Photon-counting CT of degenerative changes and rupture of silicone breast implants: a pilot study.

Background: Accurate assessment of breast implants is important for appropriate clinical management. We evaluated silicone properties and diagnostic accuracy for characterizing silicone implants and detecting degenerative changes including rupture in photon-counting computed tomography (PCCT).

Methods: Over 16 months, we prospectively included patients with silicone implants and available breast magnetic resonance imaging (MRI) who received thoracic PCCT performed in prone position. Consensus reading of all available imaging studies including MRI served as reference standard. Two readers evaluated all implants in PCCT reconstructions for degenerative changes. In a subgroup of implants, mean density of silicone, adjacent muscle, and fat were measured on PCCT reconstructions. Contrast-to-noise ratios (CNRs) were calculated for implant-to-muscle and implant-to-fat.

Results: Among 21 subjects, aged 60 ± 13.1 years (mean ± standard deviation) with 29 implants PCCT showed the following: high accuracy for linguine sign, intraimplant fluid (all > 0.99), peri-implant silicone (0.95), keyhole sign (0.90), and folds of the membrane (0.81); high specificity for linguine sign, intraimplant fluid, keyhole sign, folds of the membrane (all > 0.99), and peri-implant silicone (0.98); and high sensitivity for linguine sign and intraimplant fluid (all > 0.99). In a subgroup of 12 implants, the highest CNR for implant-to-muscle was observed on virtual unenhanced reconstructions (20.9) and iodine maps (22.9), for implant-to-fat on iodine maps (27.7) and monoenergetic reconstructions (31.8).

Conclusions: Our findings demonstrate that silicone breast implants exhibit distinct contrast properties at PCCT, which may provide incremental information for detection of degenerative changes and rupture of implants.

Relevance Statement: Thoracic photon-counting computed tomography is a promising modality for the diagnostic assessment of silicone breast implants.

Key Points: • Thoracic photon-counting computed tomography demonstrates unique contrast properties of silicone breast implants. • Iodine map reconstructions reveal strong contrast-to-noise ratios for implant-to-muscle and implant-to-fat. • Thoracic photon-counting computed tomography shows high diagnostic accuracy in detecting implant degeneration and rupture.

Trial Registration: German Clinical Trials Register number DRKS00028997, date of registration 2022-08-08, retrospectively registered.