3D vascular ultrasound for AAA; by Kim Bredahl.
Kim Bredahl
3D Vascular US
2D approach - do in both planes A P and longitudinal
Poor agreemenet of more than 5 mm between operators is well described
most likely reason is wrong image plane
US reasons
1) calliper palement
2) plane
3) don’t get the lateral measure
4) cardiac phase
Biplane imaging mentioned: being able to see both views on the same screen image
Caval vein, vertebrae etc can be used as landmark registration
To compensate for some of these limitation: usng a centreline approach
Agreement with interobserver variation: 1.9 to 1.6 mm SD so no real change
But in terms of variation from the CTA measurement: Better result, from a 5 mm difference between modalities down to a 2 mm difference
The centreline application inthe philips machine is now fully automatic
when using CT volume as gold standard, the volume approach by US correlates the best
But the volume approach can only be achieved in full in only 46% of patients
By stitching together multiple acquisitions Kim managed to get the full volume scanning % up to 69%
Thrombus is a source of proteolytic enzymes degrading the aortic wall
What to do next : more sensitive tooks, AI, measure hidden growth, measure shape.
EVAR surveillance 'paradox', by George Antoniou.
George Antoniou
EVAR surveillance paradox
Manchester
EVAR is mainstay of rx for AAA
Long term RCT data states increased risk of reintervention, rutpure and aneuyrsm related mortality
Imaging intended to look at: Endoleak, migration, stent fracture, sac rupture.
O: to compar survival of pts who were EVAR surveillance compliant, compared to those who were not.
systematic search
Identified 13 studies
22,762 patients ; about half compliant
Most of the studies were in the USA. Almost all were retrospective studies.
Rx period range 1996 - 2020
Pooled all cause mortality
0.61 - 1.77 CI and diamond at 1.04 forest plot for all
p value 0.88
Pooled on aneurysm related mortality
no stats sig diff
p=0.12
non compliant pts had lower risk of rupture compared to those compliant at the margin of stats significant at p=0.05
GRADE = certainty of outcomes was very low for all papers
and all were observational papers
INTERPRETATION
complete EVAR surveillance does not prolong life expectancy
or
complete surveillance has positive outcome benefit but only in a subset of pts with specific characeristics
now doing a delphi study to come up with a risk-informed surveillance strategy
Q: was surveillance more important during the earlier yesars of the life cycle of EVAR?
A: did not really answer the qn initially. Then accepted merit on fu qn.
Co-DETECT study on Covid era AAA duplexes, by Kamran Modaresi.
Study relates to the 1st wave of COVID
26 March 2020 to 25 March 2021
Question: How do we decide which AAA patient is ‘urgent’?
Intresting info on the Northwick partk surveillance protocol
Males at over 45 mm are scanned 6 monthly, women too
but men referred at 53mm and women at 48 mm to vascular.
Post ops during 1st wave:
80 were highlighted as urgent (awaiting first post op scan, known type 2s, something else)
Hardly any would come in
Surveillance group
Considered urgent?
130
Only 39 wnted to come in
17 deaths; one rupture death in these (although 5 deaths had moved out of area so cause not known)
“Are we scanning too much?”
Q: does scanning people who are already at threshold but dithering offer false reassurance?
Answer was unfortunately a complete non sequiter