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Page 2 of 11 Cicero et al. Mini-invasive Surg 2019;3:25 I http://dx.doi.org/10.20517/2574-1225.2018.012

of cases are malignant tumors, they show a good natural history according to DISSRM Registry. Indeed,
SRMs growth rate and variability decrease with time during active surveillance: in patients of advanced
age or with serious comorbid conditions, SMRs can be managed conservatively with little change in overall
[2]
survival or cancer-specific survival rate . The treatment paradigm historically centered around surgery,
from open one to minimally invasive surgery, such as enucleation or enucleoresection, in order to preserve as
[3]
much as possible healthy renal parenchyma, reducing the risk of chronic kidney disease (CKD) . However,
thanks to more modern technologies, the concept of active surveillance has grown rapidly and nowadays
in selected patients, we could offer a standardized protocol of surveillance or a focal management strategy.
In addition, renal tumor ablation (focal management) has been developed rapidly during the last 2 decades
and currently could be a real alternative option in the opportunely selected candidate to obtain local tumor
[2,3]
control, functional preservation, fewer complications and a shorter recovery in comparison to surgery .

The imaging in the context of ablation therapy for SRMs is a cornerstone that is needed in all the pathway
schedules: from diagnosis to treatment and eventually for surveillance and follow-up protocols. Hence, in
this review, we critically assess recent literature on the role of imaging in the context of minimally invasive
management of SRMs, focusing in particular on diagnosis and follow-up after ablative treatment.

IMAGING MODALITIES - DIAGNOSIS
The improvement and wide spreading of ever more efficient imaging techniques have leaded in the last
years to a sensible increase in the diagnosis of incidental renal masses (IRM). Different imaging modalities
are used: (1) ultrasonography (US); (2) contrast enhancement ultrasonography (CEUS); (3) computed
tomography (CT); and (4) magnetic resonance imaging (MRI).

US
In every day clinical practice, US is the first imaging technique that allows the discovery of IRM. Generally,
after having been discovered, IRM are better categorized and staged by using CT scan or abdominal MRI.
The choice is extremely related to the comorbidity of the patients and the presence of a CKD and the
experience of the radiologist.

[4]
According to Oh et al. , US has the sensitivity (SE), specificity (SP), positive predictive value (PPV),
negative predictive value (NPV) and accuracy for renal cell carcinoma (RCC) diagnostic efficacy of 60.5%,
72.7%, 34.8%, 63.6% respectively.

The advange of US included that the target of examination (SMRs) is clearly visible. All the conditions that
limit the US examination, such as obesity or meteorism, represent limits also for CEUS.

CEUS
Otherwise, CEUS has a good potential in the categorization of focal SRMs and has had an increasing use
and widespread adoption worldwide due to its advantages in the evaluation of enhancement pattern of
the renal lesion without the risk of nephrotoxicity and the lack of ionizing radiation. The contrast agent is
made of microbubbles and has no toxic effects on renal parenchyma. As concerning CEUS, PPV, SE, SP,
[4]
NPV are 86.8%, 63.6%, 89.2%, 58.3% and 81.6% respectively, for RCC diagnostic efficacy . CEUS advantages
[5]
include safety, patient tolerance, real-time imaging capability, and costs .
Hence, CEUS could be a useful instrument in the pre-operatively settings for characterization and
diagnosis of SRMs but also in the follow-up, due for its strength in the detection of acute complication and
[6]
early intralesional enhancement .