Effects of repetitive freeze-thawing cycles on T2 and T2 of the Achilles tendon.
BACKGROUND
In this study we sought to evaluate the effects of multiple freezing and thawing cycles on two MR parameters to study Achilles tendon, T2 and T2.


METHODS
Four fresh Achilles tendons were imaged on a 3T clinical scanner and again after 1, 2, 4, and 5 freeze-thaw cycles with spin-echo (SE) and ultrashort echo time (UTE) sequences. Regions of interest were manually drawn over the entire Achilles tendon and mono-exponential curves were used to determine T2 and T2 relaxation times.


RESULTS
There was no statistically significant difference in mean T2 or T2 values between the fresh specimens and after subsequent cycles of freeze-thaw treatment (p>0.1). Linear regression between SE T2 values at baseline and after successive freeze-thaw cycles demonstrated moderate agreement (r=0.60) whereas UTE T2 values at baseline and after successive-freeze thaw cycles demonstrated strong agreement (r=0.92).


CONCLUSIONS
These findings suggest that changes between specimens seen in vitro are due to factors other than frozen storage. Furthermore, our results suggest that there is stronger agreement between baseline (fresh) and successive freeze-thaw T2 values of tendon obtained with the UTE technique in comparison to T2 values obtained with a conventional clinical CPMG technique.
Department of Radiology, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, United States; Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103, United States. Electronic address: ericchangmd@gmail.com.
Eric Y
EY
Chang
Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103, United States. Electronic address: wbae@ucsd.edu.
Won C
WC
Bae
Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103, United States. Electronic address: sherondastatum@msn.com.
Sheronda
S
Statum
Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103, United States. Electronic address: jiangdu@ucsd.edu.
Jiang
J
Du
Department of Radiology, University of California, 200 West Arbor St., San Diego, CA 92103, United States; Department of Radiology, VA San Diego Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, United States. Electronic address: cbchung@ucsd.edu.
Christine B
CB
Chung
D000125:Achilles Tendon / Q000033:anatomy & histology* / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005615:Freezing; D006361:Heating; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009926:Organ Preservation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
Achilles tendon; Freeze–thaw; T2; T2*; UTE