Imaging is a key service required for the delivery of cancer care, from obtaining a diagnosis, to determining the extent of disease, assessing response to treatments, detecting recurrent disease and the use of interventional approaches (Table 17.1). It is important to consider whether a particular test will influence the management of a patient and this should be balanced against the potential harm of exposure to ionising radiation used in some forms of imaging.
Plain film imaging
Plain films are particularly useful for imaging the skeleton. They can demonstrate sclerotic and lytic bone reactions due to metastasis and provide information about the likelihood for an impending fracture due to metastatic disease. A chest X-ray is a simple means of screening for metastasis to the lungs and for suspected infection.
Plain film imaging is used for mammographic screening of women for breast cancer. This is a radiological investigation for lumps and microcalcifications. Both invasive cancers and ductal carcinoma in situ can be detected using this imaging modality. Women testing positive are referred for assessment with clinical examination, ultrasound and FNA cytology. Mammography remains the only imaging method clearly proven effective when applied in the screening setting.
Ultrasound
Ultrasound imaging can be performed at the bedside. Through the use of high-frequency sound waves images can be obtained in many planes, but this is reliant on a skilled operator. The sound waves do not penetrate well into areas of gas or bone and are reflected, causing a ‘shadow effect’ behind the target area. The resolution is decreased by overlying fat.
Ultrasound has a clear role in screening for liver metastasis, in conjunction with clinical examination and serum biochemistry. Testicular masses can be demonstrated on ultrasound, which is effective in distinguishing cystic from solid carcinoma. This is useful when assessing thyroid, breast and particularly renal masses, where cysts can be distinguished from carcinoma in 90% of cases.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
