Dr Junish Bagga

1. DNB-SS Vascular Surgery Resident, Apollo Hospital, Hyderabad
Dr. Junish S Bagga

2. • Morphologic imaging - size, irregularity of lumen, anatomic
changes in adjacent structures.
• Molecular imaging - physiological assessment, metabolic
• Vascular inflammation and infections
• Diagnosis, extent, response to therapy.

3. • Radiopharmacutical, given
intravenous, emitted radiation from
location of disease process, captured
by gamma camera and PET camera.
• Gamma camera
• Scintigraphy - 2D
• Lymph, renal, bone scan

7. SUV - Standardised uptake values, dose uptake ratio
• PET
• is very expensive
• uses positron emitting
radioisotope (tracer)
◦ 18- FDG
• gives better contrast and
spatial resolution (cf. SPECT)
• SPECT
• uses gamma emitting radioisotope
(tracer):
◦ technetium-99m
◦ iodine-123
◦ iodine-131
• gives poorer contrast and spatial
resolution (cf. PET)

8. • Atherosclerosis
• Aortic Pathology
• Vasculitis
• Vascular Graft Infection

9. • Molecular imaging of atherosclerosis - FDG uptake in carotid plaque, 31-59%
patients older than 50 years. Plaques with unstable features (large lipid core, intra
plaque hemorrhage) show more uptake than stable lesions.
• Autoradiography with labeled macrophages is more sensitive and may be used to
confirm PET findings.
• Uptake can be correlated with elevated CRP for vulnerable patients rather than
vulnerable lesions.
• Monitoring treatment, simvastatin - shows reduced fog uptake in arterial walls.
• Long term changes in FDG uptake - inflammation may be a transient feature
whereas calcifications may represent a chronic process or stable atherosclerosis.

10. • AAA - higher FDG uptake is associated with higher wall stress and correlated with
instability and macrophage infiltration. Increased FDG activity is more frequent in
small aneurysms and lesions with inflammatory changes, which are often
symptomatic and require repair.
• Dissection - FDG uptake was significantly higher in acute dissection. Higher in
patients with unfavourable outcomes than favourable outcomes.
multivariate analysis showed that the mean SUV of FDG at site of maximum
dissection can independently predict unfavourable outcome.
• FDG PET-CT may play a role in predicting prognosis of patients with type B aortic
dissection.

11. • Helpful in large to medium
vessel vasculitis due to lower
resolution. Best for aorta.
• Giant cell arteritis, takayasu
arteritis, polyarteritis nodosa,
also associated diseases like
polymyalgia rheumatica or poly
chondritis .
• Early diagnosis.
• High sensitivity with blood
markers >90%
• SUV >2.1 has >90% predictive
value.

12. • Labelled WBCs and FDG PET can be used.
• WBC scintigraphy - 80-100% sensitivity. 99-tc, 111-in. (Spect/ct)
False positive results have been reported in the presence of uptake in lymphocyte,
hematoma, thrombosis, bleeding, pseudo aneurysms. Physiologic within 1 month of
surgery. Cross labelling of RBC
• PET-CT FDG-18 - more than 95%
false positives can be due to increased activity along implants, grafts and stents, due to
chronic aseptic inflammation against foreign body by macrophages and foreign body
giant cells. Healing postoperative scars, unknown malignant disease.
• In a. Study by Keider, et al, diffuse homogenous uptake was seen in more than half of
grafts, more prevalent in Gore-tex than in Dacron grafts. No change in intensity at 16
year followup.

14. • Resolution is 4-5mm
• New probe need to be developed for newer
radiopharmaceutical agents.
• High radiation exposure - 4mSv for FDG PET CT.

16. • IVUS is a catheter based endo luminal guiding system.
• Initially developed for cardiology 1980s.
• IVUS guided interventions have similar or improved outcomes
over all - improving procedural results, reducing restenosis,
reducing need for reintervention

17. • Axial images
perpendicular to the long
axis of the catheter,
covering 360 degree
• Mechanical system
• Electronic system

19. • Choose Appropriate
catheters for best imaging.
lower frequency - more
depth.
• 45mhz - coronary
20mhz - peripheral
10mhz - aorta/ivc

20. • 2D - grey scale
• Echogenicity or echo lucency
• Calcified - highly echogenic,
posterior acoustic shadowing
• Fibrotic plaques - less brighter
than calcium, no posterior
acoustic shadowing
• Soft-lipid filled plaques - echo
Lucent, darker

21. • Similar to angiogram
created by an automated
pullback of IVUS probe
and compiling a pixel
based 2D longitudinal
reconstruction
• Pitfalls - catheter tip not
reliably at centre of lumen
• 2 pullbacks of same
vessel

22. • IVUS cannot measure flow velocity
• Provides information about interface
between vessel wall and blood stream
• Accurate volumetric measurements

23. • Color coded map of lesion
based on different
frequencies at which
various tissues reflect
ultrasound.
• Gives idea about
morphology of lesions
• CAPITAL study - accurately
diagnose fibroatheromas
>85-90% sensitivity
• Predict plaque behaviour in
response to treatment
Colour coding - dark green - fibrous, yellow/green- fibrofatty, white-
calcified, red-necrotic lipid core.

24. • Pre-procedure - Degree of stenosis, lumen
diameter, sizing of balloon, stents
• Japanese study, 5 year patency rates of fem-
pop interventions improved at 65% vs 35%
when IVUS was used
• Intra- procedure- ensure proper dilation of
stents to improve apposition to vessel walls.
40% patients had under expanded stents that
need larger balloons.
• Stent struts an be identified - echogenic

25. • Aneurysms - vessel morphology, extent of
thrombus, landing zones. Appropriate sealing of
thrombus proximally and distally.
• IVUS guided true lumen reentry - combines IVUS
with reentry technology, iliac artery, infra inguinal
chronic total occlusions
• Carotids - to identify distal ends of stenotic
lesions.

27. • Pre-op - landing zones, lengths and diameters
• Intra-op - prior to endograft delivery in patients with difficult access, IVUS can
guide rotational atherectomy or balloon angioplasty or determine if a conduit
may be necessary.
• IVUS can be helpful in detecting any sources of potentially embolic material ,
such as calcific plaques or mobile atheroma in the aortic arch.
• Post-op - assessing stent graft apposition to vessel wall to identify potential
endoleaks.

28. • Blunt traumatic aortic injury - in cases where additional imaging is required. While
repair aortic diameter may increase due to shock as compared to CTA.
• Coarctation - more sensitive than angiography for vascular wall changes,
remodelling and intimal tears.
• In infants, arch anomalies can be diagnosed by transesophageal approach using
IVUS catheters.
• Dissection - identification of true and false lumens, dynamic obstruction due to flap
motion. While treating type-B - to identify visceral vessels, branched vessels,
fenestrations. Guide wire to true/false lumen. Post op - expansion of true lumen,
extent of thrombosis in false lumen.

30. • Penetrating aortic ulcers - exact location and size of ulcer can be determined, for
landing zones.
• Intra mural hematoma - visualising arterial wall and distinguish intimate and
adventitia.
• Venous imaging - plaque morphology, trabeculae, intraluminal webs, neointimal
hyperplasia, degree of thrombosis, immobile or inverted valves.
• Venous thromboembolism - IVUS guided bedside IVC filter placement.
• Chronic cerebrospinal venous insufficiency - IVUS is superior to colour doppler and
contrast venography of IJV and azygous vein for detecting high echogenic areas
and other abnormalities therefore aiding proper sizing of stents.

31. • IVUS has higher
success rate of
identifying obstructions
due to MTS.
• Similarly in nutcracker
syndrome, IVUS is
proven more accurate
and provides precise
vessel sizing intra
operatively.

32. • Additional diagnostic information to accurately assess vascular pathology
• Cost : Benefit - increased effectiveness of treatment by preventing reintervention
• Proper stent/balloon sizing and deployment.
• In adjunct to angiography, reduces amount of contrast injected and radiation exposure,
reduced fluoroscopy time.
• Helpful in patients with contrast allergies and renal complications
• Drawback - If catheter is not in centre of lumen, distorted oblique slice may give
incorrect diameter of vessel, eg tortuous aorta.
• Pre, intra, post procedure

33. • Invasive - access related complications
• Less than 0.5% complication rate, that too while surgical
intervention rather than diagnostic
• Costly
• Low quality - noise, artifacts, 30fps (Usg - 50-750fps)
• User dependent - frequency selection, system settings - gain,
compression, gamma curves etc… to reduce noise and artifacts
• Artifacts - catheter obliquity, vessel curvature

34. • IVUS axial images, 90 to
the probe.
• Single chip forward
licking imaging system
by integrating CMUT -
capacitive micro
machined ultrasonic
transducer arrays with
front end electronics.
• NIRS + IVUS -
PROSPECT-ll trial

35. enjoy the weekend!