Minimizing Image Misregistration during PET/CT–guided Percutaneous Interventions with Monitored Breath-hold PET and CT Acquisitions

Abstract

Purpose To validate a monitored, breath-hold positron emission tomography (PET)/computed tomography (CT) acquisition technique for the minimization of respiratory PET/CT image misregistration and lesion distortion during PET/CT–guided percutaneous interventional procedures. Materials and Methods Eleven patients referred for percutaneous biopsy or thermal ablation of tumors near the diaphragm were prospectively enrolled. Initial PET/CT scanning was performed by using a bellows device and monitored, same-level breath-holds for PET and CT acquisitions. Breath-hold PET consisted of nine 20-second breath-hold frames, yielding a 3-minute equivalent PET dataset. A second PET/CT scan was obtained without monitoring by using end-expiration breath-hold CT and free-breathing PET. PET/CT tumor misregistration and craniocaudal tumor diameter were measured on monitored and unmonitored PET/CT datasets. Data were analyzed by using nonparametric, two-sided, signed-rank statistical tests. Results Mean PET/CT image misregistrations in the craniocaudal, anteroposterior, and transverse planes were 2.6 mm (range, 0–7 mm), 3.3 mm (range, 1–8 mm), and 2.7 mm (range, 0–8 mm) with monitoring and 14.7 mm (range, 0–49 mm), 7.6 mm (range, 1–24 mm), and 4.0 mm (range, 0–12 mm) without monitoring, respectively. Differences were significant for craniocaudal ( P = .0087) and anteroposterior ( P = .014) planes, but not for the transverse plane ( P = .23). Mean craniocaudal target diameter was 2.5 mm (range, −2 to 9 mm) larger (ie, distorted) for unmonitored versus monitored PET ( P = .061). Conclusions Acquiring PET/CT datasets with respiratory bellows-assisted, monitored breath-holds improves PET/CT image registration versus unmonitored PET/CT and may facilitate accurate targeting during PET/CT–guided interventions in anatomic regions subject to respiratory motion.