Abstract
Purpose: To examine the variation in the anatomy of parotid glands discerned by magnetic resonance imaging. Methods: Head and neck magnetic resonance scans of 16 patients (representing 32 glands) whose studies consisted of 5 mm contiguous sections were selected at random. The T1 weighted scans were thresholded and outlined to only encompass the parotid tissue. A volumetric analysis program (ISG Technologies, Inc.) was used to compute the parotid volume in cubic millimeters. Each of the 32 glands was measured independently by two observers. Results: The difference between observers averaged 4.8%. The median volume was 25 262 mm3, range 9225-54 080 mm3. In four patients there were considerable differences in the volumes of the right and left parotid glands, with variations of 9, 10, 14 and 29%. In nine patients, (18 glands) the depth from the medial edge of the gland to the spinal cord ranged from 19-32 mm. However, the maximum variation between the two sides in a single patient was 4 mm. Observations made include: (1) parotid glands extending anterior to the masseter muscle, or posterior to the posterior margin of this muscle; (2) parotid glandular tissue extending above the zygoma and the external auditory canal; (3) parotid tissue extending posteriorly to overlap the spinal cord; (4) parotid glands extending below or remaining above the angle of the mandible; and (5) wide variation of the transverse dimension of the parotid glands, with one measuring 4.8 cm. Discussion: To ensure that the entire parotid is or is not in a treatment field a computerized tomography or magnetic resonance scan is necessary. If a specific portion of the gland must be in the field a volume histiogram must be available. Copyright (C) 2000 Elsevier Science Ireland Ltd.
Original language | English (US) |
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Pages (from-to) | 87-89 |
Number of pages | 3 |
Journal | Radiotherapy and Oncology |
Volume | 54 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 2000 |
Externally published | Yes |
Keywords
- Magnetic resonance imaging
- Parotid gland
- Parotid variations
- Radiation therapy
- Volume histogram
- Volumetric analysis
ASJC Scopus subject areas
- Hematology
- Oncology
- Radiology Nuclear Medicine and imaging