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John Seibyl - One of the best experts on this subject based on the ideXlab platform.
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individual reader diagnostic performance and between reader agreement in assessment of subjects with parkinsonian syndrome or dementia using 123i ioflupane injection datscan imaging
The Journal of Nuclear Medicine, 2014Co-Authors: John Seibyl, Donald G Grosset, Nin Bajaj, Andreas Kupsch, Zuzana Walker, Jan Booij, D C Costa, Robert A Hauser, Jacques Darcourt, Kenneth MarekAbstract:Establishing an early, accurate diagnosis is fundamental for appropriate clinical management of patients with movement disorders or dementia. Ioflupane 123I Injection (DaTscan, 123I-ioflupane) is an important adjunct to support the clinical diagnosis. Understanding individual-reader diagnostic performance of 123I-ioflupane in a variety of clinical scenarios is essential. Methods: Sensitivity, specificity, interreader, and intrareader data from 5 multicenter clinical studies were reviewed. The different study designs offered an assortment of variables to assess the effects on the diagnostic performance of 123I-ioflupane: on-site versus 3–5 blinded image readers, number of image evaluations, early/uncertain versus late/confirmed clinical diagnosis as reference standard, and subjects with movement disorders versus dementia. Results: Eight hundred eighteen subjects had individual-reader efficacy data available for analysis. In general, sensitivity and specificity were high and comparable between on-site versus blinded independent readers. In subjects with dementia, when the clinical diagnosis was made at month 12 versus baseline, specificity improved from 77.4%–91.2% to 81.6%–95.0%. In subjects with movement disorders, this effect was observed to an even greater extent, when diagnostic performance using month-18 diagnosis as a reference standard (sensitivity, 67.0%–73.7%; specificity, 75.0%–83.3%) was compared versus month-36 diagnosis (77.5%–80.3% and 90.3%–96.8%, respectively). Diagnostic performance was similar in subjects with dementia (74.4%–89.9% and 77.4%–95.0%, respectively) and subjects with movement disorders (67.0%–97.9% and 71.4%–98.4%, respectively). In most of the comparisons, between-reader agreement was very good (almost perfect), with κ ranging from 0.81 to 1.00. Within-reader agreement, measured in 1 study, was 100% for 3 blinded readers. Conclusion: Individual-reader diagnostic performance, as assessed by measuring sensitivity and specificity of 123I-ioflupane to detect the presence or absence of striatal dopaminergic deficit, using the clinical diagnosis as a reference standard, was high in subjects with either movement disorders or dementia and was similar in on-site readers versus blinded analyses. Between- and within-reader agreements were very good (almost perfect). Longer follow-up between imaging and clinical diagnosis improved the diagnostic accuracy, most likely due to improvement in the clinical diagnosis reference standard, rather than changes in reader accuracy.
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efficacy and reliability of the visual assessment of 18f florbetaben pet scans in the detection of beta amyloid neuritic plaques in the brain
The Journal of Nuclear Medicine, 2014Co-Authors: Osama Sabri, Ana M Catafau, Andrew W Stephens, Henryk Barthel, Kenji Ishii, Christopher C Rowe, James B Leverenz, Schulzschaefer Walter, Marwan N Sabbagh, John SeibylAbstract:244 Objectives A standardized visual assessment of amyloid PET scans compared to histopathology is required for evaluation of tracer efficacy. Pronounced atrophy and other brain abnormalities can compromise image interpretation in elderly end-of-life subjects. In this large histopathology study, the efficacy and reliability of the visual assessment of florbetaben (FBB) PET scans for the detection of beta-amyloid neuritic plaques was assessed using both in-person and electronically trained blinded readers. Methods FBB PET scans from 82 deceased patients were assessed by 3 in-person trained readers and by 5 independent readers trained with the electronic training module intended to be used as part of the future training for readers. PET images were read in grey scale on the axial plane only and without access to structural imaging (CT, MR). For each reader, sensitivity and specificity were calculated. Neuritic beta amyloid plaques detected by a combination of Bielschowsky silver stain and immunohistochemistry were assessed by a histopathology consensus panel and served as standard of truth. Results For the in-person trained readers, median sensitivity was 98% (range 95%-98%) and similar high sensitivity was obtained by the 5 electronically trained readers: median sensitivity 96%, (range 91-100%). The median specificity in the in-person trained reader group was 92% (range 89%-92%) and was comparable to the electronic media trained group (median 89%, range 54%-92%). Conclusions The visual assessment method of FBB images was proven to be robust even in challenging scans from elderly end-of-life subjects. High sensitivity and specificity were observed independent of the reader training method employed. Research Support Piramal Imaging (Berlin, Germany)
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reliability reproducibility and efficacy of the 18f florbetaben β amyloid pet scan visual assessment method as trained via a computer based instructional tool
The Journal of Nuclear Medicine, 2013Co-Authors: John Seibyl, Andrew W Stephens, Henryk Barthel, Cornelia Reininger, Osama SabriAbstract:300 Objectives The primary objective of this study was to assess the reproducibility (inter- and intra-reader agreement) of the visual assessment of positron emission tomography (PET) scans from a subject population that closely represents the future clinical use population using 18F florbetaben PET scans pooled from various clinical studies. Methods PET images from 460 18F florbetaben injections from Phase 1, 2, and 3 clinical trials were pooled and randomly assigned for consecutive, blinded visual assessment by five independent blinded nuclear medicine physicians. Images were acquired in subjects with the diagnoses of probable and possible AD (mild to moderate), other dementia subtypes, MCI, and healthy volunteers (HVs). Readers had limited or no prior experience with amyloid PET visual interpretation and were trained on a computer web-based training tool. 10% of images were randomly re-presented to readers for the assessment of intra-reader agreement. Kappa estimates with upper and lower confidence limits were calculated to analyze the agreement across all 5 blinded readers. Results The primary endpoint showed a kappa value of 0.787 (95 % CI: 0.750 - 0.824%) across all five readers. The inter-reader agreement was high in all reader pairs, the highest was 0.865 (95% CI: 0.819 - 0.911%) between Readers 1 and 3 and the lowest was 0.677 (95% CI: 0.609 - 0.744%) between Readers 2 and 5. Conclusions A computer-based web training tool provides high inter- and intra-rater reliability and efficacy in the visual assessment of 18F florbetaben PET among inexperienced readers of scans from a clinically-relevant patient cohort. Research Support Bayer Healthcare/Piramal Imaging, Berlin (Germany)
Andrew W Stephens - One of the best experts on this subject based on the ideXlab platform.
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performance of 18f florbetaben pet image reading training in japanese language
The Journal of Nuclear Medicine, 2016Co-Authors: Santiago Bullich, Ana M Catafau, Michio Senda, Victoria Khodaverdiafaghi, Andrew W StephensAbstract:1822 Objectives The efficacy of the visual assessment of 18F-Florbetaben (FBB) positron emission tomography (PET) scans against histopathology confirmation of presence or absence of β-amyloid neuritic plaque in the brain has been previously established [1]. The aim of this study was to assess the performance of the 18F-FBB PET image reading training in the Japanese language, as it is intended to be used as part of the future training for nuclear medicine physicians in Japan. Methods Five blinded Japanese readers without previous experience reading FBB images were trained in-person by an expert Japanese nuclear medicine physician using the 18F-FBB PET image reading training materials in the Japanese language. PET images of 50 subjects (mostly Japanese) from a number of studies were pooled (n=17 patients diagnosed with Alzheimer’s disease, n=17 Healthy Volunteers and n=16 subjects with Mild Cognitive Impairment), and randomly assigned for blinded visual assessment using the image assessment criteria defined by the sponsor company. These images were previously assessed with the same criteria by 5 independent non-Japanese, electronically trained blinded readers as 25 positive and 25 negative scans, which was used as reference. The final assessment was binary as positive (β-amyloid present) or negative (β-amyloid absent). Percent agreement between the results of each Japanese reader with the majority results of the non-Japanese readers was separately calculated. Percent agreement among majority reads from both groups was calculated. Inter-reader agreement was assessed by calculating Fleiss’s kappa across all five readers and Cohen’s kappa between each pair of readers. Intra-reader agreement was assessed by calculating Cohen’s kappa values per reader for a re-read of 10 randomly selected cases from the image data set. Results The percent agreement between the majority read of the non-Japanese readers and the majority read of the Japanese readers was 100.0% (95% CI: 92.9 - 100.0). A very high agreement between individual Japanese readers and the majority read of non-Japanese readers was observed (mean (range): 96.4 (86-100) %); (100% (n=3), 96% (n=1) and 86% (n=1)). Excellent inter-reader agreement was observed; kappa across 5 blinded readers was 0.87 (95% CI: 0.78 - 0.96). The average inter-reader agreement between reader pairs was 0.87 (range: 0.72 - 1.00). The mean percent of intra-reader agreement was 90% (range: 70-100%). Mean intra-reader variability for each of the five blinded readers was 0.78 (range: 0.34-1.00). Conclusions This study confirms that readers taught by the in-person training in the Japanese language perform similar to non-Japanese readers in the visual assessment of FBB scans. The visual assessment method and the in-person training in the Japanese language is appropriate for clinical use in Japan. 1. Sabri, O., et al., Florbetaben PET imaging to detect amyloid beta plaques in Alzheimer disease: Phase 3 study. Alzheimer9s & Dementia, 2015. 11(8): p. 964-974.
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efficacy and reliability of the visual assessment of 18f florbetaben pet scans in the detection of beta amyloid neuritic plaques in the brain
The Journal of Nuclear Medicine, 2014Co-Authors: Osama Sabri, Ana M Catafau, Andrew W Stephens, Henryk Barthel, Kenji Ishii, Christopher C Rowe, James B Leverenz, Schulzschaefer Walter, Marwan N Sabbagh, John SeibylAbstract:244 Objectives A standardized visual assessment of amyloid PET scans compared to histopathology is required for evaluation of tracer efficacy. Pronounced atrophy and other brain abnormalities can compromise image interpretation in elderly end-of-life subjects. In this large histopathology study, the efficacy and reliability of the visual assessment of florbetaben (FBB) PET scans for the detection of beta-amyloid neuritic plaques was assessed using both in-person and electronically trained blinded readers. Methods FBB PET scans from 82 deceased patients were assessed by 3 in-person trained readers and by 5 independent readers trained with the electronic training module intended to be used as part of the future training for readers. PET images were read in grey scale on the axial plane only and without access to structural imaging (CT, MR). For each reader, sensitivity and specificity were calculated. Neuritic beta amyloid plaques detected by a combination of Bielschowsky silver stain and immunohistochemistry were assessed by a histopathology consensus panel and served as standard of truth. Results For the in-person trained readers, median sensitivity was 98% (range 95%-98%) and similar high sensitivity was obtained by the 5 electronically trained readers: median sensitivity 96%, (range 91-100%). The median specificity in the in-person trained reader group was 92% (range 89%-92%) and was comparable to the electronic media trained group (median 89%, range 54%-92%). Conclusions The visual assessment method of FBB images was proven to be robust even in challenging scans from elderly end-of-life subjects. High sensitivity and specificity were observed independent of the reader training method employed. Research Support Piramal Imaging (Berlin, Germany)
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reliability reproducibility and efficacy of the 18f florbetaben β amyloid pet scan visual assessment method as trained via a computer based instructional tool
The Journal of Nuclear Medicine, 2013Co-Authors: John Seibyl, Andrew W Stephens, Henryk Barthel, Cornelia Reininger, Osama SabriAbstract:300 Objectives The primary objective of this study was to assess the reproducibility (inter- and intra-reader agreement) of the visual assessment of positron emission tomography (PET) scans from a subject population that closely represents the future clinical use population using 18F florbetaben PET scans pooled from various clinical studies. Methods PET images from 460 18F florbetaben injections from Phase 1, 2, and 3 clinical trials were pooled and randomly assigned for consecutive, blinded visual assessment by five independent blinded nuclear medicine physicians. Images were acquired in subjects with the diagnoses of probable and possible AD (mild to moderate), other dementia subtypes, MCI, and healthy volunteers (HVs). Readers had limited or no prior experience with amyloid PET visual interpretation and were trained on a computer web-based training tool. 10% of images were randomly re-presented to readers for the assessment of intra-reader agreement. Kappa estimates with upper and lower confidence limits were calculated to analyze the agreement across all 5 blinded readers. Results The primary endpoint showed a kappa value of 0.787 (95 % CI: 0.750 - 0.824%) across all five readers. The inter-reader agreement was high in all reader pairs, the highest was 0.865 (95% CI: 0.819 - 0.911%) between Readers 1 and 3 and the lowest was 0.677 (95% CI: 0.609 - 0.744%) between Readers 2 and 5. Conclusions A computer-based web training tool provides high inter- and intra-rater reliability and efficacy in the visual assessment of 18F florbetaben PET among inexperienced readers of scans from a clinically-relevant patient cohort. Research Support Bayer Healthcare/Piramal Imaging, Berlin (Germany)
Osama Sabri - One of the best experts on this subject based on the ideXlab platform.
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efficacy and reliability of the visual assessment of 18f florbetaben pet scans in the detection of beta amyloid neuritic plaques in the brain
The Journal of Nuclear Medicine, 2014Co-Authors: Osama Sabri, Ana M Catafau, Andrew W Stephens, Henryk Barthel, Kenji Ishii, Christopher C Rowe, James B Leverenz, Schulzschaefer Walter, Marwan N Sabbagh, John SeibylAbstract:244 Objectives A standardized visual assessment of amyloid PET scans compared to histopathology is required for evaluation of tracer efficacy. Pronounced atrophy and other brain abnormalities can compromise image interpretation in elderly end-of-life subjects. In this large histopathology study, the efficacy and reliability of the visual assessment of florbetaben (FBB) PET scans for the detection of beta-amyloid neuritic plaques was assessed using both in-person and electronically trained blinded readers. Methods FBB PET scans from 82 deceased patients were assessed by 3 in-person trained readers and by 5 independent readers trained with the electronic training module intended to be used as part of the future training for readers. PET images were read in grey scale on the axial plane only and without access to structural imaging (CT, MR). For each reader, sensitivity and specificity were calculated. Neuritic beta amyloid plaques detected by a combination of Bielschowsky silver stain and immunohistochemistry were assessed by a histopathology consensus panel and served as standard of truth. Results For the in-person trained readers, median sensitivity was 98% (range 95%-98%) and similar high sensitivity was obtained by the 5 electronically trained readers: median sensitivity 96%, (range 91-100%). The median specificity in the in-person trained reader group was 92% (range 89%-92%) and was comparable to the electronic media trained group (median 89%, range 54%-92%). Conclusions The visual assessment method of FBB images was proven to be robust even in challenging scans from elderly end-of-life subjects. High sensitivity and specificity were observed independent of the reader training method employed. Research Support Piramal Imaging (Berlin, Germany)
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reliability reproducibility and efficacy of the 18f florbetaben β amyloid pet scan visual assessment method as trained via a computer based instructional tool
The Journal of Nuclear Medicine, 2013Co-Authors: John Seibyl, Andrew W Stephens, Henryk Barthel, Cornelia Reininger, Osama SabriAbstract:300 Objectives The primary objective of this study was to assess the reproducibility (inter- and intra-reader agreement) of the visual assessment of positron emission tomography (PET) scans from a subject population that closely represents the future clinical use population using 18F florbetaben PET scans pooled from various clinical studies. Methods PET images from 460 18F florbetaben injections from Phase 1, 2, and 3 clinical trials were pooled and randomly assigned for consecutive, blinded visual assessment by five independent blinded nuclear medicine physicians. Images were acquired in subjects with the diagnoses of probable and possible AD (mild to moderate), other dementia subtypes, MCI, and healthy volunteers (HVs). Readers had limited or no prior experience with amyloid PET visual interpretation and were trained on a computer web-based training tool. 10% of images were randomly re-presented to readers for the assessment of intra-reader agreement. Kappa estimates with upper and lower confidence limits were calculated to analyze the agreement across all 5 blinded readers. Results The primary endpoint showed a kappa value of 0.787 (95 % CI: 0.750 - 0.824%) across all five readers. The inter-reader agreement was high in all reader pairs, the highest was 0.865 (95% CI: 0.819 - 0.911%) between Readers 1 and 3 and the lowest was 0.677 (95% CI: 0.609 - 0.744%) between Readers 2 and 5. Conclusions A computer-based web training tool provides high inter- and intra-rater reliability and efficacy in the visual assessment of 18F florbetaben PET among inexperienced readers of scans from a clinically-relevant patient cohort. Research Support Bayer Healthcare/Piramal Imaging, Berlin (Germany)
S.e. Sarma - One of the best experts on this subject based on the ideXlab platform.
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hiq a hierarchical q learning algorithm to solve the reader collision problem
Symposium on Applications and the Internet, 2006Co-Authors: Daniel W. Engels, S.e. SarmaAbstract:HiQ is a hierarchical, online learning algorithm that finds dynamic solutions to the reader collision problem in RFID systems. When the transmissions from one reader interfere with the operation of another reader, a reader collision occurs. The objective of the reader collision problem is to minimize the reader collisions experienced by RFID readers while using the minimum number of frequencies and using the minimum total time for all readers to communicate successfully. HiQ attempts to minimize reader collisions by learning the collision patterns of the readers and by effectively assigning frequencies over time to ensure neighboring readers do not experience collisions from one another. HiQ is arranged hierarchically with distributed, local control. The algorithm is based on a type of reinforcement learning called Q-learning, which is used to determine frequency and time assignments. Through repeated interaction with the system, Q-learning attempts to discover an optimum frequency assignment over time. We show that HiQ finds optimal or near optimal solutions to the reader collision problem.
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Colorwave: an anticollision algorithm for the reader collision problem
2004Co-Authors: Jeffrey Waldrop, Daniel W. Engels, S.e. SarmaAbstract:We present the Colorwave algorithm, a simple, distributed, on-line algorithm for the reader collision problem in radio frequency identification (RFID) systems. RFID systems are increasingly being used in applications, such as those experienced in supply chain management, which require RFID readers to operate in close proximity to one another. Readers physically located near one another may interfere with one another's operation. Such reader collisions must be minimized to ensure the correct operation of the RFID system. The Colorwave algorithm yields on-line solutions that are near the optimal static solutions. The dynamic nature of the algorithm enables the RFID system to automatically adapt to changes in the system and in the operating environment of the system.
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the reader collision problem
Systems Man and Cybernetics, 2002Co-Authors: Daniel W. Engels, S.e. SarmaAbstract:We introduce the reader collision problem, the problem of allocating frequencies over time to radio frequency identification (RFID) tag readers such that their interference with one another is minimized. RFID systems are comprised of readers and tags. Readers communicate with tags using radio frequency (RF) signaling to obtain the identifier and other data stored on the tag. A reader may interfere with the operation of other readers in the RFID system. The two principal types of reader-to-reader interference are frequency interference, two or more readers communicating on the same frequency at the same time, and tag interference, two or more readers attempting to communicate with a particular RFID tag at the same time. All reader interference caused by the operation of an RFID reader is referred to as a reader collision. Reader collisions prevent the colliding readers from communicating with all of the tags in their respective reading zones; therefore, collisions must be avoided to ensure proper and timely communication with all tags. We define the reader collision problem and present several graph coloring formulations for variants of the problem.
Maurizio Rebaudengo - One of the best experts on this subject based on the ideXlab platform.
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probabilistic dcs an rfid reader to reader anti collision protocol
Journal of Network and Computer Applications, 2011Co-Authors: Filippo Gandino, Renato Ferrero, Bartolomeo Montrucchio, Maurizio RebaudengoAbstract:The wide adoption of radio frequency identification (RFID) for applications requiring a large number of tags and readers makes critical the reader-to-reader collision problem. Various anti-collision protocols have been proposed, but the majority require considerable additional resources and costs. Distributed color system (DCS) is a state-of-the-art protocol based on time division, without noteworthy additional requirements. This paper presents the probabilistic DCS (PDCS) reader-to-reader anti-collision protocol which employs probabilistic collision resolution. Differently from previous time division protocols, PDCS allows multichannel transmissions, according to international RFID regulations. A theoretical analysis is provided in order to clearly identify the behavior of the additional parameter representing the probability. The proposed protocol maintains the features of DCS, achieving more efficiency. Theoretical analysis demonstrates that the number of reader-to-reader collisions after a slot change is decreased by over 30%. The simulation analysis validates the theoretical results, and shows that PDCS reaches better performance than state-of-the-art reader-to-reader anti-collision protocols.
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introducing probability in rfid reader to reader anti collision
Network Computing and Applications, 2009Co-Authors: Filippo Gandino, Renato Ferrero, Bartolomeo Montrucchio, Maurizio RebaudengoAbstract:Nowadays, several kinds of applications based on Radio Frequency Identification (RFID) employ a large number of tags and readers, involving collision problems. A relevant group of reader-to-reader anti-collision protocols are based on time division. Normally these protocols do not require special readers or additional entities; their main challenge is the collision resolution, since after a collision, readers have to choose a new time slot trying to avoid new collisions.It is observed that after a collision, its slot is often unoccupied, therefore this paper proposes to introduce the slot change probability as an additional parameter, in order to reduce the number of readers that change slot and the number of colliding transmissions. A new version of Distributed Color Selection (DCS) is presented, analyzed and compared with well-known protocols based on time division. The simulation analysis shows that the average time required to transmit may be reduced by over 10%.
