MR imaging of infradiaphragmatic lymphadenopathy in children and adolescents with Hodgkin disease: comparison with lymphography and CT

A Comparison of Whole-Body MRI and CT for the Staging of Lymphoma

OBJECTIVE

Our objective was to compare whole-body MRI and CT for the staging of lymphoma.

CONCLUSION

Whole-body MRI represents an alternative to CT in the staging of lymphoma, with an ability to stage disease, identify lymph nodes greater than 1.2 cm, and the additional ability to evaluate for the presence or absence of disease spread to bone marrow. CT allows detection of more nodes (< 1.2 cm) than MRI but this does not alter tumor stage.

CT and MR imaging in Hodgkin's disease - present and future

Initial staging of Hodgkin's disease is crucial to determine the location and extent of disease, and is the hallmark for the choice of treatment. At present, the established radiological technique for staging Hodgkin's disease is computed tomography (CT). Modern multidetector row CT scanners allow fast imaging from the scull base to the groins during a single breath hold with a spatial resolution of approximately 1 mm. Both, nodal and extranodal involvement of Hodgkin's disease can be diagnosed with CT. Magnetic resonance (MR) imaging is another useful cross-sectional imaging modality for staging Hodgkin's disease. The development of fast MR imaging techniques has considerably reduced imaging time without compromising the quality of MR images. As a consequence, MR imaging is now considered to be as diagnostic as CT for staging Hodgkin's disease. The excellent soft-tissue contrast and the lack of exposure to ionizing radiation are the main advantages of MR imaging. For the detection of extranodal Hodgkin's disease, MR imaging is superior to assess involvement of the brain, the spinal cord and bone marrow; while CT allows excellent evaluation of lung disease. Common major problems in staging Hodgkin's disease are still the detection of nodal involvement in normal sized lymph nodes and residual tumor masses after therapy. In the future, newly developed lymphotropic contrast agents for MR imaging might be helpful to answer these questions.

PET imaging in pediatric Hodgkin's lymphoma

Advances in diagnostic imaging technology, especially functional imaging modalities like positron emission tomography (PET), have significantly influenced the staging and treatment approaches used for pediatric Hodgkin's lymphoma. Today, the majority of children and adolescents diagnosed with Hodgkin's lymphoma will be cured following treatment with non-cross-resistant combination chemotherapy alone or in combination with low-dose, involved-field radiation. This success produced a greater appreciation of long-term complications related to radiation, chemotherapy, and surgical staging that prompted significant changes in staging and treatment protocols for children and adolescents with Hodgkin's lymphoma. Contemporary treatment for pediatric Hodgkin's lymphoma uses a risk-adapted approach that reduces the number of combination chemotherapy cycles and radiation treatment fields and doses for patients with localized favorable disease presentation. Advances in diagnostic imaging technology have played a critical role in the development of these risk-adapted treatment regimens. The introduction of computed tomography (CT) provided an accurate and non-invasive modality to define nodal involvement below the diaphragm that motivated the change from surgical to clinical staging. The introduction of functional imaging modalities, like positron emission tomography (PET) scanning, provided the means to correlate tumor activity with anatomic features generated by CT and modify treatment based on tumor response. For centers with access to this modality, PET imaging plays an important role in staging, evaluating tumor response, planning radiation treatment fields, and monitoring after completion of therapy for pediatric Hodgkin's lymphoma. This trend will likely increase in the future as a result of PET's superior sensitivity in correlating sites of tumor activity compared to other available functional imaging modalities. Ongoing prospective studies of PET in pediatric patients will increase understanding about the optimal use of this modality in children with cancer and define the characteristics of FDG-avid nonmalignant conditions that may be problematic in the interpretation of tumor activity.

Hodgkin's disease

Despite incomplete understanding of the etiology of Hodgkin's disease and its malignant cell of origin, the majority of children and adolescents diagnosed with Hodgkin's disease will be longterm survivors. Staging and treatment for pediatric Hodgkin's disease has evolved over the past 30 years in attempts to reduce late treatment sequelae. Today, most children are clinically staged and treated with multitreatment chemotherapy, either alone or in conjunction with low-dose, involved field radiation therapy. Initial results with "risk-adapted" combined modality regimens limiting chemotherapy cycles and radiation doses and volumes demonstrate maintenance of cure rates for early stage, favorable Hodgkin's disease. Challenges for the future include identification of prognostic factors in patients at risk for treatment failure who may benefit from intensification of therapy.