Respiratory motion compensation in interventional liver SPECT using simultaneous fluoroscopic and nuclear imaging

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiotherapy Physics

Background:

• Quantitative accuracy and visual quality of SPECT reconstruction are vital for liver radioembolization dosimetry and detecting extra-target doses.
• Respiratory motion degrades SPECT quantitative accuracy, while conventional gating increases noise and reduces visual quality.
• Existing motion compensation methods require external devices and pre-acquired motion data, which may not reflect intra-interventional motion.

Purpose of the Study:

• To evaluate a novel motion compensation approach for interventional liver SPECT using simultaneous fluoroscopic and nuclear data.
• To assess the performance of motion compensation in improving quantitative accuracy and visual quality of SPECT reconstructions.
• To eliminate the need for patient-attached devices for motion signal measurement in interventional SPECT.

Main Methods:

• Generated nuclear and fluoroscopic projections of a digital phantom with respiratory motion using Monte Carlo simulations.
• Extracted motion signal from fluoroscopic projections (1-5 Hz) and reconstructed motion vector fields for SPECT reconstruction.
• Compared the proposed method with conventional gating, analyzing the influence of breathing patterns, dose, sampling rate, and scan time.

Main Results:

• Accurate liver motion signal extraction from fluoroscopic projections was achieved with stable motion and >2 Hz sampling rate.
• The proposed method improved quantitative accuracy and visual quality of SPECT reconstructions compared to conventional gating.
• Enhanced visualization of low-contrast features was observed with the proposed method, with a minimal fluoroscopic dose increase (10 µGy for 5-min scan).

Conclusions:

• The proposed motion compensation method significantly enhances SPECT reconstruction quality for interventional liver procedures.
• This approach eliminates the need for external motion-measuring devices and provides accurate motion vector fields.
• The method shows strong potential for clinical adoption due to improved accuracy, visual quality, and minimal dose increase.