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Published online before print January 25, 2002, 10.1148/radiol.2223010413
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(Radiology 2002;222:722-728.)
© RSNA, 2002

Systemic Lupus Erythematosus: Diagnostic Application of Magnetization Transfer Ratio Histograms in Patients with Neuropsychiatric Symptoms—Initial Results1

Jamshid Dehmeshki, MSc, PhD, Mark A. Van Buchem, MD, PhD, Gerlof P. T. Bosma, MD, Tom W. J. Huizinga, MD, PhD and Paul S. Tofts, BA, DPhil

1 From the Institute of Neurology, University College London, England (J.D., P.S.T.); and Departments of Radiology (M.A.V.B., G.P.T.B.) and Rheumatology (T.W.J.H.), Leiden University Medical Center, the Netherlands. Received February 5, 2001; revision requested March 16; final revision received September 6; accepted September 19. Address correspondence to J.D., Medicsight plc, 46 Berkeley Square, London W1J 5AT, England (e-mail: j.dehmeshki@http-tech.com).



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Figure 1. Mean histograms for the active NPSLE (AC), control (CO), MS, past NPSLE (PN), and non-NPSLE (NON) disease groups. These histograms are normalized such that the total area under the histogram curve is fixed at unity.

 


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Figure 2. Scatterplots for the 10 binary classifications. The vertical axis shows the discriminant MDA score. Some groups, such as the active NPSLE () and control ({square}) groups, are well separated with no classification errors, whereas others, such as the past NPSLE ({bullet}) and MS ({triangleup}) groups, have considerable overlap and classification errors. {circ} = non-NPSLE group.

 


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Figure 3a. Scatterplots illustrate comparisons between the active NPSLE group () and the other groups, performed by using the following conventional parameters: (a) mean MTR, (b) MTR peak height, and (c) MTR peak location. In c, several samples have the same (integer) peak location value and thus coincide. {square} = control group, {triangleup} = MS group, {circ} = non-NPSLE group, {bullet} = past NPSLE group.

 


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Figure 3b. Scatterplots illustrate comparisons between the active NPSLE group () and the other groups, performed by using the following conventional parameters: (a) mean MTR, (b) MTR peak height, and (c) MTR peak location. In c, several samples have the same (integer) peak location value and thus coincide. {square} = control group, {triangleup} = MS group, {circ} = non-NPSLE group, {bullet} = past NPSLE group.

 


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Figure 3c. Scatterplots illustrate comparisons between the active NPSLE group () and the other groups, performed by using the following conventional parameters: (a) mean MTR, (b) MTR peak height, and (c) MTR peak location. In c, several samples have the same (integer) peak location value and thus coincide. {square} = control group, {triangleup} = MS group, {circ} = non-NPSLE group, {bullet} = past NPSLE group.

 


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Figure 4. Graph illustrates examples of binary classification. One sample is treated as an unknown subject for training with the remaining samples. On the left, in the binary differentiation between the active NPSLE group () and the control group ({square}), the unknown subject ({circ}), which in fact represents a patient with active NPSLE, has an MDA score that is far from zero (score, -7.54). Thus, we can be sure of the classification, and, indeed, the subject was correctly assigned to the active NPSLE group. In the middle, in the binary differentiation between the active NPSLE group and the past NPSLE group ({bullet}), the unknown subject, which in fact also represents a patient with active NPSLE (score, -1.41), has an MDA score that is nearer to the mean score of the active NPSLE group. This low score and the position in the region of overlap tell us that confidence in the classification was low. Nonetheless, the subject was correctly assigned. On the right, in the binary differentiation between the active NPSLE group and the past NPSLE group, the unknown subject, which in fact represents a patient with past NPSLE (score, -0.42), has an MDA score that is nearer to the mean score of the active NPSLE group. Confidence in the classification was low, however, and the subject was incorrectly assigned.

 





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