Radiology, Vol 178, 169-173, Copyright © 1991 by Radiological Society of North America
Mediastinal abnormalities: detection with storage phosphor digital radiography
CM Schaefer, R Greene, DA Hall, SR Lindemann, HJ Llewellyn, KA McCarthy, ER Pile- Spellman and JR Rubens
Department of Radiology I, Medizinische Hochschule Hannover, Federal Republic of Germany.
Conventional film radiography (FR) and six postprocessing algorithms of
isodose storage phosphor digital radiography (SR) (0.2-mm X 10-bit pixel
matrix) were compared in the evaluation of 40 mediastinal and 30 pulmonary
lesions in 60 patients who underwent computed tomography of the chest. The
six SR algorithms varied among each other in only one image parameter. One
algorithm approximated conventional image characteristics. The other five
algorithms were designed to optimize imaging of the mediastinum and tested
the effects of gray-scale reversal, adjustment of optical density, a linear
instead of a sigmoid gradation curve, and moderate edge enhancement of high
and medium spatial frequencies. Performance was evaluated by calculating
the average area under the receiver operating characteristic curve (Az) of
5,040 observations by six readers. Post-processing with high-frequency edge
enhancement and density optimization for the mediastinum significantly
improved performance of SR over FR in the detection of mediastinal lesions
(Az = .80 +/- .02 vs .73 +/- .01, respectively). Gray-scale reversal
significantly decreased performance (Az = .64 +/- .03). All SR algorithms
that were postprocessed to optimize imaging of the mediastinum were
significantly inferior to FR in the detection of pulmonary lesions.
