Christian R. Habermann MD, Presenter: Nothing to Disclose

Miriam C. Cramer MD, Abstract Co-Author: Nothing to Disclose

Joachim Graessner MS, Abstract Co-Author: Nothing to Disclose

Fabian Reitmeier, Abstract Co-Author: Nothing to Disclose

Michael Jaehne, Abstract Co-Author: Nothing to Disclose

Gerhard Adam, Abstract Co-Author: Nothing to Disclose

To investigate the feasibility of using diffusion-weighted (DW) echo-planar imaging (EPI) for measuring different functional conditions of the parotid gland and to compare different measurement approaches.

Parotid glands of 27 healthy volunteers were examined with a DW EPI sequence (TR 1,500 mses, TE 77 msec, field of view 250 x250 mm, pixel size 2.10 x 1.95 mm, section thickness 5 mm) with a 1.5 T imaging system before and after oral stimulation with commercially available lemon juice. The b factors used were 0, 500, and 1,000 sec/mm2. ADC maps were digitally transferred to MRIcro (Chris Rorden, University of Nottingham, Great Britain) and evaluated with a manually placed circular region of interest (ROI) containing 100-200 pixel. Additionally, ROIs including the entire parotid gland were placed on either side. The results of both measurements were compared. For comparison of the results, the Student’s t test was used, and a two-tailed P value of less than .05 was determined to indicate statistical significance. To compare both measurement approaches the Pearson’s correlation coefficient (r) was calculated.

Diffusion weighted echo-planar MR imaging successfully visualized the parotid glands of all volunteers. With use of ROIs containing 100-200 pixels, the median for both parotid glands prior to stimulation was 1.06 x 10-3 mm2/sec ± 0.07 x 10-3 mm2/sec. After stimulation, the median ADC for both parotid glands was measured at 1.15 x 10-3 mm2/sec ± 0.08 x 10-3 mm2/sec. For evaluating the entire parotid gland, the ADC prior to stimulation was 1.13 x 10-3 mm2/sec ± 0.05 x 10-3 mm2/sec, whereas after stimulation with lemon juice, the ADC increased to 1.22 x 10-3 mm2/sec ± 0.09 x 10-3 mm2/sec. For both measurement types, the increase in ADC after stimulation proved to be significant (P .83).

Diffusion-weighted echo-planar MR imaging allows quantifying functional changes in the parotid glands non-invasively. On this account, this technique could possibly replace salivary gland scintigraphy.

J.G.: Joachim Graessner is employee of Siemens Medical Services, Hamburg, Germany.

Habermann, C, Cramer, M, Graessner, J, Reitmeier, F, Jaehne, M, Adam, G, Functional Imaging of Parotid Glands: Diffusion-weighted Echo-planar MRI before and after Stimulation.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4405236.html