Computed tomography (CT) has become the predominant test for diagnosing acute appendicitis in adults. In children and young adults, exposure to CT radiation is of particular concern. We evaluated the rate of negative (unnecessary) appendectomy after low-dose versus standard-dose abdominal CT in young adults with suspected appendicitis.

Background: Cryptogenic hepatocellular carcinoma (HCC) is thought to arise due to non-alcoholic fatty liver disease (NAFLD). This study investigated the prevalence, clinical features, and outcomes of cryptogenic HCC and compared them with those of HCC related to hepatitis B virus infection (HBV-HCC), hepatitis C virus infection (HCV-HCC), and alcohol (ALC-HCC) in Korea.Methods: The clinical features, treatment modalities, and survival data for 480 patients with HCC consecutively enrolled from January 2003 to June 2012 were analyzed. Computed tomography images were used to measure the visceral fat area (VFA) and liver-spleen density ratio.Results: Cryptogenic HCC accounted for 6.8% of all HCC cases, whereas HBV-HCC, HCV-HCC, and ALC-HCC accounted for 62.7%, 13.5%, and 10.7% of HCC cases, respectively. The cryptogenic HCC group was characterized by older age, a low proportion of male patients, a high proportion of patients with metabolic syndrome or single nodular presentation, and a low proportion of patients with portal vein invasion compared to the viral-HCC and ALC-HCC groups. However, Child Pugh classes, tumor stages, and overall survival rates of cryptogenic HCC patients were similar to those of patients with HCC of other etiologies. VFA in cryptogenic HCC patients was significantly higher than that in viral-HCC patients, but similar to that in ALC-HCC patients. The liver-spleen density ratio did not vary according to HCC etiology.Conclusions: Cryptogenic HCC accounts for approximately 7% of HCC cases in Korea, associated with an older age at diagnosis, more frequent occurrence of metabolic syndrome, and less aggressive tumor characteristics, but similar survival compared to viral-HCC or ALC-HCC. Based on VFA and the liver-to-spleen density ratio, cryptogenic HCC may be burnt-out NAFLD in which visceral fat remains but liver fat is depleted.

The detection rate of early stage hepatocellular carcinoma (HCC) was not improved by adding perfluorobutane-enhanced US to conventional B-mode US; however, the rate of false referrals was reduced w... Background US has served as a standard surveillance tool for hepatocellular carcinoma (HCC); however, the detection rate and false referral rate with this modality are suboptimal. Purpose To evalua...

To determine the frequency of normal appendix visualization at low-dose (LD) unenhanced computed tomography (CT) performed with a 16- or 64-detector row scanner when images are reviewed by using the sliding slab averaging technique.The institutional review board approved the study and waived the informed consent requirement. A total of 259 patients, 37 (14.3%) of whom had previously undergone appendectomy, underwent LD unenhanced CT (mean effective dose, 1.7 mSv) performed with a 16- or 64-detector row scanner to assess urinary colic. Three readers used the sliding slab averaging technique to retrospectively review the thin-section (0.67- or 2.00-mm section thickness) images and grade the appendix as absent, unsurely or partly visualized, or clearly and entirely visualized. Interobserver agreement was measured with weighted kappa statistics. McNemar tests were used to compare sensitivity between the readers. Logistic regression analysis was performed to assess the effects of body mass index, patient sex, and type of CT scanner on appendiceal visualization.The kappa statistics for each reader pair were as follows: 0.97 for agreement between readers 1 and 2, 0.93 for agreement between readers 2 and 3, and 0.92 for agreement between readers 1 and 3. Each reader clearly identified the entire appendix in 213 (96.0%), 209 (94.1%), and 205 (92.3%) of the 222 patients without a history of appendectomy. When unsurely or partly visualized appendices were included, the frequencies increased to 99.1% (n = 220), 98.7% (n = 219), and 97.3% (n = 216), respectively, for readers 1, 2, and 3. These frequencies rarely differed between the readers. (P values ranged from .021 to greater than .99.) The three readers consistently reported that the appendix was not visualized in the 37 patients who had undergone appendectomy. None of the tested variables significantly affected appendix visualization.Most normal appendices are visualized on thin-section LD unenhanced CT images reviewed with the sliding slab averaging technique.