Ultrasound assessment of
bowel motility & vascularity
as predictors of necrotising
enterocolitis
Caron Parsons
What is NEC?
Necrosis of wall of any part
of the GI tract
Most common acquired
disorder of premature
infant
7 – 10% infants < 1500g
No change in mortality in
last 30 years
Serious long term
sequelae
Pathophysiology
Gut
immaturity
Feeding
NEC
Hypoxic
Ischaemic
Injury
Abnormal
Bacterial
Colonization
Data from NDAU
Mortality Data From NDAU
Clinical Presentation
NEC
Vomiting
Abdominal distension
PR bleeding
Temp instability
Bilious aspirates Lethargy
SEPSIS
Jaundice
Seizures
How Do We Diagnose NEC?
How do we diagnose NEC?
X-ray
Bowel wall thickening/loop separation
Pneumatosis – gas in bowel wall
Portal venous gas
Free gas
Non-specific
Necessary to repeat
X-rays ?NEC
Definitive NEC
Are there other diagnostic
methods?
Ultrasound of NEC
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Bowel wall thickening
Focal fluid collections
Pneumatosis/ Portal venous gas
Changes in Doppler signal
Bowel motility
What have other groups done?
Motility
• Definite diagnosis of NEC
• Aperistalsis
• Counted number of contractions
• 30 secs – 1 min
• No data presented on reliability of data
acquisition
• Reliability of analysis performed in one
study
• No longitudinal studies & no evaluation of
infants prior to the development of NEC
Muchantef, K., et al., Sonographic and radiographic imaging features of the neonate with
necrotizing enterocolitis: correlating findings with outcomes. Pediatr Radiol, 2013
What have other groups done?
Vascularity
• Square regions of interest
• Counted number of dots of colour Doppler
signal/cm2
• No data on reliability of data acquisition or
analysis.
Faingold, R., et al., Necrotizing enterocolitis: assessment of bowel viability with color
doppler US. Radiology, 2005. 235(2): p. 587-94.
Faingold R et al. Radiology 2005;235:587-594
©2005 by Radiological Society of North America
Faingold R et al. Radiology 2005;235:587-594
©2005 by Radiological Society of North America
Feasibility Study – Aims
• To study appearances of bowel in
healthy infants on NICU/SCBU
• To evaluate bowel motility on
ultrasound
• To evaluate reliability of acquiring and
analysing 3D power Doppler datasets
• Overall to explore possible methods
of quantification
Feasibility Study – Longer Term
Aims
• Establish normal parameters of motility
and vascularity
• Enable sample size calculation for
longitudinal study
Feasibility Study – Methodology
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Recruit 30 healthy infants (GA <40/40)
Perform single ultrasound
Motility – 2D cine loops
Vascularity – 3D volumes with Doppler
Inclusion Criteria
• All infants admitted to NICU or SCBU at
UHCW with gestation of 40+0 weeks or
less.
Exclusion Criteria
• Gestation more than 40+0 weeks
• Current diagnosis/ treatment of NEC
• Too unstable to tolerate ultrasound as
dictated by the clinical team
• Undergoing high-frequency oscillation
ventilation
• Known diagnosis of congenital bowel
disorder
• Previous bowel surgery/abdominal wall
defect
Recruitment
15
Approached
13
Yes
4
Discharged
2
No
9
Scanned
Break
There was a change to the protocol during
recruitment
Therefore
Evaluate the protocol and set-up of the
study
Start evaluating the image analysis
methodology
Motility – Original Methodology
• Acquire cine-loops in a four quadrant
approach
• Two observers
• Analyse as per previous groups
• Presence/absence of contractions
• Number of contractions/minute
• Computerised vectorial analysis - ShIRT
Motility Methodology
This part of the study did not change
2D cine loops (10 secs)
Evaluation
Basic
ShIRT – by colleagues in Sheffield
2D Cine-Loop
Initial ShIRT Evaluation
Vascularity – Original Methodology
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Acquire 3D power Doppler volumes
2 observers
2 sets of data per observer
Off-line analysis in VOCAL software
Select ROI
Software calculates vascularity indices
Vascularity – Changes To
Methodology
 Suggestion of 2D acquisition over time rather than 3D
volume
 This was then trialed on the latter 6 of the recruited patients
 Availability of proprietary software for 2D Doppler data
 However…..
 Issues with proprietary software
 Cost
 Understanding of physics/ mathematics behind calculations
 Difficulty with obtaining trial versions
2D Doppler Cine-Loop
Baby with NEC
Initial Evaluation with Q-Flow
Vascularity – Where next?
We designed our own.
Using MatLab software and a very clever
physicist
Data Analysis
The idea is to use random ROI placement
within the Power Doppler data clips to sample
the bowel and calculate a global measure of
vascularity for each subject
Two measures
%Colour – proportion of colour pixels to
grey-scale pixels in ROI
Luminance – intensity of each colour pixel
 Summated for ROI
MatLab Software
Luminance: Total v Sampled
Why sample?
In the future we will be acquiring repeated
samples on a daily basis
Bowel is mobile
The width of the Doppler box cannot be
standardised
What Next?
Motility – Waiting for results from Sheffield
Vascularity
Statistician looking at random circle ROI
data
Intraclass correlations for reliability of
Data acquisition
Data analysis
Design software for 3D Doppler volumes
Next stage of feasibility study
Pre and post feeding in healthy
premature infants
Summary
• NEC is difficult to diagnose in the early
stages
• The role of ultrasound is increasing in
NEC
• Motility and vascularity have postulated
roles in the pathophysiology of NEC
• There is potential to characterize motility
and measure vascularity with novel
software
Study Group
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Dr. E. Helm, Consultant Radiologist, UHCW
Prof. C. Hutchinson, Prof of Imaging,
University of Warwick
Dr. V. Sherwood, Clinical Scientist, UHCW
Dr. P. Satodia, Consultant Neonatologist,
UHCW
Dr. R. DeBoer, Consultant Neonatologist,
UHCW
Dr. H.Parsons, Research Fellow in Statistics,
University of Warwick
Dr. J. Fenner, Medical Physics Group,
University of Sheffield