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Obtaining functional information on the human lung is of tremendous interest in the characterization of lung defects and pathologies. However, pulmonary ventilation and perfusion maps usually require contrast agents and the application of electrocardiogram (ECG) triggering and breath holds to generate datasets free of motion artifacts. This work demonstrates the possibility of obtaining highly resolved perfusion-weighted and ventilation-weighted images of the human lung using proton MRI and the SElf-gated Non-Contrast-Enhanced FUnctional Lung imaging (SENCEFUL) technique. The SENCEFUL technique utilizes a two-dimensional fast low-angle shot (FLASH) sequence with quasi-random sampling of phase-encoding (PE) steps for data acquisition. After every readout, a short additional acquisition of the non-phase-encoded direct current (DC) signal necessary for self-gating was added. By sorting the quasi-randomly acquired data according to respiratory and cardiac phase derived from the DC signal, datasets of representative respiratory and cardiac cycles could be accurately reconstructed. By application of the Fourier transform along the temporal dimension, functional maps (perfusion and ventilation) were obtained. These maps were compared with dynamic contrast-enhanced (DCE, perfusion) as well as standard Fourier decomposition (FD, ventilation) reference datasets. All datasets were additionally scored by two experienced radiologists to quantify image quality. In addition, one initial patient examination using SENCEFUL was performed. Functional images of healthy volunteers and a patient diagnosed with hypoplasia of the left pulmonary artery and left-sided pulmonary fibrosis were successfully obtained. Perfusion-weighted images corresponded well to DCE-MRI data; ventilation-weighted images offered a significantly better depiction of the lung periphery compared with standard FD. Furthermore, the SENCEFUL technique hints at a potential clinical relevance by successfully detecting a perfusion defect in the patient scan. It can be concluded that SENCEFUL enables highly resolved ventilation- and perfusion-weighted maps of the human lung to be obtained using proton MRI, and might be interesting for further clinical evaluation. Copyright © 2014 John Wiley & Sons, Ltd.

Purpose To evaluate and to compare Parallel Imaging and Compressed Sensing acquisition and reconstruction frameworks based on simultaneous multislice excitation for high resolution contrast-enhanced myocardial first-pass perfusion imaging with extended anatomic coverage. Materials and Methods The simultaneous multislice imaging technique MS-CAIPIRINHA facilitates imaging with significantly extended anatomic coverage. For additional resolution improvement, equidistant or random undersampling schemes, associated with corresponding reconstruction frameworks, namely Parallel Imaging and Compressed Sensing can be used. By means of simulations and in vivo measurements, the two approaches were compared in terms of reconstruction accuracy. Comprehensive quality metrics were used, identifying statistical and systematic reconstruction errors. Results The quality measures applied allow for an objective comparison of the frameworks. Both approaches provide good reconstruction accuracy. While low to moderate noise enhancement is observed for the Parallel Imaging approach, the Compressed Sensing framework is subject to systematic errors and reconstruction induced spatiotemporal blurring. Conclusion Both techniques allow for perfusion measurements with a resolution of 2.0 × 2.0 mm and coverage of six slices every heartbeat. Being not affected by systematic deviations, the Parallel Imaging approach is considered to be superior for clinical studies.

The aim of this study was to demonstrate that acquisition-weighted 31P magnetic resonance spectroscopy with spatial saturation allows for generation of metabolite maps showing the distribution of 31P metabolites, such as phosphocreatine (PCr) and adenosine triphosphate (ATP) in the human myocardium. The method presented here allowed for a considerable shortening of the normally complicated and time-consuming post-processing. All examinations were performed on a 1.5 T scanner. Contamination from adjacent organs to the myocardial signal was suppressed using spatial saturation pulses and an acquisition-weighted sampling scheme. All measurements were ECG-triggered and performed in prone position. Both healthy subjects and patients with infarcted myocardium were examined. For comparison of the spectroscopic findings to a conventional technique, the infarcted myocardium was additionally examined with a late-enhancement technique. The distribution of PCr of the whole left ventricular myocardium could be determined both in healthy subjects and in patients. The measured distribution of PCr in the infarcted myocardium revealed an obvious reduction of signal in the infarcted area, whereas the distributions of the metabolites in healthy myocardium reflected no discontinuities. The study could demonstrate that the application of spatial saturation pulses facilitates the visual representation of 31P metabolites with a post-processing procedure easy to apply. © 2014 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 187–195, 2013.

Purpose To develop a method to correct for geometric distortions in non-Cartesian echo planar imaging using data acquired in a fast prescan. Methods Echo planar images were obtained using a non-Cartesian density weighted k-space trajectory. In contrast to linear Cartesian acquisition, distortions arising in non-Cartesian acquisitions can only be corrected using conjugate phase-based methods. Up to now these methods require a time consuming field map acquisition in undistorted coordinates. In this work, a phase-labeled reference EPI scan was performed in a very short time, yielding a displacement map in distorted coordinates. Subsequently, this map was applied to itself and thus transformed into undistorted coordinates. The echo planar images were then corrected with a frequency-segmented conjugate phase method. The results were compared with corrections based on a multi-echo reference field map acquired in undistorted coordinates. Results Uncorrected density weighted EPI exhibited geometric distortions and severe ringing artifacts. These distortions could be successfully corrected using the novel method. The quality was comparable to corrections based on the multi-echo reference field map. The novel method shortens the field map acquisition duration by a factor of 64. Conclusion The method presented allows correcting non-Cartesian EPI from a reference scan consisting of only two phase-labeled echo planar images. Magn Reson Med 71:1117–1122, 2014. © 2013 Wiley Periodicals, Inc.

Purpose To optimize the spatial response function (SRF) while maintaining optimal signal to noise ratio (SNR) in T weighted turbo spin echo (TSE) imaging by prospective density weighting. Materials and Methods Density weighting optimizes the SRF by sampling the k-space with variable density without the need of retrospective filtering, which would typically result in nonoptimal SNR. For TSE, the T decay needs to be considered when calculating an optimized sampling pattern. Simulations were carried out and T weighted in vivo TSE measurements were performed on a 3 Tesla MRI system. To evaluate the SNR, reversed centric density weighted and retrospectively filtered Cartesian acquisitions with identical measurement parameters and SRFs were compared with TE = 90 ms and a density weighted k-space sampling optimized to yield a Kaiser function for SRF side lobe suppression for white matter. Results Density weighting of a reversed centric reordering scheme resulted in an SNR increase of (43 ± 13)% compared with the Cartesian acquisition with retrospective filtering while maintaining comparable contrast behavior. Conclusion Density weighting is applicable to TSE imaging and results in significantly increased SNR. The gain can be used to shorten the measurement time, which suggests applying density weighting in both time and SNR constrained MRI.

A reconstruction technique called Model-based Acceleration of Parameter mapping (MAP) is presented allowing for quantification of longitudinal relaxation time and proton density from radial single-shot measurements after saturation recovery magnetization preparation. Using a mono-exponential model in image space, an iterative fitting algorithm is used to reconstruct one well resolved and consistent image for each of the projections acquired during the saturation recovery relaxation process. The functionality of the algorithm is examined in numerical simulations, phantom experiments, and in-vivo studies. MAP reconstructions of single-shot acquisitions feature the same image quality and resolution as fully sampled reference images in phantom and in-vivo studies. The longitudinal relaxation times obtained from the MAP reconstructions are in very good agreement with the reference values in numerical simulations as well as phantom and in-vivo measurements. Compared to available contrast manipulation techniques, no averaging of projections acquired at different time points of the relaxation process is required in MAP imaging. The proposed technique offers new ways of extracting quantitative information from single-shot measurements acquired after magnetization preparation. The reconstruction simultaneously yields images with high spatiotemporal resolution fully consistent with the acquired data as well as maps of the effective longitudinal relaxation parameter and the relative proton density. Magn Reson Med 70:1524-1534, 2013. © 2013 Wiley Periodicals, Inc. Copyright

Background: MRI is the diagnostic mainstay for detection and differ entiation of musculoskeletal tumors. However, a projection regarding the biological dignity of lesions based on standard MRI sequences remains diffi cult and uncertain. This study was undertaken to analyse whether diffusion-weighted MRI (DWI) can distinguish between benign and malignant musculoskeletal tumorous and tumor-like lesions in pediatric patients. Methods: MR examinations of 44 consecutive pediatric patients (26 girls, mean age 1 1±6 years) including standard sequences and DWI (b=50/800 s/mm 2 ) at 1.5 or 3 Tesla were retrospectively evaluated. The study group contained 10 patients with non-treated malignant tumors and 34 patients with benign lesions. Size, relative signal intensity and apparent diffusion coeffi cient (ADC, unit ×10 –3 mm 2 /s) were determined in one lesion per patient. Results: Mean ADC was 0.78±0.45×10 –3 mm 2 / s in patients with malignant tumors and 1.71±0.75 ×10 –3 mm 2 /s in patients with benign lesions (P

Background Fabry cardiomyopathy is characterized by left ventricular (LV) hypertrophy and regional fibrosis. Recent high-end echocardiography studies of selected LV sections suggest an interrelation between regional fibrosis, impaired function, and hypertrophy possibly changing under specific enzyme replacement therapy (ERT). Methods Magnetic resonance imaging (MRI) was used for a region dependent study of cardiac function, morphology and late enhancement (LE) in 25 Fabry patients before and after 12months of ERT in comparison to 43 healthy volunteers. Results Fabry patients presented with LV increased wall thickness (EDWT) and reduced wall thickening (WT) with a focus on basal and midventricular regions corresponding to areas of LE. The degree of hypertrophy and hypokinesia were the highest if LE was detectable. A significant decrease of the EDWT under ERT was observed in LE negative patients accompanied by a decline of hypokinesia with regional differences. Conclusions Regional differences of LV hypertrophy and wall motion were detected corresponding to the distribution of myocardial fibrosis (LE). Functional impairment was closely restricted to fibrotic regions while morphologic changes slightly exceeded the areas of fibrosis. ERT resulted in regional improvements whereby absence of fibrosis was connected to a better outcome.

Purpose: In Fabry disease (FD), a progressive deposition of sphingolipids is reported in different organs. The present study applied 1H magnetic resonance spectroscopy (MRS) to investigate the myocardial lipid content in FD. Materials and Methods: In patients (PTS, n = 15) with genetically proven FD, 1H MRS of the heart was acquired in the same examination as routine cardiac cine and late enhancement MR imaging. Healthy volunteers (n = 11) without history of cardiac disease served as control (CTL). Myocardial triglycerides in vivo were quantified in 1H MRS. Left ventricular (LV) ejection fraction (EF) and late enhancement were assessed for the determination of LV systolic function, and onset or absence of myocardial fibrosis. Results: All 1H MRS revealed resonances for intramyocardial triglycerides. Clinical parameters, e. g. EF (PTS 64 ± 2 % vs. CTL 61 ± 1 %) were similar in PTS and CTL or showed a non-significant trend (LV mass). Apart from a single patient with elevated myocardial triglycerides, no significant impact of Fabry disease on the triglyceride/water resonance ratio (PTS 0.47 ± 0.11 vs. CTL 0.52 ± 0.11 %) was observed in our patient cohort. Conclusion: A comprehensive cardiac evaluation of morphology, function as well as metabolism in Fabry PTS with suspected cardiac involvement is feasible in a single examination. No significant effect of myocardial triglyceride deposition could be observed in patients. The remarkably high myocardial triglyceride content in one patient with advanced FD warrants further studies in PTS with an extended history of the disease.

Diffusion-weighted MRI (DWI) is helpful for detection of brain abscess and pelvic abscess in adults. In the present study, we evaluated the diagnostic performance of DWI in children and young adults with abdominal and soft tissue abscess formations.Seventeen patients (11 females, aged 13 ± 6 years) with suspected abdominal or soft-tissue abscess underwent routine MRI including free-breathing DWI and contrast-enhanced T1w imaging. Seventeen random age-matched patients with non-purulent abdominal fluid collections served as controls. Mean apparent diffusion coefficent (ADC) was measured for abscess, muscle, liver, spleen and kidney tissue as well as for cerebrospinal fluid, urine and free abdominal fluid.All fluid collections were identified on diffusion-weighted images. Thirteen of 14 confirmed abscess formations showed an ADC1.0 × 10(-3) mm(2)/s with a mean value of 0.80 ± 0.38 mm(2)/s. One tuberculous soft-tissue abscess had a higher ADC of 1.85 × 10(-3) mm(2)/s. Ring enhancement on T1w imaging was seen in three non-purulent fluid collections. There were no false-positive findings in the control group.Diffusion-weighted MRI is highly sensitive for abscess and may add specificity to contrast-enhanced T1w imaging of ring-enhancing fluid collections. DWI with free-breathing rapid image acquisition and without the need of intravenous contrast application constitutes a particularly useful choice in pediatric imaging.

This study aimed to compare patients' satisfaction and impact on daily life after implantation of totally implantable venous access ports (TIVAP) in the forearm and the chest.In this prospective study, 50 patients (mean age, 55.8 ± 15.4 years) received three questionnaires on days 1, 30, and 90 after implantation in the forearm (n = 25) or the chest (n = 25). Knowledge concerning device function, comfort perception, and impact of TIVAP on daily activities were evaluated. Ratings were dichotomized depending on whether statements were agreed with or contradicted. Fisher's exact test was used to determine differences between the forearm port (FP) and chest port (CP) groups.There was no significant difference between the two groups with regard to unpleasant feelings (p = 0.09) and discomfort while puncturing (p = 0.06). Main fears in both groups were dysfunction and infection. The possibility of high-pressure injections via the TIVAP was rated important in both groups. More CP patients feared dislocation of their TIVAP during sleep (p0.05). CP patients experienced more negative perceptions while driving a car and wearing brassieres (p0.05) than FP patients. All patients would recommend their device.During certain activities, the FP device seems to be favorable, since it causes less discomfort than the CP.

Purpose: Magnetic resonance imaging systems usually feature linear and shift-invariant (stationary) transform characteristics. The point spread function or equivalently the modulation transfer function may thus be used for an objective quality assessment of imaging modalities. The recently introduced theory of compressed sensing, however, incorporates nonlinear and nonstationary reconstruction algorithms into the magnetic resonance imaging process which prohibits the usage of the classical point spread function and therefore the according evaluation. Methods: In this work, alocal point spread function concept was applied to assess the quality of magnetic resonance images which were reconstructed by an iterative soft thresholding algorithm for compressed sensing. The width of the main lobe of the local point spread function was used to perform studies on the spatial and temporal resolution properties of both numerical phantom and in vivo images. The impact of k-space sampling patterns as well as additional sparsifying transforms on the local spatial image resolution was investigated. In addition, the local temporal resolution of image series, which were reconstructed by exploiting spatiotemporal sparsity, was determined. Finally, the dependency of the local resolution on the thresholding parameter of the algorithm was examined. Results: The sampling patterns as well as the additional sparsifying transform showed a distinct impact on the local image resolution of the phantom image. The reconstructions, which were using x-f-space as a sparse transform domain showed slight temporal blurring for dynamic parts of the imaged object. The local image resolution had a dependence on the thresholding parameter, which allowed for optimizing the reconstruction. Conclusions: Local point spread functions enable the evaluation of the local spatial and temporal resolution of images reconstructed with the nonlinear and nonstationary iterative soft thresholding algorithm. By determining the influence of thresholding parameter and sampling pattern chosen on this model-based reconstruction, the method allows selecting appropriate acquisition parameters and thus improving the results.

To evaluate efficacy, safety, and midterm patency of a helical, self-expanding nitinol stent after failed percutaneous transluminal angioplasty (PTA) of popliteal artery segments P1 and P2 in patients with chronic critical limb ischemia (CLI) or lifestyle-limiting claudication.Between February 2009 and March 2011, 40 patients (23 men; mean age 77±10 years) classified as Rutherford category 3 (n = 10) or 4/5 (n = 30) underwent PTA of the proximal and mid popliteal artery followed by implantation of a SUPERA stent for elastic recoil, residual stenosis, or flow-limiting dissection. All patients had an elevated operative risk. Before and after the procedure and during the 12-month follow-up, a clinical investigation, ankle-brachial-index (ABI) measurement, and color-coded duplex sonography and/or digital subtraction angiography were performed. Primary endpoints were limb salvage and anatomical patency at 12 months.Stent implantation was successful in all patients. The major complication rate was 7.5% (an access-site pseudoaneurysm, 2 retroperitoneal hematomas, and 1 death from retroperitoneal bleeding). Mean follow-up was 15.9 months (range 0.5-27.9). The mean baseline ABI of 0.37 significantly increased to 0.91 at 12 months (p0.01). Three (7.5%) patients underwent bypass surgery owing to lack of clinical improvement (0.10 improvement in ABI). Primary and secondary patency rates at 12 months in the 34 patients eligible for follow-up were 68.4% and 79.8%, respectively. The major amputation rate was 5% at 1 year. Five (12.5%) in-stent stenoses and 1 of 2 (5.0%) in-stent occlusions were successfully recanalized (the second occlusion was asymptomatic).Implantation of this helical stent into segments of the popliteal artery at the knee joint in CLI patients is a safe and clinically effective bailout method with acceptable intermediate patency.

Eine 53-jahrige Patientin stellt sich mit Splenomegalie, unklaren Milzlasionen, Trizytopenie und Verdacht auf Aortitis vor. Sie gibt eine verminderte Leistungsfahigkeit und Muskelschmerzen an. Eine B-Symptomatik ist nicht feststellbar. Die Milzveranderungen sind nach Angabe der Patientin schon langer bekannt. Die Aortitis bestatigt sich laborchemisch und in der MR-Bildgebung. Bezuglich der Milzveranderungen konnen weder sonographisch noch MR-tomographisch konklusive oder gar pathognomonische Befunde erhoben werden. Bei Trizytopenie und diagnostischer Unklarheit wird eine Splenektomie durchgefuhrt und die histologische Diagnose eines multifokalen Littoralzellangioms (LCA) gestellt.

Fast and accurate B1+ mapping is possible using phase-based Bloch–Siegert (BS) methods. Importantly, the off-resonant pulses needed for BS B1+ mapping methods can easily be implemented in multiple MR sequences. BS-based B1+ mapping has thus been introduced for gradient echo (BS-FLASH), spin-echo (BS-SE), and Carr, Purcell, Meiboom, Gill (CPMG)-based multi-SE and turbo-SE sequences. When using SE and multi-SE/turbo-SE-based BS sequences, however, the high intrinsic specific absorption rates must be considered in clinical situations. This study introduces a fast BS B1+ mapping method based on a SE-BURST sequence (BS-SE-BURST). With SE-BURST sequences, multiple low-magnitude excitation pulses are applied prior to the refocusing pulse. Thus, multiple and different phase-encoded echoes can be acquired per excitation cycle. Compared with a SE sequence, this excitation strategy results in a similar signal-to-noise ratio (SNR) per unit time but with reduced specific absorption rate. The proposed BS-SE-BURST sequence was implemented on a conventional 3 T whole body MRI scanner and applied successfully. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.

PurposeTo identify risk factors for the development of catheter-related thrombosis (CRT) in patients with totally implant-able venous access ports (TIVAP) in the forearm, and to analyze the effect of prophylaxis and treatment.MethodsWe retrospectively identified 200 patients (94 men, 106 women, mean age 57.7 +/-14 y) with TIVAP implantation in the forearm between 3/2010 and 11/2010. Type, number of punctures and sonographically defined diameter of the accessed vein were analyzed. Chemotherapy administered prior to the implantation procedure and history of thrombo-embolic events were assessed. Thrombo-embolic prophylaxis (TEP) following port implantation and treatment as well as course of CRT were analyzed.ResultsTwenty-one patients (10.5%) were diagnosed with CRT. Accessed vessels and mean diameter were basilic (n=150, 3.7 mm), brachial (n=39, 3.5 mm) and cephalic (n=11, 3.5 mm) vein. Neither type nor vessel diameter had effect on CRT development (P>.05). Implantation in the left forearm resulted in a significantly higher rate of CRT (P=.04). Ninety-five patients (47.5%) received chemotherapy and 30 patients (15.0%) had a history of thrombosis prior to implantation; both had no effect on development of CRT. Low molecular weight heparin (LMWH) was prescribed in 94/200 patients (47.0%) and had no effect on development of CRT (P>.05). Therapeutic anticoagulation with LMWH resulted in clinical improvement in 12/21 patients (57.4%).ConclusionsTIVAPs of the forearm may be associated with a certain rate of early and late CRT. The simplest vein to puncture should be selected for vascular access. Thrombo-embolic prophylaxis appears to be rather ineffective for prevention of CRT.

To analyze the remodeling processes of the infarct territory in the time course of infarct healing.Serial late enhancement (LE) studies were performed in 30 patients following reperfused myocardial infarction (MI) in the first and second week post-MI and after 3 months. To characterize infarct remodeling over time, the following variables were derived and analyzed in a blinded fashion: Infarct size (IS, in mm(3)), maximum infarct thickness (IT(max), mm), mean infarct thickness (IT(mean), mm) and the variability of infarct thickness (VIT=IT(max)/IT(mean)). Further, a new parameter for the assessment of infarct remodeling, the infarct extent (IE, mm(2)) was computed. IE quantifies IS in two dimensions along the heart's circumferential and longitudinal directions. IS was divided by the IE to obtain IT(mean).Overall infarct thickness was highly variable. Infarct shrinkage due to infarct thinning and IE reduction was found in the first months of healing. IS, IT(mean) and IT(max) significantly decreased during follow-up. There was a less consistent change of the IE: IE decreased in 75% of all infarcts from the first week up to 3 months post-MI, whereas 25% of infarcts expanded. Infarct thinning was found in almost all patients (92%), hence occurring in patients with infarct expansion and in patients without infarct expansion.Infarct thinning and-to a lesser extent-IE reduction, contribute to infarct shrinkage in the time course of infarct healing. Infarct thinning may occur without infarct expansion.

The response of myocardial blood flow to sympathetic stimulation with cold is modulated by endothelium-related factors. As endothelial dysfunction is an early step in patients with coronary artery disease, the aim of this study was to establish a cold pressor test (CPT) setting for quantitative analysis of myocardial perfusion in a MR scanner. First pass perfusion studies were performed in 10 healthy volunteers using a 1.5 T MR scanner with a multislice steady state free precession perfusion trueFISP sequence in prebolus technique (1 cc/4 cc gadobenate dimeglumine). MR-CPT was established using an over head ice-water bath of the left hand. First pass perfusion imaging was started after 1 min to assure an adequate stimulus followed by a second series after 15 min to evaluate the rest perfusion. After motion correction images were segmented with an adapted, automated tool, myocardial contours were determined. Perfusion was quantitatively evaluated after contamination and baseline correction by deconvolution with the arterial input function using an exponential function model as residuum. All data could be evaluated. Mean myocardial perfusion rose from 0.61 ± 0.22 cc/g/min at rest to 1.15 ± 0.34 cc/g/min under CPT. MR myocardial perfusion values show a comparable increase under CPT as published positron emission tomography data. Consequently, CPT for the presence of endothelial dysfunction is feasible in the MR environment. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.

Background Conventional totally implantable venous access ports (TIVAPs) are not approved for power contrast injections but often remain the only venous access site in oncologic patients. Therefore, these devices can play an important role if patients with a TIVAP are scheduled for a contrast-enhanced computed tomography (ceCT) as vascular access may become more difficult during the course of chemotherapy. Purpose To evaluate the feasibility and safety of power injections in conventional TIVAPs in the forearm and to analyze the feasibility of bolus triggering during CT scans. Material and Methods In this retrospective study we analyzed 177 power injections in 141 patients with TIVAPs in the forearm. Between October 2008 and March 2010 all patients underwent power injections (1.5 mL/s, 150 psi) via the TIVAP for ceCT because conventional vascular access via a peripheral vein had failed. Adequate functioning and catheter's tip location after injection were evaluated. Peak injection pressure and attenuation levels of aorta, liver and spleen were analyzed and compared with results of 50 patients who were injected via classical peripheral cannulas (3 mL/s, 300 psi). Feasibility of automatic scan initiation was evaluated. In vitro the port was stressed with 5 mL/s (300 psi). Results One TIVAP showed tip dislocation with catheter rupture. Three (2.1%) devices were explanted owing to assumed infection within 4 weeks after the injection. Mean injection pressure was 121.9 +/−24.1 psi. Triggering with automatic scan initiation succeeded in 13/44 (29.6%) scans. Injection via classical cannulas resulted in significantly higher enhancement (p < 0.05). In vitro the port system tolerated flow rates of up to 5 mL/s, injection pressures of up to 338 psi. Conclusion Power injection is a safe alternative for patients with TIVAPs in the forearm if classic vascular access ultimately fails. Triggering was successful in one-third of the attempts. Image quality in the arterial phase scan may be hampered. In vitro results suggest that the device tolerates even higher flow rates.

The authors report the case of a patient with acute lower limb ischemia (category IIa) after occlusion of the popliteal artery due to fracture of a long indwelling stent. The patient refused surgical therapy for religious reasons, and an interventional revascularization was performed as acute rescue therapy. After reentry into the distal popliteal artery was achieved, the artery was dilated, and the fragmented stent was crushed, followed by implantation of two helical nitinol stents with high radial force and a third self-expandable nitinol stent. Sufficient primary technical success was achieved, and stent patency was present at midterm follow-up.

PurposeTo evaluate indications for, and complications during, explantation of interventionally placed totally implantable venous access ports (TIVAPs) of the forearm.BackgroundMany studies analyze the explantation procedure of pectorally placed TIVAPs. The literature on TIVAPs in the forearm is limited, and the explantation procedure of these devices in the forearm has not been sufficiently evaluated yet.MethodsWe retrospectively reviewed the archives of our institute between May 2006 and May 2009 and identified 850 TIVAPs that had been implanted in the forearm. Of these TIVAPs, 145/850 (80 in women, 65 in men; mean age 52 years, range 15–82 years) were explanted during this period either by interventionists (n=109) or by general surgeons (n=36).ResultsMean catheter survival was 322 days. Reasons for explantation were end of therapy (63.4%), infection (29.0%), thrombosis (3.4%), occlusion (1.4%), or dislocation (1.4%) of the TIVAP. Primary technical success rate was 97.2% for the surgical as well as for the interventional procedure. The overall success rate was 100%. The reasons for retrieval failure by interventionists (3/108) as well as by surgeons (1/36) were post-thrombotic adhesions of the port catheter to the blood vessel wall.ConclusionsRemoval of TIVAPs of the forearm shows a high technical success rate and a low complication rate. End of therapy is the most common indication for explantation. There is a low risk of interventional removal failure with a resulting need for open surgery to remove the device.

Aortic valve disease shows a rising incidence with the increasing mean age of Western populations. The detection of hemodynamic parameters, which transcends the mere assessment of valve morphology, has an important future potential concerning classification of the severity of disease. MRI allows a non-invasive and a spatially flexible view of the aortic valve and the adjacent anatomic region, left ventricular outflow tract (LVOT) and ascending aorta. Moreover, the technique allows the determination of functional hemodynamic parameters, such as flow velocities and effective orifice areas. The new approach of a serial systolic planimetry velocity-encoded MRI sequence (VENC-MRI) facilitates the sizing of blood-filled cardiac structures with the registration of changes in magnitude during systole. Additionally, the subvalvular VENC-MRI measurements improve the clinically important exact determination of the LVOT area with respect to its specific eccentric configuration and its systolic deformity.

With the increasing life expectancy of our patients, the prevalence of peripheral artery disease grows, and so does the need for therapy of this disease [1]. Various therapy regimens like conservative therapy (e.g., exercise), minimally invasive procedures (e.g., percutaneous transluminal angioplasty [PTA], stent) and surgery (e.g., bypass) exist. Because of their less invasive character, and depending on the vascular lesion, interventional procedures are the firstline therapy for peripheral artery disease in many centers [2, 3]. Stenting of the femoral artery is mainly performed if the initial result of PTA is not satisfactory, or to control complications after PTA [2–4]. We report the unique complication of acute and complete stent collapse immediately after stent implantation in a highly rigid stenosis after conventional and cutting balloon angioplasty had ultimately failed.

Heutige Verfahren zur Lungenfunktionsuntersuchung erlauben nur globale Analysen oder sind auf die Anwendung radioaktiver Tracer angewiesen. Wunschenswert waren jedoch quantitative, regional aufgeloste Techniken ohne jegliche Strahlenexposition. Der vorliegende Artikel stellt die sauerstoffverstarkte MR-Lungenfunktionsventilationsmessung vor. Erstmalig 1996 am Menschen eingesetzt, liegen bereits zahlreiche Erfahrungen mit 1,5-Tesla-Systemen vor. Dabei erwies sich insbesondere die quantitative T1-Bildgebung als zukunftsfahiges Verfahren. Besonders attraktiv fur die funktionelle Lungenbildgebung sind so genannte offene Niederfeld-MR-Systeme. Vorteile sind die Patientenfreundlichkeit des Systems, insbesondere fur die Untersuchung von Kindern und Jugendlichen, niedrige Kosten durch Verzicht auf Heliumkuhlung und die deutlich geringere Gerauschentwicklung. Geringere Signal-zu-Rausch-Verhaltnisse konnen durch veranderte Relaxationszeiten ausgeglichen werden. Neuere Navigationstechniken ermoglichen weitere Kompensationen. Der vorliegende Artikel fokussiert auf die Darstellung der Niederfeld-Lungen-MRT und stellt T1- wie auch T2*-Messungen an Probanden und ersten Patienten vor.

Purpose To determine sensitivity, specificity and inter-observer variability of different whole-body MRI (WB-MRI) sequences in patients with multiple myeloma (MM). Methods and materials WB-MRI using a 1.5 T MRI scanner was performed in 23 consecutive patients (13 males, 10 females; mean age 63 ± 12 years) with histologically proven MM. All patients were clinically classified according to infiltration (low-grade, n = 7; intermediate-grade, n = 7; high-grade, n = 9) and to the staging system of Durie and Salmon PLUS (stage I, n = 12; stage II, n = 4; stage III, n = 7). The control group consisted of 36 individuals without malignancy (25 males, 11 females; mean age 57 ± 13 years). Two observers independently evaluated the following WB-MRI sequences: T1w-TSE (T1), T2w-TIRM (T2), and the combination of both sequences, including a contrast-enhanced T1w-TSE with fat-saturation (T1 ± CE/T2). They had to determine growth patterns (focal and/or diffuse) and the MRI sequence that provided the highest confidence level in depicting the MM lesions. Results were calculated on a per-patient basis. Results Visual detection of MM was as follows: T1, 65% (sensitivity)/85% (specificity); T2, 76%/81%; T1 ± CE/T2, 67%/88%. Inter-observer variability was as follows: T1, 0.3; T2, 0.55; T1 ± CE/T2, 0.55. Sensitivity improved depending on infiltration grade (T1: 1 = 60%; 2 = 36%; 3 = 83%; T2: 1 = 70%; 2 = 71%; 3 = 89%; T1 ± CE/T2: 1 = 50%; 2 = 50%; 3 = 89%) and clinical stage (T1: 1 = 58%; 2 = 63%; 3 = 79%; T2: 1 = 58%; 2 = 88%; 3 = 100%; T1 ± CE/T2: 1 = 50%; 2 = 63%; 3 = 100%). T2w-TIRM sequences achieved the best reliability in depicting the MM lesions (65% in the mean of both readers). Conclusions T2w-TIRM sequences achieved the highest level of sensitivity and best reliability, and thus might be valuable for initial assessment of MM. For an exact staging and grading the examination protocol should encompass unenhanced and enhanced T1w-MRI sequences, in addition to T2w-TIRM.

Respiratory motion and pulsatile blood flow can generate artifacts in morphological and functional lung imaging. Total acquisition time, and thus the achievable signal to noise ratio, is limited when performing breath-hold and/or electrocardiogram-triggered imaging. To overcome these limitations, imaging during free respiration can be performed using respiratory gating/triggering devices or navigator echoes. However, these techniques provide only poor gating resolution and can induce saturation bands and signal fluctuations into the lung volume. In this work, acquisition schemes for nonphase encoded navigator echoes were implemented into different sequences for morphological and functional lung imaging at 1.5 Tesla (T) and 0.2T. The navigator echoes allow monitoring of respiratory motion and provide an ECG-trigger signal for correction of the heart cycle without influencing the imaged slices. Artifact free images acquired during free respiration using a 3D GE, 2D multislice TSE or multi-Gradient Echo sequence for oxygen-enhanced T2* quantification are presented.

PURPOSE: 31 P MR spectroscopy (MRS) allows the noninvasive assessment of metabolic alterations in tumors. Due to physical as well as technical limitations, mostly large and single voxels are used. We used a spatially resolved 31 P MRS technique to characterize metabolic abnormalities inside and adjacent to liver metastases of patients with uvea melanoma. MATERIALS AND METHODS: Optimization of 3D chemical shift imaging (3D CSI) was performed in healthy volunteers (n = 19; voxel size 25 ml). Patients (n = 8) with liver metastases were then examined. Cross sectional imaging was available for all patients. RESULTS: Compared to healthy volunteers, the PME/PDE ratios of patients with liver metastasis were significantly higher (0.56 ± 0.30 vs. 0.39 ± 0.21; p < 0.05). A trend towards increased PME/beta ATP ratios (2.07 ± 1.83 vs. 1.02 ± 0.45; p = 0.12) and decreased Pi/PME ratios (0.57 ± 0.29 vs. 1.06 ± 0.58; p = 0.06) was also observed. Patients with metastases ≥ 5 cm showed significantly higher PME/PDE ratios (0.68 ± 0.17 vs. 0.45 ± 0.03; p < 0.05). Liver parenchyma adjacent to metastases did not show any significant changes compared to non-diseased tissue. CONCLUSION: 3D CSI allows the simultaneous analysis of metabolic alterations in diseased as well as in healthy human liver. Metastases show significant metabolic alterations. Thus, 31 P MRS opens new possibilities for therapeutic monitoring.

The purpose of this study was to evaluate a computer-aided diagnosis (CAD) tool compared to human observers in quantification of interstitial lung disease (ILD) in patients with collagen-vascular disorders. A total of 52 patients with rheumatoid arthritis (n = 24), scleroderma (n = 14) and systemic lupus erythematosus (n = 14) underwent thin-section CT. Two independent observers assessed the extent of ILD (EoILD), reticulation (EoRet) and ground-glass opacity (EoGGO). CAD assessed EoILD twice. Pulmonary function tests were obtained. Statistical evaluation used 95% limits of agreement and linear regression analysis. CAD correlated well with diffusing capacity (DLCO) (R = −0.531, P

OBJECTIVES: The present study investigated changes in cardiac energy metabolism and function in patients with dilated cardiomyopathy (DCM) before and after exercise training (ET) with phosphorus-31 magnetic resonance spectroscopy (MRS) in combination with magnetic resonance imaging (MRI). BACKGROUND: Exercise training might have a beneficial role on myocardial function and oxidative metabolism in DCM, but it is unclear whether the additional load on the failing heart leads to deterioration of cardiac energy metabolism. METHODS: Twenty-four patients were randomized to an exercise (age 53 +/- 12 years) or a control (age 56 +/- 6 years) group. Supervised ET was performed for 2 months, followed by 6 months of self-regulated training. At baseline and 2 and 8 months, maximal exercise testing along with quantitative MRS and MRI studies were performed. RESULTS: The effectiveness of ET was demonstrated by a 17% increase in peak oxygen uptake (p < 0.05). Exercise training improved left ventricular (LV) end-systolic volume (p < 0.05) and LV ejection fraction (30 +/- 15% vs. 37 +/- 15%; p < 0.01) but not right ventricular parameters. The improvement in cardiac function was not accompanied by changes in cardiac high-energy phosphate concentrations; phosphocreatine, adenosine triphosphate, and the phosphocreatine/adenosine triphosphate ratio were all unchanged after training. CONCLUSIONS: The observation that LV function improved and LV energy metabolism remained unchanged suggests that the beneficial effect of ET on LV function is achieved without adversely affecting metabolism. These findings lend further support for the use of ET as an adjunct therapy in DCM.

Purpose MR stress perfusion imaging of the heart allows the quantification of myocardial perfusion and the evaluation of myocardial perfusion reserve (MPR) and the ratio of subendocardial to subepicardial perfusion at rest and under adenosine stress. The aim of this study was to evaluate a high-resolution GRAPPA sequence for quantitative MR first pass perfusion imaging in healthy volunteers. Materials and methods First pass stress and rest perfusion studies were performed on 10 healthy volunteers using a 1.5 T MR scanner with a multislice SR-TrueFISP first pass perfusion sequence with a GRAPPA algorithm (acceleration factor 3) in prebolus technique and an image resolution of 1.8 x 1.8 mm. For the comparison group, we examined 12 different healthy volunteers with a standard first pass perfusion SR-TrueFISP sequence using a resolution of 2.7 x 3.3 mm. Myocardial contours were manually delineated followed by an automatic division of the myocardium into two rings with an equal thickness for the subendo- and subepicardial layer. Eight sectors per slice were evaluated using contamination and baseline correction. Results Using the GRAPPA sequence, the ratio of subendo- to subepimyocardial perfusion was 1.18 +/- 0.32 for the examination at rest. Under pharmacologically induced stress, the ratio was 1.08 +/- 0.27. For the standard sequence the ratio was 1.15 +/- 0.28 at rest and 1.11 +/- 0.33 under stress. For the high resolution sequence higher mean values for the subendo- to subepimyocardial ratio were obtained with comparable standard deviations. The difference between the sequences was not significant. Conclusion The evaluation of subendomyocardial and subepimyocardial perfusion is feasible with a high-resolution first pass perfusion sequence. The use of a higher resolution to avoid systematic error leads to increased image noise. However, no relevant reduction in the quantitative perfusion values under stress and at rest was able to be depicted.

Background: Cardiac computed tomography (CT) has become an established complement in cardiac imaging. Thus, optimized image quality is diagnostically crucial. Purpose: To prospectively evaluate whether, by using 64-slice CT, a specific reconstruction interval can be identified providing best image quality for all coronary artery segments and each individual coronary artery. Material and Methods: 311 coronary segments of 14 men and seven women were analyzed using 64-slice CT. Data reconstruction was performed in 5% increments from 5–100% of the R–R interval. Four experienced observers independently evaluated image quality of the coronary arteries according to the AHA classification. A three-point ranking scale was applied: 1, very poor, no evaluation possible; 2, diagnostically sufficient quality; 3, highest image quality, no artifacts. Results: The best reconstruction point for all segments was found to be 65% of the R–R interval (mean value 2.4±0.5; P Conclusion: By using 64-slice CT, the need for adjusting the reconstruction point to each coronary segment might be overcome. Best image quality was achieved with image reconstruction at 65% of the R–R interval for all coronary segments as well as each coronary artery.

OBJECTIVE. Exclusion of coronary artery calcifications has a high negative predictive value for the diagnosis of coronary artery disease. However, it is known that significant differences in calcium scoring can occur because of the ECG trigger interval. Thus, the aim of the study was to evaluate the influence of different reconstruction intervals on detection of any coronary calcium by using MDCT and retrospective cardiac gating.CONCLUSION. For a true exclusion of coronary artery calcifications, different reconstruction intervals have to be evaluated.

The aims of this study were (1) to assess the diagnostic performance of multidetector row computed tomography angiography (CTA) on imaging of renal artery branches and (2) to investigate the effect of different iodine concentrations at constant total iodine load and either constant injection rates or constant iodine administration rates. A number of 120 consecutive patients (71+/-6 years of age) underwent CTA of renal arteries (collimation 4 x 1 mm) using the nonionic contrast medium iopromide, and were divided into six equal groups: 1: 150 ml, 240 mg/ml at 4 ml/s; 2: 120 ml, 300 mg/ml at 4 ml/s; 3: 97.3 ml, 370 mg/ml at 4 ml/s; 4: 150 ml, 240 mg/ml at 5 ml/s; 5: 120 ml, 300 mg/ml, 60 ml at 6 ml/s, 60 ml at 3 ml/s; 6: 97.3 ml, 370 mg/ml at 3.3 ml/s. The image quality of the main renal arteries (n=240) and their first-order to fourth-order branches was scored as 0 for no visualization, 1 for only visualization, and 2 for diagnostic. All main renal arteries were diagnostic. First-order branches had score 2 in 38/40, 40/40, 37/40, 38/40, 39/40, and 40/40 patients for groups 1-6, respectively (p=0.34). Second-order branches were imaged best in group 2 (p

Purpose To determine whether the recently applied technique of acquisition-weighted 31P-MR spectroscopy (AW-MRS) allows for the detection of depressed energy metabolism in patients with inferior wall myocardial infarctions. Materials and Methods Eight patients with subacute myocardial infarction and wall motion abnormalities restricted to the inferior wall were examined with a 1.5-T MR scanner. Global and regional left ventricular (LV) function was assessed by cine MRI, and the size and extent of myocardial infarction was assessed by late enhancement (LE). MRS was performed with an AW three-dimensional chemical shift imaging sequence. Phosphocreatine/ATP ratios were determined with the postprocessing model AMARES for four voxels positioned in the anterior, lateral, inferior, and septal parts of the LV. Results The LV ejection fraction (EF) was reduced to 37.5% ± 9.0%. Seven of eight patients had transmural LE in the inferior wall, and one patient showed subendocardial enhancement in the inferior-lateral parts. Phosphocreatine/ATP ratios of the inferior wall were significantly reduced (P < 0.05) compared to all other parts of the LV (1.03 ± 0.39 (inferior), 1.67 ± 0.81 (lateral), 1.73 ± 0.29 (anterior), and 1.49 ± 0.31 (septal)). The ratios in five of seven patients with transmural enhancement were

In myotonic dystrophy type 2 (DM2/PROMM), cardiac muscle involvement is usually more benign than in DM1, but clinically severe cardiomyopathy has been reported in some patients. Using a novel method of magnetic resonance spectroscopy (MRS), we examined the left ventricular myocardium and the left gastrocnemius muscle in 11 unselected DM2/PROMM patients without overt cardiac disease. Data on cardiac morphology and function were obtained by gradient echo two-dimensional cine magnetic resonance imaging (MRI); no significant differences were found between DM2 patients and healthy controls, but using a median split approach older patients showed mildly increased left ventricular (LV) volumes, i.e., 59% increase of end-systolic volume index (ESVI) and 35% increase of end-diastolic volume index (EDVI), and an increase of LV mass (26%). On cardiac MRS, DM2/PROMM patients showed a reduction of phosphocreatine (PCr) and adenosine triphosphate (ATP) by 25 and 20% compared to matched healthy controls. No significant differences were found between younger and older patients. In skeletal muscle of the DM2 patients, no significant decrease of PCr and ATP concentrations was found. However, in older patients, who commonly show overt hip flexor muscle weakness, we observed reduced values for PCr and ATP. Our MRS and MRI findings reveal evidence for subclinical cardiomyopathy in DM2/PROMM patients without overt heart disease. Future prospective studies are needed to clarify the risk of developing overt cardiac disease in DM2 and to define prognostic factors.

The purpose of this study was to present the prebolus technique for quantitative multislice myocardial perfusion imaging. In quantitative MR perfusion studies the maximum contrast agent dose is limited by the requirement to determine the arterial input function (AIF). The prebolus technique consists of two consecutive contrast agent administrations. The AIF is determined from a first low-dose bolus, while a second, high-dose bolus allows the measurement of the myocardium with improved signal increase. The results of the prebolus technique using a multislice saturation recovery trueFISP sequence in healthy volunteers are presented. In comparison to a standard dose of 3 ml Gd-DTPA, perfusion values are maintained while the signal increase in the concentration time courses was considerably improved, accompanied by reduced standard deviations of the obtained perfusion values (0.72 ± 0.13 ml/g/min for 1 ml/8 ml and 0.67 ± 0.10 ml/g/min for 1 ml/12 ml Gd-DTPA, respectively). Magn Reson Med 52:296–299, 2004. © 2004 Wiley-Liss, Inc.

Liver tumors are defined using quantitative dynamic contrast-enhanced ultrasound compared to histological diagnosis, respectively, long-term follow-ups. Forty-two focal liver lesions in 39 patients were examined by contrast harmonic imaging over a period of 2 min after bolus injection of 10-ml galactose-based contrast agent. Vascular enhancement was quantified by using a dedicated software that allowed us to place representative regions of interest (ROI) in the center of the lesion, in the complete lesion, in regular liver parenchyma and in representative liver vessels (artery, vein and portal vein). Peak enhancement was judged to be either in the arterial, portal venous or in the late phase of liver perfusion. The lesion was described as hypovascular, isovascular and hypervascular compared to liver parenchyma. Contrast uptake was described as centrifugal or centripetal and peripheral or homogenous, respectively. Characterization of the lesions was performed unenhanced and after contrast by four independent specialists unaware of histology. Diagnosis of malignancy was evaluated by using a receiver operating characteristic (ROC) analysis, also overall accuracy, average sensitivity, specificity and negative and positive predictive values were calculated. Interobserver agreement was defined by the Kappa statistics. Histologic examination revealed 29 malignant [hepatocellular carcinoma (HCC), n=11; cholangiocellular carcinoma (CCC), n=1; lymphoma, n=1; metastases, n=16)] and 7 benign [hemangioma, n=1; focal nodular hyperplasia (FNH), n=4, adenoma, n=2)] lesions. Six benign lesions (hemangioma n=1; FNH n=5) were proved by long-term follow-up. ROC analysis regarding the diagnosis of malignancy showed values from 0.43 to 0.62 (mean 0.57) before and from 0.70 to 0.80 (mean 0.75) after contrast agent, respectively. The average values for sensitivity, specificity, accuracy and negative and positive predictive values were 66, 26, 62, 45 and 73% unenhanced and 83, 49, 73, 65 and 82% after contrast, respectively. The interobserver agreement was 0.54 and 0.65 for unenhanced and enhanced examinations, respectively. Quantitative dynamic contrast-enhanced sonography improves the diagnosis of malignancy in liver lesions.

Myocardial MR first-pass perfusion time courses are contaminated by signals from the ventricles (spillover) as a consequence of partial volume effects and motion. An early increase in the signal intensity from the myocardium is an indicator of contamination. This contamination leads to under- or overestimation of perfusion, depending on the amount of contamination. In this work a simple method for contamination correction is proposed: curves proportional to the signal intensity time courses in the ventricles are subtracted from the signal intensity time courses in the myocardium to minimize the variance of signal before the arrival of the contrast medium in the myocardium. The proposed correction is easy to apply, removes the contamination, and leads to more precise perfusion values.

Computed tomography reliably evaluates hypopharyngeal squamous cell carcinomas (SCC) regarding the infiltration of specific anatomic structures and tumor volumes, both of which have been shown to be predictors of local control in patients treated with radiation therapy alone. However, an association of specific infiltrated structures and/or tumor volume with local control has not been investigated for surgical treatment; thus, we determined relationships of various infiltrated anatomic structures and tumor volume with local control in patients with hypopharyngeal SCC treated with primary surgery. In 45 hypopharyngeal SCC, tumor volumes were measured by pretreatment CT, and extent of tumor infiltration was determined by postoperative pathologic examination. All patients had clinical follow-up for recurrent tumor at the primary site. Statistical analysis basically consisted of chi-square and U-tests. Local control rate was 84.4% (38 of 45). Tumor volume was significantly associated with local control (p=0.004). Six of 16 (38%) patients with tumor volumesor =8.1 cm3 (mean) had a local recurrence, which is significantly (p=0.003) more compared with 1 of 29 (3%) in the group of patients with volumes8.1 cm3. Among all evaluated anatomic structures, only a tendency for significant association with local control was found for tumor involvement of the tonsils and the extralaryngeal soft tissues. The determination of tumor volumes by CT helps predict local control in patients with hypopharyngeal SCC treated with primary surgery.

Ziel dieser Studie war es, verschiedene Parameter der linksventrikularen Wandbewegung aus MR-tagging-Aufnahmen quantitativ zu analysieren. Die Auswertemethode sollte angewendet werden, um den physiologischen Kontraktionsablauf zu charakterisieren und pathophysiologische Veranderungen zu erfassen. Die Tagginguntersuchung wurde in einer basisnahen, mittventrikularen und einer apikalen Schicht des linken Ventrikels durchgefuhrt. Fur die automatische Quantifizierung von Rotation, Kontraktion und Umfangverkurzung wurde eine geeignete Software erstellt. Die Methode wurde bei 8 gesunden Probanden, 13 Patienten mit Aortenstenose vor und ein Jahr nach Klappenersatz und 10 Patienten mit Myokardinfarkt vor und nach Revaskularisation angewendet. Die von uns entwickelte Software gestattet die Quantifizierung der linksventrikularen Wandfunktion uber die Bestimmung von Rotation, Kontraktion und Umfangsverkurzung. Bei den Probanden zeigte sich eine Wringbewegung mit gegenlaufiger Rotation der Herzbasis zur Herzspitze. Vor Klappenersatz zeigten die Patienten mit Aortenstenose eine signifikant verstarkte apikale Rotation und Torsion. Ein Jahr postoperativ hatte sich die Torsion normalisiert. Bei den Patienten mit Myokardinfarkt zeigte sich nach Revaskularisierung eine Zunahme der Umfangverkurzung im Infarktareal. Die Quantifizierung der linksventrikularen Wandbewegung mit MR-tagging-Aufnahmen ermoglicht die Charakterisierung und Verlaufsbeobachtungen von Veranderungen der linksventrikularen Wandfunktion bei verschiedenen Herzerkrankungen.

Experimental studies demonstrated persistently increased 23Na content in nonviable myocardium post-myocardial infarction (MI). We hypothesized that nonviable myocardium in humans would show elevated 23Na content at all stages of infarct development, and therefore could be imaged with 23Na MRI. Ten patients were examined on days 4, 14, and 90 after infarction, and five of these patients participated in a 12-month follow-up. Double angulated short-axis cardiac 23Na images were obtained with the use of a 23Na surface coil and an ECG-triggered, 3D gradient-echo sequence. 1H T2-weighted imaging (N = 9) was performed on days 4, 14, and 90. Wall motion was assessed by cine MRI, and the infarct size was determined by late enhancement on day 90. The 23Na signal intensity (SI) of infarcted myocardium was expressed as the percentage increase over 23Na SI of noninfarcted myocardium. All of the patients showed an area of elevated SI on 23Na and 1H T2-weighted images that correlated with wall motion abnormalities and late enhancement. 23Na SI was highest on day 4. It then decreased until day 90, but remained elevated (39% ± 18%, 31% ± 17%, 28% ± 13% on days 4, 14, and 90, respectively, P = 0.001). No further decrease was found 1 year after infarction (25% ± 7%, P = 0.89 vs. day 90). 1H T2-weighted SI decreased between days 4 and 14, but on day 90 only six of nine patients had a residual elevated SI. Thus, 23Na SI is elevated in nonviable infarction at all time points following MI, and 23Na MRI may become a suitable technique for imaging nonviable myocardium in humans. Magn Reson Med 52:545–551, 2004. © 2004 Wiley-Liss, Inc.

Indirect qualitative MRI of pulmonary function is feasible using the paramagnetic effects of oxygen physically dissolved in blood. In this study, a more quantitative oxygen-enhanced pulmonary function test based on the slope of a plot of R1 vs. oxygen concentration—the oxygen transfer function (OTF)—was developed and tested in a pool of five healthy volunteers and five patients with cystic fibrosis (CF). The lung T1 relaxation rate, R1, under normoxic conditions (room air, 21% O2), and the response to various hyperoxic conditions (40%–100% O2) were studied. Lung T1 in healthy volunteers showed a relatively homogeneous distribution while they breathed room air, and a homogeneous decrease under hyperoxic conditions. Lung T1 in CF patients showed an inhomogeneous distribution while they breathed room air, and the observed lung T1 decrease under hyperoxia depended on the actual state of the diseased lung tissue. In the selected group of CF patients, areas with reduced OTF also showed reduced perfusion, as confirmed by qualitative contrast-enhanced MR pulmonary perfusion imaging. The results demonstrate that this completely noninvasive oxygen-enhanced pulmonary function test has potential for clinical applications in the serial diagnosis of lung diseases such as CF. Magn Reson Med 51:1009–1016, 2004. © 2004 Wiley-Liss, Inc.

Purpose To show the application of auto-sensitivity encoding (SENSE)—a self-calibrating parallel imaging technique—to first pass perfusion imaging of the whole human heart. Materials and Methods The self-calibrating parallel imaging method auto-SENSE was implemented for a saturation recovery turbo-fast low-angle shot (FLASH) sequence on a 1.5-T scanner using a standard four-element body phased array coil. By reducing the acquisition time per slice by a factor of two compared to conventional turbo FLASH imaging, the number of imaged slices could be doubled to six to ten with an unchanged temporal resolution of one image per heartbeat. This technique has been tested in eight healthy volunteers for contrast-enhanced heart perfusion imaging. Results Auto-SENSE heart perfusion imaging with improved coverage of the human heart could be performed successfully in all volunteers. A first quantitative comparison of perfusion values between the auto-SENSE and the non-SENSE techniques shows good agreement. Conclusion Auto-SENSE allows perfusion imaging of the whole human heart without gaps. J. Magn. Reson. Imaging 2003;18:702–708. © 2003 Wiley-Liss, Inc.

Malignant hyperthermia (MH) is a metabolic myopathy with an abnormal release of calcium by the sarcoplasmic reticulum (SR), triggered by volatile anesthetics and succinylcholine. Similarly, caffeine enhances Ca(2+)release by the SR in vitro. In a prospective, randomized study, high-energy phosphates were studied by intramuscular 31-phosphorus magnetic resonance spectroscopy ((31)P-MRS) in 10 MH-susceptible (MHS) and 7 MH-nonsusceptible (MHN) subjects before and after injection of 0.5 ml caffeine (20 mM). Intramuscular energy balance, measured by the ratios of P(i)/PCr and P(i)/gamma-ATP, did not differ between MHS and MHN patients before and after intramuscular caffeine injection. However, within each group, P(i)/PCr and P(i)/gamma-ATP increased significantly only in the MHS group. Intramuscular caffeine injection seemed to impair the metabolic balance in MHS individuals. This may reflect a local calcium overload leading to consumption of high-energy phosphates and increase of inorganic phosphate. Intramuscular stimulation by caffeine and (31)P-MRS may provide a valuable tool to investigate MH-related metabolic disturbances.

Purpose: To evaluate the feasibility and reproducibility of a noninvasive, rapid and quantitative pulmonary perfusion mapping method using a two-compartment tissue model in combination with a 1H spin labeling technique. Materials and Methods: Ten healthy volunteers and three patients with cystic fibrosis (CF) were examined on a 1.5-T whole-body scanner. Global and selective lung T1 maps based on an inversion recovery Snapshot FLASH technique were acquired from each subject with breath-holds at end-expiration. For comparison, corresponding Gd-DTPA-enhanced 1H MR perfusion images were also obtained from each CF patient. Results: Quantitative perfusion maps were calculated from the global and selective T1 maps. The measured perfusion rates of the upper right lung in volunteers ranged from 400 to 600 mL/100 g/minute. The method showed a high intra-study reproducibility and low relative errors. In CF-patients, perfusion defects detected using Gd-DTPA-enhanced MR imaging were also detected using the spin labeling method. The perfusion rates of diseased lung tissues were less than 200 mL/100 g/minute. Conclusion: Noninvasive, robust and quantitative 1H MR mapping of pulmonary perfusion was successfully performed using a rapid lung T1 mapping in combination with spin labeling within the imaging slice. The proposed method has the potential to provide both important qualitative functional information and quantitative pulmonary perfusion rates in various lung diseases at various stages without the need of contrast agents. J. Magn. Reson. Imaging 2003;18:260–265. © 2003 Wiley-Liss, Inc.

Peripheral arterial occlusive disease (PAOD) of the lower limb is a widely spread disease at the present time. After clinical examination, which includes a comprehensive history of the patient, different imaging modalities are competitive in the exact assessment of PAOD. Besides digital subtraction angiography and MR -angiography, color Doppler US is an established imaging modality in the diagnosis of PAOD. This article illustrates the typical color Doppler US findings in PAOD of the lower limb. Duplex images of normal and pathological findings are presented, and the limitations of the method are pointed out. Color Doppler US examination strategies in patients suffering of PAOD are outlined.

The histological detection of a peritumoral lymphocytic infiltration (PLI) and a sharp tumor border in patients with squamous cell carcinoma (SCC) of the larynx, pharynx or oral cavity is inversely correlated with the development of cervical lymph node metastases and is therefore a favorable prognostic factor. However, preoperative biopsies are often too small for an evaluation of these tumor features. Here, we examined retrospectively whether elevation of peritumoral density values as determined by contrast-enhanced computed tomography (CT) correlates with PLI and the presence of cervical lymph node metastases. A total of 40 patients with primarily resected SCC were studied (pT1=8, pT2=13, pT3=9, pT4=10); 25 patients were pN-positive. All tumors were histologically analyzed regarding PLI (present or not) and the tumor border (sharp or infiltrating). Based on standardized CT examinations (90 ml contrast agent at 1.5 ml/s), repeated region-of-interest (ROI)-based peritumoral density measurements were obtained. Correlations between CT density, PLI, tumor border and metastatic involvement of regional lymph nodes were statistically evaluated. CT densities were significantly higher (P

Invasive coronary angiography is the gold standard for the primary diagnosis of coronary artery disease (CAD). At most, only every other examination leads to revascularization therapy. The other coronary angiographies could be replaced by non-invasive examinations. Diagnosing CAD by cardiac MRI and CT can utilize three different strategies: detection of coronary calcifications; imaging of coronary artery stenoses; and detection of restricted myocardial perfusion reserve. Applications are coronary calcification scoring by CT, coronary angiography by MRI or CT, stress cine MRI, and stress perfusion MRI. All these methods are currently used clinically because of their high negative predictive value, i.e., a normal result mostly rules out a hemodynamically significant CAD. For a reasonable implication in clinical practice, however, the pre-test probability must be considered to avoid needless examinations. High pre-test probability invariably demands invasive coronary angiography for planning or performing revascularization therapy. Intermediate pre-test probability, on the contrary, justifies to defer further imaging studies if MRI or CT is normal. Thus, adequate selection of patients for cardiac MRI and CT may reduce the number of invasive coronary angiographies in the future.

Objectives The purpose of the present study was to measure absolute concentrations of phosphocreatine (PCr) and adenosine triphosphate (ATP) in normal, hypertrophied, and failing human heart. Background Conflicting evidence exists on the extent of changes of high-energy phosphate metabolites in hypertrophied and failing human heart. Previous reports using phosphorus-31 magnetic resonance spectroscopy ( 31 P-MRS) have quantified metabolites in relative terms only. However, this analysis cannot detect simultaneous reductions. Methods Four groups of subjects (n = 10 each), were studied: volunteers and patients with hypertensive heart disease (HHD), aortic stenosis, and dilated cardiomyopathy (DCM). Left ventricular (LV) function and mass were measured by cine magnetic resonance imaging. Absolute and relative concentrations of PCr and ATP were determined by 31 P-MRS with spatial localization with optimum pointspread function. Results Left ventricular ejection fraction remained normal in HHD and aortic stenosis, but was severely reduced to 18% in DCM; LV mass was increased by 55%, 79%, and 68% respectively. In volunteers, PCr and ATP concentrations were 8.82 ± 1.30 mmol/kg wet weight and 5.69 ± 1.02 mmol/kg wet weight, and the PCr/ATP ratio was 1.59 ± 0.33. High-energy phosphate levels were unaltered in HHD. In aortic stenosis, PCr was decreased by 28%, whereas ATP remained constant. In DCM, PCr was reduced by 51%, ATP by 35%, and reduction of the PCr/ATP ratio by 25% was of borderline significance (p = 0.06). Significant correlations were observed among energetic and functional variables, with the closest relations for PCr. Conclusions In human heart failure due to DCM, both PCr and ATP are significantly reduced. Ratios of PCr to ATP underestimate changes of high-energy phosphate levels.