O Kenechi Nwawka1,2, Nicholas Gutierrez3, Bin Lin3, Lydia M Ko3, Theodore T Miller3,4. 1. Department of Radiology and Imaging, Hospital for Special Surgery, 535 East 70th Street, 3rd Floor, New York, NY, 10021, USA. nwawkao@hss.edu. 2. Department of Radiology, Weill Cornell Medical College of Cornell University, New York, NY, USA. nwawkao@hss.edu. 3. Department of Radiology and Imaging, Hospital for Special Surgery, 535 East 70th Street, 3rd Floor, New York, NY, 10021, USA. 4. Department of Radiology, Weill Cornell Medical College of Cornell University, New York, NY, USA.
Abstract
OBJECTIVE: To quantitatively assess changes in muscle stiffness following intramuscular saline injection using shear wave elastography (SWE). MATERIALS AND METHODS: Thirty muscles (lateral deltoid (LD), biceps brachii (BB), brachialis, pronator teres (PT), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU)) from fresh-frozen cadaveric specimens were injected with saline under ultrasound guidance. Pre- and post-injection muscle thickness (MT) (mm) and SWE (kPa) measurements were recorded. RESULTS: All muscles demonstrated a decrease in the mean SWE value post-injection, with the largest differences ± standard error noted in the LD (14.76 ± 3.55 kPa, p = 0.021) and brachialis muscles (12.02 ± 2.51 kPa, p = 0.013). Muscle thickness increased following injection, although the degree of changes poorly correlated with the change in SWE. CONCLUSION: In summary, following intramuscular injection of saline injection, a decrease in upper extremity muscle stiffness is detected using SWE. It is important to note that if performing a longitudinal assessment of muscle stiffness after intramuscular injection, saline will likely contribute to a decrease in muscle stiffness in the immediate post-injection time period.
OBJECTIVE: To quantitatively assess changes in muscle stiffness following intramuscular saline injection using shear wave elastography (SWE). MATERIALS AND METHODS: Thirty muscles (lateral deltoid (LD), biceps brachii (BB), brachialis, pronator teres (PT), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU)) from fresh-frozen cadaveric specimens were injected with saline under ultrasound guidance. Pre- and post-injection muscle thickness (MT) (mm) and SWE (kPa) measurements were recorded. RESULTS: All muscles demonstrated a decrease in the mean SWE value post-injection, with the largest differences ± standard error noted in the LD (14.76 ± 3.55 kPa, p = 0.021) and brachialis muscles (12.02 ± 2.51 kPa, p = 0.013). Muscle thickness increased following injection, although the degree of changes poorly correlated with the change in SWE. CONCLUSION: In summary, following intramuscular injection of saline injection, a decrease in upper extremity muscle stiffness is detected using SWE. It is important to note that if performing a longitudinal assessment of muscle stiffness after intramuscular injection, saline will likely contribute to a decrease in muscle stiffness in the immediate post-injection time period.