FDG-PET accurate for staging of pediatric Hodgkin’s lymphoma
MedWire News: [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is a sensitive and specific test to detect bone marrow involvement in children and adolescents with Hodgkin's lymphoma, research shows.
FDG-PET imaging "may safely be substituted for a bone marrow biopsy in routine staging procedures," say Sandra Purz (University of Leipzig, Germany) and colleagues in the Journal of Clinical Oncology.
Bone marrow involvement in pediatric Hodgkin's lymphoma is assessed with a routine bone marrow biopsy. The biopsy, an invasive staging procedure, is important in clinical practice because the detection of bone marrow involvement confirms stage IV disease.
The patients with advanced disease can then be stratified into an intense treatment group.
However, the staging of Hodgkin's lymphoma has changed over time, as computed tomography (CT) and magnetic resonance imaging (MRI) are used more frequently since the imaging techniques have become more refined. FDG-PET is also used to detect bone marrow involvement in pediatric Hodgkin's lymphoma stage greater than IIA.
In this study, Purz and colleagues sought to define the value of FDG-PET to detect bone marrow involvement in 175 children with newly diagnosed classical Hodgkin's lymphoma. The initial staging of disease was determined using bone marrow biopsy, FDG-PET, and CT or MRI of the neck, abdomen, and pelvis.
Bone marrow biopsy results were positive in seven (4%) of the 175 patients, and these were also identified as having bone involvement by FDG-PET. Of the 168 bone-marrow-biopsy negative patients, FDG-PET results were negative in 127 patients and "questionable" in three patients.
FDG-PET scans showed bone marrow involvement in 45 patients: of these only seven were bone-marrow-biopsy positive. The specificity and positive predictive value of FDG-PET for the diagnosis of bone marrow involvement were 98.5% and 95.6%, respectively.
The researchers note that lesions in 32 of the 45 patients had the typical multifocal pattern and that the majority of the skeletal lesions disappeared after chemotherapy.
"Therefore, an adequate response to chemotherapy is an additional parameter to aid in the assessment of FDG-PET-positive bone marrow lesions," write Purz and colleagues.
The patients with a multifocal pattern presented with three or more lesions in the central part of the skeleton, including vertebrae, pelvis, chest, or proximal ends of humeri or femora.
The sensitivity of a bone marrow biopsy "appears compromised by the focal pattern of bone marrow involvement," add the investigators. The focal involvement pattern explains why untargeted bone marrow biopsies sampled from the iliac crest have low sensitivity, they suggest.
By MedWire Reporters