Is there another diagnostic test that other than an MRI that would show a rupture?

Thank you for your question.
In the case of diagnosing a ruptured silicone implant, an ultrasound and CT is a great substitution to a MRI. I recommend speaking with your plastic surgeon for further evaluation and to address your concerns.

Ultrasound and CT imaging can also be used to detect implant rupture. Ultrasound is an excellent tool for detecting implant rupture that is non-invasive and radiation-free. CT is generally not the first test of choice given its lower sensitivity and specificity. (Silicone looks similar to other tissues on a CT image, making something called extra-capsular rupture more difficult to detect.)
Something called capsular contracture can cause implants to sit higher on the chest and cause an asymmetry between the sides. This can occur with and without rupture of the breast implant.