Investigation of a SPECT/computed tomography imaging artefact and its impact on SPECT quantification

Area of Science:

• Nuclear medicine
• Medical imaging
• Radiopharmacology

Background:

• An artifact affecting single photon emission computed tomography (SPECT) quantification was identified during L-mode parathyroid imaging optimization.
• This artifact could potentially impact the accuracy of parathyroid imaging results.

Purpose of the Study:

• To assess H-mode SPECT for the identified artifact.
• To compare artifact differences for [99mTc] and [123I] tracers, with and without non-specific background.
• To evaluate the artifact's impact on clinically relevant areas in parathyroid imaging.

Main Methods:

• Parathyroid/thyroid phantom studies were conducted using L-mode and H-mode SPECT acquisition protocols.
• Studies simulated non-specific background using saline bags in a Perspex torso.
• Standard Uptake Values (SUVs) were measured in thyroid and artifact regions for [99mTc] and [123I] using Hermia software.

Main Results:

• L-mode SPECTs showed a more prominent artifact with a greater spread of SUVs compared to H-mode SPECTs.
• No significant differences in [99mTc] thyroid SUVs were observed across acquisition modes.
• Significant differences in SUVs were found for [123I] between L-mode and H-mode (P=0.04) and with/without background (P=0.03), with measurable SUVs in artifact areas for L-mode [123I].

Conclusions:

• H-mode SPECT is more robust against the identified artifact, leading to improved quantification accuracy.
• H-mode is preferred for clinical parathyroid imaging due to its superior performance.
• The findings support the adoption of H-mode for more reliable SPECT quantification in parathyroid scintigraphy.