Role of Imaging in Cancer Treatment

Abstract

Cancer therapy and cancer imaging are scientific and clinical companions. Most cancers are initially detected by an imaging technique, either through the routine screening of at-risk populations or by the evaluation of patients presenting with symptoms. Imaging the human body began as part of routine clinical care with the development of X-ray imaging by Roentgen. While X-rays still play an important role in cancer evaluation, the imaging technologies have expanded greatly over the past 30 years. Computerized tomographic (CT) imaging has added immeasurably to the clinician’s ability to find, measure, and monitor cancers. The algorithms originally developed by Hounsfield to produce tomographic images with X-rays have also been extended to nuclear medicine for use with positron emission tomography (PET) and single photon emission computed tomography (SPECT). The development of magnetic resonance imaging (MRI) has provided high levels of contrast with superb resolution in many areas of the body. These techniques have been complemented by ultrasound (US) imaging and more recently by the introduction of new optical approaches. Each technique has its strengths and limitations, leading clinicians to compare the results and data from the various approaches to determine the optimal imaging modalities to use for a given indication. Clinical presentation often leads a physician to obtain a series of images as an evaluation progresses or changes. For example, one might initially detect a suspicious lesion with a simple chest X-ray, more completely evaluate its characteristics and extent with a CT scan, and use PET to help stage the tumor within the thorax and abdomen or MRI to detect lesions within the brain. In fact, new devices are beginning to combine modalities, such as PET and CT, to take advantage of the strengths of each approach (Fig. 1)

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