MR Imaging of lymph nodse

Metastases to local lymph nodes play a major role in tumour staging, choosing therapy and in predicting prognosis in patients with cancer. Histopathological examination of lymph nodes is regarded the gold standard for establishing nodal involvement, and is the final basis for therapeutic decisions. Although this method is an extremely valid diagnostic tool, it is invasive and thus bears a risk of complications, is time-consuming, and expensive. A non-invasive diagnostic tool is warranted. In this thesis we focus on two MR imaging techniques that are hypothesized to be able to increase diagnostic accuracy of MR lymph node staging. These two methods are diffusion weighted imaging (DWI) and contrast-enhanced MRI. Gadolinium-based contrast agents highlight tumour vascularity in organs and are widely used for primary tumour visualisation. We investigated the diagnostic accuracy of Gadolinium-enhanced MRI for staging lymph node metastases by means of a systematic review and meta-analysis. The meta-analysis showed that the weighted estimates of sensitivity and specificity of MRI in staging lymphatic metastases increased for the subgroup incorporating contrast enhancement in the malignancy criteria. The next three research questions being answered in this thesis are summarized using a clinical cohort including patients with gynaecological cancers in whom the pelvic lymph nodes were dissected for staging purposes. DWI added to conventional MR resulted in the additional detection of lymph nodes in all patients and these nodes were on average significant smaller than those detected by conventional MR (