Coherent optical nanotweezers for ultracold atoms.

There has been a recent surge of interest and progress in creating subwavelength free-space optical potentials for ultracold atoms. A key open question is whether geometric potentials, which are repulsive and ubiquitous in the creation of subwavelength free-space potentials, forbid the creation of narrow traps with long lifetimes. Here, we show that it is possible to create such traps. We propose two schemes for realizing subwavelength traps and demonstrate their superiority over existing proposals. We analyze the lifetime of atoms in such traps and show that long-lived bound states are possible. This work allows for subwavelength control and manipulation of ultracold matter, with applications in quantum chemistry and quantum simulation.

Realization of a stroboscopic optical lattice for cold atoms with subwavelength spacing.

Optical lattices are typically created via the ac Stark shift and are limited by diffraction to periodicities ⩾ λ/2, where λ is the wavelength of light used to create them. Lattices with smaller periodicities may be useful for many-body physics with cold atoms and can be generated by stroboscopic application of a phase-shifted lattice with subwavelength features. Here we demonstrate a λ/4-spaced lattice by stroboscopically applying optical Kronig-Penney-like potentials which are generated using spatially dependent dark states. We directly probe the periodicity of the λ/4-spaced lattice by measuring the average probability density of the atoms loaded into the ground band of the lattice. We measure lifetimes of atoms in this lattice and discuss the mechanisms that limit the applicability of this stroboscopic approach.

Nanoscale Atomic Density Microscopy.

Quantum simulations with ultracold atoms typically create atomic wavefunctions with structures at optical length scales, where direct imaging suffers from the diffraction limit. In analogy to advances in optical microscopy for biological applications, we use a non-linear atomic response to surpass the diffraction limit. Exploiting quantum interference, we demonstrate imaging with super-resolution of λ/50 and excellent temporal resolution of 500 ns. We characterize our microscope's performance by measuring the ensemble averaged probability density of atoms within the unit cells of an optical lattice, and observe the dynamics of atoms excited into motion. This approach can be readily applied to image any atomic or molecular system, as long as it hosts a three-level system.

Floquet engineering of optical lattices with spatial features and periodicity below the diffraction limit.

Floquet engineering or coherent time periodic driving of quantum systems has been successfully used to synthesize Hamiltonians with novel properties. In ultracold atomic systems, this has led to experimental realizations of artificial gauge fields, topological band structures, and observation of dynamical localization, to name just a few. Here we present a Floquet-based framework to stroboscopically engineer Hamiltonians with spatial features and periodicity below the diffraction limit of light used to create them, by time-averaging over various configurations of a 1D optical Kronig-Penney (KP) lattice. The KP potential is a lattice of narrow subwavelength barriers spaced by half the optical wavelength ( λ / 2 ) and arises from the nonlinear optical response of the atomic dark state. Stroboscopic control over the strength and position of this lattice requires time-dependent adiabatic manipulation of the dark-state spin composition. We investigate adiabaticity requirements, and shape our time-dependent light fields to respect these requirements. We apply this framework to show that a λ / 4 -spaced lattice can be synthesized using realistic experimental parameters. As an example, we discuss mechanisms that limit lifetimes in these lattices, explore candidate systems with their limitations, and study adiabatic loading into the ground band of these lattices.

Dark State Optical Lattice with a Subwavelength Spatial Structure.

We report on the experimental realization of a conservative optical lattice for cold atoms with a subwavelength spatial structure. The potential is based on the nonlinear optical response of three-level atoms in laser-dressed dark states, which is not constrained by the diffraction limit of the light generating the potential. The lattice consists of a one-dimensional array of ultranarrow barriers with widths less than 10 nm, well below the wavelength of the lattice light, physically realizing a Kronig-Penney potential. We study the band structure and dissipation of this lattice and find good agreement with theoretical predictions. Even on resonance, the observed lifetimes of atoms trapped in the lattice are as long as 44 ms, nearly 10^{5} times the excited state lifetime, and could be further improved with more laser intensity. The potential is readily generalizable to higher dimensions and different geometries, allowing, for example, nearly perfect box traps, narrow tunnel junctions for atomtronics applications, and dynamically generated lattices with subwavelength spacings.

A Dynamic Three-Dimensional Air Pollution Exposure Model for Hong Kong.

INTRODUCTION: High-density high-rise cities have become a more prominent feature globally. Air quality is a significant public health risk in many of these cities. There is a need to better understand the extent to which vertical variation in air pollution and population mobility in such cities affect exposure and exposure-response relationships in epidemiological studies. METHODS: We used a novel strategy to execute a staged model development that incorporated horizontal and vertical pollutant dispersion, building infiltration, and population mobility patterns in estimating traffic-related air pollution (TRAP) exposures in the Hong Kong Special Administrative Region (HK SAR).Two street-level spatial monitoring campaigns were undertaken to facilitate the creation of a two-dimensional land-use regression (LUR) model. A network of approximately 100 passive nitric oxide-nitrogen dioxide (NO-NO2) monitors was deployed for two-week periods during the cool and warm seasons. Sampling locations were selected based on population and road network density with a range of physical and geographical characteristics represented. Eight sets of portable monitors for black carbon (BC) and particulate matter ≤2.5 µm in aerodynamic diameter (PM2.5) were rotated so as to be deployed at 80 locations for a 24-hour period. Land-use, geographical, and emissions layers were combined with the spatial monitoring campaign results to create spatiotemporal exposure models.Vertical air pollution monitoring was carried out at six strategic locations for two weeks in the warm season and two weeks in the cool season. Continuous measurements were carried out at four different heights of a residential building and on both sides of a street canyon. The heights ranged from as close to street level as practically possible up to a maximum of 50 meters (i.e., below the 20th floor). Paired indoor monitoring was included to allow the calculation of infiltration coefficients to feed into the dynamic component of the exposure model.The final phase of model development addressed population mobility. A population-representative travel behavior survey (n = 89,358) was used to produce the dynamic component of the model, with time-weighted exposure estimates split between home and work or school. Transport microenvironment exposures were taken from published literature. Time-activity exposure estimates were split by age, sex, and employment status.Development of the exposure model in distinct packages allowed the application of a staged approach to an existing cohort data set. Mortality risk estimates for an elderly cohort of 66,000 Hong Kong residents were calculated using increasing exposure model complexity. RESULTS: The street-level (2-dimensional [2D]) LUR modeling captured important spatial parameters and represented spatial patterns of air quality in Hong Kong that were consistent with the literature. Higher concentrations of gaseous pollutants were centered in Kowloon and the northern region of Hong Kong Island. PM2.5 and BC predictions exhibited a north-south/west-east gradient, with higher concentrations in the northwest due to regional transport of particulate pollutants from Mainland China. While the degree of explained variance of the models was in line with other LUR modeling efforts in Asia, R2 values ranged from 0.46 (NO2) to 0.59 (PM2.5).Exponential decay rates (k) were calculated at each monitoring location. While it was clear that k values were higher during the warm season than the cool season, no robust patterns were identified relating to the canyon physical parameters. Therefore, a single decay rate was used for each pollutant across the whole region for derivation of the 3-dimensional (3D) exposure layer (k = 0.004 and 0.012 for PM2.5 and BC, respectively). An alternative decay profile that capped decay at 20 meters above street level was proposed and evaluated. The electrochemical sensors deployed during the canyon campaigns did not exhibit the degree of interunit precision necessary to detect vertical variations in gaseous pollutants, and these results were excluded from the study.We found that values of the median infiltration efficiencies (Finf) for both BC and PM2.5 were especially high during the cool season (91%). Finf values were somewhat lower during the warm season (81% and 88% for PM2.5 and BC, respectively), and we found a significant negative correlation between air conditioning use and Finf. The Finf for a mechanically ventilated office building was 45% and 40% during the cool and warm seasons, respectively.Dynamic exposure estimates were compared against home outdoor estimates. As expected, the addition of an indoor component decreased time-weighted exposure estimates, which were balanced out to some extent by the inclusion of transport microenvironments. Overall, mean time-weighted exposures for the full dynamic model were around 20% lower than home outdoor estimates.Higher levels of exposures were found with working adults and students than for those neither in work nor study. This was due to the increased mobility of people going to work or school. The exposures to PM2.5, BC, and NO2 were, respectively, 13%, 39%, and 14% higher for people who were under age 18, compared with people who were 65 or older. Exposure estimates for the female population were approximately 4% lower.The availability of an existing cohort data set of elderly Hong Kong residents (n = 66,820) facilitated the calculation and comparison of mortality risk estimates for the different exposure models.Overall, results indicated that the application of exposure estimates that incorporated infiltration, vertical, and to a lesser extent, dynamic components resulted in higher hazard ratios (HRs) than the standard street-level model and increased the number of significant associations with all-natural-cause, cardiovascular, and respiratory mortality outcomes. CONCLUSIONS: The results from the study provided the first evidence that considering air pollution exposure in a dynamic 3D landscape would benefit epidemiological studies. Higher HRs and a greater number of significant associations were found between mortality and pollutant exposures that would not have been found had standard 2D exposure models been used. Dynamic models can also identify differential exposures between population subtypes (e.g., students and working adults; those neither in work nor study).Improved urban building design appears to be stimulating the dispersion of local TRAP in street canyons. Conversely, Finf values found in naturally ventilated buildings were high, and residences provided little protection from ambient air pollution.We have demonstrated that the creation of effective advanced exposure models is possible in Asian cities without an undue burden on resources. We recommend that vertical exposure patterns be incorporated in future epidemiological studies in high-rise cities where the floor of residence is recorded in health record data.

Diverse prognostic value of the GTn promoter polymorphism in squamous cell and adeno carcinoma of the oesophagus.

The basal transcription of heme oxygenase-1 (HO-1) regulation is dependent upon a GT repeat germ line polymorphism (GTn) in the promoter of the HO-1 gene. We determined the prognostic value of HO-1 promoter polymorphism on the natural postoperative course of complete resected oesophageal cancer. Genomic DNA from 297 patients was amplified by polymerase chain reaction and sequenced. The results were correlated with clinicopathological parameters, disseminated tumour cells in bone marrow (DTC) and clinical outcome. Depending on short allele with <25 and long allele with ≥25, GTn repeats three genotypes (SS, SL and LL) were defined. A diverse role of GTn was evident in squamous cell carcinoma (SCC) and adenocarcinoma (AC). In SCC, the SS genotype presented less advanced tumours with lower rate DTC in bone marrow and relapse compared with L-allele carriers. In contrast, AC patients with the SS genotype displayed a complete opposing tumour characteristic. The disease-free (DFS) and overall survival (OS) in SCC patients was markedly reduced in LL genotypes (p < 0.001). In AC contrarily the SS genotype patients displayed the worst DFS and OS (p < 0.001). GTn is a strong prognostic factor with diverse prognostic value for recurrence and survival in AC and SCC.

Imaging of appendicitis in adults.

UNLABELLED: Three imaging modalities are available for the diagnosis of acute appendicitis: ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). Transabdominal ultrasound should be the first-line imaging test. Abdominal CT is superior to US and is required immediately in patients with atypical clinical presentation of appendicitis and suspected perforation. However, low-dose unenhanced CT is equal to standard-dose CT with intravenous contrast agents in the detection of five signs of acute appendicitis (thickened appendiceal wall more than 2 mm, cross-sectional diameter greater than 6 mm, periappendicitis, abscess, and appendicolith). MRI is necessary in pregnant women and young adults. This review illustrates the principles of state-of-the-art imaging techniques and their clinical relevance. KEY POINTS: • US is the basic diagnostic method in case of suspected appendicitis.• CT is necessary in patients with atypical presentation of appendicitis.• MRI should be the first-line imaging test in pregnant women.

Long term ketamine and ketamine plus alcohol toxicity - what can we learn from animal models?

This review addressed the adverse effects of the frequently-used recreational drug, ketamine through using mice and monkey models. Our laboratory has documented initially that ketamine can induce the formation of hyperphosphorlated tau (hypertau), which is a hallmark of Alzheimer's disease (AD), in the cerebral cortex of both mice and monkeys as well as apoptosis in neurons in these species. Besides the cerebral cortex, other centers in the central nervous system (CNS) and peripheral nervous system (PNS) are also influenced by ketamine. Cerebellum was found to be down-regulated in both mice and humans after long-term of ketamine administration and it was caused by the apoptosis of Purkinje cells. Deleterious effects in other organs reported in long-term ketamine users include of kidney dysfunction leading to proteinuria, fibrosis of the urinary bladder and reduction in size of the urinary bladder leading to frequent urination, increase of liver fibrosis and cardiac problems such as premature ventricular beats. Moreover, ketamine is usually co-administrated with other chemicals such as caffeine or alcohol. It has been reported increased harmful effects when ketamine was used in combination with the above substances. Mechanisms of damages of ketamine might be due to 1) up-regulation of NMDA receptors leading to overestimation of glutamatergic system or 2) the metabolite of ketamine which was a hydroquinone exerted toxicity.

Surgical strategies in patients with advanced hilar cholangiocarcinoma (Klatskin tumor).

BACKGROUND: Surgical resection represents the only potentially curative treatment for hilar cholangicarcinoma. Because of the aggressive nature and the absence of effective adjuvant therapy treatment remains still a challenge. DISCUSSION: This manuscript reviews management of hilar cholangiocarcinoma with a focus on operative strategy.

Extract of white button mushroom affects skin healing and angiogenesis.

White button mushroom extract was examined in this study on (1) its potential effect on angiogenesis in chorioallantoic culture and (2) its recovering effect on the skin after injury in the ICR mice. Methods used included TUNEL assay on apoptosis, immunohistochemistry for vascular endothelial growth factor (VEGF), proliferative cell nuclear antigen (PCNA), epidermal growth factor (EGF), transforming growth factor ß (TGF-ß), and immune factor CD4 and western blotting. The results of chorioallantoic culture showed that the mushroom treatment led to significant increase in densities of VEGF sites. In the skin injury, ICR mice model increased EGF, PCNA, and collagen fibers, along with decrease of TUNEL positive apoptotic cells and limited reaction of TGF-ß and CD4 indicated that white button mushroom extract appeared to have beneficial effects on skin in regeneration and after injury.

Serotonin and its receptors in the human CNS with new findings - a mini review.

Serotonin (5-hydroxytryptamine, 5-HT) is well known to be closely associated with emotional disorders, such as depression and schizophrenia. The seven main members of 5-HT receptor family including the different subtypes are involved in the functional pathways in the brain and their balance in activity helps to maintain the normal mental stability. As any detrimental changes in the 5-HT system is believed to alter emotion in human, different drugs including serotonin reuptake inhibitors (SSRIs) are nowadays commonly used as anti- depressives. In this review, 5-HT(1A) and 5-HT(2A) receptors and serotonergic positive cells in the human were highlighted in particular. It is hoped that this review will give a map of these major 5-HT receptors and serotonergic neurons in the human CNS to facilitate further deciphering of their functions.

Branchial ammonia excretion in the Asian weatherloach Misgurnus anguillicaudatus.

The weatherloach, Misgurnus anguillicaudatus, is a freshwater, facultative air-breathing fish that lives in streams and rice paddy fields, where it may experience drought and/or high environmental ammonia (HEA) conditions. The aim of this study was to determine what roles branchial Na(+)/K(+)-ATPase, H(+)-ATPase, and Rhcg have in ammonia tolerance and how the weatherloach copes with ammonia loading conditions. The loach's high ammonia tolerance was confirmed as was evident from its high 96 h LC(50) value and high tissue tolerance to ammonia. The weatherloach does not appear to make use of Na(+)/NH(4)(+)-ATPase facilitated transport to excrete ammonia when exposed to HEA or to high environmental pH since no changes in activity were observed. Using immunofluorescence microscopy, distinct populations of vacuolar (V)-type H(+)-ATPase and Na(+)/K(+)-ATPase immunoreactive cells were identified in branchial epithelia, with apical and basolateral staining patterns, respectively. Rhesus C glycoprotein (Rhcg1), an ammonia transport protein, immunoreactivity was also found in a similar pattern as H(+)-ATPase. Rhcg1 (Slc42a3) mRNA expression also increased significantly during aerial exposure, although not significantly under ammonia loading conditions. The colocalization of H(+)-ATPase and Rhcg1 to the similar non-Na(+)/K(+)-ATPase immunoreactive cell type would support a role for H(+)-ATPase in ammonia excretion via Rhcg by NH(4)(+) trapping. The importance of gill boundary layer acidification in net ammonia excretion was confirmed in this fish; however, it was not associated with an increase in H(+)-ATPase expression, since tissue activity and protein levels did not increase with high environmental pH and/or HEA. However the V-ATPase inhibitor, bafilomycin, did decrease net ammonia flux whereas other ion transport inhibitors (amiloride, SITS) had no effect. H(+)-ATPase inhibition also resulted in a consequent elevation in plasma ammonia levels and a decrease in the net acid flux. In gill, aerial exposure was also associated with a significant increase in membrane fluidity (or increase in permeability) which would presumably enhance NH(3) permeation through the plasma membrane. Taken together, these results indicate the gill of the weatherloach is responsive to aerial conditions that would aid ammonia excretion.

Late recurrent seminoma: 18 years after bilateral orchidectomy in patient with bilateral stage one testicular seminoma.

Late recurrence of stage I seminoma is an uncommon event. We reported a patient with seminoma recurred 18 years after the initial bilateral orchidectomy for bilateral stage I seminoma. He was on surveillance after the initial treatment and remained disease free for 18 years. He then presented with liver mass and diagnosed as recurrent seminoma. Systemic chemotherapy and subsequent hepatectomy for residual hepatic tumour mass were performed and the disease was cleared. The incidence and management of the late recurrence of seminoma would be discussed.

Pre-existent portal vein thrombosis in liver transplantation: influence of pre-operative disease severity.

BACKGROUND: Portal vein thrombosis (PVT) is a surgical challenge in liver transplantation (LTx). In contrast to LTx in decompensated liver disease, which are associated with a higher morbidity and mortality, PVT influence on outcome is still under debate. To evaluate this influence at different stages of liver decompensation, we compared the outcome of patients suffering from PVT to patients with patent portal vein within different score ranges. METHODS: We included 193 LTx (24 with PVT) in our study, transplanted between 2004 and 2007 at our institution. Patients were divided into four Model of End-Stage Liver Disease (MELD) score groups, and outcome was compared between PVT- and non-PVT patients. RESULTS: In non-decompensated liver disease (MELD <15), we found a significantly decreased survival in patients suffering from PVT (one-yr survival 57% vs. 89%). By contrast, MELD score >15 (decompensated liver disease) leads to an equal or even better survival in PVT-patients compared with patients without PVT (one-yr survival 91% vs.75%), with an only slightly increased morbidity. CONCLUSION: Outcome in patients with PVT seems to be dependent on pre-operative disease severity. In contrast to compensated liver disease, no influence of PVT on outcome could be found in decompensated liver disease, and should therefore not be considered as a contraindication in LTx.

Ammonia transport in cultured gill epithelium of freshwater rainbow trout: the importance of Rhesus glycoproteins and the presence of an apical Na+/NH4+ exchange complex.

The mechanisms of ammonia excretion at fish gills have been studied for decades but details remain unclear, with continuing debate on the relative importance of non-ionic NH(3) or ionic NH(4)(+) permeation by various mechanisms. The presence of an apical Na(+)/NH(4)(+) exchanger has also been controversial. The present study utilized an in vitro cultured gill epithelium (double seeded insert, DSI) of freshwater rainbow trout as a model to investigate these issues. The relationship between basolateral ammonia concentration and efflux to apical freshwater was curvilinear, indicative of a saturable carrier-mediated component (K(m)=66 micromol l(-1)) superimposed on a large diffusive linear component. Pre-exposure to elevated ammonia (2000 micromol l(-1)) and cortisol (1000 ng ml(-1)) had synergistic effects on the ammonia permeability of DSI, with significantly increased Na(+) influx and positive correlations between ammonia efflux and Na(+) uptake. This increase in ammonia permeability was bidirectional. It could not be explained by changes in paracellular permeability as measured by [(3)H]PEG-4000 flux. The mRNA expressions of Rhbg, Rhcg2, H(+)-ATPase and Na(+)/H(+) exchanger-2 (NHE-2) were up-regulated in DSI pre-exposed to ammonia and cortisol, CA-2 mRNA was down-regulated, and transepithelial potential became more negative. Bafilomycin (1 micromol l(-1)), phenamil (10 micromol l(-1)) and 5-(N,N-hexamethylene)amiloride (HMA, 10 micromol l(-1)) applied to the apical solution significantly inhibited ammonia efflux, indicating that H(+)-ATPase, Na(+) channel and NHE-2 pathways on the apical surface were involved in ammonia excretion. Apical amiloride (100 micromol l(-1)) was similarly effective, while basolateral HMA was ineffective. Pre-treatment with apical freshwater low in [Na(+)] caused increases in both Rhcg2 mRNA expression and ammonia efflux without change in paracellular permeability. These data suggest that Rhesus glycoproteins are important for ammonia transport in the freshwater trout gill, and may help to explain in vivo data where plasma ammonia stabilized at 50% below water levels during exposure to high environmental ammonia ( approximately 2300 micromol l(-1)). We propose an apical ;Na(+)/NH(4)(+) exchange complex' consisting of several membrane transporters, while affirming the importance of non-ionic NH(3) diffusion in ammonia excretion across freshwater fish gills.

A cell penetrating heme oxygenase protein protects heart graft against ischemia/reperfusion injury.

Ischemia/reperfusion (I/R) injury is an unavoidable barrier that significantly affects outcome of solid organ transplantation. Here, we establish a protein transduction system to extend graft preservation time and to prevent I/R injury in heart transplantation. We generated a recombinant heme oxygenase-1 (HO-1) protein containing a modified protein transduction domain (PTD). PTD could cross cover cell membrane and carry target molecule to parenchymal cells of cold-preserved heart grafts. The newly generated PTD-HO-1 protein localized mainly in subcellular membrane organelle and nucleus after delivery that significantly prolonged cold preservation of heart grafts. This effect was associated with significantly less endothelial cell activation, less neutrophil and macrophage infiltration in PTD-HO-1-transduced heart grafts after reperfusion as compared with controls. In addition, transduction of PTD-HO-1 protein to heart graft significantly suppressed the I/R injury-associated myocardiocyte apoptosis. The infarct areas of heart graft after I/R injury were significantly reduced after PTD-HO-1 protein treatment. We show here for the first time that PTD can maintain its biological activities during cold preservation. Transduction of cell penetrating HO-1 protein significantly prolongs the cold preservation time and protects the graft from the I/R injury. This approach represents a novel method for the improvement of the overall outcome of organ transplantation.

Contrast harmonic ultrasound and indocyanine-green fluorescence video angiography for evaluation of dermal and subdermal microcirculation in free parascapular flaps.

PURPOSE: Contrast harmonic ultrasound (CHI) with a linear transducer is a new diagnostic approach that allows dynamic and quantitative flow detection of tissue perfusion in microsurgery. The aim of the study was the evaluation of perfusion of the dermal and subdermal layers of microvascular tissue transplants with CHI in comparison to ICG-fluorescence angiography. MATERIAL AND METHOD: In a prospective clinical study Indocyanine-Green Fluorescence Video Angiography and Contrast Enhanced High Resolution Ultrasound (5-10 MHz; linear transducer; Logiq 9; GE) were used for evaluation of the microcirculation in 10 transplanted free parascapular flaps. Two regions were analysed, the centre of the flap and the region of the anastomosis. The perfusion patterns of both methods were compared. RESULTS: The perfusion indexes measured by ICG-fluorescence angiography correlated very precisely in all patients with the quantitative perfusion curves of contrast-enhanced US with CHI. Two flaps with slow filling and low dye intensity showed low contrast enhancement in CHI with modified perfusion curves with slow increase. In two cases a reduced perfusion and filling were found. There were no statistical differences between the two diagnostic methods (p>0.01). CONCLUSION: CHI improves US detections of dermal and subdermal microcirculation in comparison to ICG fluorescence angiography. CHI is a new diagnostic method for postoperative monitoring of free flaps.

Contrast harmonic ultrasound and indocyanine-green fluorescence video angiography for evaluation of dermal and subdermal microcirculation in free parascapular flaps.

PURPOSE: Contrast harmonic ultrasound (CHI) with a linear transducer is a new diagnostic approach that allows dynamic and quantitative flow detection of tissue perfusion in microsurgery. The aim of the study was the evaluation of perfusion of the dermal and subdermal layers of microvascular tissue transplants with CHI in comparison to ICG-fluorescence angiography. MATERIAL AND METHOD: In a prospective clinical study indocyanine-green fluorescence video angiography and contrast enhanced high resolution ultrasound (5-10 MHz; linear transducer; Logiq 9; GE) were used for evaluation of the microcirculation in 10 transplanted free parascapular flaps. Two regions were analysed, the centre of the flap and the region of the anastomosis. The perfusion patterns of both methods were compared. RESULTS: The perfusion indexes measured by ICG-fluorescence angiography correlated very precisely in all patients with the quantitative perfusion curves of contrast-enhanced US with CHI. Two flaps with slow filling and low dye intensity showed low contrast enhancement in CHI with modified perfusion curves with slow increase. In two cases a reduced perfusion and filling were found. There were no statistical differences between the two diagnostic methods (p>0.01). CONCLUSION: CHI improves US detections of dermal and subdermal microcirculation in comparison to ICG fluorescence angiography. CHI is a new diagnostic method for postoperative monitoring of free flaps.