Multimodal real-time imaging with laser speckle contrast and fluorescent contrast

INTRODUCTION

Laser speckle contrast imaging (LSCI) can achieve real-time 2D perfusion maps non-invasively. However, LSCI is still difficult to use in general clinical applications because of movement sensitivity and limitations in blood flow analysis. To overcome this, fluorescence imaging (FI) is combined with LSCI using a light source with a wavelength of 785 nm in near-infrared (NIR) region and validates to visualize real-time blood perfusion.

MATERIALS AND METHODS

The system was performed using Intralipid and indocyanine green (ICG) in a flow phantom that has three tubes and controlled the flow rate in 0-150 μl/min range. First, real-time LSCI was monitored and measured the change in speckle contrast by reperfusion. Then, we visualized blood perfusion of a rabbit ear under the non-invasive condition by intravenous injection using a total of five different ICG concentration solutions from 128 μM to 3.22 mM.

RESULTS

The combined system achieved the performance of processing laser speckle images at about 37-38 fps, and we simultaneously confirmed the fluorescence of ICG and changes in speckle contrast due to intralipid as a light scatterer. In addition, we obtained real-time contrast variation and fluorescent images occurring in rabbit's blood perfusion.

CONCLUSIONS

The aim of this study is to provide a real-time diagnostic imaging system that can be used in general clinical applications. LSCI and FI are combined complementary for observing tissue perfusion using a single NIR light source. The combined system could achieve real-time visualization of blood perfusion non-invasively.

Spatiotemporal tracking of gold nanorods after intranasal administration for brain targeting

Intranasal administration is becoming increasingly more attractive as a fast delivery route to the brain for therapeutics circumventing the blood-brain barrier (BBB). Gold nanorods (AuNRs) demonstrate unique optical and biological properties compared to other gold nanostructures due to their high aspect ratio. In this study, we investigated for the first time the brain region-specific distribution of AuNRs and their potential as a drug delivery platform for central nervous system (CNS) therapy following intranasal administration to mice using a battery of analytical and imaging techniques. AuNRs were functionalized with a fluorescent dye (Cyanine5, Cy5) or a metal chelator (diethylenetriaminepentaacetic dianhydride, DTPA anhydride) to complex with Indium-111 via a PEG spacer for optical and nuclear imaging, respectively. Direct quantification of gold was achieved by inductively coupled plasma mass spectrometry. Rapid AuNRs uptake in mice brains was observed within 10 min following intranasal administration which gradually reduced over time. This was confirmed by the 3 imaging/analytical techniques. Autoradiography of sagittal brain sections suggested entry to the brain via the olfactory bulb followed by diffusion to other brain regions within 1 h of administration. The presence of AuNR in glioblastoma (GBM) tumors following intranasal administration was also proven which opens doors for AuNRs applications, as nose-to-brain drug delivery carriers, for treatment of a range of CNS diseases.

Case report: multi-modality imaging of a right ventricular fibroma in a teenager

Background

Cardiac fibroma is a rare primary benign tumour of the heart. It often causes arrhythmia, endangers the lives of patients, and has a worse prognosis than other benign tumours. We report a 14-year-old female patient with a right ventricular fibroma. Various preoperative imaging examinations showed that the lesion was benign, and postoperative pathology confirmed that the lesions were fibroma.

Case summary

A 14-year-old female patient visited her doctor for more than 5 months because of a heart murmur. Echocardiography revealed a slightly hyperechoic mass in the right ventricle, and on myocardial perfusion contrast imaging, the lesion showed equal enhancement. And the lesion also showed enhancement on contrast-enhanced gated cardiac computed tomography (CT). Contrast-enhanced magnetic resonance imaging (MRI) of the heart revealed that the lesion was isointense on T₁-weighted image (T₁WI), and isointense to slightly hyperintense on T₂-weighted image (T₂WI). The lesion was significantly homogeneously enhanced on a delayed enhancement scan. A positron emission tomography-CT (PET-CT) with 18F-fluorodeoxyglucose (18F-FDG) demonstrated that the mass showed lower levels of 18F-FDG uptake. These features suggested this lesion was a benign lesion. The postoperative pathology suggested the lesion was a right ventricular fibroma. The patient was discharged 14 days after surgery and remains disease-free and asymptomatic 14 months after surgery.

Discussion

Cardiac fibromas are histologically benign, but they can cause obstruction and malignant arrhythmia. The gold standard for diagnosing fibroma is pathology. However, in the absence of pathology, it is necessary to use various imaging methods to evaluate the lesions to distinguish between benign and malignant tumours.

The way to a man's heart is through his stomach? A unique case report of transient constrictive pericarditis secondary to infarction of herniated omentum following bariatric surgery

Background

Intrapericardial diaphragmatic hernias are a rare form of diaphragmatic hernia. The presentation is usually acute due to trauma or from iatrogenic causes. In some instances however, these patients can present years later. We describe an unusual case of transient constrictive pericarditis associated with herniation of omentum through a diaphgragmatic hernia extending into the pericardial space, which infarcted following recent bariatric surgery. A multi-disciplinary approach was required with surgical correction of the diaphragmatic defect and removal of omentum from the pericardial space.

Case summary

A 38-year-old gentleman with a history of a remote abdominal stab wound and recent laparoscopic gastric sleeve procedure presented with sharp central chest pain radiating to the shoulder. Chest imaging [echocardiography, computed tomography (CT), and cardiac magnetic resonance imaging (MRI)] revealed the presence of an intrapericardial diaphragmatic hernia and herniation of devascularized omentum into the pericardial space. Surgery was undertaken to remove the pericardial omentum. Echocardiography and cardiac MRI revealed changes of pericardial constriction which resolved with anti-inflammatories.

Discussion

A multi-disciplinary approach was required in this case with surgical correction of the diaphragmatic defect and removal of omentum from the pericardial space. Multi-modal imaging proved essential in the diagnosis of this rare condition, aiding in timely diagnosis, ongoing management decisions, and for assessing therapeutic response.

Video-rate dual-modal photoacoustic and fluorescence imaging through a multimode fibre towards forward-viewing endomicroscopy

Multimode fibres (MMFs) are becoming increasingly attractive in optical endoscopy as they promise to enable unparallelled miniaturisation, spatial resolution and cost. However, high-speed imaging with wavefront shaping has been challenging. Here, we report the development of a video-rate dual-modal photoacoustic (PA) and fluorescence microscopy probe with a high-speed digital micromirror device (DMD) towards forward-viewing endomicroscopy. Optimal DMD patterns were obtained using a real-valued intensity transmission matrix algorithm to raster-scan a 1.5  μ m-diameter focused beam at the distal fibre tip for imaging. The PA imaging speed and spatial resolution were varied from  ∼ 2 to 57 frames per second and from 1.7 to 3  μ m, respectively. Further, high-fidelity PA images of carbon fibres and mouse red blood cells were acquired at unprecedented speed. The capability of dual-modal imaging was demonstrated with phantoms. We anticipate that with further miniaturisation of the ultrasound detector, this probe could be integrated into medical needles to guide minimally invasive procedures.

Acidic microenvironment responsive polymeric MOF-based nanoparticles induce immunogenic cell death for combined cancer therapy

BACKGROUND

The complex tumor microenvironment and non-targeting drugs limit the efficacy of clinical tumor therapy. For ensuring the accurate delivery and maximal effects of anticancer drugs, it is important to develop innovative drug delivery system based on nano-strategies.

RESULT

In this study, an intracellular acidity-responsive polymeric metal organic framework nanoparticle (denoted as DIMP) has been constructed, which can co-deliver the chemotherapy agent of doxorubicin (DOX) and phototherapy agent of indocyanine green (ICG) for breast carcinoma theranostics. Specifically, DIMP possesses a suitable and stable nanometer size and can respond to the acidic microenvironment in cells, thus precisely delivering drugs into target tumor sites and igniting the biological reactions towards cell apoptosis. Following in vivo and in vitro results showed that DIMP could be effectively accumulated in tumor sites and induced powerful immunogenic cell death (ICD) effect.

CONCLUSION

The designed DIMP displayed its effectiveness in combined photo-chemotherapy with auxiliary of ICD effect under a multimodal imaging monitor. Thus, the present MOF-based strategy may offer a potential paradigm for designing drug-delivery system for image-guided synergistic tumor therapy.

A general in-situ reduction method to prepare core-shell liquid-metal / metal nanoparticles for photothermally enhanced catalytic cancer therapy

Gallium indium (GaIn) alloy as a kind of liquid metal (LM) with unique chemical and physical properties has attracted increasing attention for its potential biomedical applications. Herein, a series of core-shell GaIn@Metal (Metal: Pt, Au, Ag, and Cu) heterogeneous nanoparticles (NPs) are obtained by a simple in-situ reduction method. Take core-shell GaIn@Pt NPs for example, the synthesized GaIn@Pt NPs after Pt growth on their surface showed significantly improved photothermal conversion efficiency (PCE) and thermal stability under near-infrared (NIR) II light irradiation. Moreover, the core-shell GaIn@Pt NPs also exhibited good Fenton-like catalytic effect due to the presence of Pt on their surface, and could convert tumor endogenous H₂O₂ to generate reactive oxygen species (ROS) for cancer cell killing. With biocompatible polyethylene glycol (PEG) modification, such GaIn@Pt-PEG NPs showed efficient tumor homing after intravenous injection, and could lead to effective NIR II triggered photothermal-chemodynamic synergistic therapy of tumors as evidenced in a mouse tumor model. Our work highlights the ingenious use of the chemical properties of metals, providing a rather simple route for the surface engineering of LM-based multifunctional nanoplatforms to achieve a variety of functionalities.

One-pot green synthesis of I@CNDs-Fe3O4 hybrid nanoparticles from kelp for multi-modal imaging in vivo

Multi-modal imaging technologies are playing an increasingly important role in biomedical research. However, there remains a demanding challenge to develop biocompatible contrast agents via a simple, green synthetic route for multi-modal imaging. Here we report the synthesis and applications of a new contrast agent for triple-modal imaging, that is, iodine-containing N-doping carbon nano-dots hybridized with Fe3O4 nanoparticles (I@CNDs-Fe3O4). We develop a one-pot, environment friendly hydrothermal method to synthesize the hybrid nanoparticles, primarily using kelp as the bioresource. I@CNDs-Fe3O4 nanoparticles have been demonstrated to exhibit excellent multi-modal imaging capabilities, including wavelength-tunable fluorescent imaging, X-ray attenuation for CT imaging enhancement, and T2-Weighted MR imaging. Importantly, the formulation of the hybrid nanoparticle provides an optimal solution to address the disequilibrium of osmotic pressure caused by the conventional CT imaging contrast agents of iodine compounds. The I@CNDs-Fe3O4 nanoparticles promise important applications in multi-modal imaging technologies in vivo as a versatile and biocompatible contrast agent.

Image Integration Procedures in Multisensory Medical Images: A Comprehensive Survey of the state-of-the-art Paradigms

BACKGROUND

Obtaining the medical history from a patient is a tedious task for doctors as it depends on a lot of factors which are difficult to keep track from a patient's perspective. Doctors have to rely upon the technological tools to make a swift and accurate judgment about the patient's health.

INTRODUCTION

Out of many such tools, there are two special imaging modalities known as X-ray - Computed Tomography (CT) and Magnetic Resonance imaging (MRI) which are of a significant importance in the medical world assisting the diagnosis process.

METHOD

The advancement in signal processing theory and analysis has led to design and implementation of large number of image processing and fusion algorithms. Each of these methods have evolved in terms in their terms of their computational efficiency and visual results over the years.

RESULT

Various researches have revealed their properties in terms of their efficiency and outreach and it has been concluded that image fusion can be very suitable process that can help to compensate the drawbacks.

CONCLUSION

In this manuscript, recent state-of-the-art techniques have been used to fuse these image modalities and established its need and importance in a more intuitive way with the help of a wide range of assessment parameters.

Multi-modal imaging of high-risk ductal carcinoma in situ of the breast using C2Am: a targeted cell death imaging agent

BACKGROUND

Ductal carcinoma in situ (DCIS) is a non-invasive form of early breast cancer, with a poorly understood natural history of invasive transformation. Necrosis is a well-recognized adverse prognostic feature of DCIS, and non-invasive detection of its presence and spatial extent could provide information not obtainable by biopsy. We describe here imaging of the distribution and extent of comedo-type necrosis in a model of human DCIS using C2Am, an imaging agent that binds to the phosphatidylserine exposed by necrotic cells.

METHODS

We used an established xenograft model of human DCIS that mimics the histopathological features of the disease. Planar near-infrared and optoacoustic imaging, using fluorescently labeled C2Am, were used to image non-invasively the presence and extent of lesion necrosis.

RESULTS

C2Am showed specific and sensitive binding to necrotic areas in DCIS tissue, detectable both in vivo and ex vivo. The imaging signal generated in vivo using near-infrared (NIR) fluorescence imaging was up to 6-fold higher in DCIS lesions than in surrounding fat pad or skin tissue. There was a correlation between the C2Am NIR fluorescence (Pearson R = 0.783, P = 0.0125) and optoacoustic signals (R > 0.875, P < 0.022) in the DCIS lesions in vivo and the corresponding levels of cell death detected histologically.

CONCLUSIONS

C2Am is a targeted multi-modal imaging agent that could complement current anatomical imaging methods for detecting DCIS. Imaging the presence and spatial extent of necrosis may give better prognostic information than that obtained by biopsy alone.

50 Shades of CLEM: How to choose the right approach for you

Correlative light and electron microscopy (CLEM) combines the strengths of light microscopy (LM) and electron microscopy (EM) to pin-point and visualize cellular or macromolecular structures. However, there are many different imaging modalities that can be combined in a CLEM workflow, creating a vast number of combinations that can overwhelm new-comers to the field. Here, we offer a conceptual framework to help guide the decision-making process for choosing the CLEM workflow that can best address your research question, based on the answer to five questions.

Biodegradable hollow mesoporous organosilica nanotheranostics (HMON) for multi-mode imaging and mild photo-therapeutic-induced mitochondrial damage on gastric cancer

Background

CuS-modified hollow mesoporous organosilica nanoparticles (HMON@CuS) have been preferred as non-invasive treatment for cancer, as near infrared (NIR)-induced photo-thermal effect (PTT) and/or photo-dynamic effect (PDT) could increase cancer cells’ apoptosis. However, the certain role of HMON@CuS-produced-PTT&PDT inducing gastric cancer (GC) cells’ mitochondrial damage, remained unclear. Moreover, theranostic efficiency of HMON@CuS might be well improved by applying multi-modal imaging, which could offer an optimal therapeutic region and time window. Herein, new nanotheranostics agents were reported by Gd doped HMON decorated by CuS nanocrystals (called HMON@CuS/Gd).

Results

HMON@CuS/Gd exhibited appropriate size distribution, good biocompatibility, l-Glutathione (GSH) responsive degradable properties, high photo-thermal conversion efficiency (82.4%) and a simultaneous reactive oxygen species (ROS) generation effect. Meanwhile, HMON@CuS/Gd could efficiently enter GC cells, induce combined mild PTT (43–45 °C) and PDT under mild NIR power density (0.8 W/cm²). Surprisingly, it was found that PTT might not be the only factor of cell apoptosis, as ROS induced by PDT also seemed playing an essential role. The NIR-induced ROS could attack mitochondrial transmembrane potentials (MTPs), then promote mitochondrial reactive oxygen species (mitoROS) production. Meanwhile, mitochondrial damage dramatically changed the expression of anti-apoptotic protein (Bcl-2) and pro-apoptotic protein (Bax). Since that, mitochondrial permeability transition pore (mPTP) was opened, followed by inducing more cytochrome c (Cyto C) releasing from mitochondria into cytosol, and finally activated caspase-9/caspase-3-depended cell apoptosis pathway. Our in vivo data also showed that HMON@CuS/Gd exhibited good fluorescence (FL) imaging (wrapping fluorescent agent), enhanced T1 imaging under magnetic resonance imaging (MRI) and infrared thermal (IRT) imaging capacities. Guided by FL/MRI/IRT trimodal imaging, HMON@CuS/Gd could selectively cause mild photo-therapy at cancer region, efficiently inhibit the growth of GC cells without evident systemic toxicity in vivo.

Conclusion

HMON@CuS/Gd could serve as a promising multifunctional nanotheranostic platform and as a cancer photo-therapy agent through inducing mitochondrial dysfunction on GC.

Observation and characterisation of macrophages in zebrafish liver

Kupffer cells are liver-resident macrophages that play an important role in mediating immune-related functions in mammals and humans. They are well-known for their capacity to phagocytose large amounts of waste complexes, cell debris, microbial particles and even malignant cells. Location, appearance and functional aspects are important features used to identify these characteristic cells of the liver sinusoid. To-date, there is limited information on the occurrence of macrophages in zebrafish liver. Therefore, we aimed to characterise the ultrastructural and functional aspects of liver-associated macrophages in the zebrafish model by taking advantage of the latest advances in zebrafish genetics and multimodal correlative imaging. Herein, we report on the occurrence of macrophages within the zebrafish liver exhibiting conventional ultrastructural features (e.g. presence of pseudopodia, extensive lysosomal apparatus, a phagolysosome and making up ∼3% of the liver volume). Intriguingly, these cells were not located within the sinusoidal vascular bed of hepatic tissue but instead resided between hepatocytes and lacked phagocytic function. While our results demonstrated the presence and structural similarities with liver macrophages from other experimental models, their functional characteristics were distinctly different from Kupffer cells that have been described in rodents and humans. These findings illustrate that the innate immune system of the zebrafish liver has some distinctly different characteristics compared to other animal experimental models. This conclusion underpins our call for future studies in order to have a better understanding of the physiological role of macrophages residing between the parenchymal cells of the zebrafish liver.

Minimally invasive photoacoustic imaging: Current status and future perspectives

Photoacoustic imaging (PAI) is an emerging biomedical imaging modality that is based on optical absorption contrast, capable of revealing distinct spectroscopic signatures of tissue at high spatial resolution and large imaging depths. However, clinical applications of conventional non-invasive PAI systems have been restricted to examinations of tissues at depths less than a few cm due to strong light attenuation. Minimally invasive photoacoustic imaging (miPAI) has greatly extended the landscape of PAI by delivering excitation light within tissue through miniature fibre-optic probes. In the past decade, various miPAI systems have been developed with demonstrated applicability in several clinical fields. In this article, we present an overview of the current status of miPAI and our thoughts on future perspectives.

Intercostal artery pseudoaneurysm following thoracentesis: multi-modal imaging and treatment

Background

A pseudoaneurysm occurs as the result of a contained rupture of an arterial wall, yielding a perfused sac that communicates with the arterial lumen. Pseudoaneurysm of an intercostal artery is an extremely rare event but it carries with it a significant risk of rupture and subsequent hemothorax. It must be considered as a potential complication of thoracentesis.

Case presentation

Here, we report a rare case of an intercostal artery pseudoaneurysm following thoracentesis in an 82-year old male. The patient presented with respiratory distress 1 day after a therapeutic thoracentesis had been performed. Computed tomography (CT) with contrast revealed a left intercostal pseudoaneurysm with hemothorax and adjacent compressive atelectasis. Doppler ultrasound revealed bidirectional blood flow in the pseudoaneurysm sac. An intercostal arteriogram and thoracic aortogram aided in confirmation of the pseudoaneurysm and successful treatment with coil embolization.

Conclusions

An intercostal pseudoaneurysm complication following thoracentesis is very rare but important to rule out as a possible cause of hemothorax after the procedure. Capturing this finding with the aid of multiple imaging modalities allowed for diagnostic certainty and rapid treatment with coil embolization, leading to a successful patient recovery.

Multi-modal synergistic PET and MR reconstruction using mutually weighted quadratic priors

PURPOSE

To propose a framework for synergistic reconstruction of PET-MR and multi-contrast MR data to improve the image quality obtained from noisy PET data and from undersampled MR data.

THEORY AND METHODS

Weighted quadratic priors were devised to preserve common boundaries between PET-MR images while reducing noise, PET Gibbs ringing, and MR undersampling artifacts. These priors are iteratively reweighted using normalized multi-modal Gaussian similarity kernels. Synergistic PET-MR reconstructions were built on the PET maximum a posteriori expectation maximization algorithm and the MR regularized sensitivity encoding method. The proposed approach was compared to conventional methods, total variation, and prior-image weighted quadratic regularization methods. Comparisons were performed on a simulated [18 F]fluorodeoxyglucose-PET and T1 /T2 -weighted MR brain phantom, 2 in vivo T1 /T2 -weighted MR brain datasets, and an in vivo [18 F]fluorodeoxyglucose-PET and fluid-attenuated inversion recovery/T1 -weighted MR brain dataset.

RESULTS

Simulations showed that synergistic reconstructions achieve the lowest quantification errors for all image modalities compared to conventional, total variation, and weighted quadratic methods. Whereas total variation regularization preserved modality-unique features, this method failed to recover PET details and was not able to reduce MR artifacts compared to our proposed method. For in vivo MR data, our method maintained similar image quality for 3× and 14× accelerated data. Reconstruction of the PET-MR dataset also demonstrated improved performance of our method compared to the conventional independent methods in terms of reduced Gibbs and undersampling artifacts.

CONCLUSION

The proposed methodology offers a robust multi-modal synergistic image reconstruction framework that can be readily built on existing established algorithms.

Non-invasive imaging reveals conditions that impact distribution and persistence of cells after in vivo administration

Background

Cell-based regenerative medicine therapies are now frequently tested in clinical trials. In many conditions, cell therapies are administered systemically, but there is little understanding of their fate, and adverse events are often under-reported. Currently, it is only possible to assess safety and fate of cell therapies in preclinical studies, specifically by monitoring animals longitudinally using multi-modal imaging approaches. Here, using a suite of in vivo imaging modalities to explore the fate of a range of human and murine cells, we investigate how route of administration, cell type and host immune status affect the fate of administered cells.

Methods

We applied a unique imaging platform combining bioluminescence, optoacoustic and magnetic resonance imaging modalities to assess the safety of different human and murine cell types by following their biodistribution and persistence in mice following administration into the venous or arterial system.

Results

Longitudinal imaging analyses (i) suggested that the intra-arterial route may be more hazardous than intravenous administration for certain cell types, (ii) revealed that the potential of a mouse mesenchymal stem/stromal cell (MSC) line to form tumours depended on administration route and mouse strain and (iii) indicated that clinically tested human umbilical cord (hUC)-derived MSCs can transiently and unexpectedly proliferate when administered intravenously to mice.

Conclusions

In order to perform an adequate safety assessment of potential cell-based therapies, a thorough understanding of cell biodistribution and fate post administration is required. The non-invasive imaging platform used here can expose not only the general organ distribution of these therapies, but also a detailed view of their presence within different organs and, importantly, tumourigenic potential. Our observation that the hUC-MSCs but not the human bone marrow (hBM)-derived MSCs persisted for a period in some animals suggests that therapies with these cells should proceed with caution.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1076-x) contains supplementary material, which is available to authorized users.

Classification of the glioma grading using radiomics analysis

Background

Grading of gliomas is critical information related to prognosis and survival. We aimed to apply a radiomics approach using various machine learning classifiers to determine the glioma grading.

Methods

We considered 285 (high grade n = 210, low grade n = 75) cases obtained from the Brain Tumor Segmentation 2017 Challenge. Manual annotations of enhancing tumors, non-enhancing tumors, necrosis, and edema were provided by the database. Each case was multi-modal with T1-weighted, T1-contrast enhanced, T2-weighted, and FLAIR images. A five-fold cross validation was adopted to separate the training and test data. A total of 468 radiomics features were calculated for three types of regions of interest. The minimum redundancy maximum relevance algorithm was used to select features useful for classifying glioma grades in the training cohort. The selected features were used to build three classifier models of logistics, support vector machines, and random forest classifiers. The classification performance of the models was measured in the training cohort using accuracy, sensitivity, specificity, and area under the curve (AUC) of the receiver operating characteristic curve. The trained classifier models were applied to the test cohort.

Results

Five significant features were selected for the machine learning classifiers and the three classifiers showed an average AUC of 0.9400 for training cohorts and 0.9030 (logistic regression 0.9010, support vector machine 0.8866, and random forest 0.9213) for test cohorts.

Discussion

Glioma grading could be accurately determined using machine learning and feature selection techniques in conjunction with a radiomics approach. The results of our study might contribute to high-throughput computer aided diagnosis system for gliomas.

Iron oxide-carbon core-shell nanoparticles for dual-modal imaging-guided photothermal therapy

Nanostructured materials that have low tissue toxicity, multi-modal imaging capability and high photothermal conversion efficiency have great potential to enable image-guided near infrared (NIR) photothermal therapy (PTT). Here, we report a bifunctional nanoparticle (BFNP, ∼16 nm) comprised of a magnetic Fe3O4 core (∼9.1 nm) covered by a fluorescent carbon shell (∼3.4 nm) and prepared via a one-pot solvothermal synthesis method using ferrocene as the sole source. The BFNP exhibits excitation wavelength-tunable, upconverted and near-infrared (NIR) fluorescence property due to the presence of the carbon shell, and superparamagnetic behavior resulted from the Fe3O4 core. BFNPs demonstrate dual-modal imaging capacity both in vitro and in vivo with fluorescent imaging excited under a varying wavelength from 405 nm to 820 nm and with T2-weighted magnetic resonance imaging (r2 = 264.76 mM-1 s-1). More significantly, BFNPs absorb and convert NIR light to heat enabling photothermal therapy as demonstrated mice bearing C6 glioblastoma. These BFNPs show promise as an advanced nanoplatform to provide imaging guided photothermal therapy.

PET/MRI: a frontier in era of complementary hybrid imaging

With primitive approaches, the diagnosis and therapy were operated at the cellular, molecular, or even at the genetic level. As the diagnostic techniques are more concentrated towards molecular level, multi modal imaging becomes specifically essential. Multi-modal imaging has extensive applications in clinical as well as in pre-clinical studies. Positron Emission Tomography (PET) has flourished in the field of nuclear medicine, which has motivated it to fuse with Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) for PET/CT and PET/MRI respectively. However, the challenges in PET/CT are due to the inability of simultaneous acquisition and reduced soft tissue contrast, which has led to the development of PET/MRI. Also, MRI offers the better soft tissue contrast over CT. Hence, fusion of PET and MRI results in combining structural information with functional image from PET. Yet, it has many technical challenges due to the interference between the modalities. Also, it must be resolved with various approaches for addressing the shortcomings of each system and improvise on the image quantification system. This review elaborates on the various challenges in the present PET/MRI system and the future directions of the hybrid modality. Also, the different data acquisition and analysis techniques of PET/MRI system are discussed with enhanced details on the software tools.

The spatiotemporal pattern of pure tone processing: A single-trial EEG-fMRI study

Although considerable research has been published on pure tone processing, its spatiotemporal pattern is not well understood. Specifically, the link between neural activity in the auditory pathway measured by functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) markers of pure tone processing in the P1, N1, P2, and N4 components is not well established. In this study, we used single-trial EEG-fMRI as a multi-modal fusion approach to integrate concurrently acquired EEG and fMRI data, in order to understand the spatial and temporal aspects of the pure tone processing pathway. Data were recorded from 33 subjects who were presented with stochastically alternating pure tone sequences with two different frequencies: 200 and 6400 Hz. Brain network correlated with trial-to-trial variability of the task-discriminating EEG amplitude was identified. We found that neural responses responding to pure tone perception are spatially along the auditory pathway and temporally divided into three stages: (1) the early stage (P1), wherein activation occurs in the midbrain, which constitutes a part of the low level auditory pathway; (2) the middle stage (N1, P2), wherein correlates were found in areas associated with the posterodorsal auditory pathway, including the primary auditory cortex and the motor cortex; (3) the late stage (N4), wherein correlation was found in the motor cortex. This indicates that trial-by-trial variation in neural activity in the P1, N1, P2, and N4 components reflects the sequential engagement of low- and high-level parts of the auditory pathway for pure tone processing. Our results demonstrate that during simple pure tone listening tasks, regions associated with the auditory pathway transiently correlate with trial-to-trial variability of the EEG amplitude, and they do so on a millisecond timescale with a distinct temporal ordering.

Efficacy of rituximab in non-paraneoplastic autoimmune retinopathy

Background

Autoimmune retinopathy (AIR) is a rare but potentially blinding condition that is often underdiagnosed. Common features in AIR presentation include rapidly progressive vision loss with abnormal electrophysiological responses of the retina associated with positive anti-retinal antibodies. AIR is also challenging to treat, and thus, the introduction of new potential therapeutic agents is welcomed. The goal of this communication is to assess the effects of rituximab infusions on electroretinogram (ERG) responses and visual function outcomes in patients with non-paraneoplastic autoimmune retinopathy (npAIR).

Results

Following infusion(s), three out of five patients showed no evidence of disease progression or improved, while two patients continued to progress on ERG. One patient demonstrated improvement in visual acuity (2 lines) in both eyes. ERG responses provided objective monitoring of patients’ visual function and response to immunosuppression over time.

Conclusions

These findings suggest that patients with npAIR unresponsive to other immunosuppression therapies may benefit from rituximab infusion, although stabilization rather than improvement was more frequently the outcome in our case series. Furthermore, regularly scheduled ERG follow-up examinations are recommended for monitoring patients’ progression during treatment.

Cross contrast multi-channel image registration using image synthesis for MR brain images

Multi-modal deformable registration is important for many medical image analysis tasks such as atlas alignment, image fusion, and distortion correction. Whereas a conventional method would register images with different modalities using modality independent features or information theoretic metrics such as mutual information, this paper presents a new framework that addresses the problem using a two-channel registration algorithm capable of using mono-modal similarity measures such as sum of squared differences or cross-correlation. To make it possible to use these same-modality measures, image synthesis is used to create proxy images for the opposite modality as well as intensity-normalized images from each of the two available images. The new deformable registration framework was evaluated by performing intra-subject deformation recovery, intra-subject boundary alignment, and inter-subject label transfer experiments using multi-contrast magnetic resonance brain imaging data. Three different multi-channel registration algorithms were evaluated, revealing that the framework is robust to the multi-channel deformable registration algorithm that is used. With a single exception, all results demonstrated improvements when compared against single channel registrations using the same algorithm with mutual information.

Long-term outcomes of myopic choroidal neovascularisation treated with combined ranibizumab and dexamethasone characterised by multi-modal imaging

AIM

To characterise the long-term outcomes of myopic choroidal neovascularisation (mCNV) treated with combined ranibizumab and dexamethasone, with the use of multi-modal imaging.

METHODS

A retrospective study of 20 eyes with mCNV treated with intra-vitreal ranibizumab and dexamethasone on a treat-as-needed basis were followed up for a mean period of 47 months (range 19-81 months).

RESULTS

The mean age was 55 ± 16 years, with mean refractive error of -9.0 diopters. Subfoveal mCNV was seen in 11 eyes (52 %) and the others were juxtafoveal. At the final visit, 13 patients (65 %) had improvement, while four patients (20 %) had worsening in vision. The average number of ranibizumab and dexamethasone injections required was 3 ± 1.7. There was a significant improvement in the mean visual acuity, reduction of the central retinal thickness, and an enlargement of the area of chorioretinal atrophy. The mean rate of increase in chorioretinal atrophy area was 0.05 ± 0.09 mm²/month. Disruption of the photoreceptor layer, fragmentation of the retinal pigment epithelium, and breaks in the Bruch's membrane with a hyper-reflective lesion causing separation of the outer retinal layers were changes associated with active mCNV seen on optical coherence tomography (OCT).

CONCLUSION

Visual outcomes of mCNV treated with ranibizumab and dexamethasone on a treat-as-needed basis have favourable visual acuity outcomes. Using multi-modal imaging to monitor treatment response, chorioretinal atrophy, which may be related to visual function, should be used as an additional outcome measure to study the effect of combination treatment versus monotherapy.

Imaging Neurodegeneration: Steps Toward Brain Network-Based Pathophysiology and Its Potential for Multi-modal Imaging Diagnostics

PURPOSE

Multi-modal brain imaging provides different in vivo windows into the human brain and thereby different ways to characterize brain disorders. Particularly, resting-state functional magnetic resonance imaging facilitates the study of macroscopic intrinsic brain networks, which are critical for development and spread of neurodegenerative processes in different neurodegenerative diseases. The aim of the current study is to present and highlight some paradigmatic findings in intrinsic network-based pathophysiology of neurodegenerative diseases and its potential for new network-based multimodal tools in imaging diagnostics.

METHODS

Qualitative review of selected multi-modal imaging studies in neurodegenerative diseases particularly in Alzheimer's disease (AD).

RESULTS

Functional connectivity of intrinsic brain networks is selectively and progressively impaired in AD, with changes likely starting before the onset of symptoms in fronto-parietal key networks such as default mode or attention networks. Patterns of distribution and development of both amyloid-β plaques and atrophy are linked with network connectivity changes, suggesting that start and spread of pathology interacts with network connectivity. Qualitatively similar findings have been observed in other neurodegenerative disorders, suggesting shared mechanisms of network-based pathophysiology across diseases.

CONCLUSION

Spread of neurodegeneration is intimately linked with the functional connectivity of intrinsic brain networks. These pathophysiological insights pave the way for new multi-modal network-based tools to detect and characterize neurodegeneration in individual patients.

An efficient nano-based theranostic system for multi-modal imaging-guided photothermal sterilization in gastrointestinal tract

Since understanding the healthy status of gastrointestinal tract (GI tract) is of vital importance, clinical implementation for GI tract-related disease have attracted much more attention along with the rapid development of modern medicine. Here, a multifunctional theranostic system combining X-rays/CT/photothermal/photoacoustic mapping of GI tract and imaging-guided photothermal anti-bacterial treatment is designed and constructed. PEGylated W18O49 nanosheets (PEG-W18O49) are created via a facile solvothermal method and an in situ probe-sonication approach. In terms of excellent colloidal stability, low cytotoxicity, and neglectable hemolysis of PEG-W18O49, we demonstrate the first example of high-performance four-modal imaging of GI tract by using these nanosheets as contrast agents. More importantly, due to their intrinsic absorption of NIR light, glutaraldehyde-modified PEG-W18O49 are successfully applied as fault-free targeted photothermal agents for imaging-guided killing of bacteria on a mouse infection model. Critical to pre-clinical and clinical prospects, long-term toxicity is further investigated after oral administration of these theranostic agents. These kinds of tungsten-based nanomaterials exhibit great potential as multi-modal contrast agents for directed visualization of GI tract and anti-bacterial agents for phothothermal sterilization.

Interactive Feature Space Explorer© for multi-modal magnetic resonance imaging

Wider information content of multi-modal biomedical imaging is advantageous for detection, diagnosis and prognosis of various pathologies. However, the necessity to evaluate a large number images might hinder these advantages and reduce the efficiency. Herein, a new computer aided approach based on the utilization of feature space (FS) with reduced reliance on multiple image evaluations is proposed for research and routine clinical use. The method introduces the physician experience into the discovery process of FS biomarkers for addressing biological complexity, e.g., disease heterogeneity. This, in turn, elucidates relevant biophysical information which would not be available when automated algorithms are utilized. Accordingly, the prototype platform was designed and built for interactively investigating the features and their corresponding anatomic loci in order to identify pathologic FS regions. While the platform might be potentially beneficial in decision support generally and specifically for evaluating outlier cases, it is also potentially suitable for accurate ground truth determination in FS for algorithm development. Initial assessments conducted on two different pathologies from two different institutions provided valuable biophysical perspective. Investigations of the prostate magnetic resonance imaging data resulted in locating a potential aggressiveness biomarker in prostate cancer. Preliminary findings on renal cell carcinoma imaging data demonstrated potential for characterization of disease subtypes in the FS.

Classification algorithms with multi-modal data fusion could accurately distinguish neuromyelitis optica from multiple sclerosis

Neuromyelitis optica (NMO) exhibits substantial similarities to multiple sclerosis (MS) in clinical manifestations and imaging results and has long been considered a variant of MS. With the advent of a specific biomarker in NMO, known as anti-aquaporin 4, this assumption has changed; however, the differential diagnosis remains challenging and it is still not clear whether a combination of neuroimaging and clinical data could be used to aid clinical decision-making. Computer-aided diagnosis is a rapidly evolving process that holds great promise to facilitate objective differential diagnoses of disorders that show similar presentations. In this study, we aimed to use a powerful method for multi-modal data fusion, known as a multi-kernel learning and performed automatic diagnosis of subjects. We included 30 patients with NMO, 25 patients with MS and 35 healthy volunteers and performed multi-modal imaging with T1-weighted high resolution scans, diffusion tensor imaging (DTI) and resting-state functional MRI (fMRI). In addition, subjects underwent clinical examinations and cognitive assessments. We included 18 a priori predictors from neuroimaging, clinical and cognitive measures in the initial model. We used 10-fold cross-validation to learn the importance of each modality, train and finally test the model performance. The mean accuracy in differentiating between MS and NMO was 88%, where visible white matter lesion load, normal appearing white matter (DTI) and functional connectivity had the most important contributions to the final classification. In a multi-class classification problem we distinguished between all of 3 groups (MS, NMO and healthy controls) with an average accuracy of 84%. In this classification, visible white matter lesion load, functional connectivity, and cognitive scores were the 3 most important modalities. Our work provides preliminary evidence that computational tools can be used to help make an objective differential diagnosis of NMO and MS.

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We developed models for automatic differential diagnosis between multiple sclerosis and neuromyelitis optica.

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Multimodal imaging may be integrated with clinical and cognitive data to develop multidimensional classification algorithms.

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Classification algorithms could be used to aid in objective clinical decision making.

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Future research should assess the generalizability of classification algorithms in independent cohorts.

Simultaneous EEG-fMRI reveals a temporal cascade of task-related and default-mode activations during a simple target detection task

Focused attention continuously and inevitably fluctuates, and to completely understand the mechanisms responsible for these modulations it is necessary to localize the brain regions involved. During a simple visual oddball task, neural responses measured by electroencephalography (EEG) modulate primarily with attention, but source localization of the correlates is a challenge. In this study we use single-trial analysis of simultaneously-acquired scalp EEG and functional magnetic resonance image (fMRI) data to investigate the blood oxygen level dependent (BOLD) correlates of modulations in task-related attention, and we unravel the temporal cascade of these transient activations. We hypothesize that activity in brain regions associated with various task-related cognitive processes modulates with attention, and that their involvements occur transiently in a specific order. We analyze the fMRI BOLD signal by first regressing out the variance linked to observed stimulus and behavioral events. We then correlate the residual variance with the trial-to-trial variation of EEG discriminating components for identical stimuli, estimated at a sequence of times during a trial. Post-stimulus and early in the trial, we find activations in right-lateralized frontal regions and lateral occipital cortex, areas that are often linked to task-dependent processes, such as attentional orienting, and decision certainty. After the behavioral response we see correlates in areas often associated with the default-mode network and introspective processing, including precuneus, angular gyri, and posterior cingulate cortex. Our results demonstrate that during simple tasks both task-dependent and default-mode networks are transiently engaged, with a distinct temporal ordering and millisecond timescale.

Viewpoints on Medical Image Processing: From Science to Application

Medical image processing provides core innovation for medical imaging. This paper is focused on recent developments from science to applications analyzing the past fifteen years of history of the proceedings of the German annual meeting on medical image processing (BVM). Furthermore, some members of the program committee present their personal points of views: (i) multi-modality for imaging and diagnosis, (ii) analysis of diffusion-weighted imaging, (iii) model-based image analysis, (iv) registration of section images, (v) from images to information in digital endoscopy, and (vi) virtual reality and robotics. Medical imaging and medical image computing is seen as field of rapid development with clear trends to integrated applications in diagnostics, treatment planning and treatment.

Functional imaging and endoscopy

The emergence of endoscopy for the diagnosis of gastrointestinal diseases and the treatment of gastrointestinal diseases has brought great changes. The mere observation of anatomy with the imaging mode using modern endoscopy has played a significant role in this regard. However, increasing numbers of endoscopies have exposed additional deficiencies and defects such as anatomically similar diseases. Endoscopy can be used to examine lesions that are difficult to identify and diagnose. Early disease detection requires that substantive changes in biological function should be observed, but in the absence of marked morphological changes, endoscopic detection and diagnosis are difficult. Disease detection requires not only anatomic but also functional imaging to achieve a comprehensive interpretation and understanding. Therefore, we must ask if endoscopic examination can be integrated with both anatomic imaging and functional imaging. In recent years, as molecular biology and medical imaging technology have further developed, more functional imaging methods have emerged. This paper is a review of the literature related to endoscopic optical imaging methods in the hopes of initiating integration of functional imaging and anatomical imaging to yield a new and more effective type of endoscopy.