Ultrasound Contrast Stability for Urinary Bladder Pressure Measurement

Kalayeh, Kourosh; Fowlkes, J. Brian; Claflin, Jake; Fabiilli, Mario L.; Schultz, William W.; Sack, Bryan S.

doi:10.1016/j.ultrasmedbio.2022.08.008

Cited by 10 publications

(13 citation statements)

References 44 publications

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“…The variability of SHAPE conversion factor is not only because of different scanning conditions (eg, US path, attenuation level, scanning depth, etc) but an inherent variability in MB size distribution among vials. The latter is illustrated and discussed in our previous study 24 . Irrespective of presence or lack of SHAPE conversion factor variability, the excellent correlation between SHAPE and bladder phantom pressure obtained in this study for every CMG event and every tested vial of MB demonstrates that MB SH emission is a good indicator of bladder phantom pressure variation and proves that SHAPE is capable of predicting bladder phantom pressure.…”

Section: Discussionsupporting

confidence: 66%

“…The latter is illustrated and discussed in our previous study. 24 Irrespective of presence or lack of SHAPE conversion factor variability, the excellent correlation between SHAPE and bladder phantom pressure obtained in this study for every CMG event FIGURE 4. SHAPE calibration curves obtained from 3 vials of microbubbles tested in this study.…”

Section: Discussionmentioning

confidence: 59%

“…We have previously shown that the CMG infusion system—consisting of a peristaltic pump and a catheter—has an adverse effect on MB stability, 24 and to ensure MB stability during a typical CMG test (≈30 minutes), higher MB dosage is needed (limited by shadowing artifact and current FDA approved dosage). In the same study, we showed that, for these lipid-shelled MBs, a dilution factor of DF = 1:1667 is optimal for sufficient MB stability to obtain SH signal over the whole duration of a typical CMG.…”

Section: Methodsmentioning

confidence: 99%

“…As will be shown later, during a typical simulated CMG in this study, MB SH signal decreases by more than 15 dB over 30 minutes. This is partially because of MBs natural decay 30,31 and partially and more importantly because of the adverse effects of the CMG infusion system on MBs 24 . This temporal decrease of MB SH signal needs to be considered when calculating change in SH for SHAPE application.…”

Section: Methodsmentioning

confidence: 99%

“…This is partially because of MBs natural decay 30,31 and partially and more importantly because of the adverse effects of the CMG infusion system on MBs. 24 This temporal decrease of MB SH signal needs to be considered when calculating change in SH for SHAPE application.…”

Section: Shape Protocolmentioning

confidence: 99%

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Pressure Measurement in a Bladder Phantom Using Contrast-Enhanced Ultrasonography—A Path to a Catheter-Free Voiding Cystometrogram

Kalayeh¹,

Fowlkes²,

Chen³

et al. 2022

Invest Radiol

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ObjectivesThe long-term goal of this study is to investigate the efficacy of a novel, ultrasound-based technique called subharmonic-aided pressure estimation (SHAPE) to measure bladder pressure as a part of a cystometrogram (CMG) in a urodynamic test (ie, pressure-flow study). SHAPE is based on the principle that subharmonic emissions from ultrasound contrast microbubbles (MBs) decrease linearly with an increase in ambient pressure. We hypothesize that, using the SHAPE technique, we can measure voiding bladder pressure catheter-free. This is of importance because the CMG catheter, due to its space-occupying property and non-physiological effects, can undermine the reliability of the test during voiding and cause misdiagnosis. In this study, we tested this hypothesis and optimized the protocol in a controlled benchtop environment.Materials and MethodsA bladder phantom was designed and built, capable of simulating clinically relevant bladder pressures. Laboratory-made lipid-shelled MBs (similar in composition to the commercial agent, DEFINITY) was diluted in 0.9% normal saline and infused into the bladder phantom using the CMG infusion system. A typical simulated CMG consists of 1 filling and 4 post-filling events. During CMG events, the bladder phantom is pressurized multiple times at different clinically relevant levels (small, medium, and large) to simulate bladder pressures. Simultaneous with pressurization, MB subharmonic signal was acquired. For each event, the change in MB subharmonic amplitude was correlated linearly with the change in bladder phantom pressure, and the SHAPE conversion factor (slope of the linear fit) was determined. In doing so, a specific signal processing technique (based on a small temporal window) was used to account for time-decay of MB subharmonic signal during a simulated CMG.ResultsA strong inverse linear relationship was found to exist between SHAPE and bladder phantom pressures for each of the CMG filling and post-filling events (r2 > 0.9, root mean square error <0.3 dB, standard error <0.01 dB, and P < 0.001). SHAPE showed a transient behavior in measuring bladder phantom pressure. The SHAPE conversion factor (in dB/cm H2O) varied between filling and post-filling events, as well as by post-filling time. The magnitude of the SHAPE conversion factor tended to increase immediately after filling and then decreases with time.ConclusionsMicrobubble subharmonic emission is an excellent indicator of bladder phantom pressure variation. The strong correlation between SHAPE signal and bladder phantom pressure is indicative of the applicability of this method in measuring bladder pressure during a CMG. Our results suggest that different SHAPE conversion factors may be needed for different events during a CMG (ie, at different time points of a CMG). These findings will help us better protocolize this method for introduction into human subjects and allow us to take the next step toward developing a catheter-free voiding CMG using SHAPE.

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Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 59%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%