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At least 667 records · Page 37Linked to original sources

PubMed1990

Quantitative exercise thallium-201 single photon emission computed tomography for the enhanced diagnosis of ischemic heart disease.

The clinical utility of exercise thallium-201 single photon emission computed tomography was investigated in 360 consecutive patients who had concomitant coronary arteriography. Tomographic images were assessed visually and from computer-quantified polar maps. Sensitivity for detecting coronary artery disease was comparably high using quantitative and visual analysis, although specificity tended to improve using the former method (87% versus 76%, p = 0.09). Quantitative analysis was superior to the visual method for identifying left anterior descending (81% versus 68%, p less than 0.05) and circumflex coronary artery (77% versus 60%, p less than 0.05) stenoses and detected most patients (92%) with multivessel coronary artery disease. Multivessel involvement was correctly predicted in 65% of the patients with more than one critically stenosed vessel. Exercise variables in patients with significant coronary artery disease were similar whether the tomographic images were normal or abnormal. However, patients with coronary stenoses and normal versus abnormal tomograms had a trend toward more single vessel disease (79% versus 62%, p = 0.07) and moderate coronary stenosis (66% versus 28%, p less than 0.001), but had less proximal left anterior descending artery involvement (8% versus 34%, p = 0.05). Computer-quantified perfusion defect size was directly related to the extent of coronary artery disease. Intra- and interobserver agreement for quantifying defects were excellent (r = 0.98 and 0.97, respectively). In conclusion, quantitative thallium-201 tomography offers improved detection of coronary artery disease, localization of the anatomic site of coronary stenosis, prediction of multivessel involvement and accurate determination of perfusion defect size, while maintaining a high specificity. Quantification of perfusion defects with single photon tomography may become important for assessing the effects of coronary reperfusion and prognostically stratifying patients with coronary artery disease.

Aged↗

PubMedDate not supplied

Travel vision: "collicular visual system"?

Two visually impaired children with occipital infarctions are presented. One patient has profound impairment of his primary visual pathway but has good vision for traveling, while the other child presented with the symptoms in reverse. We believe that these two patients provide further evidence that the primary visual pathway is used for conscious visual analysis and that the collicular visual system serves as the subconscious visual guidance for locomotion.

Attention↗

PubMed1997

Enlarged spectrum of seminological diagnoses using the resazurin colour reaction; a spectrophotometric application.

Two sets of investigations were carried out in the present study to establish whether, in semen samples processed for the resazurin reaction (RT), the colour change and its intensity were informative for both the quality and quantity of spermatozoa. First, the results of RT were read visually using single semen samples from 42 consecutive men from infertile couples. In the second step, the results were additionally read using a spectrophotometer. Single semen samples obtained from another 87 consecutive men from infertile couples and 12 men from fertile couples were analysed in this step. Visual analysis, which involved grading against and RT colour chart, revealed a significant positive correlation between the RT results and the quantity and quality of spermatozoa. Azoospermia was diagnosed by grade number 1 (dark purple colour), while the highest grades 8-11 (colours dark red to pink) represented a homogeneous group of patients with the highest quality of spermatozoa (> 60% motility) and quantity (> 60 x 10(6)/ml ejaculate). Normal parameters of spermatozoa, according to WHO, appeared with a high predominance (89-100% of cases) in this group and were present in most of the samples. Thus, the grades 8-11 might represent semen samples with optimal fertility potential. Spectrophotometric analysis of RT revealed that visual characteristics corresponded closely to the values for optical density (OD) of the samples. The OD for normozoospermic samples ranged between 1.48 and 1.84; for oligozoospermia between 1.2 and 1.48; for azoospermia between 0.98 and 1.1. The OD for samples with putative optimal fertility potential ranged between 1.6 and 1.84. RT evaluation using a spectrophotometer may therefore provide a tool for obtaining a wider spectrum of seminological diagnoses than classic microscopic examination, especially for distinguishing men with probable optimal fertility potential.

Adult↗

PubMed2003

Are the results of the Beery-Buktenica Developmental Test of Visual-Motor Integration and its subtests related to achievement test scores?

PURPOSE: Although visual analysis, motor coordination, and visual-motor integration can each affect performance on a test of visual motor integration, previous studies have not reported the relative importance of these components to the relation between visual motor integration and learning readiness, reading, and math. This investigation relates academic achievement in reading and math to performance on the Beery-Buktenica Developmental Test of Visual-Motor Integration (VMI) and its subtests, Visual Perception and Motor Coordination. METHODS: The VMI was administered to 155 children in second through fourth grades (7 to 10 years of age; mean, 8.4 +/- 1.0 years). The Otis-Lennon School Ability Test and Stanford Achievement Test were administered by the school. RESULTS: A significant difference was found in performance on the VMI and Visual Perception and Motor Coordination subtests between children in the upper and lower quartiles in reading (p = 0.020, p < 0.001, and p = 0.027, respectively) and math achievement (p = 0.004, p < 0.001, and p = 0.01, respectively). The VMI standard score was significantly correlated with Stanford total math standard score (p = 0.001) and a trend toward significance was found for Stanford reading score (p = 0.050) while partially controlling for verbal school ability and age. In addition, Visual Perception and Motor Coordination standard scores were significantly related to Stanford math (p < 0.001 and p = 0.005, respectively) and reading score (p = 0.008 and p = 0.027, respectively) after partially controlling for verbal school ability and age. Multiple linear regressions controlling for performance on the VMI and each subtest, as well as age and verbal cognitive ability, showed a significant relation between the Visual Perception subtest score and math achievement. CONCLUSION: Visual perceptual ability should be assessed in children with poor math and/or reading achievement.

Achievement↗

PubMed2005

Entropy and oligomerization in GPCRs.

Evolutionary trace (ET) and entropy are two related methods for analyzing a multiple sequence alignment to determine functionally important residues in proteins. In this article, these methods have been enhanced with a view to reinvestigate the issue ofGPCR dimerization and oligomerization. In particular, cluster analysis has replaced the subjective visual analysis element of the original ET method. Previous applications of the ET method predicted two dimerization interfaces on the external transmembrane lipid-facing region of GPCRs; these were discussed in terms of dimerization and linear oligomers. Removing the subjective element of the ET method gives rise to the prediction of functionally important residues on the external face of each transmembrane helix for a large number of class A GPCRs. These results are consistent with a growing body of experimental information that, taken over many receptor subtypes, has implicated each transmembrane helix in dimeric interactions. In this application, entropy gave superior results to those obtained from the ET method in that its use gives rise to higher z-scores and fewer instances of z-scores below 3.

Animals↗

PubMedDate not supplied

Ultrasmall superparamagnetic iron oxide particles (AMI 227) as a blood pool contrast agent for MR angiography: experimental study in rabbits.

The purpose of this study was to evaluate the contribution of an ultrasmall superparamagnetic iron oxide particles (USPIOs) based contrast agent (AMI 227), in a transverse three-dimensional time-of-flight TONE MR angiography sequence of abdominal aorta in rabbits. The main goal was to assess improvement in the visualization of small arteries such as renal arteries, when using such a sequence. Imaging experiments were performed on a 1.5 T magnet, using a transverse 3D time-of-flight (TOF) tilted optimized nonsaturating excitation (TONE) sequence with magnetization transfer suppression. The contrast media used were composed of a USPIO core surrounded by a dextran-surfactant (AMI 227). Different concentrations of AMI 227 were evaluated in 12 rabbits. Concentrations varied within the range 8.5-34 micromol Fe/kg - bw: 8.5 micromol Fe/kg (three rabbits); 17 micromol Fe/kg (three rabbits); 25.5 micromol Fe/kg (three rabbits); 34 micromol Fe/kg (three rabbits). A visual analysis based on the improvement of visualization of small arteries (renal arteries) on MIP images and a quantitative analysis based on the percentage of contrast enhancement of the aorta plotted against distance in the slab from the top edge of the acquisition volume were obtained. A signal-to-noise ratio enhancement of the distal part of the aorta and only improvement in the delineation of the renal arteries were noted when using low concentrations of the contrast media. A loss of signal-to-noise ratio of the aorta and a decrease in arterial visualization were respectively noted with higher concentration of contrast media. In this experimental study, using a transverse three-dimensional TOF TONE MR angiography sequence of renal arteries, in which sequence the saturation effect is minimized, the use of AMI 227 allows only improvement in the delineation of small arteries when using low concentrations of contrast media.

Animals↗

PubMed1992

[Maximum entropy method and Fourier transform for wave analysis of pattern visual evoked potentials].

To estimate spectral analysis of pattern visual evoked potentials (P-VEPs) the maximum entropy method (MEM) and fast Fourier transform (FFT) were investigated. P-VEPs were recorded in 16 normal eyes using the reversal pattern of 2 c/d vertical sine wave gratings. Six temporal frequencies (2, 3, 4, 6, 8, 12 Hz) were used. MEM power spectrum with the parameter (dimension of autoregression model) which was decided final prediction error (FPE) method did not necessarily always give satisfactory results. The MEM power spectrum of transient VEP changed in manner different from that of steady state VEP as the dimension of autoregression model varied. In steady state VEP the peak of the MEM spectrum was positioned accurately at dimension 50 but in transient VEP the peak positioned accurately at a larger dimension. Both in MEM and FFT the curves of the square root of the power vs temporal frequency resembled each other and had temporal tuning with a maximum at 6 Hz. At lower temporal frequencies (2, 3 Hz) the correlation coefficient increased gradually as the harmonic component became higher (2 nd less than 4 th less than 6 h). MEM powers in the second harmonic component were highly correlated with FFT power in temporal frequency above 4Hz. These results showed that the MEM power spectrum had higher resolution than FFT and had different properties especially at lower temporal frequencies. MEM with optimum parameters should be very useful for wave analysis of P-VEPs.

Evoked Potentials, Visual↗

PubMed1996

Reproducibility of the Conconi test: test repeatability and observer variations.

The repeatability of the the speed/heart rate (S/HR) relationship obtained with the incremental test developed by Conconi et al. (5) was examined by having 75 subjects perform the same running test twice in the course of a few days. From the data obtained, comparisons were made of four variables: 1) speed of deflection, 2) heart rate of deflection, 3) slope, and 4) intercept on the y-axis of the linear portion of the S/HR relationship. Straight-line equations, correlation coefficients (r), and technical errors of measurement (TEM) were obtained by comparing data from the two successive tests. Data analysis suggests that in two successive tests there are some variations in the linear portion of the S/HR relationship. However, the straight lines obtained from the two tests converge at the same deflection point. The problem of assigning a single value to the point of deflection, when determined by means of visual analysis of the S/HR graph, was also examined. For this part of the study, speed and heart rate data previously obtained for 65 subjects were used. The selected tests had been carried out during the course of various studies. The 65 sets of test data were plotted on graph paper and given to six observers for independent evaluation of speed and heart rate of deflection. These observers had different levels of experience in interpreting Conconi test results. The speed and heart rate of deflection values assigned by each observer were compared to the values obtained through mathematical analysis of the tests by computer. Straight-line equations, correlation coefficients (r), and technical errors of measurement (TEM) obtained by comparing visually determined data to those determined through mathematical analysis were calculated for each observer. Only for observers with little experience were some differences found between the observer-assigned and computer-determined results; these differences occurred for both speed and heart rate of deflection. We conclude that visual analysis provides information that is very similar to that obtained through computer analysis. The accuracy of the visually obtained information varies according to the observer's experience.

Adult↗

PubMed1997

[Possibilities and limits of computer-assisted cardiotocogram analysis].

The interpretation of cardiotocograms still relies primarily on visual analysis. This form of monitoring remains labour intensive and, being dependent on the training and experience of the specialist responsible, also subject to erroneous interpretation. Computer-aided cardiotocogram analysis has, in spite of encouraging successes, still not found wide application in everyday clinical routine. To achieve this, the programming system must be easy to operate, userfriendly and reliable. A program system for fully automatic cardiotocogram analysis is envisioned which runs on standard commercially-available personal computers. A clear graphic representation of the traces also permits visual assessment on the computer screen. The system described integrates the main assessment criteria of cardiotocogram analysis which can then be extended owing to the open system architecture used in the programming. Completely new analysis algorithms have given the evaluating system the capability of fully-automatic pattern recognition of fetal heart rate signals and uterine motility. An essential requirement of computer-aided cardiotocogram analysis is thereby fulfilled. Work is now focusing on the exact classification of the various types of deceleration and an extension of the capabilities of tocogram analysis. There should be nothing to hinder integration of the system into everyday clinical routine and connect it to obstetrical databases.

Algorithms↗

PubMed1996

Technetium-99m-sestamibi SPECT to detect restenosis after successful percutaneous coronary angioplasty.

UNLABELLED: This study evaluated the accuracy of 99mTc SPECT in predicting restenosis after primary successful PTCA. METHODS: Thirty-seven patients with equivocal symptom-limited exercise stress testing were evaluated. All patients underwent separate day exercise-rest 99mTc-sestamibi SPECT. The perfusion studies were evaluated using three different methods of analysis: visual inspection, semiquantitative and quantitative polar map analysis. The perfusion studies were interpreted in absence of a pre-PTCA scan. All patients underwent a control coronary angiography within 1 mo. RESULTS: Sensitivity and specificity of 99mTc-sestamibi SPECT in predicting restenosis were 87.5-78%, 50-65% and 75-74% for visual inspection, semiquantitative and quantitative polar map analysis, respectively. Sensitivity and specificity related to the vascular territories were: LAD territory 93-73% (qualitative analysis), 53-60% (semiquantitative analysis), 80-67% (quantitative analysis); LCX territory 83-100% (qualitative analysis); and 33-100% (semiquantitative analysis), 67-100% (quantitative analysis); and RCA territory 67-80% (qualitative analysis), 67-60% (semiquantitative analysis), 67-80% (quantitative analysis). CONCLUSION: These data suggest that 99mTc-sestamibi SPECT is a useful noninvasive tool in the follow-up evaluation of patients who have undergone angiographically successful coronary angioplasty even in the absence of a pre-PTCA perfusion study.

Angioplasty, Balloon, Coronary↗

PubMed2006

Mayday--a microarray data analysis workbench.

UNLABELLED: Mayday is a workbench for visualization, analysis and storage of microarray data. It features a graphical user interface and supports the development and integration of existing and new analysis methods. Besides the infrastructural core functionality, Mayday offers a variety of plug-ins, such as various interactive viewers, a connection to the R statistical environment, a connection to SQL-based databases and different data mining methods, including WEKA-library based methods for classification and various clustering methods. In addition, so-called meta information objects are provided for annotation of the microarray data allowing integration of data from different sources, which is a feature that, for instance, is employed in the enhanced heatmap visualization. SUPPLEMENTARY INFORMATION: The software and more detailed information including screenshots and a user guide as well as test data can be found on the Mayday home page http://www.zbit.uni-tuebingen.de/pas/mayday. The core is published under the GPL (GNU Public License) and the associated plug-ins under the LGPL (Lesser GNU Public License).

Computer Graphics↗

PubMed1999

Quantitative assessment of myositis in thigh muscles using magnetic resonance imaging.

Magnetic resonance (MR) imaging has been suggested as a technique for diagnosing and monitoring myositis, an inflammatory muscle disease. To date, the assessment of disease from MR images has been by subjective visual analysis. We describe here an objective, semi-automatic, computer-based method for quantifying the degree of disease from MR images, without the need for a radiologist or physician trained in the visual assessment of the MR images. The method is based on analysis of the histogram of intensity values produced from the MR images. The analysis yielded measures of the intensity and extent of disease. These two measures were combined to produce a calculated myositis index (CMI) which described the degree of disease evident from the MR images. This index was compared with a clinical assessment of the patient's condition, based on currently accepted, invasive and non-invasive, non-imaging criteria. Receiver operating characteristic (ROC) curve analysis showed that calculated myositis index agreed at least as well with clinical assessment as did visual analysis (receiver operating characteristic area = 0.93 and 0.94, p = not significant (NS), respectively, for separating remission from disease). Even using only two central MR slices for each patient, the receiver operating characteristic area for calculated myositis index was 0.92, implying that very short acquisition times are possible. We conclude that quantitative histogram analysis of MR images can be successfully performed with minimal operator input and using few MR slices. Agreement with more invasive clinical assessment is good and the method has the advantages of repeatability, objectivity, and decreased scan and analysis time.

Adult↗

PubMed2004

18F-FDG PET for detecting recurrent head and neck cancer, local lymph node involvement and distant metastases. Comparison of qualitative visual and semiquantitative analysis.

AIM: Assessment of the clinical value of (18)F-FDG-PET for detection of recurrent head and neck cancer, local lymph node involvement and distant metastases comparing a qualitative visual with a semiquantitative analysis (SUV values). PATIENTS, METHODS: Retrospective evaluation of 73 (18)F-FDG PET studies in 55 patients by use of a four-step qualitative visual grading system and calculation of standard uptake values in pathological lesions. Calculation of SUV values in normal regions for generating a map of physiological (18)F-FDG distribution. Correlation to histopathological findings and clinical follow-up. RESULTS: 1. Qualitative visual analysis of (18)F-FDG PET studies: a) local recurrence sensitivity 79%, specificity 97%, positive predictive value 95%, negative predictive value 85%, and diagnostic accuracy 89%; b) local metastatic lymph nodes 100%, 95%, 85%, 100%, 96%; c) distant metastases 100%, 98%, 86%, 100%, 98%, respectively. 2. Semiquantitative analysis had only little incremental, non-significant value in comparison to qualitative visual analysis for the detection of a local recurrence in two patients: a) local recurrence: sensitivity 83%, specificity 100%, positive predictive value 100%, negative predictive value 88%, and diagnostic accuracy 93%; b) local metastatic lymph nodes or c) distant metastases did not change in comparison to qualitative visual analysis. CONCLUSION: (18)F-FDG PET is an effective tool for re-staging of patients with suspected recurrence after therapy for head and neck cancer.

Carcinoma, Squamous Cell↗

PubMed1982

Interpreting results of single-subject research designs.

Although single-subject research design has been discussed at some length in the recent physical therapy and occupational therapy literature, there has been little attempt to describe the procedures used for interpreting the experimental effects of such research. The purpose of this paper is to present the use of two strategies for determining whether changes have occurred as a result of experimental manipulation. The first strategy, visual analysis of graphed data, relies on visual interpretation of changes in data patterns both within and between experimental conditions. The second strategy is the use of statistical procedures such as trend estimation, the Rn statistic, and time series analysis. Finally, the issues of both clinical and statistical significance in interpreting the results of single-subject research are discussed.

Methods↗

PubMed1996

Carboxymethyl-dextran-gadolinium-DTPA as a blood-pool contrast agent for magnetic resonance angiography. Experimental study in rabbits.

RATIONALE AND OBJECTIVES: The authors evaluate the efficiency of various doses of a paramagnetic macromolecular contrast agent, a gadolinium (Gd)-DTPA-dextran conjugate, as a blood-pool contrast media, in a transverse three-dimensional time-of-flight (TOF) magnetic resonance (MR) angiography sequence of the abdominal aorta in rabbits. METHODS: Imaging experiments were performed on a 1.5-T magnet, using a transverse three-dimensional TOF tilted optimized nonsaturating excitation (TONE) sequence. The macromolecular contrast media used was a carboxymethyl-dextran-Gd-DTPA (CMD-Gd-DTPA). Different concentrations of CMD-Gd-DTPA (0.005, 0.01, 0.03, 0.05 mmol Gd/kg) were evaluated. A comparative study using Gd-DOTA (0.01 and 0.1 mmol/kg) was performed. A visual analysis based on the gain in the visualized length of small arteries (renal arteries), and a quantitative analysis based on the percent contrast enhancement of the aorta plotted against distance in the slab from the top edge of the acquisition volume were obtained. RESULTS: A signal-to-noise ratio enhancement of the distal part of the aorta and an improvement in the visualized length of the renal arteries were noted for concentrations of CMD-Gd-DTPA ranging form 0.01 to 0.05 mmol Gd/kg. Venous enhancement was noted for concentrations greater than 0.01 mmol Gd/kg when using CMD-Gd-DTPA or Gd-DOTA. CONCLUSION: Carboxymethyl-dextran-Gd-DTPA reduced, in part, the saturation effect in a three-dimensional transverse TOF TONE MR angiography in rabbits. To prevent venous enhancement, observed with the higher concentrations used in this study, a decrease in the polydispersity of the polymer should be a goal in the future. Rapid extravasation of the low-molecular weight fraction of the polymer could explain the venous enhancement.

Animals↗

PubMed2005

Somatostatin receptor scintigraphy in metastatic breast cancer patients.

The purpose of this study was to evaluate the efficacy of somatostatin receptor scintigraphy (SRS) in imaging metastases in patients with advanced breast cancer (BC), and assess the relationship between exposure to chemotherapy and hormonotherapy with overexpression of somatostatin receptor (SS-R) on the breast cancer cell surface. Twelve patients with metastatic breast cancer were intravenously (i.v.) injected with In-111 pentatreotide (120 MBq). Early and later images were obtained with a double-head gamma camera equipped with medium-energy collimators. SPECT was performed when needed. Imaging results were compared with computed tomography and bone scan. Uptake levels were evaluated by site-specific visual analysis. Metastatic breast cancer can be visualized with SRS. Global sensitivity of imaging was 80% and specificity for correct prediction of tumor absence was 100%. Sensitivity was significantly higher for bone and lung metastases. SRS results related to the expression of SS-R on metastatic cell surfaces did not evidence a relationship with the biologic characteristics of the primary BC and drug exposure. In our series, SRS quantitative analysis demonstrated that tumor metastases differ greatly in uptake levels. Fifteen percent of metastatic sites in our series showed strong uptake. Our data support the important specificity of SRS in identifying BC metastases, mostly in cases of bone and lung disease, as well as the role of SRS in predicting responsiveness of metastatic BC cells to treatment with somatostatin analogues (SS), when SS-Rs are overexpressed on cell surfaces. If our results are confirmed in large scale studies, SRS shows the potential to treat selected patients with overexpressed SS-R on their tumoral cells with designed target therapies with SS analogue.

Adolescent↗

PubMed2005

Usefulness of myocardial parametric imaging to evaluate myocardial viability in experimental and in clinical studies.

OBJECTIVE: To evaluate whether myocardial parametric imaging (MPI) is superior to visual assessment for the evaluation of myocardial viability. METHODS AND RESULTS: Myocardial contrast echocardiography (MCE) was assessed in 11 pigs before, during, and after left anterior descending coronary artery occlusion and in 32 patients with ischaemic heart disease by using intravenous SonoVue administration. In experimental studies perfusion defect area assessment by MPI was compared with visually guided perfusion defect planimetry. Histological assessment of necrotic tissue was the standard reference. In clinical studies viability was assessed on a segmental level by (1) visual analysis of myocardial opacification; (2) quantitative estimation of myocardial blood flow in regions of interest; and (3) MPI. Functional recovery between three and six months after revascularisation was the standard reference. In experimental studies, compared with visually guided perfusion defect planimetry, planimetric assessment of infarct size by MPI correlated more significantly with histology (r2 = 0.92 versus r2 = 0.56) and had a lower intraobserver variability (4% v 15%, p < 0.05). In clinical studies, MPI had higher specificity (66% v 43%, p < 0.05) than visual MCE and good accuracy (81%) for viability detection. It was less time consuming (3.4 (1.6) v 9.2 (2.4) minutes per image, p < 0.05) than quantitative blood flow estimation by regions of interest and increased the agreement between observers interpreting myocardial perfusion (kappa = 0.87 v kappa = 0.75, p < 0.05). CONCLUSION: MPI is useful for the evaluation of myocardial viability both in animals and in patients. It is less time consuming than quantification analysis by regions of interest and less observer dependent than visual analysis. Thus, strategies incorporating this technique may be valuable for the evaluation of myocardial viability in clinical routine.

Aged↗

PubMed1985

Automatic identification of late potentials.

The purpose of the present study was to develop an algorithm for the automated identification of ventricular late potentials (LP) that can be recorded non-invasively by means of the signal averaging technique. This new algorithm was designed to determine the possible presence and the onset and duration of a given LP by analyzing the end of the QRS complex. As there is no objective standard for identifying these late potentials, the new algorithm was developed by continuous comparison and adaptation to visual analysis in 65 patients (algorithm definition phase). In the subsequent trial phase, visual and automated analysis were compared in a second cohort of 50 patients (40 patients with and 10 patients without late potentials). In the latter 50 patients, the results obtained with the new algorithm corresponded to the analysis made by at least two of three independent observers in 92% of cases. In only four patients--one without and three with late potentials--there was no agreement between the observers and the new program. In conclusion, the new algorithm can be used reliably for the evaluation of late potentials. The results are more objective. They are reproducible, which is of great advantage when data from different groups are to be compared or when less experienced investigators are using non-invasive methods for registration of late potentials.

Arrhythmias, Cardiac↗