MRI of Pelvic Floor Dysfunction: Dynamic True Fast Imaging with Steady-State Precession Versus HASTE

OBJECTIVE. The objective of our study was to retrospectively compare the degree of pelvic organ prolapse shown on dynamic true fast imaging with steady-state precession (FISP) versus HASTE sequences in symptomatic patients. MATERIALS AND METHODS. Fifty-nine women (mean age, 57 years) with suspected pelvic floor dysfunction underwent MRI using both a sagittal true FISP sequence, acquired continuously during rest alternating with the Valsalva maneuver, and a sagittal HASTE sequence, acquired sequentially at rest and at maximal strain. Data sets were evaluated in random order by two radiologists in consensus using the pubococcygeal line (PCL) as a reference. Measurement of prolapse was based on a numeric grading system indicating severity as follows: no prolapse, 0; mild, 1; moderate, 2; or severe, 3. A comparison between sequences on a per-patient basis was performed using a Wilcoxon's analysis with p < 0.05 considered significant. RESULTS. Overall, 66.1% (39/59) of patients had more severe prolapse (>= 1 degrees) based on dynamic true FISP images, with 28.8% (17/59) of the cases of prolapse seen exclusively on true FISP images. Only 20.3% (12/59) of patients had greater degrees of prolapse on HASTE images than on true FISP images, with 10.2% (6/59) of the cases seen exclusively on HASTE images. A statistically significant increase in the severity of cystoceles (p < 0.01) and urethral hypermobility (p < 0.01)-with a trend toward more severe urethroceles (p < 0.07), vaginal prolapse (p < 0.09), and rectal descent (p < 0.06)-was shown on true FISP images. CONCLUSION. Overall, greater degrees of organ prolapse in all three compartments were found with a dynamic true FISP sequence compared with a sequential HASTE sequence. Near real-time continuous imaging with a dynamic true FISP sequence should be included in MR protocols to evaluate pelvic floor dysfunction in addition to dynamic multiplanar HASTE sequences.