7 Tesla quantitative hip MRI: a comparison between TESS and CPMG for T2 mapping.
OBJECTIVE
We aimed to evaluate the feasibility of triple-echo steady state (TESS) T2 mapping as an alternative to conventional multi-echo-spin-echo (CPMG) T2 mapping for the quantitative assessment of hip joint cartilage at 7 T.


METHODS
A total of eight healthy volunteers and three patients were included. Reproducibility of both techniques was evaluated in five volunteers in five scans each. T2 relaxation times were measured by manually drawing regions of interest in multiple regions of the hip joint. Data from both methods were compared using Pearson correlation coefficient, intra-class correlation coefficient, and coefficient of repeatability. The overall image quality and presence of artifacts was assessed.


RESULTS
Cartilage transplant and surrounding fluid were well depicted by both methods. Compared to CPMG, TESS provided systematically reduced T2 values (43.3 ± 7.3 vs. 19.2 ± 5.5 ms for acetabular cartilage, and 41.4 ± 5.6 vs. 21.7 ± 5.2 ms for femoral cartilage), in line with previously reported values. No correlation between both methods was found. TESS yielded a slightly better reproducibility than CPMG, while CPMG showed pronounced sensitivity to B1 inhomogeneities.


CONCLUSIONS
TESS seems to be an attractive alternative to CPMG for improvements in quantitative hip joint imaging at 7 T, allowing shortening of the total acquisition time paired with insensitivity to B1, while rendering comparable image quality with good repeatability.
Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Kokereiallee 7, Building C84, 45141, Essen, Germany. oliver.kraff@uni-due.de.
Oliver
O
Kraff
Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Kokereiallee 7, Building C84, 45141, Essen, Germany.|Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
Andrea
A
Lazik-Palm
Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.|Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Rahel
R
Heule
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
Jens M
JM
Theysohn
Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland.|Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Oliver
O
Bieri
Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Kokereiallee 7, Building C84, 45141, Essen, Germany.|High Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany.
Harald H
HH
Quick
D000077:Acetabulum / Q000000981:diagnostic imaging; D000328:Adult; D000465:Algorithms; D002358:Cartilage, Articular / Q000000981:diagnostic imaging; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D064368:Healthy Volunteers; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D055815:Young Adult
7 T; Hip joint; Magnetic resonance imaging; T2 relaxometry; Ultra-high field