Assessment of tumor hypoxia in spontaneous canine tumors after treatment with OMX, a novel H-NOX oxygen carrier, with [18F]FMISO PET/CT

BACKGROUND

Hypoxia is a detrimental factor in solid tumors, leading to aggressiveness and therapy resistance. OMX, a tunable oxygen carrier from the heme nitric oxide/oxygen-binding (H-NOX) protein family, has the potential to reduce tumor hypoxia. [18F]Fluoromisonidazole ([18F]FMISO) positron emission tomography (PET) is the most widely used and investigated method for non-invasive imaging of tumor hypoxia. In this study, we used [18F]FMISO PET/CT (computed tomography) to assess the effect of OMX on tumor hypoxia in spontaneous canine tumors.

RESULTS

Thirteen canine patients with various tumors (n = 14) were randomly divided into blocks of two, with the treatment groups alternating between receiving intratumoral (IT) OMX injection (OMX IT group) and intravenous (IV) OMX injection (OMX IV group). Tumors were regarded as hypoxic if maximum tumor-to-muscle ratio (TMRmax) was greater than 1.4. In addition, hypoxic volume (HV) was defined as the region with tumor-to-muscle ratio greater than 1.4 on [18F]FMISO PET images. Hypoxia was detected in 6/7 tumors in the OMX IT group and 5/7 tumors in the OMX IV injection group. Although there was no significant difference in baseline hypoxia between the OMX IT and IV groups, the two groups showed different responses to OMX. In the OMX IV group, hypoxic tumors (n = 5) exhibited significant reductions in tumor hypoxia, as indicated by decreased TMRmax and HV in [18F]FMISO PET imaging after treatment. In contrast, hypoxic tumors in the OMX IT group (n = 6) displayed a significant increase in [18F]FMISO uptake and variable changes in TMRmax and HV.

CONCLUSIONS

[18F]FMISO PET/CT imaging presents a promising non-invasive procedure for monitoring tumor hypoxia and assessing the efficacy of hypoxia-modulating therapies in canine patients. OMX has shown promising outcomes in reducing tumor hypoxia, especially when administered intravenously, as evident from reductions in both TMRmax and HV in [18F]FMISO PET imaging.

Long-term prognostic implications of CT angiography-derived fractional flow reserve: Results from the DISCOVER-FLOW study

BACKGROUND & OBJECTIVES

The long-term prognostic implications of CT angiography-derived fractional flow reserve (FFRCT) remains unclear. We aimed to explore the long-term outcomes of FFRCT in the first-in-human study of it.

MATERIALS & METHODS

A total of 156 vessels from 102 patients with stable coronary artery disease, who underwent coronary CT angiography (CCTA) and invasive FFR measurement, were followed. The primary endpoint was target vessel failure (TVF), including cardiovascular death, target vessel myocardial infarction, and target vessel revascularization. Outcome analysis with FFRCT was performed on a per-vessel basis using a marginal Cox proportional hazard model.

RESULTS

During median 9.9 years of follow-up, TVF occurred in 20 (12.8%) vessels. FFRCT ​≤0.80 discriminated TVF (hazard ratio [HR] 2.61, 95% confidence interval [CI] 1.06, 6.45). Among 94 vessels with deferral of percutaneous coronary intervention (PCI), TVF risk was inversely correlated with FFRCT ​(HR 0.62 per 0.1 increase, 95% CI 0.44, 0.86), with the cumulative incidence of TVF being 2.6%, 15.2%, and 28.6% for vessels with FFRCT ​>0.90, 0.81-0.90, and ≤0.80, respectively (p-for-trend 0.005). Predictive value for clinical outcomes of FFRCT was similar to that of invasive FFR (c-index 0.79 vs 0.71, P ​= ​0.28). The estimated TVF risk was higher in the deferral of PCI group than the PCI group for vessels with FFRCT ≤0.81.

CONCLUSION

FFRCT showed improved long-term risk stratification and displayed a risk continuum similar to invasive FFR.

CLINICAL TRIAL REGISTRATION

NCT01189331.

Enabling Non-invasive Tracking of Vascular Endothelial Cells Derived from Induced Pluripotent Stem Cells Using Nuclear Imaging

PURPOSE

The absence of clinically applicable imaging techniques for continuous monitoring of transplanted cells poses a significant obstacle to the clinical translation of stem cell-based therapies for vascular regeneration. This study aims to optimize a clinically applicable, non-invasive imaging technique to longitudinally monitor vascular endothelial cells (ECs) for vascular regeneration in peripheral artery disease (PAD).

METHODS

Human induced pluripotent stem cells (HiPSCs) were employed to generate ECs (HiPSC-ECs). Lentiviral vectors encoding human sodium iodide symporter (hNIS) and enhanced green fluorescent protein (eGFP) genes were introduced to HiPSCs and HiPSC-ECs at varying multiplicities of infection (MOI). Through a combination of fluorescence microscopy and flow cytometry, an optimized transduction technique for introducing hNIS-eGFP into HiPSC-ECs was established. Subsequently, single-photon emission computed tomography (SPECT) was utilized for imaging of the transduced cells in vitro and in vivo after transplantation into the gastrocnemius muscle of nude mice.

RESULTS

Lentiviral transduction resulted in sustained co-expression of hNIS and eGFP in HiPSC-ECs when transduced post-endothelial differentiation. An optimal MOI of five yielded over 90% hNIS-eGFP expression efficiency without compromising cell viability. hNIS-eGFP+ HiPSC-ECs exhibited 99mTc uptake and were detectable through SPECT in vitro. Additionally, intramuscular injection of hNIS-eGFP+ HiPSC-ECs with MatrigelTM into the hindlimbs of nude mice enabled real-time SPECT/CT tracking, from which a reduction in signal exceeding 80% was observed within 7 days.

CONCLUSIONS

This study establishes an optimized cell modification and imaging protocol for tracking transplanted cells. Future efforts will focus on enhancing cell survival and integration via improved delivery systems, thereby advancing the potential of cell-based therapies for PAD.

Characterization of the collagen network of human cheek skin using ultrasonic microscopy

Dermal collagen is the most abundant component of human skin and has a network structure that regulates the mechanical properties of the skin. Therefore, non-invasive characterization of the collagen network would be beneficial for the evaluation of skin conditions. The microscopic substructures of the network, which are individual bundles and fibers, have been optically investigated. However, the macroscopic structure of the collagen network has not been assessed. To evaluate the dermal collagen network, we developed two new indicators, volume filling factor (VFF) and collagen fiber texture (CFT), to analyze three-dimensional echo intensity maps of high-frequency ultrasonic microscopy. By identifying the difference in the elastic modulus components of the dermal layer of facial skin, the density and texture of the collagen network were characterized using VFF and CFT, respectively. These new indicators revealed that the density decreased and the texture became fine with facial age. This study demonstrates that ultrasonic microscopy is useful for investigating skin conditions, paving the way for diagnostic applications in dermatology and aesthetic medicine.

Glymphatic-lymphatic coupling: assessment of the evidence from magnetic resonance imaging of humans

The discoveries that cerebrospinal fluid participates in metabolic perivascular exchange with the brain and further drains solutes to meningeal lymphatic vessels have sparked a tremendous interest in translating these seminal findings from animals to humans. A potential two-way coupling between the brain extra-vascular compartment and the peripheral immune system has implications that exceed those concerning neurodegenerative diseases, but also imply that the central nervous system has pushed its immunological borders toward the periphery, where cross-talk mediated by cerebrospinal fluid may play a role in a range of neoplastic and immunological diseases. Due to its non-invasive approach, magnetic resonance imaging has typically been the preferred methodology in attempts to image the glymphatic system and meningeal lymphatics in humans. Even if flourishing, the research field is still in its cradle, and interpretations of imaging findings that topographically associate with reports from animals have yet seemed to downplay the presence of previously described anatomical constituents, particularly in the dura. In this brief review, we illuminate these challenges and assess the evidence for a glymphatic-lymphatic coupling. Finally, we provide a new perspective on how human brain and meningeal clearance function may possibly be measured in future.

Can segmental bioelectrical impedance be used as a measure of muscle quality?

Recent works have shown bioelectrical impedance spectroscopy (BIS) may assess tissue quality. The purpose of this project was to examine associations between ultrasound echo intensity (EI) of quadriceps muscles (vastus lateralis [VL], vastus medialis [VM], vastus intermedius [VI], rectus femoris [RF]) and BIS parameters (R0, R1, C, α, fp), and if the associations are specific to individual muscles or associated with a representation of the entire quadriceps. Twenty-two participants (age: 22 ± 4 years; BMI: 25.47 ± 3.26 kg/m2) participated in all study activities. Participants had transverse ultrasound scans of each individual quadriceps muscle taken at 25, 50, and 75 % of the muscle length to generate an average EI for the VL, VM, VI, and RF, which were further averaged to generate an EI for the entire quadriceps. For BIS, participants were seated with electrodes placed on the thigh to measure the segmental quadriceps. The Cole-impedance model parameters that best fit the BIS data for each participant was used for all analyses. Pearson's correlation coefficient (r) were calculated to determine associations between muscles' EI and BIS parameters. The results suggest averaged EI of individual VL, VM, VI, RF muscles and the average EI of the segmental quadriceps were significantly related to the R0, C, α metrics of the Cole-impedance model representing quadriceps segmental tissues. This supports that segmental BIS may be an appropriate technique for rapid evaluation of segmental muscle quality.

Standardized angiographic projections allow evaluation of coronary artery side branches with quantitative flow ratio (QFR)

Quantitative flow ratio (QFR) is a novel, software-based noninvasive method for the quantitative evaluation of coronary physiology. QFR results correlate with invasive FFR measurements in the three main epicardial coronary arteries. However, QFR data for the evaluation of coronary side branches (SB) are scarce. The evaluation of QFR-performance of SB was retrospective and prospective. Eighty-seven patients with suspected chronic coronary syndrome, who received angiography using routine core lab projections, were retrospectively analyzed. On the second part 37 patients, who received angiography using recommended standardized coronary angiography projections, were prospectively analyzed. Quantitative analysis was performed for SB with a maximum lumen diameter proximal of ≥2 mm based on quantitative coronary angiography (QCA) by two certified experts with the software QAngio XA 3D 3.2. Using routine projections, QFR computation in 55 % of the SB were obtained (123 out of 224). Using standardized projections, 85 % of SB were computed by QFR (64 out of 75; p < 0.001 vs routine projections). The fluoroscopy time for recommended projections was not significantly different as opposed to routine projections (3.75 ± 2.2 vs. 4.58 ± 3.00 min, p = 2.6986). Using the standardized projections was associated with a higher amount of contrast medium (53.44 ± 24.23 vs. 87.95 ± 43.73 ml, p < 0.01), longer overall procedure time (23.23 ± 16.35 vs. 36.14 ± 17.21 min, p < 0.01) and a higher dose area product (1152.28 ± 576.70 vs. 2540.68 ± 1774.07 cGycm2, p < 0.01). Our study shows that the blood flow of the vast majority of coronary SB can be determined non-invasively by QFR in addition to the main epicardial coronary arteries when standardized projections are used.

Exploring the dynamic behavior of leukocytes with zebrafish

Cell migration is a complex and intricate network of physical, chemical, and molecular events that ultimately leads to cell motility. This phenomenon is involved in both physiological and pathological processes such as proper immune and inflammatory responses. Dysregulation of cell migration machinery in immune cells can have a tremendous impact on the trajectory of inflammation, infection, and resolution. The small vertebrate, the zebrafish, has a remarkable capacity for genetic and pharmacological manipulation aligned to transparency that enables modulation and visualization of cell migration in vivo noninvasively. Such characteristics revolutionized the field of leukocyte biology, particularly neutrophils. In this review, we will focus on leukocyte migration and highlight findings made in the zebrafish that demonstrate how this small vertebrate system is a unique model to perform in vivo imaging and study mechanisms that regulate the dynamic behavior of immune cells in their native environment under homeostasis or upon challenge.

Kidney fibrosis: Emerging diagnostic and therapeutic strategies

An increasing number of patients worldwide suffers from chronic kidney disease (CKD). CKD is accompanied by kidney fibrosis, which affects all compartments of the kidney, i.e., the glomeruli, tubulointerstitium, and vasculature. Fibrosis is the best predictor of progression of kidney diseases. Currently, there is no specific anti-fibrotic therapy for kidney patients and invasive renal biopsy remains the only option for specific detection and quantification of kidney fibrosis. Here we review emerging diagnostic approaches and potential therapeutic options for fibrosis. We discuss how translational research could help to establish fibrosis-specific endpoints for clinical trials, leading to improved patient stratification and potentially companion diagnostics, and facilitating and optimizing development of novel anti-fibrotic therapies for kidney patients.

Non-invasive imaging in the diagnosis of combined hepatocellular carcinoma and cholangiocarcinoma

Combined hepatocellular-cholangiocarcinoma (cHCC-CC) is a rare type of primary liver cancer. It is a complex "biphenotypic" tumor type consisting of bipotential hepatic progenitor cells that can differentiate into cholangiocytes subtype and hepatocytes subtype. The prognosis of patients with cHCC-CC is quite poor with its specific and more aggressive nature. Furthermore, there are no definite demographic or clinical features of cHCC-CC, thus a clear preoperative identification and accurate non-invasive imaging diagnostic analysis of cHCC-CC are of great value. In this review, we first summarized the epidemiological features, pathological findings, molecular biological information and serological indicators of cHCC-CC disease. Then we reviewed the important applications of non-invasive imaging modalities-particularly ultrasound (US)-in cHCC-CC, covering both diagnostic and prognostic assessment of patients with cHCC-CC. Finally, we presented the shortcomings and potential outlooks for imaging studies in cHCC-CC.

Assessing engineered tissues and biomaterials using ultrasound imaging: In vitro and in vivo applications

Quantitative assessment of the structural, functional, and mechanical properties of engineered tissues and biomaterials is fundamental to their development for regenerative medicine applications. Ultrasound (US) imaging is a non-invasive, non-destructive, and cost-effective technique capable of longitudinal and quantitative monitoring of tissue structure and function across centimeter to sub-micron length scales. Here we present the fundamentals of US to contextualize its application for the assessment of biomaterials and engineered tissues, both in vivo and in vitro. We review key studies that demonstrate the versatility and broad capabilities of US for clinical and pre-clinical biomaterials research. Finally, we highlight emerging techniques that further extend the applications of US, including for ultrafast imaging of biomaterials and engineered tissues in vivo and functional monitoring of stem cells, organoids, and organ-on-a-chip systems in vitro.

Visualizing diastolic failure: Non-invasive imaging-biomarkers in patients with heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction is an increasing challenge for modern day medicine and has been drawing more attention recently. Invasive right heart catheterization represents the mainstay for the diagnosis of diastolic dysfunction, however due to its attributable risk of an invasive procedure, other non-invasive clinical pathways are trying to approach this pathology in clinical practice. Diastolic failure is complex, and imaging is based on various parameters. In addition to transthoracic echocardiography, numerous novel imaging approaches, such as cardiac magnetic resonance imaging, computed tomography, positron emission (computed) tomography or single photon emission tomography techniques are being used to supplement deeper insights into causal pathology and might open targets for dedicated therapy options. This article provides insights into these sophisticated imaging techniques, their incremental value for the diagnosis of this poorly understood disease and recent promising results for an enhanced prognostication of outcome and therapy monitoring.

The utility of cardiac magnetic resonance imaging in the diagnosis of adult patients with acute myocarditis: A systematic review and meta-analysis

BACKGROUND

The presence of myocardial late gadolinium enhancement (LGE) indicates myocyte necrosis, and assists with the diagnosis of acute myocarditis (AM). Cardiac magnetic resonance (CMR) measures other than LGE i.e. tissue characterization and myocardial structural and functional parameters, play an important diagnostic role in assessment for inflammation, as seen in AM. The aim of this systematic review was to appraise the evidence for the use of quantitative CMR measures to identify myocardial inflammation in order to diagnose of AM in adult patients.

METHODS

A systematic literature search of medical databases was performed using PRISMA principles to identify relevant CMR studies on AM in adults (2005-2020; English; PROSPERO registration CRD42020180605). Data for a range of quantitative CMR measures were extracted. Continuous variables with low heterogeneity were meta-analyzed using a random-effects model for overall effect size measured as the standard mean difference (SMD).

RESULTS

Available data from 25 studies reporting continuous quantitative 1.5 T CMR measures revealed that AM is most reliably differentiated from healthy controls using T1 mapping (SMD 1.80, p < 0.01) and T2 mapping (SMD 1.63, p < 0.01), respectively. All other measures examined including T2-weighted ratio, extracellular volume, early gadolinium enhancement ratio, right ventricular ejection fraction, and LV end-diastolic volume, mass, ejection fraction, longitudinal strain, circumferential strain, and radial strain also had discriminatory ability although with smaller standard mean difference values (|SMD| 0.32-0.96, p < 0.01 for all).

CONCLUSIONS

Meta-analysis shows that myocardial tissue characterization (T1 mapping>T2 mapping) followed by measures of left ventricular structure and function demonstrate diagnostic discriminatory ability in AM.

Intestinal Ultrasound Early on in Treatment Follow-up Predicts Endoscopic Response to Anti-TNFα Treatment in Crohn's Disease

BACKGROUND

To assess treatment response, objective measures are superior to clinical improvement in Crohn's disease [CD]. Intestinal ultrasound [IUS] is an attractive, non-invasive alternative to endoscopy, demonstrating early transmural changes after treatment initiation. Therefore, we investigated IUS and contrast-enhanced ultrasound [CEUS] to predict [early] endoscopic treatment response.

METHODS

Consecutive patients with endoscopically active CD, starting anti-TNFα therapy, were included. Clinical, biochemical, IUS, and CEUS parameters at baseline [T0], after 4-8 weeks [T1] and 12-34 weeks [T2] were collected. The most severely inflamed segment at endoscopy (highest segmental Simplified Endoscopic Score for Crohn's Disease [SES-CD]) and IUS (highest segmental bowel wall thickness [BWT]) was identified. At T2, endoscopic response [decrease in SES-CD ≥ 50%] and remission [SES-CD = 0] were scored.

RESULTS

A total of 40 patients were included: 14 reached endoscopic remission and 17 endoscopic response. At T1 (3.1 mm [1.9-4.2] vs 5.3 mm [3.8-6.9], p = 0.005) and T2 (2.0 mm [1.8-3.1] vs 5.1 [3.0-6.3] mm, p = 0.002) BWT was lower in patients with endoscopic remission. At T1 and T2, 18% (area under the receiver operating curve [AUROC]: 0.77; odds ratio [OR]: 10.80, p = 0.012) and 29% [AUROC: 0.833; OR: 37.50, p = 0.006] BWT decrease predicted endoscopic response, respectively. To determine endoscopic remission, BWT 3.2 mm was most accurate [AUROC: 0.94; OR: 39.42, p < 0.0001] at T2. In addition, absence of colour Doppler signal [OR: 13.76, p = 0.03] and the CEUS parameter wash-out rate [OR: 0.76, p = 0.019] improved the prediction model.

CONCLUSIONS

Reduction in BWT, already after 4-8 weeks of follow-up, predicted endoscopic response and remission. CEUS parameters were of limited value. Furthermore, we have provided accurate cut-offs for BWT reflecting endoscopic response and remission at different time points.

Non-invasive imaging of oral potentially malignant and malignant lesions: A systematic review and meta-analysis

Non-invasive (NI) imaging techniques have been developed to overcome the limitations of invasive biopsy procedures, which is the gold standard in diagnosis of oral dysplasia and Oral Squamous Cell Carcinoma (OSCC). This systematic review and meta- analysis was carried out with an aim to investigate the efficacy of the NI-imaging techniques in the detection of dysplastic oral potentially malignant disorders (OPMDs) and OSCC. Records concerned in the detection of OPMDs, Oral Cancer were identified through search in PubMed, Science direct, Cochrane Library electronic database (January 2000 to October 2020) and additional manual searches. Out of 529 articles evaluated for eligibility, 56 satisfied the pre-determined inclusion criteria, including 13 varying NI-imaging techniques. Meta-analysis consisted 44 articles, wherein majority of the studies reported Autofluorescence (AFI-38.6%) followed by Chemiluminescence (CHEM), Narrow Band Imaging (NBI) (CHEM, NBI-15.9%), Fluorescence Spectroscopy (FS), Diffuse Reflectance Spectroscopy (DRS), (FS, DRS-13.6%) and 5aminolevulinic acid induced protoporphyrin IX fluorescence (5ALA induced PPIX- 6.8%). Higher sensitivities (Sen) and specificities (Spe) were obtained using FS (Sen:74%, Spe:96%, SAUC=0.98), DRS (Sen:79%, Spe:86%, SAUC = 0.91) and 5 ALA induced PPIX (Sen:91%, Spe:78%, SAUC = 0.98) in the detection of dysplastic OPMDs from non-dysplastic lesions(NDLs). AFI, FS, DRS, NBI showed higher sensitivities and SAUC (>90%) in differentiating OSCC from NDLs. Analysed NI-imaging techniques suggests the higher accuracy levels in the diagnosis of OSCC when compared to dysplastic OPMDs. 5 ALA induced PPIX, DRS and FS showed evidence of superior accuracy levels in differentiation of dysplastic OPMDs from NDLs, however results need to be validated in a larger number of studies.

European Society of Cardiology guidance for the diagnosis and management of cardiovascular disease during the COVID-19 pandemic: part 1-epidemiology, pathophysiology, and diagnosis

AIMS

Since its emergence in early 2020, the novel severe acute respiratory syndrome coronavirus 2 causing coronavirus disease 2019 (COVID-19) has reached pandemic levels, and there have been repeated outbreaks across the globe. The aim of this two-part series is to provide practical knowledge and guidance to aid clinicians in the diagnosis and management of cardiovascular disease (CVD) in association with COVID-19.

METHODS AND RESULTS

A narrative literature review of the available evidence has been performed, and the resulting information has been organized into two parts. The first, reported here, focuses on the epidemiology, pathophysiology, and diagnosis of cardiovascular (CV) conditions that may be manifest in patients with COVID-19. The second part, which will follow in a later edition of the journal, addresses the topics of care pathways, treatment, and follow-up of CV conditions in patients with COVID-19.

CONCLUSION

This comprehensive review is not a formal guideline but rather a document that provides a summary of current knowledge and guidance to practicing clinicians managing patients with CVD and COVID-19. The recommendations are mainly the result of observations and personal experience from healthcare providers. Therefore, the information provided here may be subject to change with increasing knowledge, evidence from prospective studies, and changes in the pandemic. Likewise, the guidance provided in the document should not interfere with recommendations provided by local and national healthcare authorities.

Quantitative magnetic resonance imaging to aid clinical decision making in autoimmune hepatitis

BACKGROUND

In autoimmune hepatitis (AIH), clinical practice and treatment guidelines frequently diverge as a reflection of disease heterogeneity and challenges in achieving standardised care. We sought to explore the utility of multiparametric (mp) MR in patients with AIH, and the impact of this technology on physicians' decision making and intended patient management.

METHODS

82 AIH patients, recruited from two sites between June and November 2019 as part of an observational cohort study, underwent non-contrast MRI alongside their standard clinical investigations. Correlations between iron-corrected T1 (cT1) and other markers of disease were investigated alongside the utility of imaging markers to risk stratify patients in biochemical remission. The impact of mpMR on clinical decision making was evaluated using pairwise t-tests. The discriminatory ability of the imaging markers was assessed using area under the receiver operating characteristic curves (AUCs).

FINDINGS

cT1 had a significant impact on clinician intended patient management (p<0.0001). cT1 correlated with ALT (p = 0.0005), AST (p<0.001), IgG (p = 0.0005), and liver stiffness (p<0.0001). Patients in deep biochemical remission (N = 11; AST/ALT <50% upper limit of normal [ULN] and IgG <12 g/L) had low cT1, while 7/34 in normal biochemical remission (AST/ALT between 50 and 100% of ULN) had high cT1 and were at risk of disease flare. cT1 measures of disease heterogeneity, ALP and bilirubin made the best predictor of those not in biochemical remission (AUC:0.85).

INTERPRETATION

This study investigates the impact of mpMR results on intended clinical management in a real world setting. Findings showed that mpMR demonstrated a significant impact on clinical management of AIH and has the potential to inform patient risk stratification.

FUNDING

This paper presents independent research supported by the Innovate UK grant (104,915).

Imaging of the Nail Unit in Psoriatic Patients - a Systematic Scoping Review of Techniques and Terminology

Background

The growing interest in the visualization of psoriatic nail unit changes has led to the discovery of an abundance of image characteristics across various modalities.

Objective

To identify techniques for non‐invasive imaging of nail unit structures in psoriatic patients and review extracted image features to unify the diverse terminology.

Methods

For this systematic scoping review, we included studies available on PubMed and Embase, independently extracted image characteristics, and semantically grouped the identified features to suggest a preferred terminology for each technique.

Results

After screening 753 studies, 67 articles on the visualization of clinical and subclinical psoriatic changes in the nail plate, matrix, bed, folds and hyponychium were included. We identified 4 optical and 3 radiological imaging techniques for the assessment of surface (dermoscopy [n = 16], capillaroscopy [n = 12]), sub‐surface (ultrasound imaging [n = 36], optical coherence tomography [n = 4], fluorescence optical imaging [n = 3]), and deep‐seated psoriatic changes (magnetic resonance imaging [n = 2], positron emission tomography‐computed tomography [n = 1]). By condensing 244 image feature descriptions into a glossary of 82 terms, overall redundancy was cut by 66.4% (37.5%–77.1%). More than 75% of these image features provide additional disease‐relevant information that is not captured using conventional clinical assessment scales.

Conclusions

This review has identified, unified, and contextualized image features and related terminology for non‐invasive imaging of the nail unit in patients with psoriatic conditions. The suggested glossary could facilitate the integrative use of non‐invasive imaging techniques for the detailed examination of psoriatic nail unit structures in research and clinical practice.

European Society of Cardiology guidance for the diagnosis and management of cardiovascular disease during the COVID-19 pandemic: part 1-epidemiology, pathophysiology, and diagnosis

AIMS

Since its emergence in early 2020, the novel severe acute respiratory syndrome coronavirus 2 causing coronavirus disease 2019 (COVID-19) has reached pandemic levels, and there have been repeated outbreaks across the globe. The aim of this two-part series is to provide practical knowledge and guidance to aid clinicians in the diagnosis and management of cardiovascular disease (CVD) in association with COVID-19.

METHODS AND RESULTS

A narrative literature review of the available evidence has been performed, and the resulting information has been organized into two parts. The first, reported here, focuses on the epidemiology, pathophysiology, and diagnosis of cardiovascular (CV) conditions that may be manifest in patients with COVID-19. The second part, which will follow in a later edition of the journal, addresses the topics of care pathways, treatment, and follow-up of CV conditions in patients with COVID-19.

CONCLUSION

This comprehensive review is not a formal guideline but rather a document that provides a summary of current knowledge and guidance to practicing clinicians managing patients with CVD and COVID-19. The recommendations are mainly the result of observations and personal experience from healthcare providers. Therefore, the information provided here may be subject to change with increasing knowledge, evidence from prospective studies, and changes in the pandemic. Likewise, the guidance provided in the document should not interfere with recommendations provided by local and national healthcare authorities.

Assessing Human Embryonic Stem Cell-Derived Dopaminergic Neuron Progenitor Transplants Using Non-invasive Imaging Techniques

PURPOSE

Human pluripotent stem cell (hPSC)-derived dopaminergic neuron progenitor cells (DAPCs) are a potential therapy for Parkinson's disease (PD). However, their intracranial administration raises safety concerns including uncontrolled proliferation, migration and inflammation. Here, we apply a bimodal imaging approach to investigate the fate of DAPC transplants in the rat striatum.

PROCEDURES

DAPCs co-expressing luciferase and ZsGreen or labelled with micron-sized particles of iron oxide (MPIOs) were transplanted in the striatum of RNU rats (n = 6 per group). DAPCs were tracked in vivo using bioluminescence and magnetic resonance (MR) imaging modalities.

RESULTS

Transgene silencing in differentiating DAPCs accompanied with signal attenuation due to animal growth rendered the bioluminescence undetectable by week 2 post intrastriatal transplantation. However, MR imaging of MPIO-labelled DAPCs showed that transplanted cells remained at the site of injection for over 120 days. Post-mortem histological analysis of DAPC transplants demonstrated that labelling with either luciferase/ZsGreen or MPIOs did not affect the ability of cells to differentiate into mature dopaminergic neurons. Importantly, labelled cells did not elicit increased glial reactivity compared to non-labelled cells.

CONCLUSIONS

In summary, our findings support the transplantation of hPSC-derived DAPCs as a safe treatment for PD.

PET Imaging of Post-infarct Myocardial Inflammation

PURPOSE OF REVIEW

To examine the use of positron emission tomography (PET) for imaging post-infarct myocardial inflammation and repair.

RECENT FINDINGS

Dysregulated immune responses after myocardial infarction are associated with adverse cardiac remodelling and an increased likelihood of ischaemic heart failure. PET imaging utilising novel tracers can be applied to visualise different components of the post-infarction inflammatory and repair processes. This approach could offer unique pathophysiological insights that could prove useful for the identification and risk-stratification of individuals who would ultimately benefit most from emerging immune-modulating therapies. PET imaging could also bridge the clinical translational gap as a surrogate measure of drug efficacy in early-stage clinical trials in patients with myocardial infarction. The use of hybrid PET/MR imaging, in particular, offers the additional advantage of simultaneous in vivo molecular imaging and detailed assessment of myocardial function, viability and tissue characterisation. Further research is needed to realise the true clinical translational value of PET imaging after myocardial infarction.

Non-invasive imaging for the diagnosis of acute rejection in transplantation: The next frontier

Acute rejection is a leading cause of organ transplant failure and the most common indication for re-transplantation. Clinically, suspicion of acute rejection is often dependent upon serum laboratory values which may only manifest after organ injury. The gold standard for diagnosis requires an invasive biopsy which can carry serious clinical risks including bleeding and graft loss as well as the possibility of sampling error. The use of noninvasive imaging modalities to monitor transplanted organs is of great clinical value, particularly as a tool for early detection of graft dysfunction or acute rejection. Herein, we provide an overview of the existing literature evaluating noninvasive imaging modalities of solid organ and cellular allografts after transplantation, including both preclinical and clinical studies.

Quantitative multiparametric magnetic resonance imaging can aid non-alcoholic steatohepatitis diagnosis in a Japanese cohort

BACKGROUND

Non-invasive assessment of non-alcoholic steatohepatitis (NASH) is increasing in desirability due to the invasive nature and costs associated with the current form of assessment; liver biopsy. Quantitative multiparametric magnetic resonance imaging (mpMRI) to measure liver fat (proton density fat fraction) and fibroinflammatory disease [iron-corrected T1 (cT1)], as well as elastography techniques [vibration-controlled transient elastography (VCTE) liver stiffness measure], magnetic resonance elastography (MRE) and 2D Shear-Wave elastography (SWE) to measure stiffness and fat (controlled attenuated parameter, CAP) are emerging alternatives which could be utilised as safe surrogates to liver biopsy.

AIM

To evaluate the agreement of non-invasive imaging modalities with liver biopsy, and their subsequent diagnostic accuracy for identifying NASH patients.

METHODS

From January 2019 to February 2020, Japanese patients suspected of NASH were recruited onto a prospective, observational study and were screened using non-invasive imaging techniques; mpMRI with LiverMultiScan^®, VCTE, MRE and 2D-SWE. Patients were subsequently biopsied, and samples were scored by three independent pathologists. The diagnostic performances of the non-invasive imaging modalities were assessed using area under receiver operating characteristic curve (AUC) with the median of the histology scores as the gold standard diagnoses. Concordance between all three independent pathologists was further explored using Krippendorff’s alpha (a) from weighted kappa statistics.

RESULTS

N = 145 patients with mean age of 60 (SD: 13 years.), 39% females, and 40% with body mass index ≥ 30 kg/m² were included in the analysis. For identifying patients with NASH, MR liver fat and cT1 were the strongest performing individual measures (AUC: 0.80 and 0.75 respectively), and the mpMRI metrics combined (cT1 and MR liver fat) were the overall best non-invasive test (AUC: 0.83). For identifying fibrosis ≥ 1, MRE performed best (AUC: 0.97), compared to VCTE-liver stiffness measure (AUC: 0.94) and 2D-SWE (AUC: 0.94). For assessment of steatosis ≥ 1, MR liver fat was the best performing non-invasive test (AUC: 0.92), compared to controlled attenuated parameter (AUC: 0.75). Assessment of the agreement between pathologists showed that concordance was best for steatosis (a = 0.58), moderate for ballooning (a = 0.40) and fibrosis (a = 0.40), and worst for lobular inflammation (a = 0.11).

CONCLUSION

Quantitative mpMRI is an effective alternative to liver biopsy for diagnosing NASH and non-alcoholic fatty liver, and thus may offer clinical utility in patient management.

Evaluation of non-invasive imaging parameters in coronary microvascular disease: a systematic review

Background

Coronary microvascular dysfunction (CMD) is an important underlying cause of angina pectoris. Currently, no diagnostic tool is available to directly visualize the coronary microvasculature. Invasive microvascular reactivity testing is the diagnostic standard for CMD, but several non-invasive imaging techniques are being evaluated. However, evidence on reported non-invasive parameters and cut-off values is limited. Thus, we aimed to provide an overview of reported non-invasive parameters and corresponding cut-off values for CMD.

Methods

Pubmed and EMBASE databases were systematically searched for studies enrolling patients with angina pectoris without obstructed coronary arteries, investigating at least one non-invasive imaging technique to quantify CMD. Methodological quality assessment of included studies was performed using QUADAS-2.

Results

Thirty-seven studies were included. Ten cardiac magnetic resonance studies reported MPRI and nine positron emission tomography (PET) and transthoracic echocardiography (TTE) studies reported CFR. Mean MPRI ranged from 1.47 ± 0.36 to 2.01 ± 0.41 in patients and from 1.50 ± 0.47 to 2.68 ± 0.49 in controls without CMD. Reported mean CFR in PET and TTE ranged from 1.39 ± 0.31 to 2.85 ± 1.35 and 1.69 ± 0.40 to 2.40 ± 0.40 for patients, and 2.68 ± 0.83 to 4.32 ± 1.78 and 2.65 ± 0.65 to 3.31 ± 1.10 for controls, respectively.

Conclusions

This systematic review summarized current evidence on reported parameters and cut-off values to diagnose CMD for various non-invasive imaging modalities. In current clinical practice, CMD is generally diagnosed with a CFR less than 2.0. However, due to heterogeneity in methodology and reporting of outcome measures, outcomes could not be compared and no definite reference values could be provided.

A new deep learning approach integrated with clinical data for the dermoscopic differentiation of early melanomas from atypical nevi

BACKGROUND

Timely recognition of malignant melanoma (MM) is challenging for dermatologists worldwide and represents the main determinant for mortality. Dermoscopic examination is influenced by dermatologists' experience and fails to achieve adequate accuracy and reproducibility in discriminating atypical nevi (AN) from early melanomas (EM).

OBJECTIVE

We aimed to develop a Deep Convolutional Neural Network (DCNN) model able to support dermatologists in the classification and management of atypical melanocytic skin lesions (aMSL).

METHODS

A training set (630 images), a validation set (135) and a testing set (214) were derived from the idScore dataset of 979 challenging aMSL cases in which the dermoscopic image is integrated with clinical data (age, sex, body site and diameter) and associated with histological data. A DCNN_aMSL architecture was designed and then trained on both dermoscopic images of aMSL and the clinical/anamnestic data, resulting in the integrated "iDCNN_aMSL" model. Responses of 111 dermatologists with different experience levels on both aMSL classification (intuitive diagnosis) and management decisions (no/long follow-up; short follow-up; excision/preventive excision) were compared with the DCNNs models.

RESULTS

In the lesion classification study, the iDCNN_aMSL achieved the best accuracy, reaching an AUC = 90.3 %, SE = 86.5 % and SP = 73.6 %, compared to DCNN_aMSL (SE = 89.2 %, SP = 65.7 %) and intuitive diagnosis of dermatologists (SE = 77.0 %; SP = 61.4 %).

CONCLUSIONS

The iDCNN_aMSL proved to be the best support tool for management decisions reducing the ratio of inappropriate excision. The proposed iDCNN_aMSL model can represent a valid support for dermatologists in discriminating AN from EM with high accuracy and for medical decision making by reducing their rates of inappropriate excisions.

Cardiac Computed Tomography Angiography Follow-Up of Resorbable Magnesium Scaffolds

INTRODUCTION

An ancillary advantage of bioresorbable scaffolds is the possibility of non-invasive imaging assessment of the treated coronary segment. Cardiac computed tomography angiography (CCTA) studies of resorbable magnesium scaffolds (RMS) are scarce.

METHODS

In this collaborative, international study, nine patients who had an RMS implanted underwent CCTA as part of follow-up assessment. Core-lab blinded quantitative and qualitative assessment was performed by an independent CCTA investigator.

RESULTS

Eight studies were amenable for quantitative analysis, and the blinded CT investigator successfully located and evaluated patency of RMS in all cases. The CCTA follow-up in-scaffold percentage diameter stenosis and area stenosis was 22.2% (12.4-30) and 39.1% (0.23-0.50), in keeping with mild in-scaffold late loss and underlying plaque growth. Moreover, a detailed coronary plaque characterization at treated segments was feasible (fibrous plaque in 69.9%, fibrofatty in 17.13%, necrotic in 4.78% and calcium in 5.72%). As in 6 out of 8 cases, the presentation was an acute coronary syndrome, these preliminary results could suggest plaque stabilization and a good coronary vessel healing with RMS.

CONCLUSION

Non-invasive, follow-up assessment of RMS with CCTA is feasible. Further CCTA studies for either clinical or research purposes with the present and upcoming generation of resorbable magnesium scaffolds are warranted.

Novel Positron Emission Tomography Tracers for Imaging Vascular Inflammation

Purpose of Review

To provide a focused update on recent advances in positron emission tomography (PET) imaging in vascular inflammatory diseases and consider future directions in the field.

Recent Findings

While PET imaging with ¹⁸F-fluorodeoxyglucose (FDG) can provide a useful marker of disease activity in several vascular inflammatory diseases, including atherosclerosis and large-vessel vasculitis, this tracer lacks inflammatory cell specificity and is not a practical solution for imaging the coronary vasculature because of avid background myocardial signal. To overcome these limitations, research is ongoing to identify novel PET tracers that can more accurately track individual components of vascular immune responses. Use of these novel PET tracers could lead to a better understanding of underlying disease mechanisms and help inform the identification and stratification of patients for newly emerging immune-modulatory therapies.

Summary

Future research is needed to realise the true clinical translational value of PET imaging in vascular inflammatory diseases.

Coronary inflammation: why searching, how to identify and treat it

Inflammation plays an important role in the development of atherosclerotic lesions. A variety of stimuli promote atherosclerosis, including increased LDL cholesterol in blood, exposure to tobacco, diabetes mellitus, hypertension, or rheological stress. Inflammatory cells have an established role in the growth of atherosclerotic lesions. Macrophages recognize and internalise ox-LDL to eventually become lipid-laden foam cells, the hallmark cellular component of atheroma. Infiltrating CD4-T cells have a role too, by interacting with ox-LDL and other antigens. Cytokines secreted by inflammatory cells stimulate smooth muscle cells migration whilst macrophages produce metalloprotease that lead to fibrous cap rupture. The necrotic debris of died macrophages and smooth muscle cells help to continue the inflammatory process. The inflammatory response can also directly activate platelets and promote thrombus formation at the surface of complicated coronary plaques. The CANTOS trial can be waived as an innovative study promoting a novel approach of personalized medicine. In patients with previous myocardial infarction, high-sensitivity C-reactive protein level of 2 mg and normal LDL level (<70 mg/dL), canakinumab a therapeutic monoclonal antibody targeting interleukin-1β, at a dose of 150 mg every 3 months, led to a significant reduction of the primary efficacy end point: nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death at 48 months. Based on the CANTOS results, patients on statins and residual inflammatory risk as assessed by means of a high-sensitivity CRP >2 mg/l at baseline have a high risk of future cardiac events, comparable to that of statin-treated patients with suboptimal cholesterol LDL level. The inhibition of interleukin-1β by means of canakinumab, which is only one of many potential anti-inflammatory pathways, open new perspectives, showing that a selective inhibition of the inflammatory pathway may be beneficial in reducing cardiovascular risk. In a process of personalized medicine, there is need to accurately identify patients at high risk of events, to be treated with potent statins or anti-inflammatory drugs. Perhaps in the near future a more specific assessment of coronary inflammations, possibly obtained with imaging modalities (either invasive or non-invasive), will better select patients at risk of events. In this scenario, in the setting of secondary prevention, OCT may serve the scope of identifying vulnerable plaques with local aggregates of inflammatory cells. Future studies are needed to understand the clinical effectiveness of strategies based on invasive coronary assessment.

Utility of Imaging Modalities in Coronary Lesions With Borderline Fractional Flow Reserve

BACKGROUND

Coronary intervention is routinely deferred in intermediate lesions with fractional flow reserve (FFR) ≥ 0.80. Patients with borderline FFR (0.80-0.85) who were initially deferred, have been shown to have higher risk of future interventions; however, the data is limited, and the long term prognosis in these patients remains unknown. We assessed the utility of adjunctive imaging modalities to determine the need for intervention in lesions with borderline FFR.

METHODS

We retrospectively evaluated consecutive patients who underwent coronary angiography at Einstein Medical Center from January 2013 to April 2016. All patients with borderline FFR (0.80-0.85) were included. Patients were divided into Defer or Perform intervention groups based on additional available or procured clinical data. The Perform group was further stratified into intervention With or Without adjunctive imaging guidance (including intravascular ultrasound, optical coherence tomography, echocardiography, and exercise or pharmacologic stress test). Follow-up data was collected for all patients, which included future target lesion revascularization (TLR) and major adverse cardiac events (MACE; all-cause and cardiovascular mortality and acute coronary syndromes).

RESULTS

A total of 196 patients were eligible. Median (IQR) FFR in Perform and Defer groups was 0.81 (0.8-0.83) and 0.84 (0.82-0.85) respectively. Median (IQR) follow up was 21 (13-29) and 25 (15-36) months respectively. Overall MACE rate in Perform group (n = 101) was 20.8% (n = 21) and Defer group (n = 95) was 15.8% (n = 15). The stratified MACE rate in Perform group With imaging guidance (n = 57) was 17.5% (n = 10) and Without imaging guidance (n = 44) was 25% (n = 11). Overall, the FFR only guided management (n = 196) led to MACE rate of 18.4% (n = 36); whereas, FFR With imaging guidance (n = 136) led to MACE rate of 16.2% (n = 22). The p values were non-significant in each of the above group comparisons due to relatively low numbers with trends as noted.

CONCLUSIONS

Our study suggests that intervention of coronary lesions with borderline FFR under imaging guidance, although not significant, trends towards improved cardiovascular outcomes compared with intervention in this group without adjunctive imaging. These findings are merely speculative without achieving statistical significance in a small subset and need to be further validated in a large scale prospective study.

Angiography-based quantitative coronary contrast-flow ratio measurements correlate with myocardial ischemia assessed by stress MRI

Contrast-flow quantitative flow ratio (cQFR) is a new technology for quantitative evaluation of coronary stenosis using computational fluid dynamics based on angiograms. The aim of this study was to assess the sensitivity and specificity of cQFR to detect myocardial ischemia using stress magnetic resonance imaging (MRI) as a reference standard. Patients who received stress MRI and coronary angiography were selected from the hospital database. Relevant ischemia on stress MRI was defined as a perfusion deficit in ≥ 2 of 16 segments. cQFR was quantitated based on 3-dimensional quantitative coronary angiography using QAngio XA3D1.1 software by two blinded and independent investigators. A cQFR of ≤ 0.80 was considered abnormal. Among 87 patients 230 vessels met the criteria for full analysis by cQFR (88%). In vascular territories with a significant perfusion deficit, cQFR was significantly lower compared to areas with normal perfusion (0.72 (0.62–0.78) vs. 0.96 (0.89–0.99); p < 0.001). The sensitivity of cQFR in detecting significant epicardial stenoses of coronary vessels with documented ischemia in stress MRI was 81% (68–90%), the specificity was 88% (82–92%). Diameter stenoses (DS) and area stenoses (AS) in vessels with positive stress MRI were significantly higher than in vessels without ischemia (DS 59.1% (49.4–68.4%) vs. 34.8% (27.1–46.1%) p < 0.001; AS 75.6% (63.0–85.2%) vs. 45.0% (30.8–63.6%), p < 0.001). The analysis reveals a high correlation between coronary stenosis measured by cQFR and ischemic areas detected by stress MRI. The data set the stage to plan randomized studies assessing cQFR measurements with regard to clinical outcomes.

DnaJ-PKAc fusion induces liver inflammation in a zebrafish model of fibrolamellar carcinoma

Fibrolamellar carcinoma (FLC) is a rare liver cancer that affects adolescents and young adults. Genomic analysis of FLC has revealed a 400 kb deletion in chromosome 19 that leads to the chimeric transcript DNAJB1-PRKACA (DnaJ-PKAc), comprised of the first exon of heat shock protein 40 (DNAJB1) and exons 2-10 of the catalytic subunit of protein kinase A (PRKACA). Here, we report a new zebrafish model of FLC induced by ectopic expression of zebrafish Dnaja-Pkaca (zfDnaJa-Pkaca) in hepatocytes that is amenable to live imaging of early innate immune inflammation. Expression of zfDnaJa-Pkaca in hepatocytes induces hepatomegaly and increased hepatocyte size. In addition, FLC larvae exhibit early innate immune inflammation characterized by early infiltration of neutrophils and macrophages into the liver microenvironment. Increased Caspase-a (the zebrafish homolog for human caspase-1) activity was also found in the liver of FLC larvae, and pharmacological inhibition of Tnfα and caspase-a decreased liver size and inflammation. Overall, these findings show that innate immune inflammation is an early feature in a zebrafish model of FLC and that pharmacological inhibition of TNFα or caspase-1 activity might be targets to treat inflammation and progression in FLC patients.This article has an associated First Person interview with the first author of the paper.

Non-invasive Imaging Techniques: From Histology to In Vivo Imaging : Chapter of Imaging in Oncology

In this chapter, we will introduce and review molecular-sensitive imaging techniques, which close the gap between ex vivo and in vivo analysis. In detail, we will introduce spontaneous Raman spectral imaging, coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS), second-harmonic generation (SHG) and third-harmonic generation (THG), two-photon excited fluorescence (TPEF), and fluorescence lifetime imaging (FLIM). After reviewing these imaging techniques, we shortly introduce chemometric methods and machine learning techniques, which are needed to use these imaging techniques in diagnostic applications.

Dual-modal non-invasive imaging in vitro and in vivo monitoring degradation of PLGA scaffold based gold nanoclusters

Biodegradable scaffolds play an important role in tissue engineering, and appropriate degradation and resorption rates of these scaffolds are necessary to accommodate tissue growth. Synthetic polymers are frequently used because of their ease of production, good biocompatibility and controllable degradation rates. However, monitoring the degradation of these polymers in vivo by a noninvasive approach remains limited. In this study, we designed a composite scaffold by labeling poly(lactic-co-glycolic acid) (PLGA) with gold nanoclusters (Au NCs), which were used for tracking in vivo degradation through dual-modal fluorescence/computed tomography (CT) imaging. The diameter of the Au NCs was approximately 2.5 nm, and the emission peak was at a wavelength of 700 nm. After labeling PLGA with the Au NCs, the fluorescence intensity of the Au NC/PLGA composite scaffold reached 9.0 × 10⁹ (p/s/cm²/sr)/(μW/cm²), and the CT density of the scaffold increased to 200 HU. After the composite scaffold was implanted subcutaneously into nude mice, a continuous decrease in the fluorescence signal and CT value was observed. The mean fluorescence intensity was 8.3 × 10⁹, 3.17 × 10⁹, 2.26 × 10⁹, 2.11 × 10⁹, and 1.82 × 10⁹ (p/s/cm²/sr)/(μW/cm²) from the first week to the fifth week, respectively. The mean CT value changed from 222.6 to 185.9, 149.1, 112.5, and 55.2 (Hounsfield unit, HU) at the different timepoints. Compared with the change in the fluorescence intensity, the change in the CT value was similar to the change in the weight, and the Pearson correlation coefficient between the change in the CT value and weight was 0.8626. Furthermore, the structure and morphology of the scaffolds at different timepoints were analyzed by three-dimensional (3-D) reconstruction. This novel method of noninvasive dynamic monitoring of biodegradable polymers in vivo provides insight into choosing suitable biomaterials for tissue engineering and regenerative medicine.

Cardiovascular magnetic resonance: Stressing the future

Non-invasive cardiac stress imaging plays a central role in the assessment of patients with known or suspected coronary artery disease. The current guidelines suggest estimation of the myocardial ischaemic burden as a criterion for revascularisation on prognostic grounds despite the lack of standardised reporting of the magnitude of ischaemia on various non-invasive imaging methods. Future studies should aim to accurately describe the relationship between myocardial ischaemic burden as assessed by cardiovascular magnetic resonance imaging and mortality.

Non-invasive Risk Stratification for Coronary Artery Disease: Is It Time for Subclassifications?

PURPOSE OF REVIEW

Coronary artery disease (CAD) is the leading contributor to cardiovascular disease; it is the most prevalent non-communicable disease globally and has high morbidity, mortality and health care cost. Risk stratification is defined as prevention or containment of disease prior to it occurring or progressing, and non-invasive surrogates include history, examination, biomarkers and non-invasive imaging. This review aims to highlight advancement in current diagnostic strategies and explores gaps for CAD secondary to atherosclerosis and non-obstructive vascular diseases.

RECENT FINDINGS

Cardiac risk scores have largely proven inadequate in risk stratifying heterogeneous patient populations. Greater emphasis should also be provided to posttest risk stratification. Non-invasive imaging with MRI is the most accurate but least cost efficacious presently due to availability and expertise. Echocardiography and nuclear imaging have good accuracy, but radiation limits the latter. Novel echocardiographic technologies may increase its appeal. Cardiac CT angiography is increasingly promising. Non-invasive and minimally invasive imaging has significantly influenced the cost-efficacy trajectory of coronary artery disease diagnosis and management. Recent studies suggest that future guidelines will incorporate more subclassifications from the findings of these novel technologies and for more diverse patient demographics.

Sensitive bioluminescence imaging of fungal dissemination to the brain in mouse models of cryptococcosis

Cryptococcus neoformans is a leading cause of fungal brain infection, but the mechanism of dissemination and dynamics of cerebral infection following pulmonary disease are poorly understood. To address these questions, non-invasive techniques that can study the dynamic processes of disease development and progression in living animal models or patients are required. As such, bioluminescence imaging (BLI) has emerged as a powerful tool to evaluate the spatial and temporal distribution of infection in living animals. We aimed to study the time profile of the dissemination of cryptococcosis from the lung to the brain in murine models by engineering the first bioluminescent C. neoformans KN99α strain, expressing a sequence-optimized red-shifted luciferase. The high pathogen specificity and sensitivity of BLI was complemented by the three-dimensional anatomical information from micro-computed tomography (μCT) of the lung and magnetic resonance imaging (MRI) of the brain. These non-invasive imaging techniques provided longitudinal readouts on the spatial and temporal distribution of infection following intravenous, intranasal or endotracheal routes of inoculation. Furthermore, the imaging results correlated strongly with the fungal load in the respective organs. By obtaining dynamic and quantitative information about the extent and timing of brain infections for individual animals, we found that dissemination to the brain after primary infection of the lung is likely a late-stage event with a timeframe that is variable between animals. This novel tool in Cryptococcus research can aid the identification of host and pathogen factors involved in this process, and supports development of novel preventive or therapeutic approaches.

Summary: A novel combination of bioluminescence and anatomical imaging non-invasively identified the timeframe and extent of Cryptococcus neoformans dissemination to the brain in animal models of systemic and pulmonary fungal infection.

Cowpea mosaic virus nanoparticles for cancer imaging and therapy

Nanoparticle platforms are particularly attractive for theranostic applications due to their capacity for multifunctionality and multivalency. Some of the most promising nano-scale scaffold systems have been co-opted from nature including plant viruses such as cowpea mosaic virus (CPMV). The use of plant viruses like CPMV as viral nanoparticles is advantageous for many reasons; they are non-infectious and nontoxic to humans and safe for use in intravital imaging and drug delivery. The CPMV capsid icosahedral shape allows for enhanced multifunctional group display and the ability to carry specific cargoes. The native tropism of CPMV for cell-surface displayed vimentin and the enhanced permeability and retention effect allow them to preferentially extravasate from tumor neovasculature and efficiently penetrate tumors. Furthermore, CPMVs can be engineered via several straightforward chemistries to display targeting and imaging moieties on external, addressable residues and they can be loaded internally with therapeutic drug cargoes. These qualities make them highly effective as biocompatible platforms for tumor targeting, intravital imaging and cancer therapy.

Magnetic 3D scaffold: A theranostic tool for tissue regeneration and non-invasive imaging in vivo

We report an osteoconducting magnetic 3D scaffold using Fe²⁺ doped nano-hydroxyapatite-Alginate-Gelatin (AGHFe1) for Magnetic Resonance Imaging based non-invasive monitoring of bone tissue regeneration. In rat cranial defect model, the scaffold facilitated non-invasive monitoring of cell migration, inflammatory response and matrix deposition by unique changes in transverse relaxation time (T2). Cell infiltration resulted in a considerable increase in T2 from ~37 to ~62 ms, which gradually returned to that of native bone (~23 ms) by 90 days. We used this method to compare in vivo performance of scaffold with bone-morphogenic protein-2 (AGHFe2) or faster degrading (AGHFe3). MRI and histological analysis over 90 days showed non-uniform bone formation in AGHFe1 with ∆T2 (T2_{Native bone} - T2 _{Regenerated bone}) ~13 ms, whereas, AGHFe2 and AGHFe3 showed ∆T2 ~ 09 and 05 ms respectively, suggesting better bone formation in AGHFe3. Thus, we show that MR-contrast enabled scaffold can help better assessment of bone-regeneration non-invasively.

Targeting mannose receptor expression on macrophages in atherosclerotic plaques of apolipoprotein E-knockout mice using 68Ga-NOTA-anti-MMR nanobody: non-invasive imaging of atherosclerotic plaques

Background

Rupture-prone atherosclerotic plaques are characterized by heavy macrophage infiltration, and the presence of certain macrophage subsets might be a sign for plaque vulnerability. The mannose receptor (MR, CD206) is over-expressed in several types of alternatively activated macrophages. In this study, our objective was to evaluate the feasibility of a Gallium-68 (⁶⁸Ga)-labelled anti-MR nanobody (⁶⁸Ga-anti-MMR Nb) for the visualization of MR-positive (MR⁺) macrophages in atherosclerotic plaques of apolipoprotein E-knockout (ApoE-KO) mice.

Results

NOTA-anti-MMR Nb was labelled with ⁶⁸Ga with radiochemical purity > 95%. In vitro cell-binding studies demonstrated selective and specific binding of the tracer to M2a macrophages. For in vivo atherosclerotic plaque imaging studies, ⁶⁸Ga-NOTA-anti-MMR Nb was injected into ApoE-KO and control mice intravenously (i.v.) and scanned 1 h post-injection for 30 min using a dedicated animal PET/CT. Focal signals could be detected in aortic tissue of ApoE-KO mice, whereas no signal was detected in the aortas of control mice. ⁶⁸Ga-NOTA-anti-MMR Nb uptake was detected in atherosclerotic plaques on autoradiographs and correlated well with Sudan-IV-positive areas. The calculated ratio of plaque-to-normal aortic tissue autoradiographic signal intensity was 7.7 ± 2.6 in aortas excised from ApoE-KO mice. Immunofluorescence analysis of aorta cross-sections confirmed predominant MR expression in macrophages located in the fibrous cap layer and shoulder region of the plaques.

Conclusions

⁶⁸Ga-NOTA-anti-MMR Nb allows non-invasive PET/CT imaging of MR expression in atherosclerotic lesions in a murine model and may represent a promising tool for clinical imaging and evaluation of plaque (in)stability.

Engineering Strategies for Oral Therapeutic Enzymes to Enhance Their Stability and Activity

Oral application of therapeutic enzymes is a promising and non-invasive administration that improves patient compliance. However, the gastrointestinal tract poses several challenges to the oral delivery of proteins, including harsh pH conditions and digestive proteases. A promising way to stabilise enzymes during their gastrointestinal route is by modification with polymers that can provide both steric shielding and selective interaction in different digestive compartments. We give an overview of modification technologies for oral enzymes ranging from functionalisation of native proteins, to site-specific mutation and protein-polymer engineering. We specifically focus on enzymes that are active directly in the gastrointestinal lumen and not systemically absorbed. In addition, we discuss examples of microparticle and nanoparticle encapsulated enzymes for improved oral delivery. The modification of orally administered enzymes offers a broad chemical variability and may be a promising tool for enhancing their gastrointestinal stability.

Assessment of reflectance confocal microscopy for non-invasive selection of optimal ovarian cortex fragments for autotransplantation

RESEARCH QUESTION

Can reflectance confocal microscopy (RCM) be used to determine follicle density in human ovarian cortex fragments that are intended for fertility restoration?

DESIGN

RCM was used on living cortex tissue fragments derived from five bovine ovaries and 13 human ovaries. All tissue fragments were cryopreserved and thawed before RCM analysis. Follicle numbers and distribution were determined by RCM and histology. Before and after RCM, general tissue viability and follicle integrity were assessed by a glucose uptake assay and neutral red staining, respectively.

RESULTS

RCM can detect all stages of follicle development in living ovarian tissue to a maximum depth of 250 µm. In bovine tissue, all follicles were located within this 0-250 µm range. In human ovarian tissue, follicles were also present below the 250 µm RCM threshold, implying that only a percentage of the total number of follicles could be detected with RCM. The percentage of follicles detected by RCM appeared to be age dependent. The RCM procedure did not affect the glucose uptake by the tissue, whereas neutral red staining indicated a high level of follicle survival.

CONCLUSION

In this proof of concept study, we have shown that RCM is a promising technique to determine the density of follicles ex vivo in living human ovarian cortex fragments, apparently without compromising the vitality of the tissue. Safety studies and further optimization of the RCM technique with a focus on increasing the penetration depth are required before clinical use of RCM.

Automatic detection of perforator vessels using infrared thermography in reconstructive surgery

PURPOSE

Knowing the location of the blood vessels supplying the skin and subcutaneous tissue is a requirement during the planning of tissue transfer in reconstructive surgery. Commonly used imaging techniques such as computed tomography angiography and indocyanine green angiography expose the patient to radiation or a contrast agent, respectively. Infrared thermal imaging was evaluated with success as a non-invasive alternative. To support the interpretation of thermograms, a method to automatically detect the perforators was developed and evaluated.

METHODS

A system consisting of a thermal camera, a PC and custom software was developed. The temperature variations of the skin surface were analysed to extract the perforator locations. A study was conducted to assess the performance of the algorithm by comparing the detection results of the algorithm with manually labelled thermal images by two clinicians of the deep inferior epigastric perforator flap of 20 healthy volunteers.

RESULTS

The F measure, precision and recall were used to evaluate the system performance. The median F measure is 0.833, the median precision is 0.80, and the median recall is 0.907.

CONCLUSION

The results of this study showed that it is possible to automatically and reliably detect the skin perforators in thermograms despite their weak temperature signature. Infrared thermal imaging is a non-invasive and contactless approach suitable for intraoperative use. Combined with a computer-assisted tool for the automatic detection of perforator vessels, it is a relevant alternative intraoperative imaging method to the standard indocyanine green angiography.

Non-invasive Characterization of Focal Arrhythmia with Electromechanical Wave Imaging in Vivo

There is currently no established method for the non-invasive characterization of arrhythmia and differentiation between endocardial and epicardial triggers at the point of care. Electromechanical wave imaging (EWI) is a novel ultrasound-based imaging technique based on time-domain transient strain estimation that can map and characterize electromechanical activation in the heart in vivo. The objectives of this initial feasibility study were to determine that EWI is capable of differentiating between endocardial and epicardial sources of focal rhythm and, as a proof-of-concept, that EWI could characterize focal arrhythmia in one patient with premature ventricular contractions (PVCs) before radiofrequency (RF) ablation treatment. First, validation of EWI for differentiation of surface of origin was performed in seven (n = 7) adult dogs using four epicardial and four endocardial pacing protocols. Second, one (n = 1) adult patient diagnosed with PVC was imaged with EWI before the scheduled RF ablation procedure, and EWI results were compared with mapping procedure results. In dogs, EWI was capable of detecting whether pacing was of endocardial or epicardial origin in six of seven cases (86% success rate). In the PVC patient, EWI correctly identified both regions and surface of origin, as confirmed by results from the electrical mapping obtained from the RF ablation procedure. These results reveal that EWI can map the electromechanical activation across the myocardium and indicate that EWI could serve as a valuable pre-treatment planning tool in the clinic.

Altered Hand Temperatures Following Transradial Cardiac Catheterization: A Thermography Study

BACKGROUND

There is concern about potential detrimental effects of transradial access (TRA) on radial artery structure, endothelial and hand function. This thermography study evaluated TRA impact on hand microvascular perfusion.

METHODS AND RESULTS

We prospectively measured hand thermography, radial and ulnar artery size and blood flow velocities in both catheterization and non-catheterization hands at baseline and 30-days after TRA in 158 patients. There were no differences in radial or ulnar arterial diameters or velocities pre- and post-TRA in catheterization and non-catheterization hands (p = NS). The absolute total hand thermography values post-TRA were increased in both catheterization and non-catheterization hand (pre-TRA 30.4 ± 2.9 vs. post-TRA 31.6 ± 2.6 p < 0.01; pre-TRA 30.2 ± 2.9, post-TRA 31.6 ± 2.6 p < 0.01, respectively). After ulnar artery occlusion, hand temperatures decreased in both catheterization and non-catheterization hands, both pre- and post-TRA and were similar in the catheterization and non-catheterization hands (p = NS). Total hand temperature decreased with ulnar artery occlusion and was significantly attenuated post-TRA (p < 0.001 both catheterization and non-catheterization hands).

CONCLUSIONS

TRA is associated with temperature changes in both catheterization and non-catheterization hands at one month after the index procedure. These changes likely represent a systemic response to local TRA stimulus.

The effect of size and polymer architecture of doxorubicin-poly(ethylene) glycol conjugate nanocarriers on breast duct retention, potency and toxicity

Although systemic administration of chemotherapeutic agents is routinely used for treating invasive breast cancer, the only therapeutic options for ductal carcinoma in situ (DCIS) are surgery and radiation. Treating DCIS by delivering drugs locally to the affected milk duct offers significant advantages over systemic administration, including reduced systemic and breast toxicities, as well as a greatly reduced need for surgery and radiation. In this study, mammary gland retention and toxicity of intraductally administered poly(ethylene) glycol-doxorubicin (PEG-DOX) polymeric conjugate nanocarriers of varying molecular sizes and architectures were investigated. Nanocarriers were formed by conjugating one or more copies of doxorubicin to PEG polymers, of varying molecular weights (5, 10, 20, and 40 kDa) and architectures (linear, four-arm and eight-arm). Cytotoxicity against MCF7 cells, a human breast cancer cell line, was assessed, and IC₅₀ values were calculated. The nanocarriers were intraductally administered into the mammary glands of female retired breeder Sprague-Dawley rats. Whole body images were captured using in vivo optical imaging, and changes in ductal structure as well local inflammation were monitored. Fluorescence intensities were monitored, over time, to evaluate nanocarrier mammary gland retention half-lives (t_1/2). The IC₅₀ values of PEG-DOX nanocarriers against MCF7 cells were 40 kDa PEG-(DOX)₄ (1.23 μM) < 5 kDa PEG-DOX (1.76 μM) < 40 kDa PEG-(DOX)₈ (3.49 μM) < 10 kDa PEG-DOX (3.86 μM) < 20 kDa PEG-DOX (8.96 μM) < 40 kDa PEG-DOX (18.11 μM), whereas the IC₅₀ of free DOX was only 0.14 μM. The t_1/2 of linear 5, 20, and 40 kDa nanocarriers were 2.2 ± 0.3, 3.6 ± 0.6, and 13.1 ± 3.4 h, whereas the retention t_1/2 of 4- and 8-arm 40 kDa nanocarriers were 14.9 ± 5.6 h and 11.9 ± 2.9 h, respectively. The retention t_1/2 of free doxorubicin was 2.0 ± 0.4 h, which was significantly shorter than that of the linear and branched 40 kDa PEG-DOX nanocarriers. Increased molecular weight and decreased branching both demonstrated a strong correlation to enhanced mammary gland retention. Intraductally administered free doxorubicin resulted in ductal damage, severe inflammation and generation of atypical cell neoplasms, whereas PEG-DOX nanocarriers induced only minor and transient inflammation (i.e., damaged epithelial cells and detached cellular debris). The 40 kDa 4-arm PEG-DOX nanocarrier demonstrated the longest ductal retention half-life, the lowest IC₅₀ (i.e., most potent), and minimal ductal damage and inflammation. The current results suggest that PEG-DOX nanocarriers with prolonged ductal retention may present the best option for intraductal treatment of DCIS, due to their low local toxicity and potential for sustained therapeutic effect.

Noninvasive epicardial and endocardial mapping of premature ventricular contractions

Aims

The aim of the present study was to estimate the accuracy of a novel non-invasive epicardial and endocardial electrophysiology system (NEEES) for mapping ectopic ventricular depolarizations.

Methods and results

The study enrolled 20 patients with monomorphic premature ventricular contractions (PVCs) or ventricular tachycardia (VT). All patients underwent pre-procedural computed tomography or magnetic resonance imaging of the heart and torso. Radiographic data were semi-automatically processed by the NEEES to reconstruct a realistic 3D model of the heart and torso. In the electrophysiology laboratory, body-surface electrodes were connected to the NEEES followed by unipolar EKG recordings during episodes of PVC/VT. The body-surface EKG data were processed by the NEEES using its inverse-problem solution software in combination with anatomical data from the heart and torso. The earliest site of activation as denoted on the NEEES 3D heart model was compared with the PVC/VT origin using a 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. A total of 21 PVC/VT morphologies were analysed and ablated. The chamber of interest was correctly diagnosed non-invasively in 20 of 21 (95%) PVC/VT cases. In 18 of the 21 (86%) cases, the correct ventricular segment was diagnosed. Catheter ablation resulted in acute success in 19 of the 20 (95%) patients, whereas 1 patient underwent successful surgical ablation. During 6 months of follow-up, 19 of the 20 (95%) patients were free from recurrence off antiarrhythmic drugs.

Conclusion

The NEEES accurately identified the site of PVC/VT origin. Knowledge of the potential site of the PVC/VT origin may aid the physician in planning a successful ablation strategy.

Taxonomy of segmental myocardial systolic dysfunction

The terms used to describe different states of myocardial health and disease are poorly defined. Imprecision and inconsistency in nomenclature can lead to difficulty in interpreting and applying trial outcomes to clinical practice. In particular, the terms ‘viable’ and ‘hibernating’ are commonly applied interchangeably and incorrectly to myocardium that exhibits chronic contractile dysfunction in patients with ischaemic heart disease. The range of inherent differences amongst imaging modalities used to define myocardial health and disease add further challenges to consistent definitions. The results of several large trials have led to renewed discussion about the classification of dysfunctional myocardial segments. This article aims to describe the diverse myocardial pathologies that may affect the myocardium in ischaemic heart disease and cardiomyopathy, and how they may be assessed with non-invasive imaging techniques in order to provide a taxonomy of myocardial dysfunction.