A Novel Method for Angiographic Contrast-Based Diagnosis of Stenosis in Coronary Artery Disease: In Vivo and In Vitro Analyses.

BACKGROUND: The existing diagnostic methods for coronary artery disease (CAD), such as coronary angiography and fractional flow reserve (FFR), have limitations regarding their invasiveness, cost, and discomfort. We explored a novel diagnostic approach, coronary contrast intensity analysis (CCIA), and conducted a comparative analysis between it and FFR. METHODS: We used an in vitro coronary-circulation-mimicking system with nine stenosis models representing various stenosis lengths (6, 18, and 30 mm) and degrees (30%, 50%, and 70%). The angiographic brightness values were analyzed for CCIA. The in vivo experiments included 15 patients with a normal sinus rhythm. Coronary angiography was performed, and arterial movement was tracked, enabling CCIA derivation. The CCIA values were compared with the FFR (n = 15) and instantaneous wave-free ratio (iFR; n = 11) measurements. RESULTS: In vitro FFR showed a consistent trend related to the length and severity of stenosis. The CCIA was related to stenosis but had a weaker correlation with length, except for with 70% stenosis (6 mm: 0.82 ± 0.007, 0.68 ± 0.007, 0.61 ± 0.004; 18 mm: 0.78 ± 0.052, 0.69 ± 0.025, 0.44 ± 0.016; 30 mm: 0.80 ± 0.018, 0.64 ± 0.006, 0.40 ± 0.026 at 30%, 50%, and 70%, respectively). In vitro CCIA and FFR were significantly correlated (R = 0.9442, p < 0.01). The in vivo analysis revealed significant correlations between CCIA and FFR (R = 0.5775, p < 0.05) and the iFR (n = 11, R = 0.7578, p < 0.01). CONCLUSIONS: CCIA is a promising alternative for diagnosing stenosis in patients with CAD. The initial in vitro validation and in vivo confirmation in patients demonstrate the feasibility of applying CCIA during coronary angiography. Further clinical studies are warranted to fully evaluate the diagnostic accuracy and potential impact of CCIA on CAD management.

Reply to Marino et al. Choroidal Thickness Measurements in the Case of Diabetic Macular Edema. Comment on "Amjad et al. Choroidal Thickness in Different Patterns of Diabetic Macular Edema. J. Clin. Med. 2022, 11, 6169".

We are pleased to see that Marino et al. have written a Comment: "Choroidal Thickness Measurements in the Case of Diabetic Macular Edema" [...].

Axial shear rate: A hemorheological factor for erythrocyte aggregation under Womersley flow in an elastic vessel based on numerical simulation.

Erythrocyte aggregation (EA) is a highly dynamic, vital phenomenon to interpreting human hemorheology, which would be helpful for the diagnosis and prediction of circulatory anomalies. Previous studies of EA on erythrocyte migration and the Fåhraeus Effect are based on the microvasculature. They have not considered the natural pulsatility of the blood flow or large vessels and mainly focused on shear rate along radial direction under steady flow to comprehend the dynamic properties of EA. To our knowledge, the rheological characteristics of non-Newtonian fluids under Womersley flow have not reflected the spatiotemporal behaviors of EA or the distribution of erythrocyte dynamics (ED). Hence, it needs to interpret the ED affected by temporal and spatial flow variation to understand the effect of EA under Womersley flow. Here, we demonstrated the numerically simulated ED to decipher EA's rheological role in axial shear rate under Womersley flow. In the present study, the temporal and spatial variations of the local EA were found to mainly depend on the axial shear rate under Womersley flow in an elastic vessel, while mean EA decreased with radial shear rate. The localized distribution of parabolic or M-shape clustered EA was found in a range of the axial shear rate profile (-15 to 15s-1) at low radial shear rates during a pulsatile cycle. However, the linear formation of rouleaux was realized without local clusters in a rigid wall where the axial shear rate is zero. In vivo, the axial shear rate is usually considered insignificant, especially in straight arteries, but it has a great impact on the disturbed blood flow due to the geometrical properties, such as bifurcations, stenosis, aneurysm, and the cyclic variation of pressure. Our findings regarding axial shear rate provide new insight into the local dynamic distribution of EA, which is a critical player in blood viscosity. These will provide a basis for the computer-aided diagnosis of hemodynamic-based cardiovascular diseases by decreasing the uncertainty in the pulsatile flow calculation.

Electroencephalographic Response of Brain Stimulation by Shock Waves From Laser Generated Carbon Nanotube Transducer.

Neuromodulation is used to treat neurological disorders. Focused ultrasound can deliver acoustic energy to local regions of the brain, including deep brain structures. In addition, it is possible to induce the activation or inhibition of nerves through parameter adjustments of focused ultrasound. Laser-generated focused ultrasound (LGFUS) has demonstrated a potential use in precise therapeutic ultrasound applications owing to the ability to produce high-pressure, broadband frequency of shock waves with a tight focal spot, resulting in confined acoustic exposure of a small area. However, there have been few studies of neurostimulation using shock waves with pulse durations of several nanoseconds. The purpose of this study is to investigate the possibility of neurostimulation by shock waves generated from a focused Carbon Nanotube (fCNT) transducer. We measured electroencephalographic (EEG) signals in three rat brains before and after shock wave stimulation and compared them in the time and frequency domains. In the time domain, the number of peaks of EEG signals was measured significantly higher after shock wave stimulation than before stimulation in all three rats. The three rats showed differences in three frequency bands: theta(4-7 Hz), alpha(8-12), and 1-30 Hz, before and after shock wave stimulation (p < 0.001). These differences in EEG signals after shock wave stimulation of three rats were confirmed mainly because of shock waves. The stimulation of a rat brain was feasible using shock waves generated by the fCNT transducer. This study provides a basis for the applications of shock waves to brain stimulation for precise targeting.

Improving Sonication Efficiency in Transcranial MR-Guided Focused Ultrasound Treatment: A Patient-Data Simulation Study.

The potential improvement in sonication efficiency achieved by tilting the focused ultrasound (FUS) transducer of the transcranial MR-guided FUS system is presented. A total of 56 cases of patient treatment data were used. The relative position of the clinical FUS transducer to the patient's head was reconstructed, and region-specific skull density and porosity were calculated based on the patient's CT volume image. The total transmission coefficient of acoustic waves emitted from each channel was calculated. Then, the total energy penetrating the human skull-which represents the sonication efficiency-was estimated. As a result, improved sonication efficiency was by titling the FUS transducer to a more appropriate angle achieved in all 56 treatment cases. This simulation result suggests the potential improvement in transcranial-focused ultrasound treatment by simply adjusting the transducer angle.

Production enhancement of human adipose-derived mesenchymal stem cells by low-intensity ultrasound stimulation.

Low-intensity ultrasound (LIUS) enhances the proliferation rate of various mammalian stem cells through mechanical stimulation. This study quantitively finds suitable LIUS stimulation parameters for increasing the proliferation rate of human adipose-derived mesenchymal stem cells (hAdMSCs) for mass production. Various stimulation conditions of LIUS were assessed based on the beam pattern of the ultrasonic transducer and the attenuation of the sound waves. Using optimal LIUS stimulation parameters for enhancing proliferation of hAdMSCs taken from bromodeoxyuridine (BrdU) incorporation assay, long-term culture of hAdMSCs was performed for 16 days. The resultant hAdMSCs were characterized for various biomarkers such as CD34-, CD45-, CD73+, CD95+, CD105+ and cytological staining and a cytokine array assay. LIUS stimulation parameters found for enhancing the hAdMSCs proliferation were the frequency of 5 MHz, an intensity of 300 mWcm-2, a duration of 10 min per day, and continuous waves with a 100% duty cycle. The LIUS stimulated hAdMSCs group showed a 3.25-fold increase in the cell number compared to the control group after 16 days of culture. By confirming the effects of quantitatively measured LIUS stimulation on the enhancement of hAdMSCs proliferation, this study may be a foundation for the applications of LIUS stimulation in the industrial-scale production of hAdMSCs.

Choroidal Thickness in Different Patterns of Diabetic Macular Edema.

This observational study investigated the changes in choroidal thickness (ChT) in different patterns of diabetic macular edema (DME) based on image processing using enhanced-depth imaging spectral-domain optical coherence tomography (EDI-SD-OCT). Participants with ocular conditions affecting the fundus view, including retinal diseases, were excluded. After observing the patient's medical record, multicolor fundus photos, thickness maps, and subtypes of DME were diagnosed according to the criteria reported by the Early Treatment Diabetic Retinopathy Study (ETDRS). Edema was classified as focal or diffuse and was subdivided into cystic macular edema (CME), CME with subretinal fluid (CME+), and spongy macular edema (SME). Image processing was performed on the B-scan images from SD-OCT to segment the choroid layer and obtain the choroid thickness. A total of 159 eyes of 81 patients (46 males and 35 females; 57.53 ± 9.78 years of age), and 57 eyes of 30 healthy individuals (age 57.34 ± 8.76 years) were enrolled in this study. Out of 159 eyes, 76 had focal macular edema (FME), 13 exhibited SME, and 51 presented CME. Among those with cystic macular edema, 19 eyes showed subretinal fluid (CME+). The average choroidal thickness in FME, diffuse SME, CME, and CME+ was 216.95 ± 52.94 µm, 243.00 ± 46.34 µm, 221.38 ± 60.78 µm, and 249.63 ± 53.90 µm, respectively. The average choroidal thickness in age-matched controls was 213.88 ± 45.60 µm. Choroidal thickness increases with the severity of edema; choroidal thickness was higher in diffuse macular edema than in FME. However, choroidal thickness increased in cystic macular edema with subretinal fluid (CME+).

Numerical simulation of spatiotemporal red blood cell aggregation under sinusoidal pulsatile flow.

Previous studies on red blood cell (RBC) aggregation have elucidated the inverse relationship between shear rate and RBC aggregation under Poiseuille flow. However, the local parabolic rouleaux pattern in the arterial flow observed in ultrasonic imaging cannot be explained by shear rate alone. A quantitative approach is required to analyze the spatiotemporal variation in arterial pulsatile flow and the resulting RBC aggregation. In this work, a 2D RBC model was used to simulate RBC motion driven by interactional and hydrodynamic forces based on the depletion theory of the RBC mechanism. We focused on the interaction between the spatial distribution of shear rate and the dynamic motion of RBC aggregation under sinusoidal pulsatile flow. We introduced two components of shear rate, namely, the radial and axial shear rates, to understand the effect of sinusoidal pulsatile flow on RBC aggregation. The simulation results demonstrated that specific ranges of the axial shear rate and its ratio with radial shear rate strongly affected local RBC aggregation and parabolic rouleaux formation. These findings are important, as they indicate that the spatiotemporal variation in shear rate has a crucial role in the aggregate formation and local parabolic rouleaux under pulsatile flow.

The reasons why fractional flow reserve and instantaneous wave-free ratio are similar using wave separation analysis.

BACKGROUND AND OBJECTIVES: Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are the two most commonly used coronary indices of physiological stenosis severity based on pressure. To minimize the effect of wedge pressure (Pwedge), FFR is measured during hyperemia conditions, and iFR is calculated as the ratio of distal and aortic pressures (Pd/Pa) in the wave-free period. The goal of this study was to predict Pwedge using the backward wave (Pback) through wave separation analysis (WSA) and to reflect the effect of Pwedge on FFR and iFR to identify the relationship between the two indices. METHODS: An in vitro circulation system was constructed to calculate Pwedge. The measurements were performed in cases with stenosis percentages of 48, 71, and 88% and with hydrostatic pressures of 10 and 30 mmHg. Then, the correlation between Pback by WSA and Pwedge was calculated. In vivo coronary flow and pressure were simultaneously measured for 11 vessels in all patients. The FFR and iFR values were reconstructed as the ratios of forward wave at distal and proximal sites during hyperemia and at rest, respectively. RESULTS: Based on the in vitro results, the correlation between Pback and Pwedge was high (r = 0.990, p < 0.0001). In vivo results showed high correlations between FFR and reconstructed FFR (r = 0.992, p < 0.001) and between iFR and reconstructed iFR (r = 0.930, p < 0.001). CONCLUSIONS: Reconstructed FFR and iFR were in good agreement with conventional FFR and iFR. FFR and iFR can be expressed as the variation of trans-stenotic forward pressure, indicating that the two values are inferred from the same formula under different conditions.

A Systemic Review of Available Low-Cost EEG Headsets Used for Drowsiness Detection.

Drowsiness is a leading cause of traffic and industrial accidents, costing lives and productivity. Electroencephalography (EEG) signals can reflect awareness and attentiveness, and low-cost consumer EEG headsets are available on the market. The use of these devices as drowsiness detectors could increase the accessibility of safety and productivity-enhancing devices for small businesses and developing countries. We conducted a systemic review of currently available, low-cost, consumer EEG-based drowsiness detection systems. We sought to determine whether consumer EEG headsets could be reliably utilized as rudimentary drowsiness detection systems. We included documented cases describing successful drowsiness detection using consumer EEG-based devices, including the Neurosky MindWave, InteraXon Muse, Emotiv Epoc, Emotiv Insight, and OpenBCI. Of 46 relevant studies, ~27 reported an accuracy score. The lowest of these was the Neurosky Mindwave, with a minimum of 31%. The second lowest accuracy reported was 79.4% with an OpenBCI study. In many cases, algorithmic optimization remains necessary. Different methods for accuracy calculation, system calibration, and different definitions of drowsiness made direct comparisons problematic. However, even basic features, such as the power spectra of EEG bands, were able to consistently detect drowsiness. Each specific device has its own capabilities, tradeoffs, and limitations. Widely used spectral features can achieve successful drowsiness detection, even with low-cost consumer devices; however, reliability issues must still be addressed in an occupational context.

Attenuation of the human skull at broadband frequencies by using a carbon nanotube composite photoacoustic transducer.

The shockwave generated from a focused carbon nanotube (CNT) composite photoacoustic transducer has a wide frequency band that reaches several MHz in a single pulse. The objective of this study was to measure the transmission characteristics of a shockwave generated by a CNT composite photoacoustic transducer through Asian skulls and compare the results with numerical simulation ones. Three Korean cadaver skulls were used, and five sites were measured for each skull. The average densities and sound speeds of the three skulls were calculated from computed tomography images. The sound pressure after skull penetration was about 11% of the one before skull penetration. High-frequency energy was mostly attenuated. The average attenuation coefficients measured at the five sites of the three skulls were 3.59 ± 0.29, 5.99 ± 1.07, and 3.90 ± 0.86 np/cm/MHz. These values were higher than those previously measured at 270, 836, and 1402 kHz from other groups. The attenuation coefficients simulated by Sim4life were slightly smaller than the experimental values, with similar trends at most sites. The attenuation coefficients varied with measurement sites, skull shape, and thickness. These results may provide important data for future applications of shockwaves in noninvasive neurological treatments.

An open-source phase correction toolkit for transcranial focused ultrasound.

BACKGROUND: The phase correction on transcranial focused ultrasound is essential to regulate unwanted focal point shift caused by skull bone aberration. The aim of the current study was to design and investigate the feasibility of a ray-based phase correction toolkit for transcranial focused ultrasound. RESULTS: The peak pressure at focal area was improved by 140.5 ± 7.0% on target I and 134.8 ± 19.1% on target II using proposed phase correction toolkit, respectively. A total computation time of 402.1 ± 24.5 milliseconds was achieved for each sonication. CONCLUSION: The designed ray-based phase correction software can be used as a lightweight toolkit to compensate aberrated phase within clinical environment.

Optimizing Computer-Brain Interface Parameters for Non-invasive Brain-to-Brain Interface.

A non-invasive, brain-to-brain interface (BBI) requires precision neuromodulation and high temporal resolution as well as portability to increase accessibility. A BBI is a combination of the brain-computer interface (BCI) and the computer-brain interface (CBI). The optimization of BCI parameters has been extensively researched, but CBI has not. Parameters taken from the BCI and CBI literature were used to simulate a two-class medical monitoring BBI system under a wide range of conditions. BBI function was assessed using the information transfer rate (ITR), measured in bits per trial and bits per minute. The BBI ITR was a function of classifier accuracy, window update rate, system latency, stimulation failure rate (SFR), and timeout threshold. The BCI parameters, including window length, update rate, and classifier accuracy, were kept constant to investigate the effects of varying the CBI parameters, including system latency, SFR, and timeout threshold. Based on passively monitoring BCI parameters, a base ITR of 1 bit/trial was used. The optimal latency was found to be 100 ms or less, with a threshold no more than twice its value. With the optimal latency and timeout parameters, the system was able to maintain near-maximum efficiency, even with a 25% SFR. When the CBI and BCI parameters are compared, the CBI's system latency and timeout threshold should be reflected in the BCI's update rate. This would maximize the number of trials, even at a high SFR. These findings suggested that a higher number of trials per minute optimizes the ITR of a non-invasive BBI. The delays innate to each BCI protocol and CBI stimulation method must also be accounted for. The high latencies in each are the primary constraints of non-invasive BBI for the foreseeable future.

Depletion-model-based numerical simulation of the kinetics of red blood cell aggregation under sinusoidal pulsatile flow.

BACKGROUND: Previous numerical modeling studies on red blood cell (RBC) aggregation have elucidated the inverse relationship between shear rate and RBC aggregation under steady flow. However, information on the cyclic variation in RBC aggregation under pulsatile flow remains lacking. OBJECTIVE: RBC aggregation was simulated to investigate the complex interrelationships among the parameters of RBC motion under pulsatile flow. METHODS: A two-dimensional particle model was used to simulate RBC motion driven by hydrodynamic, aggregation, and elastic forces in a sinusoidal pulsatile flow field. The kinetics of RBCs motion was simulated on the basis of the depletion model. RESULTS: The simulation results corresponded with previously obtained experimental results for the formation and destruction of RBC aggregates with a parabolic radial distribution during a pulsatile cycle. In addition, the results demonstrated that the cyclic variation in the mean aggregate size of RBCs increased as velocity amplitude increased from 1 cm/s to 3 cm/s under a mean steady flow of 2 cm/s, as mean steady flow velocity decreased from 6 cm/s to 2 cm/s under a velocity amplitude of 1.5 cm/s, and as stroke rate decreased from 180 beats per minute (bpm) to 60 bpm. CONCLUSIONS: The present simulation results verified previous experimental results and improved the current understanding of the complex spatiotemporal changes experienced by RBC aggregates during a sinusoidal pulsatile cycle.

Mobility of Amphidinium carterae Hulburt measured by high-frequency ultrasound.

The over-growth of phytoplankton causes harmful algal blooms (HABs) in marine ecological environments. Mobility measurement is important in understanding the action of HABs. In this study, the mobility of Amphidinium carterae Hulburt (A. carterae) was investigated using high-frequency ultrasound in the laboratory. Mobility in response to light was illustrated with M-mode images reconstructed from echoed signals. This study suggests that mobility of the swimming speed of A. carterae in response to light can be measured and calculated with M-mode images through high-frequency ultrasound. This finding may be helpful in understanding the fundamental behavior of HABs.

Asymmetric pulsation of rat carotid artery bifurcation in three-dimension observed by ultrasound imaging.

The arterial structure cyclically fluctuates in three-dimensions (3-D) caused by pulsatile blood flow. The evaluation of arterial wall motion and hemodynamics contributes to early diagnosis of carotid atherosclerosis. Ultrasound is one of the most appropriate imaging modalities to evaluate arterial wall motion in real time. Although many previous studies have discussed the mechanical properties of the carotid artery bifurcation (CAB) from the two-dimensional (2-D) view, the spatio-temporal variation of carotid artery geometry in 3-D has not yet been investigated in detail. In this study, the 3-D data set of CAB from rats was acquired using a high spatio-temporal resolution ultrasound imaging system with a 40 MHz probe using mechanical sector scanning. A total of 31 slices of cross-section images were stored and a spoke scan algorithm was implemented to radially scan the lumen area in polar coordinates based on a pre-tracked seed point. The boundary of the arterial lumen was segmented using intensity-threshold-based boundary detection and fitted by polynomial regression. Two operators, who were trained with the same protocol to minimize inter- and intra-operator variability, manually segmented the lumen boundary on systolic and diastolic phase from the gray-scale images. Finally, the 3-D lumen geometries of CAB during one cardiac cycle were constructed based on the segmented lumen boundaries. From this constructed 3-D geometry, we observed that the CAB geometry favorably expanded to the anterior/posterior direction, parallel to the sagittal plane; and the manually segmented geometry also confirmed the asymmetrical change in bifurcation geometry. This is the first study on visualization and quantification on the asymmetrical variation of the CAB geometry of a rat in 3-D during a whole cardiac cycle. This finding may be useful in understanding hemodynamic etiology of various cardiovascular diseases such as arterial stenosis and its complications, and also provides reference information for numerical simulation studies on arterial wall motion.

Feasibility Study of Ex Ovo Chick Chorioallantoic Artery Model for Investigating Pulsatile Variation of Arterial Geometry.

Despite considerable research efforts on the relationship between arterial geometry and cardiovascular pathology, information is lacking on the pulsatile geometrical variation caused by arterial distensibility and cardiomotility because of the lack of suitable in vivo experimental models and the methodological difficulties in examining the arterial dynamics. We aimed to investigate the feasibility of using a chick embryo system as an experimental model for basic research on the pulsatile variation of arterial geometry. Optical microscope video images of various arterial shapes in chick chorioallantoic circulation were recorded from different locations and different embryo samples. The high optical transparency of the chorioallantoic membrane (CAM) allowed clear observation of tiny vessels and their movements. Systolic and diastolic changes in arterial geometry were visualized by detecting the wall boundaries from binary images. Several to hundreds of microns of wall displacement variations were recognized during a pulsatile cycle. The spatial maps of the wall motion harmonics and magnitude ratio of harmonic components were obtained by analyzing the temporal brightness variation at each pixel in sequential grayscale images using spectral analysis techniques. The local variations in the spectral characteristics of the arterial wall motion were reflected well in the analysis results. In addition, mapping the phase angle of the fundamental frequency identified the regional variations in the wall motion directivity and phase shift. Regional variations in wall motion phase angle and fundamental-to-second harmonic ratio were remarkable near the bifurcation area. In summary, wall motion in various arterial geometry including straight, curved and bifurcated shapes was well observed in the CAM artery model, and their local and cyclic variations could be characterized by Fourier and wavelet transforms of the acquired video images. The CAM artery model with the spectral analysis method is a useful in vivo experimental model for studying pulsatile variation in arterial geometry.

Low-salinity-induced surface sound channel in the western sea of Jeju Island during summer.

Surface salinity in the western sea of Jeju Island in Korea becomes low due to the inflow of the Chinese coastal waters during summer. One of the characteristics of low salinity water is the formation of a surface sound channel (SSC) due to the decrease in sound speed by salinity. However, a quantitative analysis between low salinity water and SSC has not been fully investigated yet. In this paper, a temperature-salinity (T-S) gradient diagram is introduced in order to assess SSC formation and its acoustic characteristics are also investigated through a case study of low salinity waters. Maximum angles of limiting rays were less than 4.6° and low frequency cutoffs were higher than 2.0 kHz for the SSCs formed in low salinity water. When the salinity gradients were large (>0.5 psu/m), a SSC was formed more efficiently than other cases whose salinity gradients were small. On the other hand, a SSC was not formed in spite of highly positive salinity gradients when the amount of temperature gradients was negatively high enough (<-0.5 °C/m). However, the acoustic energy transfer in the surface ducts was dependent on frequency and position of source.

Spontaneous echo-contrast in the internal jugular veins of patients with ischemic stroke.

PURPOSE: Spontaneous echo-contrast (SEC) appears on B-mode images as moving curls of smoke in the lumen of veins. The aims of this study were to investigate the prevalence and characteristics of internal jugular vein SEC among patients with stroke, in comparison with control subjects. METHODS: We enrolled 97 Korean patients with acute ischemic stroke and 50 controls. Both internal jugular veins were examined for the presence and severity of SEC and measurement of flow velocity. Venous samples were obtained for laboratory evaluation of hematologic factors. RESULTS: In 294 internal jugular veins, the prevalence of SEC was 81% in stroke patients and 68% in controls (odds ratio, 2.0; 95% confidence interval, 1.1-3.6; p = 0.013). Stroke patients were more likely to have SEC on the left (p = 0.025) than on the right (p = 0.184) internal jugular vein. Overall, the association between stroke and SEC remained significant after adjustment for other variables (odds ratio, 4.3; 95% confidence interval, 1.7-10.8; p = 0.002). CONCLUSIONS: Internal jugular vein SEC was found more frequently in stroke patients than in controls. However, local as well as systemic factors must be considered in the interpretation of this finding.

Implementation of a rotational ultrasound biomicroscopy system equipped with a high-frequency angled needle transducer--ex vivo ultrasound imaging of porcine ocular posterior tissues.

The mechanical scanning of a single element transducer has been mostly utilized for high-frequency ultrasound imaging. However, it requires space for the mechanical motion of the transducer. In this paper, a rotational scanning ultrasound biomicroscopy (UBM) system equipped with a high-frequency angled needle transducer is designed and implemented in order to minimize the space required. It was applied to ex vivo ultrasound imaging of porcine posterior ocular tissues through a minimal incision hole of 1 mm in diameter. The retina and sclera for the one eye were visualized in the relative rotating angle range of 270°~330° and at a distance range of 6~7 mm, whereas the tissues of the other eye were observed in relative angle range of 160°~220° and at a distance range of 7.5~9 mm. The layer between retina and sclera seemed to be bent because the distance between the transducer tip and the layer was varied while the transducer was rotated. Certin features of the rotation system such as the optimal scanning angle, step angle and data length need to be improved for ensure higher accuracy and precision. Moreover, the focal length should be considered for the image quality. This implementation represents the first report of a rotational scanning UBM system.