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2. Baseline Predictors Of Knee Cartilage Magnetic Resonance T1ρ And T2 Relaxation Times 10 Years After Anterior Cruciate Ligament Reconstruction

Author

Holden, W., primary, Lartey, R., additional, Obuchowski, N., additional, Gaj, S., additional, Kim, J., additional, Li, M., additional, Eck, B.L., additional, Winalski, C.S., additional, Altahawi, F., additional, Jones, M.H., additional, Huston, L.J., additional, Harkins, K.D., additional, Knopp, M.V., additional, Kaeding, C.C., additional, Spindler, K.P., additional, and Li, X., additional

Published
2023
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4. Radiomics Features Of Infrapatellar Fat Pad Are Associated With Symptomatic And Radiographic Post-Traumatic Osteoarthritis At 10+ Years After Acl Reconstruction

Author

Khan, S., primary, Lartey, R., additional, Obuchowski, N., additional, Gaj, S., additional, Kim, J., additional, Li, M., additional, Eck, B., additional, Winalski, C.S., additional, Altahawi, F., additional, Jones, M.H., additional, Huston, L.J., additional, Harkins, K.D., additional, Knopp, M.V., additional, Kaeding, C.C., additional, Spindler, K.P., additional, and Li, X., additional

Published
2023
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6. Reproducibility of T1ρ and T2 quantification in a multi-vendor multi-site study

Author

Lartey, R., primary, Nanavati, A., additional, Kim, J., additional, Li, M., additional, Xu, K., additional, Nakamura, K., additional, Shin, W., additional, Winalski, C.S., additional, Obuchowski, N., additional, Bahroos, E., additional, Link, T.M., additional, Hardy, P.A., additional, Peng, Q., additional, Liu, K., additional, Fung, M., additional, Wu, C., additional, and Li, X., additional

Published
2023
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7. P15.11.A 18F-Fluciclovine PET/CT to distinguish radiation necrosis from tumour progression in brain metastases treated with stereotactic radiosurgery: results of a prospective pilot study

Author

Tom, M C, primary, DiFilippo, F, additional, Smile, T, additional, Jones, S E, additional, Suh, J H, additional, Murphy, E S, additional, Yu, J S, additional, Mohammadi, A M, additional, Barnett, G H, additional, Angelov, L, additional, Huang, S S, additional, Wu, G, additional, Johnson, S, additional, Obuchowski, N, additional, Ahluwalia, M, additional, Peereboom, D, additional, Stevens, G, additional, and Chao, S, additional

Published
2022
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9. Reproducibility of T1ρ and T2 quantification in a multi-vendor multi-site study.

Author

Lartey, R., Nanavati, A., Kim, J., Li, M., Xu, K., Nakamura, K., Shin, W., Winalski, C.S., Obuchowski, N., Bahroos, E., Link, T.M., Hardy, P.A., Peng, Q., Liu, K., Fung, M., Wu, C., Li, X., Lartey, Richard, Nanavati, Andreas, and Kim, Jeehun

Abstract

Objective: To evaluate the multi-vendor multi-site reproducibility of two-dimensional (2D) multi-echo spin-echo (MESE) T2 mapping (product sequences); and to evaluate the longitudinal reproducibility of three-dimensional (3D) magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (MAPSS) T1ρ and T2 mapping (research sequences), and 2D MESE T2 mapping, separated by 6 months, in a multi-vendor multi-site setting.Methods: Phantoms and volunteers (n = 5 from each site, n = 20 in total) were scanned on four 3 T magnetic resonance (MR) systems from four sites and three vendors (Siemens, General Electric, and Phillips). Two traveling volunteers (3 knees) scanned at all 4 sites at baseline and 6-month follow-up. Data was transferred to one site for centralized processing. Coefficients of variation (CVs) were calculated to evaluate reproducibility.Results: For baseline 2D MESE T2 measures, average CV were 0.37-2.45% (intra-site) and 5.96% (inter-site) for phantoms, and 3.15-8.49% (intra-site) and 14.16% (inter-site) for volunteers. For longitudinal phantom data, intra-site CVs were 1.42-3.48% for 3D MAPSS T1ρ, 1.77-3.56% for 3D MAPSS T2, and 1.02-2.54% for 2D MESE T2. For the longitudinal volunteer data, the intra-site CVs were 2.60-4.86% for 3D MAPSS T1ρ, 3.33-7.25% for 3D MAPSS T2, and 3.11-8.77% for 2D MESE T2.Conclusion: This study demonstrated excellent intra-site reproducibility of 2D MESE T2 imaging, while its inter-site variation was slightly higher than 3D MAPSS T2 imaging (10.06% as previously reported). This study also showed excellent reproducibility of longitudinal T1ρ and T2 cartilage quantification, in a multi-vendor multi-site setting for both product 2D MESE T2 and 3D MAPSS T1p/T2 research sequences. [ABSTRACT FROM AUTHOR]

Published
2023
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10. 18F-Fluciclovine PET/CT to Distinguish Radiation Necrosis From Tumor Progression in Brain Metastases Treated With Stereotactic Radiosurgery: Results of a Prospective Pilot Study

Author

Tom, M.C., primary, DiFilippo, F., additional, Smile, T., additional, Jones, S.E., additional, Suh, J.H., additional, Murphy, E.S., additional, Yu, J.S., additional, Mohammadi, A.M., additional, Barnett, G.H., additional, Angelov, L., additional, Huang, S.S., additional, Wu, G., additional, Johnson, S., additional, Obuchowski, N., additional, Ahluwalia, M., additional, Peereboom, D., additional, Stevens, G., additional, and Chao, S.T., additional

Published
2021
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11. Incorporating radiomics into clinical trials: expert consensus on considerations for data-driven compared to biologically driven quantitative biomarkers

Author

Fournier, L. (Laure), Costaridou, L. (Lena), Bidaut, L. (Luc), Michoux, N. (Nicolas), Lecouvet, F.E. (Frédéric), de Geus-Oei, L.-F. (Lioe-Fee), Boellaard, R. (Ronald), Oprea-Lager, D.E. (Daniela E.), Obuchowski, N. (Nancy), Caroli, A. (Anna), Kunz, W.G. (Wolfgang), Oei, E.H.G. (Edwin), O’Connor, J.P.B. (James P. B.), Mayerhoefer, M.E. (Marius E.), Franca, M. (Manuela), Alberich-Bayarri, A. (Angel), Deroose, C.M. (Christophe M.), Loewe, C. (Christian), Manniesing, R. (Rashindra), Caramella, C. (Caroline), Lopci, E. (Egesta), Lassau, N. (Nathalie), Persson, A. (Anders), Achten, R. (Rik), Rosendahl, K. (Karen), Clement, O. (Olivier), Kotter, E. (Elmar), Golay, A. (Alain), Smits, M. (Marion), Dewey, T.M. (Todd M.), Sullivan, D.C. (Daniel C.), Lugt, A. (Aad) van der, DeSouza, N.M. (Nandita M.), Fournier, L. (Laure), Costaridou, L. (Lena), Bidaut, L. (Luc), Michoux, N. (Nicolas), Lecouvet, F.E. (Frédéric), de Geus-Oei, L.-F. (Lioe-Fee), Boellaard, R. (Ronald), Oprea-Lager, D.E. (Daniela E.), Obuchowski, N. (Nancy), Caroli, A. (Anna), Kunz, W.G. (Wolfgang), Oei, E.H.G. (Edwin), O’Connor, J.P.B. (James P. B.), Mayerhoefer, M.E. (Marius E.), Franca, M. (Manuela), Alberich-Bayarri, A. (Angel), Deroose, C.M. (Christophe M.), Loewe, C. (Christian), Manniesing, R. (Rashindra), Caramella, C. (Caroline), Lopci, E. (Egesta), Lassau, N. (Nathalie), Persson, A. (Anders), Achten, R. (Rik), Rosendahl, K. (Karen), Clement, O. (Olivier), Kotter, E. (Elmar), Golay, A. (Alain), Smits, M. (Marion), Dewey, T.M. (Todd M.), Sullivan, D.C. (Daniel C.), Lugt, A. (Aad) van der, and DeSouza, N.M. (Nandita M.)

Abstract

Existing quantitative imaging biomarkers (QIBs) are associated with known biological tissue characteristics and follow a well-understood path of technical, biological and clinical validation before incorporation into clinical trials. In radiomics, novel data-driven processes extract numerous visually imperceptible statistical features from the imaging data with no a priori assumptions on their correlation with biological processes. The selection of relevant features (radiomic signature) and incorporation into clinical trials therefore requires additional considerations to ensure meaningful imaging endpoints. Also, the number of radiomic features tested means that power calculations would result in sample sizes impossible to achieve within clinical trials. This article examines how the process of standardising and validating data-driven imaging biomarkers differs from those based on biological associations. Radiomic signatures are best developed initially on datasets that represent diversity of acquisition protocols as well as diversity of disease and of normal findings, rather than within clinical trials with standardised and optimised protocols as this would risk the selection of radiomic features being linked to the imaging process rather than the pathology. Normalisation through discretisation and feature harmonisation are essential pre-processing steps. Biological correlation may be performed after the technical and clinical validity of a radiomic signature is established, but is not mandatory. Feature selection may be part of discovery within a radiomics-specific trial or represent exploratory endpoints within an established trial; a previously validated radiomic signature may even be used as a primary/secondary endpoint, particularly if associations are demonstrated with specific biological processes and pathways being targeted within clinical trials. Key Points: • Data-driven processes like radiomics risk false discoveries due to high-dimensionality

Published
2021
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12. Novel Approach to Risk Stratification in Left Ventricular Non-Compaction Using A Combined Cardiac Imaging and Plasma Biomarker Approach

Author

Ramchand, J, Podugu, P, Obuchowski, N, Harb, SC, Chetrit, M, Milinovich, A, Griffin, B, Burrell, LM, Tang, WHW, Kwon, DH, Flamm, SD, Ramchand, J, Podugu, P, Obuchowski, N, Harb, SC, Chetrit, M, Milinovich, A, Griffin, B, Burrell, LM, Tang, WHW, Kwon, DH, and Flamm, SD

Abstract

Background Left ventricular non-compaction remains a poorly described entity, which has led to challenges of overdiagnosis. We aimed to evaluate if the presence of a thin compacted myocardial layer portends poorer outcomes in individuals meeting cardiac magnetic resonance criteria for left ventricular non-compaction . Methods and Results This was an observational, retrospective cohort study involving individuals selected from the Cleveland Clinic Foundation cardiac magnetic resonance database (N=26 531). Between 2000 and 2018, 328 individuals ≥12 years, with left ventricular non-compaction or excessive trabeculations based on the cardiac magnetic resonance Petersen criteria were included. The cohort comprised 42% women, mean age 43 years. We assessed the predictive ability of myocardial thinning for the primary composite end point of major adverse cardiac events (composite of all-cause mortality, heart failure hospitalization, left ventricular assist device implantation/heart transplant, ventricular tachycardia, or ischemic stroke). At mean follow-up of 3.1 years, major adverse cardiac events occurred in 102 (31%) patients. After adjusting for comorbidities, the risk of major adverse cardiac events was nearly doubled in the presence of significant compacted myocardial thinning (hazard ratio [HR], 1.88 [95% CI, 1.18‒3.00]; P=0.016), tripled in the presence of elevated plasma B-type natriuretic peptide (HR, 3.29 [95% CI, 1.52‒7.11]; P=0.006), and increased by 5% for every 10-unit increase in left ventricular end-systolic volume (HR, 1.01 [95% CI, 1.00‒1.01]; P=0.041). Conclusions The risk of adverse clinical events is increased in the presence of significant compacted myocardial thinning, an elevated B-type natriuretic peptide or increased left ventricular dimensions. The combination of these markers may enhance risk assessment to minimize left ventricular non-compaction overdiagnosis whilst facilitating appropriate diagnoses in those with true disease.

Published
2021

16. Longitudinal reproducibility of T1ρ and T2 quantification in a multi-vendor multi-site study

Author

Lartey, R., primary, Nanavati, A., additional, Kim, J., additional, Li, M., additional, Nakamura, K., additional, Shin, W., additional, Winalski, C.S., additional, Obuchowski, N., additional, Tanaka, M., additional, Bahroos, E., additional, Link, T.M., additional, Hardy, P.A., additional, Peng, Q., additional, Liu, K., additional, Fung, M., additional, Wu, C., additional, and Li, X., additional

Published
2021
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18. 18F-Fluciclovine PET/CT to Distinguish Radiation Necrosis from Tumor Progression in Brain Metastases Treated with Stereotactic Radiosurgery

Author

Tom, M.C., primary, DiFilippo, F., additional, Jones, S.E., additional, Suh, J.H., additional, Murphy, E.S., additional, Yu, J.S., additional, Mohammadi, A.M., additional, Barnett, G.H., additional, Angelov, L., additional, Huang, S.S., additional, Wu, G., additional, Obuchowski, N., additional, Ahluwalia, M., additional, Peereboom, D., additional, Stevens, G., additional, and Chao, S.T., additional

Published
2020
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25. Multi-vendor multi-site T1ρ and T2 quantification of knee cartilage.

Author

Kim, J., Mamoto, K., Lartey, R., Xu, K., Nakamura, K., Shin, W., Winalski, C.S., Obuchowski, N., Tanaka, M., Bahroos, E., Link, T.M., Hardy, P.A., Peng, Q., Reddy, R., Botto-van Bemden, A., Liu, K., Peters, R.D., Wu, C., and Li, X.

Abstract

Objective: To develop 3D T1ρ and T2 imaging based on the same sequence structure on MR systems from multiple vendors, and to evaluate intra-site repeatability and inter-site inter-vendor reproducibility of T1ρ and T2 measurements of knee cartilage.Methods: 3D magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (3D MAPSS) were implemented on MR systems from Siemens, GE and Philips. Phantom and human subject data were collected at four sites using 3T MR systems from the three vendors with harmonized protocols. Phantom data were collected by means of different positioning of the coil. Volunteers were scanned and rescanned after repositioning. Two traveling volunteers were scanned at all sites. Data were transferred to one site for centralized processing.Results: Intra-site average coefficient of variations (CVs) ranged from 1.09% to 3.05% for T1ρ and 1.78-3.30% for T2 in phantoms, and 1.60-3.93% for T1ρ and 1.44-4.08% for T2 in volunteers. Inter-site average CVs were 5.23% and 6.45% for MAPSS T1ρ and T2, respectively in phantoms, and 8.14% and 10.06% for MAPSS T1ρ and T2, respectively, In volunteers.Conclusion: This study showed promising results of multi-site, multi-vendor reproducibility of T1ρ and T2 values in knee cartilage. These quantitative measures may be applied in large-scale multi-site, multi-vendor trials with controlled sequence structure and scan parameters and centralized data processing. [ABSTRACT FROM AUTHOR]

Published
2020
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26. STARD for Abstracts : Essential items for reporting diagnostic accuracy studies in journal or conference abstracts

Author

Cohen, Jf, Korevaar, Da, Gatsonis, Ca, Glasziou, Pp, Hooft, L, Moher, D, Reitsma, Jb, de Vet HC, Bossuyt, Pm, STARD Group: Alonzo, T, Altman, Dg, Azuara-Blanco, A, Bachmann, L, Blume, J, Boutron, I, Bruns, D, Büller, H, Buntinx, F, Byron, S, Chang, S, Cohen, J, Cooper, R, de Groot, J, de Vet HCW, Deeks, J, Dendukuri, N, Dinnes, J, Fleming, K, Glasziou, Pg, Golub, Rm, Guyatt, G, Heneghan, C, Hilden, J, Horvath, R, Hunink, M, Hyde, C, Ioannidis, J, Irwig, L, Janes, H, Kleijnen, J, Knottnerus, A, Kressel, Hy, Lange, S, Leeflang, M, Lijmer, Jg, Lord, S, Lumbreras, B, Macaskill, P, Magid, E, Mallett, S, Mcinnes, M, Mcneil, B, Mcqueen, M, Moons, K, Morris, K, Mustafa, R, Obuchowski, N, Ochodo, E, Onderdonk, A, Overbeke, J, Pai, N, Peeling, R, Pepe, M, Petersen, S, Price, C, Ravaud, P, Rennie, D, Rifai, N, Rutjes, A, Schunemann, H, Simel, D, Simera, I, Smidt, N, Steyerberg, E, Straus, S, Summerskill, W, Takwoingi, Y, Thompson, M, van den Bruel, A, van Maanen, H, Vickers, A, Virgili, G, Walter, S, Weber, W, Westwood, M, Whiting, P, Wilczynski, N, Ziegler, A., Epidemiology and Data Science, APH - Methodology, Epidemiology, Radiology & Nuclear Medicine, Erasmus MC other, Erasmus School of Health Policy & Management, Public Health, APH - Personalized Medicine, and Other departments

Subjects
Medicine(all), medicine.medical_specialty, Information retrieval, business.industry, MEDLINE, Diagnostic accuracy, General Medicine, Executive committee, 030218 nuclear medicine & medical imaging, 03 medical and health sciences, 0302 clinical medicine, Completion rate, Medicine, Medical physics, 030212 general & internal medicine, business, Web based survey
Abstract

Many abstracts of diagnostic accuracy studies are currently insufficiently informative. We extended the STARD (Standards for Reporting Diagnostic Accuracy) statement by developing a list of essential items that authors should consider when reporting diagnostic accuracy studies in journal or conference abstracts. After a literature review of published guidance for reporting biomedical studies, we identified 39 items potentially relevant to report in an abstract. We then selected essential items through a two round web based survey among the 85 members of the STARD Group, followed by discussions within an executive committee. Seventy three STARD Group members responded (86%), with 100% completion rate. STARD for Abstracts is a list of 11 quintessential items, to be reported in every abstract of a diagnostic accuracy study. We provide examples of complete reporting, and developed template text for writing informative abstracts.

Published
2017

30. STARD 2015 : an updated list of essential items for reporting diagnostic accuracy studies

Author

Bossuyt, Pm, Reitsma, Jb, Bruns, De, Gatsonis, Ca, Glasziou, Pp, Irwig, L, Lijmer, Jg, Moher, D, Rennie, D, de Vet HCW, Kressel, Hy, Rifai, N, Golub, Rm, Altman, Dg, Hooft, L, Korevaar, Da, Cohen JF [Contributors: Alonzo, T, Azuara-Blanco, A, Bachmann, L, Blume, J, Boutron, I, Bruns, D, Büller, H, Buntinx, F, Byron, S, Chang, S, Cohen, Jf, Cooper, R, de Groot, J, Deeks, J, Dendukuri, N, Dinnes, J, Fleming, K, Guyatt, G, Heneghan, C, Hilden, J, Horvath, R, Hunink, M, Hyde, C, Ioannidis, J, Janes, H, Kleijnen, J, Knottnerus, A, Lange, S, Leeflang, M, Lord, S, Lumbreras, B, Macaskill, P, Magid, E, Mallett, S, Mcinnes, M, Mcneil, B, Mcqueen, M, Moons, K, Morris, K, Mustafa, R, Obuchowski, N, Ochodo, E, Onderdonk, A, Overbeke, J, Pai, N, Peeling, R, Pepe, M, Petersen, S, Price, C, Ravaud, P, Rutjes, A, Schunemann, H, Simel, D, Simera, I, Smidt, N, Steyerberg, E, Straus, S, Summerskill, W, Takwoingi, Y, Thompson, M, van de Bruel, A, van Maanen, H, Vickers, A, Virgili, G, Walter, S, Weber, W, Westwood, M, Whiting, P, Wilczynski, N, Ziegler, A, APH - Amsterdam Public Health, 10 Public Health & Methodologie, Other departments, Epidemiology and Data Science, ACS - Amsterdam Cardiovascular Sciences, Vascular Medicine, and EMGO - Musculoskeletal health

Subjects
Quality Control, Research design, PRIMARY OUTCOMES, medicine.medical_specialty, Computer science, RANDOMIZED CONTROLLED-TRIALS, Clinical Biochemistry, MEDLINE, Diagnostic accuracy, Disclosure, GUIDELINES, Research Support, Data accuracy, Terminology as Topic, Journal Article, Humans, Research Methods & Reporting, Medicine, Radiology, Nuclear Medicine and imaging, Medical physics, Non-U.S. Gov't, Reference standards, Diagnostic Techniques and Procedures, Bias (Epidemiology), UTILITY, Diagnostic Tests, Routine, Information Dissemination, business.industry, STATEMENT, Research Support, Non-U.S. Gov't, Biochemistry (medical), Reproducibility of Results, Diagnostic test, General Medicine, Reference Standards, Data Accuracy, TRANSPARENT, Critical appraisal, EQUATOR, BIAS, Research Design, Practice Guidelines as Topic, TESTS, business
Abstract

Incomplete reporting has been identified as a major source of avoidable waste in biomedical research. Essential information is often not provided in study reports, impeding the identification, critical appraisal, and replication of studies. To improve the quality of reporting of diagnostic accuracy studies, the Standards for Reporting of Diagnostic Accuracy Studies (STARD) statement was developed. Here we present STARD 2015, an updated list of 30 essential items that should be included in every report of a diagnostic accuracy study. This update incorporates recent evidence about sources of bias and variability in diagnostic accuracy and is intended to facilitate the use of STARD. As such, STARD 2015 may help to improve completeness and transparency in reporting of diagnostic accuracy studies.

Published
2015

31. Yttrium-90 radioembolization versus doxorubicin-eluting beads chemoembolization in patients with infiltrative hepatocellular carcinoma: single center comparison of survival and toxicity

Author

Alian, A., primary, McLennan, G., additional, Bennett, S., additional, Kapoor, B., additional, Gill, A., additional, Levitin, A., additional, Sands, M., additional, Obuchowski, N., additional, Aucejo, F., additional, Menon, K., additional, Estfan, B., additional, Pillai, A., additional, and Kalva, S., additional

Published
2016
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33. Primary Cells Isolated from Human Knee Cartilage Reveal Decreased Prevalence of Progenitor Cells but Comparable Biological Potential During Osteoarthritic Disease Progression.

Author

Mantripragada, V. P., Bova, W. A., Boehm, C., Piuzzi, N. S., Obuchowski, N. A., Midura, R. J., and Muschler, G. F.

Subjects
OSTEOARTHRITIS, DISEASE progression, CARTILAGE, PROGENITOR cells, CELLULAR therapy
Abstract

Background: Current decisions on cellular therapies for osteoarthritis are based primarily on clinical experience or on assumptions about preferred cell sourcing. They have not been informed by rigorous standardized measurements of the chondrogenic connective-tissue progenitors (CTP-Cs) or their intrinsic diversity of chondrogenic potential. The goal of this study was to quantitatively define the CTP-Cs resident in cartilage of different grades of osteoarthritis and to compare their concentration, prevalence, and biological potential.Methods: Twenty-three patients who had varus malalignment of the knee and were scheduled to undergo elective total knee arthroplasty for idiopathic osteoarthritis and who had grade 1-2 osteoarthritis on the lateral femoral condyle and grade 3-4 osteoarthritis on the medial femoral condyle were recruited for study of the cartilage removed during surgery. CTP-Cs were assayed by a standardized colony-forming-unit assay using automated image-analysis software based on ASTM standard test method F2944-12.Results: Cell concentration was significantly greater (p < 0.001) in grade 3-4 cartilage than in grade 1-2 cartilage. The prevalence of CTP-Cs varied widely, but it trended lower in grade 3-4 cartilage than in grade 1-2 samples (p = 0.078). The biological performance of CTP-Cs from grade 1-2 and grade 3-4 cartilage was comparable. Increased cell concentration was a significant predictor of decreased CTP-C prevalence (p = 0.002).Conclusions: Although grade 3-4 cartilage showed fewer CTP-Cs than grade 1-2 cartilage, the range of biological performance was comparable, which suggests that either may be used as a source for potent CTP-Cs. However, the biological reason for the heterogeneity of CTP-Cs in cartilage and the biological implications of that heterogeneity are not well understood and require further study.Clinical Relevance: In order to improve the efficacy of cartilage cell therapy procedures, it is key to characterize the quality and quantity of the cells and progenitors being administered. Additionally, understanding the heterogeneity in order to select appropriate subsets of populations will improve the rigor of decisions concerning cell sourcing and targeting for pharmacological and cellular therapies. [ABSTRACT FROM AUTHOR]

Published
2018
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39. Assessing the performance of prediction models: A framework for traditional and novel measures

Author

Steyerberg, E.W. (Ewout), Vickers, A.J. (Andrew), Cook, N.R. (Nancy), Gerds, T.A. (Thomas), Gonen, M. (Mithat), Obuchowski, N. (Nancy), Pencina, M. (Michael), Kattan, M.W. (Michael), Steyerberg, E.W. (Ewout), Vickers, A.J. (Andrew), Cook, N.R. (Nancy), Gerds, T.A. (Thomas), Gonen, M. (Mithat), Obuchowski, N. (Nancy), Pencina, M. (Michael), and Kattan, M.W. (Michael)

Abstract

The performance of prediction models can be assessed using a variety of methods and metrics. Traditional measures for binary and survival outcomes include the Brier score to indicate overall model performance, the concordance (or c) statistic for discriminative ability (or area under the receiver operating characteristic [ROC] curve), and goodness-of-fit statistics for calibration.Several new measures have recently been proposed that can be seen as refinements of discrimination measures, including variants of the c statistic for survival, reclassification tables, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Moreover, decision-analytic measures have been proposed, including decision curves to plot the net benefit achieved by making decisions based on model predictions.We aimed to define the role of these relatively novel approaches in the evaluation of the performance of prediction models. For illustration, we present a case study of predicting the presence of residual tumor versus benign tissue in patients with testicular cancer (n = 544 for model development, n = 273 for external validation).We suggest that reporting discrimination and calibration will always be important for a prediction model. Decision-analytic measures should be reported if the predictive model is to be used for clinical decisions. Other measures of performance may be warranted in specific applications, such as reclassification metrics to gain insight into the value of adding a novel predictor to an established model.

Published
2010
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48. Lumbar degenerative disk disease: prospective comparison of conventional T2-weighted spin-echo imaging and T2-weighted rapid acquisition relaxation-enhanced imaging

Author

Ross, J S, Ruggieri, P, Tkach, J, Obuchowski, N, Dillinger, J, Masaryk, T J, and Modic, M T

Subjects
Spinal Stenosis, Humans, Comparative Study, Spinal Diseases, Prospective Studies, Spondylolisthesis, Artifacts, Intervertebral Disc, Magnetic Resonance Imaging, Intervertebral Disc Displacement
Abstract

PURPOSE: To compare conventional T2-weighted spin-echo imaging with a rapid acquisition relaxation enhanced (RARE) technique in the routine evaluation of lumbar degenerative disk disease. METHODS: Thirty consecutive patients referred for evaluation of the lumbar spine for suspected degenerative disk disease were evaluated with sagittal and axial T1-weighted spin-echo, conventional T2-weighted spin-echo, and T2-weighted RARE "turbo spin-echo" sequences (4000/93/2 (repetition time/echo time/excitations), 192 x 256, echo train length of 8). Conventional T2-weighted and RARE images were evaluated independently by two neuroradiologists for image quality, presence of artifacts, cerebrospinal fluid signal intensity, extradural interface conspicuity, intradural nerve root conspicuity, soft-tissue detail, and signal intensity of normal and degenerated intervertebral disks. RESULTS: Both readers rated the cerebrospinal fluid signal higher, the extradural interface conspicuity higher, and the nerve root detail greater on the turbo spin-echo than on conventional spin-echo images. Neither reader had a significant difference in ranking "normal" or "degenerated" disk signal on the two sequences. Both readers rated soft-tissue detail higher for conventional than for turbo spin-echo. CONCLUSION: RARE sequences can replace conventional T2-weighted spin-echo sagittal studies for degenerative lumbar disk disease.

Published
1993

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