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Rofo 2005; 177(7): 940-945
DOI: 10.1055/s-2005-858297
Rapid Communication

© Georg Thieme Verlag KG Stuttgart · New York

Diffusion-Weighted Echo-Planar MRI: A Valuable Tool for Differentiating Primary Parotid Gland Tumors?

Diffusionsgewichtete MRT: Ist eine Differenzierung primärer Tumoren der Glandula parotidea möglich?C. R. Habermann1 , P. Gossrau1 , J. Graessner2 , C. Arndt1 , M. C. Cramer1 , F. Reitmeier3 , M. Jaehne3 , G. Adam1
  • 1Department of Diagnostic and Interventional Radiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany
  • 2Siemens AG, Medical Solutions, Hamburg, Germany
  • 3Department of Oto-, Rhino-, Laryngology, University Hospital Hamburg-Eppendorf, Hamburg, Germany
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Publication History

Publication Date:
22 June 2005 (online)

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Zusammenfassung

Ziel: Evaluation der diffusionsgewichteten (DW) echoplanaren (EPI) MRT zur Differenzierung verschiedener primärer Neoplasien der Glandula parotidea. Material und Methoden: Fünfzig Patienten mit Verdacht auf eine primäre Neoplasie der Glandula parotidea wurden mit einer DW-EPI-MR-Sequenz untersucht. Die angewandten b-Werte betrugen 0 sec/mm2, 500 sec/mm2 and 1000 sec/mm2. Die Signalintensitäten der ADC-(apparent-diffusion-coefficient-) Bilder wurden mit einer ROI (region of interest), welche den gesamten Tumor berücksichtigte, gemessen. Zusätzlich wurden die kontralaterale, nicht affektierte Drüse sowie der Liquor mittels ADC evaluiert. Für die statistische Auswertung wurde der zweiseitige Student’s-t-Test benutzt und ein p-Wert < 0,05 wurde als statistisch signifikant definiert. Ergebnisse: Bei 45 Patienten konnten sieben verschiedene Entitäten primärer Tumoren der Glandula parotidea histologisch nachgewiesen werden. Für das nicht tumorös affektierte Drüsengewebe wurde ein ADC-Wert von 1,14 × 10 - 3 mm2/sec ± 0,12 × 10 - 3 mm2/sec (Mittelwert ± Standardabweichung) gemessen. Pleomorphe Adenome (2,14 × 10 - 3 mm2/sec ± 0,11 × 10 - 3 mm2/sec) und Warthin-Tumoren (0,85 × 10 - 3 mm2/sec ± 0,1 × 10 - 3 mm2/sec), Lipome (0,35 × 10 - 3 mm2/sec ± 0,03 × 10 - 3 mm2/sec) und Mukoepiderxmoidkarzinome (1,04 × 10 - 3 mm2/sec ± 0,03 × 10 - 3 mm2/sec) konnten mit hoher statistischer Signifikanz (p ≤ 0,001) gegenüber sämtlichen anderen Entitäten abgegrenzt werden. Eine Differenzierung zwischen myoepithelialen Adenomen, Speichelgangkarzinomen und adenoidzystischen Karzinomen war mittels ADC nicht möglich (p = 0,8 bis 1). Schlussfolgerungen: Mittels diffusionsgewichteter echoplanarer MRT erscheint eine Differenzierung von bis zu 95 % der Tumoren der Ohrspeicheldrüsen möglich.

Abstract

Purpose: To investigate the feasibility of using diffusion-weighted (DW) echo-planar imaging (EPI) for differentiating primary parotid gland tumors. Material and Methods: Fifty consecutive patients with a suspected primary tumor of the parotid gland were examined with a DW EPI sequence (TR 1,500 msec, TE 77 msec, field of view 250 × 250 mm, pixel size 2.10 × 1.95 mm, section thickness 5 mm). The b factors used were 0, 500, and 1,000 sec/mm2. Apparent diffusion coefficient (ADC) maps were digitally transferred to MRIcro (Chris Rorden, University of Nottingham, Great Britain) and evaluated with a manually placed irregular region of interest (ROI) containing the entire tumor. Additionally, the contralateral, non affected parotid gland was measured and a circular ROI containing 100 - 200 pixels was placed in the cerebrospinal fluid (CSF) next to the spinal cord in every patient. For comparison of the results, the two-tailed Student’s t test was used, based on the median ADC values for each patient, and a p-value <.05 was determined to indicate statistical significance. Results: In 45 patients, a primary neoplasm of the parotid gland could be histologically verified. For the non-affected parotid glands of all 45 evaluated patients, the mean ADC value was 1.14 × 10 - 3 mm2/sec ± 0.12 × 10 - 3 mm2/sec (mean ± standard deviation). Seven different entities of parotid gland tumors were histologically discriminated. Pleomorphic adenomas (2.14 × 10 - 3 mm2/sec ± 0.11 × 10 - 3 mm2/sec), Warthin tumors (0.85 × 10 - 3 mm2/sec ± 0.1 × 10 - 3 mm2/sec), and mucoepidermoid carcinomas (1.04 × 10 - 3 mm2/sec ± 0.3 × 10 - 3 mm2/sec) showed statistically significant different ADC values in comparison to all other evaluated tumors (p .001), and also among each other (p <.001). Additionally, ADC values presented by lipomas were statistically significant compared to all other entities (p <.001 to .015). Among primary malignant parotid gland tumors, no statistically significant ADC values could be observed (p .18 to 1). Conclusion: Diffusion-weighted echo-planar MRI seems to be a valuable tool for differentiating benign from malignant primary parotid gland tumors.

Key words

Primary parotid gland tumors - MRI - diffusion-weighted (DW) echo-planar imaging (EPI) - apparent diffusion coefficient (ADC)

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Dr. Christian R. Habermann

Department of Diagnostic and Interventional Radiology, University Hospital Hamburg-Eppendorf

Martinistraße 52

20246 Hamburg

Phone: 040/4 28 03 40 10

Fax: 0 40/4 28 03 67 99

Email: c.habermann@uke.uni-hamburg.de

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