...a space occupying lesion enhanced by the contrast medium...

See e.g.
"Computerized tomography (CT) demonstrated a greatly dilated
right lateral ventricle with no apparent space-occupying lesion within the ventricle and no passage of the contrast medium "
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&d...

"A 73-year-old woman with sudden onset headaches, balance problems, and one episode of syncope was diagnosed as having an irregular, contrast-enhancing, space-occupying lesion in..."
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&d...


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Note added at 25 mins (2004-07-26 10:13:44 GMT)
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\"Computed tomography of the neck with bolus contrast enhancement showed a space-occupying lesion which caused asymmetry of right pharyngeal valleculae.\"
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&d...

Also \"MASS\" or \"MASS LESION\", although \"space occupying lesion\" is used more often and is a more literal translation:

\"CT scans showed intracranial extradural contrast enhancing mass lesions in the anterior, middle or posterior cranial fossa...\"
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&d...