Radiation dose to conceptus resulting from tangential breast irradiation

PURPOSE: To estimate the radiation dose to the conceptus resulting from tangential breast irradiation. METHODS AND MATERIALS: Conceptus radiation doses were measured in anthropomorphic phantoms simulating the geometry of a pregnant woman at the first, second, and third trimesters of gestation. Medial and lateral field irradiations were generated using a 6-MV X-ray beam. Dose measurements were performed with thermoluminescent dosimeters. RESULTS: For a treatment course delivering 50 Gy to the tumor, conceptus dose at the first trimester of gestation was found to be 2.1-7.6 cGy, depending on the field size used and the distance between conceptus and primary irradiation field. The corresponding dose ranges to the conceptus during the second and third trimesters of gestation were 2.2-24.6 cGy and 2.2-58.6 cGy, respectively. Dose data and formulas are presented to estimate conceptus dose for individual patients undergoing breast radiotherapy during the entire pregnancy. CONCLUSIONS: This study may be of value in the management of pregnant women needing tangential breast irradiation, because it provides the required information to estimate conceptus dose.     

Contrast-enhanced magnetic resonance cholangiography versus heavily T2-weighted magnetic resonance cholangiography

RATIONALE AND OBJECTIVES: To investigate the feasibility of contrast-enhanced magnetic resonance cholangiography (CE-MRC) and compare it with single-shot turbo spin-echo magnetic resonance cholangiography (SSTSE-MRC). METHODS: Fifteen patients with suspected metastatic liver disease (n = 10) or biliary tree abnormalities (n = 5) underwent a magnetic resonance imaging (1.5-T system) examination before and after mangafodipir administration. Contrast-enhanced MRC with a three-dimensional fast low-angle shot sequence after mangafodipir trisodium administration was compared with SSTSE-MRC. Four anatomic segments were evaluated: the intrapancreatic and extrapancreatic common bile duct segments, the cystic duct, and the area of hepatic bifurcation. Contrast-enhanced MRC and SSTSE-MRC were separately analyzed on a 5-point grading scale in terms of ductal segment visualization and lumen narrowing or dilatation. RESULTS: There was no difference (P = 0.375) in segment visualization between CE-MRC and SSTSE-MRC; 56 of the 60 segments were visualized by both techniques. In the evaluation of ductal narrowing or dilatation, nonsignificant differences (P = 0.500) were observed. Contrast-enhanced MRC was not influenced by fluid superimposition and provided additional information from background tissues. CONCLUSIONS: Contract-enhanced MRC is a feasible technique showing anatomic correlation with SSTSE-MRC, and it can in addition provide functional information. Contrast-enhanced MRC may be used in selected patients when traditional SSTSE-MRC is inconclusive.     

Detection of colorectal cancer hepatic metastases with contrast-enhanced ultrasound: comparison with conventional B-mode ultrasound

The aim of this study was to assess whether contrast-enhanced ultrasound (CE-US) could provide improved diagnostic information in detecting liver metastases from colorectal cancer as compared to B-mode non-enhanced ultrasound (B-US). 32 patients (M/F 23/9, age range 48-82 years, mean 58.2 years) under chemotherapy for colorectal cancer were examined with B-US and CE-US using a second-generation ultrasound contrast agent and a dedicated protocol for contrast detection. The presence of focal liver lesions along with the number, size, pre- and post-contrast sonographic features were recorded digitally. Lesion conspicuity with a three-grade scoring scale was performed on both techniques and contrast intensity measurements were calculated for each focal lesion. CE-US detected 17% more metastases in patient-by-patient and lesion-by-lesion analysis. A statistically significant difference was found between the scoring mean values with regard to conspicuity of the lesions. Accurate characterization of the liver lesions was achievable only with contrast-enhanced technique. A quantitative contrast intensity measurement method confirmed the invariably washing-out vascular pattern in all metastases at sinusoidal-parenchymal liver phase. In conclusion, CE-US is superior to B-US and provides an effective tool in the investigation of colorectal cancer liver metastases.     

Chronic kidney disease and bone fracture: a growing concern

Susceptibility to fracture is increased across the spectrum of chronic kidney disease (CKD). Moreover, fracture in patients with end-stage kidney disease (ESKD) results in significant excess mortality. The incidence and prevalence of CKD and ESKD are predicted to increase markedly over the coming decades in conjunction with the aging of the population. Given the high prevalence of both osteoporosis and CKD in older adults, it is of the utmost public health relevance to be able to assess fracture risk in this population. Dual-energy X-ray absorptiometry (DXA), which provides an areal measurement of bone mineral density (aBMD), is the clinical standard to predict fracture in individuals with postmenopausal or age-related osteoporosis. Unfortunately, DXA does not discriminate fracture status in patients with ESKD. This may be, in part, because excess parathyroid hormone (PTH) secretion may accompany declining kidney function. Chronic exposure to high PTH levels preferentially causes cortical bone loss, which may be partially offset by periosteal expansion. DXA can neither reliably detect changes in bone volume nor distinguish between trabecular and cortical bone. In addition, DXA measurements may be low, normal, or high in each of the major forms of renal osteodystrophy (ROD). Moreover, postmenopausal or age-related osteoporosis may also affect patients with CKD and ESKD. Currently, transiliac crest bone biopsy is the gold standard to diagnose ROD and osteoporosis in patients with significant kidney dysfunction. However, bone biopsy is an invasive procedure that requires time-consuming analyses. Therefore, there is great interest in developing non-invasive high-resolution imaging techniques that can improve fracture risk prediction for patients with CKD. In this paper, we review studies of fracture risk in the setting of ESKD and CKD, the pathophysiology of increased fracture risk in patients with kidney dysfunction, the utility of various imaging modalities in predicting fracture across the spectrum of CKD, and studies evaluating the use of bisphosphonates in patients with CKD.     

Methodology and Evaluation of Intracranial Pressure Response in Rats Exposed to Complex Shock Waves

Studies on blast neurotrauma have focused on investigating the effects of exposure to free-field blast representing the simplest form of blast threat scenario without considering any reflecting surfaces. However, in reality personnel are often located within enclosures or nearby reflecting walls causing a complex blast environment, that is, involving shock reflections and/or compound waves from different directions. The purpose of this study was to design a complex wave testing system and perform a preliminary investigation of the intracranial pressure (ICP) response of rats exposed to a complex blast wave environment (CBWE). The effects of head orientation in the same environment were also explored. Furthermore, since it is hypothesized that exposure to a CBWE would be more injurious as compared to a free-field blast wave environment (FFBWE), a histological comparison of hippocampal injury (cleaved caspase-3 and glial fibrillary acidic protein (GFAP)) was conducted in both environments. Results demonstrated that, regardless of orientation, peak ICP values were significantly elevated over the peak static air overpressure. Qualitative differences could be noticed compared to the ICP response in rats exposed to simulated FFBWE. In the CBWE scenario, after the initial loading the skull/brain system was not allowed to return to rest and was loaded again reaching high ICP values. Furthermore, results indicated consistent and distinct ICP-time profiles according to orientation, as well as distinctive values of impulse associated with each orientation. Histologically, cleaved caspase-3 positive cells were significantly increased in the CBWE as compared to the FFBWE. Overall, these findings suggest that the geometry of the skull and the way sutures are distributed in the rats are responsible for the difference in the stresses observed. Moreover, this increase stress contributes to correlation of increased injury in the CBWE.     

Evolution of innate and adaptive effector cell functions during acute HIV-1 infection

Early events during acute human immunodeficiency virus type 1 (HIV-1) infection are critical in determining the course of disease progression. Cells of the innate and adaptive immune responses are involved in this acute response to infection; however, little is known about the coevolution of innate and adaptive effector cell populations during the initial phase of HIV-1 infection. Here, we have characterized the development of innate natural killer (NK) cell and adaptive HIV-1-specific CD8(+) T cell function during acute HIV-1 infection. Although NK cell populations were significantly expanded during acute infection before HIV-1 seroconversion, HIV-1-specific CD8(+) T cell responses were absent or weak and were inversely correlated with the level of NK cell activity. NK cell activity was directly correlated with the level of viral replication during acute HIV-1 infection and declined rapidly in subjects who initiated highly active antiretroviral therapy, whereas NK cell activity remained elevated in subjects who did not initiate therapy. Yet, reexposure to HIV-1 antigen during treatment discontinuation in chronic infection resulted in a synchronous increase in NK and CD8(+) T cell activity. Overall, these data demonstrate that expansion of the NK cell population precedes the development of adaptive HIV-1-specific CD8(+) T cells during acute infection but that both effector cell subsets respond with similar kinetics during chronic HIV-1 infection.