Three-dimensional US Fractional Moving Blood Volume: Validation of Renal Perfusion Quantification

Abstract

N umerous pathologic states are characterized by altered vascularity (number of blood vessels per unit tissue volume) or perfusion (expressed as volume blood flow [in milliliters per second] per unit tissue mass [in milliliters per kilogram per second]). No easily available clinical tool exists for quantification of tissue or organ blood flow and perfusion.Perfusion estimation with use of near-infrared spectroscopy, MRI, or CT has been attempted, but there are several challenges for clinical adoption. Near-infrared spectroscopy provides no visual display to indicate the anatomic site where tissue oxygenation is being measured. MRI allows imaging but is inherently expensive, temporally and spatially limited, and dependent on the type of sequence used (arterial spin labeling or blood oxygenation level-dependent). CT requires ionizing radiation and a tracer. US would therefore be an obvious candidate for noninvasive volumetric perfusion imaging that can be performed in most clinical settings. With a validated method, the ability to understand where organ perfusion has changed versus absolute measurements (against a known reference range), or as relative measurements (eg, in response to therapy or surgery, including transplantation), would be valuable for detecting perfusion changes and determining their severity and lead to earlier interventions. These would have obvious applications in emergency care, transplantation, and oncology, where estimation of perfusion would be a useful additional diagnostic tool.Power Doppler US has advantages for flow quantification because of its ability to depict low-velocity signals and multidirectional flow and its lack of aliasing (1). Sources of error include signal attenuation due to depth and patient habitus and tissue inhomogeneity, which reduces the possibility for comparison over time or between patients. To compensate, a technique called

Ultrasonographic tissue perfusion analysis at implant and palatal donor sites following soft tissue augmentation: A clinical pilot study

“…Among the limitations of the present pilot study, the inclusion of a single light smoker (even though CPPD variations at the implant-and palatal donor site did not show a substantial difference compared to the other subjects) have to be noted. In addition, although the presented method has already been shown to be reliable and it has been validated in the medical field (Carson et al, 1998;Fleischer et al, 1999;Gao et al, 2013;Welsh et al, 2019), future studies comparing power Doppler US and other techniques, such as fluorescein angiography or laser-Doppler flowmetry, for tissue perfusion evaluation at implant and palatal sites are needed. Future studies may benefit from power Doppler US for evaluating tissue perfusion during different phases of periodontal/ peri-implant healing, diagnosis of pathological conditions or subclinical inflammation.…”

“…This new scanning‐angle independent approach integrates the colour flow power spectrum which extends the dynamic range and increases the machine's sensitivity to blood flow versus the traditional mean frequency estimator that is prone to noise for reduced flow (Rubin et al, 1994; Bude et al, 1994; Newman et al, 1994). In addition, power Doppler ultrasound has advantages for blood‐flow (colour and power) quantification because of its ability to depict low‐velocity signals and multidirectional flow and its lack of aliasing (Rubin et al, 1994; Welsh et al, 2019). To compensate for possible signal attenuation due to depth and tissue inhomogeneity, a method termed fractional moving blood volume (FMBV) has been established (Rubin et al, 1995; Welsh, 2004).…”

“…To compensate for possible signal attenuation due to depth and tissue inhomogeneity, a method termed fractional moving blood volume (FMBV) has been established (Rubin et al, 1995; Welsh, 2004). This technique is based on the cumulative power distribution function to define a stable intra‐vascular point, providing an absolute value for vascularity for inter‐ and intra‐case comparisons (Rubin et al, 1997; Welsh et al, 2019). FMBV evaluation requires an offline image analysis technique applied to raw exported three‐dimensional (3D) power Doppler US (Stevenson et al, 2015; Welsh et al, 2019).…”

“…This technique is based on the cumulative power distribution function to define a stable intra‐vascular point, providing an absolute value for vascularity for inter‐ and intra‐case comparisons (Rubin et al, 1997; Welsh et al, 2019). FMBV evaluation requires an offline image analysis technique applied to raw exported three‐dimensional (3D) power Doppler US (Stevenson et al, 2015; Welsh et al, 2019). This method has been used to assess blood flow and perfusion of the kidney (Welsh et al, 2019), optic nerve (Vosborg et al, 2020), placenta (Lai et al, 2010) and foetal organs (Hernandez‐Andrade, Thuring‐Jonsson, et al, 2004; Hernandez‐Andrade et al, 2007), among others.…”

Fully Automated 3-D Ultrasound Segmentation of the Placenta, Amniotic Fluid, and Fetus for Early Pregnancy Assessment

“…There is a clinical need for a precise, fully automated, method for real-time 3D-US image segmentation which can be used to provide an estimation of placental volume and demarcate its boundaries (enable identification of the interface between placenta and uterus, thereby providing the basis for automated perfusion assessment [9], [10]). These imaging biomarkers could then be incorporated into a multi-factorial population-based screening test to improve early prediction of adverse pregnancy outcomes.…”