Chest imaging is a critical diagnostic tool for evaluating thoracic anomalies in anatomic structure and disease. The variety of imaging technologies available for diagnostic evaluation in the chest includes plain-film radiography, computed tomography (CT), positron-emission tomography (PET), concurrent PET/CT, and magnetic resonance imaging (MRI). These radiologic procedures are further enhanced by oral or intravenously administered contrast materials used alone or in combination. The role of radiologic imaging in thoracic surgery is likely to gain even more importance as imaging technologies provide ever more accurate means of visualization.
Patients often are referred to thoracic surgeons for evaluation and treatment of incidental findings on chest CT or radiography. These incidental findings can be fortuitous for the patient, providing the opportunity for treatment before the development of symptoms heralding advanced disease. The thoracic surgeon may choose to further the evaluation with registered PET/CT or to follow indeterminate findings over time with serial CT scans.
CT is the backbone imaging modality for preoperative evaluation. The adrenal glands are always included in routine chest CT images because this is a common site of lung cancer metastases. CT can be supplemented with PET/CT or MRI for special purposes. These modalities are often useful for problem solving. PET/CT has dramatically increased the ability of imaging to contribute to accurate preoperative staging in lung cancer, thereby setting patients on the proper treatment course from the outset. The resulting change in lung cancer staging flows from the ability of PET/CT both to recognize unsuspected distant metastases and to identify coexisting benign disease. For example, before the availability of PET/CT, inflammation in contralateral lymph nodes often was attributed erroneously to a tumor of more advanced stage and patients were not offered potentially curative resection. Adjuvant PET/CT can provide preoperative staging information capable of upstaging (30%) or downstaging (15%) disease in an individual patient.1 In the setting of heterogeneous disease, PET/CT can be used to select the “best” biopsy site, in turn decreasing the number of biopsy specimens required to definitively classify difficult-to-identify cancers such as diffuse malignant pleural mesothelioma.
MRI is less useful than PET/CT, particularly with the advent of multidetector CT scanners, which permit data to be acquired with voxels of equal dimension in all three planes, thus providing sagittal and coronal images with CT that were previously only possible with MRI. This is not to say that MRI is without advantages. MRI can sensitively differentiate tissues, including blood, by differentiating the various states of hemoglobin. In addition, fascial planes are more sharply delineated by MRI. However, MRI demonstrates calcification as a signal void and thus may be considered inferior to CT for detecting calcifications. The use of MRI for problem solving is more apt to reflect the problem under consideration than a standard approach, although standardized imaging generally is applicable for visualizing the complete thorax in patients with diffuse malignant pleural mesothelioma.
In other instances, the ...