Imaging of extranodal lymphoma with PET/CT

Hodgkin disease (HD) and non-Hodgkin lymphoma (NHL) represent a spectrum of malignant neoplasms arising from the lymphoid system with an incidence of around 8% of all malignancies. Although they are generally known as tumors of lymph nodes, 25% to 40% of HD/NHL tumors, especially NHL, arise at extranodal sites along the gastrointestinal tract, head and neck, orbit, central and peripheral nervous system, thorax, bone, skin, breast, testis, thyroid, and genitourinary tract. Extranodal involvement is an important pretreatment prognostic factor for patients with lymphoma and its incidence has increased in the past 2 decades. Imaging plays an important role in the noninvasive pretreatment assessment of patients with extranodal lymphoma. This involvement can be subtle and may be overlooked during computed tomography (CT). Positron emission tomography/CT (PET/CT) has evolved into an important imaging tool for evaluation of lymphomas, facilitating the detection of affected extranodal sites even when CT shows subtle or no obvious lesions. Familiarity with extranodal manifestations and suggestive PET/CT features in different sites is important for accurate evaluation of lymphoma. This article reviews the extranodal PET/CT imaging findings regarding HD and NHL.     

Put your back into it: pathologic conditions of the spine at chest CT

It is common to encounter pathologic processes of the lower cervical, thoracic, or upper lumbar spine in the course of routine computed tomography (CT) of the chest. Although magnetic resonance (MR) is the imaging modality of choice for evaluating known spinal disease, evaluation of the spine is an integral part of interpreting a chest CT study. Spinal diseases often have a characteristic CT appearance that allows the radiologist to make the diagnosis or provide a structured differential diagnosis. Pathologic conditions of the spine that can be identified at chest CT are categorized into benign or incidental findings, congenital anomalies, traumatic injuries, infectious spondylitis, primary or secondary neoplastic involvement, and associations with systemic disease. CT also provides information about bone mineralization and lesion calcification that complements the superior soft-tissue imaging capability of MR. In addition, chest CT data may be reformatted to create volumetric or multiplanar images of the spine to facilitate management decisions about spinal stabilization in symptomatic patients.     

Imaging Hodgkin and non-Hodgkin lymphoma in the head and neck

Hodgkin (HL) and non-Hodgkin lymphoma (NHL) involving the head and neck have many overlapping imaging features. Definitive diagnosis depends on histology, but imaging trends may help distinguish lymphoma from other common pathologic entities in the head and neck. CT is useful for staging and assessing bony involvement, whereas MR imaging is performed for soft tissue detail in extranodal disease, especially when there is transpatial disease or intracranial or intraspinal extension. Positron emission tomography has become an important part of staging and surveillance imaging and is particularly useful to distinguish posttreatment fibrosis and residual tumor.     

The role of gallium-67 scan in defining the extent of disease in an endemic deep mycosis,paracoccidioidomycosis: a predominantly multifocal disease

The tools currently used to evaluate the extent of paracoccidioidomycosis (PCM) may be of limited value in detecting subclinical lesions. The aim of this study was to verify the role of gallium-67 whole-body scan in evaluating the extent of disease of 65 patients with active PCM. The (67)Ga scan findings were compared with the results of clinical evaluation, chest radiography and/or high-resolution computed tomography (CT), abdominal ultrasound (US) or CT, laryngoscopy, CT or magnetic resonance imaging (MRI) of the head, and technetium-99m methylene diphosphonate bone scan, obtained before treatment. Clinically unsuspected lesions were detected by imaging procedures in 21 patients (32%), mainly in the lungs (n=11), adrenals (n=6), and superficial (n=3) and deep lymph nodes (n=14). (67)Ga scan detected 100% of the cases with subclinical involvement in the lungs. Scintigraphy was superior to chest radiography in demonstrating lung disease (94% vs 81%). The lymphatic lesions were demonstrated by (67)Ga scan in all the clinically suspected cases and in nearly all unsuspected cases, and also revealed more extensive involvement than was clinically suspected in many of them. There was good agreement between (67)Ga scan and the other imaging procedures for the initial detection of thoracic and abdominal lymph nodes and bone involvement. (67)Ga imaging detected most cases of laryngopharyngeal disease with active inflammatory lesions found at indirect laryngoscopy. On the other hand, (67)Ga scan failed to demonstrate most of the adrenal and CNS lesions detected by abdominal US/CT and head CT/MRI. In conclusion, (67)Ga imaging is a useful tool for evaluating the location and extent of suspected and unsuspected lesions in PCM. It could serve as a screening method before the use of other diagnostic procedures, particularly in the detection of lung, superficial and deep lymph node and bone involvement.     

Fluorine-18 fluorodeoxyglucose positron emission tomography in the staging and follow-up of lymphoma: is it time to shift gears?

Positron emission tomography (PET) imaging has become a very useful technique for staging and monitoring therapy response in lymphoma, providing unique information about the biological behavior of disease. Increased fluorine-18 fluorodeoxyglucose (FDG) uptake in lymphoma is based on elevated glycolysis and longer residence time of FDG in malignant cells compared with most normal tissues. The metabolic information provided by this technique suggests that FDG-PET may be more sensitive than the anatomical imaging modalities. Computed tomography (CT) is the principal imaging modality for the staging and restaging of lymphoma. Nonetheless, this technique has significant shortcomings, particularly in the post-therapy setting. Gallium-67 scintigraphy has played an important role in monitoring response to therapy and follow-up of patients; however, the sensitivity of 67Ga depends on the subtype of lymphoma and the size and location of disease. Published results strongly indicate that FDG-PET is superior to 67Ga imaging and may be equal or superior to CT for the detection of nodal as well as extranodal involvement in lymphoma.     

MR evaluation of chest wall involvement in malignant lymphoma

Chest CT and magnetic resonance (MR) examinations of 28 patients with newly diagnosed or recurrent lymphoma involving the mediastinum were retrospectively evaluated for evidence of chest wall involvement. Computed tomography demonstrated seven sites of chest wall involvement in four patients; whereas MR demonstrated 14 sites in seven patients, including all sites shown by CT. Eight chest wall lesions were located in the extranodal soft tissues (three sites were contiguous with anterior mediastinal lymphadenopathy; three sites were contiguous with pleural/parenchymal disease; and one each involved the breast and multiple vertebral bodies). Six sites involved lymph nodes in the interpectoral (n = 4), submammary (n = 1), and infraspinatus (n = 1) areas. Lesion conspicuity in the chest wall was better on T2- than T1-weighted sequences and was best on short inversion time inversion recovery. Detection of chest wall lymphoma may alter staging; when present in this group of patients, it influenced management in two of the seven patients.     

Malignant pleural disease

The vast majority of pleural neoplasms invade the pleura secondarily and can be seen in patients with bronchogenic carcinoma, breast cancer, lymphoma, and ovarian or gastric carcinoma. Primary pleural neoplasms are less common, although they have developed notoriety since the up-surge of malignant mesothelioma and the knowledge of its connection to asbestos exposure. Other malignant primary tumors include localized fibrous tumor and pleural liposarcoma. In most patients with diffuse malignant pleural disease the chest radiograph shows pleural effusion with or without pleural thickening. Computed tomography (CT) usually provides precise localization and extent of the disease and may be of value in assessing chest wall and mediastinal involvement. In specific situations, magnetic resonance (MR) may be useful as a problem-solving tool when CT findings of chest wall or diaphragmatic invasion are equivocal or in patients with contraindication to intravenous administration of ionic contrast material.     

Staging of malignant lymphoma with three-station black-blood fast short-inversion time inversion recovery (STIR).

PURPOSE: The purpose of this study was to assess the usefulness of three-station black-blood fast short-inversion time inversion recovery (STIR) imaging in detecting and staging malignant lymphoma. METHODS: Seventeen patients with malignant lymphoma were examined with a 1.5T imager. The findings and stagings determined with three-station black-blood fast STIR imaging were compared with reference standards (e.g., computed tomography [CT] findings and clinical stagings). RESULTS: Three-station black-blood fast STIR imaging provided a fat-suppressed T2-weighted imaging contrast with fewer flow artifacts and revealed nodal involvement as well as bone marrow and spleen involvement to an extent comparable with CT. Especially notable was the excellent specificity (94%) of this imaging technique. Regarding disease staging, significant agreement was observed between clinical staging (k=0.60) and staging as evaluated by three-station black-blood fast STIR, although the detection of lymphadenopathy in the thorax was relatively poor. The average time required for this imaging was approximately 30 min. CONCLUSION: Three-station black-blood fast STIR MR imaging may be useful as a staging tool for malignant lymphoma because this imaging technique reveals lymphoma lesions, which determine the staging, without radiation exposure or the use of contrast agents.     

Hydatid disease: radiologic and pathologic features and complications.

Hydatid disease primarily affects the liver and typically demonstrates characteristic imaging findings. However, there are many potential local complications (eg, intrahepatic complications, exophytic growth, transdiaphragmatic thoracic involvement, perforation into hollow viscera, peritoneal seeding, biliary communication, portal vein involvement, abdominal wall invasion). Furthermore, secondary involvement due to hematogenous dissemination may be seen in almost any anatomic location (eg, lung, kidney, spleen, bone, brain). Ultrasonography (US) is particularly useful for the detection of cystic membranes, septa, and hydatid sand. Computed tomography (CT) best demonstrates cyst wall calcification and cyst infection. CT and magnetic resonance (MR) imaging may demonstrate cyst wall defects as well as the passage of contents through a defect. Chest radiography, US, CT, and MR imaging are all useful in depicting transdiaphragmatic migration of hydatid disease. CT is the modality of choice in peritoneal seeding. US and CT demonstrate rupture in most cases that involve wide communication. Indirect signs of biliary communication include increased echogenicity at US and fluid levels and signal intensity changes at MR imaging. CT allows precise assessment of osseous lesions, whereas MR imaging is superior in demonstrating neural involvement. Familiarity with atypical manifestations of hydatid disease may be helpful in making a prompt, accurate diagnosis.     

Fluorine-18 fluorodeoxyglucose positron emission tomography in the staging and follow-up of lymphoma: is it time to shift gears?

Positron emission tomography (PET) imaging has become a very useful technique for staging and monitoring therapy response in lymphoma, providing unique information about the biological behavior of disease. Increased fluorine-18 fluorodeoxyglucose (FDG) uptake in lymphoma is based on elevated glycolysis and longer residence time of FDG in malignant cells compared with most normal tissues. The metabolic information provided by this technique suggests that FDG-PET may be more sensitive than the anatomical imaging modalities. Computed tomography (CT) is the principal imaging modality for the staging and restaging of lymphoma. Nonetheless, this technique has significant shortcomings, particularly in the post-therapy setting. Gallium-67 scintigraphy has played an important role in monitoring response to therapy and follow-up of patients; however, the sensitivity of ⁶⁷Ga depends on the subtype of lymphoma and the size and location of disease. Published results strongly indicate that FDG-PET is superior to ⁶⁷Ga imaging and may be equal or superior to CT for the detection of nodal as well as extranodal involvement in lymphoma.     

Tumors of the osseous spine: staging with MR imaging versus CT

Twelve patients with tumors involving the osseous spine were evaluated with magnetic resonance (MR) imaging and computed tomography (CT), six with and six without intrathecal injection of contrast material. MR imaging was found to be superior to CT without contrast material and equal to CT with contrast material in delineating the anatomic relationships of the tumors, including bone involvement, spinal canal invasion, paraspinal soft-tissue extension, and vascular involvement. Since MR imaging can provide most of the anatomic information necessary for treatment planning, intrathecal injection of contrast material can be avoided in most instances when evaluating tumor involvement of the osseous spine. However, CT without contrast medium was superior to MR imaging in showing critical cortical bone destruction and calcified tumor matrix.     

Fluorine-18 fluorodeoxyglucose PET-CT for extranodal staging of non-Hodgkin and Hodgkin lymphoma

PURPOSE

We aimed to evaluate the role of fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸F-FDG PET-CT) involving care-dose unenhanced CT to detect extranodal involvement in patients with non-Hodgkin and Hodgkin lymphoma.

MATERIALS AND METHODS

Lymphoma patients (35 Hodgkin lymphoma, 75 non-Hodgkin lymphoma) who were referred for ¹⁸F-FDG PET-CT imaging, following a diagnostic contrast-enhanced CT (CE-CT) performed within the last month, were included in our study. A total of 129 PET-CT images, and all radiologic, clinical, and pathological records of these patients were retrospectively reviewed.

RESULTS

In total, 137 hypermetabolic extranodal infiltration sites were detected by ¹⁸F-FDG PET-CT in 62 of 110 patients. There were no positive findings by CE-CT that reflected organ involvement in 40 of 137 ¹⁸F-FDG-positive sites. The κ statistics revealed fair agreement between PET-CT and CE-CT for the detection of extranodal involvement (κ=0.60). The organs showing a disagreement between the two modalities were the spleen, bone marrow, bone, and thyroid and prostate glands. In all lesions that were negative at CE-CT, there was a diffuse ¹⁸F-FDG uptake pattern in the PET-CT images. The frequency of extranodal involvement was 51% and 58% in Hodgkin and non-Hodgkin lymphoma patients, respectively. There was a high positive correlation between the maximum standardized uptake values of the highest ¹⁸F-FDG-accumulating lymph nodes and extranodal sites (r=0.67) in patients with nodal and extranodal involvement.

CONCLUSION

¹⁸F-FDG PET-CT is a more effective technique than CE-CT for the evaluation of extranodal involvement in Hodgkin and non-Hodgkin lymphoma patients. PET-CT has a significant advantage for the diagnosis of diffusely infiltrating organs without mass lesions or contrast enhancement compared to CE-CT.Lymphomas are common hematological malignancies that predominantly affect the lymph nodes. However, both non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL) may affect any organ or tissue in the body. The lymphomatous infiltration of tissues other than the lymph nodes or lymphoid organs is described as extranodal lymphoma. The most common sites of lymphomatous infiltration are skin, stomach, spleen, Waldeyer’s ring, central nervous system, bone, and lungs. The distribution and prevalence of affected organs vary according to the histological type and stage of the disease (1–4).The presence of extranodal involvement is very important for staging NHL and HL. In general, extranodal involvement is more common in NHL than in HL, while it is frequently observed in recurrent disease and immune deficiency-related lymphomas (2–4). Moreover, primary and secondary extranodal diseases have different prognostic implications. Lymphomas that initially appear to have the bulk of the disease at extranodal sites are described in primary extranodal lymphoma and categorized as stage I or II. In secondary extranodal lymphoma, there is secondary involvement of the extranodal sites from primary nodal disease, which is categorized as stage III or IV. Except for the thymus and spleen, extranodal infiltration also indicates stage IV disease in HL. All of these data demonstrate the vital importance of diagnosis of extranodal lymphoma when designing treatment protocols at primary staging or restaging (3–5).Cross-sectional anatomical imaging techniques, particularly computed tomography (CT), have been the primary modality for the diagnosis, staging, restaging, and follow-up of patients with lymphoma. However, these modalities have several limitations when detecting nodal or extranodal disease, because CT is based only on anatomical structural changes, such as the enlargement of lymph nodes or organs, presence of masses, and abnormal contrast enhancements. In NHL or HL, these structural abnormalities are detected in 60% to 90% of patients by CT (6–8). Normal-sized organs or nodes and diffuse lymphomatous infiltrations without mass effects reduce the sensitivity of anatomical imaging modalities.Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography-computed tomography (PET-CT) is a hybrid imaging technique that simultaneously provides functional and anatomical information. This provides a significant advantage for the evaluation of lymphoproliferative malignancies, particularly for the detection of lymphomatous involvement in organs and nodes of normal size without any mass. Several studies suggest that the sensitivity and specificity of ¹⁸F-FDG PET-CT for the assessment of nodal and extranodal involvement were higher than those of standard contrast-enhanced CT (CECT) (3, 4, 7–11). These benefits make ¹⁸F-FDG PET-CT the standard imaging technique for the initial staging, therapy response evaluation and restaging of patients with lymphoma.The aim of this study was to evaluate the utility of ¹⁸F-FDG PET-CT involving care-dose unenhanced CT for the detection of extranodal involvement in patients with NHL and HL. The ¹⁸F-FDG PET-CT results were retrospectively compared with the diagnostic CE-CT data; follow-up results were used as a reference standard.     

Hodgkin disease: clinical utility of CT in initial staging and treatment

One hundred seven consecutive new cases of Hodgkin disease were evaluated with chest radiography and computed tomography (CT) for initial staging. The data were evaluated with regard to five popular treatment protocols for Hodgkin disease. Thoracic CT scans were normal in 30 of 31 patients who had normal radiographs. In the remaining 76 patients, CT demonstrated 194 new sites of disease and disproved 25 suspected sites of disease. The use of CT scans changed the staging of disease in 20 patients, 16 of whom had extranodal extension. The effect of using CT findings on treatment depended on whether radiation therapy was used, and, if so, which treatment protocol was followed. The use of CT findings would have changed the treatment in 6.5%-62.7% of new cases of Hodgkin disease. The authors recommend that CT scans be obtained in all patients with Hodgkin disease, especially those with abnormal chest radiographs.     

Planning mantle radiation therapy in patients with Hodgkin disease: role of gallium-67 scintigraphy

Detection of all sites of lymphoma is imperative for accurate planning of radiation therapy. In patients with Hodgkin disease, mantle radiation is used to treat the thoracic lymph nodes; in those with early-stage or nonbulky disease, mantle and paraaortic radiation may be the only treatment given. CT scanning of the chest adds important information to that obtained from chest radiographs. Gallium-67 scintigraphy has also been used to provide additional information on sites of active tumor. To determine the usefulness of 67Ga-citrate scintigraphy in planning the portals for radiation therapy, we analyzed the radiation treatment plans in 26 consecutive patients with Hodgkin disease; in all 26 patients, the disease had been staged by chest radiographs, chest CT scans, and gallium-67 images. Gallium-67 imaging alone provided unique information that affected the treatment plans in three patients (12%). The combined results of gallium-67 imaging and CT scans influenced the planning of radiation therapy in eight patients (31%). Gallium-67 imaging was found to be an important adjunctive study for optimal planning of radiation therapy in patients with Hodgkin disease.     

Imaging of chest wall disorders.

Pathologic processes that may involve the chest wall include congenital and developmental anomalies, inflammatory and infectious diseases, and soft-tissue and bone tumors. Many of these processes have characteristic radiologic appearances that allow definitive diagnosis. Sternal deformities can be visualized at radiography and their severity quantified with computed tomography (CT). In cervical rib, CT with multiplanar reconstruction may demonstrate relevant anatomic detail and the relationship between bone deformity and arterial compression. In Poland syndrome, radiography reveals an area of hyperlucency on the affected side, whereas CT demonstrates the absence of the greater pectoral muscle and clearly depicts associated musculoskeletal anomalies. Tuberculosis typically manifests at radiography and CT as osseous and cartilaginous destruction and soft-tissue masses with calcification and rim enhancement. Aspergillosis involving the chest wall manifests as pulmonary consolidations and permeative osteolytic changes of the rib and spine at CT and as an area of increased signal intensity at T2-weighted magnetic resonance (MR) imaging. Neurogenic tumors and hemangiomas also typically have high signal intensity at T2-weighted MR imaging. Apparent mass extension or unequivocal bone destruction seen at CT or MR imaging may indicate chest wall involvement by lymphoma. Radiologically, soft-tissue sarcomas typically appear as areas of soft-tissue density or attenuation, often associated with necrotic areas of low density or attenuation. At radiography, plasmacytoma typically manifests as well-defined, "punched-out" lytic lesions with associated extrapleural soft-tissue masses. Chondrosarcoma frequently appears as a large, lobulated excrescent mass arising from a rib with scattered flocculent calcifications characteristic of its cartilaginous mix. Familiarity with these radiologic features facilitates accurate diagnosis and optimal patient treatment.     

Crohn's disease evaluation: comparison of contrast-enhanced MR imaging and single-phase helical CT scanning

The purpose of this study was to evaluate the use of gadolinium and barium-enhanced magnetic resonance (MR) imaging in detecting intestinal and extraintestinal Crohn's disease and compare MRI with contrast-enhanced helical computed tomography (CT). Twenty-six patients with Crohn's disease underwent imaging examinations, including gadolinium-enhanced, fat suppressed fast multiplanar spoiled gradient-recalled (FMPSPGR) MR imaging with oral 2% barium sulfate and rectal water and with helical CT using i.v. and positive (13) or negative (13) intestinal contrast material. MR images and CT scans were reviewed separately by two radiologists for bowel wall thickness and enhancement, presence of abscess, phlegmon, and fistula. MR images and CT scans were then compared side by side. Surgical, endoscopic, and histopathologic findings and results of barium studies were reviewed to determine the location and severity of involvement of intestinal Crohn's disease. Depiction of mural thickening and/or enhancement was superior on the MR images, which showed 55 (85%) and 52 (80%) of 65 abnormal bowel segments for the two observers, compared with helical CT, which showed 39 (60%) and 42 (65%; P < 0.001, P < 0.05) of bowel segments affected by Crohn's disease. Segments of bowel with moderate or marked mural thickening were depicted equally on MR imaging and helical CT. In mildly diseased segments of bowel, with only slight thickening and enhancement, MR imaging depicted 22 (79%) and 19 (68%) of 28 segments, compared with helical CT, which depicted 9 (32%; P < 0.01), and 13 (46%; P > 0.05) of 28 segments. In the side-by side comparison, MR imaging was preferred over helical CT for depicting normal bowel wall (MR 71%, CT 4%, equal 25%; P < 0.001), mural thickening (MR 41%, CT 11% equal 48%; P < 0.01), mural enhancement (MR 89%, equal 11%; P < 0.001), and overall GI tract evaluation (MR 52%, CT 10%, equal 38%; P < 0.001). Gadolinium-enhanced MR imaging with oral dilute barium sulfate and rectal water depicts intestinal and extraintestinal changes of Crohn's disease and shows promise as a clinically useful tool.     

Lymphomas of the head and neck: CT findings at initial presentation

CT findings were reviewed in 68 patients with untreated head and neck lymphoma. More than half of the patients with either Hodgkin's disease or non-Hodgkin's lymphoma were detected in the earlier stages (stage I or II). Four types of abnormalities were identified with CT: nodal involvement alone (type 1), extranodal involvement alone (type 2), a combination of extranodal and nodal disease (type 3), and multifocal extranodal disease with or without nodal involvement (type 4). In the 18 patients with Hodgkin's disease, a subgroup of mixed cellularity was most common; type 1 was the prevailing CT presentation, and no type 2 or 4 lesions were observed. In the 50 patients with non-Hodgkin's lymphoma, diffuse large-cell lymphoma was the most common histologic subtype, and the most common CT presentation was type 2, followed by type 3. Lymphomatous nodes may be extensive and confluent, but often they are smaller than 2 cm and rarely are necrotized. The most frequent extranodal sites of head and neck lymphomas are Waldeyer's ring, paranasal sinuses, and nasal cavity. Extranodal lymphoma cannot be differentiated reliably from the more commonly occurring carcinoma, although it is less often associated with invasion and destruction of adjacent bony structures. Multiple sites of extranodal involvement, with or without neck lymphadenopathy, may suggest a diagnosis of non-Hodgkin's lymphoma.     

Radiologic staging of primary bone sarcoma: MR imaging, scintigraphy, angiography, and CT correlated with pathologic examination

The relative value of magnetic resonance (MR) imaging, computed tomography (CT), technetium-99m bone scintigraphy, and angiography in local tumor staging was prospectively evaluated in 56 patients with primary bone sarcoma. The results of imaging were correlated with findings at surgery and at dissection of the resected specimens. MR imaging was significantly superior to CT and scintigraphy in defining intraosseous tumor length and was as accurate as CT in demonstrating cortical bone and joint involvement. It was definitely superior to CT in demonstrating involvement of muscle compartments. MR imaging was also the best modality in exhibiting the relationship between tumor and major neurovascular bundles; however, these differences were not significant. It is concluded that MR imaging is the modality of choice for local staging of primary bone sarcoma.     

Initial experience with FSE STIR whole-body MR imaging for staging lymphoma in children

Our objective was to compare fast spin-echo (FSE) short inversion time inversion recovery (STIR) whole-body MR imaging with standard procedures in staging children with lymphoma. Eight children (age range, 2–16 years) underwent multi-station FSE STIR whole-body MR at initial staging (n=5) or for restaging following completion of therapy (n=5). Whole-body MR and conventional staging procedures, including CT (n=10), gallium-67 scintigraphy (n=9), bone scintigraphy (n=3) and bone marrow biopsy (n=7) were retrospectively compared for detection of sites involved by lymphoma and for the assigned stage. FSE STIR whole-body MR detected more sites of possible lymphomatous involvement at initial staging (87/88) and at restaging (5/5) than did conventional imaging (74/88, 3/5). MR was more sensitive than conventional imaging in detecting bone marrow involvement at initial staging. Following treatment, however, residual and therapy-induced bone marrow signal abnormalities could not be differentiated from lymphomatous involvement. Detection of nodal and visceral involvement correlated well. Our results suggest that FSE STIR whole-body MR imaging is a sensitive technique for evaluating lymphomatous involvement of bone marrow as well as non-marrow sites. Larger prospective trials are needed to determine if FSE STIR whole-body MR can replace standard radiographic procedures for initial staging and contribute in the follow-up of lymphoma in children.     

Fluorine-18 fluorodeoxyglucose PET/CT patterns of extranodal involvement in patients with Non-Hodgkin lymphoma and Hodgkin's disease

Lymphoma may originate in extranodal sites. Extranodal lymphoma may also be secondary to and accompany nodal disease. Fluorine-18 fluorodeoxyglucose (18F-FDG) imaging has an essential role in the staging of lymphoma, in monitoring the response to therapy, and in detection of recurrence. The introduction of 18F-FDG PET/CT hybrid imaging allows for accurate localization of disease and may be specifically beneficial for the detection of unexpected extranodal sites of disease or exclusion of disease in the presence of nonspecific extranodal CT findings. Accurate staging and localization often dictate the appropriate treatment strategy in patients with lymphoma. Therefore, at any stage in the course of the disease, the potential presence of extranodal disease should be considered when interpreting 18F-FDG PET/CT studies in patients with non-Hodgkin lymphoma and Hodgkin's disease.