Image-guided Therapy of Skeletal Metastases
Image-guided Therapy of Skeletal Metastases
Response of skeletal lesions to treatment may result in reactive bone formation, or sclerosis. Sclerosis tends to progress from the periphery toward the center. Progressive sclerosis can make areas subtly more visible, giving a false impression of disease progression. Sclerosis of a lytic component usually suggests a positive response to treatment, while advanced or new lysis within a sclerotic or mixed area, or an increase in the size of a blastic lesion, may reflect actual disease progression. Determining response can be difficult as it is not always possible to differentiate residual tumor from the repair process. No consensus has been reached on the type of study to be used or the criteria to be applied for assessing response to treatment. Newer techniques are targeted at improving the distinction between viable tumor and necrotic tissue and the effects of treatment.
Scintigraphic uptake usually decreases following treatment. However, early in the course of treatment, particularly in patients receiving hormonal therapy, a flare phenomenon can occur. This is characterized by increase in uptake as a result of the stimulation of osteoblastic activity during the repair process.
Monitoring Treatment Response
Response of skeletal lesions to treatment may result in reactive bone formation, or sclerosis. Sclerosis tends to progress from the periphery toward the center. Progressive sclerosis can make areas subtly more visible, giving a false impression of disease progression. Sclerosis of a lytic component usually suggests a positive response to treatment, while advanced or new lysis within a sclerotic or mixed area, or an increase in the size of a blastic lesion, may reflect actual disease progression. Determining response can be difficult as it is not always possible to differentiate residual tumor from the repair process. No consensus has been reached on the type of study to be used or the criteria to be applied for assessing response to treatment. Newer techniques are targeted at improving the distinction between viable tumor and necrotic tissue and the effects of treatment.
Scintigraphic uptake usually decreases following treatment. However, early in the course of treatment, particularly in patients receiving hormonal therapy, a flare phenomenon can occur. This is characterized by increase in uptake as a result of the stimulation of osteoblastic activity during the repair process.
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