Image Analysis Device Research Articles

Lightweight target shooting image analysis device based on Raspberry Pi

This paper shows a lightweight target image analysis device using Raspberry Pi as the master control, which contains the processing and data analysis of the whole target image, making it easier for the public to perform shooting analysis. System uses Raspberry Pi 4b as the main control, python as the core language, the whole target surface processing is divided into five parts: target ring analysis, bullet point analysis, data processing, data visualization and user interface. The whole system is low-priced, convenient and lightweight, and can be connected to any screen to display the whole shooting process and human-computer interaction. In the test, the system shows excellent recognition accuracy and speed, flexible and simple, and multiple interfaces make the program expansion very accessible. In the subsequent development, it can be combined with deep learning to pool multi-dimensional shooting data as a way to filter out the best shooting groups for subsequent training.

Prediction of air pressure resistance during the ventilation of wood chips as a function of multiple physical fuel parameters

Air pressure resistance during ventilation was measured experimentally for a high variety of conventional wood chip samples that had been produced using various raw materials, chippers and chipper settings (n = 95). Physical fuel properties such as bulk density or particle size distribution were determined according to international standards for solid biofuels. In addition, particle length and particle shape were determined using a continuously measuring image analysis device. Pressure resistance (in Pa m−1) was determined using a custom-built flow cylinder (2 m height, 0.4 m3 filling volume) and related to air flow rate.Pressure resistance increased exponentially with air flow rate for all samples. Thereby, pressure resistance was highly variable among wood chip samples, ranging from 10 to 107 Pa m−1 at low air flow rates (0.1 m3 s−1 m−2) and from 197 to 1240 Pa m−1 at higher air flow rates (0.5 m3 s−1 m−2). Four common equations to describe pressure resistance (Ramsin, Shedd, Hukill & Ives, Ergun) were compared. Multiple linear regression analysis was applied to express pressure resistance as a function of selected fuel quality parameters. Sensitivity analyses of the resulting equations were performed. Results indicate that pressure resistance strongly depends on bulk density, particle size and particle shape as these parameters determine the number, size and shape of free air voids within wood chip fillings.

Analysis of particulate exposure during continuous drug infusion in critically ill adult patients: a preliminary proof-of-concept in vitro study

BackgroundIn critically ill patients, drug incompatibilities frequently occur because of the number of drugs to be administered through a limited number of infusion lines. These are among the main causes of particulate contamination. However, little data is available to quantify particle exposure during simultaneous IV-drug infusion. The objective of this study was to evaluate the particulate matter potentially administered to critically ill patients.MethodsThe particulate matter (between 1 μm and 30 mm) of infused therapies used in ICUs for patients suffering from either septic shock or acute respiratory distress syndrome was measured in vitro over 6 h using a dynamic image analysis device, so that both overall particulate contamination and particle sizes could be determined. Data is presented according to the recommendations of the European Pharmacopoeia (≥ 10 and 25 μm).ResultsFor the six experimental procedures (continuous infusion of norepinephrine, midazolam, sufentanil, heparin, 5% glucose, binary parenteral nutrition and discontinuous administrations of omeprazole, piperacillin/tazobactam and fluconazole), the overall number of particles over the 6-h infusion period was 8256 [5013; 15,044]. The collected values for the number of particles ≥ 10 and 25 μm were 281 [118; 526] and 19 [7; 96] respectively. Our results showed that discontinuous administrations of drugs led to disturbances in particulate contamination.ConclusionsThis work indicates the amount of particulate matter potentially administered to critically ill adult patients. Particulate contamination appears lower than previous measurements performed during multidrug IV therapies in children.

Multicenter Evaluation of an Image Analysis Device (APAS): Comparison Between Digital Image and Traditional Plate Reading Using Urine Cultures.

BackgroundThe application of image analysis technologies for the interpretation of microbiological cultures is evolving rapidly. The primary aim of this study was to establish whether the image analysis system named Automated Plate Assessment System (APAS; LBT Innovations Ltd., Australia) could be applied to screen urine cultures. A secondary aim was to evaluate differences between traditional plate reading (TPR) and the reading of cultures from images, or digital plate reading (DPR).MethodsA total of 9,224 urine samples submitted for culture to three clinical laboratories, two in Australia and one in the USA, were included in the study. Cultures were prepared on sheep blood and MacConkey agar plates and read by panels of three microbiologists. The plates were then presented to APAS for image capture and analysis, and the images and results were stored for later review.ResultsImage analysis of cultures using APAS produced a diagnostic sensitivity and specificity of 99.0% and 84.5%, respectively. Colonies were detected by APAS on 99.0% of blood agar plates with growth and on 99.5% of MacConkey agar plates. DPR agreed with TPR for colony enumeration on 92.1% of the plates, with a sensitivity of 90.8% and specificity of 92.8% for case designation. However, several differences in the classification of colony morphologies using DPR were identified.ConclusionsAPAS was shown to be a reliable screening system for urine cultures. The study also showed acceptable concordance between DPR and TPR for colony detection, enumeration, and case designation.

No proof for the best instrumented device to grade the pivot shift test: a systematic review

Background The pivot shift test has been representing the current benchmark in the assessment of dynamic knee laxity related to anterior cruciate ligament injury. Recently, clinical evaluation has been supported by the use of several technologies able to quantify the joint kinematics during the test. Objective The main aim of this review was to verify whether the clinical evaluation of dynamic knee laxity can be supported by a standardised instrumented assessment of the pivot shift test, reported in high-quality clinical trials. Data sources Internet search was performed on PubMed database, Web of Science and reference on published manuscripts. Study eligibility criteria No year restriction was used. Articles were included only when written in English and related to search terms (‘pivot shift’ AND ‘assessment’). 3 reviewers independently selected only in vivo studies that reported both the clinical and quantitative assessment of the pivot shift test. Those articles that analysed only clinical parameters were excluded. Synthesis methods Reviewers evaluated the methodological quality of the studies and extracted the data using a defined protocol. Studies were summarised in terms of demographics, methodologies and technologies used to quantify the pivot shift, clinical grading and any reported correlation or statistical difference between the clinical assessment and the instrumented one. Results 9 studies met the inclusion criteria. The literature presented several devices able to quantify the clinical manoeuvre, specifically the electromagnetic system (2 studies), inertial sensors (6 studies) and image analysis device (1 study). Although mainly used by experts, the most widespread methods (7 out of 9 studies) were reported to be those able to quantify the tibial acceleration. Limitations The study results were extremely heterogeneous. Intertester variability in clinical grading limited the possibility of using it to coherently validate the proposed methodologies. However, no ‘gold standard’ methodology for the evaluation of the pivot shift has been established within the clinical context. Conclusions and relevance A standardised methodology and approach for the quantification of the pivot shift, supported by the highest clinical evidence, is still lacking. It is fundamental to define high-quality randomised perspective clinical trials, thus to allow to reach a proper ‘benchmark’ in the assessment of dynamic knee laxity.

Delayed fluorescence, steady state fluorescence, photosystem II quantum yield as endpoints for toxicity evaluation of Cu2+ and Ag+

The effect of copper and silver ions on photosynthetic parameters of the flagellate Euglena gracilis was determined. The photosystem II quantum yield (Y(PSII)) and steady state fluorescence (Ft) were measured with a PAM-fluorometer, while delayed fluorescence (DF) was determined by means of a sensitive single-photon camera attached to an image analysis device, which counted the relative number of photons released from the algae in darkness after previous light-stimulation. We found that after 3h of incubation photosynthesis was affected only in the presence of relatively high concentrations of the used noble metals. The obtained EC50 values for Cu2+ were 505.8mgL−1 (Y (PSII)), 286.5mgL−1 (DF), and 491.0mgL−1 (Ft). The EC50 values for silver ions were 51.9mgL−1 (Y (PSII)), 51.8mgL−1 (DF) (values for Ft not determinable). Photosynthesis is far less sensitive against toxic noble metals compared to motility parameters as reported in earlier studies, in part because the organelles of photosynthesis, the chloroplasts, are well protected from external substances within the cell, while flagella, reaching into the surrounding of the cell, are more easily influenced. As chloroplasts are easily accessible by means of non-invasive methods e.g. PAM- fluorometry, they are probably interesting model systems in order to detect effects of substances deep inside the cell. Influence on the chloroplasts is a measure that a germicide entered the cells, diffused through the cytoplasm and the membranous systems and reached compartmentalized enzyme complexes.

Evaluation of an Image Analysis Device (APAS) for Screening Urine Cultures.

While advancements have been made in some areas of pathology with diagnostic materials being screened using image analysis technologies, the reporting of cultures from agar plates remains a manual process. We compared the results for 2,163 urine cultures read by a reference panel of microbiologists, by the routine laboratory process, and by an automated plate reading system, APAS (LBT Innovations Ltd., South Australia). APAS detected colonies with a sensitivity of 99.1% and a specificity of 99.3% on blood agar, while on MacConkey agar, the colony detection sensitivity was 99.4% with a specificity of 99.3%. The device's ability to enumerate growth had an accuracy of 89.2%, and the morphological identification of colonies showed a high level of performance for the colony types typical of Escherichia coli and other enteric bacilli. On blood agar, lactose-fermenting colonies were morphologically identified with a sensitivity of 98.9%, while on MacConkey agar they were identified with a sensitivity of 99.2%. In this first clinical evaluation, APAS demonstrated high performance in the detection, enumeration, and colony classification of isolates compared with that for conventional plate-reading methods. The device found all cases reported by the laboratory and detected the most commonly encountered organisms found in urinary tract infections.

AG-MIC: Azure-Based Generalized Flow for Medical Image Classification

Medical image-based research requires heavy computational workload associated with image analysis and collaborative device independent platforms to incorporate expert opinions from multiple institutions. Cloud-based resources such as Microsoft Azure Machine Learning Studio (MAMLS) provide such a platform that is conducive to the medical-image-based data analysis. This paper fosters the advantages of the cloud-based computing frameworks (such as MAMLS) and presents a practical work-flow well-suited for the standard machine learning tasks seen in medical image research viz., binary classification, multi-class learning, regression and so on. The proposed automated generalized workflow allows medical researchers/practitioners to focus on data inferencing rather than dealing with the intricate details of predictive modeling, such as feature and model selection. The scalable architecture of the proposed flow utilizes the MAMLS framework to processes data sets that require partial core storage space in the virtual machine to one complete core storage space in a common flow. Also, the proposed flow invokes multiple feature ranking and predictive models in parallel for automated selection and parameterization of the optimal data model. The performance of the proposed flow is bench-marked on 14 public data sets and four local medical image data sets (~0.12 MB–1.22 GB) using a single common flow, while ensuring better (~ 8% improvement) or atleast similar generalization capability with respect to existing works.

Characterisation of unbound aggregate materials considering physical and morphological properties

The objective of this paper is to evaluate the factors affecting resilient and permanent deformation behaviour of unbound granular materials, with a focus on the aggregate physical and morphological characteristics. To evaluate the behaviour of base course, repeated load triaxial testing is commonly used to establish the stress-dependent resilient modulus properties of unbound aggregate base and subbase materials. Although resilient modulus of aggregates is a critical input into mechanistic-empirical pavement design methods, the resilient modulus of unbound base material is often estimated from empirical correlations with index properties in the AASHTOWare Pavement ME design procedure for its simplicity. Since actual field stress conditions and resilient modulus stress states are generally quite different from those generated in the empirical test methods, use of an empirical correlation could lead to an unreliable prediction of resilient modulus and permanent deformation. In order to properly assess the stability of an unbound aggregate layer, it is necessary to establish a proper process to understand the factors affecting fundamental and performance-related properties of unbound granular materials. In this study, aggregate samples from four different sources were tested for resilient modulus and Poisson’s ratio measurements using the Precision Unbound Material Analyzer equipment. Morphological or shape properties of aggregate samples were also measured using an image analysis device. The results demonstrate that aggregate physical and morphological properties affect aggregate resilient and permanent deformation. Further, it is suggested that the resilient modulus of the aggregate should not be used as the sole indicator of rutting performance of aggregate base.

The effect of raw material and machine setting on chipping performance and fuel quality – a German case study

Fuel qualities of wood chips and energy consumption during their production vary depending on raw materials and machine settings. Thereby, requirements for small combustion units <1 MW are rarely met. Therefore, the effects of raw material and machine settings on chipping performance were investigated in numerous field trials (n = 34). Raw materials were derived from different tree parts of various species (forest residues and “energy round wood,” i.e. small-sized delimbed stem wood). Chipper settings varied in knife sharpness, screen size and discharge systems. All samples were analyzed following European standards. In addition, particle size distribution and particle shape were analyzed using a continuously measuring image analysis device. Classification followed ISO standards 17225-1 and 17225-4. Fuel consumption during chipping was measured and related to volume and weight of the bulk material. Ash content of wood chips ranged from 0.4–1.7 weight.-% (w.-% dry basis) for energy round wood and from 1.0–5.4 w.-% for forest residues. Particle size distribution of all samples could be classified according to ISO 17225-1 but only 30% could be classified according to ISO 17225-4. These requirements were often met when using energy round wood and sharp knives. Moreover, particle shape strongly related to knife sharpness. Specific fuel consumption during chipping ranged from 0.17–0.70 litres per m3 bulk volume and was high for forest residues, small screen sizes or blunt knives. Overall energy consumption of the chipping process was <1% of the energy stored within the produced bulk material.

Leukoaraiosis is associated with arterial wall thickness: A quantitative analysis

Leukoaraiosis refers to an age-related, abnormal appearance of the brain white matter on neuroimaging. The association between leukoaraiosis and cerebrovascular disease suggests that ischemia may be an important contributing factor; however, the pathogenesis of the condition remains controversial. We hypothesized that physical abnormalities of blood vessels might be culpable and compared the external and internal measurements of blood vessel walls between brains that demonstrated leukoaraiosis on imaging and normal control brains. Fourteen brains of individuals who had been diagnosed as having severe leukoaraiosis and five non-leukoaraiosis control brains were studied. Arterial cross-sections were evaluated by length measurements with an image analysis device. Arterial wall thickness and the ratio of the outer and inner diameters of the vessel were measured. We measured a total of 108 vessels in the leukoaraiosis group and 95 vessels in the control group. The vessel walls of the leukoaraiosis patients were an average of 5.5 µm thicker than the walls of control vessels of the same inside diameter (P = 0.0000, 95% CI 3.01-8.08) and an average of 2.3 µm thicker than walls of control vessels of the same outside diameter (P = 0.016, 95% CI 0.48-4.17). Our data provide evidence that leukoaraiosis is associated with vessel wall thickening in an additive fashion and indicate that structural vascular abnormalities are associated with leukoaraiosis.

QTL analysis of seed germination and pre-emergence growth at extreme temperatures in Medicago truncatula

Enhancing the knowledge on the genetic basis of germination and heterotrophic growth at extreme temperatures is of major importance for improving crop establishment. A quantitative trait loci (QTL) analysis was carried out at sub- and supra-optimal temperatures at these early stages in the model Legume Medicago truncatula. On the basis of an ecophysiological model framework, two populations of recombinant inbred lines were chosen for the contrasting behaviours of parental lines: LR5 at sub-optimal temperatures (5 or 10°C) and LR4 at a supra-optimal temperature (20°C). Seed masses were measured in all lines. For LR5, germination rates and hypocotyl growth were measured by hand, whereas for LR4, imbibition and germination rates as well as early embryonic axis growth were measured using an automated image capture and analysis device. QTLs were found for all traits. The phenotyping framework we defined for measuring variables, distinguished stages and enabled identification of distinct QTLs for seed mass (chromosomes 1, 5, 7 and 8), imbibition (chromosome 4), germination (chromosomes 3, 5, 7 and 8) and heterotrophic growth (chromosomes 1, 2, 3 and 8). The three QTL identified for hypocotyl length at sub-optimal temperature explained the largest part of the phenotypic variation (60% together). One digenic interaction was found for hypocotyl width at sub-optimal temperature and the loci involved were linked to additive QTLs for hypocotyl elongation at low temperature. Together with working on a model plant, this approach facilitated the identification of genes specific to each stage that could provide reliable markers for assisting selection and improving crop establishment. With this aim in view, an initial set of putative candidate genes was identified in the light of the role of abscissic acid/gibberellin balance in regulating germination at high temperatures (e.g. ABI4, ABI5), the molecular cascade in response to cold stress (e.g. CBF1, ICE1) and hypotheses on changes in cell elongation (e.g. GASA1, AtEXPA11) with changes in temperatures based on studies at the whole plant scale.

Effect of fundus image devices for early diagnosis of primary open angle glaucoma

Evaluation of the optic disc and retinal nerve fiber layer measurements (RNFL) with stereophotography is the current "gold standard" for the diagnosis of early primary open angle glaucoma (POAG), but it is still subjective and is dependent too much upon an experienced observer. Substantial variability exists in the interpretation of optic disc change over time. There are consistent evidences that image analysis devices such as optical coherence tomography (OCT) and Heidelberg retina tomograph (HRT-II) can detect early to moderate glaucoma as well as expert assessment of stereoscopic optic disc and RNFL photographs. Optic disc and RNFL defect can be quantitatively measured by these devices. But the sensitivity and specificity of the measurements obtained with these devices are not good enough for the early diagnosis of POAG at this time due to several reasons, such as individual variety of the structure parameters in normal subjects, lack of powerful normative database, lack of diagnostic parameters which are good enough both in sensitivity and specificity for detecting early glaucoma damage. However, information obtained from these image analysis devices might be helpful in early POAG diagnosis if clinicians can understand the advantages and limitations of these instruments.

A methodological approach for direct quantification of the activated sludge floc size distribution by using different techniques

The activated sludge floc size distribution (FSD) is investigated by using different measurement techniques in order to gain insight in FSD assessment as well as to detect the strengths and limitations of each technique. A second objective was to determine the experimental conditions that allow a representative and accurate measurement of activated sludge floc size distributions. Laser diffraction, Time Of Transition (TOT) and Dynamic Image Analysis (DIA) devices were connected in series. The sample dilution liquid, the dilution factor and hydraulic flow conditions avoiding flocculation proved to be important. All methods had certain advantages and limitations. The MastersizerS has a broader dynamic size range and provides accurate results at high concentrations. However, it suffers from an imprecise evaluation of small size flocs and is susceptible to particle shape effects. TOT suffers less from size overestimation for non-spherical particles. However, care should be taken with the settings of the transparency check. Being primarily a counting technique, DIA suffers from a limited size detection range but is an excellent technique for process visualization. All evaluated techniques turned out to be reliable methods to quantify the floc size distribution. Selection of a certain method depends on the purpose of the measurement.

A signature predictive of disease outcome in breast carcinomas, identified by quantitative immunocytochemical assays

Quantitative immunocytochemical assays of 1,200 breast carcinomas were assessed after construction of tissue microarrays. A total of 42 markers were evaluated for prognostic significance by univariate log rank test (mean follow-up, 79 months), using quantitative scoring by an image analysis device and specific software. Complete data were obtained for 924 patients, for whom 27 of the 42 markers proved to be significant prognostic indicators. Analysis of these 27 markers by logistic regression showed that 18 (cMet, CD44v6, FAK, moesin, caveolin, c-Kit, CK14, CD10, P21, P27, pMAPK, pSTAT3, STAT1, SHARP2, FYN, ER, PgR and c-erb B2), and 15 when ER, PgR and c-erb B2 were excluded, were 80.52% and 78.9% predictive of disease outcome, respectively. The immunocytochemical assays on 4 micron thick sections of fixed tissue are easy to handle in current practice and are cost-effective. Quantitative densitometric measurement of immunoprecipitates by computer-assisted devices from digitized microscopic images allows standardized high-throughput "in situ" molecular profiling within tumors. It is concluded that this 15 marker immunohistochemical signature is suitable for current practice, since performed on paraffin sections of fixed tumor samples, and can be used to select patients needing more aggressive therapy, since this signature is about 80% predictive of poor clinical outcome. Also, the markers included in the signature may be indicative of tumor responsiveness to current chemotherapy or suggest new targets for specific therapies.

La lecture automatisée à haut débit des micro-biopsies en pathologie : mise en évidence de la surexpression de c-Met et PI3K dans les cancers du sein inflammatoire

Inflammatory breast carcinoma (IBC) is a rare but very aggressive tumour phenotype. Increased c-Met protein expression correlates with reduced survival and a higher metastatic risk in many human malignancies, including breast cancer Several studies have shown that c-Met protein is targetable by specific drugs. Here we compared c-Met expression in IBC (n = 41) and non IBC (n = 480). Two microarrays of IBC and non IBC tissues were constructed and standardized. C-Met, P13K and E-cadherin were immunodetected (Ven-tana Benchmark Autostainer) on serial sections. The results were quantified with an automated image analysis device (SAMBA Technologies) by immunoprecipitate densitometry of each core section (0.6 microns thick). We found that (i) c-Met is significantly overexpressed in IBC compared to non IBC (p < 0. 001), (ii) P13K is also overexpressed (p < 0.001) in IBC, suggesting that overexpressed c-Met is functionally active, at least through the PI3K signal transduction pathway ; and (iii) E-cadherin is paradoxically overexpressed in IBC. We conclude that c-Met may constitute a target for specific therapy in patients with poor-prognosis malignancies like IBC Automated image analysis of TMA is a valuable tool for high-throughput quantification of the immunohistochemical expression of the tumor proteome.

C-Met overexpression in inflammatory breast carcinomas: automated quantification on tissue microarrays

Inflammatory breast carcinoma (IBC) is a rare but aggressive tumour associated with poor outcome owing to early metastases. Increased expression of c-Met protein correlates with reduced survival and high metastatic risk in human cancers including breast carcinomas and is targetable by specific drugs, that could potentially improve the prognosis. In the present study, we compared c-Met expression in IBC (n=41) and non-IBC (n=480) immunohistochemically (Ventana Benchmark autostainer) in two tissue microarrays (TMA) along with PI3K and E-cadherin. The results were quantified through an automated image analysis device (SAMBA Technologies). We observed that (i) c-Met was significantly overexpressed in IBC as compared with non-IBC (P<0.001), (ii) PI3K was overexpressed (P<0.001) in IBC, suggesting that the overexpressed c-Met is functionally active at least through the PI3K signal transduction pathway; and (iii) E-cadherin was paradoxically also overexpressed in IBC. We concluded that overexpressed c-Met in IBC constitutes a potential target for specific therapy for the management of patients with poor-outcome tumours such as IBC. Automated image analysis of TMA proved to be a valuable tool for high-throughput immunohistochemical quantification of the expression of intratumorous protein markers.

Methods for size classification of wood chips

Abstract Methods for size classification of wood chips were analysed in an international round robin using 13 conventional wood chip samples and two specially prepared standard samples, one from wood chips and one from hog fuel. The true size distribution of these two samples (according to length, width and height) had been determined stereometrically (reference method) using a digital calliper gauge and by weighing each of the about 7000 wood particles per sample. Five different horizontal and three rotary screening devices were tested using five different screen hole diameters (3.15, 8, 16, 45, 63 mm, round holes). These systems are compared to a commercially available continuously measuring image analysis equipment. The results show that among the devices of a measuring principle—horizontal and rotary screening—the results are quite comparable, while there is a severe incompatibility when distributions are determined by different measuring principles. Highest conformity with the reference values is given for measurements with an image analysis system, whereas for all machines with horizontal screens the median value of the size distribution only reached between one-third to half of the reference median value for the particle length distribution. These deviations can be attributed to a higher particle misplacement, which is particularly found in the larger fractions. Such differences decrease when the particle's shape is more roundish (i.e. sphericity closer to one). The median values of length distributions from screenings with a rotary classifier are between the measurements from an image analysis and horizontal screening devices.

Rythmes d'activité locomotrice chez deux insectes parasitoïdes sympatriques : Eupelmus orientalis et Eupelmus vuilleti (Hyménoptère, Eupelmidae)

With an automatic image analysis device, we studied the temporal distribution of the locomotor activity of E. orientalis and E. vuilleti during 24 h, and over several days to know whether the activity rhythms of these two Eupelmidae play a role in their competitive interactions. The analysis of locomotor activity rhythms of E. orientalis and E. vuilleti shows that the locomotor activity of both species presents daily cyclic variations. These two Eupelmidae have similar activity rhythms. Displacements of these parasitoids essentially take place during the photophase. But the activity of E. vuilleti is earlier, because the individuals of this species start their activity on average 4 to 5 h earlier than those of E. orientalis. E. vuilleti begins its displacements several hours before the onset of lighting, whereas E. orientalis is active only in the presence of the light. This shift of starting activity is thus a factor allowing these concurrent species to minimize their interactions during the cohabitation period in traditional granaries after the harvests of cowpea. To cite this article: A. Ndoutoume-Ndong et al., C. R. Biologies 329 (2006).

Different patterns of aerenchyma formation in two hygrophytic species of Paspalum (Poaceae) as response to flooding

Paspalum modestum and P. wrightii are perennial grasses growing in permanent and seasonally flooded areas, respectively. The former produces short rhizomes and floating culms, the latter forms long rhizomes and erect culms. Variations in percentage aerenchymatous space (PAS) in different organs as a response to flooding was analysed using a clone of each species. Eighteen plantlets of each clone were cultivated during 7 months under flooded vs. unflooded conditions. After this period, roots, rhizomes, culms, and leaf sheaths were collected and prepared. PAS was measured using an image analysis device, and data were analysed using ANOVA. Production of aerenchyma took place in both species within the cortical parenchyma of roots, rhizomes and culms, and the mesophyll of leaf sheaths, both in flooded and unflooded plants. Under flooding conditions PAS increased in both species, although the individual response of organs differed: whereas in P. modestum PAS increased primarily in substratum-fixed roots, in P. wrightii all organs produced additional aerenchyma uniformly. Contrasting responses are understood as adaptations to permanent and seasonal flooding, respectively.