Pelvimetrie mittels verschiedener kernspintomographischer Techniken vs. digitale Bildverstärkerradiographie: Genauigkeit, Zeitbedarf und Energiebelastung

Abstract

In 50 patients with suspected or proven cephalo-pelvine disproportion pelvimetry was performed with MR-tomography using a gradient-echo-sequence (FLASH 2D) before or after labour. Results were compared with measurements using digital radiography. In principle, both methods are exchangeable. The sagittal pelvic in- and outlet bispinous diameters are well reproducible. On the other hand, the transverse pelvic inlet and the distance between the ischiatic tubera are not so reliably reproduced. The accuracy of measurement does not depend on individual pelvic distances. Critical statistical analysis demonstrates, that in the worst case differences between the two methods might become unacceptable. Our results indicate two major reasons: 1. there are interobserver problems which cannot be neglected, and 2. the anatomical definition of referential landmarks for the measurements is unsafe. In 10 volunteers, a comparison was made between a T1-weighted spin-echo sequence (SE), a fast gradient echo sequence (FLASH-2D) and an ultrafast gradient echo technique (Turbo-FLASH). For the examination techniques presented here, the high-frequency exposure load or specific absorption rate (SAR loc and SAR total) is below the values permitted by the German Federal Health Bureau (Bundesgesundheitsamt). Whereas the exposure load in case of spin-echo takes (SE) is 22fold higher than with the gradient echo technique (GHE), the load values of ultra-fast GE (usGE) are only about 16% of the 2D-FLASH sequence or about 0.007% of SE. The difference in image quality does not affect the accuracy of measurement.