Integrating PET and PET/CT into the Risk-Adapted Therapy of Lymphoma
Yvette L. Kasamon1,2,
Richard J. Jones1 and
Richard L. Wahl1,3
1 Department of Oncology, Johns Hopkins Medical Institutions, Baltimore, Maryland; 2 Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland; and 3 Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
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FIGURE 1. PET/CT for staging of Hodgkin's lymphoma. CT showed involvement only in right neck. PET/CT (A: coronal views; B: transverse views; MIP = maximum-intensity projection) showed that normal-size (9-mm) upper mediastinal lymph node was clearly metabolically active, changing stage from I to II. This finding is relevant if consolidative radiation after chemotherapy is planned. Incidental normal scalene muscle uptake was noted on coronal PET.
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FIGURE 2. Defining positive PET results after treatment. After 3 cycles of chemotherapy for NHL, midtreatment PET/CT showed persistent, metabolically active disease in mediastinum (enhancing rim with central necrosis [arrow] in A; nodular pattern in B). After BMT in clinical trial, PET/CT showed decreased but persistent metabolic activity (C) compatible with either inflammation or residual malignancy, raising questions about management and prognosis. Uptake was in location of prior residual mass and was cephalad and distinct from thymus.
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FIGURE 3. PET/CT for early risk stratification. Midtreatment PET/CT after 3 cycles of chemotherapy for diffuse large B-cell lymphoma showed dramatic anatomic response (baseline imaging not shown) but persistent metabolic activity in multiple mediastinal and para-aortic lymph nodes. Despite modification of chemotherapy in clinical trial, 2 mo later patient developed abdominal pain and was found to have fulminant disease progression (not shown). MIP = maximum-intensity projection.
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FIGURE 4. Kinetics of tumor cell killing and relationship to PET. Line B represents minimum rate of tumor cell killing that would lead to cure. Line A represents even more brisk tumor response that would produce cure after only 4 cycles of chemotherapy. Both of these lines would be associated with negative PET scan results after 2 cycles of chemotherapy. In contrast, line C represents rate of tumor cell killing that would be associated with negative PET scan results after 4–6 cycles of chemotherapy but would not produce cure. Importantly, PET scan results for line C would be positive after 2 or 3 cycles.
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FIGURE 5. PET/CT for monitoring response and remission status. After 4 cycles of chemotherapy for peripheral T-cell lymphoma (baseline imaging not shown), PET/CT (A) was negative for active disease, and patient completed 2 more cycles. Two months after therapy completion, worrisome symptoms developed, and PET/CT (B) showed multiple 18F-FDG–avid lymph nodes above and below diaphragm. CT at that time was not definitively abnormal but at 2 mo later showed definitive tumor progression. This case indicates that negative PET after treatment does not mean absence of active tumor and also indicates how PET/CT can be more sensitive than CT for detecting early recurrence. MIP = maximum-intensity projection.
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Copyright © 2007 by the Society of Nuclear Medicine.
