Lesions and nodes of the thoracic inlet.

The anatomy of the thoracic inlet and lesions of the thyroid gland, parathyroid glands, and brachial plexus are discussed in depth in other articles in this issue. The focus of this article is to review lesions of the remaining structures and spaces that abut or traverse through the plane of the thoracic inlet. Although this junction of the neck with the chest is relatively easy to define on coronal or sagittal MR, determining this level with axial CT and MR is actually a bit of a challenge. Depending on neck length, degree of neck extension, shoulder thickness, arm position, thoracic kyphosis, and scan angle, the appearance of this area is extremely variable. For the purpose of this article, the thoracic inlet is better regarded as a zone or volume extending several centimeters both above and below this plane. In addition, this zone is very prone to CT beam hardening artifacts from the thickness of the shoulders as well as MR pulsation, respiratory, and bulk susceptibility artifacts, often resulting in less than esthetic images.