Studying variability in human brain aging in a population-based German cohort-rationale and design of 1000BRAINS.

The ongoing 1000 brains study (1000BRAINS) is an epidemiological and neuroscientific investigation of structural and functional variability in the human brain during aging. The two recruitment sources are the 10-year follow-up cohort of the German Heinz Nixdorf Recall (HNR) Study, and the HNR MultiGeneration Study cohort, which comprises spouses and offspring of HNR subjects. The HNR is a longitudinal epidemiological investigation of cardiovascular risk factors, with a comprehensive collection of clinical, laboratory, socioeconomic, and environmental data from population-based subjects aged 45-75 years on inclusion. HNR subjects underwent detailed assessments in 2000, 2006, and 2011, and completed annual postal questionnaires on health status. 1000BRAINS accesses these HNR data and applies a separate protocol comprising: neuropsychological tests of attention, memory, executive functions and language; examination of motor skills; ratings of personality, life quality, mood and daily activities; analysis of laboratory and genetic data; and state-of-the-art magnetic resonance imaging (MRI, 3 Tesla) of the brain. The latter includes (i) 3D-T1- and 3D-T2-weighted scans for structural analyses and myelin mapping; (ii) three diffusion imaging sequences optimized for diffusion tensor imaging, high-angular resolution diffusion imaging for detailed fiber tracking and for diffusion kurtosis imaging; (iii) resting-state and task-based functional MRI; and (iv) fluid-attenuated inversion recovery and MR angiography for the detection of vascular lesions and the mapping of white matter lesions. The unique design of 1000BRAINS allows: (i) comprehensive investigation of various influences including genetics, environment and health status on variability in brain structure and function during aging; and (ii) identification of the impact of selected influencing factors on specific cognitive subsystems and their anatomical correlates.

Statistical evaluation of diffusion-weighted imaging of the human kidney.

The signal of diffusion-weighted imaging of the human kidney differs from the signal in brain examinations due to the different microscopic structure of the tissue. In the kidney, the deviation of the signal behavior of monoexponential characteristics is pronounced. The aim of the study was to analyze whether a mono- or biexponential or a distribution function model fits best to describe diffusion characteristics in the kidney. To determine the best regression, different statistical parameters were utilized: correlation coefficient (R(2)), Akaike's information criterion, Schwarz criterion, and F-test (F(ratio)). Additionally, simulations were performed to analyze the relation between the different models and their dependency on signal noise. Statistical tests showed that the biexponential model describes the signal of diffusion-weighted imaging in the kidney better than the distribution function model. The monoexponential model fits the diffusion-weighted imaging data the least but is the most robust against signal noise. From a statistical point of view, diffusion-weighted imaging of the kidney should be modeled biexponentially under the precondition of sufficient signal to noise.

The relation of regional cerebral perfusion and atrophy in mild cognitive impairment (MCI) and early Alzheimer's dementia.

The spatial and temporal relations between regional cerebral blood flow (rCBF) and brain volume (rVOL) changes in incipient and early Alzheimer's dementia (AD) are not fully understood. The participants comprised 30 subjects with mild cognitive impairment (MCI) and 15 with mild AD who were examined using structural and perfusion-weighted magnetic resonance imaging (MRI) at 1.5 Tesla. Hippocampus and amygdala volumes were measured by manual volumetry. A region-of-interest co-localisation method was used to calculate rCBF values. DNA samples were genotyped for apolipoprotein E (APO E). In comparisons of AD with MCI, rCBF was reduced in the posterior cingulum only, while profound rVOL reductions occurred in both right and left amygdala and in the right hippocampus, and as a trend, in the left hippocampus. Brain volumes of the hippocampus and the amygdala were uncorrelated with the respective rCBF variables in both MCI and AD. Hippocampal but not amygdalar volumes were associated with presence of one or two APOE epsilon4 alleles in MCI and mild AD, while there was no association of APOE epsilon4 allele with rCBF. These data support earlier indications that rCBF and rVOL changes are at least partly dissociated in the early pathogenesis of AD and heterogeneously associated with the APOE risk allele. The data also support the concept of functional compensatory brain activation and the diaschisis hypothesis as relevant in incipient and early AD.

MRI morphometry, cartilage damage and impaired function in the follow-up after slipped capital femoral epiphysis.

OBJECTIVE: To assess rotation deficits, asphericity of the femoral head and localisation of cartilage damage in the follow-up after slipped capital femoral epiphysis (SCFE). MATERIALS AND METHODS: Magnetic resonance imaging studies were obtained in adult patients with a history of SCFE. A total of 35 hips after SCFE in 26 patients (mean age 24.1 +/- 6.5, mean follow-up 11.9 +/- 6.1 years) were evaluated. The control group comprised 20 healthy hips from 10 young adults with an average age of 23.9 +/- 3.7 years. The MR protocol included a T1-weighted sequence with a 3D volumetric interpolated breath-hold sequence and a radial 2D proton density-weighted sequence around the femoral neck. Images were evaluated for alpha angle and cartilage damage in five positions around the femoral head. Hip function was evaluated at the time of MRI and correlated with MRI results. Mann-Whitney U test and Spearman's correlation coefficient were used for statistical analysis. RESULTS: In the hips after SCFE alpha angles were significantly increased in the anterosuperior (74.1 degrees +/- 18.8 degrees ) and superior (72.5 degrees +/- 21.5 degrees ) positions and decreased in the posterior position (25.0 degrees +/- 7.2 degrees ). Cartilage damage was dominant in the anterosuperior and superior positions. Impaired rotation significantly correlated with increased anterosuperior, superior and posterosuperior alpha angles. CONCLUSION: The data support an anterosuperior and superior cam-type deformity of the femoral head-neck junction in the follow-up after SCFE. MRI after SCFE can be used to assess anterosuperior and superior alpha angles, since the anterior alpha angle by itself may underestimate asphericity and is not associated with rotation deficits.

Image quality and bile duct volumetry in MR cholangiopancreatography augmented with low-dose morphine.

OBJECTIVE: Opioids are applied to augment visualization of the biliary system in MR cholangiopancreatography (MRCP) to take advantage of a side effect, the constriction of the sphincter of Oddi. This prospective study was performed to determine the effect of IV low-dose morphine on image quality and bile duct delineation in MRCP. SUBJECTS AND METHODS: Fifteen healthy volunteers and 15 consecutive patients underwent MRCP on a 1.5-T MRI scanner. Strongly T2-weighted 3D single-shot fast spin-echo (SSFSE) sequences were acquired before and 10 minutes after IV administration of morphine (0.04 mg/kg of body weight; mean +/- SD, 2.9 +/- 0.5 mg). Maximum intensity projections were reconstructed from the SSFSE sequence data. Image quality was rated by two independent radiologists using a 4-point scale (1 = excellent, 4 = not diagnostic). Delineation of segmental and subsegmental intrahepatic bile duct orders before and after morphine administration was compared. Volumetry of the common bile duct (CBD) was performed using electronic measurements (AngioTux software, ECCET image processing system). RESULTS: IV morphine did not significantly improve subjective image quality of the extra- and intrahepatic bile ducts (mean image quality score before vs after morphine administration, 2.3 vs 2.0) or delineation of the intrahepatic bile duct orders. The volume of the CBD remained constant after morphine administration (mean CBD volume before vs after morphine administration, 14.1 vs 13.6 mL). Notable side effects of morphine were seen in two young healthy female volunteers. CONCLUSION: IV-administered low-dose morphine seems to have no essential influence on image quality or delineation of the bile duct system in MRCP. Therefore, the general advice to perform morphine-augmented MRCP should be discussed critically.

Typical atypical findings on dynamic MRI of the breast.

Dynamic contrast enhanced magnetic resonance imaging (DCE MRI) of the breast has become an important tool to detect and characterize breast disease. The American College of Radiology Breast Imaging Reporting and Data System (BI-RADS(®)) provides a standardized vocabulary for describing the morphologic features and contrast kinetics of breast lesions. However, some lesions may show morphologic and dynamic MR features not consistent with their histologic nature resulting in incorrect categorization as malignant or benign. Another cause of diagnostic problems is artifacts. Thus correct interpretation of dynamic MRI of the breast demands knowledge of the most common pitfalls encountered in clinical practice. A pictorial overview of these is presented, with particular reference to the differentiation of malignant tumors from benign lesions.

Voxel-based analyses of magnetization transfer imaging of the brain in hepatic encephalopathy.

AIM: To evaluate the spatial distribution of cerebral abnormalities in cirrhotic subjects with and without hepatic encephalopathy (HE) found with magnetization transfer imaging (MTI). METHODS: Nineteen cirrhotic patients graded from neurologically normal to HE grade 2 and 18 healthy control subjects underwent magnetic resonance imaging. They gave institutional-review-board-approved written consent. Magnetization transfer ratio (MTR) maps were generated from MTI. We tested for significant differences compared to the control group using statistical non-parametric mapping (SnPM) for a voxel-based evaluation. RESULTS: The MTR of grey and white matter was lower in subjects with more severe HE. Changes were found in patients with cirrhosis without neurological deficits in the basal ganglia and bilateral white matter. The loss in magnetization transfer increased in severity and spatial extent in patients with overt HE. Patients with HE grade 2 showed an MTR decrease in white and grey matter: the maximum loss of magnetization transfer effect was located in the basal ganglia [SnPM (pseudo-)t = 17.98, P = 0.0001]. CONCLUSION: The distribution of MTR changes in HE points to an early involvement of basal ganglia and white matter in HE.

Prospective randomized trial of operative vs interventional treatment for renal artery ostial occlusive disease (RAOOD).

INTRODUCTION AND OBJECTIVES: Patients with either renovascular hypertension (RVH) and/or renal insufficiency (RI) due to renal artery ostial occlusive disease (RAOOD) can successfully undergo an open surgical reconstruction procedure (OSRP), but since the publication of Blum et al(1) percutaneous balloon stent angioplasty (PTRA + stent) leaving a small part of the stent within the aorta has become very popular. However, balloon dilatation and stenting does not remove the atherosclerotic plaque, which is often heavily calcified but leads to disruption of the plaque causing myointimal hyperplasia and recurrent stenosis. Therefore, a comparison of the two treatment modalities concerning complications and durability in a prospective randomized design was felt to bring more insight to the discussion. METHODS: From 1998 to 2004, we performed OSRP in 330 patients with RVH and/or RI for various locations of RAOOD. During this time period, 50 patients (female 18, male 32, mean age 64.4 years) with RAOOD of at least 70% stenosis (DSA and duplex criteria) in one or both renal arteries, who did not require other aorto/mesenteric/iliac reconstructive procedures agreed and were randomized to either OSRP (n = 25 patients, 49 arteries) or PTRA + stent (n = 25 patients, 28 arteries). Two patients crossed over to surgical treatment. Patients were followed on a regular basis for 4 years and longer. Endpoints were re-occurrence of RAOOD and impairment of either kidney function or RVH. RESULTS: We approached 77 arteries. There was no early mortality in either group, but directly procedure-related morbidity was 13% in the interventional group and 4% in the surgical group. Four-year follow-up mortality was 18% in the interventional group and 25% in the surgical group. Both groups showed significant improvement of RVH (P < .001 in each group) as well as improvement or stabilization in patients with insufficient renal function. Freedom from recurrent RAOOD (>70%) was achieved in 90.1% of the surgical group and 79.9% of the interventional group. CONCLUSION: Both treatment modalities showed good early results concerning RVH, kidney function, and renal perfusion. Despite a higher number of bilateral renal artery reconstructions in patients undergoing OSRP, which was probably due to the preferred technique of transaortic endarterectomy eliminating the plaque originating in the aorta and usually extending into both renal arteries, mortality was not higher and procedure-related morbidity was even lower compared to PTRA + stent. These findings and also longer durability of OSRP imply that surgical reconstruction remains the gold standard for patients with RAOOD before PTRA + stent may be considered.

Myocardial delayed contrast enhancement in patients with arterial hypertension: initial results of cardiac MRI.

PURPOSE: In arterial hypertension left ventricular hypertrophy comprises myocyte hypertrophy, interstitial fibrosis and structural alterations of the coronary microcirculation. MRI enables the detection of myocardial fibrosis, infarction and scar tissue by delayed enhancement (DE) after contrast media application. Aim of this study was to investigate patients with arterial hypertension but without known coronary disease or previous myocardial infarction to detect areas of DE. METHODS AND MATERIAL: Twenty patients with arterial hypertension with clinical symptoms of myocardial ischemia, but without history of myocardial infarction and normal coronary arteries during coronary angiography were investigated on a 1.0 T superconducting magnet (Gyroscan T10-NT, Intera Release 8.0, Philips). Fast gradient-echo cine sequences and T2-weighted STIR-sequences were acquired. Fifteen minutes after injection of Gadobenate dimeglumine inversion recovery gradient-echo sequences were performed for detection of myocardial DE. Presence or absence of DE on MRI was correlated with clinical data and the results of echocardiography and electrocardiography, respectively. RESULTS: Nine of 20 patients showed DE in the interventricular septum and the anteroseptal left ventricular wall. In 6 patients, DE was localized intramurally and in 3 patients subendocardially. There was a significant correlation between myocardial DE and ST-segment depressions during exercise and between DE and left-ventricular enddiastolic pressure. Patients with intermittent atrial fibrillation showed a myocardial DE more often than patients without atrial fibrillation. CONCLUSION: In our series, 45% of patients with arterial hypertension showed DE on cardiac MRI. In this clinical setting, delayed enhancement may be due to coronary microangiopathy. The more intramurally localization of DE, however, rather indicates myocardial interstitial fibrosis.

Detection of changed regional cerebral blood flow in mild cognitive impairment and early Alzheimer's dementia by perfusion-weighted magnetic resonance imaging.

The utility of perfusion-weighted magnetic resonance imaging (PW-MRI) for detecting changes in regional cerebral blood flow (rCBF) in patients with mild cognitive impairment (MCI) and early Alzheimer's disease (AD) was evaluated. Thirteen cognitively normal (CN) elderly subjects, 35 mostly amnestic MCI subjects and 20 subjects with mild probable AD were enrolled. During i.v. injection of gadopentetate dimeglumine, a dynamic T2*-weighted single-shot EPI sequence was conducted using a 1.5-T scanner. Frontobasal (FROB), temporoparietal (TPAR), mesiotemporal (MTMP), anterior and posterior cingular (ACING, PCING), amygdala (AMYG), thalamus and cerebellar brain regions were studied. rCBF was computed from regional cerebral blood volume and arterial input function and normalised to white matter. Images were analysed by manually placed regions of interest using anatomical coregistration. Significant decreases of rCBF were detected in MCI vs. CN in MTMP (-23%), AMYG (-20%) and ACING (-15%) with no further decline in mild AD. In PCING hypoperfusion (-10%) was confined to AD. These hypoperfusional changes are a possible correlate of localised impairment of CNS function. In FROB no perfusion changes were observed between diagnostic groups, but hyperperfusion was observed in mild dementia stages, possibly reflecting functional compensatory mechanisms. These data suggest that PW-MRI detects specific changes in rCBF not only in AD, but also in amnestic MCI, a disorder suggested to largely represent a pre-dementia stage of AD. This method may thus be useful in both research and clinical applications to detect early functional brain changes in the pathogenesis of dementias.

Minimally invasive therapy of pseudoaneurysms of the trunk: application of thrombin.

Thrombin injection has been proven to be successful in postcatheterization pseudoaneurysms. However, there are only a few reports on the treatment of pseudoaneurysms of the trunk. We report our first experiences using a percutaneous as well as an endovascular access. Eight iatrogenic pseudoaneurysms of the trunk (aorta, n = 4; pulmonary artery, n = 1; gastroduodenal artery, n = 1; left gastric artery, n = 1, renal artery, n = 1) were treated either percutaneously using CT guidance (n = 3) or via an endovascular access (n = 5). Noninvasive control angiograms were performed at day 1 and weeks 1 and 3 by either CT or MR angiography. The total volume of the pseudoaneurysms was 31.2 +/- 23.1 ml on average, with a mean volume of the perfused aneurysmal lumen of 12.9 +/- 7.2 ml. The maximum diameter was 4.1 +/- 1.39 cm on average. In each case, the aneurysmal neck was not wider than 2 mm. One pseudoaneurysm occluded spontaneously following selective catheterization. The remaining pseudoaneurysms were successfully treated by injection of 765 +/- 438.1 IU thrombin. In one individual, a nontarget embolization occurred, as well as an intervention-associated rupture of a pseudoaneurysm. High-grade stenoses of the donor artery were found in a different case. Only once was the endoluminal access converted to a percutaneous one. Thrombin injection might be a future first-line treatment of vascular lesions such as pseudoaneurysms of the trunk. In our experience both percutanous and endoluminal access are technically feasible and safe. However, further experiences are mandatory, especially concerning the question of dosage and long-term results.

Comparison of whole-body 64-slice multidetector computed tomography and conventional radiography in staging of multiple myeloma.

This study compares the sensitivity of whole-body multidetector CT (MDCT) and conventional radiography (CR) in the staging of multiple myeloma (MM). Twenty-nine patients with MM underwent a staging examination both by MDCT and CR. CT examination was performed with a collimation of 64x0.6 mm, a tube potential of 100 kVp, an effective tube current-time product of 100 mAs and automatic dose modulation as low-dose protocol. Number, size and diagnostic confidence of osteolytic lesions were determined and compared. The effective dose of MDCT and CR was assessed. Using MDCT, the detection of osteolysis was increased seven-fold concerning the spine. Ninety-seven lesions in 18 patients were detected exclusively by MDCT. The detection rate concerning the spine, pelvic skeleton and thoracic cage was significantly higher (p< or =0.001), and diagnostic confidence was increased by MDCT (p<0.02) compared to CR. Therapy was changed after MDCT in 18.2% of the patients with a clinical suspicion of progressive disease. The estimated effective dose of MDCT (4.8 mSv) and CR (1.7 mSv) was comparable. In conclusion, MDCT has a significantly higher sensitivity and reliability in the detection of osteolysis than CR and can be recommended as standard imaging method in the staging of MM.

Iron oxide particle-enhanced MRI suggests variability of brain inflammation at early stages after ischemic stroke.

BACKGROUND AND PURPOSE: Inflammation contributes to brain damage caused by ischemic stroke. Ultrasmall superparamagnetic iron oxide (USPIO)-enhanced MRI allows noninvasive monitoring of macrophage recruitment into ischemic brain lesions. In this study, we determined the extent of USPIO enhancement during early stages of ischemic stroke. METHODS: Twelve consecutive patients with typical clinical signs of stroke underwent multimodal stroke imaging at 1.5-T within 24 hours of symptom onset. They received intravenous USPIO (ferumoxtran) infusion at 26 to 96 hours (mean, 44 hours) after stroke. A total of four follow-up MRI scans were performed 24 to 36 hours, 48 to 72 hours, 7 to 8 days, and 10 to 11 days after USPIO infusion. RESULTS: Nine patients were included in the final analysis. Parenchymal USPIO enhancement occurred in 3 of 9 analyzed patients and was mainly evident on T1-weighted spin-echo images. USPIO-dependent signal changes were spatially heterogeneous, reflecting the distinct patterns of hematogenous macrophage infiltration in different lesion types. CONCLUSIONS: Our findings suggest a variable extent and distribution of macrophage infiltration into early ischemic stroke lesions. USPIO-enhanced MRI may help to more specifically target antiinflammatory therapy in patients with stroke.

Dynamic breast MR imaging: is parametric mapping superior to image subtraction in lesion detection?

We compared the detection of malignant lesions in two different methods of parametric-guided analysis to the widely used early subtraction images. The parametric colour-coded overlays were defined by the increase of signal intensity after contrast injection and the course of the time signal intensity curve. Exams of 30 patients with histopathological evidence of 32 invasive breast carcinomas were evaluated. Five hundred five areas of additional enhancing tissue were found in the early subtraction images. The sensitivity was 100 in the subtraction images and 100 and 93.8 in the parametric images, respectively, the specificity 67.5, 84.2 and 88.7, respectively. On average 4.4 ROI-measurements were needed to find the highest increase of signal intensity in the subtraction series compared to 1.9 in the parametric images. Properly selected thresholds in parametric imaging may be helpful in the differentiation of enhancing tissue. Furthermore the parametric image-guided ROI selection significantly speeds up the analysis and makes it safer as a lower rate of ROI-measurements is needed to find the strongest enhancement.

Portal vein embolization and autologous CD133+ bone marrow stem cells for liver regeneration: initial experience.

PURPOSE: To prospectively evaluate the effectiveness of portal vein embolization (PVE) and CD133(+) bone marrow stem cell (BMSC) administration to the liver, compared with PVE alone, to augment hepatic regeneration in patients with large hepatic malignancies. MATERIALS AND METHODS: The study was approved by the institutional ethics committee; informed consent was obtained. Thirteen patients underwent PVE of liver segments I and IV-VIII to stimulate hepatic regeneration prior to extended right hepatectomy. In six patients (three men, three women; mean age, 61 years; range, 46-72 years) with a future liver remnant volume (FLRV) below 25% and/or limited quality of hepatic parenchyma, PVE alone did not promise adequate proliferation. These patients underwent BMSC administration to segments II and III (group I). In seven patients (three men, four women; mean age, 69 years; range, 63-75 years) with an FLRV below 25%, PVE alone was performed (group II). Two radiologists blinded to patients' identity and each other's results measured liver and tumor volumes with helical computed tomography. Absolute, relative, and daily FLRV gains were compared by using the t test or the Wilcoxon test. RESULTS: The increase of the mean absolute FLRV in group I from 239.3 mL +/- 103.5 (standard deviation) to 417.1 mL +/- 150.4 was significantly higher than that from 286.3 mL +/- 77.1 to 395.9 mL +/- 94.1 in group II (P = .049). The relative gain of FLRV after PVE in group I (77.3% +/- 38.2) was significantly higher than that in group II (39.1% +/- 20.4) (P = .039). The daily hepatic growth rate in group I (9.5 mL/d +/- 4.3) was significantly superior to that in group II (4.1 mL/d +/- 1.9) (P = .03). Time to surgery was 27 days +/- 11 in group I and 45 days +/- 21 in group II (P = .057). CONCLUSION: In patients with malignant liver lesions, the combination of PVE with CD133(+) BMSC administration substantially increased hepatic regeneration compared with PVE alone.

Hyperbaric oxygen for adjuvant therapy for chronically recurrent mandibular osteomyelitis in childhood and adolescence.

PURPOSE: In this article, the question of whether adjuvant hyperbaric oxygen therapy (HBO) has a positive effect when treating chronically recurrent mandibular osteomyelitis in children and adolescents is discussed. PATIENTS AND METHODS: Over a period of 5 years, 4 cases were observed, 3 of which were submitted to adjuvant HBO. Details on the modalities of this type of treatment and the simultaneous intravenous administration of high doses of antibiotics are reported. RESULTS: All 3 patients have been free of any symptoms from 20 to 74 months (mean, 41 months) and therefore may most likely be regarded as healed. CONCLUSION: The small number of cases does not allow a final statement on the extent to which HBO contributed to the positive outcome. However, in our opinion, HBO is a most promising therapeutic option. Finally, the problems involved in prospective randomized studies of this rare disease are discussed in detail.

Duplex ultrasound and renin ratio predict treatment failure after revascularization for renal artery stenosis.

BACKGROUND: The aim of this study was to find predictors to identify patients with hypertension who will not improve after removal of renal artery stenosis (RAS). METHODS: Prospective study of patients with unilateral stenosis (>60% diameter reduction) and hypertension in 24-h measurements despite antihypertensive drugs, who underwent revascularization (surgery/angioplasty). Examinations were performed before treatment and after 3 and 6 months after exclusion of restenosis. Studies included 24-h blood pressure, creatinine clearance, 99Tc MAG3 scintigraphy, and measurements of renal vein plasma renin activity (PRA). Intrarenal resistance indices (RI) were determined with duplex ultrasound before and 30 min after administration of intravenous enalaprilat. Improvement of hypertension was defined by a score consisting of 24-h mean arterial pressure and the number of antihypertensive drugs. RESULTS: From December 2000 to December 2003, 50 patients completed the study. Improvement of hypertension was observed in 18 patients (36%). Comparison between responders (n = 18) and nonresponders (n = 32) revealed significant differences only for RI and PRA measurements. The largest area under the curve in receiver-operating characteristic (ROC) analysis for prediction of no improvement of hypertension was found for RI (stenosis side), which was nearly identical for measurements before and after administration of angiotensin-converting enzyme (ACE) inhibitor. The highest sensitivities and specificities predicting which patients will not improve were found for RIs > or = 0.55. The highest univariate odds ratio (OR 44, confidence interval [CI] 4.8-404) was found for the parameters of RI > or = 0.55 and a renin ratio of <1:1.5. CONCLUSIONS: Resistance indices of the poststenotic kidney above 0.55 and a negative renin ratio can predict a poor outcome concerning arterial blood pressure response after restoration of renal blood flow for unilateral renal artery stenosis.

Positive effects of nitric oxide on left ventricular function in humans.

AIMS: The myocardial effect of tonically released nitric oxide (NO) in humans is still not known. We tested the hypothesis that low-dose NO exerts positive effects on left ventricular (LV) function. METHODS AND RESULTS: Twelve healthy volunteers, 26+/-4 years, were enrolled in this study. Magnetic resonance imaging was used to precisely measure the direct effects of NO on stroke volume index (SVI). The NO pool was monitored by chemiluminescence. We reduced endogenous NO levels with intravenous infusion of the NO synthase-inhibitor N(G)-monomethyl-l-arginine. Replenishment of the NO pool was achieved with the NO donor S-nitrosoglutathione (GSNO) (0.5 micromol iv). To differentiate load-dependent from the direct effects of NO on LV function, changes in SVI in response to GSNO were compared with changes in the NO-independent vasodilator dihydralazine (2.5 mg iv) at matched arterial pressure and heart rate. Inhibition of NO synthesis was followed by reduction in SVI. Subsequent replenishment of the circulating NO with GSNO significantly increased SVI (39+/-8 to 54+/-7 mL m(-2); P=0.001), whereas no significant changes were observed with the NO-independent vasodilator dihydralazine (39+/-8 to 46+/-8 mL m(-2); P=0.0626). CONCLUSION: Inhibition of endogenous NO release reduces, whereas replenishment with exogenous NO increases LV function, pointing towards a positive effect of tonically released NO on LV function in healthy humans.

Multi-detector CT-colonography in inflammatory bowel disease: prospective analysis of CT-findings to high-resolution video colonoscopy.

AIM: Prospective analysis of multi-detector CT-colonography (MDCTC) in patients with inflammatory bowel disease (IBD) compared to high-resolution video-endoscopy (HRVC). MATERIALS AND METHODS: Twenty-one patients (mean age 49.6 years) with Crohn's disease or ulcerative colitis underwent MDCTC (Somatom Volume Zoom, Siemens, Erlangen; 1mm collimation, Pitch 8, 100 mAs, 120 kVp). HRVC was performed within 2 h after MDCTC. MDCTC was analyzed by two blinded readers. MDCTC-findings including bowel wall alterations and extraintestinal changes were compared to results of HRVC. RESULTS: Over-all-sensitivity was 100% for endoluminal lesions with correct diagnosis of two cancers. Acute and chronic IBD were correctly identified by MDCTC in 63.6%, and 100%, respectively, with a specificity of 75%, and 100%. Sensitivity, specificity, positive and negative predictive values of MDCTC for diagnosis of acute and chronic disease were best for chronic disease. Sensitivity was worst for acute ulcerative colitis and specificity was worst for acute Crohn's disease. Haustral loss was seen only in ulcerative colitis. Pseudopolyps and fistulae were findings exclusive to Crohn's disease. Particularly extraintestinal findings as increased vascularization and local lymphadenopathy correlated well with endoscopic definition of acute disease. Because of the possibly more vulnerable colonic wall in acute inflammatory bowel disease, the air inflation for MDCTC should be performed most carefully to avoid any risk of colonic perforation. CONCLUSION: MDCTC may help to distinguish between patients with acute and chronic IBD. Especially extraintestinal complications, tumorous as well as pseudo-tumorous lesions can be detected with high sensitivity and specificity.