Objective: Our objective was to study the appearance of the uterus on MR images obtained during and 3 months after laser ablation of the endometrium and to determine if a correlation exists between the MR imaging findings and the subsequent clinical outcome. The appearance could then be used to guide the application of laser energy during the procedure to optimize the clinical result.
Subjects and methods: Eight women 34-55 years old (mean, 42 years old) with symptoms of heavy, painful menses underwent laser ablation under epidural anesthesia. Imaging was done on a 0.5-T Picker Asset system with a pelvic phased-array receiver coil using conventional T1-weighted spin-echo, T2-weighted spin-echo, and gradient-recalled-echo sequences. Images were obtained preoperatively, after ablation of the anterior surface, after completion of the procedure, and 3 months later. Images were visually assessed for signal intensity changes in the endometrium and myometrium by two observers in conference. Images were quantitatively analyzed by measuring uterine volume and the width of the endometrium, junctional zone (JZ), and outer myometrium (OM) on the T2-weighted images. Preoperative and 3-month postoperative symptom scores including duration, amount of bleeding, and associated pain were recorded.
Results: MR images obtained immediately after treatment showed an increase in the volume of the uterus (mean, 21%). Endometrial thickness increased in five patients, and the JZ:OM ratio increased on the T2-weighted scans in six patients. The increase in the ratio probably represented myometrial edema. Two patients with persistent symptoms were treated with hysterectomy 6 weeks postoperatively. Of the remaining six patients, five showed an improvement in symptom scores after 3 months. The uterus returned to its preoperative size after 3 months in three patients, endometrial thinning was noted in two, and the JZ:OM ratio remained increased in two. The difference between the mean improvement in symptom scores at 3 months was significant in the patients with and without the endometrial swelling seen immediately after treatment. No statistically significant correlation existed between the amount of perioperative uterine swelling or the increase in JZ:OM ratio and the improvement in symptom scores at 3 months.
Conclusion: On laser ablation of the endometrium, MR imaging showed significant immediate uterine swelling as well as an increase in the endometrial thickness and JZ:OM ratio. The presence of immediate endometrial swelling and the reduction in the JZ:OM ratio after 3 months correlated with a subsequent improvement in symptom scores. Perioperative endometrial swelling rather than myometrial changes is therefore an indicator of clinical outcome.