Editing Incidental imaging finding (section)

== Kidney ==
[[File:Contrast-enhanced ultrasonography of benign lesion.jpg|thumb|Unspecific cortical lesion on [[CT scan]] is confirmed cystic and benign with [[contrast-enhanced ultrasound|contrast-enhanced]] [[renal ultrasonography]].]]
Most [[renal cell carcinoma]]s are now found incidentally.<ref name="pmid11343669">{{cite journal |vauthors=Reddan DN, Raj GV, Polascik TJ |title=Management of small renal tumors: an overview |journal=Am. J. Med. |volume=110 |issue=7 |pages=558–62 |year=2001 |pmid=11343669 |doi=10.1016/S0002-9343(01)00650-7 }}</ref> Tumors less than 3&nbsp;cm in diameter less frequently have aggressive [[histology]].<ref name="pmid16890647">{{cite journal  |vauthors=Remzi M, Ozsoy M, Klingler HC, etal |title=Are small renal tumors harmless? Analysis of histopathological features according to tumors 4 cm or less in diameter |journal=J. Urol. |volume=176 |issue=3 |pages=896–9 |year=2006 |pmid=16890647 |doi=10.1016/j.juro.2006.04.047}}</ref>

A [[CT scan]] is the first choice modality for workup of solid masses in the kidneys. Nevertheless, hemorrhagic cysts can resemble renal cell carcinomas on CT, but they are easily distinguished with [[Doppler ultrasonography]] (Doppler US). In renal cell carcinomas, Doppler US often shows vessels with high velocities caused by neovascularization and arteriovenous shunting. Some renal cell carcinomas are hypovascular and not distinguishable with Doppler US. Therefore, renal tumors without a Doppler signal, which are not obvious simple cysts on US and CT, should be further investigated with [[contrast-enhanced ultrasound]], as this is more sensitive than both Doppler US and CT for the detection of hypovascular tumors.<ref name=Hansen2015>Content initially copied from: {{cite journal|last1=Hansen|first1=Kristoffer|last2=Nielsen|first2=Michael|last3=Ewertsen|first3=Caroline|title=Ultrasonography of the Kidney: A Pictorial Review|journal=Diagnostics|volume=6|issue=1|year=2015|pages=2|issn=2075-4418|doi=10.3390/diagnostics6010002|pmid=26838799|pmc=4808817|doi-access=free}} [https://creativecommons.org/licenses/by/4.0/ (CC-BY 4.0)]</ref>