US is considered the modality of choice for neck soft-tissue examination,
image guided neck interventional procedure and in particular FNA or core biopsies.
Even if standard B-mode US examinations can be integrated with advanced imaging techniques such as color-Doppler,
contrast-enhanced ultrasound and elastosonography,
tissue characterization by US still relies mainly on morphological characteristics.
On the other hand,
Scintiscan,
PETCT and MRI can provide valuable specific functional information which is useful for detecting pathologies.
In particular,
while Scintiscan is commonly used in the diagnostic work-up of thyroid and parathyroid disease,
whole body PET-CT scan,
CT and MRI can frequently detect,
even incidentally,
abnormal findings in the soft tissue of the neck [1-2-3-4].
Either way,
clinicians are often most interested in US confirmation and US features and,
ultimately,
in the histological characterization by US guided FNA or core needle biopsy.
Usually,
a cognitive approach is used for creating an alignment between a US scan and functional images,
and defines a correlation between US findings and functional findings.
This technique is intuitive,
inexpensive,
and requires the operator to pinpoint the location of the suspicious lesion via functional imaging within the US images.
Unfortunately,
the cognitive approach is challenging and susceptible to human error as it relies on the operator’s spatial cognition to accurately direct the US probe toward the target [5].
More recently,
real time Virtual navigation by images fusion techniques ( also known as Interactive localizing techniques) has been proposed in order to spatially co-registrate a real time modality (i.e.
US) with high resolution isotropic 3D CT and MRI or functional images (i.e.
PET-CT and scintiscan).
In this way,
the operator can simultaneously use information from multiple imaging modalities to enhance diagnostic and localization capability.
Image fusion can be achieved by electromagnetic (EM),
optical or mechanical devices.
There are some advantages of using EM devices over optical and mechanical device:
a) The tracked device can reside out of generator sight;
b) Multiple devices can be tracked at the same time;
c) Devices can be tracked also within the patient’s body without signal attenuation;
d) There are no significant limitation to operator position and movements.
These advantages make EM tracking systems more flexible,
as well as making them suitable for multipurpose applications.
The main technical limitation of EM tracking systems is that the ferromagnetic environment can cause interference and distortion of magnetic coordinates.
However,
a new generation of EM tracking systems has reduced susceptibility to the effects of the metal hardware [6-7-8].
Other possible drawbacks are the necessity of expensive dedicated images-fusion hardware and software,
and the difficulty of obtaining a precise image fusion considering the anatomical distortion that can be induced by patient movements as well as physiological changes,
or simply by the US probe itself.
The aim of our study is to report a preliminary clinical experience using 3D VN and 2D navigation with BMT for US localization of abnormal findings in neck PET-CT or scintiscan.