Ultra-high-field MRI of knee joint at 7.0T: preliminary experience.
OBJECTIVE
To measure signal-to-noise ratio (SNR), contrast, and relaxation times (T1 and T2) in human knee joint at 7.0T whole-body scanner.


METHODS
MRI experiments were performed on a 7.0T Siemens whole-body scanner using an 18-cm diameter transmit/receive knee coil. Normalized SNR and relaxation times (T1 and T2) were computed on all volunteers (healthy, n=5) for femoral, tibial, and patellar cartilage.


RESULTS
Average T1 values of femoral, tibial, and patellar cartilages were found as 1.55, 1.76, and 1.62 seconds, respectively. Average T2 values of femoral, tibial, and patellar cartilages were found as 51.3, 43.9, and 39.7 milliseconds, respectively. No statistically significant differences were observed between T1 and T2 values of different cartilage tissues (P>.08 for all comparisons). Compared with previously reported relaxation times of cartilage tissue at 3.0T, an approximately 35% increase was observed in T1 values, whereas no significant change was observed in T2. Regional analysis was also performed to investigate the change in relaxation parameters for weight-bearing vs. non-weight-bearing areas. A statistically significant difference was observed in T2 of tibial cartilage (P=.009). The rest of the comparisons yielded insignificant differences (P>.32).


CONCLUSIONS
Our preliminary results demonstrate the feasibility of acquiring high resolution three-dimensional images of knee joint (with and without fat suppression) at 7.0T whole-body scanner.
Pakin
S Kubilay
SK
Department of Radiology, The Center for Biomedical Imaging, New York University, 660 First Avenue, Ground Floor, New York, NY, USA. skpakin@yahoo.com
Cavalcanti
Conrado
C
La Rocca
Renata
R
Schweitzer
Mark E
ME
Regatte
Ravinder R
RR
D000328:Adult; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008297:Male; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers; D051598:Whole Body Imaging / Q000295:instrumentation* / Q000379:methods