PURPOSE: To determine the frequency and natural course of mediastinal masses in asymptomatic people at high risk for lung cancer who were undergoing computed tomographic (CT) screening. MATERIALS AND METHODS: Informed consent and institutional review board approval for this HIPAA-compliant study were obtained at each participating institution. All documented mediastinal masses among the 9263 baseline and 11 126 annual repeat screenings performed in the Early Lung Cancer Action Project (ELCAP) and its successor project, the New York ELCAP, were identified. Two radiologists confirmed all cases, identified the location and measured the diameter (average of length and width) of each mass, and reviewed all subsequent CT and clinical and surgical results. The prevalence and incidence of mediastinal masses were then determined. RESULTS: Of the 9263 individuals, 71 had a mediastinal mass seen at baseline screening (prevalence of 0.77%). Of the 71 masses, 41 were thymic, 16 were thyroidal, two were esophageal cancers, six were tracheal-esophageal diverticula, and six were other masses. Among the 11 126 annual repeat screenings, only one new mediastinal mass was identified (incidence of 0.01%). This suggests a long average duration for mediastinal masses in asymptomatic people. Among the 41 thymic masses, five were larger than 3.0 cm in diameter, and all five were resected; of these five, one was a thymic carcinoma and four were noninvasive thymomas. Of the remaining 36 thymic masses, 25 were evaluated at follow-up CT 1 year later: Five had increased in diameter, two had decreased, and 18 remained unchanged. All 16 thyroid masses were due to goiter; none of these were changed at follow-up CT 1 year later. CONCLUSION: Mediastinal masses found in the context of CT screening for lung cancer in asymptomatic people should be approached in a

OBJECTIVE: To evaluate the ability of contrast-enhanced transrectal ultrasonography (CETRUS) to detect and localize prostate index tumor. METHODS: Eighty-three patients with biopsy-proven prostate cancer (PCa), who were scheduled to undergo radical prostatectomy, were enrolled in this prospective study. Each patient underwent baseline grayscale and CETRUS imaging of the prostate according to a standardized protocol before the operation. Ultrasonography findings (CETRUS and grayscale imaging) were correlated with step-section histopathology. RESULTS: Overall, 53 and 68 tumor foci were detected by grayscale imaging and CETRUS, respectively. The combination of grayscale imaging and CETRUS allowed identification of 89 of the 232 cancer foci (38.4%). The sensitivity of combined imaging was significantly superior to that of grayscale imaging (P<.01) and CETRUS (P<.05). Additionally, the prostate index tumor detection rate by the use of grayscale imaging, CETRUS, and their combination was 42 of 83 (50.6%), 53 of 83 (63.9%), and 67 of 83 (80.7%), respectively. The combined approach performed significantly better than grayscale and CETRUS imaging (P<.001 and P<.05, respectively). The index tumor detection rate of CETRUS was higher than that of grayscale imaging, but no significant difference was found (P>.05). CONCLUSION: Our study has demonstrated significantly improved detection of both PCa and index tumor with a combined approach of CETRUS and grayscale imaging compared with baseline grayscale technique only, and this technique may be applicable to focal therapy of PCa.

The energy spectrum of X-ray photons after passage through an absorber contains information about its elemental composition. Thus, tissue characterisation becomes feasible provided that absorption characteristics can be measured or differentiated. Dual-energy CT uses two X-ray spectra enabling material differentiation by analysing material-dependent photo-electric and Compton effects. Elemental concentrations can thereby be determined using three-material decomposition algorithms. In comparison to dual-energy CT used in clinical practice, recently developed energy-sensitive photon-counting detectors sample the material-specific attenuation curves at multiple energy levels and within narrow energy bands; the latter allows the detection of element-specific, k-edge discontinuities of the photo-electric cross section. Multi-energy CT imaging therefore is able to concurrently identify multiple materials with increased accuracy. These specific data on material distribution provide information beyond morphological CT, and approach functional imaging. This article reviews the principles of dual- and multi-energy CT imaging, hardware approaches and clinical applications.

UNLABELLED: Dual-energy computed tomography (DECT) can amply contribute to support oncological imaging: the DECT technique offers promising clinical applications in oncological imaging for tumour detection and characterisation while concurrently reducing the radiation dose. Fast image acquisition at two different X-ray energies enables the determination of tissue- or material-specific features, the calculation of virtual unenhanced images and the quantification of contrast medium uptake; thus, tissue can be characterised and subsequently monitored for any changes during treatment. DECT is already widely used, but its potential in the context of oncological imaging has not been fully exploited yet. The technology is the subject of ongoing innovation and increasingly with respect to its clinical potential, particularly in oncology. This review highlights recent state-of-the-art DECT techniques with a strong emphasis on ongoing DECT developments relevant to oncologic imaging, and then focuses on clinical DECT applications, especially its prospective uses in areas of oncological imaging. KEY POINTS: * Dual-energy CT (DECT) offers fast, robust, quantitative and functional whole-body imaging. * DECT provides improved tumour detection and more detailed tissue differentiation and characterisation. * DECT affords therapy monitoring with complementary information and reduced radiation dose. * The use of DECT in oncology is of increasing clinical importance. * The potential of DECT in oncology has not been fully exploited yet.