Diffusion-weighted magnetic resonance imaging (DWI) provides functional information and can be used for the detection and characterization of pathologic processes, including malignant tumors. The recently introduced concept of "diffusion-weighted whole-body imaging with background body signal suppression" (DWIBS) now allows acquisition of volumetric diffusionweighted images of the entire body. This new concept has unique features different from conventional DWI and may play an important role in wholebody oncological imaging. This review describes and illustrates the basics of DWI, the features of DWIBS, and its potential applications in oncology.

• Iterative reconstruction technology for CT is presented in non-mathematical terms. • IR reduces noise and artefacts compared to filtered back-projection. • IR can improve image quality in routine-dose CT and lower the radiation dose. • IR's disadvantages include longer computation and blotchy appearance of some images.

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Purpose:To compare and determine the reproducibility of apparent diffusion coefficient (ADC) measurements of the normal liver parenchyma in breathhold, respiratory triggered, and free-breathing diffusion-weighted magnetic resonance imaging (DWI). Materials and Methods:Eleven healthy volunteers underwent three series of DWI. Each DWI series consisted of one breathhold, one respiratory triggered, and two freebreathing (thick and thin slice acquisition) scans of the liver, at b-values of 0 and 500 s/mm 2 . ADCs of the liver parenchyma were compared by using nonparametric tests. Reproducibility was assessed by the Bland-Altman method. Results: Mean ADCs (in 10Ϫ3 mm 2 /sec) in respiratory triggered DWI (2.07-2.27) were significantly higher than mean ADCs in breathhold DWI (1.57-1.62), thick slice freebreathing DWI (1.62-1.65), and thin slice free-breathing DWI (1.57-1.66) (P Ͻ 0.005). Ranges of mean difference in ADC measurement Ϯ limits of agreement between two scans were Ϫ0.02-0.05 Ϯ 0.16 -0.24 in breathhold DWI, Ϫ0.14 -0.20 Ϯ 0.59 -0.60 in respiratory triggered DWI, Ϫ0.03-0.03 Ϯ 0.20 -0.29 in thick slice free-breathing DWI, and Ϫ0.01-0.09 Ϯ 0.21-0.29 in thin slice free-breathing DWI.Conclusion: ADC measurements of the normal liver parenchyma in respiratory triggered DWI are significantly higher and less reproducible than in breathhold and free-breathing DWI.

We found evidence that CT-related radiation exposure increases brain tumor risk. No association was observed for leukemia. Compared with the general population, incidence of brain tumors was higher in the cohort of children with CT scans, requiring cautious interpretation of the findings.

IntroductionThe malignant lymphomas, Hodgkin disease (HD) and nonHodgkin lymphoma (NHL), comprise approximately 5% to 6% of all malignancies and are the fifth most frequently occurring type of cancer in the United States. In 2007, an estimated 9260 new cases of HD and 81 850 new cases of NHL will be diagnosed in the United States. 1 Once the diagnosis HD or NHL has been established by biopsy of a particular site, determination of disease extent (staging) is important for appropriate treatment planning and determining prognosis. In addition, knowing the sites of involvement at time of diagnosis makes it possible to accurately restage at the end of therapy and document a complete remission. 2,3 Staging of HD and NHL is based on the Ann Arbor classification with the addition of a definition of bulky disease often referred to as the Cotswold modification (Table 1). This staging system encompasses the number of sites of disease involved, the type of involvement (nodal or extranodal), and the distribution of disease. 4 Computed tomography (CT) is currently the most commonly used means for staging patients with malignant lymphoma. 2,3 However, CT lacks functional information, which impedes identification of disease in normal-sized organs. 18 F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) may be an alternative to CT. 5,6 Other promising alternatives to CT are FDG-PET/CT fusion 7,8 and whole-body magnetic resonance imaging (WB-MRI). 9,10 The purpose of this study is to provide an up-to-date overview of the diagnostic performance of CT, FDG-PET, FDG-PET/CT fusion, and WB-MRI in staging of malignant lymphoma.In the first part of this article, technical aspects and procedures of each imaging modality are summarized. Subsequently, we describe our literature search strategy, study selection methods, and study analysis. Next, literature search results and results of analyzed articles are demonstrated. Finally, results are discussed, and advantages, drawbacks, and limitations of each imaging technique are outlined. Technical aspects and procedures CTBefore the CT era, patients with a diagnosis of malignant lymphoma were subjected to a battery of radiologic studies that included chest radiography, intravenous pyelography, lymphangiography, skeletal surveys, and isotope scans. On top of this, most patients with HD underwent staging laparotomy with its attendant risks. 11 The introduction of CT in the early 1970s was a tremendous breakthrough in noninvasive imaging, and its potential for staging malignant lymphoma was soon recognized and investigated. 12 Since then, CT has gradually become the imaging modality of choice for staging malignant lymphoma. CT technology has continuously been developed and refined; major milestones include the introduction of spiral CT in the early 1990s and the advent of multidetector-row CT in 1998. The concept of multidetector-row CT deserves special attention; multidetector-row CT scanners have multiple (X) data acquisition systems connected to multidetector arrays to provide a multi...

• Iterative reconstruction improves image quality of CT images at equal acquisition parameters. • IR preserves image quality compared to normal-dose filtered back-projection. • The reduced radiation dose made possible by IR is advantageous for patients. • IR has not yet been investigated with clinical diagnosis and accuracy as endpoints.

FDG PET/CT is accurate and complementary to BMB for detecting bone marrow involvement in patients with newly diagnosed DLBCL. A negative FDG PET/CT scan cannot rule out the presence of bone marrow involvement, but positive FDG PET/CT findings obviate the need for BMB for the detection of bone marrow involvement in these patients.