A Novel Microvascular Flow Technique

Abstract

To evaluate the flow imaging capabilities of a new prototype ultrasound (US) image processing technique (superb micro-vascular imaging [SMI]; Toshiba Medical Systems, Tokyo, Japan) for depiction of microvascular flow in normal thyroid tissue and thyroid nodules compared with standard color and power Doppler US imaging.Ten healthy volunteers and 22 patients, with a total of 25 thyroid nodules, scheduled for US-guided fine needle aspiration were enrolled in this prospective study. Subjects underwent US examination consisting of grayscale, color and power Doppler imaging (CDI and PDI) followed by color and monochrome SMI and pulsed Doppler. SMI is a novel, microvascular flow imaging mode implemented on the Aplio 500 US system (Toshiba). SMI uses advanced clutter suppression to extract flow signals from large to small vessels and depicts this information at high frame rates as a color overlay image or as a monochrome map of flow. Two radiologists independently scored still images and digital clips for overall flow detection, vessel branching details and noise on a visual-analog scale of 1 (worst) to 10 (best).For the volunteers SMI visualized microvasculature with significantly lower velocity than CDI and PDI (P < 0.012). In all thyroid nodules, SMI demonstrated microvascular flow with significantly higher image scores and provided better depiction of the vessel branching details compared with CDI and PDI (P < 0.0001). Clutter noise was significantly higher in monochrome SMI mode than in the other modes, including color SMI (P < 0.001).The novel SMI mode consistently improved the depiction of thyroid microvascular flow compared with standard CDI and PDI.

Application of a Novel Microvascular Imaging Technique in Breast Lesion Evaluation

“…Furthermore, SMI revealed more details of microvasculature, such as tiny branches and the distal part of microvessels. Therefore, our findings extended SMI's previous applications in thyroid and breast masses (Ma et al 2015;Machado et al 2016;Zhan et al 2016). The advantages of SMI are due largely to its ability to separate low-speed flow signals from motion artifacts.…”

“…The principle underlying SMI is a powerful and intelligent algorithm that effectively separates low-speed flow signals from motion artifacts so that it can display real flow signals in microvessels. SMI accurately depicts low-speed flow signals in thyroid lesions (Machado et al 2016) and matches contrastenhanced computer tomography in the diagnosis of focal nodular hyperplasia (Wu et al 2015). Its preliminary application in breast cancer further suggested its diagnostic value (Ma et al 2015;Zhan et al 2016).…”

Diagnostic Performance of Superb Microvascular Imaging (SMI) Combined with Shear-Wave Elastography in Evaluating Breast Lesions

“…With the progress in ultrasonography, SMI as a pioneering technique shows the ability to visualize lower-peed bloodstreams without motion artifacts. Such an advantage has been widely proved in examining microvascular flow in thyroid nodules [8], renal tumor vascularity [9], testicle blood flow of small children [10], and focal liver lesion vascularity [11]. Therefore, various studies supported the performance of SMI in depicting the minute vessels and slow-speed blood flows with high resolution and fewer motion artifacts.…”

Microvessel ultrasound of neonatal brain parenchyma: feasibility, reproducibility, and normal imaging features by superb microvascular imaging (SMI)

“…SMI has evolved as a novel tool for non-invasive imaging of microvasculature without the use of intravenous contrast material [14]. The method uses advanced clutter suppression and processes low flow Doppler signals that are otherwise filtered and removed as “clutter”.…”