Manganese (Mn(2+)) was recognized early as an efficient intracellular MR contrast agent to assess cardiomyocyte viability. It had previously been used for the assessment of myocardial infarction in various animal models from pig to mouse. However, whether Manganese-Enhanced MRI (MEMRI) is also able to assess infarction in the acute phase of a coronary occlusion reperfusion model in mice has not yet been demonstrated. This model is of particular interest as it is closer to the situation encountered in the clinical setting. This study aimed to measure infarction volume taking TTC staining as a gold standard, as well as global and regional function before and after Mn(2+) injection using a clinical 3T scanner. The first step of this study was to perform a dose-response curve in order to optimize the injection protocol. Infarction volume measured with MEMRI was strongly correlated to TTC staining. Ejection fraction (EF) and percent wall thickening measurements allowed evaluation of global and regional function. While EF must be measured before Mn(2+) injection to avoid bias introduced by the reduction of contrast in cine images, percent wall thickening can be measured either before or after Mn(2+) injection and depicts accurately infarct related contraction deficit. This study is the first step for further longitudinal studies of cardiac disease in mice on a clinical 3T scanner, a widely available platform. Copyright (c) 2010 John Wiley & Sons, Ltd.

Introduction: Planification of living donor nephrectomy requires exact knowledge of the renal vascular architecture because of the high prevalence of anatomical variants. After magnetic resonance angiography (MRA) challenged CT angiography for preoperative assessment over the last years, we revisit in this study the reliability of MRA as the sole preoperative assessment for living donor nephrectomy. Method: We compared the radiological findings of MRA performed as the sole radiological procedure in 44 living kidney donors with perioperative anatomy to verify its sensitivity and to validate its systematic use in the preoperative assessment for living donor nephrectomy. Results: 22 anatomical variants were found in 16 patients (16/44 = 36%). In 4 patients, a polar artery (3 superior, 1 inferior) was not seen by MRA and was detected during surgery (open nephrectomy). Supposing the anatomical variants it described on the opposite side of the nephrectomy are real, sensitivity of this technique in this series is 40/44 (91%) for arterial and 100% for venous imaging. Conclusion: MRA as the sole radiological preoperative assessment performed by a single radiologist with specific expertise and preoperatively reviewed with the harvesting surgeon has been validated as the sole radiological preoperative assessment for living donor nephrectomy at our institution.

Aims To evaluate the feasibility of loading resting monocytes/macrophages by intravenous (i.v.) injection of fluorescent iron oxide nanoparticles prior to injury and tracking of these cells in the very same animal to myocardial infarction (MI) by magnetic resonance imaging (MRI) and optical imaging. Methods and results Rats were injected with fluorescent iron oxide nanoparticles (10 mg/kg)(n = 15) prior to injury. After disappearance of the nanoparticles from the blood, MI was induced. Monocytes/macrophages were then tracked in the very same animal by MRI and optical imaging. Control groups were (i) non-injected animals (n = 15),(ii) injected animals associated with a sham operation (n = 8), and (iii) animals treated with an anti-inflammatory agent (n = 6). The presence of iron-loaded cells can be detected by MRI in vivo in the infarcted myocardium. Here, we showed that the detection of inflammatory cells in vivo correlated well with ex vivo imaging (MRI and reflectance fluorescence) and histology. We also showed that the method is robust enough to depict changes in the inflammatory response. Conclusion This study demonstrates that resting monocytes/macrophages can be loaded in vivo by a simple i.v. injection of fluorescent superparamagnetic iron oxide nanoparticles prior to injury and then tracked, in the same animal, in a model of ischaemia-reperfusion leading to myocardial infarct. Although previous studies of macrophages infiltration following MI have labelled the macrophages after injury, this study, for the first time, has pre-load the resting monocytes with fluorescent iron oxide nanoparticles.

Real-time cardiac MRI appears as a promising technique to evaluate the mechanical function of the heart. However, ultra-fast MRI acquisitions come with an important signal-to-noise ratio (SNR) penalty, which drastically reduces the image quality. Hence, a real-time denoising approach would be desirable for SNR amelioration. In the clinical context of cardiac dysfunction assessment, long acquisitions are required and for most patients the acquisition takes place with free breathing. Hence, it is necessary to compensate respiratory motion in real-time. In this article, a real-time and interactive method for sequential registration and denoising of real-time MR cardiac images is presented. The method has been experimented on 60 fast MRI acquisitions in five healthy volunteers and five patients. These experiments assessed the feasibility of the method in a real-time context.

BACKGROUND: To evaluate the diagnostic value of magnetic resonance imaging (MRI) of myocardial perfusion in the assessment of flow-limiting epicardial stenosis in a head-to-head comparison with abnormal thallium-201 ((201)TI) single photon emission tomography (SPECT) studies in patients with predominantly known coronary artery disease (CAD). METHODS AND RESULTS: Twenty-one patients (mean age 65 +/- 10 years) with reversible myocardial perfusion defects on (201)TI-SPECT images during dipyridamole-stimulated hyperemia were recruited for study purpose. Within 5 days of the (201)TI-SPECT study, myocardial perfusion was studied again with MRI during dipyridamole stimulation and at rest. Overall,(201)TI-SPECT identified 30 reversible regional perfusion defects. The sensitivity to detect hypoperfused segments was 70%(21/30) with the GRE-MRI perfusion analysis with (201)TI-SPECT as reference. When patients were subgrouped according to the extent of regional reversible perfusion defects on (201)TI-SPECT, mild-(SDS: 2-4), moderate-(SDS: 5-8), and severe-(SDS > 8) perfusion defects were also identified by GRE-MRI perfusion analysis in 75%(6/8), in 56%(9/16) and 100%(6/6), respectively. CONCLUSIONS: GRE-MRI first-pass stress perfusion imaging may not identify up to 30% of mild-to-moderate perfusion defects in a group of preselected patients with predominantly known CAD and abnormal (201)TI-SPECT studies.

Immunochemical faecal occult blood tests (I-FOBT) detect more effectively advanced neoplasia than guaiac tests (G-FOBT). The study aim was to compare the performance of an I-FOBT whilst varying the positivity threshold and considering four analysis modalities: one sample was performed (MG(1)), two samples were performed and at least one sample was positive (MG(2+)), both samples were positive (MG(2++)) or the mean of the two samples' log-transformed haemoglobin contents exceeded the cutoff (MG(2m)). Screening for colorectal cancer using both G-FOBT and two samples' I-FOBT was performed by an average-risk population sample of 20,322 subjects. Among the 1,615 subjects with at least one positive test, 1,277 had a satisfactory colonoscopy result; 43 invasive cancers and 270 high-risk adenomas were detected. The I-FOBT was reinterpreted under each analysis modality (a random selection of one sample led to MG(1)). For all modalities, increasing the positivity threshold decreased sensitivity and increased specificity. The relative ROC curves (in reference to G-FOBT) demonstrated similar performance for MG(1) and MG(2+), and improved performance for MG(2m). MG(2++) sensitivity was limited within the range of positivity thresholds evaluated. For any specificity, MG(2m) provided the highest sensitivity. For any sensitivity, MG(2m) provided the highest specificity. For any positivity rate, MG(2m) provided both the highest sensitivity and specificity. This study suggests the replacement of MG(2+) by MG(1) or, for even better performance, by MG(2m) provided that two samples are performed with similar participation (which should be explored). The targeted positivity rate could then be achieved by choosing the positivity threshold.(c) 2009 UICC.

INTRODUCTION: Marginal kidneys must be reanimated before their transplantation. Reanimation is conducted with hypothermic pulsatile perfusion. The tests used generally to demonstrate the viability is the vascular resistance which is not convenient for everybody. We have developed a magnetic resonance compatible perfusional technology allowing us to test the organs during the perfusion by Gd-perfusion MRI. METHODS AND RESULTS: We have used pigs' kidneys with no warm ischemic time to establish the basis in a normal kidney. After an eight-hour hypothermic pulsatile perfusion, kidneys are submitted to a Gd perfusion. First, we measure the anatomy of the vessels, then the distribution of Gd in the kidney. We obtain simultaneously a dynamic study of the organs where T0 represents the Gd bolus arrival in the cortex and TP the maximum saturation time of Gd. CONCLUSION: We have observed that a normal T0 is inferior to 30s and TP is inferior to one minute. We have compared these values with ATP resynthesis in these organs and found that they correlate. We hope for the future through that predictive use of Gd-MRI to avoid the clinical use of "too" marginal kidneys or the discard of good kidneys but not corresponding with the vascular resistance theory.

We investigated variations in sensitivity of an immunochemical (I-FOBT) and a guaiac (G-FOBT) faecal occult blood test according to type and location of lesions in an average-risk 50- to 74-year-old population. Screening for colorectal cancer by both non-rehydrated Haemoccult II G-FOBT and Magstream I-FOBT was proposed to a sample of 20 322 subjects. Of the 1615 subjects with at least one positive test, colonoscopy results were available for 1277. A total of 43 invasive cancers and 270 high-risk adenomas were detected. The gain in sensitivity associated with the I-FOBT was calculated using the ratio of sensitivities (RSN) according to type and location of lesions, and amount of bleeding. The gain in sensitivity by using I-FOBT increased from invasive cancers (RSN=1.48 (1.16-4.59)) to high-risk adenomas (RSN=3.32 (2.70-4.07)), and was inversely related to the amount of bleeding. Among cancers, the gain in sensitivity was confined to rectal cancer (RSN=2.09 (1.36-3.20)) and concerned good prognosis cancers, because they involve less bleeding. Among high-risk adenomas, the gain in sensitivity was similar whatever the location. This study suggests that the gain in sensitivity by using an I-FOBT instead of a G-FOBT greatly depends on the location of lesions and the amount of bleeding. Concerning cancer, the gain seems to be confined to rectal cancer.British Journal of Cancer advance online publication, 31 March 2009; doi:10.1038/sj.bjc.6604996 www.bjcancer.com.

ABSTRACT: BACKGROUND: The purpose of this study was to measure regional contractile function in the normal rat using cardiac cine and tagged cardiovascular magnetic resonance (CMR) during incremental low doses of dobutamine and at rest. METHODS: Five rats were investigated for invasive left ventricle pressure measurements and five additional rats were imaged on a clinical 1.5T MR system using a cine sequence (11-20 phases per cycle, 0.28/0.28/2 mm) and a C-SPAMM tag sequence (18-25 phases per cycle, 0.63/1.79/3 mm, tag spacing 1.25 mm). For each slice, wall thickening (WT) and circumferential strains (CS) were calculated at rest and at stress (2.5, 5 and 10 ug/min/kg of dobutamine). RESULTS: Good cine and tagged images were obtained in all the rats even at higher heart rate (300-440 bpm). Ejection fraction and left ventricular (LV) end-systolic volume showed significant changes after each dobutamine perfusion dose (p<0.001). Tagged CMR had the capacity to resolve the CS transmural gradient and showed a significant increase of both WT and CS at stress compared to rest. Intra and interobserver study showed less variability for the tagged technique. In rats in which a LV catheter was placed, dobutamine produced a significant increase of heart rate, LV dP/dtmax and LV pressure significantly already at the lowest infusion dose. CONCLUSION: Robust cardiac cine and tagging CMR measurements can be obtained in the rat under incremental dobutamine stress using a clinical 1.5T MR scanner.

The aim of this study was to measure the myocardial area at risk in rat, using MRI and manganese injection during a coronary occlusion/reperfusion model at 1.5T. A sequential protocol with occlusion and MnCl(2) injection immediately followed by MRI was used with the assumption that MnCl(2)-induced contrast persistence is enough to accurately image the area at risk 90 min after occlusion. A total of 15 adult rats underwent a single 30-min episode of coronary occlusion followed by reperfusion. MnCl(2) was injected (25 mumol/kg) at the beginning of the occlusion for 11 rats (group 1) and 6 h after reperfusion for four animals (group 2). A deficit of signal enhancement was observed in all rats. Hypoenhancement area in group 1 was correlated to the area at risk delineated by methylene blue (r = 0.96, P < 0.0001) whereas in group 2 it was correlated to the infarct area given by triphenyltetrazolium chloride (TTC) solution (r = 0.98, P = 0.003). The area at risk size was significantly correlated with left ventricle ejection fraction (LVEF), end-systolic volume and anterolateral wall thickening. This work demonstrates that hypoenhanced zone obtained after manganese injection during occlusion represents the area at risk and not only the infarct zone. Magn Reson Med 59:1422-1430, 2008.(c) 2008 Wiley-Liss, Inc.