Comparison of PET/CT and Ultrasound in Staging of Malignant Melanoma

This is the first study which evaluates the different staging modalities 18F-2-fluoro-2-deoxy-D-glucose PET/CT (PET/CT) and diagnostic ultrasound (US) in a single patient cohort with malignant melanoma (MM). Previous analyses are ambivalent regarding the modality of choice. These analyses, however, compared separate patient cohorts for each modality.

Inclusion criteria were a primary staging or re-staging of suspected or confirmed MM with one or more PET/CT and/or one or more US. Exclusion criteria were the non-existence of a malignancy or a malignancy other than MM, alone or in combination with an MM.

The analysis includes the calculation of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy in a per-patient (PPA), per-examination (PEA) and per-lesion analysis (PLA). This was done individually for PET/CT and US, and in PLA also for the combination of these two radiological modalities. Furthermore, US was divided into US as a whole (wUS), peripheral lymph nodes (pUS) and/or abdomen (aUS).

The principle equivalence of the two imaging modalities is set up as a null hypothesis H0 in all three analyses. As a further null hypothesis H0, the equivalence of the combined application compared to the sole applications of the two imaging modalities is asserted. The aim is the refutation of the null hypothesis H0 by significant differences in sensitivity and specificity.