Quality grading of Atlantic salmon (Salmo salar) by computer vision.

In this study, we present a promising method of computer vision-based quality grading of whole Atlantic salmon (Salmo salar). Using computer vision, it was possible to differentiate among different quality grades of Atlantic salmon based on the external geometrical information contained in the fish images. Initially, before the image acquisition, the fish were subjectively graded and labeled into grading classes by a qualified human inspector in the processing plant. Prior to classification, the salmon images were segmented into binary images, and then feature extraction was performed on the geometrical parameters of the fish from the grading classes. The classification algorithm was a threshold-based classifier, which was designed using linear discriminant analysis. The performance of the classifier was tested by using the leave-one-out cross-validation method, and the classification results showed a good agreement between the classification done by human inspectors and by the computer vision. The computer vision-based method classified correctly 90% of the salmon from the data set as compared with the classification by human inspector. Overall, it was shown that computer vision can be used as a powerful tool to grade Atlantic salmon into quality grades in a fast and nondestructive manner by a relatively simple classifier algorithm. The low cost of implementation of today's advanced computer vision solutions makes this method feasible for industrial purposes in fish plants as it can replace manual labor, on which grading tasks still rely.

Atlantic salmon skin and fillet color changes effected by perimortem handling stress, rigor mortis, and ice storage.

The changes in skin and fillet color of anesthetized and exhausted Atlantic salmon were determined immediately after killing, during rigor mortis, and after ice storage for 7 d. Skin color (CIE L*, a*, b*, and related values) was determined by a Minolta Chroma Meter. Roche SalmoFan Lineal and Roche Color Card values were determined by a computer vision method and a sensory panel. Before color assessment, the stress levels of the 2 fish groups were characterized in terms of white muscle parameters (pH, rigor mortis, and core temperature). The results showed that perimortem handling stress initially significantly affected several color parameters of skin and fillets. Significant transient fillet color changes also occurred in the prerigor phase and during the development of rigor mortis. Our results suggested that fillet color was affected by postmortem glycolysis (pH drop, particularly in anesthetized fillets), then by onset and development of rigor mortis. The color change patterns during storage were different for the 2 groups of fish. The computer vision method was considered suitable for automated (online) quality control and grading of salmonid fillets according to color.

Computer vision-based evaluation of pre- and postrigor changes in size and shape of Atlantic cod (Gadus morhua) and Atlantic salmon (Salmo salar) fillets during rigor mortis and ice storage: effects of perimortem handling stress.

The present study describes the possibilities for using computer vision-based methods for the detection and monitoring of transient 2D and 3D changes in the geometry of a given product. The rigor contractions of unstressed and stressed fillets of Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) were used as a model system. Gradual changes in fillet shape and size (area, length, width, and roundness) were recorded for 7 and 3 d, respectively. Also, changes in fillet area and height (cross-section profiles) were tracked using a laser beam and a 3D digital camera. Another goal was to compare rigor developments of the 2 species of farmed fish, and whether perimortem stress affected the appearance of the fillets. Some significant changes in fillet size and shape were found (length, width, area, roundness, height) between unstressed and stressed fish during the course of rigor mortis as well as after ice storage (postrigor). However, the observed irreversible stress-related changes were small and would hardly mean anything for postrigor fish processors or consumers. The cod were less stressed (as defined by muscle biochemistry) than the salmon after the 2 species had been subjected to similar stress bouts. Consequently, the difference between the rigor courses of unstressed and stressed fish was more extreme in the case of salmon. However, the maximal whole fish rigor strength was judged to be about the same for both species. Moreover, the reductions in fillet area and length, as well as the increases in width, were basically of similar magnitude for both species. In fact, the increases in fillet roundness and cross-section height were larger for the cod. We conclude that the computer vision method can be used effectively for automated monitoring of changes in 2D and 3D shape and size of fish fillets during rigor mortis and ice storage. In addition, it can be used for grading of fillets according to uniformity in size and shape, as well as measurement of fillet yield measured in thickness. The methods are accurate, rapid, nondestructive, and contact-free and can therefore be regarded as suitable for industrial purposes.

Computer vision-based sorting of Atlantic salmon (Salmo salar) fillets according to their color level.

Computer vision method was used to evaluate the color of Atlantic salmon (Salmo salar) fillets. Computer vision-based sorting of fillets according to their color was studied on 2 separate groups of salmon fillets. The images of fillets were captured using a digital camera of high resolution. Images of salmon fillets were then segmented in the regions of interest and analyzed in red, green, and blue (RGB) and CIE Lightness, redness, and yellowness (Lab) color spaces, and classified according to the Roche color card industrial standard. Comparisons of fillet color between visual evaluations were made by a panel of human inspectors, according to the Roche SalmoFan lineal standard, and the color scores generated from computer vision algorithm showed that there were no significant differences between the methods. Overall, computer vision can be used as a powerful tool to sort fillets by color in a fast and nondestructive manner. The low cost of implementing computer vision solutions creates the potential to replace manual labor in fish processing plants with automation.

Optimization of ECG gating in quantitative femoral angiography.

PURPOSE: To determine which phase of the heart cycle would yield the highest reproducibility in measuring atherosclerosis-related variables such as arterial lumen volume and edge roughness. MATERIAL AND METHODS: 35 patients with hypercholesterolemia underwent select- ive femoral angiography, repeated four times at 10-min intervals. The angiographies were performed with ECG-gated exposures. In angiographies 1 and 2 the delay from R-wave maximum to each exposure was 0.1 s, in angiographies 3 and 4 the delay was 0.1, 0.3, 0.5 or 0.7 s or the exposures were performed 1/s without ECG gating. Arterial lumen volume and edge roughness were measured in a 20-cm segment of the superficial femoral artery using a computer-based densitometric method. Measurement reproducibility was determined by comparing angiographies 1-2 and angiographies 3-4. RESULTS: When measuring arterial lumen volume and edge roughness of a 20-cm segment of the femoral artery, reproducibility was not dependent on ECG gating. In measuring single arterial diameters and cross-sectional areas, the reproducibility was better when exposures were made 0.1 s after the R-wave maximum than when using other settings of the ECG gating device or without ECG gating. CONCLUSION: The influence of pulsatile flow upon quantitative measurement in femoral angiograms seems to be the smallest possible in early systole, as can be demonstrated when measuring single diameters and cross-sectional areas. In variables based on integration over longer segments, measurement reproducibility seems to be independent of phase.

Allergic reactions at repeat femoral angiography with ioxaglate.

PURPOSE: To study the occurrence of allergy-like reactions at angiography, repeated several times, and, secondly, to evaluate the effect of prophylactic treatment in individuals who had earlier experienced such reactions. MATERIAL AND METHODS: One hundred and fifty-seven patients with hypercholesterolaemia, participating in the Probucol Quantitative Regression Swedish Trial (PQRST), underwent aortofemoral angiography with ioxaglate (Hexabrix) repeated annually for 3 years. Allergic reactions to the contrast medium were recorded. At the following angiographies, all patients who had earlier experienced such reactions were treated prophylactically with steroids and antihistamine. RESULTS: Allergic reactions were observed in 35 patients. Twelve reacted only year 0, 3 only year 1, 5 only year 2 and 6 only year 3. Eight patients had at least one reaction also when treated prophylactically. It was significantly (p<0.05) more common to react at year 0 but not at year 1 than to react at year 1 but not at year 0. At years 1, 2 and 3 the frequency of reactions was significantly greater in the group given prophylactic treatment than in the group without any earlier reaction at all: 8/20 versus 3/137, 4/23 versus 6/134, and 6/29 versus 6/128, respectively. CONCLUSION: Some individuals had an increased risk of an allergy-like reaction to the contrast agent. Prophylactic treatment reduced the risk of renewed reactions, but not to the same level as for those without earlier reaction. Nevertheless, individuals who have had earlier reactions can be investigated in the future, with prophylactic treatment.

Effect of furosemide or mannitol before injection of a non-ionic contrast medium on intrarenal oxygen tension.

Oxygen tension (pO2) in rat renal cortex and outer medulla was studied after an intravenous injection of mannitol or furosemide, followed 10 minutes later by an intravenous injection of the non-ionic X-ray contrast medium (CM) iopromide (370 mg iodine/ml). Ten minutes after mannitol injection, before injection of CM, pO2 in the medulla had decreased from a control level of 32 +/- 3 to 28 +/- 4 mm Hg. The addition of CM caused a further decrease, to 24 +/- 5 mm Hg, which was a significant reduction. Ten minutes after furosemide injection the pO2 in the medulla had increased significantly, from a control value of 32 +/- 2 to 44 +/- 4 mm Hg. Injection of CM caused a significant decrease in pO2 to 37 +/- 3 mm. Ringer's solution (n = 6) caused no changes. We conclude that pretreatment with mannitol or furosemide does not prevent the CM-induced decrease in pO2 in the outer medulla.

Injection of low and iso-osmolar contrast medium decreases oxygen tension in the renal medulla.

The oxygen tension (PO2) in the renal cortex and outer renal medulla in 26 rats was studied by use of oxygen microelectrodes before and after injection of x-ray contrast media (CM). The CM, iopromide, ioxaglate and iotrolan were administrated intravenously in iodine equivalent doses (1,600 mg iodine/kg body wt). Ringer's solution was used as the control. In the outer medulla, all three CM induced a decrease in PO2: iopromide (N = 6) from 30 +/- 3 to 18 +/- 4 mm Hg; ioxaglate (N = 7) from 32 +/- 6 to 15 +/- 4 mm Hg; and iotrolan (N = 6) from 36 +/- 3 to 14 +/- 4 mm Hg. All these decreases were significant. After the injection of Ringer's (N = 7) there was an increase from 34 +/- 3 to 35 +/- 3 mm Hg. In the cortex a slight decrease was noted for injection of CM, but this was significant only after injection of iotrolan. All tested contrast media decrease PO2 in the outer renal medulla, which may partly explain contrast medium-induced acute renal failure.

Effects of contrast media and mannitol on renal medullary blood flow and red cell aggregation in the rat kidney.

Hemodynamic factors may play a role in the development of acute renal failure following administration of contrast media (CM). In this study the effect of intravenous injection of contrast media and mannitol on red blood cell velocity (VRBC) and red blood cell aggregation in renal medullary vessels was studied in 58 rats. Renal medullary blood flow was investigated by a cross-correlation technique and by a visual aggregation score. The CM, namely diatrizoate, iopromide, iohexol, ioxaglate, iotrolan, were given in iodine equivalent doses (1600 mg/kg body wt). Mannitol (950 mOsm/liter) and Ringer's solution were used as controls. The same vessels were studied 30 minutes before and 30 minutes after injections. VRBC decreased significantly after injection of diatrizoate, iopromide, iohexol, iotrolan and mannitol. Ringer's solution and ioxaglate did not significantly alter medullary blood flow, while iotrolan and mannitol caused the largest decreases in VRBC. All CM and mannitol caused both red cell aggregation and cessation of blood flow. The decrease in blood flow and increase in red blood cell aggregation after injection of CM and mannitol may partly explain the occurrence of contrast medium-induced acute renal failure.

Lowering of HDL2b by probucol partly explains the failure of the drug to affect femoral atherosclerosis in subjects with hypercholesterolemia. A Probucol Quantitative Regression Swedish Trial (PQRST) Report.

The aim of the Probucol Quantitative Regression Swedish Trial (PQRST) (n = 303) was to investigate whether probucol (0.5 g BID) added to diet and cholestyramine (8 g BID) could retard progression or induce regression of femoral atherosclerosis in hypercholesterolemic (> 6.86 mmol/L) subjects. Probucol did not induce regression over the 3-year trial period as estimated by change in lumen volume on quantitative arteriography of a 20-cm segment of the femoral artery. In this report we studied in a representative subgroup (n = 72) whether the reduction in HDL concentrations induced by probucol could explain the failure of the drug to be effective. We analyzed the effects of treatment on HDL particle size subclasses. Probucol lowered the relative level of HDL2b, comprising the largest HDL particles, by 53% and the protein concentration of HDL2b by 67%. The protein reduction in HDL was mainly confined to the apolipoprotein A-I moiety. The change in lumen volume correlated significantly with change in HDL, ie, HDL cholesterol (r = .34, P < .01), HDL2 cholesterol (r = .37, P < .01), HDL2b protein (r = .44, P < .001), and the relative HDL2b value (r = .51, P < .001). The corresponding values for relative HDL2b, distribution calculated on the active (n = 35) and placebo (n = 37) groups separately were also significant (r = .39 and .32, respectively; both P < .05). The correlation between drug-induced change in the relative HDL2b concentration and change in atherosclerosis was independent of the alteration in triglyceride concentration and could not be explained by treatment interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Predilection of atherosclerosis for the inner curvature in the femoral artery. A digitized angiography study.

The degree of atherosclerosis in the inner and outer curvature of the femoral artery was studied by using digitized angiography and edge-roughness calculations in 301 hyperlipidemic patients. When the two edges of the vessel were compared no significant difference was seen, but when the local curvature was taken into account, inner curves were found to be more atherosclerotic than outer curves, and both inner and outer curves were more affected than straight segments. The same pattern was encountered in subpopulations defined by clinical or blood lipid criteria. The suggested explanation is that flow disturbances such as low shear rates or separated flow, which tend to arise along the inner curvature, promote the development of atherosclerosis.

The effect of probucol on femoral atherosclerosis: the Probucol Quantitative Regression Swedish Trial (PQRST).

The Probucol Quantitative Regression Swedish Trial tested whether treatment of hypercholesterolemic persons with probucol for 3 years affected femoral atherosclerosis. The primary end point was the change in atheroma volume estimated as change in lumen volume of the femoral artery assessed by quantitative arteriography. Three hundred three patients with visible atherosclerosis were randomized to probucol 0.5 g, twice daily, or to placebo. All patients were given diet and cholestyramine, 8 to 16 g/day. Twenty-nine patients were excluded because of inadequate primary end point measurements. The mean age of the remaining 274 subjects (158 were men) was 55 years. Seventeen percent had intermittent claudication and 24% had angina pectoris. After 3 years, the probucol-treated patients had 17% lower serum cholesterol, 12% lower low-density lipoprotein cholesterol, 24% lower total high-density lipoprotein cholesterol, and 34% lower high-density lipoprotein2 cholesterol levels than control subjects. All lipoprotein differences between the treatment groups remained highly significant during the trial. There was no statistically significant change in lumen volume between the probucol and the control group. Furthermore, there was no difference between the treatment groups with regard to change in arterial edge roughness or amount of aorto-femoral atherosclerosis; neither were there any differences between the treatment groups with regard to change in ST-segment depressions on exercise tests or ankle/arm blood pressure (secondary end points). In the control group, lumen volume increased (p < 0.001) and roughness of the femoral artery decreased (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The relation of coronary and peripheral arterial disease to the severity of femoral atherosclerosis in hypercholesterolaemia.

OBJECTIVES: The extent of atherosclerosis in the superficial femoral artery and the severity of arterial disease in the aorto-iliac and femoro-popliteal arterial districts were related to clinical diagnosis of coronary and peripheral atherosclerosis in hypercholesterolaemic patients. DESIGN: The study constitutes baseline cross-sectional data of a randomized double-blind clinical trial on Probucol, using both computer based and visual estimations of angiographies as endpoints. SUBJECTS: Two hundred and ninety men and women (mean age 54 years) with hypercholesterolaemia. MAIN OUTCOME MEASURES: Atherosclerosis was estimated with arteriographies. Lumen volume and edge roughness (vessel inner wall irregularity) of a 20 cm segment of the femoral artery were estimated by computer. A visual atherosclerosis score of the abdominal aorta to the popliteal arteries was made on both sides. RESULTS: Patients with peripheral arterial disease had significantly more advanced disease according to all three angiographic variables than those without symptoms of peripheral vascular disease. Both men and women with coronary artery disease had significantly lower femoral lumen volume and higher roughness values than patients without. Men with previous myocardial infarction had significantly higher mean visual scores of atherosclerosis than those without, while lumen volume and roughness did not differ in either sex. CONCLUSIONS: Femoral atherosclerosis is an expression of a generalized disease, associated with clinical symptoms of coronary artery disease. Femoral atherosclerosis is often accompanied by atherosclerosis also in the coronary arteries.

Distribution of coronary atherosclerosis and its correlation to metabolic risk factors and femoral atherosclerosis.

Coronary angiography was performed in 216 men of whom 78 also had a cine-angiogram of one femoral artery. Stenoses of the coronary arteries were measured with a pair of calipers and the femoral angiograms were computer-analysed. The patients were divided into 2 groups according to whether the bulk of the coronary stenoses affected the central or the peripheral part of the coronary arteries. The groups were investigated regarding differences in lipid and metabolic risk factors. Coronary atherosclerosis was most often found in the proximal part of the right coronary arteries. No significant correlation between coronary and femoral atherosclerosis was found. Previous myocardial infarction was associated with more coronary artery stenosis (p < 0.003). No pattern of risk factors was found to discriminate between central and peripheral coronary atherosclerosis.

Reproducibility of quantitative arteriographic assessment of atherosclerosis in the femoral artery.

Results from computer-analysed angiograms in the Probucol Quantitative Regression Swedish Trial (PQRST) were analysed to determine the reproducibility of the method and any drift in the analysing system. The precision index (P(mu)) for 2 angiography series, made at 10 min intervals, of the femoral artery in 276 patients was 10.5 for lumen volume and 21.9 for roughness (edge irregularity). No difference in reproducibility was found between patients with and without symptoms of peripheral atherosclerosis or when looking at the reproducibility over years. A drift of 0.67% per year in the radiographic equipment (but not in the analysis system) was found, confirmed by use of phantoms. Computer-based analysis of femoral atherosclerosis is a reliable method for follow-up trials, giving high reproducibility even if the trial spans over several years and involves different centres. The use of phantoms is essential for checking the method over time.

Flow disturbances in early femoral atherosclerosis--an in vivo study with digitized cineangiography.

Disturbances in arterial flow are believed to influence the localization and development of atherosclerotic plaques. The femoral arteries of 26 patients were studied with cineangiography, after which the films were digitized and analyzed with an image analysis computer. The image sequence was converted to a set of time-intensity curves, from which time parameters were calculated, representing the arrival time of the contrast medium at each pixel. In the resulting parametric images, zones of delayed contrast filling (ZDF) were identified by an adaptive thresholding, which identifies lighter regions within the vessel, excluding the smallest ones. The ZDF, which have been shown, in a model study, to correspond to disturbed flow, were more frequent in the inner curvature than in the outer curvature of the curved vessels. Accordingly, they were more frequent along the lateral wall than along the medial wall of the artery. Several ZDF were also found in the vicinity of bifurcations. Most of the findings tally closely with fluid mechanical theory. In future studies, flow disturbances are to be correlated with the progression of atherosclerotic lesions.

Two-dimensional tortuosity of the superficial femoral artery in early atherosclerosis.

Tortuosity of an artery can disturb fluid mechanics and cause flow separation, which might in turn promote atherogenesis. This study discusses theoretically several quantitative measures of arterial tortuosity and curvature in two dimensions and tests them with computations from digitized femoral arteriograms. When reproducibility, sensitivity to scaling and computational procedure, and agreement between the measures were all taken into account, the total curvature and distance factor were considered the most suitable measures. Significant correlations were found between tortuosity and atherosclerosis measures, but the interpretation of this finding is not straightforward.

Influence of contrast media on single nephron glomerular filtration rate in rat kidney. A comparison between diatrizoate, iohexol, ioxaglate, and iotrolan.

The effects of slow (10 min) i.v. infusions of contrast media (CM, 1,600 mg I/kg b.w.) on single nephron glomerular filtration rate (SNGFR) in the rat kidney were investigated using a micropuncture technique. Diatrizoate, iohexol, or ioxaglate did not change SNGFR, although a tendency towards a transient suppression was seen during the infusion phase. Iotrolan infusion, however, decreased SNGFR (p < 0.05) and the value still remained below the control value 25 min after the start of infusion. Iotrolan is a nonionic dimeric CM and has a lower osmotic effect in the tubules than the ionic dimeric CM and the monomeric CM when given in iodine equivalent doses. These characteristics of iotrolan have probably some influence on the depression of SNGFR after iotrolan injection.

Complications of percutaneous pericardiocentesis under fluoroscopic guidance.

Complications in 352 cases of fluoroscopy-guided percutaneous pericardiocentesis accomplished through an indwelling catheter were reviewed following surgery and non-surgery. Thirteen major complications were found, namely 3 cardiac perforations, 2 cardiac arrhythmias, 4 cases of arterial bleeding, 2 cases of pneumothorax in children, one infection, and one major vagal reaction. No significant difference in complications was found between pericardiocenteses for pericardial effusions after cardiac surgery (n = 208) and those for effusions of non-surgical (n = 144) origin. Fluoroscopy-guided pericardiocentesis by the subxiphoid approach with placement of an indwelling catheter is a safe method for achieving pericardial drainage in both surgical and non-surgical effusions. Accidental cardiac perforation with a fine needle is a minor complication as long as the needle is directed towards the anterior diaphragmatic border of the right ventricle and drainage is achieved with a reliable indwelling catheter.