Non-contrast ultrasound assessment of blood flow in clinical practice

Emmanuel Abiola Babington; Cletus Amedu; Ebuka Anyasor; Ruth Reeve

doi:10.15557/jou.2024.0029

Figures & Tables

Waveforms of arterial blood (A) flow towards the transducer, and venous blood (B) flow away from the transducer. The waveforms illustrate a higher frequency (4 cycles per second) of the arterial flow (a positive shift) than the venous flow frequency (2 cycles per second) within the same period. This is further illustrated (C, D) using metal spring diagrams where there are more compressions on the spring pattern representing flow towards the transducer and more regions of rarefactions on the spring pattern representing flow away from the transducer

Sonograms of the right internal (ICA) and common carotid arteries (CCA) showing spectral Doppler waveforms and measurements of the PSV and EDV within the lumen of the vessels – images by E.A.

A simple chart showing the various Doppler modalities with their corresponding velocity ranges. CDI and PDI have filtered out clutter artefacts within similar velocities as microvascular velocity flow signals. McVI can separate the clutter from microvascular flows

A 7 mm polyp in the gallbladder of a 42-year-old male. Color Doppler with a low PRF setting revealed no vascularity evidence. Microvascular imaging revealed a feeder vessel from the gallbladder wall into the polyp. Dual-display B-mode-B-flow ultrasound also revealed subtle evidence of the feeder vessel (adjacent to the caliper) – images by E.B.

Abnormally thickened endometrium (18.6 mm anteroposteriorly) in a 12-year-old female with symptoms of abnormal uterine bleeding. PDI and CDI showed some myometrial vessels with no significant flow evidence in the endometrium. B-flow showed the myometrial vessels with tiny vessels within the endometrium. McVI revealed evidence of endometrial hypervascularity that was not evident on CDI/PDI – images by E.B.

Summary of various non-contrast ultrasound flow modes_ Microvascular imaging (McVI) nomenclatures used by different ultrasound manufacturers (listed alphabetically)

Company	Canon Medical Systems	General Electric Healthcare	Hitachi Medical Systems	Philips Healthcare	Samsung Medison	Siemens Healthineers
Brand name	Superb Microvascular Imaging	MicroVascular Imaging	eFlow	MicroFlow Imaging	MicroVascular Flow	Slow Flow
Acronym	SMI	MVI	–	MFI	MV Flow	-

Summary of various non-contrast ultrasound flow modes

Flow mode	CDI	PDI	ADF	McVI	B-flow
Working principle	Doppler	Doppler	Doppler	Doppler	Non-Doppler
Generation	1st Gen.	2nd Gen.	3rd Gen.	3rd Gen.	3rd Gen.
Major pros	1. Adjustable Doppler box 2. Provides flow directionality information 3. Available on all ultrasound machines and probes 4. Better penetration than MVI and B-flow	1. More sensitive than CDI 2. Adjustable Doppler box 3. Available on all ultrasound machines and probes 4. Better penetration than MVI and B-flow	1. Suitable for examining the fetal placental vessels and fetal heart chambers 2. Shows flow directionality	1. The most sensitive (non-contrast) flow mode to microvascularity 2. Can prevent the need for other invasive or radiation examinations	1. Not angle-dependent 2. Sensitive to slow flows 3. Can visualize tiny vessels 4. Provides flow information of the entire ultrasound screen; no Doppler box is required
Major cons	1. Filters out microvascularity 2. Angle dependent 3. Prone to aliasing	1. Filters out microvascularity 2. Focuses more on flow intensity over velocity	1. Least sensitive to microvascularity 2. Provided by only one manufacturer	1. Doppler box is limited in size. 2. Only available on high-end ultrasound machines 3. Not available on all ultrasound probes 4. Less sensitive than CDI and PDI in deeper organs 5. Focuses more on flow intensity over velocity	1. No information on flow directionality 2. Provided by only one manufacturer 3. It is not currently available on all ultrasound probes 4. Less sensitive than CDI and PDI in deeper organs 5. Focuses more on flow intensity over velocity

Non-contrast ultrasound assessment of blood flow in clinical practice

Figures & Tables

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Summary of various non-contrast ultrasound flow modes_ Microvascular imaging (McVI) nomenclatures used by different ultrasound manufacturers (listed alphabetically)

Summary of various non-contrast ultrasound flow modes

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