Unusual association of alveolar rhabdomyosarcoma with pancreatic metastasis: emerging role of PET-CT in tumor staging

Pancreatic metastases in childhood cancer have been rarely reported in the radiology literature although ample evidence exists in pathology reports for its occurrence in patients with alveolar rhabdomyosarcomas (RMS). Assess the occurrence of pancreatic metastases in alveolar rhabdomyosarcomas, increase awareness of this association and reassess current staging protocols. Three major oncology centers reviewed their records and imaging examinations. Patients’ history and demographics, primary tumor site and histology, presence of tumor recurrence, and presence and location of other metastases were reviewed. Pancreatic metastases occurred in eight patients with alveolar RMS. Four of these presented at diagnosis and four with disease recurrence. In recurrent disease, the duration between the diagnosis of the primary tumor and pancreatic metastases varied from 8 months to 6 years (mean ± SD: 2.38 ± 2.49 years). In all patients who received PET scans, pancreatic metastases showed a marked FDG-uptake, but had variable detectability with CT. Pancreatic metastases were not associated with certain primary tumor locations or presence of other metastases, mandating an evaluation of the pancreas in all cases of alveolar rhabdomyosarcomas. Radiologists should be sensitized and actively evaluate the pancreas in patients with alveolar RMS. Optimizing CT and PET-CT protocols may increase the diagnostic yield

Characterization of Pulmonary Metastases in Children With Hepatoblastoma Treated on Children\u27s Oncology Group Protocol AHEP0731 (The Treatment of Children With All Stages of Hepatoblastoma): A Report From the Children\u27s Oncology Group.

Purpose To determine whether the pattern of lung nodules in children with metastatic hepatoblastoma (HB) correlates with outcome. Methods Thirty-two patients with metastatic HB were enrolled on Children\u27s Oncology Group Protocol AHEP0731 and treated with vincristine and irinotecan (VI). Responders to VI received two additional cycles of VI intermixed with six cycles of cisplatin/fluorouracil/vincristine/doxorubicin (C5VD), and nonresponders received six cycles of C5VD alone. Patients were imaged after every two cycles and at the conclusion of therapy. All computed tomography scans and pathology reports were centrally reviewed, and information was collected regarding lung nodule number, size, laterality, timing of resolution, and pulmonary surgery. Results Among the 29 evaluable patients, only 31% met Response Evaluation Criteria in Solid Tumors (RECIST) for measurable metastatic disease. The presence of measurable disease by RECIST, the sum of nodule diameters greater than or equal to the cumulative cohort median size, bilateral disease, and ≥ 10 nodules were each associated with an increased risk for an event-free survival event ( P = .48, P = .08, P = .065, P = .03, respectively), with nodule number meeting statistical significance. Ten patients underwent pulmonary resection/metastasectomy at various time points, the benefit of which could not be determined because of small patient numbers. Conclusion Children with metastatic HB have a poor prognosis. Overall tumor burden may be an important prognostic factor for these patients. Lesions that fail to meet RECIST size criteria (ie, those \u3c 10 mm) at diagnosis may contain viable tumor, whereas residual lesions at the end of therapy may constitute eradicated tumor/scar tissue. Patients may benefit from risk stratification on the basis of the burden of lung metastatic disease at diagnosis

New frontiers in pediatric oncologic imaging

As imaging technologies advance, a paradigm shift is emerging in the assessment of tumor response to therapy. The traditional method of measuring tumor size may not reflect changes in tumor viability induced by chemotherapy and radiation therapy. Today's oncologists and radiologists seek objective methods for assessing tumor metabolism and blood flow, measures that provide earlier, more accurate information about treatment effects. Pediatric imaging presents unique challenges not encountered in adult imaging, including the need for sedation and consideration of the long-term effects of radiation exposure in a growing child. Therefore, the potential risks and benefits of new imaging approaches for monitoring anticancer treatment in children require careful consideration. Several new imaging techniques are currently under investigation for use in pediatric oncology. These include dynamic enhanced magnetic resonance imaging and quantitative contrast-enhanced ultrasonography for assessment of blood flow in solid tumors such as osteosarcoma and neuroblastoma, and nuclear imaging, including positron emission tomography–computed tomography, for assessment of pediatric musculoskeletal tumors and neuroblastoma. The potential value, relative advantages, and limitations of these new methods in monitoring anticancer therapy in children are discussed

The child with bone pain: malignancies and mimickers

Bone pain in children is common. The cause may be as benign as growing pains or as life-threatening as a malignancy. When a cause cannot be established by laboratory tests, physical examination or patient history, imaging of the affected body part is often obtained. Distinguishing benign from malignant processes involving the bones of children, based on imaging findings, can be challenging. The most common benign conditions that mimic pediatric bone tumors on imaging are Langerhan's cell histiocytosis and osteomyelitis. In this review, the current literature regarding the pathology and imaging of these conditions is reviewed. Benign conditions are compared with the most common pediatric bone tumors, Ewing sarcoma and osteosarcoma, with an emphasis on clinical and imaging features that may aid in diagnosis

PET-CT imaging in pediatric oncology

Positron emission tomography (PET)-computed tomography (CT) is emerging as a valuable tool for assessing a wide variety of pediatric malignancies, including lymphomas, soft-tissue tumors, and bone sarcomas. PET-CT may provide information that is not apparent on conventional imaging performed to stage these diseases and monitor their response to treatment. The use of PET-CT in children requires an awareness of the technical and logistical issues unique to this patient population. In addition, interpretation of pediatric PET-CT imaging requires familiarity with aspects of pediatric anatomy and physiology that differ from those of adults. In this article, the technical considerations in performing pediatric PET-CT, pitfalls in the diagnostic use of PET-CT in children, and current and emerging applications of PET-CT in pediatric oncology are reviewed

Automated vessel exclusion technique for quantitative assessment of hepatic iron overload by R2*-MRI

Background: Extraction of liver parenchyma is an important step in the evaluation of R *2 -based hepatic iron content (HIC). Traditionally, this is performed by radiologists via whole-liver contouring and T *2 -thresholding to exclude hepatic vessels. However, the vessel exclusion process is iterative, time-consuming, and susceptible to interreviewer variability. Purpose: To implement and evaluate an automatic hepatic vessel exclusion and parenchyma extraction technique for accurate assessment of R *2 -based HIC. Study Type: Retrospective analysis of clinical data. Subjects: Data from 511 MRI exams performed on 257 patients were analyzed. Field Strength/Sequence: All patients were scanned on a 1.5T scanner using a multiecho gradient echo sequence for clinical monitoring of HIC. Assessment: An automated method based on a multiscale vessel enhancement filter was investigated for three input data types—contrast-optimized composite image, T *2 map, and R *2 map—to segment blood vessels and extract liver tissue for R *2 -based HIC assessment. Segmentation and R *2 results obtained using this automated technique were compared with those from a reference T *2 -thresholding technique performed by a radiologist. Statistical Tests: The Dice similarity coefficient was used to compare the segmentation results between the extracted parenchymas, and linear regression and Bland-Altman analyses were performed to compare the R *2 results, obtained with the automated and reference techniques. Results: Mean liver R *2 values estimated from all three filter-based methods showed excellent agreement with the reference method (slopes 1.04–1.05, R 2 \u3e 0.99, P \u3c 0.001). Parenchyma areas extracted using the reference and automated methods had an average overlap area of 87–88%. The T *2 -thresholding technique included small vessels and pixels at the vessel/tissue boundaries as parenchymal area, potentially causing a small bias (\u3c5%) in R *2 values compared to the automated method. Data Conclusion: The excellent agreement between reference and automated hepatic vessel segmentation methods confirms the accuracy and robustness of the proposed method. This automated approach might improve the radiologist\u27s workflow by reducing the interpretation time and operator dependence for assessing HIC, an important clinical parameter that guides iron overload management. Level of Evidence: 3. Technical Efficacy: Stage 2. J. Magn. Reson. Imaging 2018;47:1542–1551