HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Stapleton, S. J. Articles by Yaffe, M. J. Search for Related Content PubMed PubMed Citation Articles by Stapleton, S. J. Articles by Yaffe, M. J.

Determination of Thresholds for Detection of Cerebellar Blood Flow Deficits in Brain SPECT Images

Departments of Medical Biophysics, Radiology, and Medicine, University of Toronto, Sunnybrook Health Science Centre, Toronto, Canada

Correspondence: For correspondence and reprints contact: Dr. Martin J. Yaffe, PhD, Rm S113, Sunnybrook Health Science Centre, 2075 Bayview Ave., North York, Ontario, Canada M4N 3M5.

ABSTRACT

Two observer studies were performed to determine the threshold (i.e., ratio of the counts in a lesion area to the counts in the corresponding contralateral region) at which two experienced observers diagnosed blood flow deficits in the cerebellum in ^99mTc-HMPAO SPECT scans to be clinically significant, and investigate the effect of the intensity mapping scale on the detectability of lesions. Method: Lesions representing blood flow deficits varying from no decrease to a 12.5% decrease were simulated in 300 patient images. The first study, a receiver operator characteristics (ROC) experiment, used two observers to compare the detectability of lesions with three intensity mapping scales: two pseudocolor scales, and a linear gray scale. A second "threshold-criterion" study was done to estimate the threshold at which observers determine deficits to be clinically significant. Results: In the ROC study, the observers were more accurate in detecting lesions displayed in pseudocolor than in grayscale. In the threshold-criterion study, the threshold at which observers assessed clinically significant deficits was found to range between 0.900 and 0.950 (corresponding to a 5%–10% decrease in counts), depending on the observer, and the intensity mapping scale. For both observers, the detection threshold was higher (i.e., closer to 1.0) with the pseudocolor scale than with the gray scale. Conclusion: The definition of a threshold value for use in quantitative techniques is dependent on both the observer and the intensity mapping scale. Observers were more accurate with the pseudocolor scales.

Key Words: quantification • SPECT • ROC analysis

This article has been cited by other articles:

				L. O. Kapucu, A. Serdaroglu, C. Okuyaz, G. Kose, and K. Gucuyener Brain Single Photon Emission Computed Tomographic Evaluation of Patients With Childhood Absence Epilepsy J Child Neurol, August 1, 2003; 18(8): 542 - 548. [Abstract] [PDF]

				S. Vignola, F. Nobili, P. Picco, M. Gattorno, A. Buoncompagni, P. Vitali, G. Mariani, and G. Rodriguez Brain Perfusion SPECT in Juvenile Neuro-Behcet's Disease J. Nucl. Med., August 1, 2001; 42(8): 1151 - 1157. [Abstract] [Full Text] [PDF]