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False positive findings are a common problem in whole genome association studies. In this commentary we show that nothing is gained by randomly splitting a data sample to two equal sized subsets, where the first data subset is used for explorative purposes and the other sub set is used to confirm the findings in the first subset. We compare the random splitting procedure to using the full data sample for analysis, by using a Bayesian perspective with consideration taken to prior probability of a false positive finding.

PET/CT is a widely accepted imaging modality in the diagnosis and staging of lymphoma because of the increased FDG uptake commonly detected in malignant lesions. However, various causes of false-positive FDG localization have been described, including in nonmalignant lymph nodes. We report a patient with a history of Hodgkin lymphoma who presented with bilateral axillary lymphadenopathy, which was intensely FDG-avid on PET/CT imaging. Biopsy of lymph nodes from both axillae revealed benign follicular hyperplasia. Follicular hyperplasia is a potential false-positive finding on PET/CT imaging, and obtaining pathologic confirmation of malignancy should be considered before treatment.

It has been noticed that the postmortem liver samples gives a positive result for amphetamines, although it is proved that the person has not previously consumed amphetamines. Postmortem liver samples are of great importance since they contain many valuable specimens in higher concentration then in some other biological samples. It was observed that liver tissue from persons found several days after death occur contains amphetamines. Purpose - The purpose of this study is to determine conditions that are responsible for amphetamine false positive finding in postmortem liver samples. Methods- Postmortem liver samples, which should be toxicologically processed, and the previous test gave negative amphetamine findings, are divided into several samples with identical weight and were subjected to the influence of different temperature in different time period. At various time intervals samples are being analyzed and determent qualitatively and quantitative by gas chromatography- mass spectrometry technique (GC/MS). Results - Liver samples with amphetamine negative findings, gave positive results after few days at temperature of 32, 5 degree Celsius. It was noted that the alcohol concentration has an effect on amphetamine occurrence.

Nearly 13 years ago inflammation imaging using labeled white blood cells (WBCs) has been introduced in clinical nuclear medicine.

Varicocele is the most frequent operable cause of male infertility. It is often difficult to diagnose small lesions merely by clinical examination. The fact that a measurable rise of scrotal temperature occurs in a certain number of infertile patients has helped to extend thermography also to the detection of such cases (Comhaire et al., 1976; Zorgniotti and MacLeod, 1973).

Identification of genetic variants affecting complex traits such as obesity is confounded by many types of bias, especially when effect sizes are small. Given our findings of a positive association between rs7566605 and body mass index in four out of five separate samples, a false positive finding cannot be ruled out with certainty but seems unlikely. Meta-analyses of multiple large studies will help refine the estimate of the effects of rs7566605 on body mass index.

Somatostatin receptor scintigraphy with In-111 octreotide has shown excellent accuracy in many neuroendocrine tumors, including carcinoid. Substantial gallbladder activity may be present on early images; however, the administration of a fatty meal and/or the effect of time generally results in littl

CT was carried out in 50 patients with clinical suspicion of hyperparathyroidism, in order to localise the adenoma. In 45 patients, the diagnosis was confirmed at operation and adenomas or hyperplastic glands were removed. In the remaining five patients the diagnosis was not confirmed at operation, nor by the subsequent clinical course. On four occasions, CT correctly turned out to be negative and in one patient a false positive finding was obtained. Amongst the 45 patients, a total of 59 enlarged glands (adenomas or hyperplastic glands) were found at operation and removed. Pre-operative CT was positive and correct in 78% and negative and incorrect in 22%. Of eight adenomas in the mediastinum, seven could be recognised pre-operatively. Previous operations on the neck did not reduce diagnostic accuracy. The techniques and results are described and discussed.

Between 1965 and 1968, 6500 lymphograms were performed at the University of Gottingen. Amongst these, there were 412 patients with malignant testicular tumours. In 81 patients the results of lymphography could be checked histologically. There was agreement between the lymphographic and histological findings in 65 patients (80.3%), sensitivity of 98.1% (51 out of 52) and specificity of 48.3% (14 out of 29). In 50 patients CT was performed in addition. The findings agreed in 31 cases; in eight patients lymphangiography resulted in a false positive finding and CT was incorrect in 12 patients. In all patients with proven retroperitoneal metastases, one or the other method produced a correct diagnosis.

The specificity of radioimmunoassay of aflatoxin B1 was tested. Relative cross-reactivity of used antiserum with aflatoxins B1, B2, G1, G2 and M1 was found to be 100%, 24%, 44.2%, 10.3%, and 1.4%, respectively. The interference of coumarin, albumins, steroids and ethylvanilin was estimated also in radioimmunoassay of aflatoxin B1. Thus these compounds may cause a false positive finding of aflatoxin B1.

Selective venous sampling for parathormone estimations has become an important method in the diagnosis of primary hyperparathyroidism and, together with thyroid phlebography, is an accurate means for localising hormone active parathyroid tissue. Thirty-three patients were examined by this technique and in 25 of these an exploration was carried out subsequently. Twenty-one had primary hyperparathyroidism. In one case hormone analysis lead to a false positive finding. In 18 of these 21 patients, the hormone-active parathyroid tissue was correctly localised. Phlebography showed evidence of an adenoma in five patients, but is of most use for localising the source of the hormone.

Many chemicals shown to be teratogenic in laboratory animals are not known to be teratogenic in humans. However, it remains to be determined if the unresponsiveness of humans is due to lessened sensitivity, to generally subteratogenic exposure levels, or to the lack of an appropriate means of identifying human teratogens. On the other hand, with the exception of the coumarin anticoagulant drugs, those agents well accepted as human teratogens have been shown to be teratogenic in one or more laboratory species. Yet, no single species has clearly distinguished itself as being more advantageous in the detection of human teratogens over any other. Among the species used for testing, the rat and mouse most successfully model the human reaction, but the rabbit is less likely than other species to give a false positive finding. Among species less commonly used for testing, primates offered a higher level of predicability than others. Regarding concordance of target malformations, the mouse and rat produced the greatest number of concordant defects, but they also were responsible for the most noncorcordant responses as well. Since no other species is clearly more predictive of the human response, it is concluded that safety decisions should be based on all reproductive and developmental toxicity data in light of the agent's known pharmacokinetic, metabolic and toxicologic parameters.

A consecutive series of 301 ultrasonically guided fine needle aspiration biopsies of renal masses was reviewed. The retrieval rate was 95 per cent and a correct cytological diagnosis was established in 82 per cent of the cases. There were 14 false positive aspirates, for a predictive value of a malignant aspirate of only 93 per cent. All false positive results were misinterpreted as relatively well differentiated adenocarcinoma. We conclude that renal fine needle aspiration biopsy may add information but the risk of a false positive finding must always be considered.

The crucial considerations in selecting a research design to test drug efficacy include: 1. Validity: If the drug is not effective, is the chance of a false positive finding less than 5% or 1%? 2. Power Efficiency: If the drug is effective, is the chance of a true positive finding reasonably high? 3. Feasibility and Cost: Can the design be reasonably implemented in the research situation for which it is proposed? 4. Clinical Value: Does the design yield information sufficient in extent and quality to serve as a basis for evaluation of the clinical value of the drug?

The measurement and interpretation of nocturnal penile tumescence (NPT) studies depend on appropriate measurement techniques, knowledge of the conditions during which NPT was recorded. and a lack of preconceived notions about the relationship of penile circumference to penile rigidity. This case report illustrates several of the most common problems in the measurement and interpretation of NPT that could result in a false positive finding.

1. Residual barium in the bowel, when superimposed over the liver, can produce localized areas of decreased uptake on a scan and thereby a false positive finding. This was detected clinically and confirmed by experimental means.2. A scout roentgenogram of the abdomen is recommended immediately prior to the scanning of abdominal organs.