Yan Yan

• Doctor of Philosophy
• Senior Researcher at University of Rochester

Cervical remodeling during pregnancy is a critical process that, if untimely, can lead to complications such as preterm birth (PTB). This study introduces a novel multi-parametric approach combining non-invasive imaging modalities to quantify cervical tissue changes during pregnancy and postpartum in a murine model. By integrating ultrasound-based...

Over 250,000 gastrostomy tubes (G-tubes) are placed annually in the United States. Percutaneous endoscopic gastrostomy (PEG) is the most widely used clinical method for placing G-tubes within the stomach. However, endoscope detectability is limited due to the scattering of light by tissues. Poor organ visibility and low sensitivity of the palpation...

Synthetic transmit aperture (STA) ultrasound (US) imaging, despite its notable advantages, suffers from hardware and computational complexity leading to a high system cost, especially for an array with an excessive number of elements. Sub-array beamforming (SAB) or micro-beamforming has received attention for its ability to reduce the number of cha...

Objective To demonstrate the feasibility of using a ring array ultrasound (US) transducer, guided by ultrasound tomography (UST), for generating and monitoring mild hyperthermia (MHTh). Methods In silico and in vitro experiments were designed to evaluate the efficacy of a ring array US transducer for generating MHTh and monitoring changes in tempe...

The accuracy and efficacy of laser ablation procedures depend on the accurate placement of the laser applicator within the diseased tissue, monitoring the real-time temperature during the ablation procedure, and mapping the extent of the ablated region. Ultrasound (US) imaging has been widely used to guide ablation procedures. While US imaging offe...

Multimodal optical techniques are useful for the comprehensive characterization of material properties. In this work, we developed a new, to the best of our knowledge, multimodal technology that can simultaneously measure a subset of mechanical, optical, and acoustical properties of the sample and is based on the integration of Brillouin (Br) and p...

Purpose: Photoacoustic tomography (PAT) is a non-invasive and high-resolution imaging technique that can provide functional and molecular information from the optical properties of pathological tissues, such as cancer. Spectroscopic PAT (sPAT) is capable of supplying information such as oxygen saturation (sO2), which is an important biological ind...

Multimodal optical imaging techniques are useful for various applications, including imaging biological samples for providing comprehensive material properties. In this work, we developed a new modality that can measure a set of mechanical, optical, and acoustical properties of a sample at microscopic resolution, which is based on the integration o...

Brain shift is an important obstacle to the application of image guidance during neurosurgical interventions. There has been a growing interest in intra-operative imaging to update the image-guided surgery systems. However, due to the innate limitations of the current imaging modalities, accurate brain shift compensation continues to be a challengi...

Fetal, perinatal, and neonatal asphyxia are vital health issues for the most vulnerable groups in human beings, including fetuses, newborns, and infants. Severe reduction in oxygen and blood supply to the fetal brain can cause hypoxic-ischemic encephalopathy, leading to long-term neurological disorders, including mental impairment and cerebral pals...

Purpose: Transvaginal ultrasound (TVUS) is a widely used real-time and non-invasive imaging technique for fetal and maternal care. It can provide structural and functional measurements about the fetal brain, such as blood vessel diameter and blood flow. However, it lacks certain biochemical estimations, such as hemoglobin oxygen saturation (SO 2),...

The cervix plays a central role in pregnancy and delivery. A short cervix (≤ 25 mm), measured by ultrasound (US) imaging, at gestational ages between 22 to 24 weeks indicates a higher risk for preterm birth (PTB). Our previous publications had determined that a spectroscopic photoacoustic (sPA) imaging method in the near-infrared range has the pote...

Endovenous laser ablation (EVLA) is a minimally invasive surgical procedure, often guided by ultrasound (US) imaging, for treating venous insufficiencies. US imaging limitations in accurately visualizing the catheter and the lack of a temperature monitoring system can lead to sub-optimal outcomes. An integrated photoacoustic (PA)-guided EVLA system...

Objective: Brain shift is an importance obstacle for application of image-guidance during neurosurgical interventions. There has been a growing interest in intra-operative imaging systems to update the image-guided surgery systems with real-time data. However, due to the innate limitations of the current imaging modalities, accurate and real-time b...

Inaccurate placement of the ablation catheter and the inability to monitor the real-time temperature within the tissue of interest such as veins curbs the treatment efficacy of laser ablation procedures during thermal therapies. Our previous studies have validated the efficacy of photoacoustic (PA) imaging during endovenous laser ablation (EVLA) pr...

Objective Cervical remodeling is an important component in determining the pathway of parturition; therefore, assessing changes in cervical tissue composition may provide information about the cervix’s status beyond the measurement of cervical length. Photoacoustic imaging is a non-invasive ultrasound-based technology that captures acoustic signals...

Significance: Photoacoustic imaging (PAI) has been greatly developed in a broad range of diagnostic applications. The efficiency of light to sound conversion in PAI is limited by the ubiquitous noise arising from the tissue background, leading to a low signal-to-noise ratio (SNR), and thus a poor quality of images. Frame averaging has been widely u...

Significance: Photoacoustic imaging (PAI) has been greatly developed in a broad range of diagnostic applications. The efficiency of light to sound conversion in PAI is limited by the ubiquitous noise arising from the tissue background, leading to a low signal-to-noise ratio (SNR), and thus a poor quality of images. Frame averaging has been widely...

The next generation of intelligent robotic systems has been envisioned as micro-scale mobile and externally controllable robots. Visualization of such small size microrobots to track their motion in nontransparent medium such as human tissue remains a major challenge, limiting translation into clinical applications. Herein, we present a novel, non-...

Preterm birth (PTB) is the leading cause of neonatal morbidity and mortality worldwide. The ability to predict patients at risk for preterm birth remains a major health challenge. The currently available clinical diagnostics such as cervical length and fetal fibronectin may detect only up to 30% of patients who eventually experience a spontaneous p...

This paper presents the innovative integration of both frontier submillimeter magnetic microrobot and integrated ultrasound and photoacoustic (USPA) imaging. The integrative technique will allow for potential real non-invasive microrobot operation in deep biological tissue for biomedical applications. In this study, the magnetic microrobot prototyp...

Objectives: To develop a combined endocavity ultrasound (US) and photoacoustic (PA) imaging system (ECUPSA) for evaluation of blood perfusion and oxygenation in the fetus and neonates. Methods: The ECUSPA probe consists of a clinical transvaginal US (TVUS) transducer (operating between 5-9 MHz) with a custom-built light delivery system consisting o...

The uterine cervix plays a central role in the maintenance of pregnancy and in the process of parturition. Cervical remodeling involves dramatic changes in extracellular matrix composition and, in particular, of collagen and water content during cervical ripening (a term that describes the anatomical, biochemical, and physiologic changes in prepara...

Photoacoustic (PA) imaging is a novel ultrasound-based imaging modality which has shown tremendous diagnostic potential by providing complementary functional and molecular information. PA imaging utilizes short laser pulses to excite the tissue and probes its optical properties. Fiber guided light delivery is the most common approach for clinical P...

Visualization and detection of early-stage gynecological malignancies represents a challenge for imaging due to limiting factors including tissue accessibility, device ease of use, and accuracy of imaging modalities. In this work, we introduce a miniaturized phased-array ultrasound and photoacoustic endoscopic probe which is capable of providing st...

Background: Chorioamnionitis from ascending bacterial infection through the endocervix is a potential risk factor for cerebral palsy. Tetrahydrobiopterin, an essential cofactor for nitric oxide synthase (NOS) and amino acid hydroxylases, when augmented in the fetal brain, prevents some of the cerebral palsy-like deficits in a rabbit hypoxia-ischem...

Given that breast cancer is the second leading cause of cancer-related deaths among women in the United States, it is necessary to continue improving the sensitivity and specificity of breast imaging systems that diagnose breast lesions. Photoacoustic (PA) imaging can provide functional information during in vivo studies and can augment the structu...

Given that breast cancer is the second leading cause of cancer-related deaths among women in the United States, it is necessary to continue improving the sensitivity and specificity of breast imaging systems that diagnose breast lesions. Photoacoustic (PA) imaging can provide functional information during in vivo studies and can augment the structu...

Accurate fiber tip tracking is a critical clinical problem during endovenous laser ablation (EVLA) of small perforating veins. Currently, ultrasound (US) imaging is the gold-standard modality for visualizing and for accurately placing the ablation fiber within the diseased vein. However, US imaging has limitations such as angular dependency and com...

Photoacoustic imaging (PAI) is a promising medical imaging modality providing the spatial resolution of ultrasound (US) imaging and the contrast of optical imaging. For linear-array PAI, an image beamformer can be used as the reconstruction algorithm. Delay-and-sum (DAS) is the most prevalent beamforming algorithm in PAI. However, using DAS beamfor...

Photoacoustic imaging (PAI) is a promising medical imaging modality providing the spatial resolution of ultrasound (US) imaging and the contrast of pure optical imaging. For linear-array PAI, a beamformer has to be used as the reconstruction algorithm. Delay-and-sum (DAS) is the most prevalent beamforming algorithm in PAI. However, using DAS beamfo...

We report, for the first time, a multimodal, oxidation-responsive contrast agent for magnetic resonance imaging and photoacoustic imaging that uses the differences in the properties between Eu in the +2 and +3 oxidation states. The enhancement of contrast in T1-weighted magnetic resonance and photoacoustic imaging was observed in the +2 but not in...