US & MR/CT Image Fusion with Markerless Skin Registration: A Proof of Concept.

This paper presents an innovative automatic fusion imaging system that combines 3D CT/MR images with real-time ultrasound acquisition. The system eliminates the need for external physical markers and complex training, making image fusion feasible for physicians with different experience levels. The integrated system involves a portable 3D camera for patient-specific surface acquisition, an electromagnetic tracking system, and US components. The fusion algorithm comprises two main parts: skin segmentation and rigid co-registration, both integrated into the US machine. The co-registration aligns the surface extracted from CT/MR images with the 3D surface acquired by the camera, facilitating rapid and effective fusion. Experimental tests in different settings, validate the system's accuracy, computational efficiency, noise robustness, and operator independence.

Real-Time US-18FDG-PET/CT Image Fusion for Guidance of Thermal Ablation of 18FDG-PET-Positive Liver Metastases: The Added Value of Contrast Enhancement.

PURPOSE: To assess the feasibility of US-18FDG-PET/CT fusion-guided microwave ablation of liver metastases either poorly visible or totally undetectable with US, CEUS and CT, but visualized by PET imaging. MATERIALS AND METHODS: Twenty-three patients with 58 liver metastases underwent microwave ablation guided by image fusion system that combines US with 18FDG-PET/CT images. In 28/58 tumors, 18FDG-PET/CT with contrast medium (PET/CECT) was used. The registration technical feasibility, registration time, rates of correct targeting, technical success at 24 h, final result at 1 year and complications were analyzed and compared between the PET/CT and PET/CECT groups. RESULTS: Registration was successfully performed in all cases with a mean time of 7.8 + 1.7 min (mean + standard deviation), (4.6 + 1.5 min for PET/CECT group versus 10.9 + 1.8 min for PET/CT group, P < 0.01). In total, 46/58 (79.3%) tumors were correctly targeted, while 3/28 (10.7%) and 9/30 (30%) were incorrectly targeted in PET/CT and PET/CECT group, respectively (P < 0.05). Complete ablation was obtained at 24 h in 70.0% of cases (n = 40 tumors), 23/28 (82.1%) in the PET/CECT group and 17/30 (56.7%) in the PET/CT group (P < 0.037). Fourteen tumors underwent local retreatment (11 ablations, 2 with resection and 1 with stereotactic body radiation therapy), while 4 tumors could not be retreated because of distant disease progression and underwent systemic therapy. Finally, 54/58 (93.1%) tumors were completely treated at 1 year. One major complication occurred, a gastrointestinal hemorrhage which required surgical repair. CONCLUSIONS: Percutaneous ablation of 18FDG-PET-positive liver metastases using fusion imaging of real-time US and pre-acquired 18FDG-PET/CT images is feasible, safe and effective. Contrast-enhanced PET/CT improves overall ablation accuracy and shortens procedural duration time.

Real-time US-CT/MRI image fusion for guidance of thermal ablation of liver tumors undetectable with US: results in 295 cases.

PURPOSE: This study was designed to assess feasibility of US-CT/MRI fusion-guided ablation in liver tumors undetectable with US. METHODS: From 2002 to 2012, 295 tumors (162 HCCs and 133 metastases; mean diameter 1.3 ± 0.6 cm, range 0.5-2.5 cm) detectable on contrast-enhanced CT/MRI, but completely undetectable with unenhanced US and either totally undetectable or incompletely conspicuous with contrast-enhanced US (CEUS), were treated in 215 sessions using either internally cooled radiofrequency or microwave with standard ablation protocols, guided by an image fusion system (Virtual Navigation System, Esaote S.p.A., Genova, Italy) that combines US with CT/ MRI images. Correct targeting and successful ablation of tumor were verified after 24 hours with CT or MRI. RESULTS: A total of 282 of 295 (95.6 %) tumors were correctly targeted with successful ablation achieved in 266 of 295 (90.2 %). Sixteen of 295 (5.4 %) tumors were correctly targeted, but unsuccessfully ablated, and 13 of 295 (4.4 %) tumors were unsuccessfully ablated due to inaccurate targeting. There were no perioperative deaths. Major complications were observed in 2 of the 215 treatments sessions (0.9 %). CONCLUSIONS: Real-time virtual navigation system with US-CT/MRI fusion imaging is precise for targeting and achieving successful ablation of target tumors undetectable with US alone. Therefore, a larger population could benefit from ultrasound guided ablation procedures.

Virtual navigator 3D panoramic for breast examination.

Breast examination both for screening and second level of investigation has spread worldwide, due to increased breast cancer awareness. Thus, different diagnostic imaging technologies emerged in breast application. Ultrasound (US), a real-time examination, non-invasive, cost effective, ideal also for repetitive follow-up and able to give information about anatomy, hemodynamics and tissue stiffness, plays an important role in breast diagnostics. The present work describes the innovative three-dimensional (3D) Panoramic (Pan) tool of Virtual Navigator technology for real-time fusion imaging of breast 3D US volumes with bi-dimensional US scans. A Motion Control Sensor enables the correction of the examined subject's movements. Data about fusion precision and system performances will be presented regarding tests in vitro, in ex-vivo and in vivo.

Virtual navigator real-time ultrasound fusion imaging with positron emission tomography for liver interventions.

Real-time fusion imaging technologies are increasingly being used among interventional radiologists, mostly Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) dataset, fused with Ultrasound (US) imaging. In addition, fusion of Positron Emission Tomography (PET) and CT is increasingly diffused in clinical practice, due to the wide availability of PET scanners and the capability to make either a direct (acquisitions performed within the same system) or an indirect (procedure performed on an external workstation, merging the two different sets of acquired data) fusion with CT data. The present work describes the feasibility of real-time fusion imaging directly between PET data and US imaging, with CT scans being used only for PET-US fusion registration. Data on multimodality registration precision and clinical applications are presented as well.

Assessment of the cerebral venous system from the transcondylar ultrasound window using virtual navigator technology and MRI.

The Chronic Cerebro-Spinal Venous Insufficiency, recently described as a possible role in Multiple Sclerosis pathogenesis, is diagnosed and classified with Echo Color Doppler (ECD) examination of the extra- and intra-cranial veins. As to the intracranial examination, the presence of reflux in the deep cerebral veins (DCVs) or in the dural sinuses is inspected, with a new insonation approach, i.e. the transcondylar window. This work describes a procedure for the co-registration of anatomical Proton Density-weighted Magnetic Resonance Images (MRI) with the intracranial ECD obtained through the transcondylar window. The procedure, preliminarily tested on 10 volunteers, allowed to assess what are the DCVs visible from this new insonation approach and their position relative to the surrounding brain tissues.