LUNG NODULE CT PET FUSION

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Figure 1a

History: CT examination of the chest (Figure 1a) on an 86-year-old male showed a right lung nodule. The patient was referred to Main Street Radiology for a whole body PET scan.


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Figure 1b

Findings: A hypermetabolic focus is seen within the right lower lobe on the axial PET image of the chest (Figure 1b) corresponding to the CT finding, compatible with carcinoma. CT-PET fusion image (Figure 1c) shows CT anatomical correlation of the functional PET finding. Axial PET image of the upper abdomen (Figure 2b) along with the CT-PET fusion image (Figure 2c) show abnormal activity within the liver and spine (arrows), compatible with metastatic disease, which are not appreciated on the CT exam (Figure 2a).


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Figure 1c

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Figure 2a

Discussion: PET is a functional imaging study, which exploits the hypermetabolic activity of cancers, manifested by increase uptake of a radioactive glucose analogue. However, since most normal tissues demonstrate far less activity, anatomical detail is limited. Correlation with a CT scan is often helpful to localize the exact location of PET scan abnormalities. While side-to-side comparison of PET and CT scan is usually sufficient, "fusion" of the two studies into a single set of images can be helpful. At Main Street Radiology, we have acquired CT-PET fusion software. When a CT scan is performed at MSR, the data can be "fused" with the corresponding PET scan.


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Figure 2b

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Figure 2c