What Ultrasonic Imaging & Characterization got wrong, from 41 theses

Tried and failed

Ultrasonic pulse transmission for shear-wave arrival detection applied to sediment samples under triaxial loading. Outcome: no signal. Reason: High acoustic attenuation and internal reflections at low effective stress obscured arrival signatures

Evaluating the role of mechanical and hydrologic properties of input sediment to fluid pressure development in the shallow subduction zone · UT Austin · PhD

Tried and failed

ultrasonic guided wave inspection outside optimal frequency-thickness applied to fluid-filled pipes. Outcome: no signal. Reason: frequencies outside 1.0-1.5 MHz-mm caused excessive leaky attenuation of the A0 mode into the fluid

Pipeline health monitoring using helical guided ultrasonic waves · UT Austin · PhD

Tried and failed

ultrasonic C-scan non-destructive testing applied to thick filament-wound composite pipes. Outcome: no signal. Reason: severe acoustic attenuation and scattering in thick filament-wound glass-fiber structures prevented acceptable image clarity

Predicting impact damage in composite structures · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected standard ultrasonic bath immersion due to up to 90% acoustic intensity attenuation through module walls and membrane layers.

Ultrasonic Fouling Mitigation for Renewable Energy Powered Reverse Osmosis Desalination Systems · York University · Master's

Considered and rejected

Considered and rejected: Rejected relying on ultrasound-range (1-3 MHz) acoustic emission sensors for trans-cranial cavitation detection due to severe attenuation (10-30 dB) across the skull.

Cavitation in Blunt Traumatic Brain Injury · Duke · Doctorate

Considered and rejected

Considered and rejected: Rejected Sylgard-184 for ultrasound flow loops due to high acoustic attenuation coefficent

On the extraction of path-dependent dynamics from recirculating pulsatile flows using optical and ultrasound imaging · Queen's University · PhD

Tried and failed

spatial tracking 3D reconstruction from 2D ultrasound applied to calcified vascular lumen volume assessment. Outcome: data insufficient. Reason: acoustic shadowing behind dense calcifications created signal voids that prevented automated volume segmentation

Evaluation of tomographic 3D ultrasound for the assessment of vascular pathology · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected standard ultrasound imaging for in vivo cranial blast cavitation due to poor axial resolution, skull fusion in adult animals, and acoustic backscatter.

Biological cavitation and protein profiles as unique hallmarks of blast-induced traumatic brain injury · Iowa State · PhD

Tried and failed

delay-and-sum ultrasonic imaging applied to thick composite impact damage localization. Outcome: no signal. Reason: weak reflection from small defects combined with guided wave mode dispersion in thick media

Structural health monitoring of thick composites using ultrasonic guided waves · Imperial · PhD

Tried and failed

sensor-tracked freehand 3D ultrasound reconstruction applied to deep tissue vascular imaging. Outcome: no signal. Reason: excessive acoustic penetration depth degraded image quality beyond reconstruction software thresholds

Evaluation of tomographic 3D ultrasound for the assessment of vascular pathology · Imperial · PhD

Tried and failed

high-frequency ultrasound in viscous immersion fluid applied to acoustic reflection resolution enhancement. Outcome: worse than baseline. Reason: Fluid viscous attenuation downshifted the center frequency, eliminating high-frequency spatial resolution advantages.

High-resolution dynamic elastic properties of spatially heterogeneous rocks from measurements of angle-dependent ultrasonic reflection coefficient · UT Austin · PhD

Tried and failed

low-frequency uncontrasted ultrasound Doppler flow measurement applied to in vivo arterial blood flow. Outcome: no signal. Reason: acoustic absorption dominated over blood scattering at frequencies below 15 MHz

Compact modular open platform for low-cost ultrasound imaging · Imperial · PhD

Tried and failed

ultrasonic echo gating using early/late arrivals applied to defect imaging in layered structures. Outcome: no signal. Reason: early echoes lack defect interaction while late echoes suffer from poor signal-to-noise ratio

Ultrasonic guided waves for mechanical defects detection on thin-film solar photovoltaic modules · Georgia Tech · PhD

Tried and failed

1D scanline intensity summation applied to acoustic shadow detection in ultrasound. Outcome: did not generalise. Reason: Oversensitivity from relying on raw pixel intensities instead of dynamic spatial variations

Computer-assisted intraoperative ultrasound in brain tumour surgery · Imperial · PhD

Tried and failed

2D spatial image representation for time-series classification applied to ultrasonic non-destructive testing signal classification. Outcome: worse than baseline. Reason: Synthetic 2D image focusing added computational overhead while yielding poorer classification performance than raw 1D time-domain traces

Machine learning applications in guided wave testing · Imperial · Doctorate

Tried and failed

angular coherence factor on redundant signals applied to ultrasound aberration correction. Outcome: worse than baseline. Reason: local wave aberrations became entangled across angles, lowering contrast compared to standard coherence factor

An Angular Framework for Ultrasound Imaging · EPFL · PhD

Tried and failed

sparse wavelet regularization using iterative shrinkage thresholding applied to ultrasound image reconstruction. Reason: Altered natural speckle patterns and improperly thresholded continuous linear intensity gradients.

Ultrasound Imaging: From Physical Modeling to Deep Learning · EPFL · PhD

Tried and failed

intensity thresholding and adaptive segmentation algorithms applied to speckle-corrupted ultrasound image segmentation. Reason: acoustic speckle noise caused false vessel wall classifications and contour discontinuities

Forward-Viewing Ultrasound Guidance of a Robotically-Steered Guidewire for Peripheral Interventions · Georgia Tech · PhD

Tried and failed

training CNNs on envelope-detected data applied to ultrasound image reconstruction. Outcome: worse than baseline. Reason: envelope detection discards phase information, causing blurred speckle patterns compared to raw RF/IQ representations

Ultrasound Imaging: From Physical Modeling to Deep Learning · EPFL · PhD

Tried and failed

Image deconvolution without geometric aberration correction applied to transcranial ultrasound blood flow imaging. Reason: Disabling cranial aberration coordinate remapping caused systematic vessel diameter underestimation

Ultrasound-based Noninvasive Monitoring Methods for Neurocritical Care · MIT · PhD

Tried and failed

filtered back-projection with ramp filtering applied to plane-wave ultrasound image reconstruction. Outcome: worse than baseline. Reason: missing low-frequency components in transducer Gaussian pulses negated ramp filter benefits

An Angular Framework for Ultrasound Imaging · EPFL · PhD

Tried and failed

ultrasonic non-destructive testing applied to subsurface biological targets inside internal voids. Outcome: no signal. Reason: acoustic impedance mismatch and signal scattering across air-filled voids prevented target detection

Investigating the infestation : Understanding and communicating Deathwatch beetle activity on HMS Victory · Cranfield · PhD

Tried and failed

ultrasonic C-scan inspection applied to impact-induced kissing bond detection in laminates. Outcome: no signal. Reason: weak interface contact without acoustic impedance mismatch produced no detectable ultrasonic reflection

Low velocity and high velocity impact of composites and fibre metal laminates for commercial aircraft structures · Imperial · PhD

Tried and failed

motor oil acoustic couplant applied to high-temperature ultrasonic guided wave testing. Outcome: no signal. Reason: high ultrasonic wave attenuation and absorption at elevated temperatures

Influence of dynamic load and temperature on guided wave ultrasonic damage detection in thin plates · Cranfield · PhD

Considered and rejected

Considered and rejected: Rejected glass tubes and acrylic blocks due to acoustic impedance mismatch and non-physiological ultrasound representation.

Entwicklung eines kostengünstigen Phantoms für das Erlernen der Dopplersonografie Development of a low-cost phantom for learning Doppler sonography · University of Marburg · PhD

Tried and failed

applying retro-reflective tape for optical detection applied to ultrasonic surface wave measurements. Outcome: worse than baseline. Reason: introduced excessive high-frequency acoustic damping and thickness calibration errors

Texture characterisation in metals using diffuse ultrasound · Imperial · Doctorate

Considered and rejected

Considered and rejected: Rejected glass coverslips for ultrasound imaging due to severe acoustic impedance mismatch (c=5600 m/s, rho=2200 kg/m3) causing total reflection; switched to PDMS coverslips

Ultrasound imaging of cells using gas vesicles and perfluorocarbon nanodroplets · Georgia Tech · PhD

Tried and failed

Viscoelastic couplant for external absorbing boundaries applied to ultrasonic wave absorption. Reason: Large acoustic impedance mismatch and requirement of an unrealistically thin coupling layer.

Ultrasonic methods for assessing fatigue degradation in metals · Imperial · PhD

Tried and failed

elastomer adhesive bonding for acoustic coupling applied to ultrasonic acoustic power transfer interfaces. Outcome: worse than baseline. Reason: adhesive layer introduced bonding defects and trapped air bubbles, degrading acoustic transmission efficiency

Acoustic Power Transfer Leveraging Piezoelectricity and Metamaterials · Georgia Tech · PhD

Tried and failed

dry-coupled mechanical clamping of piezoelectric transducers applied to ultrasonic guided wave structural monitoring. Outcome: worse than baseline. Reason: produced order of magnitude lower voltage amplitude and significantly worse signal stability than adhesive bonding

The use of circumferential guided waves to monitor axial cracks · Imperial · Doctorate

Lost to a baseline

Ultrasound detected caliber variations in only 42.77% of cases compared to 82.64% detected by MRCP and 98.68% by ERCP

Sonographische Befunde bei Patienten mit primär sklerosierender Cholangitis · Tübingen · PhD

Lost to a baseline

Radiography showed higher interobserver agreement (Gwet's AC1 0.9215-0.9423) than ultrasound (0.4486).

Ultrasonographic evaluation of sites of osteochondrosis in young Thoroughbred horses · University College Dublin · PhD

Lost to a baseline

For fetal lens visualization, 2D ultrasound outperformed 3D ultrasound across 12–14 weeks (2D achieved 95% vs 3D at 39%).

A prospective three-dimensional imaging and anatomy screening study · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected intravascular ultrasound (IVUS) imaging in favor of optical coherence tomography (OCT) due to resolution limitations (100-120 microns for IVUS vs 10 microns for OCT).

ATHERO52, A Proof of Concept Device Design to Remove and Treat Atherosclerosis with a Non-Invasive Surgical Approach · Harvard · Master's

Lost to a baseline

Conventional ultrasonic C-scan achieves 1 mm x 1 mm spatial resolution, resolving exact crack morphology which Lamb wave scanning cannot.

Ultrasonic guided waves for mechanical defects detection on thin-film solar photovoltaic modules · Georgia Tech · PhD

Tried and failed

two-dimensional ultrasound diameter reduction measurement applied to transplant renal artery stenosis diagnosis. Outcome: worse than baseline. Reason: planar measurements yielded low diagnostic accuracy compared to volumetric and magnetic resonance angiography assessments

The evaluation of advanced ultrasonography applications in the assessment of transplanted kidneys · Imperial · PhD

Tried and failed

conventional colour Doppler ultrasound imaging applied to inter-cord placental vascular anastomoses. Outcome: no signal. Reason: insufficient sensitivity and resolution to detect slow microvascular blood flow between umbilical cords

Placental Vascular imaging and its association with pregnancy outcomes · Imperial · Doctorate

Tried and failed

linear ultrasonic guided wave damage detection applied to crack detection under varying environmental temperatures. Outcome: no signal. Reason: signal changes from temperature drift masked or mimicked damage-induced acoustic feature changes

Baseline-free structural health monitoring in aeronautical structures under in-service conditions · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected relying solely on ultrasonic signal amplitude/intensity for long-term battery monitoring due to vulnerability to transducer deterioration and temperature fluctuations, choosing relative wave attenuation instead.

Ultrasonic monitoring of temperature distributions and degradation in engineering components · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected active pulse-laser and air-coupled ultrasonic transmitters due to high cost, maintenance difficulty, and acoustic reverberation noise degrading SNR above 2.4 km/h

Development of a new laser doppler vibrometer-based non-contact damage detection system for cracks in rail head · UT Austin · PhD

Tried and failed

pulse-based phased array wave mixing applied to nonlinear ultrasound characterization of metals. Outcome: no signal. Reason: off-frequency spectral components and lack of precise polarity control prevented harmonic extraction

Nonlinear ultrasound for the characterization of additively manufactured metals · Georgia Tech · PhD

Considered and rejected

Considered and rejected: Single-frequency ultrasound transducers with electronic second-harmonic filtering, rejected due to residual acoustic noise in the signal in favour of pulse inversion / phase-shift harmonic imaging

Evaluation of tomographic 3D ultrasound for the assessment of vascular pathology · Imperial · PhD

Considered and rejected

Considered and rejected: Freehand 3D ultrasound without position sensors, rejected because lack of positional data yields inadequate volumetric reconstruction quality preventing quantitative measurements

Evaluation of tomographic 3D ultrasound for the assessment of vascular pathology · Imperial · PhD

Tried and failed

multipulse harmonic filtering for tissue clutter cancellation applied to row-column array ultrasound imaging. Reason: transducer element elongation and hardware system non-linearities limited suppression to 30-35 dB instead of clinical 50-60 dB

Ultrafast 3-D ultrasound super-resolution imaging with a row-column array · Imperial · PhD

Tried and failed

ultrasonic guided-wave time-of-flight-shift tracking applied to lithium-ion pouch cells. Outcome: no signal. Reason: low signal amplitude and high noise from the specific transducer geometry configuration

Ultrasonic and vibrational methods to determine changes of state of lithium-ion cells · UT Austin · PhD

Tried and failed

purely resistive electrical impedance matching applied to capacitive ultrasound transducer interfaces. Outcome: worse than baseline. Reason: suboptimal acoustic and electrical reflectivity resulted in over 12 dB worse echo-receive efficiency than negative capacitance matching

Integrated Electronics for Wireless Imaging Microsystems with CMUT Arrays · Georgia Tech · PhD

Considered and rejected

Considered and rejected: Rejected lossy backing materials (standard in ultrasound) due to losing up to 50% incident acoustic energy, selecting air backing instead.

Piezoelectric Acoustic Identification Tags with Frequency Multiplexed Energy Harvesting and Backscatter Communication Operation for Underwater Applications · Georgia Tech · PhD

Left open

Investigate why acoustic power transfer improvement is negligible below 39 kHz when piezoelectric transducer reactance is inductive. Blocker: Requires a physical experimental ultrasonic power transfer testbed with specific piezoelectric transducers (FUS-40E)

Acoustic power distribution techniques for wireless sensor networks · Imperial · Doctorate

Left open

Evaluate guided wave ultrasonic testing parameters for breathing cracks in corroded plate regions under varying temperature conditions. Blocker: Requires experimental ultrasonic testing apparatus (PZT transducers, temperature chamber, corroded/cracked specimens) or complex uncalibrated multi-physics modeling.

Influence of dynamic load and temperature on guided wave ultrasonic damage detection in thin plates · Cranfield · PhD

Left open

Optimize ultrasonic horn dimensions and cross-sectional geometries using acoustic and structural simulations for reverse osmosis fouling mitigation. Blocker: Lack of specific target performance metrics, objective functions, and constraints

Ultrasonic Fouling Mitigation for Renewable Energy Powered Reverse Osmosis Desalination Systems · York University · Master's

Left open

Investigate guided wave ultrasonic damage detection in thin plates under combined dynamic stress and temperature variations. Blocker: Requires a physical testing apparatus with ultrasonic transducers and thermomechanical loading capabilities

Influence of dynamic load and temperature on guided wave ultrasonic damage detection in thin plates · Cranfield · PhD

Left open

Combine ultrasonic backscattering measurements with phase velocity estimates into a unified materials characterisation framework for superalloys. Blocker: Requires ultrasonic physical testing apparatus, transducers, water tank setup, and physical superalloy specimens to perform backscattering measurements.

Phase characterisation of nickel-based superalloys using ultrasound · Imperial · Doctorate

Left open

Develop a method comparing relative ultrasonic guided wave mode amplitudes to characterize defect sizing and orientation. Blocker: Requires ultrasonic phased array hardware, transducer wedges, and experimental defect specimens for validation

Phased array implementation of high frequency, multi-mode dispersion compensation for ultrasonic guided wave inspections · Iowa State · PhD

Left open

Assess whether the ratio of SH0 to axially propagating S0 wave amplitude and phase remains proportional and stable across hardware variations. Blocker: Requires physical ultrasonic transducers, pipe testing apparatus, and hardware variations to measure wave modes.

The use of circumferential guided waves to monitor axial cracks · Imperial · Doctorate

Left open

Correlate measured nonlinear ultrasound beta parameters with material microstructures for selective damage assessment in additively manufactured metals. Blocker: Requires physical experimental ultrasound hardware, wedge transducers, and AM metal samples for microstructure characterization

Nonlinear ultrasound for the characterization of additively manufactured metals · Georgia Tech · PhD

Left open

Identify sources of discrepancy between SRAS and bulk experimental surface acoustic wave velocity measurements in Ti-5Al-5Mo-5V-3Cr samples. Blocker: Requires physical ultrasonic testing equipment, SRAS experimental setup, and specific alloy samples

Ultrasonic characterization of Ti-5Al-5Mo-5V-3Cr · Iowa State · Master's

Left open

Test helical guided ultrasonic waves on liquid-filled, pressurized pipes and examine the effects of coatings, pressure, vibrations, and bends. Blocker: Requires specialized physical experimental setup with pressurized liquid-filled pipes, ultrasonic transducers, and structural testbeds

Pipeline health monitoring using helical guided ultrasonic waves · UT Austin · PhD