Novel way for correcting breast attenuation in myocardial perfusion imaging: Converting non-unifom breast in to uniform one

Objectives Attenuation caused by breast often results in artifacts in myocardial perfusion imaging and either interpretation is made around this artifact or correction is performed using CT or Gd transmission maps. We hypothesize that the attenuation artifacts can be reduced by converting non uniform attenuation caused by breast into a more uniform one by filling in the space around the breasts with material having properties similar to the breast attenuation. To test this hypothesis the following study using phantoms was performed.

Methods Using 0.750mCi of 99m TcO4 in a myocardial phantom in a water filled anthropomorphic chest phantom SPECT images were obtained for three different configurations: (1) without breast attenuators; (2) with breast attenuators in orthotopic positions (creating a non uniform attenuation); (3) with breast attenuators in orthotopic positions plus and saline bags between the breasts (to make a more uniform attenuation). Experiments were repeated thrice. Experiments were repeated with a defect in the anterior wall.The images were reconstructed using Astonish(Phillips) and displayed using autoquant. Qualitative assessment was performed.

Results As expected phantoms without breast attenuators showed lateral wall more photon intense than the septum. When breast attenuator were placed orthotopically the lateral was less intense than septum. In acquisition where the saline bags were placed in between the breast attenuators the lateral wall and septum became more isointense than with breasts without added attenuation. The defect introduced was visualized in all the three acquisitions.

Conclusions The qualitative analysis in a phantom study showed that effects of breast attenuation can be reduced by turning the non uniform attenuation into a more uniform one.