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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.

Scanning oncological patients with 18F-fluorodeoxyglucose (18F-FDG) for their disease staging, evaluation of treatment response, and monitoring/management has become a standard of care. The use of the radioactive fluorine in the FDG molecule helps establish cell/tissue lines high on glucose consumption and hence metabolically active. Abnormalities are detected on the scan as areas of increased uptake. However, these areas of increased (hot) uptakes do not necessarily translate into a pathological finding. A comprehensive knowledge of the uptakes of the tracer and the potential “pitfalls” that may be associated with them should be known and kept in mind during scan reading. One such pitfall is the “hot clot” or “pulmonary emboli,” and we report two such cases encountered at our setup and discuss their causes and how they should be identified and avoided.

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.

We present two cases of cholesteatoma and one false positive finding in non-EP DW MRI in order to highlight the differential diagnosis in imaging and emphasize the need to discuss the findings with the otologic surgeon. The first case demonstrates different MRI signal patterns encountered in a patient with cholesteatoma. The second report is a rare case of supralabyrinthine cholesteatoma with atypical clinical presentation. The third case presents a rare but important false positive finding in non-EP DW MRI. Clinical and imaging findings are discussed taking into account the current literature.

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.

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.

Laparoscopy and magnetic resonance imaging (MRI) are competetive tools in the diagnostic of non-palpable testis. Advantages and disadvantages of this methods will be demonstrate. 29 boys investigated for this indication with MRI. In case MRI failed to locate the testis laparoscopy was performed with a new miniaturized set of pediatric instruments (1.9 mm optic). The aim of laparoscopy was the identification of the spermatic duct and vessels and their topographic relation to the internal inguinal ring. All findings were verified by open surgical procedures. MRI revealed 10 inguinal and 7 abdominal testis. There was no false positive finding. In 12 boys MRI showed no testis. 4 cases were correct negative, 8 cases were false negative (32 %). In these 8 MRI-negative patients laparoscopy revealed 7 inguinal and 1 abdominal testis. The optical quality of the mini-telescope was sufficient for a 100 % correct diagnosis. Laparoscopy related complications did not occur. Laparoscopy proved to be a powerful low risk diagnostic method in non- palpable testis with high senitivity and specifity (100 % correct positive, 0 % false negative). Therefore lapraroscopy is recommended as primary diagnostic access for this indication. In the same anesthesia a optimal therapy is possible. Nevertheless a positive MRI-finding locates the testis reliably, whereas a negative finding always needs further exploration because testis might have been missed.

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.

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.

The value of colour Doppler sonography in the diagnosis of renal artery stenosis has been studied retrospectively. 17 patients were examined (34 main renal arteries and 7 accessory renal arteries; ages 37 to 84 years; 7 males and 10 females). We studied 1) ability to study the main renal arteries, 2) visibility of accessory renal arteries and 3) the sensitivity and specificity of colour Doppler sonography for the diagnosis of renal artery stenosis. The results were compared with intraarterial angiography. Demonstration of the main renal arteries with colour Doppler sonography was possible in 23 of the 34 vessels. Not a single of the 7 accessory renal arteries was demonstrated by colour Doppler sonography. Of 8 angiographically demonstrated stenoses (more than 50% narrowing) 2 were missed by colour Doppler sonography. One stenosis was correctly diagnosed and 5 were incorrectly evaluated by sonography. 16 out of 18 angiographically normal main renal arteries were correctly evaluated by colour Doppler sonography but 2 showed a false positive finding. This results in a sensitivity of 17% and a specificity of 89% per kidney. Colour Doppler sonography cannot be recommended as a screening method for renal artery stenosis in view of its limited accuracy.

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.

Purpose: To compare the influence of visual and acoustical CAD markers on radiologist’s performance with regard to suggestive and distractive effects. Materials and methods: Ten radiologists analyzed 150 pictures of ches t CT slices. Every picture contained a visual CAD marker. 100 pictures showed one nodule: CAD marker marked this in 50 cases and in 50 cases a false positive finding (f.p.). The other 50 cases showed no nodule but an f.p. marker. After 3 years same images were presented to thirteen radiologists with only a sound as CAD marker. 55 of 150 images were marked, 30 true positive and 25 f.p. Sensitivity and f.p. rate were calculated for both marker ty pes. Significance between sens itivities and f.p. rates were calculated by multiple-ana lysis-of-variance (MANOVA). Results: Without CAD mean sensitivity resp. f.p. were 57.7% /.13 . In case of correct optical resp. acoustical marker sensitivity increased to 75.6% resp. 63.1%. For incorrect se t marker mean f.p. rate increased to .31 resp. .24. MANOVA showed that marker’s correctness highly significan tly influenced sensitivity (p

Purpose: The efficiency of the detection of pulmonary nodules by a radiologist with the help of CAD is influenced by the user interface of the system. Marker with a visually dominant appearance may distract the radiologist from other parts of the screen. Purpose was to analyse the influence of different CAD markers on radiologist's performance. Materials and methods: 10 radiologists analysed 150 pictures of chest CT slices. Every picture contained a CAD marker; five different types of markers were used - each respectively on 30 pictures (1: thick walled square, 2: thin walled circle, 3: small arrow, 4: pixel sized point on nodule, 5: very subtle change of colour). One hundred images contained one nodule: CAD markers marked this finding in 50 cases; in 50 cases a false positive finding was marked instead. The remaining 50 images contained no nodule but a marker of a false positive finding. The radiologists had to decide for each image if there was a nodule visible and either click on the nodule or on a button "no finding". Sensitivity and specificity were calculated for each marker type. Results: Mean sensitivity was 59%, 62%, 64%, 65% and 64% for marker 1 to 5, respectively. Specificity was 50%, 51%, 64%, 45% and 67%. In the cases with false positive findings sensitivity for detection of the unmarked nodule was 41%, 58%, 59%, 49% and 54%. New work to be presented: The study shows that the marker type influences radiologist's sensitivity and distraction from other findings. Conclusion: Of the tested markers a small arrow was most efficient for the presentation of the results to the radiologist.

The purpose of the presented study was to determine the impact of two different CAD systems used as concur-rent reader for detection of actionable nodules (>4 mm) on the interpretation of chest CT scans during routine reporting. Fifty consecutive MDCT scans (1 mm or 1.25 mm slice thickness, 0.8 mm reconstruction increment) were se-lected from clinical routine. All cases were read by a resident and a staff radiologist, and a written report was available in the radiology information system (RIS). The RIS report mentioned at least one actionable pulmonary nodule in 18 cases (50%) and did not report any pulmonary nodule in the remaining 32 cases. Two different recent CAD systems were independently applied to the 50 CT scans as concurrent reader with two radiologists: Siemens LungCare NEV and MEDIAN CAD-Lung. Two radiologists independently reviewed the CAD results and determined if a CAD result was a true positive or a false positive finding. Patients were classified into two groups: in group A if at least one actionable nodule was detected and in group B if no actionable nodules were found. The effect of CAD on routine reporting was simulated as set union of the findings of routine reporting and CAD thus applying CAD as concurrent reader. According to the RIS report group A (patients with at least one actionable nodule) contained 18 cases (36% of all 50 cases), and group B contained 32 cases. Application of a CAD system as concurrent reader resulted in detec-tion of additional CT scans with actionable nodules and reclassification into group A in 16 resp. 18 cases (radi-ologist 1 resp. radiologist 2) with Siemens NEV and in 19 resp. 18 cases with MEDIAN CAD-Lung. In seven cases MEDIAN CAD-Lung and in four cases Siemens NEV reclassified a case into group A while the other CAD system missed the relevant finding. Sensitivity on a nodule (>4 mm) base was .45 for Siemens NEV and .55 for MEDIAN CAD-Lung; the difference was not yet significant (p=.077). In our study use of CAD as second reader in routine reporting doubled the percentage of patients with actionable nodules larger than 4 mm.

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 commonly seen in positron emission tomography computed tomography imaging. One of the most common false positive finding is uptake of fluorodeoxyglucose in brown adipose tissue. Herein, we report two cases with incidentally detected hibernomas-a brown fat containing tumor with metabolic activity.

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.

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).

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.

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.