Quantitative assessment of dacryoscintigraphic images in the evaluation of epiphora.

Background: At the present time, only visual analysis is implemented on dacryoscintigraphic images and quantitative assessments are not routinely obtained. The authors have designed a novel, simple, quantitative method for the diagnosis of sac and post-sac obstructions based on the dacryoscintigraphic images.

Method: Fifty-nine patients with severe unilateral epiphora were included and the contralateral asymptomatic eyes were used as controls. After ocular instillation of 0.1 cc isotonic saline containing 4 MBq 99mTcO4, dynamic images were obtained for 20 minutes. Visual interpretation was done by two blinded specialists in nuclear medicine. A Time-Activity Curve (TAC) was generated for each eye and its pattern was divided to plateau type, shallow-down sloping and deep-down sloping. The excretion ratio (expressed as the percentage of drained activity) in the 2nd, 3rd, 5th, 7th, 10th, 15th and 20th minute of the study was calculated based on the following formula: (the total count in the region of interest (ROI) in the 1st minute - the total ROI count in the 2nd, 3rd, 5th, 7th, 10th, 15th or 20th minute/the total ROI count in the 1st minute) x 100. The results of the quantitative analysis were compared with the clinical symptoms, visual analysis and TAC pattern.

Results: At the optimal cut-off points for the 2nd, 3rd, 5th and 7th minute, the sensitivity of the prediction of obstruction was 76%, 72%, 71% and 69%, respectively. The correlation between visual interpretation and the TAC pattern was statistically significant.

Conclusion: The quantitative evaluation of dacryoscintigraphic images would contribute greatly to achieving an easier and more objective interpretation of the scintigraphic results and also provides a reliable tool for inter-individual comparison and the follow-up of patients. As it is the first time that this innovative method has been examined clinically, it will be necessary to investigate its clinical utility in a larger series of patients.