Aqueductal flow of cerebrospinal fluid (CSF) and anatomical configuration of the cerebral aqueduct (AC) in patients with communicating hydrocephalus--the trumpet sign

Purpose: We explore the relationship of aqueductal flow of cerebrospinal fluid (CSF) and the changes of the anatomical configuration of the cerebral aqueduct (AC) in patients with communicating hydrocephalus (CH) in a routine MRI setting.

Methods/patients: We performed a retrospective evaluation of different anatomical configurations of the AC on midsaggital MRI images in 43 patients (medial age 67 years, median 68 years, range from 14 to 85, 25 women) with suspected communicating hydrocephalus and compared the anatomical form of the AC on the sagittal sequences with MRI CSF flow data. The measured acqueductal cross sectional area was correlated (Pearson's correlation coefficient, which is a measure of the linear dependence between two variables, is 0.747. From 0.7 to 1 correlation is strong, from 0.7 to 0.5 moderate correlation, from 0.5 to 0.3 weak correlation, and 0.3 to 0 means no correlation) with MRI CSF flow data based on phase contrast measurements.

Results: Two independent neuroradiologists were blinded to the patients' diagnosis. In 53% (Rater I) and 67% (Rater II) the anatomical appearance of the AC on sagittal MRI was tubular shaped and in 47% (Rater I) and 33% (Rater II) trumpet shaped. Highly elevated CSF flow correlated with a dilated and trumpet shaped AC lumen area.

Conclusion: The anatomical morphology of the AC in midsagittal MRI sequences may be a significant diagnostic sign for suspected communicating hydrocephalus, already discernible on routine MRI scans; consequently, this may also be a sensitive method of supporting the clinical diagnosis of communicating hydrocephalus and moreover supports patients' selection for further CSF flow measurements.