Here are 2 different patients with similar findings. The top image is a diffusion weighted body MRI in a patient with liver metastases from breast cancer. The patients bone marrow is dark on this negative image indicating restricted diffusion. Restricted diffusion occurs in regions of increased cellular density. The second (middle) image is a whole body PET/CT in a patient with lymphoma. A pre chemo PET/CT is displayed above a post chemo PET/CT. Note the diffusely increased FDG uptake in the marrow space indicating increased glucose metabolism. Note also a significant response to therapy. The patients were both receiving GCSF which increases Bone marrow cellular density and metabolism.

PET FDG: Bladder Cancer with Nodal Mets.

Patient with Bladder Ca post surgical resection with recurrent disease in a left obturator lymph node.

Although limited by the normally excreated FDG in the bladder, FDG PET may have some use for staging in bladder cancer. FDG PET is not sensitive enough to be used in the detection of primary, low-stage bladder cancers. PET may be useful, in conjunction with conventional studies, in staging locally extensive lesions. It helps identify lymph node and distant metastases and in differentiating recurrent disease from tissue changes following surgery and radiation. Diuresis or irrigation of the bladder with saline increase the sensitivity of PET FDG for local tumors and node detection.