DIFFERENTIATION BETWEEN NORMAL RENAL TISSUE AND RENAL TUMOURS USING FUNCTIONAL OPTICAL COHERENCE TOMOGRAPHY: A PHASE I IN VIVO HUMAN STUDY

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In an era of frequent renal incidentaloma diagnosis, the rate of invasive treatment for small renal tumours has drastically increased [1]. Taking into consideration the fact that 20% of these tumours could be benign, every effort should be made to differentiate normal from malignant tissues before any invasive treatment, either minimal or major [2].

Although renal biopsy is highly diagnostic, it is still invasive and liable to false-negative results. Imaging of renal tumours up to now has been more accurate for large tumours, losing its differentiating accuracy as the tumour size decreases [1,2].

Optical coherence tomography (OCT), an optical equivalent of B-mode ultrasonography, provides thin-slice cross-sectional images of high resolution that may resemble and consequently reflect tissue pathology [3].

The current study is the first to assess the ability of OCT to differentiate renal tumour tissue from normal renal parenchyma in an in vivo setting in humans. Despite the fact that this is a pilot study recruiting a small number of patients, the results are promising. For the first time in vivo it is shown that OCT can differentiate normal from benign renal tissue. Could anybody imagine in the future the use of this imaging modality for accurate diagnosis, differentiation and staging of renal tumours, or the combination of OCT with other techniques such as spectroscopy [4].

The current study, in accordance with its limitations, did not show any difference in the OCT signal between benign and malignant tumours. One, correctly, could say that this limits the use of OCT and its significance as a method. However, the small number of the cases included in the study prevents the drawing of definitive conclusions. More importantly, taking into consideration the correct principal of the technique, advancement in OCT probe technology may in future make this technology more accurate in its detection of malignant tumours. The same result could be achieved using a combination of OCT with other technologies, as previously discussed.

We should wait for the results of larger testing trials as well as for the results of validating trials of the different technical issues of OCT technology.

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