AJNR Blog » diffusion study; Echo-Planar Imaging

educational presentation: atypical features in pres

MCastillo — Mon, 07 Jun 2010 17:24:37 +0000

Here is another presentation that I hope our readers and visitors will find useful and enjoy. We presented this as an “exhibit” at the past meeting of ASNR. The presentation deals with atypical MRI findings in posterior reversible encephalopathy syndrome.

educational presentation: DWI of brain abscesses

MCastillo — Fri, 04 Dec 2009 18:08:44 +0000

abscesses dwi

We are back from RSNA and it is time to post a new educational activity in our blog. This presentation, by one of our previous neuroradiology fellows, addresses the typical and atypical findings and utility of DWI in the evaluation of brain abscesses.

ADC question

nbargallo — Tue, 24 Mar 2009 22:32:12 +0000

I will like to know if someone can help me with some doubts I have regarding ADCs.

1. I have a sample with some ADC values obtained in 1,5 T and others obtained in 3T ( same b value). Can I use the ADC values for statistics or do you think that they cannot be compared?

2. Are the ADC values obtained using a diffusion sequence the same that the ADC values obtained in a DTI sequence with 12 directions?

Thank you in advance.

Distinguishing of Pleomorphic Adenomas From Other Types of Parotid Tumors by Diffusion-Weighted MR Imaging

hasanyerli — Tue, 03 Feb 2009 18:17:41 +0000

Until now, many articles have been published to declare that apparent diffusion coeficient calculation (ADC) by diffusion-weighted imaging (DWI) is a helpful method for differantiating malignant from benign parotid gland tumors. Habermann et al. in 2005 described that diffusion-weighted echo-planar MRI seems to be a valuable tool for differentiating benign from malignant primary parotid gland tumors in fifty consecutive patients (1). We read with interest the recent article of the same group in the January 2009 issue of the AJNR (2). The authors reached one different conclusion in one hundred thirty-six patients with parotid tumors. They claimed that, DWI has the potential to differentiate only pleomorphic adenoma and myoepithelial adenomas from other parotid tumor types and state that “…in contrast to most other studies, an overlap regarding the ADC values from Warthin tumors and three different malignant subtypes of parotid gland lesions…” is present.

We would like to draw the authors’ attention to our report that is previously published in 2007 (3). We had already determined that DWI appears to be useful for distinguishing pleomorphic adenomas from other types of parotid gland tumors and calculating ADC values did not help to differentiate Warthin tumors from malignant parotid tumors. We are pleased that the good designed study with large patient population by Habermann and coworkers supports our results.

In our experience, morphologic criteria such as irreguler border, invasion of the mass and heterogeneous hypointense signals on T2-weighted images are still valuable in diagnosing malignant parotid tumors.

References

Habermann CR, Gossrau P, Graessner J, et al. Diffusion-weighted echo-planar MRI: a valuable tool for differentiating primary parotid gland tumors? Rofo 2005;177:940-5.
Habermann CR, Arndt C, Graessner J. Diffusion-Weighted Echo-Planar MR Imaging of Primary Parotid Gland Tumors: Is a Prediction of Different Histologic Subtypes Possible? AJNR Am J Neuroradiol published 8 January 2009, 10.3174/AJNR.A1412
Yerli H, Agildere AM, Aydin E, et al. Value of apparent diffusion coefficient calculation in the differential diagnosis of parotid gland tumors. Acta Radiol 2007; 48: 980-7.