Both 3-T dGEMRIC and Acetabular-Femoral T2 Difference May Detect Cartilage Damage at the Chondrolabral Junction.
BACKGROUND
In addition to case reports of gadolinium-related toxicities, there are increasing theoretical concerns about the use of gadolinium for MR imaging. As a result, there is increasing interest in noncontrast imaging techniques for biochemical cartilage assessment. Among them, T2 mapping holds promise because of its simplicity, but its biophysical interpretation has been controversial.


OBJECTIVE
We sought to determine whether (1) 3-T delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and T2 mapping are both capable of detecting cartilage damage at the chondrolabral junction in patients with femoroacetabular impingement (FAI); and (2) whether there is a correlation between these two techniques for acetabular and femoral head cartilage assessment.


METHODS
Thirty-one patients with hip-related symptoms resulting from FAI underwent a preoperative 3-T MRI of their hip that included dGEMRIC and T2 mapping (symptomatic group, 16 women, 15 men; mean age, 27 ± 8 years). Ten volunteers with no symptoms according to the WOMAC served as a control (asymptomatic group, seven women, three men; mean age, 28 ± 3 years). After morphologic cartilage assessment, acetabular and femoral head cartilages were graded according to the modified Outerbridge grading criteria. In the midsagittal plane, single-observer analyses of precontrast T1 values (volunteers), the dGEMRIC index (T1Gd, patients), and T2 mapping values (everyone) were compared in acetabular and corresponding femoral head cartilage at the chondrolabral junction of each hip by region-of-interest analysis.


RESULTS
In the symptomatic group, T1Gdand T2 values were lower in the acetabular cartilage compared with corresponding femoral head cartilage (T1Gd: 515 ± 165 ms versus 650 ± 191 ms, p < 0.001; T2: 39 ± 8 ms versus 46 ± 10 ms, p < 0.001). In contrast, the asymptomatic group demonstrated no differences in T1 and T2 values for the acetabular and femoral cartilages with the numbers available (T1: 861 ± 130 ms versus 860 ± 182 ms, p = 0.98; T2: 43 ± 7 ms versus 42 ± 6 ms, p = 0.73). No correlation with the numbers available was noted between the modified Outerbridge grade and T1, T1Gd, or T2 as well as between T2 and either T1 or T1Gd.


CONCLUSIONS
Without the need for contrast media application, T2 mapping may be a viable alternative to dGEMRIC when assessing hip cartilage at the chondrolabral junction. However, acquisition-related phenomena as well as regional variations in the microstructure of hip cartilage necessitate an internal femoral head cartilage control when interpreting these results.


METHODS
Level IV, diagnostic study.
Department of Orthopedic Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.
Tobias
T
Hesper
Department of Orthopedic Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.
Evgeny
E
Bulat
Department of Radiology, Boston Children's Hospital, Boston, MA, USA.
Sarah
S
Bixby
Division of Critical Care Medicine, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA, USA.|Harvard Medical School, Boston, MA, USA.
Alireza
A
Akhondi-Asl
Department of Radiology, Boston Children's Hospital, Boston, MA, USA.
Onur
O
Afacan
Department of Orthopedic Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.
Patricia
P
Miller
Department of Orthopedic Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.
Garrett
G
Bowen
Department of Radiology, Boston Children's Hospital, Boston, MA, USA.
Simon
S
Warfield
Department of Orthopedic Surgery, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA. young-jo.kim@childrens.harvard.edu.
Young-Jo
YJ
Kim
D000077:Acetabulum / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D003287:Contrast Media / Q000008:administration & dosage* / Q000009:adverse effects; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging*; D005270:Femur Head / Q000000981:diagnostic imaging*; D019786:Gadolinium DTPA / Q000008:administration & dosage* / Q000009:adverse effects; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D055815:Young Adult
D003287:Contrast Media; D019786:Gadolinium DTPA