Recent innovations in computed tomographic (CT) hardware and software have allowed implementation of low tube voltage imaging into everyday CT scanning protocols in adults. CT at a low tube voltage setting has many benefits, including (a) radiation dose reduction, which is crucial in young patients and those with chronic medical conditions undergoing serial CT examinations for disease management; and (b) higher contrast enhancement. For the latter, increased attenuation of iodinated contrast material improves the evaluation of hypervascular lesions, vascular structures, intestinal mucosa in patients with bowel disease, and CT urographic images. Additionally, the higher contrast enhancement may provide diagnostic images in patients with renal dysfunction receiving a reduced contrast material load and in patients with suboptimal peripheral intravenous access who require a lower contrast material injection rate. One limitation is that noisier images affect image quality at a low tube voltage setting. The development of denoising algorithms such as iterative reconstruction has made it possible to perform CT at a low tube voltage setting without compromising diagnostic confidence. Other potential pitfalls of low tube voltage CT include (a) photon starvation artifact in larger patients, (b) accentuation of streak artifacts, and (c) alteration of the CT attenuation value, which may affect evaluation of lesions on the basis of conventional enhancement thresholds. CT of the abdomen with a low tube voltage setting is an excellent radiation reduction technique when properly applied to imaging of select patients in the appropriate clinical setting.

Early diagnosis and treatment of hepatocellular carcinoma are important because only 10% of patients meet the criteria for curative therapy at the time of diagnosis. Several organizations have developed guidelines for screening, diagnosis, and treatment of hepatocellular carcinoma. Radiologists play a pivotal role in every aspect of these guidelines.

The purpose of our study was to evaluate the reproducibility of Modified Response Evaluation Criteria in Solid Tumors (mRECIST) in hepatocellular carcinoma (HCC) lesions undergoing transarterial radioembolization (TARE) therapy and to determine whether mRECIST reproducibility is affected by the enhancement pattern of HCC. One hundred and three HCC lesions from 103 patients treated with TARE were evaluated. The single longest diameter of viable tumor tissue was measured by two radiologists at baseline; response to therapy was evaluated according to mRECIST. The enhancement pattern of HCC lesions was correlated with their mRECIST response. The response rate between mRECIST and RECIST 1.1 was compared. Wilcoxon signed-rank test, paired t test, Lin's concordance correlation coefficient (q c ), Bland-Altman plot, kappa statistics, and Fisher's exact test were used to assess intra-and interobserver reproducibilities and to compare response rates. There were better intra-than interobserver agreements in the measurement of single longest diameter of viable tumor tissue (bias 5 0 cm intraobserver versus bias 5 0.3 cm interobserver). For mRECIST, good intraobserver (OE 5 0.70) and moderate interobserver (OE 5 0.56) agreements were noted. The mRECIST response for HCC lesions with homogeneous enhancement at both baseline and follow-up imaging showed better intra-and interobserver agreements (OE 5 0.77 and 0.60, respectively) than lesions with heterogeneous enhancement at both scans (OE 5 0.54 and 0.40, respectively). In the early follow-up period mRECIST showed a significantly higher response rate than RECIST (40.8% versus 3.9%; P 5 0.025). Conclusions: In HCC patients treated with TARE, mRE-CIST captures a significantly higher response rate compared with RECIST; it also demonstrates acceptable intra-and interobserver reproducibilities for HCC lesions treated with TARE, and mRECIST reproducibility may be lower for HCC lesions with heterogeneous distribution of the viable tumor tissue. (HEPATOLOGY 2015;62:1111-1121

Gallbladder perforation is a potentially life-threatening condition commonly seen as a complication of acute cholecystitis. Urgent surgical intervention is often needed to reduce serious morbidity and mortality. It presents a diagnostic challenge due to nonspecific symptoms, leading to a delay in diagnosis. Imaging plays a vital role in early identification of this potentially fatal condition and evaluation by more than one imaging modality may be required to make the diagnosis. Knowledge of specific and ancillary imaging findings is crucial to avoid misdiagnosis. In this article, we will review the risk factors, pathophysiology, and surgical classification of gallbladder perforation and discuss the role of multimodality imaging in its diagnosis. Differential diagnoses on imaging will also be discussed.