The Role of Diffusion-Weighted Magnetic Resonance Imaging in Cholesteatoma Diagnosis and Follow-up: Study With the Diffusion PROPELLER Technique

Influence of blade width and magnetic field strength on the ADC on PROPELLER DWI in head and neck

PURPOSE

The purpose of this study was to investigate the influence of blade width and magnetic field strength on apparent diffusion coefficient values of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging in the head and neck at 1.5 and 3.0 T magnetic resonance imaging.

METHODS

Fifteen healthy volunteers (eight men and seven women; mean age 36.4 ± 10.1 years) underwent PROPELLER diffusion-weighted imaging using four blade widths at 3.0 T and three blade widths at 1.5 T. For the multigroup comparison of apparent diffusion coefficient values, we performed analysis of variance and Tukey-Kramer tests. The apparent diffusion coefficient values in each organ were compared among the different blade widths and magnetic field strengths by a t test. Inter and intra-observer agreements regarding apparent diffusion coefficient value measurements were evaluated using the intraclass correlation coefficient.

RESULTS

No significant differences were observed in apparent diffusion coefficient values of the cerebellum in each blade width at both field strengths. The apparent diffusion coefficient values of the right parotid glands were significantly lower for blade width 32 than for blade width 16 at 3.0 T (1.16 × 10^-3 mm²/s vs. 1.01 × 10^-3 mm²/s; P < 0.05). The apparent diffusion coefficient values of bilateral parotid glands were significantly higher at 1.5 T than at 3.0 T. Intraclass correlation coefficients were almost perfect to substantial in the cerebellum, whereas they showed moderate agreement in the parotid glands.

CONCLUSION

The largest blade width 32 at 3.0 T and high magnetic field strength lowered the apparent diffusion coefficient values of parotid glands of PROPELLER diffusion-weighted imaging. The apparent diffusion coefficient values in the parotid glands of PROPELLER diffusion-weighted imaging may be affected for blade width and magnetic field strength.

Diffusion-Weighted Magnetic Resonance Imaging of Cholesteatoma Using PROPELLER at 1.5T: A Single-Centre Retrospective Study

PURPOSE

The purpose of this study was to evaluate the sensitivity, specificity, and positive and negative predictive values of the diffusion-weighted periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique in the detection of cholesteatoma at our institution with surgical confirmation in all cases.

METHODS

A retrospective review of 21 consecutive patients who underwent diffusion-weighted PROPELLER magnetic resonance imaging (MRI) on a 1.5T MRI scanner prior to primary or revision/second-look surgery for suspected cholesteatoma from 2009-2012 was performed.

RESULTS

Diffusion-weighted PROPELLER had a sensitivity of 75%, specificity of 60%, positive predictive value of 86%, and negative predictive value of 43%. In the 15 patients for whom the presence or absence of cholesteatoma was correctly predicted, there were 2 cases where the reported locations of diffusion restriction did not correspond to the location of the cholesteatoma observed at surgery.

CONCLUSION

On the basis of our retrospective study, we conclude that diffusion-weighted PROPELLER MRI is not sufficiently accurate to replace second look surgery at our institution.