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131I scan plays a crucial role in the management of patients with differentiated thyroid cancer for the evaluation of remnant thyroid tissue, residual/recurrent metastatic disease, posttherapy tracer distribution, and response assessment to high-dose 131I therapy. Different causes secondary to physiological, pathological, and anatomical variations have been described for false-positive findings in the whole-body planar images. This case report of a patient of differentiated thyroid cancer with undocumented trauma to the left knee region a day before receiving the high-dose radioiodine therapy showed an interesting image finding of tracer uptake at unusual site in the posttherapy whole-body 131I scan.

Author(s): Muhonen, Ethan G; Mahboubi, Hossein; Moshtaghi, Omid; Sahyouni, Ronald; Ghavami, Yaser; Maducdoc, Marlon; Lin, Harrison W; Djalilian, Hamid R | Abstract: ObjectivesTo investigate false-positive findings on non-echoplanar (non-EPI) diffusion-weighted magnetic resonance imaging (DWI) in patients under surveillance post-cholesteatoma surgery.Study design, setting, subjects, and methodsA retrospective review was performed on patients diagnosed with cholesteatoma who underwent surgical resection and were then followed by serial non-EPI DWI using half-Fourier acquisition single-shot turbo spin echo (HASTE) sequence. All patients had at least two annual follow-up imaging studies.ResultsFalse-positive findings were identified in four patients. The size of the suspected lesions was 4 to 12 mm. Otoendoscopy was used during all primary cases and Argon laser was used in one case. In all cases, the entire cholesteatoma was removed, and no residual disease was detected at the end of the procedures. One patient underwent revision surgery but only cartilage graft was found in the area of concern. All patients had stable or resolved hyperintense areas in the subsequent HASTE sequences.ConclusionFalse positive findings can occur with non-EPI DWI MRI and patients need to be counseled accordingly before revision surgery. Decreasing intensity and dimension of a suspected lesion and a positive finding in an area other than the location of the initial cholesteatoma may favor a false positive. If a false positive finding is suspected when the surgeon is confident of complete resection of the cholesteatoma, an MRI can be repeated in 6 to 12 months to assess changes in the dimension and intensity of the area of concern. Cartilage grafts may cause restricted diffusion on DWI sequences.

Background The F-18 fluorodeoxyglucose positron emission/computed tomography (FDG PET/CT) has become an established diagnostic imaging for malignancy. However, there are other diseases that can also be identified with FDG, some of them are infections such as tuberculosis. Case presentation In this case report, two patients showed multiple hypermetabolic tuberculosis lesions on FDG PET/CT, with one of the patients having history of malignancy. The objective of the present case report is to emphasize the need to use other differential diagnosis techniques for tuberculosis especially in tuberculosis-endemic countries when interpreting FDG PET/CT. Conclusion By analyzing diagnostic imaging alone, there is a high chance of misinterpreting asymptomatic tuberculosis patient as having malignancy. Therefore, there is need for correlation with clinical data as well as other imaging modalities and PET/CT with more specific tracer in order to differentiate malignancy from benign disease such as tuberculosis.

Primary Epstein–Barr virus (EBV) infection is common in childhood, and dual positivity of serum EBV IgM and cytomegalovirus (CMV) IgM antibodies occur in some cases. This study aimed to evaluate the cause of EBV and CMV IgM dual positivity to determine whether it represents a false-positive finding or a true coinfection. A total of 494 children diagnosed with primary EBV infection, manifesting as infectious mononucleosis, were recruited. The diagnosis was based on positive EBV viral capsid antigen (VCA) IgM antibodies, and serum CMV IgM antibodies and liver enzymes were also evaluated in 149 subjects. Of 149 children with primary EBV infection, 40 (26.8%) had serum EBV VCA IgM and CMV IgM dual positivity. However, true CMV infection was confirmed only in 1 child of 40 (2.5%) who was positive for both serum CMV Ag and urine CMV polymerase chain reaction (PCR) and negative for serum CMV IgG antibody. Among the children with primary EBV infection, the rate of dual positivity was higher in infants and lower in adolescents (P = .013). Liver enzymes were more significantly elevated in children with dual positivity than in those with negative results for CMV IgM antibodies (P = .026), which correlated with the serum EBV and CMV IgM titers. Serum EBV and CMV IgM dual positivity are more prevalent in children with primary EBV infection than what was previously reported. Our results indicate that serum EBV and CMV IgM dual positivity represents a false-positive finding, as opposed to an actual CMV coinfection, possibly due to antigenic cross-reactivity.

Xanthogranulomatous inflammation in the spinal epidural space is extremely rare. We report a case of a 62-year-old man with a xanthogranulomatous inflammation in the spinal epidural space mistaken for lymphoma because of its avid F FDG uptake on PET/CT. This case emphasizes the need for caution when evaluating a spinal epidural mass using F FDG PET/CT as xanthogranulomatous inflammation can induce a false-positive reading on F-FDG PET/CT.

An outbreak of dengue fever occurred in Japan in August 2014. We herein report the case of a 63-year-old man who presented with a persistent fever in September 2014. Acute parvovirus B19 infection led to a false positive finding of dengue fever on a rapid diagnostic test (Panbio Dengue Duo Cassette(TM)). To the best of our knowledge, there are no previous reports of a false positive result for dengue IgM with the dengue rapid diagnostic test. We believe that epidemiological information on the prevalence of parvovirus B19 is useful for guiding the interpretation of a positive result with the dengue rapid diagnostic test.

Sclerosing Angiomatoid Nodular Transformation (SANT) is a rare benign vascular tumor of spleen. It consists of multiple angiomatoid nodules surrounded by dense fibrous tissue that often coalesces centrally to form a scar, which is considered to be a characteristic feature. These are usually asymptomatic and incidentally detected on imaging for other underlying pathology. SANTs can be 18F-Fluorodeoxyglucose (18F-FDG) avid on positron emission tomography-computed tomography (PET-CT) and thus can lead to false positive finding in oncological patients.

Objective Fluorodeoxyglucose (FDG) positron emission tomography (PET) is increasingly used to support a diagnosis of Alzheimer's disease. The aim of the present study was to evaluate a new expert system (PALZ) for the fully automated analysis of FDG PET images for diagnosis of the disease. Methods The PALZ tool is based on the detection of the typical disease pattern in FDG PET images. Its potential for this task was evaluated in 22 consecutive patients with suspected Alzheimer's disease who had been graded as positive for the pattern by an experienced reader (visual analysis supported by statistical parametric mapping (SPM)), and in 18 controls. Dependence on scanner performance was assessed by variation of the spatial resolution of the PET images. Results All the Alzheimer's disease subjects were classified as pattern-positive by the PALZ tool. Fifteen controls were classified as normal. Sensitivity and specificity for differentiation of the patients with suspected Alzheimer's disease from the controls were 100% and 83%, respectively. The false positive finding in three controls most likely was caused by differences in attenuation correction between the normal data base of the PALZ tool (cold transmission scan) and the local data sets (hot transmission scan). There was only mild dependence on spatial resolution. Conclusions The results of the present study suggest that the PALZ tool provides similar performance for the detection of the typical Alzheimer's disease pattern in FDG PET images as an experienced reader supported by SPM. The PALZ tool is fully automated, easy to use, and insensitive to the spatial resolution of the PET scanner used. Therefore, it has the potential for widespread clinical use.

Bronchial anthracofibrosis characterized by bronchostenosis associated with anthracotic pigmentation in bronchoscopic finding without a relevant history of pneumoconiosis or smoking has been recently described as a clinical entity. Radiologic finding of bronchial obstructive lesion and mediastinal lymph nodes in bronchial anthracofibrosis can be mimicking cancer. However, the metabolic characteristics of bronchial anthracofibrosis have hardly been reported. Here, we report a case of bronchial anthracofibrosis which showing hypermetabolism on F-18 FDG PET.

WEB This is a Web exclusive article. ET with 18F-FDG has been successfully used for the diagnosis, management, and follow-up of many malignant tumors. PET is particularly useful for staging of head and neck tumors and for detecting recurrence [1]. Its utility in other settings, however, such as detection of non–squamous cell cancer of the head and neck and differentiating benign salivary gland tumors from malignant ones, is limited [2, 3]. This lack of usefulness may partly be explained by the poor anatomic localization of PET combined with variable physiologic uptake of FDG in the head and neck. These factors decrease the specificity of PET for head and neck cancer and thus increase the rate of false-positive findings. Combined PET/CT scanners, which fuse the functional data of PET with the anatomic data of CT, have shown promise in the evaluation of cancer of the head and neck [4]. Non–squamous cell cancer of the head and neck, particularly salivary gland tumors, however, have not been studied extensively with either PET or combined PET/CT. In cases that have been studied, the variable uptake from salivary gland tumors often causes false-negative results [4–6]. In addition, some benign tumors of the salivary glands, particularly Warthin’s tumor, show focal FDG uptake leading to false-positive results [2]. These false-positive findings reduce the utility of PET in differentiating benign salivary gland tumors from malignant tumors. We report a case of a benign parotid oncocytoma that had marked FDG avidity on PET/CT.

Kimura disease is a chronic inflammatory disorder that occurs mainly in Asians. We present a patient with pulmonary Kimura disease assessed by whole-body 18F-FDG PET/CT examination and proved by pathologic findings. Chest x-ray detected left pulmonary hilum enlargement in a 49-year-old Chinese man. CT showed a soft tissue mass with punctate calcifications in the left pulmonary hilum, which obviously and homogeneously accumulated tracer on FDG PET. Histopathology findings showed characteristic of Kimura disease. Kimura disease should be included in the differential diagnosis of a pulmonary hilar tumor.

Testing for drugs of abuse in urine is usually performed in two steps; after initial screening positive findings are confirmed with specific chromatographic techniques. The use of different methods with different cut-off levels, may lead to variable results in a test sample containing a drug. Sixty-eight Swedish laboratories were enrolled in an external quality study and received three control samples. The laboratories were instructed to perform only in-house tests for amphetamines, benzodiazepines, cannabinoids, cocaine and opiates. Nineteen out of the 68 laboratories reported fully correct results. Thirty reported one o more false positive drug findings. One laboratory performing confirmation with gas chromatography--mass spectrometry reported a false positive finding of amphetamines in the sample containing ephedrine. Since testing for drugs of abuse in urine is a delicate matter, with both medical and legal implications, such testing should be performed with a zero rate of false positive results. Routine use of specific methods for confirmation should be used since performance of these laboratories was better in this study. It is concluded that there is a need to continuously measure the level of quality of laboratories by a program for external quality control.

Purpose: To compare the performance of virtual and conventional colonoscopy for the detection of colorectal polyps using a multislice spiral CT scanner (MSCT). Materials and Methods: 48 patients (20 women, 28 men, mean age 61.5 5 years) with clinical indication for conventional colonoscopy were prospectively studied using a MSCT (Somatom Volume Zoom, Siemens, Forchheim). Examination was performed after standard oral preparation for colonoscopy and colonic distension with room air and i.v. butylscopolamin. Images were obtained in prone and supine position using a detector configuration of 4 × 1 mm, a table feed of 5 mm/rotation at 140 mAs and 120 kV. Slice thickness and reconstruction increment were 3 and 1.5 mm, respectively. CT data were assessed by two blinded radiologists on a Vitrea workstation (Vital Images, USA) using a software with multiplanar and volume-rendering capabilities. Results: 33 patients had normal findings on conventional colonoscopy. In 15 patients a total of 30 polyps and one carcinoma with stenosis were identified. MSCT-colonography identified the carcinoma and 23 polyps (77%). 3 of 3 polyps were 10 mm or more (100%), 6 of 7 were 5.1 to 9.9 mm (86%) and 14 of 20 were 5 mm or smaller (70%). There were 13 false positive findings for polyps (10 lesions < 6 mm in 5 patients) and no false positive finding of carcinoma. Conclusions: MSCT colonography allows accurate detection of polyps larger than 10 mm. Compared to published results of single-slice CT, multislice CT colonography increases the rate of detection of small colorectal polyps in particular. However, false positive results still remain a problem.

We report herein two cases of suture granuloma showing focal intense 2-deoxy-2-[18F]fluoro- d -glucose (FDG)-uptake in positron emission tomography (PET). Follow-up FDG-PET after surgical intervention for head and neck cancer revealed lesions with high FDG-uptake, which were highly suspected of being a recurrent tumor. The lesions were subjected to excisional biopsy for definitive diagnosis. Histopathological examination proved them to be suture granulomas caused by non-absorbable silk sutures. It should be emphasized that suture granulomas can show false-positive findings on FDG-PET, thus requiring differential diagnosis from recurrent tumors.

Background: Emergency physicians commonly perform Focused Assessment with Sonography for Trauma (FAST) examinations to evaluate for free intraperitoneal fluid. Many ultrasound findings can be misinterpreted as free fluid, resulting in false-positive FAST examinations. Objectives: To describe a previously unreported ultrasound finding that can be misinterpreted as free intraperitoneal fluid. Case Report: A 32-year-old man was stabbed in the left upper abdomen. A FAST examination was performed and a right perinephric fat pad was interpreted as showing free fluid in Morison's pouch. After transfer to a trauma center, a repeat FAST examination revealed no signs of intraperitoneal free fluid. Wound exploration showed no signs of penetration into the peritoneal cavity. Conclusions: When performing a FAST examination, a wedge-shaped hypoechoic area in Morison's pouch that is bounded on both sides by echogenic lines (the “FAST Double-Line Sign”) is likely to represent perinephric fat and may result in a false-positive FAST examination.

The FAST exam has become the current standard for free intraperitoneal fluid determination in most emergency departments. Knowledge of false negative and false positive findings is imperative to improve accuracy. We detail a case in which an important false positive findings previously not discussed in the medical literature was noted. The ability of the physician to recognize the "gastric fluid" sign and make the adjustments accordingly could improve the specificity of the FAST exam, preventing non-therapeutic laparotomies.

This case report describes a patient who presented to the Emergency Department (ED) after a high-speed motor vehicle crash (MVC), whose initial ultrasound examination was interpreted as being positive for fluid in Morison’s pouch. Subsequent ultrasound examinations and computed tomography scans further delineated this finding to be fluid-filled bowel juxtaposed between the liver and right kidney. With greater implementation of ED ultrasound, it is important to identify entities that cause false-positive and false-negative examinations.

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.

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

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 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.