Clinical History
63-year-old female cyclist was hit by a car on her right side on a road traffic accident. Afterwards brought to the hospital with pain in right side of thorax and breathing difficulty.
Physical examination showed tenderness on palpation on right side of thorax and right breast.
Imaging Findings
Chest X-ray (Fig. 7): Shows apical pneumothorax on right side and suspicion of rib fractures on right side.
Non-contrast CT: Shows apical pneumothorax on right side with right sided rib fractures in 5, 6, 7 and 8th ribs.
Additionally CT examination showed deformity of the silicon implant surface in right breast representing a collapsed ruptured silicon prosthesis (Fig. 1, 2, 5 and 6) with-
(1) “Linguine sign” (Fig. 1 and 2) which is folded in wavy multidirectional lines within the silicone gel, representing the collapsed implant shell.
(2) “Railroad track sign” (Fig. 3) which is two parallel lines in close proximity forming a double-contoured subcapsular line within the silicone gel.
Discussion
BACKGROUND:
Breast implants used for augmentation mammoplasty or breast reconstruction could rupture from various causes such as trauma or spontaneous failure. [1] Rupture of the implant may be contained within the fibrous scar or capsule that forms around the implant, or extracapsular, breaching the capsule. [2] The latter pose a more serious problem than the former because it may inflict damage to the surrounding normal tissues. [1]
IMAGING PERSPECTIVE:
MRI, mammography, ultrasound, and CT have all been used to diagnose silicone breast implant rupture. However, MRI has the highest sensitivity and specificity for detection of silicone implant rupture and is the imaging modality of choice. [3]
MRI:
Silicone has a unique magnetic resonance frequency and long T1 and T2 relaxation times, which allows several magnetic resonance sequences to provide excellent diagnostic images.
The most reliable magnetic resonance criterion for intracapsular rupture is the presence of multiple curvilinear low-signal-intensity lines seen within the high-signal-intensity silicone gel, the so-called ''linguine sign''.
Extracapsular silicone implant rupture, the less common type of implant rupture, is defined as rupture of both the implant shell and the fibrous capsule with macroscopic silicone leakage that extends beyond the fibrous capsule into surrounding tissues. Focal areas of high signal intensity, representing free silicone, can be identified on MRI. [3]
CT EXAMINATION:
CT examination can be used in the evaluation of silicone breast implant failure. Computed tomography is accurate in detecting intracapsular silicone breast implant ruptures and is capable of depicting the ''linguine sign''. Limitation of CT is its limited ability to detect extracapsular silicone because of the similar Hounsfield units between silicone and soft tissues. However, in most cases of extracapsular silicone implant ruptures, one can identify the collapsed implant shell, so a ruptured silicone implant will usually not be missed by CT. [3]
Definitive findings of breast implant rupture on CT and MRI:
(a) Subcapsular lines. Lines running almost parallel to the fibrous capsule and just beneath it. The beginning and the end of the line can be followed to the surface of the implant.
(b) Siliconomas and free silicone. Disruption of the shell and fibrous capsule will allow silicone to extravasate into surrounding breast tissue.
(c) “Linguine sign”. Folded wavy multidirectional lines within the silicone gel, representing the collapsed implant shell.
(d) “Railroad track sign”. Two parallel lines in close proximity forming a double-contoured subcapsular line within the silicone gel. [4]
Differential Diagnosis List
Multiple rib fractures with rupture of right-sided breast implant
Rib fractures
Haemothorax
Pneumothorax
Final Diagnosis
Multiple rib fractures with rupture of right-sided breast implant
