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[Contrast-enhanced subtraction MRT in the spin-echo technic].

PURPOSE
The aim of the retrospective study was to determine whether subtraction of spin-echo images is useful for estimating intensity and extension of contrast enhancement when practised in daily routine diagnostic work.


METHODS
348 patients with different diseases of the musculoskeletal and neuro system were examined with MRI using a T1-weighted spin-echo sequence before and after application of 0.1 mmol/kg Gd-DTPA with subsequent subtraction of both measurements. Usefulness of the source images, pictorial quality of subtracted images and intensity of contrast enhancement were assessed subjectively.


RESULTS
Subtracted images were of sufficient quality in 85% of the cases, whereas source images were always usable except in 9 patients. It was easier to visualise the extent of contrast enhancement in subtracted than in non-subtracted images in examinations of the musculoskeletal system, whereas there was no difference in the neuro system. Contrast enhancement could definitely be excluded in 15% of the patients and was stated to be of low, medium and high intensity in 21%, 45% and 19%, respectively. In comparison with subtracted images lesions were stated to appear larger in 62% and 87%, smaller in 25% and 13%, and of the same size in 13% and 0% for T2-weighted and fat-suppressed images, respectively.


CONCLUSION
Subtraction of spin-echo images before and after application of contrast media is useful for estimating intensity and extension of contrast enhancement without essentially increasing time and costs of the examination. Extension of contrast enhancement in musculoskeletal lesions rarely correlates with the extension of signal changes in T2-weighted and fat-suppressed images.