Quantitative imaging is the analysis of retrieved numeric data from images with the goal of reducing subjective assessment. It is an increasingly important radiologic tool to assess treatment response in oncology patients. Quantification of response to therapy depends on the tumor type and method of treatment. Anatomic imaging biomarkers that quantify liver tumor response to cytotoxic therapy are based on temporal change in the size of the tumors. Anatomic biomarkers have been incorporated into the World Health Organization criteria and the Response Evaluation Criteria in Solid Tumors (RECIST) versions 1.0 and 1.1. However, the development of novel therapies with different mechanisms of action, such as antiangiogenesis or radioembolization, has required new methods for measuring response to therapy. This need has led to development of tumor- or therapy-specific guidelines such as the Modified CT Response Evaluation (Choi) Criteria for gastrointestinal stromal tumors, the European Association for Study of the Liver (EASL) criteria, and modified RECIST for hepatocellular carcinoma, among many others. The authors review the current quantification criteria used in the evaluation of treatment response in liver tumors, summarizing their indications, advantages, and disadvantages, and discuss future directions with newer methods that have the potential for assessment of treatment response. Knowledge of these quantitative methods is important to facilitate pivotal communication between oncologists and radiologists about cancer treatment, with benefit ultimately accruing to the patient.

Background and Purpose— Paradoxical embolization is frequently posited as a mechanism of ischemic stroke in patients with patent foramen ovale. Several studies have suggested that the deep lower extremity and pelvic veins might be an embolic source in cryptogenic stroke (CS) patients with patent foramen ovale. Methods— Consecutive adult patients with ischemic stroke or transient ischemic attack and a patent foramen ovale who underwent pelvic magnetic resonance venography as part of an inpatient diagnostic evaluation were included in this single-center retrospective observational study to determine pelvic and lower extremity (LE) deep venous thrombosis (DVT) prevalence in CS versus non-CS stroke subtypes. Results— Of 131 patients who met inclusion criteria, 126 (96.2%) also had LE duplex ultrasound data. DVT prevalence overall was 7.6% (95% confidence interval, 4.1–13.6), pelvic DVT 1.5% (95% confidence interval, 0.1–5.8), and LE DVT 7.1% (95% confidence interval, 3.6–13.2). One patient with a pelvic DVT also had a LE DVT. Comparing patients with CS (n=98) with non-CS subtypes (n=33), there was no significant difference in the prevalence of pelvic DVT (2.1% versus 0%, P =1), LE DVT (6.2% versus 10.3%, P =0.43), or any DVT (7.2% versus 9.1%, P =0.71). Conclusions— Among patients with ischemic stroke/transient ischemic attack and patent foramen ovale, the majority of detected DVTs were in LE veins rather than the pelvic veins and did not differ by stroke subtype. The routine inclusion of pelvic magnetic resonance venography in the diagnostic evaluation of CS warrants further prospective investigation.

In patients undergoing CT examination of the chest, abdomen, and pelvis, the combination of attenuation-based automated tube voltage selection with iterative reconstruction significantly reduced radiation dose parameters and maintained objective image quality when compared with standard tube voltage selection associated with filtered backprojection reconstruction.