Jens Figiel

Occurrence of late gadolinium enhancement is associated with increased left ventricular wall stress and mass in patients with non-ischaemic dilated cardiomyopathy.

Occurrence of late gadolinium enhancement (LGE) as assessed by cardiac magnetic resonance (CMR) imaging has been attributed to various myocardial injuries. We hypothesized that LGE is associated with left ventricular (LV) wall stress.

Increased enddiastolic wall stress precedes left ventricular hypertrophy in dilative heart failure—Use of the volume-based wall stress index

INTRODUCTION To examine a potential interrelation of left ventricular (LV) wall stress and hypertrophy, we assessed increased wall stress in patients with suspected non-ischemic dilative cardiomyopathy and addressed the question whether increased LV wall stress is involved in the development of LV hypertrophy. METHODS We studied 502 consecutive patients in whom LV mass, LV enddiastolic (LVEDV) and endsystolic volume (LVESV) was determined using cardiac magnetic resonance (CMR). Based on a thick-walled sphere, we introduced a myocardial and cavity volume-based wall stress index. Follow up CMR examinations were obtained in a representative subgroup of 71 patients. RESULTS LV mass was correlated with LVEDV (r=0.517, P<0.001) and LVESV (r=0.510, P<0.001). Despite LV hypertrophy, LV mass was not sufficient to compensate for LV dilatation resulting in an increased wall stress. Increased LV enddiastolic wall stress was found in 227 patients (45 %) and increased endsystolic wall stress in 198 (39 %). In patients with normal LV enddiastolic wall stress ≤ 4 kPa at time of enrolment, no changes of LV mass occurred during follow up (142 ± 46 g vs. 141 ± 47 g). In contrast, patients with initially increased LV enddiastolic wall stress >4 kPa developed greater LV hypertrophy (141 ± 48 g vs. 158 ± 60 g, P=0.0247). CONCLUSIONS LV wall stress can be derived from CMR measurements of LV myocardium and cavity using the volume-based wall stress index. Increased LV enddiastolic wall stress leads to LV hypertrophy. Beyond a certain degree of LV dilatation, the extent of hypertrophy does not compensate LV dilatation. The ensuing increased wall stress promotes dilatation and consecutively hypertrophy with an unfavorable prognosis. It is proposed to use the volume-based wall stress index as new diagnostic criterion in heart failure.

Height restoration and maintenance after treating unstable osteoporotic vertebral compression fractures by cement augmentation is dependent on the cement volume used.

BACKGROUND Two different procedures, used for percutaneous augmentation of vertebral compression fractures were compared, with respect to height restoration and maintenance after cyclic loading. Additionally the impact of the cement volume used was investigated. METHODS Wedge compression fractures were created in 36 human cadavaric vertebrae (T10-L3). Twenty-seven vertebrae were treated with the SpineJack® with different cement volumes (maximum, intermediate, and no cement), and 9 vertebrae were treated with Balloon Kyphoplasty. Vertebral heights were measured pre- and postfracture as well as after treatment and loading. Cyclic loading was performed with 10,000cycles (1Hz, 100-600N). FINDINGS The average anterior height after restoration was 85.56% for Kyphoplasty; 96.20% for SpineJack® no cement; 93.44% for SpineJack® maximum and 96% for the SpineJack® intermediate group. The average central height after restoration was 93.89% for Kyphoplasty; 100.20% for SpineJack® no cement; 99.56% for SpineJack® maximum and 101.13% for the SpineJack® intermediate group. The average anterior height after cyclic loading was 85.33 % for Kyphoplasty; 87.30% in the SpineJack® no cement, 92% in the SpineJack® maximum and 87% in the SpineJack® intermediate group. The average central height after cyclic loading was 92% for Kyphoplasty; 93.80% in the SpineJack® no cement; 98.56% in the SpineJack® maximum and 94.25% in the SpineJack® intermediate group. INTERPRETATION Height restoration was significantly better for the SpineJack® group compared to Kyphoplasty. Height maintenance was dependent on the cement volume used. The group with the SpineJack® without cement nevertheless showed better results in height maintenance, yet the statistical significance could not be demonstrated.

Height restoration of osteoporotic vertebral compression fractures using different intravertebral reduction devices: a cadaveric study

BACKGROUND The treatment of osteoporotic vertebral compression fractures using transpedicular cement augmentation has grown significantly during the past two decades. Balloon kyphoplasty was developed to restore vertebral height and improve sagittal alignment. Several studies have shown these theoretical improvements cannot be transferred universally to the clinical setting. PURPOSE The aim of the current study is to evaluate two different procedures used for percutaneous augmentation of vertebral compression fractures with respect to height restoration: balloon kyphoplasty and SpineJack. MATERIALS AND METHODS Twenty-four vertebral bodies of two intact, fresh human cadaveric spines (T6-L5; donor age, 70 years and 60 years; T-score -6.8 points and -6.3 points) were scanned using computed tomography (CT) and dissected into single vertebral bodies. Vertebral wedge compression fractures were created by a material testing machine (Universal testing machine, Instron 5566, Darmstadt, Germany). The axial load was increased continuously until the height of the anterior edge of the vertebral body was reduced by 40% of the initial measured values. After 15 minutes, the load was decreased manually to 100 N. After postfracture CT, the clamped vertebral bodies were placed in a custom-made loading frame with a preload of 100 N. Twelve vertebral bodies were treated using SpineJack (SJ; Vexim, Balma, France), the 12 remaining vertebral bodies were treated with balloon kyphoplasty (BKP; Kyphon, Medtronic, Sunnyvale, CA, USA). The load was maintained during the procedure until the cement set completely. Posttreatment CT was performed. Anterior, central, and posterior height as well as the Beck index were measured prefracture and postfracture as well as after treatment. RESULTS For anterior height restoration (BKP, 0.14±1.48 mm; SJ, 3.34±1.19 mm), central height restoration (BKP, 0.91±1.04 mm; SJ, 3.24±1.22 mm), and posterior restoration (BKP, 0.37±0.57 mm; SJ, 1.26±1.05), as well as the Beck index (BKP, 0.00±0.06 mm; SJ, 0.10±0.06), the values for the SpineJack group were significantly higher (p<.05) CONCLUSION: The protocols for creating wedge fractures and using the instrumentation under a constant preload of 100 N led to reproducible results and effects. The study showed that height restoration was significantly better in the SpineJack group compared with the balloon kyphoplasty group. The clinical implications include a better restoration of the sagittal balance of the spine and a reduction of the kyphotic deformity, which may relate to clinical outcome and the biological healing process.

Prospective comparison of image quality and diagnostic accuracy of 0.5 molar gadobenate dimeglumine and 1.0 molar gadobutrol in contrast-enhanced run-off magnetic resonance angiography of the lower extremities†

To compare image quality and diagnostic accuracy of 0.5 molar gadobenate dimeglumine and 1.0 molar gadobutrol in contrast‐enhanced (CE) magnetic resonance angiography (MRA) of the lower extremities interindividually.

Association of hyperhomocysteinemia with left ventricular dilatation and mass in human heart.

Abstract Background: Hyperhomocysteinemia is a risk factor for ischemic heart disease. Several other mechanisms apply also to dilative types of heart failure of various, non-ischemic etiologies. We hypothesized that hyperhomocysteinemia is associated with left ventricular (LV) dilatation and hypertrophy in dilative cardiomyopathy. Methods: Homocysteine was measured in 66 individuals with suspected cardiomyopathy. Cardiac magnetic resonance imaging was used to assess LV volume, mass, and wall stress. Results: Hyperhomocysteinemia (>12 μmol/L) was found in 45 patients (68%). LV mass was greater in these patients compared with individuals with normal homocysteine (83±27 vs. 67±19 g/m2; p<0.02). Homocysteine was increased in patients with increased brain natriuretic peptide ≥100 pg/mL (18.3±5.9 vs. 14.9±5.1 μmol/L; p=0.018). LV mass, LV end-diastolic and end-systolic volume (LVEDV, LVESV) were significantly increased in individuals in the upper quartile compared with the lower quartile (90±25 vs. 65±18 g/m2, p=0.021; 114±50 vs. 71±23 mL/m2, p=0.042; 76±51 vs. 36±22 mL/m2, p=0.045). LV dilatation (LVEDV≥90 mL/m2) was more common in hyperhomocysteinemia (>12 μmol/L, p=0.0166). Normalized LV mass was correlated with homocysteine (r=0.346, p=0.065). Homocysteine was not significantly correlated with LVEDV (r=0.229, p=0.065), LV end-diastolic wall stress (r=0.226, p=0.069) and LV ejection fraction. Conclusions: Hyperhomocysteinemia appears to be, at least in part, involved in a disproportional LV dilatation, where the ensuing hypertrophy is not sufficient to compensate for the increased wall stress. A potential mechanism is the hyperhomocysteinemia associated increase in oxidative stress that favors muscle fiber slippage. Clin Chem Lab Med 2010;48:555–60.

Increased ventricular wall stress and late gadolinium enhancement in Takotsubo cardiomyopathy.

difference and peripheral vascular disease: cross-sectional study. Fam Pract 2007;24:5420–6. [3] Clark CE, Taylor RS, Shore AC, Ukoumunne OC, Campbell JL. Association of a difference in systolic blood pressure between arms with vascular disease and mortality: a systematic review and meta-analysis. Lancet 2012;379:905–14. [4] Sun H, Li P, Su H, et al. The detection rates of inter-arm systolic blood pressure difference vary with blood pressure levels in hypertensive patients under antihypertensive therapy. Int J Cardiol Jan 1

Enhancing Same-Day Access to Magnetic Resonance Imaging

PURPOSE The aim of this study was to provide better patient access to MRI within 24 hours through process improvement. METHODS The MRI process in an academic radiology department was examined. Customer value was determined using a Kano questionnaire. Current state process and performance data were measured. Process time and process value mapping were conducted. Underlying root causes that hampered MRI process flow were identified and prioritized using a fishbone diagram and failure mode and effect analysis. Statistical analysis, queuing theory, and statistical process control were used to describe and understand process behaviors, to test hypotheses, to validate solutions, and to monitor results. RESULTS Timely access to MRI examinations within 24 hours was identified as a key customer value. A total of 33 failure modes leading to process wastes, together with 113 potential failure causes, were worked out, of which 14 failure modes were prioritized and dealt with. Having improved the process, patient access within 24 hours increased from 53% to >90%. The mean cycle time was reduced from 52 to 39 minutes. The monthly throughput increased by 38%. Scanner productivity was increased by 32%. Revenue and savings are estimated to be about €247,000 in the first year, after subtracting all costs. CONCLUSIONS Patient access to MRI within 24 hours has been granted for >90% of requests. Improved productivity and cost saving are achieved simultaneously.

Wall stress determines systolic and diastolic function — Characteristics of heart failure

INTRODUCTION Heart failure can be caused by systolic or diastolic dysfunction. Diagnosing diastolic dysfunction remains challenging, although several criteria have been identified. Ventricular wall stress is crucially involved. It is hypothesized whether increased end-diastolic and end-systolic ventricular wall stress as assessed by the wall stress index is associated with cardiac dysfunction and thus provide novel diagnostic criteria. METHODS 1050 consecutive patients with suspected non-ischemic heart failure covering a broad spectrum from normal to severely impaired cardiac function were observed. Cardiac magnetic resonance imaging was performed to assess left ventricular (LV) volumes, myocardial mass, peak ejection (PER) and filling rate (PFR). RESULTS A reduced PFR was found in 348 patients (33.1%), which resulted from 275 of 422 patients (65.2%) with reduced and from 73 of 628 patients (11.6%) with preserved LVEF (p<0.0001). Increased LV volume and mass was correlated with reduced PER and PFR (p<0.0001). Increased end-diastolic wall stress was the strongest predictor of a reduced PER (OR 4.5 [2.6 to 7.8], p<0.0001) and increased end-systolic wall stress predicted a reduced PFR (OR 1.2 [1.1 to 1.3], p<0.0001). Increased end-systolic wall stress was correlated with increased pulmonary pressure (p<0.0001). Normal end-systolic wall stress<18 kPa had a favorable predictive value for the absence of an impaired filling and increased pulmonary capillary pressure. CONCLUSION Increased end-diastolic wall stress precedes a reduced ventricular ejection rate and increased end-systolic wall stress determines an impaired diastolic filling. It is thus suggested to add assessment of ventricular wall stress as diagnostic criterion of heart failure.

MRI after unicondylar knee arthroplasty: rotational alignment of components

IntroductionThis pilot study used magnet resonance imaging (MRI) to analyse the rotation of medial unicondylar knee arthroplasty (UKA) components and assessed how accurately the results could be reproduced.Materials and methodsKnee MRI using a special protocol to reduce metal artefact was performed in ten patients who had undergone medial UKA. Two independent investigators measured the rotation angle of femoral (zirconium) and tibial (cemented full-poly or cemented modular metal-backed) components applying different reference lines for the latter. Statistical analysis comprised tests for reliability, variance between measurement techniques, standard deviations and limits of agreement.ResultsFor all methods tested, there was sufficient inter- and intra-observer reliability. Lowest variances were, however, found for the femoral epicondyles, for both femoral and tibial components. A tangent to the dorsal epicondyles of the tibia also gave reproducible results with low variances for the tibial component.DiscussionAlmost all applied measurement techniques were reproducible by statistical definition, although some of them resulted in substantial differences between both, observations and observers. A variance test helps to distinguish better between clinically useful and less accurate references.ConclusionMRI allows good reproducible rotation analysis via the femoral epicondyles for both femoral and tibial UKA implants. For the tibia, the tibial tuberosity, the eminentia and the tibial epicondyles in particular were shown to be less reliable. The dorsal epicondyles seem to be most suitable for the tibial component.