just speeding up the
diagnosis of perforation and reducing time for infection to develop)
Renae E et al. Arch Surg 1999;134(6):662
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CONCLUSION
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We need to make the most accurate diagnosis possible
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We don’t know the patient’s full history and often elderly patients have
more complex medical issues
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Younger patients are typically thinner and therefore hard to assess
without oral contrast
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Consequences of missing early appendicitis, abscesses, leaks and
bleeding
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Lets be efficient and accurate, working with the ER workflow to improve
patient care
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CONCLUSION
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GIVE YOUR PATIENTS ORAL CONTRAST
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If you don’t use (oral contrast), you loose
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