Concordance between vessel-specific and vascular territory coronary functional assessment: A comparison of quantitative flow ratio and myocardial perfusion scintigraphy

BACKGROUND

Quantitative flow ratio (QFR) and myocardial perfusion scintigraphy (MPS) are utilized for assessing coronary artery disease (CAD) significance. We aimed to analyze their concordance and prognostic impact.

AIMS

We aimed to analyze the concordance between QFR and MPS and their risk stratification.

METHODS

Patients with invasive coronary angiography and MPS were categorized as concordant if QFR ≤ 0.80 and summed difference score (SDS) ≥ 4 or if QFR > 0.80 and SDS < 4; otherwise, they were discordant. Concordance was classified by coronary territory involvement: total (three territories), partial (two territories), poor (one territory), and total discordance (zero territories). Leaman score assessed coronary atherosclerotic burden.

RESULTS

2010 coronary territories (670 patients) underwent joint QFR and MPS analysis. MPS area under the curve for QFR ≤ 0.80 was 0.637. Concordance rates were total (52.5%), partial (29.1%), poor (15.8%), and total discordance (2.6%). Most concordance occurred in patients without significant CAD or with single-vessel disease (89.5%), particularly without MPS perfusion defects (91.5%). Leaman score (odds ratio [OR]: 0.839, 95% confidence interval [CI]: 0.805-0.875, p < 0.001) and MPS perfusion defect (summed stress score [SSS] ≥ 4) (OR: 0.355, 95% CI: 0.211-0.596, p < 0.001) were independent predictors for discordance. After 1400 days, no significant difference in death/myocardial infarction was observed based on MPS assessment, but Leaman score, functional Leaman score, and average QFR identified higher risk patients.

CONCLUSIONS

MPS showed good overall accuracy in assessing QFR significance but substantial discordance existed. Predictors for discordance included higher atherosclerotic burden and MPS perfusion defects (SSS ≥ 4). Leaman score, QFR-based functional Leaman score, and average QFR provided better risk stratification for all-cause death and myocardial infarction than MPS.

Visualization of intradermal blood vessel structures by dual-wavelength photoacoustic microscopy and characterization of three-dimensional construction of livedo-racemosa in cutaneous polyarteritis nodosa

BACKGROUND

Photoacoustic microscopy is expected to have clinical applications as a noninvasive and three-dimensional (3D) method of observing intradermal structures.

OBJECTIVE

Investigate the applicability of a photoacoustic microscope equipped with two types of pulsed lasers that can simultaneously recognize hemoglobin and melanin.

METHODS

16 skin lesions including erythema, pigmented lesions, vitiligo and purpura, were analyzed to visualize 3D structure of melanin granule distribution and dermal blood vessels. 13 cases of livedo racemosa in cutaneous polyarteritis nodosa (cPN) were further analyzed to visualize the 3D structure of dermal blood vessels in detail. Vascular structure was also analyzed in the biopsy specimens obtained from tender indurated erythema of cPN by CD34 immunostaining.

RESULTS

Hemoglobin-recognition signal clearly visualized the 3D structure of dermal blood vessels and melanin-recognition signal was consistently reduced in vitiligo. In livedo racemosa, the hemoglobin-recognition signal revealed a relatively thick and large reticular structure in the deeper layers that became denser and finer toward the upper layers. The numerical analysis revealed that the number of dermal blood vessels was 1.29-fold higher (p<0.05) in the deeper region of the lesion than that of normal skin. The CD34 immunohistochemical analysis in tender indurated erythema revealed an increased number of dermal vessels compared with normal skin in 88.9% (8/9) of the cases, suggesting that vascular network remodeling had occurred in cPN.

CONCLUSION

The photoacoustic system has an advantage in noninvasively detecting dermal blood vessel structures that are difficult to recognize by two-dimensional histopathology specimen examination and is worth evaluating in various skin diseases.

Multispectral Optoacoustic Tomography Enables In Vivo Anatomical and Functional Assessment of Human Tendons

Tendon injuries resulting from accidents and aging are increasing globally. However, key tendon functional parameters such as microvascularity and oxygen perfusion remain inaccessible via the currently available clinical diagnostic tools, resulting in disagreements on optimal treatment options. Here, a new noninvasive method for anatomical and functional characterization of human tendons based on multispectral optoacoustic tomography (MSOT) is reported. Healthy subjects are investigated using a hand-held scanner delivering real-time volumetric images. Tendons in the wrist, ankle, and lower leg are imaged in the near-infrared optical spectrum to utilize endogenous contrast from Type I collagen. Morphology of the flexor carpi ulnaris, carpi radialis, palmaris longus, and Achilles tendons are reconstructed in full. The functional roles of the flexor digitorium longus, hallicus longus, and the tibialis posterior tendons have been visualized by dynamic tracking during toe extension-flexion motion. Furthermore, major vessels and microvasculature near the Achilles tendon are localized, and the global increase in oxygen saturation in response to targeted exercise is confirmed by perfusion studies. MSOT is shown to be a versatile tool capable of anatomical and functional tendon assessments. Future studies including abnormal subjects can validate the method as a viable noninvasive clinical tool for tendinopathy management and healing monitoring.

Functional maturation and longitudinal imaging of intraportal neonatal porcine islet grafts in genetically diabetic pigs

Allogeneic intraportal islet transplantation (ITx) has become an established treatment for patients with poorly controlled type 1 diabetes. However, the loss of viable beta-cell mass after transplantation remains a major challenge. Therefore, noninvasive imaging methods for long-term monitoring of the transplant fate are required. In this study, [68Ga]Ga-DOTA-exendin-4 positron emission tomography/computed tomography (PET/CT) was used for repeated monitoring of allogeneic neonatal porcine islets (NPI) after intraportal transplantation into immunosuppressed genetically diabetic pigs. NPI transplantation (3320-15,000 islet equivalents per kg body weight) led to a reduced need for exogenous insulin therapy and finally normalization of blood glucose levels in 3 out of 4 animals after 5 to 10 weeks. Longitudinal PET/CT measurements revealed a significant increase in standard uptake values in graft-bearing livers. Histologic analysis confirmed the presence of well-engrafted, mature islet clusters in the transplanted livers. Our study presents a novel large animal model for allogeneic intraportal ITx. A relatively small dose of NPIs was sufficient to normalize blood glucose levels in a clinically relevant diabetic pig model. [68Ga]Ga-DOTA-exendin-4 PET/CT proved to be efficacious for longitudinal monitoring of islet transplants. Thus, it could play a crucial role in optimizing ITx as a curative therapy for type 1 diabetes.

3-Dimensional CT Planning for TAVR With a Novel Self-Expandable Valve in a Calcified Anatomy

Recently, a novel transfemoral self-expandable valve (JenaValve Trilogy) was granted a CE mark as a dedicated device for transfemoral treatment of both aortic valve stenosis and regurgitation. Here, we highlight the importance of 3-dimensional preprocedural planning for the optimal choice of a prosthesis in challenging anatomies by reporting an unusual case of a heavily calcified aortic sinus.

Imaging Agents for PET of Inflammatory Bowel Disease: A Review

Inflammatory bowel disease (IBD), which encompasses ulcerative colitis and Crohn disease, is a chronic inflammatory disorder resulting from an aberrant immune response, though its exact cause is unknown. The current mainstay standard of care for the diagnosis and surveillance of IBD is endoscopy. However, this methodology is invasive and images only superficial tissue structures, revealing very little about the molecular drivers of inflammation. Accordingly, there is an unmet need for noninvasive imaging tools that provide reliable and quantitative visualization of intestinal inflammation with high spatial and molecular specificity. In recent years, several PET agents for imaging IBD have been reported. Such agents allow noninvasive visualization and quantification of dynamic molecular inflammatory processes in vivo. This review focuses on recent advancements in the development of PET tracers for imaging biomarkers of interest in IBD pathogenesis, such as cell-surface molecules that are overexpressed on immune cells and cytokines that perpetuate inflammatory signaling.

Constrictive Pericarditis: An Update on Noninvasive Multimodal Diagnosis

Constrictive pericarditis (CP) is a rare condition that can affect the pericardium after every pericardial disease process and has been described even after SARS-CoV-2 infection or vaccine. In CP, the affected pericardium, usually the inner layer, is noncompliant, constraining the heart to a fixed maximum volume and impairing the diastolic function. This leads to several clinical features, that, however, can be pleomorphic. In its difficult diagnostic workup, noninvasive multimodal imaging plays a central role, providing important morphological and functional data, like the enhanced ventricular interdependence and the dissociation between intrathoracic and intracardiac pressures. An early and proper diagnosis is crucial to set an appropriate therapy, changing the prognosis of patients affected by CP. In this review, we cover in detail the main elements of each imaging technique, after a reminder of pathophysiology useful for understanding the diagnostic findings.

Noninvasive In Vivo Imaging of T-Cells during Cancer Immunotherapy Using Rare-Earth Nanoparticles

Only a minority of patients respond positively to cancer immunotherapy, and addressing this variability is an active area of immunotherapy research. Infiltration of tumors by immune cells is one of the most significant prognostic indicators of response and disease-free survival. However, the ability to noninvasively sample the tumor microenvironment for immune cells remains limited. Imaging in the near-infrared-II region using rare-earth nanocrystals is emerging as a powerful imaging tool for high-resolution deep-tissue imaging. In this paper, we demonstrate that these nanoparticles can be used for noninvasive in vivo imaging of tumor-infiltrating T-cells in a highly aggressive melanoma tumor model. We present nanoparticle synthesis and surface modification strategies for the generation of small, ultrabright, and biocompatible rare-earth nanocrystals necessary for deep tissue imaging of rare cell types. The ability to noninvasively monitor the immune contexture of a tumor during immunotherapy could lead to early identification of nonresponding patients in real time, leading to earlier interventions and better outcomes.

Metastatic renal cell carcinoma presenting as multiple cutaneous lesions visualized through reflectance confocal microscopy

We present the first case of metastatic renal cell carcinoma visualized via reflectance confocal microscopy (RCM). This case describes the RCM features of such a tumor, in an effort to improve noninvasive characterization of cutaneous metastases.

COMPARATIVE ANALYSIS OF OCT AND OCT ANGIOGRAPHY CHARACTERISTICS IN EARLY DIABETIC RETINOPATHY

PURPOSE

To assess the quantitative characteristics of optical coherence tomography (OCT) and OCT angiography (OCTA) for the objective detection of early diabetic retinopathy (DR).

METHODS

This was a retrospective and cross-sectional study, which was carried out at a tertiary academic practice with a subspecialty. Twenty control participants, 15 people with diabetics without retinopathy (NoDR), and 22 people with mild nonproliferative diabetic retinopathy (NPDR) were included in this study. Quantitative OCT characteristics were derived from the photoreceptor hyperreflective bands, i.e., inner segment ellipsoid (ISe) and retinal pigment epithelium (RPE). OCTA characteristics, including vessel diameter index (VDI), vessel perimeter index (VPI), and vessel skeleton density (VSD), were evaluated.

RESULTS

Quantitative OCT analysis indicated that the ISe intensity was significantly trending downward with DR advancement. Comparative OCTA revealed VDI, VPI, and VSD as the most sensitive characteristics of DR. Correlation analysis of OCT and OCTA characteristics revealed weak variable correlation between the two imaging modalities.

CONCLUSION

Quantitative OCT and OCTA analyses revealed photoreceptor and vascular distortions in early DR. Comparative analysis revealed that the OCT intensity ratio, ISe/RPE, has the best sensitivity for early DR detection. Weak variable correlation of the OCT and OCTA characteristics suggests that OCT and OCTA are providing supplementary information for DR detection and classification.

Noninvasive imaging exploration of phacomatosis pigmentokeratotica using high-frequency ultrasound and optical coherence tomography: Can biopsy of PPK patients be avoided?

BACKGROUND

Phacomatosis pigmentokeratotica (PPK) is a distinct and rare type of epidermal nevus syndrome characterized by coexisting nonepidermolytic organoid sebaceous nevus (SN) with one or more speckled lentiginous nevi (SLN). Atypical nevi including compound Spitz and compound dysplastic may manifest within regions of SLN. Patients with PPK, or similar atypical nevus syndromes, may be subject to a significant lifetime number of biopsies, leading to pain, scarring, anxiety, financial burden, and decreased quality of life. The current literature includes case reports, genetics, and associated extracutaneous symptoms of PPK, but use of noninvasive imaging techniques have not been explored. We aim to investigate the value of high-frequency ultrasound (HFUS) and optical coherence tomography (OCT) in discriminating morphological features of pigmented lesions and nevus sebaceous within one patient with PPK.

MATERIALS AND METHODS

Two modalities, (1) HFUS imaging, based on acoustic properties and (2) OCT imaging, based on optical properties, were used to image a patient with PPK. Benign pigmented lesions, which may raise clinical suspicion for significant atypia, and nevus sebaceous, were selected on different areas of the body to be studied.

RESULTS

Five pigmented lesions and one area of nevus sebaceous were imaged and analyzed for noninvasive features. Distinct patterns of hypoechoic features were seen on HFUS and OCT.

CONCLUSION

HFUS provides a deep view of the tissue, with ability to differentiate gross structures beneath the skin. OCT provides a smaller penetration depth and a higher resolution. We have described noninvasive features of atypical nevi and nevus sebaceous on HFUS and OCT, which indicate benign etiology.

Rapid Cellular-Resolution Skin Imaging with Optical Coherence Tomography Using All-Glass Multifocal Metasurfaces

Cellular-resolution optical coherence tomography (OCT) is a powerful tool offering noninvasive histology-like imaging. However, like other optical microscopy tools, a high numerical aperture (N.A.) lens is required to generate a tight focus, generating a narrow depth of field, which necessitates dynamic focusing and limiting the imaging speed. To overcome this limitation, we developed a metasurface platform that generates multiple axial foci, which multiplies the volumetric OCT imaging speed by offering several focal planes. This platform offers accurate and flexible control over the number, positions, and intensities of axial foci generated. All-glass metasurface optical elements 8 mm in diameter are fabricated from fused-silica wafers and implemented into our scanning OCT system. With a constant lateral resolution of 1.1 μm over all depths, the multifocal OCT triples the volumetric acquisition speed for dermatological imaging, while still clearly revealing features of stratum corneum, epidermal cells, and dermal-epidermal junctions and offering morphological information as diagnostic criteria for basal cell carcinoma. The imaging speed can be further improved in a sparse sample, e.g., 7-fold with a seven-foci beam. In summary, this work demonstrates the concept of metasurface-based multifocal OCT for rapid virtual biopsy, further providing insights for developing rapid volumetric imaging systems with high resolution and compact volume.

Technical note: Noninvasive monitoring of normal tissue radiation damage using spectral quantitative ultrasound spectroscopy

BACKGROUND

While radiation therapy (RT) is a critical component of breast cancer therapy and is known to decrease overall local recurrence rates, recent studies have shown that normal tissue radiation damage may increase recurrence risk. Fibrosis is a well-known consequence of RT, but the specific sequence of molecular and mechanical changes induced by RT remains poorly understood.

PURPOSE

To improve cancer therapy outcomes, there is a need to understand the role of the irradiated tissue microenvironment in tumor recurrence. This study seeks to evaluate the use of spectral quantitative ultrasound (spectral QUS) for real time determination of the normal tissue characteristic radiation response and to correlate these results to molecular features in irradiated tissues.

METHODS

Murine mammary fat pads (MFPs) were irradiated to 20 Gy, and spectral QUS was used to analyze tissue physical properties pre-irradiation as well as at 1, 5, and 10 days post-irradiation. Tissues were processed for scanning electron microscopy imaging as well as histological and immunohistochemical staining to evaluate morphology and structure.

RESULTS

Tissue morphological and structural changes were observed non-invasively following radiation using mid-band fit (MBF), spectral slope (SS), and spectral intercept (SI) measurements obtained from spectral QUS. Statistically significant shifts in MBF and SI indicate structural tissue changes in real time, which matched histological observations. Radiation damage was indicated by increased adipose tissue density and extracellular matrix (ECM) deposition.

CONCLUSIONS

Our findings demonstrate the potential of using spectral QUS to noninvasively evaluate normal tissue changes resulting from radiation damage. This supports further pre-clinical studies to determine how the tissue microenvironment and physical properties change in response to therapy, which may be important for improving treatment strategies.

Emerging Strategies of Engineering and Tracking Dendritic Cells for Cancer Immunotherapy

Dendritic cells (DCs), a kind of specialized immune cells, play key roles in antitumor immune response and promotion of innate and adaptive immune responses. Recently, many strategies have been developed to utilize DCs in cancer therapy, such as delivering antigens and adjuvants to DCs and using scaffold to recruit and activate DCs. Here we outline how different DC subsets influence antitumor immunity, summarize the FDA-approved vaccines and cancer vaccines under clinical trials, discuss the strategies for engineering DCs and noninvasive tracking of DCs to improve antitumor immunotherapy, and reveal the potential of artificial neural networks for the design of DC based vaccines.

Multimodality Imaging in the Detection of Ischemic Heart Disease in Women

Women with coronary artery disease tend to have a worse short and long-term prognosis relative to men and the incidence of atherosclerotic cardiovascular disease is increasing. Women are less likely to present with classic anginal symptoms when compared with men and more likely to be misdiagnosed. Several non-invasive imaging modalities are available for diagnosing ischemic heart disease in women and many of these modalities can also assist with prognostication and help to guide management. Selection of the optimal imaging modality to evaluate women with possible ischemic heart disease is a scenario which clinicians often encounter. Earlier modalities such as exercise treadmill testing demonstrate significant performance variation in men and women, while newer modalities such as coronary CT angiography, myocardial perfusion imaging and cardiac magnetic resonance imaging are highly specific and sensitive for the detection of ischemia and coronary artery disease with greater parity between sexes. Individual factors, availability, diagnostic performance, and female-specific considerations such as pregnancy status may influence the decision to select one modality over another. Emerging techniques such as strain rate imaging, CT-myocardial perfusion imaging and cardiac magnetic resonance imaging present additional options for diagnosing ischemia and coronary microvascular dysfunction.

Utility of high-resolution ultrasound in measuring subcutaneous fat thickness

OBJECTIVE

Previous studies conclude that high-resolution ultrasound (HRUS) enables noninvasive and accurate measurements of subcutaneous fat thickness. The primary objective of this cross-sectional study was to better characterize subcutaneous fat thickness measurements in a diverse patient population using HRUS. Secondarily, we sought to correlate these measurements with patients' body image.

METHODS

A cross-sectional study to measure subcutaneous fat measurements at seven distinct anatomic sites, including upper and lower extremities, submental, and torso regions, in 40 men and women of different ages and races using HRUS. Independent t-tests and analysis of variance were performed to analyze findings.

RESULTS

In our patient population, on average, women had thicker subcutaneous fat than men at all anatomic sites. Asian patients had significantly reduced fat thickness at peripheral anatomic sites, such as arms when compared to patients who identified as Black and Other (p = 0.05 and p = 0.008, respectively). Lastly, women reported decreased total body satisfaction at all anatomic sites when compared to men.

CONCLUSION

The information obtained and methods developed in this study may be utilized clinically during patient selection for fat reduction procedures, including for estimating the degree of likely benefit; for managing pathologies involving subcutaneous fat thickness alteration; and to monitor the progression of lipodystrophy secondary to disease or drugs.

Circulation Time-Optimized Albumin Nanoplatform for Quantitative Visualization of Lung Metastasis via Targeting of Macrophages

The development of molecular imaging probes to identify key cellular changes within lung metastases may lead to noninvasive detection of metastatic lesions in the lung. In this study, we constructed a macrophage-targeted clickable albumin nanoplatform (CAN) decorated with mannose as the targeting ligand using a click reaction to maintain the intrinsic properties of albumin in vivo. We also modified the number of mannose molecules on the CAN and found that mannosylated serum albumin (MSA) harboring six molecules of mannose displayed favorable pharmacokinetics that allowed high-contrast imaging of the lung, rendering it suitable for in vivo visualization of lung metastases. Due to the optimized control of functionalization and surface modification, MSA enhanced blood circulation time and active/passive targeting abilities and was specifically incorporated by mannose receptor (CD206)-expressing macrophages in the metastatic lung. Moreover, extensive in vivo imaging studies using single-photon emission computed tomography (SPECT)/CT and positron emission tomography (PET) revealed that blood circulation of time-optimized MSA can be used to discern metastatic lesions, with a strong correlation between its signal and metastatic burden in the lung.

Glycol-Chitosan-Based Technetium-99m-Loaded Multifunctional Nanomicelles: Synthesis, Evaluation, and In Vivo Biodistribution

We hereby propose the use of stable, biocompatible, and uniformly sized polymeric micelles as high-radiotracer-payload carriers at region-of-interest with negligible background activity due to no or low offsite radiolysis. We modified glycol chitosan (GC) polymer with varying levels of palmitoylation (P) and quaternization (Q). Quaternary ammonium palmitoyl glycol chitosan (GCPQ) with a Q:P ratio of 9:35 (Q9P35GC) offers >99% biocompatibility at 10 mg mL−1. Q9P35GC micelles exhibit >99% 99mTechnetium (99mTc) radiolabeling via the stannous chloride reduction method without heat. The 99mTc-Q9P35GC micelles (65 ± 3 nm) exhibit >98% 6 h serum stability at 37 °C and 7 day of radiochemical stability at 25 °C. HepG2 cells show a higher uptake of FITC-Q9P35GC than Q13P15GC and Q20P15GC. The in vivo 24 h organ cumulated activity (MBq h) order follows: liver (234.4) > kidneys (60.95) > GIT (0.73) > spleen (88.84). The liver to organ ratio remains higher than 2.4, rendering a better contrast in the liver. The radiotracer uptake decreases significantly in fibrotic vs. normal liver, whereas a blocking study with excess Q9P35GC significantly decreases the radiotracer uptake in a healthy vs. fibrotic liver. FITC-Q9P35GC shows in vivo hepato-specific uptake. Radiotracer liver uptake profile follows reversible binding kinetics with data fitting to two-tissue compartmental (2T), and graphical Ichise multilinear analysis (MA2) with lower AIC and higher R2 values, respectively. The study concludes that 99mTc-Q9P35GC can be a robust radiotracer for noninvasive hepatocyte function assessment and diagnosis of liver fibrosis. Furthermore, its multifunctional properties enable it to be a promising platform for nanotheranostic applications.

From Seeing to Simulating: A Survey of Imaging Techniques and Spatially-Resolved Data for Developing Multiscale Computational Models of Liver Regeneration

Liver regeneration, which leads to the re-establishment of organ mass, follows a specifically organized set of biological processes acting on various time and length scales. Computational models of liver regeneration largely focused on incorporating molecular and signaling detail have been developed by multiple research groups in the recent years. These modeling efforts have supported a synthesis of disparate experimental results at the molecular scale. Incorporation of tissue and organ scale data using noninvasive imaging methods can extend these computational models towards a comprehensive accounting of multiscale dynamics of liver regeneration. For instance, microscopy-based imaging methods provide detailed histological information at the tissue and cellular scales. Noninvasive imaging methods such as ultrasound, computed tomography and magnetic resonance imaging provide morphological and physiological features including volumetric measures over time. In this review, we discuss multiple imaging modalities capable of informing computational models of liver regeneration at the organ-, tissue- and cellular level. Additionally, we discuss available software and algorithms, which aid in the analysis and integration of imaging data into computational models. Such models can be generated or tuned for an individual patient with liver disease. Progress towards integrated multiscale models of liver regeneration can aid in prognostic tool development for treating liver disease.

Preoperative Imaging with [18F]-Fluorocholine PET/CT in Primary Hyperparathyroidism

Primary hyperparathyroidism (pHPT) is a common endocrine disorder due to hyperfunctioning parathyroid glands. To date, the only curing therapy is surgical removal of the dysfunctional gland, making correct detection and localization crucial in order to perform a minimally invasive parathyroidectomy. ¹⁸F-Fluorocholine positron emission tomography/computed tomography (¹⁸F-FCH PET/CT) has shown promising results for the detection of pHPT, suggesting superiority over conventional imaging with ultrasounds or scintigraphy. A total of 33 patients with pHPT who had negative or equivocal findings in conventional imaging received ¹⁸F-FCH PET/CT preoperatively and were retrospectively included. A pathological hyperfunctional parathyroid gland was diagnosed in 24 cases (positive PET, 72.7%), 4 cases showed equivocal choline uptake (equivocal PET, 12.1%), and in 5 cases, no enhanced choline uptake was evident (negative PET, 15.2%). Twelve of the twenty-four detected adenoma patients underwent surgery, and in all cases, a pathological parathyroid adenoma was resected at the site detected by PET/CT. Two of the six patients without pathological choline uptake who received a parathyroidectomy revealed no evidence of parathyroid adenoma tissue in the histopathological evaluation. This retrospective study analyzes ¹⁸F-FCH PET/CT in a challenging patient cohort with pHPT and negative or equivocal conventional imaging results and supports the use of ¹⁸F-FCH for the diagnosis of hyperfunctional parathyroid tissue, especially in this patient setting, with a 100% true positive and true negative detection rate. Our study further demonstrates the importance of ¹⁸F-FCH PET/CT for successful surgical guidance.

Transforming the treatment of psoriasis to the 21st century: Detecting subclinical therapeutic response to secukinumab using optical coherence tomography as a prognostic indicator

BACKGROUND

Optical coherence tomography (OCT) is a noninvasive imaging device that scans the skin up to 2 mm in depth. OCT can capture real-time epidermal thickness (ET) measurements and detect subclinical changes in inflammatory skin diseases like eczema and psoriasis. © 2022 Wiley Periodicals LLC.

OBJECTIVE

To determine if measuring ET with OCT can detect a subclinical therapeutic response in psoriasis treated with the biological therapy, secukinumab (an IL-17A antagonist).

DESIGN

Phase IV, single-center, open-label, and single-arm study.

PARTICIPANTS

Twenty-six consecutive patients with moderate to severe plaque psoriasis.

MEASUREMENTS

Clinical, dermoscopic, and OCT images were obtained at each visit. The clinician measured disease severity with the Investigator's Global Assessment (IGA) and Psoriasis Area And Severity Index (PASI). OCT was used to scan the ET at the center of lesional skin (ET-L), along the border, and normal skin (ET-N) on the same body plane; their difference was noted as ΔET.

RESULTS

Initially, ET-L was greater than ET-N (p < 0.0001), their differences decreased throughout the study, and there were no significant differences at Week 16 (p = 0.48). Twenty-four (92%) patients achieved a 50% reduction in PASI score (PASI50); they had lower ΔET at Weeks 0, 1, 3, 4, and 8 compared to those who did not clear (p < 0.04). Having a lower ΔET at Week 4 was associated with a shorter time to reach PASI50 (p = 0.02).

CONCLUSION

ET measurements using OCT can detect an early subclinical response to secukinumab compared to clinical scoring and identify nonresponders as early as 4 weeks.

Association of Contrast-Enhanced Ultrasound-Derived Kidney Cortical Microvascular Perfusion with Kidney Function

BACKGROUND

Individuals with chronic kidney disease (CKD) have decreased kidney cortical microvascular perfusion, which may lead to worsening kidney function over time, but methods to quantify kidney cortical microvascular perfusion are not feasible to incorporate into clinical practice. Contrast-enhanced ultrasound (CEUS) may quantify kidney cortical microvascular perfusion, which requires further investigation in individuals across the spectrum of kidney function.

METHODS

We performed CEUS on a native kidney of 83 individuals across the spectrum of kidney function and calculated quantitative CEUS-derived kidney cortical microvascular perfusion biomarkers. Participants had a continuous infusion of the microbubble contrast agent (Definity) with a flash-replenishment sequence during their CEUS scan. Lower values of the microbubble velocity (β) and perfusion index (β×A) may represent lower kidney cortical microvascular perfusion. Multivariable linear regression models tested the associations of the microbubble velocity (β) and perfusion index (β×A) with estimated glomerular filtration rate (eGFR).

RESULTS

Thirty-eight individuals with CKD (mean age±SD 65.2±12.6 years, median [IQR] eGFR 31.5 [18.9-41.5] ml/min per 1.73 m²), 37 individuals with end stage kidney disease (ESKD; age 54.8±12.3 years), and eight healthy volunteers (age 44.1±15.0 years, eGFR 117 [106-120] ml/min per 1.73 m²) underwent CEUS without side effects. Individuals with ESKD had the lowest microbubble velocity (β) and perfusion index (β×A) compared with individuals with CKD and healthy volunteers. The microbubble velocity (β) and perfusion index (β×A) had moderate positive correlations with eGFR (β: r_s=0.44, P<0.001; β×A: r_s=0.50, P<0.001). After multivariable adjustment, microbubble velocity (β) and perfusion index (β×A) remained significantly associated with eGFR (change in natural log transformed eGFR per 1 unit increase in natural log transformed biomarker: β, 0.38 [95%, CI 0.17 to 0.59]; β×A, 0.79 [95% CI, 0.45 to 1.13]).

CONCLUSIONS

CEUS-derived kidney cortical microvascular perfusion biomarkers are associated with eGFR. Future studies are needed to determine if CEUS-derived kidney cortical microvascular perfusion biomarkers have prognostic value.

Expanded LUXendin Color Palette for GLP1R Detection and Visualization In Vitro and In Vivo

The glucagon-like peptide-1 receptor (GLP1R) is expressed in peripheral tissues and the brain, where it exerts pleiotropic actions on metabolic and inflammatory processes. Detection and visualization of GLP1R remains challenging, partly due to a lack of validated reagents. Previously, we generated LUXendins, antagonistic red and far-red fluorescent probes for specific labeling of GLP1R in live and fixed cells/tissues. We now extend this concept to the green and near-infrared color ranges by synthesizing and testing LUXendin492, LUXendin551, LUXendin615, and LUXendin762. All four probes brightly and specifically label GLP1R in cells and pancreatic islets. Further, LUXendin551 acts as a chemical beta cell reporter in preclinical rodent models, while LUXendin762 allows noninvasive imaging, highlighting differentially accessible GLP1R populations. We thus expand the color palette of LUXendins to seven different spectra, opening up a range of experiments using wide-field microscopy available in most labs through super-resolution imaging and whole animal imaging. With this, we expect that LUXendins will continue to generate novel and specific insights into GLP1R biology.

Applications of hyperspectral imaging in plant phenotyping

Our ability to interrogate and manipulate the genome far exceeds our capacity to measure the effects of genetic changes on plant traits. Much effort has been made recently by the plant science research community to address this imbalance. The responses of plants to environmental conditions can now be defined using a variety of imaging approaches. Hyperspectral imaging (HSI) has emerged as a promising approach to measure traits using a wide range of wavebands simultaneously in 3D to capture information in lab, glasshouse, or field settings. HSI has been applied to define abiotic, biotic, and quality traits for optimisation of crop management.

In Vivo Reflectance Confocal Microscopy of Cutaneous Acute Graft-Versus-Host Disease: Concordance with Histopathology and Interobserver Reproducibility of a Glossary with Representative Images

BACKGROUND

The reliability to noninvasively identify features of inflammatory dermatoses by reflectance confocal microscopy (RCM) remains unknown. Lack of formal training among RCM readers can result in inconsistent assessments, limiting clinical utility. Specific consensus terminology with representative images is necessary to ensure consistent feature-level interpretation among RCM readers.

OBJECTIVES

(1) Develop a glossary with representative images of RCM features of cutaneous acute graft-versus-host disease (aGVHD) for consistent interpretation among observers, (2) assess the interobserver reproducibility among RCM readers using the glossary, and (3) determine the concordance between RCM and histopathology for aGVHD features.

METHODS

Through an iterative process of refinement and discussion among five international RCM experts, we developed a glossary with representative images of RCM features of aGVHD. From April to November 2018, patients suspected of aGVHD were imaged with RCM and subsequently biopsied. 17 lesions from 12 patients had clinically and pathologically confirmed cutaneous aGVHD. For each of these lesions, four dermatopathologists and four RCM readers independently evaluated the presence of aGVHD features in scanned histopathology slides and 1.5x1.5 mm RCM submosaics at 4 depths (blockstacks), respectively. RCM cases were adjudicated by a fifth RCM expert. Interobserver reproducibility was calculated by U statistic. Concordance between modalities was determined by fraction agreement.

RESULTS

We present a glossary with representative images of 18 aGVHD features by RCM. The average interobserver reproducibility among RCM readers (75%, confidence interval, CI: 71%-79%) did not differ significantly from dermatopathologists (80%, 76%-85%). The concordance between RCM and histopathology was 59%.

CONCLUSIONS

By using the glossary, the interobserver reproducibility among RCM readers was similar to the interobserver reproducibility among dermatopathologists. There was good concordance between RCM and histopathology to visualize aGVHD features. The implementation of RCM can now be advanced in a variety of inflammatory conditions with a validated glossary and representative image set.

Noninvasive Imaging for Patients with COVID-19 and Acute Chest Pain

Acute chest pain is a common presentation in patients with COVID-19. Although noninvasive cardiac imaging modalities continue to be important cornerstones of management, the pandemic has brought forth difficult and unprecedented challenges in the provision of timely care while ensuring the safety of patients and providers. Clinical practice has adapted to these challenges, with several recommendations and societal guidelines emerging on the appropriate use of imaging modalities. In this review, we summarize the current evidence base on the use of noninvasive cardiac imaging modalities in COVID-19 patients with acute chest pain, with a focus on acute coronary syndromes.

Ex vivo Validation of Noninvasive Epicardial and Endocardial Repolarization Mapping

Background: The detection and localization of electrophysiological substrates currently involve invasive cardiac mapping. Electrocardiographic imaging (ECGI) using the equivalent dipole layer (EDL) method allows the noninvasive estimation of endocardial and epicardial activation and repolarization times (AT and RT), but the RT validation is limited to in silico studies. We aimed to assess the temporal and spatial accuracy of the EDL method in reconstructing the RTs from the surface ECG under physiological circumstances and situations with artificially induced increased repolarization heterogeneity.

Methods: In four Langendorff-perfused pig hearts, we simultaneously recorded unipolar electrograms from plunge needles and pseudo-ECGs from a volume-conducting container equipped with 61 electrodes. The RTs were computed from the ECGs during atrial and ventricular pacing and compared with those measured from the local unipolar electrograms. Regional RT prolongation (cooling) or shortening (pinacidil) was achieved by selective perfusion of the left anterior descending artery (LAD) region.

Results: The differences between the computed and measured RTs were 19.0 ± 17.8 and 18.6 ± 13.7 ms for atrial and ventricular paced beats, respectively. The region of artificially delayed or shortened repolarization was correctly identified, with minimum/maximum RT roughly in the center of the region in three hearts. In one heart, the reconstructed region was shifted by ~2.5 cm. The total absolute difference between the measured and calculated RTs for all analyzed patterns in selectively perfused hearts (n = 5) was 39.6 ± 27.1 ms.

Conclusion: The noninvasive ECG repolarization imaging using the EDL method of atrial and ventricular paced beats allows adequate quantitative reconstruction of regions of altered repolarization.

Role of noninvasive imaging in the evaluation of intrahepatic cholangiocarcinoma: from diagnosis and prognosis to treatment response

INTRODUCTION

Intrahepatic cholangiocarcinoma is the second most common liver cancer. Desmoplastic stroma may be revealed as distinctive histopathologic findings favoring intrahepatic cholangiocarcinoma. Meanwhile, a range of imaging manifestations is often accompanied with rich desmoplastic stroma in intrahepatic cholangiocarcinoma, which can indicate large bile duct ICC, and a higher level of cancer-associated fibroblasts with poor prognosis and weak treatment response.

AREAS COVERED

We provide a comprehensive review of current state-of-the-art and recent advances in the imaging evaluation for diagnosis, staging, prognosis and treatment response of intrahepatic cholangiocarcinoma. In addition, we discuss precursor lesions, cells of origin, molecular mutation, which would cause the different histological classification. Moreover, histological classification and tumor microenvironment, which are related to the proportion of desmoplastic stroma with many imaging manifestations, would be also discussed.

EXPERT OPINION

The diagnosis, prognosis, treatment response of intrahepatic cholangiocarcinoma may be revealed as the presence and the proportion of desmoplastic stroma with a range of imaging manifestations. With the utility of radiomics and artificial intelligence, imaging is helpful for ICC evaluation. Multicentre, large-scale, prospective studies with external validation are in need to develop comprehensive prediction models based on clinical data, imaging findings, genetic parameters, molecular, metabolic, and immune biomarkers.

Characterization of Tissue Scaffolds Using Synchrotron Radiation Microcomputed Tomography Imaging

Distinguishing from other traditional imaging, synchrotron radiation microcomputed tomography (SR-μCT) imaging allows for the visualization of three-dimensional objects of interest in a nondestructive and/or in situ way with better spatial resolution, deep penetration, relatively fast speed, and/or high contrast. SR-μCT has been illustrated promising for visualizing and characterizing tissue scaffolds for repairing or replacing damaged tissue or organs in tissue engineering (TE), which is of particular advance for longitudinal monitoring and tracking the success of scaffolds once implanted in animal models and/or human patients. This article presents a comprehensive review on recent studies of characterization of scaffolds based on SR-μCT and takes scaffold architectural properties, mechanical properties, degradation, swelling and wettability, and biological properties as five separate sections to introduce SR-μCT wide applications. We also discuss and highlight the unique opportunities of SR-μCT in various TE applications; conclude this article with the suggested future research directions, including the prospective applications of SR-μCT, along with its challenges and methods for improvement in the field of TE.

Efficient Organic Upconversion Devices for Low Energy Consumption and High-Quality Noninvasive Imaging

Infrared upconversion devices (UCDs) enable low-cost visualization of infrared optical signals without utilizing a readout circuit, which is of great significance for biological recognition and noninvasive dynamic monitoring. However, UCDs suffer from inferior photon to photon (p-p) efficiency and high turn-on voltage (V_on ) for upconversion operation, hindering a further expansion in highly resolved infrared imaging. Herein, an efficient organic UCD integrating an interfacial exciplex emitter and a well-designed near-infrared (NIR) detector reveals a high efficiency up to 12.92% and a low V_on down to 1.56 V. The low V_on gives the capacity for detecting weak NIR light down to 3.2 µW cm^-2 , significantly expanding the detection power scale of UCDs. Thus, the imaging linear dynamic range (I-LDR) is highly bias-tunable, ranging from 13.23 to 84.4 dB. The high I-LDR enables highly resolved and strong-penetration bioimaging especially for thick biological sections, indicating great potential in noninvasive defect and pathological detection.

In vivo examination of healthy human skin after short-time treatment with moisturizers using confocal Raman spectroscopy and optical coherence tomography: Preliminary observations

Skin is our barrier against environmental damage. Moisturizers are widely used to increase hydration and barrier integrity of the skin; however, there are contrasting observations on their in vivo effects in real-life settings. In cosmetic studies, corneometers and tewameters are traditionally used to assess skin hydration. In this study, two novel noninvasive diagnostic techniques, optical coherence tomography (OCT) and confocal Raman spectroscopy, were used to analyze stratum corneum and epidermal thickness (ET), water content, blood flow in function of depth, skin roughness, attenuation coefficient, natural moisturizing factor, ceramides and free fatty acids, cholesterol, urea, and lactates in 20 female subjects aged between 30 and 45 before and after 2 weeks application of a commercially available moisturizing lotion on one forearm. The untreated forearm served as control. A third measurement was conducted 1 week after cessation of moisturizing to verify whether the changes in the analyzed parameters persisted. We noticed a reduction in skin roughness, an increase in ceramides and free fatty acids and a not statistically significant increase in ET. As a conclusion, short time moisturizing appears insufficient to provide significant changes in skin morphology and composition, as assessed by OCT and RS. Novel noninvasive imaging methods are suitable for the evaluation of skin response to topical moisturizers. Further studies on larger sample size and longer treatment schedules are needed to analyze changes under treatment with moisturizers and to standardize the use of novel noninvasive diagnostic techniques.

Multimodal Tracking of Hematopoietic Stem Cells from Young and Old Mice Labeled with Magnetic-Fluorescent Nanoparticles and Their Grafting by Bioluminescence in a Bone Marrow Transplant Model

This study proposes an innovative way to evaluate the homing and tracking of hematopoietic stem cells from young and old mice labeled with SPION_NIRF-Rh conjugated with two types of fluorophores (NIRF and Rhodamine), and their grafting by bioluminescence (BLI) in a bone marrow transplant (BMT) model. In an in vitro study, we isolated bone marrow mononuclear cells (BM-MNC) from young and old mice, and analyzed the physical-chemical characteristics of SPION_NIRF-Rh, their internalization, cell viability, and the iron quantification by NIRF, ICP-MS, and MRI. The in vivo study was performed in a BMT model to evaluate the homing, tracking, and grafting of young and old BM-MNC labeled with SPION_NIRF-Rh by NIRF and BLI, as well as the hematological reconstitution for 120 days. 5FU influenced the number of cells isolated mainly in young cells. SPION_NIRF-Rh had adequate characteristics for efficient internalization into BM-MNC. The iron load quantification by NIRF, ICP-MS, and MRI was in the order of 10⁴ SPION_NIRF-Rh/BM-MNC. In the in vivo study, the acute NIRF evaluation showed higher signal intensity in the spinal cord and abdominal region, and the BLI evaluation allowed follow-up (11-120 days), achieving a peak of intensity at 30 days, which remained stable around 10⁸ photons/s until the end. The hematologic evaluation showed similar behavior until 30 days and the histological results confirm that iron is present in almost all tissue evaluated. Our results on BM-MNC homing and tracking in the BMT model did not show a difference in migration or grafting of cells from young or old mice, with the hemogram analysis trending to differentiation towards the myeloid lineage in mice that received cells from old animals. The cell homing by NIRF and long term cell follow-up by BLI highlighted the relevance of the multimodal nanoparticles and combined techniques for evaluation.

In vivo NIR-II structured-illumination light-sheet microscopy

Noninvasive optical imaging with deep tissue penetration depth and high spatiotemporal resolution is important to longitudinally studying the biology at the single-cell level in live mammals, but has been challenging due to light scattering. Here, we developed near-infrared II (NIR-II) (1,000 to 1,700 nm) structured-illumination light-sheet microscopy (NIR-II SIM) with ultralong excitation and emission wavelengths up to ∼1,540 and ∼1,700 nm, respectively, suppressing light scattering to afford large volumetric three-dimensional (3D) imaging of tissues with deep-axial penetration depths. Integrating structured illumination into NIR-II light-sheet microscopy further diminished background and improved spatial resolution by approximately twofold. In vivo oblique NIR-II SIM was performed noninvasively for 3D volumetric multiplexed molecular imaging of the CT26 tumor microenvironment in mice, longitudinally mapping out CD4, CD8, and OX40 at the single-cell level in response to immunotherapy by cytosine-phosphate-guanine (CpG), a Toll-like receptor 9 (TLR-9) agonist combined with OX40 antibody treatment. NIR-II SIM affords an additional tool for noninvasive volumetric molecular imaging of immune cells in live mammals.

Noninvasive Three-Dimensional In Situ and In Vivo Characterization of Bioprinted Hydrogel Scaffolds Using the X-ray Propagation-Based Imaging Technique

Hydrogel-based three-dimensional (3D) bioprinting has been illustrated as promising to fabricate tissue scaffolds for regenerative medicine. Notably, bioprinting of hydrated and soft 3D hydrogel scaffolds with desired structural properties has not been fully achieved so far. Moreover, due to the limitations of current imaging techniques, assessment of bioprinted hydrogel scaffolds is still challenging, yet still essential for scaffold design, fabrication, and longitudinal studies. This paper presents our study on the bioprinting of hydrogel scaffolds and on the development of a novel noninvasive imaging method, based on synchrotron propagation-based imaging with computed tomography (SR-PBI-CT), to study the structural properties of hydrogel scaffolds and their responses to environmental stimuli both in situ and in vivo. Hydrogel scaffolds designed with varying structural patterns were successfully bioprinted through rigorous printing process regulations and then imaged by SR-PBI-CT within physiological environments. Subjective to controllable compressive loadings, the structural responses of scaffolds were visualized and characterized in terms of the structural deformation caused by the compressive loadings. Hydrogel scaffolds were later implanted in rats as nerve conduits for SR-PBI-CT imaging, and the obtained images illustrated their high phase contrast and were further processed for the 3D structure reconstruction and quantitative characterization. Our results show that the scaffold design and printing conditions play important roles in the printed scaffold structure and mechanical properties. More importantly, our obtained images from SR-PBI-CT allow us to visualize the details of hydrogel 3D structures with high imaging resolution. It demonstrates unique capability of this imaging technique for noninvasive, in situ characterization of 3D hydrogel structures pre- and post-implantation in diverse physiological milieus. The established imaging platform can therefore be utilized as a robust, high-precision tool for the design and longitudinal studies of hydrogel scaffold in tissue engineering.

Updates in Magnetic Resonance Venous Imaging

For years, magnetic resonance angiography (MRA) has been a leading imaging modality in the assessment of venous disease involving the pelvis and lower extremities. Current advancement in noncontrast MRA techniques enables imaging of a larger subset of patients previously excluded due to allergy or renal insufficiency, allowing for preintervention assessment and planning. In this article, the current status of MR venography, with a focus on current advancements, will be presented. Protocols and parameters for MR venographic imaging of the pelvis and lower extremities, including contrast and noncontrast enhanced techniques, will be reviewed based on a recent literature review of applied MR venographic techniques. Finally, several disease-specific entities, including pelvic congestion and compression syndromes, will be discussed with a focus on imaging parameters that may best characterize these disease processes and optimize anatomical planning prior to intervention.

Feasibility study of 68Ga-labeled CAR T cells for in vivo tracking using micro-positron emission tomography imaging

Clinical tracking of chimeric antigen receptor (CAR) T cells in vivo by positron emission tomography (PET) imaging is an area of intense interest. But the long-lived positron emitter-labeled CAR T cells stay in the liver and spleen for days or even weeks. Thus, the excessive absorbed effective dose becomes a major biosafety issue leading it difficult for clinical translation. In this study we used ⁶⁸Ga, a commercially available short-lived positron emitter, to label CAR T cells for noninvasive cell tracking in vivo. CAR T cells could be tracked in vivo by ⁶⁸Ga-PET imaging for at least 6 h. We showed a significant correlation between the distribution of ⁸⁹Zr and ⁶⁸Ga-labeled CAR T cells in the same tissues (lungs, liver, and spleen). The distribution and homing behavior of CAR T cells at the early period is highly correlated with the long-term fate of CAR T cells in vivo. And the effective absorbed dose of ⁶⁸Ga-labeled CAR T cells is only one twenty-fourth of ⁸⁹Zr-labeled CAR T cells, which was safe for clinical translation. We conclude the feasibility of ⁶⁸Ga instead of ⁸⁹Zr directly labeling CAR T cells for noninvasive tracking of the cells in vivo at an early stage based on PET imaging. This method provides a potential solution to the emerging need for safe and practical PET tracer for cell tracking clinically.

Reflectance Confocal Microscopy, Optical Coherence Tomography, and Multiphoton Microscopy in Inflammatory Skin Disease Diagnosis

BACKGROUND AND OBJECTIVES

Technological advances in medicine have brought about many novel skin imaging devices. This review aims to evaluate the scientific evidence supporting the use of noninvasive optical imaging techniques to aid in the diagnosis and prognosis of inflammatory skin diseases.

STUDY DESIGN/MATERIALS AND METHODS

PubMed and Scopus were searched in September 2020 according to PRISMA guidelines for articles using reflectance confocal microscopy (RCM), optical coherence tomography (OCT), and multiphoton microscopy (MPM) in inflammatory skin diseases, excluding studies monitoring treatment efficacy.

RESULTS

At the time of the study, there were 66 articles that addressed the utilization of noninvasive imaging in interface, spongiotic, psoriasiform, vesiculobullous, and fibrosing/sclerosing inflammatory skin dermatoses: RCM was utilized in 46, OCT in 16, and MPM in 5 articles. RCM was most investigated in psoriasiform dermatoses, whereas OCT and MPM were both most investigated in spongiotic dermatoses, including atopic dermatitis and allergic contact dermatitis.

CONCLUSIONS

There is preliminary evidence to support the diagnostic potential of noninvasive optical imaging techniques in inflammatory skin diseases. Improvements in the devices and further correlation with histology will help broaden their utility. Additional studies are needed to determine the parameters for diagnostic features, disease differentiation, and staging of inflammatory skin conditions. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Nanobodies targeting immune checkpoint molecules for tumor immunotherapy and immunoimaging (Review)

The immune checkpoint blockade is an effective strategy to enhance the anti-tumor T cell effector activity, thus becoming one of the most promising immunotherapeutic strategies in the history of cancer treatment. Several immune checkpoint inhibitor have been approved by the FDA, such as anti-CTLA-4, anti-PD-1, anti-PD-L1 monoclonal antibodies. Most tumor patients benefitted from these antibodies, but some of the patients did not respond to them. To increase the effectiveness of immunotherapy, including immune checkpoint blockade therapies, miniaturization of antibodies has been introduced. A single-domain antibody, also known as nanobody, is an attractive reagent for immunotherapy and immunoimaging thanks to its unique structural characteristic consisting of a variable region of a single heavy chain antibody. This structure confers to the nanobody a light molecular weight, making it smaller than conventional antibodies, although remaining able to bind to a specific antigen. Therefore, this review summarizes the production of nanobodies targeting immune checkpoint molecules and the application of nanobodies targeting immune checkpoint molecules in immunotherapy and immunoimaging.

Review: The Next Steps in Crop Improvement: Adoption of Emerging Strategies to Identify Bottlenecks in Sugar Flux

Sugar allocation in plants is the fundamental process that transports sugar from source to sink tissues and has a dramatic impact on crop yields. Controlling sugar allocation is required to increase crop yields, as well as biomass for biofuel production. Successful examples have demonstrated that genetic engineering of sugar partitioning offers a promising strategy to achieve this goal. However, improvement has thus far been limited by gaps in understanding of the underlying mechanisms controlling the allocation of sugars. The dynamics of sugar partitioning are minimally predictable under different conditions, between species, or in response to abiotic stresses. Here, we discuss four methodologies that have not been sufficiently exploited for the identification of bottlenecks in sugar flux. Furthermore, we suggest how these strategies can be used and combined to provide the insight needed to maximize crop yields or biomass, especially under conditions of environmental stress.

Toward Molecular Imaging of Intestinal Pathology

Inflammatory bowel disease (IBD) is defined by a chronic relapsing and remitting inflammation of the gastrointestinal tract, with intestinal fibrosis being a major complication. The etiology of IBD remains unknown, but it is thought to arise from a dysregulated and excessive immune response to gut luminal microbes triggered by genetic and environmental factors. To date, IBD has no cure, and treatments are currently directed at relieving symptoms and treating inflammation. The current diagnostic of IBD relies on endoscopy, which is invasive and does not provide information on the presence of extraluminal complications and molecular aspect of the disease. Cross-sectional imaging modalities such as computed tomography enterography (CTE), magnetic resonance enterography (MRE), positron emission tomography (PET), single photon emission computed tomography (SPECT), and hybrid modalities have demonstrated high accuracy for the diagnosis of IBD and can provide both functional and morphological information when combined with the use of molecular imaging probes. This review presents the state-of-the-art imaging techniques and molecular imaging approaches in the field of IBD and points out future directions that could help improve our understanding of IBD pathological processes, along with the development of efficient treatments.

Morphometric Optical Imaging of Microporated Nail Tissue: An Investigation of Intermethod Agreement, Reliability, and Technical Limitations

BACKGROUND AND OBJECTIVES

While optical imaging is a useful technique to quantitate morphological differences and treatment effects, comparative investigations of the various techniques are lacking. This study aimed at evaluating intermethod agreement, reliability, and technical limitations of wide-field microscopy (WFM), reflectance confocal microscopy (RCM), and optical coherence tomography (OCT) for morphometry by assessing fractionally ablated nail tissue.

STUDY DESIGN/MATERIALS AND METHODS

Fifty healthy nail clippings were processed with a fractionated CO₂ -laser (20 mJ/microbeam, density 15%), measured with calipers, and imaged using WFM, OCT, and RCM. Images were assessed for nail plate thickness, micropore dimensions, degree of poration, and artifacts. Repeated measurements (2-5) were taken to evaluate method repeatability using Cronbach's α and coefficients of variation (CoV), and estimate the intermethod correlation through linear correlation assessment (Pearson correlation coefficient [PCC]), ranked correlation (Kendall's tau; tau-c), and intraclass correlation (Shrout-Fleiss reliability coefficient; ICC).

RESULTS

The repeatability varied substantially between methods and target measurements. The level of intermethod agreement for thickness measurements performed with calipers, WFM, and OCT was high (tau-c ≥ 0.7; ICC ≥ 0.8; PCC ≥ 0.9). RCM could only image 28 out of 50 samples due to its limited penetration depth. OCT demonstrated the highest repeatability of all imaging techniques (CoV 4-7%) and nail thickness showed the highest measurement reliability (α = 0.92). Micropore dimensions correlated strongest between OCT and RCM (tau-c/ICC/PCC ≥ 0.5). All modalities were prone to artifacts, which may have adversely affected measurement variation and intermethod agreement.

CONCLUSION

Intermethod agreement and reliability appear to be highly dependent on the specific modality and target measurement. To reap the benefits of each technique while mitigating their limitations, an integrated approach to optical imaging is recommended. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Nanomedicine Approaches for Advanced Diagnosis and Treatment of Atherosclerosis and Related Ischemic Diseases

Cardiovascular diseases (CVDs) remain one of the major causes of mortality worldwide. In response to this and other worldwide health epidemics, nanomedicine has emerged as a rapidly evolving discipline that involves the development of innovative nanomaterials and nanotechnologies and their applications in therapy and diagnosis. Nanomedicine presents unique advantages over conventional medicines due to the superior properties intrinsic to nanoscopic therapies. Once used mainly for cancer therapies, recently, tremendous progress has been made in nanomedicine that has led to an overall improvement in the treatment and diagnosis of CVDs. This review elucidates the pathophysiology and potential targets of atherosclerosis and associated ischemic diseases. It may be fruitful to pursue future work in the nanomedicine-mediated treatment of CVDs based on these targets. A comprehensive overview is then provided featuring the latest preclinical and clinical outcomes in cardiovascular imaging, biomarker detection, tissue engineering, and nanoscale delivery, with specific emphasis on nanoparticles, nanostructured scaffolds, and nanosensors. Finally, the challenges and opportunities regarding the future development and clinical translation of nanomedicine in related fields are discussed. Overall, this review aims to provide a deep and thorough understanding of the design, application, and future development of nanomedicine for atherosclerosis and related ischemic diseases.

The Added Value of Longitudinal Imaging for Preclinical In Vivo Efficacy Testing of Therapeutic Compounds against Cerebral Cryptococcosis

Brain infections with Cryptococcus neoformans are associated with significant morbidity and mortality. Cryptococcosis typically presents as meningoencephalitis or fungal mass lesions called cryptococcomas. Despite frequent in vitro discoveries of promising novel antifungals, the clinical need for drugs that can more efficiently treat these brain infections remains. A crucial step in drug development is the evaluation of in vivo drug efficacy in animal models. This mainly relies on survival studies or postmortem analyses in large groups of animals, but these techniques only provide information on specific organs of interest at predefined time points. In this proof-of-concept study, we validated the use of noninvasive preclinical imaging to obtain longitudinal information on the therapeutic efficacy of amphotericin B or fluconazole monotherapy in meningoencephalitis and cryptococcoma mouse models. Bioluminescence imaging enabled the rapid in vitro and in vivo evaluation of drug efficacy, while complementary high-resolution anatomical information obtained by magnetic resonance imaging of the brain allowed a precise assessment of the extent of infection and lesion growth rates. We demonstrated a good correlation between both imaging readouts and the fungal burden in various organs. Moreover, we identified potential pitfalls associated with the interpretation of therapeutic efficacy based solely on postmortem studies, demonstrating the added value of this noninvasive dual imaging approach compared to standard mortality curves or fungal load endpoints. This novel preclinical imaging platform provides insights in the dynamic aspects of the therapeutic response and facilitates a more efficient and accurate translation of promising antifungal compounds from bench to bedside.

Image-guided mathematical modeling for pharmacological evaluation of nanomaterials and monoclonal antibodies

While plasma concentration kinetics has traditionally been the predictor of drug pharmacological effects, it can occasionally fail to represent kinetics at the site of action, particularly for solid tumors. This is especially true in the case of delivery of therapeutic macromolecules (drug-loaded nanomaterials or monoclonal antibodies), which can experience challenges to effective delivery due to particle size-dependent diffusion barriers at the target site. As a result, disparity between therapeutic plasma kinetics and kinetics at the site of action may exist, highlighting the importance of target site concentration kinetics in determining the pharmacodynamic effects of macromolecular therapeutic agents. Assessment of concentration kinetics at the target site has been facilitated by non-invasive in vivo imaging modalities. This allows for visualization and quantification of the whole-body disposition behavior of therapeutics that is essential for a comprehensive understanding of their pharmacokinetics and pharmacodynamics. Quantitative non-invasive imaging can also help guide the development and parameterization of mathematical models for descriptive and predictive purposes. Here, we present a review of the application of state-of-the-art imaging modalities for quantitative pharmacological evaluation of therapeutic nanoparticles and monoclonal antibodies, with a focus on their integration with mathematical models, and identify challenges and opportunities. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Rational Design of an Activatable Reporter for Quantitative Imaging of RNA Aberrant Splicing In Vivo

Pre-mRNA splicing, the process of removing introns from pre-mRNA and the arrangement of exons to produce mature transcripts, is a crucial step in the expression of most eukaryote genes. However, the splicing kinetics remain poorly characterized in living cells, mainly because current methods cannot provide the dynamic information of splicing events. Here, we developed a genetically encoded bioluminescence reporter for real-time imaging of the pre-mRNA splicing process in living subjects. We showed that the bioluminescence reporter is able to visualize the pre-mRNA aberrant splicing process in living cells in a dose- and time-dependent manner. Moreover, this reporter could provide quantitative and longitudinal information of splicing activity in response to exogenous splicing inhibitors in living animals. Our data suggest that this activatable reporter could serve as a promising tool for the high-throughput screening of splicing modulators, which would facilitate the drug development for human diseases caused by the abnormal splicing of mRNA.

Noninvasive Tracking of Hematopoietic Stem Cells in a Bone Marrow Transplant Model

The hematopoietic stem cell engraftment depends on adequate cell numbers, their homing, and the subsequent short and long-term engraftment of these cells in the niche. We performed a systematic review of the methods employed to track hematopoietic reconstitution using molecular imaging. We searched articles indexed, published prior to January 2020, in PubMed, Cochrane, and Scopus with the following keyword sequences: (Hematopoietic Stem Cell OR Hematopoietic Progenitor Cell) AND (Tracking OR Homing) AND (Transplantation). Of 2191 articles identified, only 21 articles were included in this review, after screening and eligibility assessment. The cell source was in the majority of bone marrow from mice (43%), followed by the umbilical cord from humans (33%). The labeling agent had the follow distribution between the selected studies: 14% nanoparticle, 29% radioisotope, 19% fluorophore, 19% luciferase, and 19% animal transgenic. The type of graft used in the studies was 57% allogeneic, 38% xenogeneic, and 5% autologous, being the HSC receptor: 57% mice, 9% rat, 19% fish, 5% for dog, porcine and salamander. The imaging technique used in the HSC tracking had the following distribution between studies: Positron emission tomography/single-photon emission computed tomography 29%, bioluminescence 33%, fluorescence 19%, magnetic resonance imaging 14%, and near-infrared fluorescence imaging 5%. The efficiency of the graft was evaluated in 61% of the selected studies, and before one month of implantation, the cell renewal was very low (less than 20%), but after three months, the efficiency was more than 50%, mainly in the allogeneic graft. In conclusion, our review showed an increase in using noninvasive imaging techniques in HSC tracking using the bone marrow transplant model. However, successful transplantation depends on the formation of engraftment, and the functionality of cells after the graft, aspects that are poorly explored and that have high relevance for clinical analysis.

Noninvasive Assessment of Coronary Artery Disease - Anatomical versus Functional Imaging and the Marginal Role of Exercise Electrocardiograms

Coronary artery disease (CAD) is the leading cause of morbidity and mortality in the industrialized countries. Assessment of symptomatic patients with suspected obstructive CAD is a common reason for a clinical visit. Noninvasive anatomical and functional imaging are established tools to rule-in and rule-out CAD, to assess the severity of disease and to determine the potential risk of future cardiovascular events. In this review, we discuss the updated Guidelines from the European Society of Cardiology on Chronic Coronary Syndromes and explore the different imaging modalities used in current clinical practice for the noninvasive assessment of CAD. The pros and cons of each method, especially comparing anatomical and functional testing, are presented. Furthermore we we address the practical clinical aspects in the selection of the optimal noninvasive tests according to clinical need.

99mTc-A1 as a Novel Imaging Agent Targeting Mesothelin-Expressing Pancreatic Ductal Adenocarcinoma

Mesothelin is a membrane-associated protein overexpressed in pancreatic ductal adenocarcinoma (PDAC). Some mesothelin-targeted therapies are in clinical development but the identification of patients eligible for such therapies is still challenging. The objective of this study was to perform the imaging of mesothelin in mice models of PDAC with a technetium-labeled anti-mesothelin single-domain antibody (^99mTc-A1). Methods: The Cancer Genomic Atlas (TCGA) database was used to determine the prognostic role of mesothelin in PDAC. ^99mTc-A1 was evaluated both in vitro in PDAC cells (SW1990 and AsPC-1) and in vivo in an experimental model of mesothelin-expressing PDAC (AsPC-1) in mice. Results: TCGA analysis showed that PDAC patients with high mesothelin expression had a shorter overall survival (P = 0.00066). The binding of ^99mTc-A1 was 2.1-fold greater in high-mesothelin-expressing AsPC-1 cells when compared to moderate-mesothelin-expressing SW1990 cells (p < 0.05). In vivo, the ^99mTc-A1 uptake was 3.5-fold higher in AsPC-1-derived tumors as compared to a technetium-labeled irrelevant antibody (^99mTc-Ctl) (p < 0.01). Conclusions: ^99mTc-A1 accurately allows imaging of mesothelin-expressing experimental PDAC tumors. Our experiments paved the way for the development of a companion test for mesothelin-targeted therapies.