Sonography and MRI of experimental muscle injuries

Abstract

After sonographical examination with a 7.5-MHz linear array scanner, we created an experimental muscle injury of known site and location on 28 New Zealand white rabbits by stabbing them with a scalpel in the supraspinatus muscle. The changes in the healing process were followed and documented by sonography and magnetic resonance imaging (MRI) before and 2, 5, 11, 14, 36 and 64 days after injury. The changes in sonography and MRI followed a regular course. Ultrasound revealed an echo-poor area after injury with ever increasing echogenicity from the 14th day. Strong reflexes were found after 2 months. MRI showed few changes, only a slight increase of signal intensity, but a characteristic curve of calculated T2-times (a program of the MRI software). The interpretation of the sonographical picture in histopathological terms remained limited. The development of a hematoma and of fibrous scars can be followed up by sonography, but it is not possible to determine the point of time after injury very accurately. Nevertheless, sonography is a method of great value in the diagnosis of muscle injuries and, given certain limits, in the follow-up of the healing process, too. The significance of MRI can be increased by calculations with the implemented software, as in our study calculated T2-times produced a characteristic curve reflecting the shift of fluids after muscle injury.

Structural changes in puborectalis muscle after vaginal delivery

“…One day after delivery, there was a sharp decrease in MEP, most likely due to (micro) hematoma and edema, since fluid appears dark on ultrasound image. The (small) increase in PMA at 1 day after delivery (statistically significant during contraction) compared with PMA during pregnancy is also probably due to (micro) hematoma and edema.…”

Evaluation of polyamide surgical mesh as an abdominal ventral implant in rabbits

“…The healing tissue that filled the gap between the muscle edges had a heterogenic areas interspersed with hyperechoic and hypoechoic areas. This suggested formation of scarring tissue 10 . In the comparison between the immediate and 180day postsurgical examinations, we observed a constant tissue organization until a plateau at 120 days after surgery.…”

Serial MR Imaging of Intramuscular Hematoma: Experimental Study in a Rat Model with the Pathologic Correlation

“…Skeletal muscle has been shown, both biomechanically and histologically, to have an extensive ability to recover after laceration injury (8, 23, 24). Kääriäinen and associates (24) studied soleus muscle repair after injury, and by day 56, the regenerating myofibers had formed a well-organized structure of interlacing fibers.…”

“…The magnetic resonance imaging (MRI) signal patterns of hematomas are strongly affected by the hemoglobin breakdown products and these patterns can best be understood by taking into account the magnetic properties of hemoglobin and its metabolites (4). Although the MRI signal intensity pattern of blood in the brain has been well documented (5-7), the mechanisms of both muscular hematoma and its healing differ from those of intracranial hematoma (8-10). In addition, an intramuscular hematoma can mimic a hemorrhagic neoplasm (4).…”