Integrated diffuse optical tomography and photoacoustic tomography: phantom validations

We designed, fabricated and tested a novel imaging system that fuses diffuse optical tomography (DOT) and photoacoustic tomography (PAT) in a single platform. This platform takes advantages of both DOT and PAT, and can potentially provide dual-modality two dimensional functional and cellular images of the breast quantitatively. Here we describe this integrated platform along with initial tissue phantom validations.     

Near-field diffraction tomography

We propose an algorithm that deals with broadband ultrasonic signals acquired in the near-field domain using probes close to the skin. This technique is designed for diffraction tomography of compact support objects interrogated by spherical waves (small transducers). It is an approximate inversion procedure in the Born approximation based on elliptical backprojection. Near-field imaging is enhanced by reducing the geometrical distortion observed on standard tomography. Numerical tests based on finite difference time domain (FDTD) simulations of data scattered by a tissue-like phantom are given.     

Positron emission tomography/computed tomography of a rare xanthogranulomatous process: Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a disseminated xanthogranulomatous infiltrative disease of unknown etiology due to infiltration of different organs and bones by foamy histiocytes. A 37-year-old male with cerebral and periorbital lesions was diagnosed with this rare disease and was evaluated with magnetic resonance imaging (MRI) and 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) with positron emission tomography/computed tomography (PET/CT) imaging at baseline and following therapy. FDG-PET imaging allowed accurate evaluation of the extent of the disease at baseline, as well as assessment of response to therapy.     

Usefulness of position emission tomography/computed tomography in a case of sarcoidosis with multiorgan involvement

Sarcoidosis, a systemic inflammatory disease of unknown etiology, can affect any site in the body. A bone lesion was unexpectedly detected by fluorodeoxyglucose position emission tomography/computed tomography (FDG PET/CT) in a patient with multiorgan sarcoidosis. FDG PET/CT should be considered for the detection of clinically silent lesions of sarcoidosis.     

Speckle contrast optical tomography: A new method for deep tissue three-dimensional tomography of blood flow

A novel tomographic method based on the laser speckle contrast, speckle contrast optical tomography (SCOT) is introduced that allows us to reconstruct three dimensional distribution of blood flow in deep tissues. This method is analogous to the diffuse optical tomography (DOT) but for deep tissue blood flow. We develop a reconstruction algorithm based on first Born approximation to generate three dimensional distribution of flow using the experimental data obtained from tissue simulating phantoms.OCIS codes: (170.3880) Medical and biological imaging, (110.3010) Image reconstruction techniques, (110.6150) Speckle imaging, (110.6955) Tomographic imaging     

多排螺旋CT在神经放射的应用进展

多层螺旋CT或称多排探测器CT问世,使其数据采集更加快速,具有很高的时间和空间分辨率,以及强大的图像后处理功能,为神经放射的诊断开创了新领域,尤其是CT血管成像和脑灌注成像,具有广阔的临床应用前景.     

Potentialities of non-invasive diagnosis of coronary artery anomalies by electron-beam tomography and multislice computed tomography

AIM: To assess diagnostic value of electron-beam computed tomography and multislice computed tomography (EBT and MSCT) for diagnosis of congenital anomalies of coronary arteries (CA). MATERIAL AND METHODS: Non-invasive coronary angiography with EBT and MSCT has been performed in 1162 patients. RESULTS: Different anomalies of coronary arteries have been found in 10 (0.9%) patients. Results of EBT and MSCT agreed with those of coronary angiography performed in 8 cases with CA anomalies. Though 720 of 1162 patients had coronary stenoses, no significant atherosclerotic lesions were found in anomalous CA. CONCLUSION: EBT and MSCT enable non-invasive screening and diagnosis of coronary arteries anomalies.     

Assessment of coronary artery bypass graft patency by multidetector computed tomography and electron-beam tomography

This case report describes the use of retrospectively ECG-gated 16-slice multidetector computed tomography (MDCT) and electron-beam tomography (EBT) for assessing bypass graft patency in two patients with recurrent angina after coronary artery bypass graft surgery. The results of each tomographic modality were compared to the findings of traditional coronary angiography. In the first patient MDCT showed occlusion of the left internal mammary artery (LIMA) and saphenous vein graft after the second anastomosis. Coronary angiography confirmed these findings. In the second patient EBT showed patency of the LIMA and saphenous vein graft. After the first anastomosis of the saphenous vein graft, the connected vessel filled poorly. Coronary angiography confirmed both grafts to be patent, and detected an occlusion distal to the first anastomosis. These findings support the evidence that both MDCT and EBT are suitable techniques for establishing bypass graft patency by non-invasive means.     

From 3-D positron emission tomography to 3-D positron emission tomography/computed tomography: what did we learn?

The recent introduction of combined positron emission tomography (PET)/computed tomography (CT) scanners is having a far-reaching effect on the field of medical imaging by bringing functional imaging to the forefront in radiology, oncology and other specialties. The PET/CT scanner is an evolution in technology combining two well-developed imaging modalities: anatomical imaging with CT and functional imaging with PET. The first prototype PET/CT scanner was a consequence of a succession of steps that, in chronological order, included the development of the High Density Avalanche Chamber (HIDAC) PET camera, 3-D PET methodology and the rotating partial-ring tomograph (PRT). The successful completion of each step was a prerequisite to progress to the next phase, and the lessons learned could then be applied to subsequent initiatives. This review will map the milestones from 3-D PET to 3-D PET/CT and assess the role each step played in the development of PET instrumentation over the past two decades.     

Full-depth epidermis tomography using a Mirau-based full-field optical coherence tomography

With a Gaussian-like broadband light source from high brightness Ce³⁺:YAG single-clad crystal fiber, a full-field optical coherence tomography using a home-designed Mirau objective realized high quality images of in vivo and excised skin tissues. With a 40 × silicone-oil-immersion Mirau objective, the achieved spatial resolutions in axial and lateral directions were 0.9 and 0.51 μm, respectively. Such a high spatial resolution enables the separation of lamellar structure of the full epidermis in both the cross-sectional and en face planes. The number of layers of stratum corneum and its thickness were quantitatively measured. This label free and non-invasive optical probe could be useful for evaluating the water barrier of skin tissue in clinics. As a preliminary in vivo experiment, the blood vessel in dermis was also observed, and the flowing of the red blood cells and location of the melanocyte were traced.OCIS codes: (060.2380) Fiber optics sources and detectors, (170.4500) Optical coherence tomography, (160.1435) Biomaterials, (170.3880) Medical and biological imaging, (180.3170) Interference microscopy     

A bio-electromechanical imaging technique with combined electrical impedance and ultrasound tomography

Electrical impedance tomography (EIT) seeks to image the electrical conductivity of an object using electrical impedance measurement data at its periphery. Ultrasound reflection tomography (URT) is an imaging modality that is able to generate images of mechanical properties of the object in terms of acoustic impedance changes. Both URT and EIT have the potential to be used in various medical applications. In this paper we focus on breast tumour detection. Both URT and EIT belong to soft field tomography and suffer from the small amounts of available data and the inherently ill-posed nature of the inverse problems. These facts result in limited achievable reconstruction accuracy and resolution. A dual bio-electromechanical tomography system using ultrasound and electrical tomography is proposed in this paper to improve the detection of the small-size tumour. Data fusion techniques are implemented to combine the EIT/URT data. Based on simulations, we demonstrate the improvement of detection of small size anomalies and improved depth detection compared to single modality soft field tomography.     

Shape-parameterized diffuse optical tomography holds promise for sensitivity enhancement of fluorescence molecular tomography

A fundamental approach to enhancing the sensitivity of the fluorescence molecular tomography (FMT) is to incorporate diffuse optical tomography (DOT) to modify the light propagation modeling. However, the traditional voxel-based DOT has been involving a severely ill-posed inverse problem and cannot retrieve the optical property distributions with the acceptable quantitative accuracy and spatial resolution. Although, with the aid of an anatomical imaging modality, the structural-prior-based DOT method with either the hard- or soft-prior scheme holds promise for in vivo acquiring the optical background of tissues, the low robustness of the hard-prior scheme to the segmentation error and inferior performance of the soft-prior one in the quantitative accuracy limit its further application. We propose in this paper a shape-parameterized DOT method for not only effectively determining the regional optical properties but potentially achieving reasonable structural amelioration, lending itself to FMT for comparably improved recovery of fluorescence distribution.OCIS codes: (170.3880) Medical and biological imaging, (170.6960) Tomography, (170.3010) Image reconstruction techniques     

Standardized uptake values of normal organs on 18F-fluorodeoxyglucose positron emission tomography and computed tomography imaging

Standardized uptake values (SUVs) of normal organs were evaluated by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography and computed tomography (PET-CT) scanning. Seventy patients (38 men and 32 women) with no non-physiological 18F-FDG uptake participated in the study. All patients fasted for at least 4 h before PET-CT imaging and their fasting blood glucose levels were within the normal range. Image acquisition was performed after intravenous administration of 18F-FDG and images were obtained from the vertex to the upper thigh region. The SUVs of various organs were determined from the transverse views. The uptake of 18F-FDG was highest in the cerebrum, cerebellum, myocardium, tonsils, liver and spleen in both sexes. Having knowledge of the physiological uptake of 18F-FDG and normal organ SUVs is required for the correct interpretation of whole-body 18F-FDG-PET-CT studies.     

Multigrid-based reconstruction algorithm for quantitative photoacoustic tomography

This paper proposes a multigrid inversion framework for quantitative photoacoustic tomography reconstruction. The forward model of optical fluence distribution and the inverse problem are solved at multiple resolutions. A fixed-point iteration scheme is formulated for each resolution and used as a cost function. The simulated and experimental results for quantitative photoacoustic tomography reconstruction show that the proposed multigrid inversion can dramatically reduce the required number of iterations for the optimization process without loss of reliability in the results.OCIS codes: (170.3880) Medical and biological imaging, (170.5120) Photoacoustic imaging, (170.6960) Tomography     

Complex differential variance algorithm for optical coherence tomography angiography

We describe a complex differential variance (CDV) algorithm for optical coherence tomography based angiography. The algorithm exploits both the intensity and phase changes of optical coherence tomography (OCT) signals from flowing blood to achieve high vascular contrast, and also intrinsically reject undesirable phase signals originating from small displacement axial bulk tissue motion and instrument synchronization errors. We present this algorithm within a broader discussion of the properties of OCT signal dynamics. The performance of the algorithm is compared against two other existing algorithms using both phantom measurements and in vivo data. We show that the algorithm provides better contrast for a given number of measurements and equivalent spatial averaging.OCIS codes: (170.4500) Optical coherence tomography, (170.3010) Image reconstruction techniques     

超声断层成像用于关节置换术后影像学评估

目的 观察肌骨超声断层成像用于膝关节置换术后评估的临床价值。方法 回顾性分析10例因骨肉瘤接受膝关节置换术患者的影像学资料，记录每项检查所用时间；针对检查区域二维和三维重建图像比较各检查方法成像速度及图像质量。结果 CT、MRI及超声断层检查时间分别为(39.0±7.6)s、(332.8±48.9)s及(117.0±9.6)s, CT最快而MRI最慢。CT和MRI中的金属伪影及图像变形导致图像质量降低，影响诊断效能。超声断层成像用于观察假体周围软组织不受金属伪影影响，扫描时间较短、层面连续、图像分辨力较高，且支持三维重建，能有效评估关节假体周围软组织和积液情况，可提供更全面的软组织信息及更直观的立体图像。结论 超声断层成像可作为无创方法用于膝关节置换术后评估。     

Computed tomography of the orbit

In less than a decade computed tomography (CT scanning) had a profound impact on diagnostic radiology. Radiology of the orbit is no exception. As early as 1973, reports published in the radiological literature indicated that this new noninvasive imaging method was a highly effective way of demonstrating intraorbital mass lesions. As CT scanners became widely available, computed tomography became a significant adjunct to ophthalmological diagnosis. Today the main indications for CT scanning of the orbit are (1) suspected mass lesions, most frequently presenting as exophthalmos, (2) orbital trauma, including foreign bodies, (3) some congenital anomalies, and (4) suspicion of extension into the orbit of extraorbital disease processes. Along with ultrasonography, another new noninvasive imaging technique, CT has replaced a number of more invasive and often less effective diagnostic methods, such as orbital pneumography, venography, and arteriography as major imaging techniques in orbital pathology. The paper discusses current practices in the technique of CT scanning of the orbit including the important aspect of radiation dosimetry and the clinical applications, using a number of cases to illustrate its use.     

Use of NMR tomography in clinical practice

A new method of tomography based on nmr (nmr-tomography) was used to examine 25 normal subjects and 35 patients with tumorous, vascular, inflammatory and demyelinization processes occurring in the brain, cervical division of the spinal cord and visceral cranium. Use was made of an nmr-tomograph with a resistive magnet (magnetic field 0.14 T). It was shown that the diagnostic data of nmr-tomography correlated well with the x-ray computer-aided tomography data. In some cases, nmr-tomography provides more complete information owing to the methodological possibilities (performance of saggital tomograms) and to the basic features of the method itself (detection of tissue edema during the obtaining of hydrogen nuclei (protons) resonance. The authors describe some shortcomings of nmr-tomography, of both outfit-induced and methodological nature.     

Feature space optical coherence tomography based micro-angiography

Current optical coherence tomography (OCT) based micro-angiography is prone to noise that arises from static background. This work presents a novel feature space based optical micro-angiography (OMAG) method (fsOMAG) that can effectively differentiate flow signal from static background in the feature space. fsOMAG consists of two steps. In the first step a classification map is generated that provides criterion for classification in the second step to extract functional blood flow from experimental data set. The performance of fsOMAG is examined through phantom experiments and in-vivo human retinal imaging, and compared with the existing OMAG. The results indicate its potential for clinical applications.OCIS codes: (170.4500) Optical coherence tomography, (170.4470) Ophthalmology, (170.3880) Medical and biological imaging