MRI-based AC for SPECT v1.0
Research type
Research Study
Full title
Magnetic Resonance Imaging based Attenuation Correction for Single Photon Emission Computed Tomography
IRAS ID
229856
Contact name
Hugh J Wallace
Contact email
Sponsor organisation
NHS Greater Glasgow and Clyde
Duration of Study in the UK
1 years, 3 months, 1 days
Research summary
Single Photon Emission Computed Tomography (SPECT) provides a non-invasive, direct measure of physiological function within the body. To perform a SPECT scan, a patient is first administered with a radioactive tracer designed to target a specific chemical pathway within the body. Gamma-rays emitted by the tracer are then collected outside the patient by a gamma-camera. The collected gamma-rays are then used to reconstruct a 3-dimensional image of tracer distribution within the body.
Ideally this distribution would be expressed as a tracer concentration at each point of interest within the patient; however there are a number of physical processes which confound the ability of SPECT to achieve this level of quantification. The most significant of these effects is photon attenuation (i.e. absorption) within the patient. The attempt to eliminate this effect is known as attenuation correction (AC). In modern SPECT imaging AC is achieved through the acquisition of a computed tomography (CT) scan immediately following SPECT acquisition; the CT data is then converted to an attenuation map and incorporated into the SPECT reconstruction process. The main disadvantage of this technique is the additional dose burden associated with the addition of CT.
The Royal Hospital for Children in Glasgow has been developing closer integration of MRI and SPECT over the last 5 years and therefore has a significant interest in the development of MRI-based AC for SPECT. MRI requires no additional dose burden to the patient, but is derived from an entirely unrelated physical process so the direct creation of an attenuation map is impossible. While some indirect methods for generating AC from MRI have been demonstrated for the related modality of positron emission tomography (PET), there has been essentially no development of MRI-based AC for SPECT.
This study proposes to make use of fully anonymised, spatially registered MRI and CT data acquired as part of a previous research study at the Beatson West of Scotland Cancer Centre. These datasets will be used to implement MRI-based AC as discussed in the PET literature. The attenuation maps derived from MRI will be compared to those generated from CT. Simulated SPECT data will also be generated and used to assess the potential clinical significance of the differences between MRI-based and CT-based AC for SPECT.REC name
London - Westminster Research Ethics Committee
REC reference
17/LO/1605
Date of REC Opinion
25 Sep 2017
REC opinion
Favourable Opinion