Interventional respiratory motion compensation by simultaneous fluoroscopic and nuclear imaging: a phantom study

Abstract

Purpose. A compact and mobile hybrid c-arm scanner, capable of simultaneously acquiring nuclear and fluoroscopic projections and SPECT/CBCT, was developed to aid fluoroscopy-guided interventional procedures involving the administration of radionuclides (e.g. hepatic radioembolization). However, as in conventional SPECT/CT, the acquired nuclear images may be deteriorated by patient respiratory motion. We propose to perform compensation for respiratory motion by extracting the motion signal from fluoroscopic projections so that the nuclear counts can be gated into motion bins. The purpose of this study is to quantify the performance of this motion compensation technique with phantom experiments. Methods. Anthropomorphic phantom configurations that are representative of distributions obtained during the pre-treatment procedure of hepatic radioembolization were placed on a stage that translated with three different motion patterns. Fluoroscopic projections and nuclear counts were simultaneously acquired under planar and SPECT/CBCT imaging. The planar projections were visually assessed. The SPECT reconstructions were visually assessed and quantitatively assessed by calculating the activity recovery of the spherical inserts in the phantom. Results. The planar nuclear projections of the translating anthropomorphic phantom were blurry when no motion compensation was applied. With motion compensation, the nuclear projections became representative of the stationary phantom nuclear projection. Similar behavior was observed for the visual quality of SPECT reconstructions. The mean error of the activity recovery in the uncompensated SPECT reconstructions was 15.8% ± 0.9% for stable motion, 11.9% ± 0.9% for small variations, and 11.0% ± 0.9% for large variations. When applying motion compensation, the mean error decreased to 1.8% ± 1.6% for stable motion, 2.2% ± 1.5% for small variations, and 5.2% ± 2.5% for large variations. Conclusion. A compact and mobile hybrid c-arm scanner, capable of simultaneously acquiring nuclear and fluoroscopic projections, can perform compensation for respiratory motion. Such motion compensation results in sharper planar nuclear projections and increases the quantitative accuracy of the SPECT reconstructions.

A compact and mobile hybrid C-arm scanner for simultaneous nuclear and fluoroscopic image guidance

“…The phantom experiments showed that the SPECT image quality of IXSI was lower than that of a clinical scanner due to the placement of the flat panel detector in front of the gamma camera and the change from two to one detector head. However, in the case of imaging during radioembolization, it has through digital and experimental studies [9,[17][18][19] been demonstrated that IXSI can be expected to accurately retrieve various clinically and dosimetric important measures. The clinical performance of IXSI in other procedures is under active investigation.…”

Effects of movement artifacts in nuclear hybrid modalities for image diagnostic

“…In other studies, a segmentation was applied by the threshold for different spheres with volumes from 10 mm to 37 mm of diameter, and the reported threshold values between 40% and 45% depending on the S/B ratio, volume and sphere diameter; similar parameters were used in this work. Considering these parameters is possible to apply this methodology in clinical studies, especially in treatments that imply respiratory motion [2], [17], perfusion in cardiology studies [3], radioembolization in liver with microspheres of 90Y [18], [19]. A threshold procedure is necessary for a correct image delineation in segmentation, including the area and volume delimitation to improve the resolution for SPECT/CT studies.…”

“…One of the most common hybrid equipment in Nuclear Medicine services is the Single-photon Emission Computed Tomography (SPECT-CT) which allows the combination of the metabolic information provided by the volumetric image generated by the gamma camera (that allows the obtention of three-dimensional representations of the radiopharmaceutical distribution in the patient), and by the anatomical information provided by the Computer Tomography (CT) images. The use of phantoms represent a common practice in imaging acquisition procedures both for parameter setting and for radiopharmaceutical dosimetry evaluation (phantoms can be of different shapes, sometimes amorphous and with a defined form and unique characteristics, it depends of the body regions and organs on study) [2], [3]. Additionally, the organ motion produced by respiratory and cardiac movements is still a significant challenge for the accurate delivery of radiotherapy and diagnostics when using hybrid equipment [4]- [7].…”

Dosimetric impact of 3D motion-compensated SPECT reconstruction for SIRT planning

“…While the first three phenomena are routinely accounted for by reconstruction software, breathing motion is usually not corrected. Different methods have been proposed in the literature to retrieve and correct for breathing motion in SPECT images, e.g., using external breathing monitoring device [15], fluoroscopic images [16,17] or data-driven approaches [18,19]. Motion correction was, for example, applied to myocardial perfusion [20,21].…”