Sources of performance variability in deep learning-based polyp detection.

PURPOSE: Validation metrics are a key prerequisite for the reliable tracking of scientific progress and for deciding on the potential clinical translation of methods. While recent initiatives aim to develop comprehensive theoretical frameworks for understanding metric-related pitfalls in image analysis problems, there is a lack of experimental evidence on the concrete effects of common and rare pitfalls on specific applications. We address this gap in the literature in the context of colon cancer screening. METHODS: Our contribution is twofold. Firstly, we present the winning solution of the Endoscopy Computer Vision Challenge on colon cancer detection, conducted in conjunction with the IEEE International Symposium on Biomedical Imaging 2022. Secondly, we demonstrate the sensitivity of commonly used metrics to a range of hyperparameters as well as the consequences of poor metric choices. RESULTS: Based on comprehensive validation studies performed with patient data from six clinical centers, we found all commonly applied object detection metrics to be subject to high inter-center variability. Furthermore, our results clearly demonstrate that the adaptation of standard hyperparameters used in the computer vision community does not generally lead to the clinically most plausible results. Finally, we present localization criteria that correspond well to clinical relevance. CONCLUSION: We conclude from our study that (1) performance results in polyp detection are highly sensitive to various design choices, (2) common metric configurations do not reflect the clinical need and rely on suboptimal hyperparameters and (3) comparison of performance across datasets can be largely misleading. Our work could be a first step towards reconsidering common validation strategies in deep learning-based colonoscopy and beyond.

Revision surgery for cervical artificial disc: Surgical technique and clinical results.

OBJECTIVE: Cervical artificial disc replacement (C-ADR) was developed with the goal of preserving mobility of the cervical segment in patients with degenerative disc disease. So far, little is known about experiences with revision surgery and explantation of C-ADRs. Here, we report our experience with revision the third generation, Galileo-type disc prosthesis from a retrospective study of two institutions. PATIENTS AND METHODS: Between November 2008 and July 2016, 16 patients with prior implantation of C-ADR underwent removal of the Galileo-type disc prosthesis (Signus, Medizintechnik, Germany) due to a call back by industry. In 10 patients C-ADR was replaced with an alternative prosthesis, 6 patients received an ACDF. Duration of surgery, time to revision, surgical procedure, complication rate, neurological status, histological findings and outcome were examined in two institutions. RESULTS: The C-ADR was successfully revised in all patients. Surgery was performed through the same anterior approach as the initial access. Duration of the procedure varied between 43 and 80min. Access-related complications included irritation of the recurrent nerve in one patient and mal-positioning of the C-ADR in another patient. Follow up revealed two patients with permanent mild/moderate neurologic deficits, NDI (neck disability index) ranged between 10 and 42%. CONCLUSIONS: Anterior exposure of the cervical spine for explantation and revision of C-ADR performed through the initial approach has an overall complication rate of 18.75%. Replacements of the Galileo-type disc prosthesis with an alternative prosthesis or conversion to ACDF are both suitable surgical options without significant difference in outcome.

Behavioral deficits in sepsis-surviving rats induced by cecal ligation and perforation.

Sepsis and its complications are the leading causes of mortality in intensive care units, accounting for 10-50% of deaths. Intensive care unit survivors present long-term cognitive impairment, including alterations in memory, attention, concentration, and/or global loss of cognitive function. In the present study, we investigated behavioral alterations in sepsis-surviving rats. One hundred and ten male Wistar rats (3-4 months, 250-300 g) were submitted to cecal ligation and puncture (CLP), and 44 were submitted to sham operation. Forty-four rats (40%) survived after CLP, and all sham-operated animals survived and were used as control. Twenty animals of each group were used in the object recognition task (10 in short-term memory and 10 in long-term memory), 12 in the plus-maze test and 12 in the forced swimming test. Ten days after surgery, the animals were submitted individually to an object recognition task, plus-maze and forced swimming tests. A significant impairment of short- and long-term recognition memory was observed in the sepsis group (recognition index 0.75 vs 0.55 and 0.74 vs 0.51 for short- and long-term memory, respectively (P < 0.05). In the elevated plus-maze test no difference was observed between groups in any of the parameters assessed. In addition, sepsis survivors presented an increase in immobility time in the forced swimming test (180 vs 233 s, P < 0.05), suggesting the presence of depressive-like symptoms in these animals after recovery from sepsis. The present results demonstrated that rats surviving exposure to CLP, a classical sepsis model, presented recognition memory impairment and depressive-like symptoms but not anxiety-like behavior.

Behavioral deficits in sepsis-surviving rats induced by cecal ligation and perforation

Sepsis and its complications are the leading causes of mortality in intensive care units, accounting for 10-50 percent of deaths. Intensive care unit survivors present long-term cognitive impairment, including alterations in memory, attention, concentration, and/or global loss of cognitive function. In the present study, we investigated behavioral alterations in sepsis-surviving rats. One hundred and ten male Wistar rats (3-4 months, 250-300 g) were submitted to cecal ligation and puncture (CLP), and 44 were submitted to sham operation. Forty-four rats (40 percent) survived after CLP, and all sham-operated animals survived and were used as control. Twenty animals of each group were used in the object recognition task (10 in short-term memory and 10 in long-term memory), 12 in the plus-maze test and 12 in the forced swimming test. Ten days after surgery, the animals were submitted individually to an object recognition task, plus-maze and forced swimming tests. A significant impairment of short- and long-term recognition memory was observed in the sepsis group (recognition index 0.75 vs 0.55 and 0.74 vs 0.51 for short- and long-term memory, respectively (P < 0.05). In the elevated plus-maze test no difference was observed between groups in any of the parameters assessed. In addition, sepsis survivors presented an increase in immobility time in the forced swimming test (180 vs 233 s, P < 0.05), suggesting the presence of depressive-like symptoms in these animals after recovery from sepsis. The present results demonstrated that rats surviving exposure to CLP, a classical sepsis model, presented recognition memory impairment and depressive-like symptoms but not anxiety-like behavior.

Differential role of entorhinal and hippocampal nerve growth factor in short- and long-term memory modulation.

We studied the effects of infusion of nerve growth factor (NGF) into the hippocampus and entorhinal cortex of male Wistar rats (250-300 g, N = 11-13 per group) on inhibitory avoidance retention. In order to evaluate the modulation of entorhinal and hippocampal NGF in short- and long-term memory, animals were implanted with cannulae in the CA1 area of the dorsal hippocampus or entorhinal cortex and trained in one-trial step-down inhibitory avoidance (foot shock, 0.4 mA). Retention tests were carried out 1.5 h or 24 h after training to measure short- and long-term memory, respectively. Immediately after training, rats received 5 microl NGF (0.05, 0.5 or 5.0 ng) or saline per side into the CA1 area and entorhinal cortex. The correct position of the cannulae was confirmed by histological analysis. The highest dose of NGF (5.0 ng) into the hippocampus blocked short-term memory (P < 0.05), whereas the doses of 0.5 (P < 0.05) and 5.0 ng (P < 0.01) NGF enhanced long-term memory. NGF administration into the entorhinal cortex improved long-term memory at the dose of 5.0 ng (P < 0.05) and did not alter short-term memory. Taken as a whole, our results suggest a differential modulation by entorhinal and hippocampal NGF of short- and long-term memory.

Differential role of entorhinal and hippocampal nerve growth factor in short- and long-term memory modulation

We studied the effects of infusion of nerve growth factor (NGF) into the hippocampus and entorhinal cortex of male Wistar rats (250-300 g, N = 11-13 per group) on inhibitory avoidance retention. In order to evaluate the modulation of entorhinal and hippocampal NGF in short- and long-term memory, animals were implanted with cannulae in the CA1 area of the dorsal hippocampus or entorhinal cortex and trained in one-trial step-down inhibitory avoidance (foot shock, 0.4 mA). Retention tests were carried out 1.5 h or 24 h after training to measure short- and long-term memory, respectively. Immediately after training, rats received 5 æl NGF (0.05, 0.5 or 5.0 ng) or saline per side into the CA1 area and entorhinal cortex. The correct position of the cannulae was confirmed by histological analysis. The highest dose of NGF (5.0 ng) into the hippocampus blocked short-term memory (P < 0.05), whereas the doses of 0.5 (P < 0.05) and 5.0 ng (P < 0.01) NGF enhanced long-term memory. NGF administration into the entorhinal cortex improved long-term memory at the dose of 5.0 ng (P < 0.05) and did not alter short-term memory. Taken as a whole, our results suggest a differential modulation by entorhinal and hippocampal NGF of short- and long-term memory.

Structure-related oxidative damage in rat brain after acute and chronic electroshock.

The role of oxidative stress in electroconvulsive therapy-related effects is not well studied. The purpose of this study was to determine oxidative stress parameters in several brain structures after a single electroconvulsive seizure or multiple electroconvulsive seizures. Rats were given either a single electroconvulsive shock or a series of eight electroconvulsive shocks. Brain regions were isolated, and levels of oxidative stress in the brain tissue (cortex, hippocampus, striatum and cerebellum) were measured. We demonstrated a decrease in lipid peroxidation and protein carbonyls in the hippocampus, cerebellum, and striatum several times after a single electroconvulsive shock or multiple electroconvulsive shocks. In contrast, lipid peroxidation increases both after a single electroconvulsive shock or multiple electroconvulsive shocks in cortex. In conclusion, we demonstrate an increase in oxidative damage in cortex, in contrast to a reduction of oxidative damage in hippocampus, striatum, and cerebellum.

Second opinion: a computer expert system designed to aid in the determination of spectacle lens prescriptions.

BACKGROUND: Expert systems (ESs) are computer programs that simulate the decision-making ability of human experts. In this project, an ES was developed that used optometric data and decision rules to determine spectacle lens prescription powers. METHODS: Decision rules derived from clinical experience and standard references were provided to a commercially available shell program to create an ES called Second Opinion. The ES determined spherical, cylindrical, and add powers designed to provide maximum acuity consistent with a high probability of patient acceptance. CONCLUSIONS: Second Opinion demonstrates how a computer program can be used to analyze optometric data and offer suggestions regarding lens prescriptions.

The dizzy patient: a review of etiology, differential diagnosis, and management.

BACKGROUND: Dizziness is a lay term used to describe a variety of sensations. Unfortunately, the term "dizziness" does not have a precise medical definition, and additional information is typically required to further define the patient's problem. METHODS: When dizziness is a presenting complaint, distinctions must be made between vertigo (a sense of false movement), near-syncope (a feeling of impending faint), disequilibrium (loss of balance), and ill-defined lightheadedness (an inability to concentrate or focus the mind). Possible causes of dizziness include conflicts between visual and vestibular information, vascular problems, adverse reactions to medication, psychological difficulties, systemic disease, and the effects of aging. RESULTS: Dizziness is a symptom of a physiological or psychological illness, and therefore management is typically directed toward treatment of the underlying illness. In some cases the cause of the dizziness cannot be found, however, or is untreatable. In these cases, management is directed toward symptom reduction. CONCLUSIONS: Dizziness is a relatively common problem that arises from a variety of causes. In many cases, optometrists can participate in the diagnosis and management of patients with complaints of dizziness.

[An increased risk of kinesitherapy in silent myocardial ischemia?]. / Erhöhtes Risiko der Bewegungstherapie bei stummer Myokardischämie?

The effect of three-week standardized physical training on exercise-induced ischaemia was investigated in patients with silent ischaemia after myocardial infarction. 24-hour monitoring and exercise ECGs before and after the period of physical training, were undertaken in 32 men (mean age 53.6 +/- 8.1 years) with angiographically proven coronary heart disease. The protocol of the standardized exercise included bicycle ergometry, gymnastics, breathing and movement exercises, as well as nonstandardized walking or hiking. Following the training period the number of ischaemic episodes fell from 90 to 72 for the group as a whole and that of the asymptomatic episodes from 79 to 64. The number and severity of ventricular arrhythmias were similar during silent and symptomatic ischaemia. There was a significant increase in duration of exercise until reaching the ischaemia threshold (mean exercise duration 4.7 +/- 2.1 vs 5.9 +/- 2.5 min; P = 0.0007). There was no increased risk concerning ventricular arrhythmias.

Exploring the optometric application of expert computer systems: refractive error correction.

Using the commercially available shell programs NeuroShell and EXSYS, example-based and rule-based expert computer systems were developed to explore how such systems could be applied in an optometric environment. To demonstrate such an application, the example-based NeuroShell system was taught to prescribe sphere and cylinder powers for low refractive error myopes. When the system learned with only the chief complaint, habitual prescription and acuity through the habitual, and best refraction with resulting acuity, it predicted the sphere and cylinder powers prescribed by human optometrists within 0.25 diopter 97 and 98 percent of the time, respectively, for 60 test eyes. With a set of only three rules, the rule-based EXSYS system predicted sphere powers within 0.25 diopter of the prescribed powers for 100 percent of the 60 test eyes. Results with these very simple refractive problems suggest that teaching expert computer systems to prescribe ophthalmic lens corrections is possible, and further suggest that the concept could be extended to more complex and challenging patient populations.

Clinical comparison of air-puff and Goldmann tonometers.

Intraocular pressures (IOPs) as measured with the Topcon CT-10, Reichert XPERT and NCT II, and Keeler PULSAIR air-puff tonometers were compared to the Goldmann IOPs for 452 eyes ranging in pressure from 6-40 mmHg. For eyes with pressures in the 10-20 mmHg range, the CT-10 read consistently too high. The XPERT and the NCT II read too high in the lower part of this range and too low in the higher part. The PULSAIR read too low across the entire range. At higher pressures, all of the tonometers read too high except the PULSAIR which again read too low. CT-10, XPERT, and NCT II and PULSAIR pressures were within 4.0 mmHg of Goldmann readings for 81, 85, 89 and 72 percent of the eyes, respectively. Subjects selected the XPERT as the most preferred tonometer and the NCT II was the least preferred mainly because of perceived air-puff intensity.

Applications of expert computer systems.

An expert system is a computer program which uses artificial intelligence to make logical decisions on the basis of input data. The rules the system uses to make its decisions are called heuristics which can be provided in the form of IF . . . THEN statements, or they can be learned by the system from examples. The term "expert" is used because the rules or examples come from human experts and the program is considered to have captured their expertise. Currently there are many expert systems in business and medical use but few, if any, are used in optometry. The rule-oriented nature of many ophthalmic procedures suggests a future role for these systems, but their cost-effectiveness may not yet be favorable enough to justify development of expert systems for optometric practice.

Therapeutic pharmaceutical utilization by military optometrists.

The Air Force, Army, and Navy have instituted regulations that authorize optometrists to use therapeutic pharmaceutical agents (TPAs). A survey of clinical optometrists on active duty was conducted to evaluate the impact of these regulations on military optometry. The results indicate that the majority of optometrists support the regulations and are utilizing TPAs to treat a wide variety of ocular disorders. However, the survey also found a number of optometrists in each service who were dissatisfied with certain aspects of the regulations. Some Air Force and Navy optometrists expressed concern that their regulations did not allow access to TPAs which they felt qualified to use. Some Army respondents felt that their regulation was unduly influenced by local policy and was not an equitable means of granting therapeutic privileges. These concerns suggest that a reevaluation of the therapeutic regulations might be required in the future.

A comparison of diagnostic outcomes with and without pupillary dilatation.

To compare the quality of fundus evaluations conducted with natural and dilated pupils, 500 typical adult subjects, divided into five age categories, were examined using both techniques. Direct and monocular indirect ophthalmoscopes were used with the natural pupils; direct and binocular indirect scopes were used for the dilated examinations. Retinal anomalies were classified on the basis of posterior pole or peripheral location and whether the anomalies would require significant action by the doctor. Of the 32 posterior pole anomalies which required action, 38% were missed during the natural pupil examination; 51% of the anomalies not requiring immediate action were also missed. These miss rates, along with the 287 anomalies found in the periphery (20 of which required immediate action), suggest that dilation should be strongly considered for all patients so as to optimize the probability of detecting fundus anomalies.

Mitomycin C and mitoxantrone chemotherapy for advanced breast cancer: efficacy with minimal gastrointestinal toxicity and alopecia.

In an attempt to examine the possibility of decreased toxicity in patients with advanced breast cancer who had not previously received chemotherapy, 33 women were given combination chemotherapy consisting of mitomycin C (10 mg/m2) every 6 weeks and mitoxantrone (6 mg/m2) every 3 weeks. The patients had predominantly visceral disease and received a median of two cycles of therapy. Of the 32 evaluable subjects, 15 (47%) achieved a partial response lasting a median of 7 months. Hematological toxicity was generally mild, although there were two episodes of sepsis. One patient developed hemolytic-uremic syndrome, and one subject developed pulmonary fibrosis, both presumably attributable to treatment with mitomycin C. Another patient died of hepatic failure (hepar lobatum). Thus, there were five patients who sustained life-threatening toxicities; this may have been due to the poor performance status and advanced age of some of the patients. Gastrointestinal toxicity and alopecia were minimal. Patient acceptance was high and there was an improvement in symptomatology in the majority of patients. In conclusion, mitomycin C and mitoxantrone chemotherapy is an active drug combination for the treatment of advanced breast cancer that seldom causes significant distressing gastrointestinal side effects or alopecia; however, the duration of response to this regimen appears to be shorter than that obtained with either cyclophosphamide - methotrexate - 5-fluorouracil (CMF) or cyclophosphamide - Adriamycin - 5-fluorouracil (CAF) combination chemotherapy.

Effect of head and eye positions on fixation disparities, phorias, and ductions at near.

This study evaluated the effects of head and gaze position on near fixation disparity, phoria, and duction findings. A population of 104 non-complaining subjects divided by age into 3 groups participated in the study. The primary head and gaze position along with two others approximating the positions used for reading by nonbifocal and bifocal wearers were used. A statistically significant effect was found for the phoria data from the young group, but the magnitude was clinically insignificant. Changes in head and/or gaze positions did not significantly affect fixation disparities or duction recovery ranges. Phorias and fixation disparities showed statistically significant increases in exo deviation with increasing age regardless of head and/or gaze position. Nine of 23 presbyopic subjects gave erratic findings during fixation disparity testing and this casts doubt upon the clinical usefulness of this procedure with presbyopes.

Arrhythmogenic potential of exercise-induced myocardial ischaemia.

In a series of 300 patients following transmural infarction undergoing coronary angiography because of ischaemia in the surviving myocardium, 17 demonstrated an exercise response indicative of myocardial ischaemia in the absence of angina pectoris. The presence of ischaemia in the region of the myocardium under scrutiny was proven by: (1) ST-segment depression during bicycle-ergometry of at least 2 mm in leads without any QRS or ST-T changes at rest. (2) greater than 75% stenosis of vessels supplying the area under investigation, in addition to the vessel supplying the region of the infarction. (3) A reversible Thallium-perfusion defect on exercise. We compared those 17 patients with silent myocardial ischaemia with 21 patients with typical angina pectoris on exertion. All patients underwent 24-hour Holter monitoring, treadmill exercise testing at a target heart rate previously determined as inducing signs of myocardial ischaemia, and swimming and calisthenic programs with telemetric ECG recording. There was no close relationship between myocardial ischaemia and the occurrence of complex ventricular arrhythmias. In silent ischaemia complex ventricular arrhythmias do not occur at a higher rate than in patients with angina pectoris.