Evaluation of the effect of breast implants on the accuracy of the CT attenuation Correction (CTAC) map for SPECT/CT myocardial perfusion imaging: a phantom study

Alanezi, A

Abstract

Background: Myocardial perfusion imaging (MPI) using single photon emission computed
tomography (SPECT) imaging can assess myocardial viability and perfusion. However,
overlying thoracic structures, such as ribs or breast tissue lead to gamma ray attenuation. This
attenuation does not occur equally for all body regions. Photons emitted from deeper structures
will undergo more attenuation than superficial structures, causing artefacts within the image
that can mimic pathology - such as ischaemia. Such artefacts can be removed or minimised by
using attenuation correction (AC) maps generated using computed tomography (CT). Breast
implants that have density higher than normal breast tissue, could affect the accuracy of the CT
numbers used for AC.
Methods: Imaging protocols were compared with and without three sizes of breast implant, in
a phantom study. The first experiment used a diagnostic CT scanner to design the method. The
second experiment was carried out in a clinical centre using the CT components of a SPECT/CT
scanner to assess the impact of three different breast implants on CT number accuracy when
the CTAC is applied in SPECT/CT MPI. The last experiment used a clinical SPECT/CT
scanner and 99mTC as a radiotracer to mimic the clinical MPI scan.
Results: The first and second experiments found that large breast implants led to a greater
difference in CT HU and CT numbers compared to baseline, than the small or medium implants,
but the differences were within the tolerance range (±5HUs). This suggested that even large
breast implants did not impact in a clinically significant way on the accuracy of CT HUs and
CT numbers. However, the third experiment found that large breast implants resulted in a more
significant difference in corrected counts and thus more overcorrection than small or medium
breast implants.
Conclusion: The study illustrates that large breast implants resulted in a greater differences in
CT HUs, CT number and corrected counts than small or medium implants. Increasing the tube
current (mA) improves the CT HU accuracy without significant impact, apart from an increase
in the radiation dose to the patient.

Citation

Alanezi, A. Evaluation of the effect of breast implants on the accuracy of the CT attenuation Correction (CTAC) map for SPECT/CT myocardial perfusion imaging: a phantom study. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Feb 2, 2023
• Publicly Available Date: Feb 2, 2023
• Award Date: Feb 1, 2022