MRI features of treated hepatocellular carcinoma following locoregional therapy: a pictorial review.

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide and within the United States. Liver transplant or partial liver resection is the definitive treatment of choice for HCC; however, the majority of cases are detected in advanced stages due to its early-stage asymptomatic nature, often precluding surgical treatment. Locoregional therapy plays an essential role in HCC management, including curative intent, as a bridge to transplant, or in some cases palliative therapy. Radiologists play a critical role in assessing tumor response following treatment to guide further management that may potentially impact transplantation eligibility; therefore, it is important for radiologists to have an understanding of different locoregional therapies and the variations of imaging response to different therapies. In this review article, we outline the imaging response to ablative therapy (AT), transarterial chemoembolization (TACE), selective internal radiation therapy (SIRT), and stereotactic body radiation therapy (SBRT). We will also briefly discuss the basic concepts of these locoregional therapies. This review focuses on the imaging features following locoregional treatment for hepatocellular carcinoma following AT, TACE, SIRT, and SBRT.

Virtual Monoenergetic Spectral Detector CT for Preoperative CT Angiography in Liver Donors.

OBJECTIVE: The purpose of this study was to evaluate the use of virtual monoenergetic images (VMI) in pre-operative CT angiography of potential donors for living donor adult liver transplantation (LDALT), and to determine the optimal energy level to maximize vascular signal-to-noise and contrast-to-noise ratios (SNR and CNR, respectively). MATERIALS AND METHODS: We retrospectively evaluated 29 CT angiography studies performed preoperatively in potential liver donors on a spectral detector CT scanner. All studies included arterial, early venous, and delayed venous phase imaging. Conventional polyenergetic images were generated for each patient, as well as virtual monoenergetic images in 10 keV increments from 40 -100 keV. Arteries (aorta and celiac, superior mesenteric, common hepatic, right and left hepatic arteries) were assessed on arterial phase images; portal venous system branches (splenic, superior mesenteric, main, right, and left portal veins) on early venous phase images; and hepatic veins on late venous phase images. Vascular attenuation, background parenchymal attenuation, and noise were measured on each set of virtual monoenergetic and conventional images. RESULTS: Background hepatic and vascular noise decreased with increasing keV, with the lowest noise at 100 keV. Vascular SNR and CNR increased with decreasing keV and were highest at 40 keV, with statistical significance compared with conventional ( P < 0.05). CONCLUSIONS: In preoperative CT angiography for potential liver donors, the optimal keV for assessing the vasculature to improve SNR and CNR is 40 keV. Use of low keV VMI in LDALT CT protocols may facilitate detection of vascular anatomical variants that can impact surgical planning.

Usage of an Electronic Database and Checklist System for Improvement in Magnetic Resonance Imaging Acquisition.

PURPOSE: To determine whether implementation of an easily accessible electronic database promotes significant reporting of magnetic resonance imaging (MRI) acquisition errors. Additionally, we wanted to see if analysis of the error reports could be used to create a comprehensive checklist to avoid the most common errors. METHODS: A new, simple, and efficient electronic database reporting system was written in-house and implemented at our institution. Over the course of 4 months, the use of this database enabled collection and analysis of sufficient data for trend analysis. A simple 4-point checklist for MRI technologist use was developed based on the most commonly reported errors. Reported MRI acquisition error rates were collected and analyzed thereafter. RESULTS: By the first full month of implementation, MRI scan error reporting increased from a previous negligible baseline rate to 3.03%. The comprehensive checklist was based on the 4 most common issues reported. Verification of checklist use showed that adherence to this requirement averaged greater than 94%. Immediately following roll out of the checklist, the percentage of errors reported fell to 1.7% with a continued decline in error reports thereafter. An approximately 60% reduction in errors in the last month of the study was evident as compared to the first month of data collection. CONCLUSIONS: The use of an efficient error reporting system and implementation of a checklist based on the most common MRI acquisition errors results in a substantial decrease in the baseline MRI acquisition error rates.

ACR Appropriateness Criteria® Acute Nonlocalized Abdominal Pain.

The range of pathology in adults that can produce abdominal pain is broad and necessitates an imaging approach to evaluate many different organ systems. Although localizing pain prompts directed imaging/management, clinical presentations may vary and result in nonlocalized symptoms. This review focuses on imaging the adult population with nonlocalized abdominal pain, including patients with fever, recent abdominal surgery, or neutropenia. Imaging of the entire abdomen and pelvis to evaluate for infectious or inflammatory processes of the abdominal viscera and solid organs, abdominal and pelvic neoplasms, and screen for ischemic or vascular etiologies is essential for prompt diagnosis and treatment. Often the first-line modality, CT quickly evaluates the abdomen/pelvis, providing for accurate diagnoses and management of patients with abdominal pain. Ultrasound and tailored MRI protocols may be useful as first-line imaging studies, especially in pregnant patients. In the postoperative abdomen, fluoroscopy may help detect anastomotic leaks/abscesses. While often performed, abdominal radiographs may not alter management. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Self-renewal of human embryonic stem cells is supported by a shortened G1 cell cycle phase.

Competency for self-renewal of human embryonic stem (ES) cells is linked to pluripotency. However, there is a critical paucity of fundamental parameters of human ES cell division. In this study we show that human ES cells (H1 and H9; NIH-designated WA01 and WA09) rapidly proliferate due to a very short overall cell cycle (15-16 h) compared to somatic cells (e.g., normal diploid IMR90 fibroblasts and NT-2 teratocarcinoma cells). The human ES cell cycle maintains the four canonical cell cycle stages G1, S, G2, and M, but the duration of G1 is dramatically shortened. Bromodeoxyuridine (BrdU) incorporation and FACS analysis demonstrated that 65% of asynchronously growing human ES cells are in S phase. Immunofluorescence microscopy studies detecting BrdU labeled mitotic chromosomes, Ki67 domains, and p220(NPAT) containing Cajal bodies revealed that the durations of the S ( approximately 8 h), G2 ( approximately 4 h), and M phases ( approximately 1 h) are similar in ES and somatic cells. We determined that human ES cells remain viable after synchronization with either nocodazole or the anti-tumor drug Paclitaxel (taxol) and have an abbreviated G1 phase of only 2.5-3 h that is significantly shorter than in somatic cells. Molecular analyses using quantitative RT-PCR demonstrate that human ES cells and somatic cells express similar cell cycle markers. However, among cyclins and cyclin-dependent kinases (CDKs), we observed high mRNA levels for the G1-related CDK4 and cyclin D2 genes. We conclude that human ES cells exhibit unique G1 cell cycle kinetics and use CDK4/cyclin D2 related mechanisms to attain competency for DNA replication.