Human Mesenchymal Stem Cell Reporter Gene Imaging Translatable from Small to Large Animals
Cardiac reporter gene imaging of human mesenchymal stem cells (MSCs) can be translated from small to large animals by using a clinical PET-CT scanner. In micro-PET imaging with the radiotracer 9-(4-[fluorine 18]-fluoro-3-hydroxymethylbutyl)-guanine (FHBG), Willmann and colleagues observed differences in FHBG uptake between the injected and remote myocardium in rats and swine. However, with co-administration of a matrigel as a biopolymer scaffold, signal-to-background ratio increased to 1.87 after human MSC injection in swine and positively correlated with the number of administered human MSCs. The researchers concluded that reporter gene imaging in human MSCs can be translated to large animals and use of a biopolymer scaffold—to increase intramyocardial retention of human MSCs within the first hours after administration—may be critical for optimal delivery and noninvasive tracking of human MSCs.

Digital Mammography Could Lower Recall and Invasive Procedures Rates
Digital mammography (DM) could result in lower recall and invasive test rates than those of screen-film mammography (SFM), mainly in successive screening rounds. In a retrospective study of a population-based breast cancer screening program, Sala and colleagues compared data from 12–958 women who underwent SFM (before DM was introduced) with data from 6074 women who underwent DM. Overall recall rates for SFM and DM groups were 5.5% and 4.2% and invasive test rates were 2.6% and 1.3%, respectively. No significant difference was found in the overall cancer detection rate between DM and SFM groups. Researchers concluded that DM could spare a substantial number of women the consequences of the adverse effects of screening programs.

High-Dose Hepatic Artery Immunoembolization Prolongs Survival of Patients with Metastatic Uveal Melanoma
Hepatic artery immunoembolization (IE) with high-dose granulocyte-macrophage colony-stimulating factor (GM-CSF) prolongs overall survival of patients with metastatic uveal melanoma. Yamamoto and colleagues found in a study of 53 patients that those treated by using IE with high-dose GM-CSF had significantly better overall survival than those treated by using chemoembolization with 1,3-bis (2-chloroethyl)-1-nitrosourea. IE at higher doses may also prevent or delay progression of extrahepatic masses, the researchers found. They proposed that the approach may be used with other hepatic tumors and recommended further investigation on the efficacy and mechanism of high-dose IE.

MR for Rectal Cancer Restaging Can Predict Tumor Downstaging and Lymph Node Involvement
A two-part MR study of locally advanced rectal cancer treated with preoperative radiation therapy plus concomitant chemotherapy (RTCC) reveals that restaging MR 6 weeks after completion of RTCC identifies tumors downstaged to tumors confined to the rectal wall. Dresen and colleagues found that for experienced readers, restaging MR yields high positive predictive value for the prediction of tumor downsizing to a ypT0–2 lesion, especially when morphologic and volumetric criteria are combined. In a similar population, Lahaye and colleagues found that the most reliable predictors for identifying malignant lymph nodes after RTCC by using USPIO-enhanced MR were estimated percentage of white region within the node and ratio of the measured surface area of the white region within the node to the measured surface area of the total node. The researchers agreed that MR restaging could allow clinicians to consider transanal local excision in good responders after RTCC rather than standard surgery.

Optimal Electrocardiographic Pulsing Helps Reduce CT Coronary Angiography Radiation Dose
Optimal electrocardiographic (ECG) pulsing can significantly reduce radiation dose and cancer risk to patients without compromising the diagnostic performance of dual-source CT coronary angiography. In CT coronary angiographic examinations involving standard ECG pulsing in 327 patients and optimal ECG pulsing in 109 patients, Weustink and colleagues found that optimal pulsing yielded sensitivity, specificity, and positive and negative predictive values similar to those of standard pulsing and a 25% overall reduction in mean effective dose. Compared with a nonpulsing protocol, optimal pulsing resulted in a 43% overall reduction in mean effective radiation dose and decreased cancer risk.

MR Reveals Anatomic Variability and Atypical Features in Asymptomatic Elbows
MR imaging of asymptomatic elbows revealed considerable variability in the elbow nerves and features that, in the literature, are considered to be related with compression neuropathy. Husarik and colleagues found increased signal intensity on fluid-sensitive images in the ulnar nerve in 60% of subjects, but this was never observed in the median and radial nerves. They also found an atypical intermuscular course of the median nerve in 17% of subjects, presence of an anconeus epitrochlearis muscle in 23%, and a hypertrophic leash of Henry in 15%. They propose that knowledge of normal elbow variability may help to avoid false-positive diagnoses of suspected neuropathy.

Use of CT Renal Volume–based Model for Estimating Donor Glomerular Filtration Rate
A renal volume–based model used to estimate the renal donor glomerular filtration rate (GFR) from CT scans could be used in place of ¹²⁵I-iothalamate clearance measurement. In a retrospective study of 244 subjects who underwent renal donor evaluation over a 2-year period, Herts and colleagues recorded age, sex, race, height, weight, and serum creatinine level and measured GFR using urinary clearance of ¹²⁵I-iothalamate. Renal volume, age, serum creatinine level, and weight significantly correlated with GFR measured by using ¹²⁵I-iothalamate clearance; sex, race, and height were not significant. Researchers concluded that renal volume correlates strongly with GFR measured by using ¹²⁵I-iothalamate clearance and outperforms the modification of diet in renal disease equation in potential living renal donors.

Healthy Individuals Frequently Exceed Tracheomalacia Diagnostic Criterion at CT
CT findings reveal that healthy volunteers frequently exceed the current diagnostic criterion (>50% expiratory reduction in cross-sectional area) for tracheomalacia, a disorder characterized by excessive expiratory collapse of tracheal walls and/or supporting cartilage. In 51 healthy volunteers, Boiselle and colleagues found that 78% exceeded the criterion in the upper and/or lower trachea. However, they also observed in only one volunteer a frownlike configuration of the trachea, which has previously been associated with tracheomalacia. Healthy individuals demonstrate a wide range of forced expiratory tracheal collapse, and a more rigorous diagnostic criterion is needed to prevent overdiagnosis of tracheomalacia, the researchers concluded.

Reduced ADC is a Predictor of Poor Outcome in Comatose Patients after Cardiac Arrest
Whole-brain diffusion-weighted MR may help predict recovery for patients in a comatose state after cardiac arrest. In a study of 80 patients, Wu and colleagues found that a severe reduction in apparent diffusion coefficient (ADC) was a significant predictor of poor outcome as measured by no eye opening or a 6-month modified Rankin scale score greater than 3. Multivariate analysis of ADC values in the occipital and parietal lobes and the putamen increased sensitivity in predicting poor outcome. Spatial and temporal differences in ADCs may provide insight into mechanisms of hypoxic-ischemic brain injury after cardiac arrest and, hence, recovery for comatose patients.

Optimal Positioning Can Reduce Radiation Dose Increases in Obese Patients
Radiation dose to obese patients can be substantially reduced with positioning techniques. Yanch and colleagues compared radiographic findings in "lean" reference phantoms and phantoms with added subcutaneous adipose tissue and reported that effective radiation doses can exceed 100 mSv after only a small number of radiographic examinations in extremely obese patients. Positioning the patient so that the thickest fat layer was facing the x-ray tube was effective in substantially reducing the dose. Increasing the tube voltage also reduced dose, but to a lesser extent. The researchers propose monitoring dose data for obese patients and recommend carefully considering patient orientation during examinations to limit increased dose to patients with more body fat.