Accuracy of radiography in grading and tissue-specific diagnosis : a study of 200 consecutive bone tumors of the hand

To determine the usefulness of radiography and magnetic resonance imaging in differentiating benign from malignant bony tumors of the hand and in making a tissue-specific diagnosis. Two hundred consecutive bony tumors of the hand, the details of which originated from a national databank, were studied in a prospective way by radiography (100%) and by MRI (25%). All tumors were graded on a five-point scale, from certainly benign to certainly malignant, using location and morphology as diagnostic parameters. For all tumors a tissue-specific diagnosis was made, by the proposal of three possibilities in decreasing order of probability. Histological diagnosis was made by peer review, according to the WHO classification. By the combining of "certainly" and "probably" benign (grades I and II) and "certainly" and "probably" malignant (grades IV and V), a correct grading was obtained in 165 (82.5%) of the cases (154 of the 173 benign and 11 of the 27 malignant tumors). A correct tissue-specific diagnosis was included in the three proposed differentials in 87.5%. MRI confirmed a correct diagnosis made on radiography in 72% and improved the grading capability by correctly upgrading malignant tumors and downgrading benign tumors in, respectively, 8% and 12%. The capability to obtain a tissue-specific diagnosis improved with change of an incorrect diagnosis on radiography to a correct one on MRI in 12 cases (24%). Subjective (semiquantitative) grading on radiography by an expert group proved to be excellent when compared with the results of a quantitative analysis of individual grading parameters. Multiple logistic regression analysis of these parameters resulted in a grading formula containing only six variables. The additional value of MRI in grading was amply demonstrated. Already high accuracy of radiography, in making a tissue-specific diagnosis, improved substantially after the performance of MRI.