[Radiographic enlargement in the study of hand diseases. Digital versus conventional techniques]

The electronic magnification of digital images was compared with direct digital magnification and with plain radiograph magnification. A whole-body computed radiographic system with photostimulable phosphor plates contained inside standard X-ray cassettes was used. The small bones of the hands and wrists of 18 patients with traumatic (10 cases) or degenerative (8 cases) bone conditions mainly due to chronic renal failure were studied. Each patient was examined with all three techniques: the images were retrospectively reviewed by four observers relative to resolution, contrast, visibility of the lesions and diagnostic value of each method. The statistical analysis of our results demonstrated better yield of direct digital magnification than of plain radiograph (p = 0.00043) and of electronic (p = 7.5 10(-13) magnification. This finding was mainly due to density and contrast optimization of digital images, in spite of their low spatial resolution. This feature allows good simultaneous representation of structures with different radiographic densities, as it happens in the hand and wrist. Electronic magnification yielded less brilliant results, even if compared with plain radiographic studies (p = 0.0032). However, this limitation was compensated for by the fact that this technique is easier and quicker to perform and that it does not require any additional X-ray exposure.