  We use coronal imaging observations with SDO/AIA, and Hinode/EIS spectral
data, to explore the potential of narrow band EUV imaging data for diagnosing
the presence of hot (T >~5MK) coronal plasma in active regions. We analyze
observations of two active regions (AR 11281, AR 11289) with simultaneous AIA
imaging, and EIS spectral data, including the CaXVII line (at 192.8A) which is
one of the few lines in the EIS spectral bands sensitive to hot coronal plasma
even outside flares. After careful coalignment of the imaging and spectral
data, we compare the morphology in a 3 color image combining the 171, 335, and
94A AIA spectral bands, with the image obtained for CaXVII emission from the
analysis of EIS spectra. We find that in the selected active regions the CaXVII
emission is strong only in very limited areas, showing striking similarities
with the features bright in the 94A (and 335A) AIA channels and weak in the
171A band. We conclude that AIA imaging observations of the solar corona can be
used to track hot plasma (6-8MK), and so to study its spatial variability and
temporal evolution at high spatial and temporal resolution.
