Brachial Plexus Contouring with CT and MR Imaging in Radiation Therapy Planning for Head and Neck Cancer1.
Summary of "Brachial Plexus Contouring with CT and MR Imaging in Radiation Therapy Planning for Head and Neck Cancer1."
With the increasing use of intensity-modulated radiation therapy (IMRT) for the treatment of head and neck cancer, radiation oncologists are expected to have an in-depth knowledge of the computed tomographic (CT) and magnetic resonance (MR) imaging anatomy of this region to be able to accurately characterize tumor extent and define organs at risk for potential radiation injury. The brachial plexus is a complex anatomic structure in the head and neck adjacent to diseased nodes and elective nodal volumes (ie, nodal areas that are prophylactically treated because they are at high risk for micrometastatic disease) and should, therefore, be carefully identified and contoured at CT prior to IMRT planning. A number of multi-institutional protocols mandate contouring the brachial plexus as an "avoidance structure" (ie, a structure or volume that is at risk for complications of radiation therapy) in the planning of head and neck radiation therapy, and, although little information exists on the best method of doing so consistently, contouring may be facilitated with fusion CT-MR imaging software. With three-dimensional conformal radiation therapy, the brachial plexus is not routinely contoured; therefore, its dose limits are not evaluated in treatment planning. In contrast, with IMRT, tolerance doses can be set to limit the maximum dose to the brachial plexus to 60 Gy in most radiation protocols, although the true radiation tolerance dose in patients with head and neck cancer has been mentioned only sporadically in the literature. Additional studies will be required to determine if identification of the brachial plexus as an avoidance structure prior to radiation therapy planning improves treatment outcome in patients with head and neck cancer and reduces long-term toxicity in this structure.
Affiliation
Departments of Radiation Oncology and Radiology, Boston Medical Center, Boston University School of Medicine, 830 Harrison Ave, Moakley Building LL 238, Boston, MA 02118.
Journal Details
This article was published in the following journal.
Name: Radiographics : a review publication of the Radiological Society of North America, Inc
ISSN: 1527-1323
Pages: 1095-103
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20631370
- DOI: http://dx.doi.org/10.1148/rg.304095105
Medical and Biotech [MESH] Definitions
Brachial Plexus Neuritis
A syndrome associated with inflammation of the BRACHIAL PLEXUS. Clinical features include severe pain in the shoulder region which may be accompanied by MUSCLE WEAKNESS and loss of sensation in the upper extremity. This condition may be associated with VIRUS DISEASES; IMMUNIZATION; SURGERY; heroin use (see HEROIN DEPENDENCE); and other conditions. The term brachial neuralgia generally refers to pain associated with brachial plexus injury. (From Adams et al., Principles of Neurology, 6th ed, pp1355-6)
Brachial Plexus
The large network of nerve fibers which distributes the innervation of the upper extremity. The brachial plexus extends from the neck into the axilla. In humans, the nerves of the plexus usually originate from the lower cervical and the first thoracic spinal cord segments (C5-C8 and T1), but variations are not uncommon.
Brachial Plexus Neuropathies
Diseases of the cervical (and first thoracic) roots, nerve trunks, cords, and peripheral nerve components of the BRACHIAL PLEXUS. Clinical manifestations include regional pain, PARESTHESIA; MUSCLE WEAKNESS, and decreased sensation (HYPESTHESIA) in the upper extremity. These disorders may be associated with trauma (including BIRTH INJURIES); THORACIC OUTLET SYNDROME; NEOPLASMS; NEURITIS; RADIOTHERAPY; and other conditions. (From Adams et al., Principles of Neurology, 6th ed, pp1351-2)
Cervical Rib Syndrome
A condition associated with compression of the BRACHIAL PLEXUS; SUBCLAVIAN ARTERY; and SUBCLAVIAN VEIN at the thoracic outlet and caused by a complete or incomplete anomalous CERVICAL RIB or fascial band connecting the tip of a cervical rib with the first thoracic rib. Clinical manifestations may include pain in the neck and shoulder which radiates into the upper extremity, PARESIS or PARALYSIS of brachial plexus innervated muscles; sensory loss; PARESTHESIAS; ISCHEMIA; and EDEMA. (Adams et al., Principles of Neurology, 6th ed, p214)
Thoracic Outlet Syndrome
A neurovascular syndrome associated with compression of the BRACHIAL PLEXUS; SUBCLAVIAN ARTERY; and SUBCLAVIAN VEIN at the superior thoracic outlet. This may result from a variety of anomalies such as a CERVICAL RIB, anomalous fascial bands, and abnormalities of the origin or insertion of the anterior or medial scalene muscles. Clinical features may include pain in the shoulder and neck region which radiates into the arm, PARESIS or PARALYSIS of brachial plexus innervated muscles, PARESTHESIA, loss of sensation, reduction of arterial pulses in the affected extremity, ISCHEMIA, and EDEMA. (Adams et al., Principles of Neurology, 6th ed, pp214-5).
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