The purpose of this study was to prospectively evaluate the two different ultrasound-guided injection techniques for MR arthrography of the hip. 

Fifty-nine consecutive patients (21 men, 38 women) referred for MR arthrographies of the hip were prospectively included in the study. Three patients underwent bilateral MR arthrography. The two injection techniques were quantitatively and qualitatively compared. Quantitative analysis was performed by the comparison of injected contrast material volume into the hip joint. Qualitative analysis was performed with regard to extraarticular leakage of contrast material into the soft tissues. Extraarticular leakage of contrast material was graded as none, minimal, moderate, or severe according to the MR images. Each patient rated discomfort after the procedure using a visual analogue scale (VAS). 

The injected contrast material volume was less in femoral head puncture technique (mean 8.9 +/- 3.4 ml) when compared to femoral neck puncture technique (mean 11.2 +/- 2.9 ml) (p < 0.05). The chi-squared test showed significantly more contrast leakage by femoral head puncture technique (p < 0.05). Statistical analysis showed no difference between the head and neck puncture groups in terms of feeling of pain (p = 0.744) or in the body mass index (p = 0.658) of the patients. 

The femoral neck injection technique provides high intraarticular contrast volume and produces less extraarticular contrast leakage than the femoral head injection technique when US guidance is used for MR arthrography of the hip.