![]() ![]() Even if there are residual masses, a complete metabolic response is considered a complete remission of lymphoma. Uptake “markedly” higher than liver or new lesionsįor most clinical situations, a 5PS of 1, 2, or 3 represents a complete metabolic response, without evidence of residual active lymphoma ( Figs. Uptake greater than mediastinal background but less than or equal to liver background ![]() Uptake less than or equal to mediastinal background The 5PS scores the greatest residual FDG avidity at a site of initial disease as follows: A five-point scale (5PS) is described in the Lugano Classification, which provides high interobserver assessment of lymphoma treatment response. Only the central nervous system is described to be best evaluated by another imaging modality, MR, rather than FDG PET/CT.įollowing treatment, FDG PET/CT is more accurate in determining treatment response than is CT for FDG-avid lymphomas. Splenic, liver, and other organ involvement is also best evaluated by FDG PET/CT, despite physiologic activity in some organs. Evaluation of the osseous structures on FDG PET/CT is so sensitive for bone marrow involvement that routine bone marrow biopsy is no longer indicated for most patients with HL and DLBCL. Conversely, homogenous elevation of FDG avidity in the bone marrow is usually bone marrow repopulation (see Chapter 3, Fig. FDG PET/CT can identify if there are any lesions of high FDG avidity, suspicious for transformation, that have developed and can direct biopsy to an accessible highly FDG-avid lesion.įocal FDG avidity within the bone or bone marrow is highly sensitive for osseous lymphoma in FDG-avid lymphomas. This is valuable for patients for whom malignant transformation from a low-grade lymphoma to a more aggressive high-grade lymphoma is suspected. Values between 10 and 20 are usually high-grade lymphomas, but there is some overlap. 13.2 ), whereas SUV less than 10 is typically a low-grade lymphoma (see Chapter 13, Fig. As a rule of thumb, a pretreatment SUV of greater than 20 indicates high-grade lymphoma (see Chapter 13, Fig. However, after lymphoma has been diagnosed by biopsy, the SUVmax can be used to help distinguish low-grade from high-grade lymphoma. The intensity of FDG avidity (the standardized uptake value max of the node) cannot be used to diagnosis lymphoma in lieu of a biopsy. A biopsy is needed to confirm that FDG-avid nodes represent lymphoma. These consensus guidelines state that FDG PET/CT should be recommended for the initial staging of FDG-avid nodal lymphomas. These guidelines were produced following an International Conference on Malignant Lymphoma held in Lugano, Switzerland. The most recent recommendations for the use of FDG PET/CT are referred to as the Lugano Classification. In non–FDG avid lymphomas, contrast-enhanced CT is the standard imaging modality. FDG PET/CT would be useful in these lymphomas only if the tumor in an individual patient was proven to be FDG avid. Some lymphomas have variable FDG avidity, including chronic lymphocytic leukemia/small lymphocytic lymphoma, lymphoplasmacytic lymphoma, and marginal zone lymphoma. The vast majority of lymphomas are FDG avid, including the most common lymphomas, Hodgkin lymphoma (HL), diffuse large B-cell lymphoma(DLBCL), and follicular lymphoma. FDG PET/CT has become the primary imaging modality for staging and treatment response in patients with FDG-avid lymphomas. ![]()
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