This document discusses the use of contrast enhanced ultrasound (CEUS) to characterize renal cysts. It notes that CEUS can help differentiate between benign and malignant cysts by depicting the microcirculation and applying the Bosniak classification system. CEUS preserves renal function compared to CT and has no radiation risk. It is useful when CT is inconclusive, the patient has renal dysfunction or iodine allergy, or to avoid additional radiation exposure from repeat CT exams. The document provides details on the Bosniak classification applied to CEUS findings and examples of different classification categories. It emphasizes the importance of vascularity seen on CEUS for accurate cyst characterization.

1. CEUS ON RENAL CYSTS
Michail Papagiannakis
Radiology department SÄS 2013
CEUS=Contrast Enhanced UltraSound
A quite new promising method characterising
micro-circulation using micro bubbles
It can be used on anything ultrasound waves
can reach.(L.Thorelius,CEUS International
Course Hanover, 2008)
Spatial resolution :Ultrasound>MRI>CECT

2. Indications on kidneys
Plain ultrasound is the method of
choice for identifying simple
cysts (BOSNIAK I-II)(BOSNIAK,
UROLOGY,4/2005)(Quaia et al.,
AJR, 5/2008)
The method is insufficient when
the cysts seem complicated and
cannot differentiate the cysts that
need to be removed, since the
most sensitive part of Bosniak´s
classification is
vascularity.(Ascenti et al,
Radiology, 4/2007)

3. The gold standard for differentiating between benign and malignant
cysts is the K- K+ CT with the BOSNIAK classification applied.
However BOSNIAK classification can be used on other contrast
enhanced methods depicting vascularity (BOSNIAK,
UROLOGY,4/2005).Since the last update of the classification,
vascularity has been upgraded to the most important feature
differentiating between surgical cat. III and non surgical lesions
cat.IIF (BOSNIAK, UROLOGY,4/2005).The importance of thick
calcifications and nonenhancing septa has been downgraded.

4. BUT
Many cysts are incidentally found on ultrasound or NECT or on one
phase CECT
AND THEN….
The lesions need to be assessed with another method
or with CT urography
But if the patient has reduced renal function or iodine contrast allergy
Or is young and we don’t want to nuke him/her again.
Or we cant handle the demand for CT exams any longer
Or the the double or single phased CT was proven to be inconclusive
Then a method besides CECT is needed

5. WHEN CEUS is useful :
1) If we only need to check the kidneys, remember that on CEUS there is no excretory
phase. We can´t examine the ureters like in CECT.
2) When we need to depict and characterise a lesion´s microcirculation and then apply
the BOSNIAK classicification (Ascenti et al.,Radiology,8/2006. Quaia et al, AJR ,
10/2008.). CEUS helps not only in the characterization of complex cysts
detected on baseline US but also in the characterization of indeterminate
cystic lesions on CT or Magnetic Resonance (MR).(Nicolau et al.Abdominal
imaging,4/2011)
3) Preserve patient´s renal function because CEUS is not going to compromise it.
4) If there is known iodine OR gadolinium contrast allergy.The ultrasound contrast
agents used in Europe (sonovue) and Canada, USA(definity) are safer than the MR
and CT contrast agents(Piscaglia et al, Ultrasound in Med Biology,2006).Adverse
reactions to sonovue are not correlated with CT or MR contrast agents allergy.
5) Radiation and cost-effectiveness:
Ultrasound is a patient friendly, safe fast and cheap method with no radiation.The
amount of contrast that is necessary per patient makes CEUS actually cheaper
compared to CT and MRI.The total time to reach a diagnosis is less with CEUS, since
nowadays thinner slices are used on CT-MRI which means more pictures to go
through.

6. INCONCLUSIVE CT OR INCIDENTAL FINDINGS
CT
MRI K+ CEUS
THERE IS NO IMAGING PANAKEIA , DJ WILSON, MSC MRI COURSE,OXFORD 2010

7. Check our website if on any doubt
about indications.
http://intrasas.vgregion.se/sv/SIW/Organis
ation/Bild--och-laboratoriemedicin/Bild--
och-funktionsmedicin/Ultraljud/Riktlinjer-
UL/Kontrastforstarkt-ultraljud-CEUS/

8. Contraindications
1) Known reaction to sonovue. We had 2 (very mild)
they usually happen within 5 min.
2) Pulmonary hypertension.Very severe COL
3) Heart infarct during the last 3 months.
4) Instable angina pectoris.
5) Generally instable, critically ill patients.
6) Pregnancy and breast-feeding(that is a relative
contra-indication to be evaluated per case).
Sonovue doesn't seem to pass the placenta but
sonovue´s by-products were identified in breast
milk. Is radiation to the foetus a better option? Is
gadolinium safer for the foetus?

9. What to do when a request for
RENAL US-CEUS arrives?
1. Carefully examine the patient´s history
Is it a first time examination?
Is it only the kidneys-bladder to be examined?Or is there a need for a more
complete exam ?Check the symptoms and the reffering physicians
question´s (CT-urography) ?
The ability to use CEUS directly when performing a US is invaluable.
Incidental findings on US can be directly characterised more adequately
with the use of CEUS(Ingee et al.WJR, 1/2010)(Quaia et al., AJR, 5/2008).This
reduces the waiting lists the pressure to other modalities and relieves the patient ,
since it reduces the false positive and negative cases that baseline Us has.
Is there adequately trained personel to handle the case?A CEUS exam is
quite demanding .So it is vital to have a CEUS team and that everyone is
well trained.

10. 2. Is this a control of a known already
characterized lesion?
In that case we would have a Bosniak 2f cyst.These cysts are probably
benign but this need´s to be proven by follow-ups.
A 3-5 year observation period with 6 month intervals is necessary because
slow growing RCC´s exist.
The problem is that there is no consensus about the observation period.
Using baseline Us for some follow-ups is not a good option since it may
create false negative cases by not identifying any vascular changes or
create false positive cases because of artefacts etc.

11. Baseline US does not identify vascularity the most sensitive characteristic of
the BOSNIAK clasification
Same patient BOSNIAK 4, would u be certain on the B mode ?

12. 3. Is this an inconclusive case from CT or
MRI ?
Good cooperation with other modalities is vital and filtering the
cases where CEUS is NOT going to help is also important.
If baseline US exam is of low quality because of artefacts, gas or
patient habitus and lesions localisation then CEUS may not help.Big
calcifications?Forget CEUS.
Why other exams were inconclusive?US contrast agent is purely
intravascular and that is a main advantage compared with other
modalities.When you have high signal on CEUS you have
vessels.US and CEUS have a higher spatial resolution compared
with CT and MRI.
Even in difficult cases fusion imaging can increase your confidence
that you re at the right spot.Sometimes a lesion is difficult to see on
Us or an area with several lesions may be difficult to examine
without increasing the times you inject and spoiling the labs
programme.

13. When is CEUS useless
Never?
Contraindications
When a good baseline exam was
impossible.You can’t characterize things
you don’t see.
Patient needs to cooperate and be trained
You need to catch up with the bubbles

14. Technique
To do that you must have a good baseline technique, have the lesion in
plane just before the arrival of the bubbles and take good short video loops
during all phases(cortical and medulary phase).
Identify your target during baseline and choose an ideal plane to start
filming.
Think as a film director, it is vital to take representative video loops.It´s your
movie u can make it award winning or a junk movie!!!!!!!
Usually intermittent scanning of the lesion for 3 min is adequate.
Inject the right quantity.
If you are not happy with the videos you took inject again and start from
scratch.But don´t forget to destroy the bubbles first.
You need to be aware of the pitfalls of CEUS .
CEUS is performed like a good B mode ultrasound exam with one major
difference :
•You must catch up with the bubbles and not to destroy them.

15. How much to inject and how
Usually for the kidneys 1.2mL would be ok
There is no concensus on the quantity depends
on patients habitus etc
Always flush 10 mL saline after the injection.
If you are planning to scan the liver during
parenchymal phase use more contrast
You cannot scan both kidneys on all phases
during one injection
If you want to scan more than one lesion inject
twice even if you re scanning the same kidney.

16. Pitfalls
Missing the arrival of the
bubbles is sometimes
loosing half the exam
Destroying the bubbles
by using high MI is fatal,
you create a false
negative .
Destroying the bubbles
by scanning the lesion for
too long usually creates a
pseudo washout.
Saving a whole 3min
video loop is useless , too
many pictures to go
through later.And a
pseudo-washout to deal
with.
Using too much contrast
creates glare artefact or
very high signal intensity
and blocks your view.

17. REPORTING
Care should be taken that BOSNIAK method is based on CT , all the other
methods are having better spatial and contrast resolution so occasionally
discrepancies may appear and create difficulties on the patients
management.Since the most important feature of the Bosniak classification
is vascularity the higher spatial resolution of CEUS and the ability to depict
microcirculation should be considered when writing a report.
Vascularity is the most important feature but remember that CEUS identifies
even the tiniest capilaries so don´t mix the BOSNIAK 2 with the 2f or the 2f
with the 3.
Describe the lesion or lesions size,place,appearance on baseline and
CEUS and try to classify according to BOSNIAK .

18. Bosniak classification on CEUS
(Nicolau et al.Abdominal imaging,4/2011)
I 0% malignancy No echoes within the mass, and sharply marginated smooth
walls
No septa, calcifications or solid components
No enhancement after intravenous contrast agent injection
II 0% malignancy It may contain few hairline-thin septa, fine calcifications in a
short segment of the wall or slightly thickened calcification. It
may show minimal enhancement ‘‘just perceived’’ of the
septa without soft-tissue nodular enhancement
IIF 5% malignancy It may contain multiple hairline-thin septa, smooth minimal
thickening of the wall or septa and thick
or nodular calcifications. It may show minimal enhancement
‘‘just perceived’’ of the septa, but without soft-tissue nodular
enhancement
III 50-70% malignancy It may contain thickened irregular or smooth wall or septa
with measurable enhancement. No solid enhancing lesions
are present
IV 95-100% malignancy It may contain soft-tissue enhancing mass independent of
the wall or septa

19. EXAMPLES B I-II
B 1 = no vessels

20. EXAMPLE B IIF
Nicolau et al.

21. EXAMPLES B III
Nicolau et al.

22. EXAMPLES B IV
Nicolau et al

23. Literature
1) An update of the Bosniak renal cyst classification system.Israel GM, Bosniak MA.Urology. 2005
Sep;66(3):484-8. Review.
2) Contrast enhanced ultrasonography prediction of cystic renal mass in comparison to histopathology.Xu Y,
Zhang S, Wei X, Pan Y, Hao J.Clin Hemorheol Microcirc. 2013 Oct 28.
3) Renal complex cysts in adults: contrast-enhanced ultrasound.Nicolau C, Bunesch L, Sebastia C.Abdom
Imaging. 2011 Dec;36(6):742-52
4) Contrast enhanced ultrasound of renal masses.Ignee A, Straub B, Schuessler G, Dietrich CF.World J
Radiol. 2010 Jan 28;2(1):15-31.
5) Multislice computed tomography versus contrast-enhanced ultrasound in evaluation of complex cystic
renal masses using the Bosniak classification system.Clevert DA, Minaifar N, Weckbach S, Jung EM,
Stock K, Reiser M, Staehler M.Clin Hemorheol Microcirc. 2008;39(1-4):171-8.
6) Assessment of cystic renal masses based on Bosniak classification: comparison of CT and contrast-
enhanced US.
Park BK, Kim B, Kim SH, Ko K, Lee HM, Choi HY.Eur J Radiol. 2007 Feb;61(2):310-4. Epub 2006 Nov 13.
7) Evaluation of Bosniak category IIF complex renal cysts.Graumann O, Osther SS, Karstoft J, Hørlyck A,
Osther PJ.
Insights Imaging. 2013 Aug;4(4):471-80
8) Comparison of contrast-enhanced sonography with unenhanced sonography and contrast-enhanced CT
in the diagnosis of malignancy in complex cystic renal masses.Quaia E, Bertolotto M, Cioffi V, Rossi A,
Baratella E, Pizzolato R, Cov MA.AJR Am J Roentgenol. 2008 Oct;191(4):1239-49
9) Complex cystic renal masses: characterization with contrast-enhanced US.Ascenti G, Mazziotti S,
Zimbaro G, Settineri N, Magno C, Melloni D, Caruso R, Scribano E.Radiology. 2007 Apr;243(1):158-65.
10) Evaluating the perfusion of occupying lesions of kidney and bladder with contrast-enhanced
ultrasound.Wang XH, Wang YJ, Lei CG. Clin Imaging. 2011 Nov-Dec;35(6):447-51.
Dedicated to my first teacher in Radiology Giannis Papagiannakis (1939-2012)