CT-guided PTCB is essential for the differential diagnosis between benign and malignant pulmonary and mediastinal tumors and for cellular characterization by somatic mutation and cellular differentiation analysis.
Cellular characterization is becoming more and more important due to the development of oncologic targeted therapies and will be a field of growing interest in the near future[1-2].
For the same reasons,
coaxial core biopsies are currently preferred to cytological specimens,
as it allows multiple large samples to be obtained for molecular analysis.
Many experienced institutions report a low complication rate after a CT-guided transthoracic coaxial core biopsy.
national surveys still report a considerable incidence of major complication and death.
Core biopsies is more demanding than fine needle aspiration and requires special technical considerations [1-3-4].
While many radiologists still need improved technical training,
it is out of doubt that a widespread implementation of technological innovations will be effective in reducing procedure-related complications.
Usually PTCB is performed under cognitive-CT-guidance.
On the basis of previous diagnostic modality (usually MDCT or PETCT) the patient is positioned on the CT table in the most convenient position (supine,
prone etc.) for the safest approach to the lesion.
A metal grid is attached to the patient’s skin in an area planned for skin punctures.
the skin entry point is marked and local anesthesia is performed.
Using the skin entry point,
the biopsy needle is then advanced towards the target at the predetermined angle under cognitive guidance.
This technique is inexpensive but is susceptible to human error as it depends on a complex set of processes based on mental perception,
learning and reasoning.
Often the needle requires repositioning several times in order to reach the target satisfactorily.
For these technical difficulties,
usually a trajectory with a single or simple angle is preferred (i.e.
vertical or horizontal).
In the last decade,
two major technological innovations have been introduced: CT-fluoroscopy and C-Arm-CT.
CT-fluoroscopy gives the unparalleled advantage of a real time visualization of the biopsy needle and lesion.
both techniques have some drawbacks [5-6-7]:
a) They are expensive requiring specific hardware and software;
b) They increase the radiation exposure dose to patients and operators;
c) The geometrical characteristics of C-Am and CT-gantry restrict the operator independence.
In order to overcome the limitations of these techniques,
we explored the application of pure virtual navigation guidance (PVNG) for the biopsy of deep mediastinal and pulmonary lesions.
Virtual navigation by images fusion techniques (also known as Interactive localizing techniques) has been proposed in the last two decades in order to spatially coregistrate a real time modality (i.e.
US) with high resolution isotropic 3D CT and MRI or functional images (i.e.
In this way,
the operator can simultaneously use information from multiple image modalities to enhance diagnostic and localization capability.
Virtual Navigator can also be used if the target organ in not visible under US examination. In this case,
the CT or MR images can still be spatially coregistrated with the guiding device (simply,
the US probe).
target localization and percutaneous procedures will be performed only on the basis of virtual real-time multiplanar reconstructions of CT or MRI 3D acquisition (PVNG).
Image fusion can be achieved by Electro-Magnetic (EM),
optical or mechanical devices.
There are some advantages using EM devices over optical and mechanical devices:
a) The tracked device can reside out of generator sight;
b) The tracked device can be within the patient’s body without signal attenuation;
c) There is no significant limitation to operator position and movement.
These advantages make EM tracking systems flexible as well as suited for multipurpose applications.
The main limitation of EM tracking systems is that a ferromagnetic environment can cause interference and distortion of magnetic coordinates.
a new generation of EM tracking systems has a reduced susceptibility to the effects of the metal hardware .