Use of 1.5 Tesla and 3 Tesla MRI to evaluate femoral head reduction in hip dysplasia

Background: To date no comparison between 1.5 Tesla (T) and 3 T magnetic resonance imaging (MRI) scans have been performed in assessing hip reduction in patients with hip dysplasia. This study compares the use of these scans in assessing hip reduction. Methods: A retrospective review of 1.5 T and 3 T postreduction pelvic MRIs in developmental dysplasia of the hip patients for scanner time, anesthesia requirement, and subjective image quality scores were performed. Intrareader and interreader agreement of state of hip reduction was assessed. A scoring system was used to objectively compare MRI sequences between the 1.5 T and 3 T scans. Results: Of the 37 MRI scans, scanner time and anesthetic requirement was not significantly different between 1.5 T and 3 T scans (P>0.05). The 3 T scans showed slightly better image quality than 1.5 T scans (5.7 vs. 4.7), but not significant (P=0.08). With regards to state of hip reduction, intrareader Cronbach α was 0.89 with 1.5 T and 0.98 with 3 T, whereas interreader agreement was 0.79 with 1.5 T and 0.95 with 3 T, revealing greater consistency with 3 T. Mean anatomic score comparison of hip anatomic markers show no overall statistical difference between fast hip protocol sequences (f=1.113, sig=0.346) or magnet strength (f=3.817, sig=0.053). Only the coronal T2W fast spin echo demonstrated a statistically higher score on the 3 T versus the 1.5 T (19.3±9.3 vs. 12.2±6.7) scanner. Conclusions: Our study affirms that adequate images are obtainable with fast hip MRI without additional anesthesia. Good agreement was reached on image quality and hip state of reduction between readers for 1.5 T and 3 T scans, with more consistency with 3 T. Level of evidence: Diagnostic Level II.