Lymphoma: Characterization of Cervical Lymph Node Lesions with Simultaneous PET and MR
Partha Ghosh, MD
Case study data provided by Technical University of Munich, Munich, Germany
A patient presented with gradual and progressive swelling in the left side of the neck which on clinical examination appeared to be enlarged matted lymph nodes. Lymph node biopsy was suggestive of Hodgkin lymphoma. A simultaneous PET/MR study combining Fludeoxyglucose F 18* (18F FDG) PET and whole-body MRI was performed as part of the initial staging. Apart from 3D Dixon sequences for attenuation correction, STIR (fat suppression) and T1 sequences were performed for the whole-body scan.
*Siemens’ PETNET Solutions is a manufacturer of fludeoxyglucose F 18 injection (18F FDG). Indication and important safety information as approved by the US Food and Drug Administration can be found at the bottom of the page for 18F FDG, adult dose 5-10 mCi, administered by intravenous injection.
The images from simultaneous PET/MR show a grossly enlarged FDG-avid lymph node mass in the left upper deep cervical nodal group. There is also a solitary slightly enlarged FDG-avid lymph node on the same level on the right side suggestive of lymphomatous involvement in a single node on the right upper deep cervical chain. The axial fat suppressed MR image shows high signal intensity in the enlarged left-side lymph nodal mass (red arrow) as well as the solitary enlarged right-sided lymph node with corresponding high FDG uptake (red arrow). MR however shows a borderline enlarged lymph node just lateral to the FDG-avid right cervical node, which is hyperintense on STIR images. As depicted in the fused PET and MR images, the smaller right neck node (green arrow) does not show high FDG uptake and consequently was not considered to be involved with lymphoma.
Although fat suppression MR is highly sensitive for demonstration of lymph nodes, the main determinant of malignancy on morphological images alone is the nodal size. A combination of metabolic imaging with PET and morphological imaging like MRI (with enhanced detectability of lymph nodes due to fat suppression imaging and excellent soft tissue contrast) may help characterize normal as well as enlarged nodes, identify normal sized malignant nodes and distinguish benign nodal hyperplasia from malignant involvement. As shown in this example, simultaneous PET and MR acquisition ensures exact co-registration and absence of artifacts related to motion or swallowing as well as combines multiple soft tissue contrasts of MR with metabolic imaging of PET.
*Fludeoxyglucose F 18 Injection
INDICATIONS AND USAGE
Fludeoxyglucose F 18 injection (18F FDG) is indicated for positron emission tomography (PET) imaging in the following setting:
Oncology: For assessment of abnormal glucose metabolism to assist in the evaluation of malignancy in patients with known or suspected abnormalities found by other testing modalities, or in patients with an existing diagnosis of cancer.
IMPORTANT SAFETY INFORMATION
Radiation-emitting products, including fludeoxyglucose F 18 injection, may increase the risk for cancer, especially in pediatric patients. Use the smallest dose necessary for imaging and ensure safe handling to protect the patient and health care worker.
Blood Glucose Abnormalities
In the oncology and neurology setting, suboptimal imaging may occur in patients with inadequately regulated blood glucose levels. In these patients, consider medical therapy and laboratory testing to assure at least two days of normoglycemia prior to fludeoxyglucose F18 injection administration.
Hypersensitivity reactions with pruritus, edema and rash have been reported; have emergency resuscitation equipment and personnel immediately available.
Fludeoxyglucose F 18 injection is manufactured by Siemens' PETNET Solutions, 810 Innovation Drive, Knoxville, TN 39732
The statements by Siemens customers described herein are based on results that were achieved in the customer's unique setting. Since there is no "typical" hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.