Johan C G van Hespen

University of Twente | UT · Department of Biomedical Photonic Imaging (BMPI)

Background Needle‐based procedures, such as fine needle aspiration and thermal ablation, are often applied for thyroid nodule diagnosis and therapeutic purposes, respectively. With blood vessels and nerves nearby, these procedures can pose risks in damaging surrounding critical structures. Purpose The development and validation of innovative strat...

Background: Needle-based procedures such as fine needle aspiration (FNA) and thermal ablation, are often applied for thyroid nodule diagnosis and therapeutic purposes, respectively. With blood vessels and nerves nearby, these procedures can pose risks in damaging surrounding critical structures. Purpose: The development and validation of innovative...

Photoacoustic (PA) or optoacoustic (OA) imaging combines the high (blood) contrast to light with the high-resolution of ultrasound. The method can visualize vascularization deep inside tissue. Of late there is interest in PA imaging of synovial joints which are expected to be associated with increased vascularization in the event of rheumatoid arth...

Photoacoustic (optoacoustic) imaging can visualize vasculature deep in tissue using the high contrast of hemoglobin to light, with the high-resolution possible with ultrasound detection. Since angiogenesis, one of the hallmarks of cancer, leads to increased vascularity, photoacoustics holds promise in imaging breast cancer as shown in proof-of-prin...

Photoacoustic imaging can visualize vascularization-driven optical absorption contrast with great potential for breast cancer detection and diagnosis. State-of-the-art photoacoustic breast imaging systems are promising but are limited either by only a 2D imaging capability or by an insufficient imaging field-of-view (FOV). We present a laboratory p...

Acoustic lenses made of acrylic plastic (PMMA) have been used to enlarge the acceptance angle of sensitive large surface area detectors and improve lateral resolution. However, PMMA lenses introduce image artifacts due to ultrasound internal reflections within the lenses. In this work we investigated this issue proposing a new lens material Stycast...

Purpose: Photoacoustic imaging has proven to be able to detect vascularization-driven optical absorption contrast associated with tumors. In order to detect breast tumors located a few centimeter deep in tissue, a sensitive ultrasound detector is of crucial importance for photoacoustic mammography. Further, because the expected photoacoustic frequ...

The ultrasound detector is the heart of a photoacoustic imaging system. In photoacoustic imaging of the breast there is a requirement to detect tumors located a few centimeters deep in tissue, where the light is heavily attenuated. Thus a sensitive ultrasound transducer is of crucial importance. As the frequency content of photoacoustic waves are i...

Abstract Background Angiogenesis represents a key phenomenon in psoriasis. Insights in the microcirculation within psoriatic lesions in a whole-field are lacking. Recently the Twente Optical Perfusion Camera (TOPCam) was developed, which provides the possibility of evaluating the superficial cutaneous microcirculation in a whole-field. Objectives T...

We acquired images of breast malignancies using the Twente photoacoustic mammoscope (PAM), to obtain more information about the clinical feasibility and limitations of photoacoustic mammography. Results were compared with conventional imaging and histopathology. Ten technically acceptable measurements on patients with malignancies and two measureme...

Current imaging modalities are often not able to detect early stages of breast cancer with high imaging contrast. Visualizing malignancy-associated increased hemoglobin concentrations might improve breast cancer diagnosis. Photoacoustic imaging can visualize hemoglobin in tissue with optical contrast and ultrasound resolution, which makes it potent...

A custom-made first prototype of a linear array ultrasound transducer for breast imaging is presented. Large active area transducer elements (5 mm × 5 mm) with 1 MHz resonance frequency are chosen to obtain a relatively high sensitivity. Acoustic lenses are used to enlarge the narrow acceptance angle of such transducer elements. The minimum detecta...

mammoscope is presented. Patients with highly suspicious palpable lesions are included in our clinical protocol. First results from a patient with infiltrative ductal carcinoma are presented.

p>Worldwide, yearly about 450,000 women die from the consequences of breast cancer. Current imaging modalities are not optimal in discriminating benign from malignant tissue. Visualizing the malignancy-associated increased hemoglobin concentration might significantly improve early diagnosis of breast cancer. Since photoacoustic imaging can visualiz...

A large surface area transducer is preferable to be used to detect extremely weak photoacoustic signals in mammography due to its high sensitivity. The lateral resolution is limited by the small acceptance angle of such a transducer. We introduce an excellent material for an acoustic lens used to enlarge the transducer's acceptance angle. Our acous...

We present a ‘hybrid’ imaging approach which can image both light absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography (CT) photoacoustic imager. The ultrasound transmission measurement method uses a strong optical absorber of small cross-section placed in the path of the lig...

We present latest results on phantoms and biological specimens using an intrinsically ‘hybrid’ photoacoustic imaging system. This instrument permits the tomographic imaging of both optical absorption properties and acoustic transmission properties of object.

We present a 'hybrid' imaging system, which can image both optical absorption properties and acoustic transmission properties of an object in a two-dimensional slice using a computed tomography photoacoustic imager. The ultrasound transmission measurement method uses a strong absorber of light which is placed in the path of the light illuminating t...

Photoacoustic imaging is based on detecting laser pulse induced ultrasound transients from absorbing structures in tissue. The technique combines the advantages of a high optical absorption exhibited by tumors for example with the high resolution possible with ultrasound. A conventional photoacoustic imager operating in a CT geometry comprises a li...

Near-infrared photoacoustic images of regions-of-interest in 4 of the 5 cases of patients with symptomatic breasts reveal higher intensity regions which we attribute to vascular distribution associated with cancer. Of the 2 cases presented here, one is especially significant where benign indicators dominate in conventional radiological images, whil...

Breast cancer dominates cancers in females. This burden on society and the room for improvements in the current practice of mammography have been stimuli for developing new modalities like photoacoustic mammography. At the University of Twente (UT), an instrument had been developed aimed at performing limited area scans on the human breast. This in...

The Twente Photoacoustic Mammoscope (PAM) is based on generating laser-induced ultrasound from absorbing structures in the breast. The heart of the instrument is a flat PVDF based detector matrix comprising 590 active elements. The exciting source is an Nd:YAG laser operating at 1064 nm with 5 ns pulses. The instrument is built around a hospital be...

We present PAM, the Photoacoustic Mammoscope developed at the University of Twente, intended for initial retrospective clinical studies on subjects with breast tumours. A parallel plate geometry has been adopted and the breast will be gently compressed between a glass plate and a flat ultrasound detector matrix. Pulsed light (5 ns) from an Nd:YAG l...

Performance studies of a clinical prototype for detecting tumors in the breast based on the photoacoustic effect are presented in terms of sensitivity, frequency response and resolution. Some imaging results on well characterized breast tissue phantoms with embedded tumor simulating inserts are also shown.

We present a laboratory version of a photoacoustic mammoscope, based on a parallel plate geometry. The instrument is built around a flat high-density ultrasound detector matrix. The light source is a Q-switched Nd:YAG laser with a pulse duration of 5 ns. To test the instrument, a novel photoacoustic phantom is developed using poly(vinyl alcohol) ge...

A novel photoacoustic breast phantom was developed using poly(vinyl alcohol) gel prepared by a simple technique that imparts optical scattering to the gel without the neccessity for scattering particles. Tumour simulating gel samples of suitable absorption coefficient were also prepared using a second technique, by adding appropriate quantities of...

We present a fast, computed tomography (CT) photoacoustic imager for mouse imaging. The system features a 32 element curvilinear detector and an illumination system coupled to a rotary mechanism to enable a slice to be imaged in less than 1 minute. Image reconstruction is performed using a modified acoustic backprojection algorithm. We describe the...