4/16/2016 Non-Invasive Assessment of Neuroischemic Limb, Minimally - - PowerPoint PPT Presentation

4/16/2016 1

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Non-Invasive Assessment of Neuroischemic Limb, What’s New

Venita Chandra, MD Clinical Assistant Professor of Surgery Division of Vascular Surgery Stanford Medical School, Stanford, CA

UCSF Vascular Symposium April 16th, 2016

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Minimally-Invasive Assessment of Neuroischemic Limb, What’s New

Venita Chandra, MD Clinical Assistant Professor of Surgery Division of Vascular Surgery Stanford Medical School, Stanford, CA

UCSF Vascular Symposium April 16th, 2016

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• I have no relevant disclosures

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What’s new…ish?

• Indocyanine Green

Angiography (ICGA)

• Hyperspectral imaging (HSI)
• SPECT/PET
• Microoxygen sensors (MOXY)

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Indocyanine Green Angiography (ICGA)

Desai N. JTCS. 132(3): 2006.

Peak

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• Significant differences in

perfusion rates in patients with severe or moderate PAOD compared to normal controls.

• More sensitive that

conventional ABI to detect mild functional impairment

• Significant differences in

perfusion rates in patients with severe or moderate PAOD compared to normal controls.

• More sensitive that

conventional ABI to detect mild functional impairment STANFORD

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ICGA after intervention

Colvard et. al. SPY Technology as an Adjunctive Measure for Lower Extremity Perfusion JVS, In Print.

Several patients without significant changes in ABI, but changes in ICGA values Several patients without significant changes in ABI, but changes in ICGA values

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ICGA

• Pros:
• Quantitative and Qualitative

data

• Topographic data across the

region of interest

• Appears to be able to assess

changes in perfusion

• Cons:
• Contraindicated in liver and

kidney failure

• Requires IV access
• Added time
• Clinical impact unknown

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Hyperspectral Imaging (HSI)

• Scanning spectroscopy to construct

a spatial anatomic map for tissue

• xygenation using visual light
• Map generated by local molecular

composition of oxyhemoglobin and deoxyhemoglobin levels based on wavelength selection

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HSI for PAD

• 65 PAD limbs vs. 92 non-PAD limbs
• Significant difference in

deoxyhemoglobin levels

• Significant differences between

monophasic, biphasic and triphasic waveforms

Chin et. al. JVS 2011

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• HSI shown to identify skin

microcirculation in the neuroischemic limb

• High sensitivity (86%) and

specificity (88%) in determining healing potential

• HSI shown to identify skin

microcirculation in the neuroischemic limb

• High sensitivity (86%) and

specificity (88%) in determining healing potential

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HSI

• Pros:
• Noninvasive,
• Delivers finer assessment of

perfusion by evaluation of

• xy and deoxyhemoglobin

levels

• Cons:
• Vulnerable to same

weaknesses in terms of skin temperature/condition as TCO2 and/or SPP

• No well organized/planned

prospective studies

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SPECT/PET

• Radioisotopes + nuclear imaging +

high-resolution CT scan imaging

• Can visualize perfusion and process
• f angiogenesis
• Get both functional and structural

information

Stacy MR,ZhouW,SinusasAJ.Radiotracerimagingof peripheral vasculardisease.JNuclMed2013;54:2104–10. Hybrid 99mTc-tetrofosmin single photon emission tomography (SPECT)/CT

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Angiogenesis

Adah Almutairi et al. PNAS 2009;106:685-690 Increased activity in ischemic limb

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SPECT/CT

• Pros:
• Noninvasive
• Can give a lot if

specific/targeted information (i.e infection, angiogenesis)

• Cons:
• Expensive
• Require trained team of

nuclear technicians

• Time
• Full potential of clinical

applications unknown

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Microoxygen Sensors (Lumee *)

• Injectable, oxygen-sensitive micro

sensor (0.5x0.5x0.5mm)

• Biocompatible hydrogel + NIR
• xygen-sensitive molecule
• External light emitting diode

detector

• Pulses of light excite microsensor

and sends light signal back

* Profusa Inc. South San Francisco STANFORD

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• First in man safety

and feasibility study in CLI patients undergoing endovascular intervention

• Statistically

significant increase in O2 concentration after intervention

• First in man safety

and feasibility study in CLI patients undergoing endovascular intervention

• Statistically

significant increase in O2 concentration after intervention STANFORD

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Microoxygen Sensors

• Pros
• Live understanding of tissue

perfusion/oxygenation

• Appears to be more reliable

than other methods such as TcPo2 and pulse oximetry

• Cons
• Not FDA approved
• Permanent implant

(although well tolerated)

• Very little clinical evidence
• Invasive

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Conclusions

• True understanding of tissue perfusion, key in management of

the neuroischemic limb

• Many new and exciting for the assessment of the neuroischemic

limb

• Most need further study to best determine their clinical impact

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Thank You!

vascular.stanford.edu