Fusion Imaging in Neurosonology: Clinician's Questions, Technical Potentials and Applicability

Purpose: Ultrasound is a well established imaging technique with widespread use in diagnosis and treatment monitoring of neurological diseases. However, direct and exact comparison of results from conventional ultrasound with other frequently used diagnostic modalities like magnetic resonance imaging (MRI) or computed tomography (CT) is impaired by different field of views and non-identical imaging planes. A new technical approach - ultrasound fusion imaging might help to overcome this problem. Methods: Fusion imaging is a technique which allows direct comparison of live ultrasound images with exactly corresponding images derived from pre-registered CT or MRI datasets. Different approaches for the matching procedure - manual or automated - can be applied for image fusion and movements of the patient are automatically corrected for. Results: The technique can widely be applied within the field of neurosonology. Clinical examples are given for its use in extra- and intracranial analysis of brain supplying arteries, intracranial parenchymal lesions but also for its use in peripheral nerve and muscle disease. Conclusions: Ultrasound fusion imaging is a promising technique which permits easy and exact matching between live ultrasound and CT or MRI image modalities, allowing for the first time a direct comparison between these techniques. This is a major step forward towards the facilitation of information exchange, reduction of interobserver variability and improvement of image documentation