Biomedical subjects

Balthasar Eberle

Publications and source records attributed to Balthasar Eberle.

At least 19 recordsLinked to original sources

PubMed2006

Chronic thromboembolic pulmonary hypertension - assessment by magnetic resonance imaging.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a severe disease that has been ignored for a long time. However, with the development of improved therapeutic modalities, cardiologists and thoracic surgeons have shown increasing interest in the diagnostic work-up of this entity. The diagnosis and management of chronic thromboembolic pulmonary hypertension require a multidisciplinary approach involving the specialties of pulmonary medicine, cardiology, radiology, anesthesiology and thoracic surgery. With this approach, pulmonary endarterectomy (PEA) can be performed with an acceptable mortality rate. This review article describes the developments in magnetic resonance (MR) imaging techniques for the diagnosis of chronic thromboembolic pulmonary hypertension. Techniques include contrast-enhanced MR angiography (ce-MRA), MR perfusion imaging, phase-contrast imaging of the great vessels, cine imaging of the heart and combined perfusion-ventilation MR imaging with hyperpolarized noble gases. It is anticipated that MR imaging will play a central role in the initial diagnosis and follow-up of patients with CTEPH.

Chronic Disease↗

PubMed2005

Inhaled iloprost to control residual pulmonary hypertension following pulmonary endarterectomy.

OBJECTIVE: Pulmonary endarterectomy (PEA) is the standard therapy for patients with chronic thromboembolic pulmonary hypertension (CTEPH). In the immediate postoperative period, persistent pulmonary hypertension increases the risk of acute respiratory or right heart failure. In pulmonary arterial hypertension, prostanoid inhalation has been found to improve pulmonary hemodynamics, right ventricular function, gas exchange, and clinical outcome. We report the results of a double-blinded randomized trial with the aerosolized prostacyclin analogue iloprost in patients with residual pulmonary hypertension after PEA. METHODS: Twenty-two patients (age, 55+/-13 years; 8 females; propofol- and sufentanil-based anesthesia; pressure-controlled mechanical ventilation) were randomized to receive either a single dose of 25 microg aerosolized iloprost (iloprost group; n=11) or normal saline (placebo group; n=11) immediately after postoperative ICU admission. Primary endpoints were changes in gas exchange, pulmonary and systemic hemodynamics, and clinical outcome. RESULTS: Iloprost significantly enhanced cardiac index (CI) and reduced mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance [PVR (dynscm(-5))] in contrast to placebo. Placebo: pre-inhalation 413+/-195 versus post-inhalation 404+/-196 at 30 min (p=0.051), 415+/-189 at 90 min (p=0.929). Iloprost: pre-inhalation 503+/-238 versus post-inhalation 328+/-215 at 30 min (p=0.001), 353+/-156 at 90 min (p=0.003). Blood oxygenation remained unchanged. CONCLUSION: In addition to the effect of PEA, iloprost reduces residual postoperative pulmonary hypertension, decreases right ventricular afterload and may facilitate the early postoperative management after PEA.

Administration, Inhalation↗

PubMed2005

Two-dimensional and three-dimensional oxygen mapping by 3He-MRI validation in a lung phantom.

The aim of this study was to validate oxygen-sensitive 3He-MRI in noninvasive determination of the regional, two- and three-dimensional distribution of oxygen partial pressure. In a gas-filled elastic silicon ventilation bag used as a lung phantom, oxygen sensitive two- and three-dimensional 3He-MRI measurements were performed at different oxygen concentrations which had been equilibrated in a range of normal and pathologic values. The oxygen partial pressure distribution was determined from 3He-MRI using newly developed software allowing for mapping of oxygen partial pressure. The reference bulk oxygen partial pressure inside the phantom was measured by conventional respiratory gas analysis. In two-dimensional measurements, image-based and gas-analysis results correlated with r=0.98; in three-dimensional measurements the between-methods correlation coefficient was r=0.89. The signal-to-noise ratio of three-dimensional measurements was about half of that of two-dimensional measurements and became critical (below 3) in some data sets. Oxygen-sensitive 3He-MRI allows for noninvasive determination of the two- and three-dimensional distribution of oxygen partial pressure in gas-filled airspaces.

Helium↗

PubMed2005

Analysis of discrete and continuous distributions of ventilatory time constants from dynamic computed tomography.

In this study, an algorithm was developed to measure the distribution of pulmonary time constants (TCs) from dynamic computed tomography (CT) data sets during a sudden airway pressure step up. Simulations with synthetic data were performed to test the methodology as well as the influence of experimental noise. Furthermore the algorithm was applied to in vivo data. In five pigs sudden changes in airway pressure were imposed during dynamic CT acquisition in healthy lungs and in a saline lavage ARDS model. The fractional gas content in the imaged slice (FGC) was calculated by density measurements for each CT image. Temporal variations of the FGC were analysed assuming a model with a continuous distribution of exponentially decaying time constants. The simulations proved the feasibility of the method. The influence of experimental noise could be well evaluated. Analysis of the in vivo data showed that in healthy lungs ventilation processes can be more likely characterized by discrete TCs whereas in ARDS lungs continuous distributions of TCs are observed. The temporal behaviour of lung inflation and deflation can be characterized objectively using the described new methodology. This study indicates that continuous distributions of TCs reflect lung ventilation mechanics more accurately compared to discrete TCs.

Algorithms↗

PubMed2005

A novel technique to follow fast PaO2 variations during experimental CPR.

OBJECTIVE: An ultrafast responding fluorescent-quenching PO2 probe allows time-resolved, in vivo measurement of PO2. This study describes several validation experiments of this new device in vitro, and reports its first use during cardiopulmonary resuscitation in an animal model of cardiac arrest. METHODS: The influence of CO2, temperature and motion artefacts on the signal response of the PO2 probe was analysed in vitro by systematic variation of these values. Thereafter, with approval of the Review Board for the care and use of animals, CPR was performed in four pigs. The PaO2 course was recorded continuously at time resolution of <80 ms in the abdominal aorta using an uncoated fluorescence-quenching probe (Foxy AL-300, OceanOptics Inc., USA). RESULTS: In vitro experiments showed that signal intensity is dependent on CO2 concentration (DeltaPfaO2=4 mmHg/vol.% CO2) and temperature (DeltaPfaO2=16 mmHg/ degrees C), but it is robust with regards to probe motion. In the animal experiments, the uncoated fluorescence-quenching probe was calibrated by repeated simultaneous measurements with the Paratrend 7 sensor to correct the PfaO2 for a potential signal drift, PCO2 and temperature variations. In all animal experiments, the individual PaO2 courses were clearly related to therapeutic interventions and their haemodynamic effects during CPR and allowed recording of ultrafast PO2 changes with a time resolution of 80 ms. CONCLUSIONS: The results demonstrate the feasibility of ultrafast PO2 measurement during CPR and low-flow states. They also demonstrate very rapid systemic effects of CPR upon aortic PO2. Among many other useful applications, the information derived from this technique may help to define the optimum conditions for successful defibrillation and restoration of spontaneous circulation.

Animals↗

PubMed2005

Experimental stenting of the posterior mitral leaflet to correct prolapse in mitral valve insufficiency.

OBJECTIVE: This study investigated the use of a new concept of mitral valve reconstruction using a novel device to stent the posterior mitral leaflet in combination with semicircular annuloplasty. Modern mitral valve repair is an accepted modality and a routine procedure for treatment of degenerative mitral valve insufficiency. One of the most common mechanisms of mitral valve insufficiency is leaflet prolapse. In the majority of cases the posterior leaflet is dysfunctional and therapeutic reconstruction of the PII flail leaflet segment involves quadrangular resection which is usually combined to mitral annulo-plasty with a ring. A new time-saving concept of mitral valve reconstruction by stenting the posterior mitral leaflet in combination with semicircular annuloplasty is presented. METHODS: The new mitral valve reconstruction device (Shelhigh MitroFast, Shelhigh, Inc., Union, NJ, USA) was implanted in four adult sheep. It is constructed as an annuloplasty ring in combination with a posterior leaflet stent. The device has the shape of a closed posterior leaflet and forms a "buttress" against which the anterior leaflet can coapt. RESULTS: Every implantation of a MitroFast device could be performed in less than 30 minutes. After implantation of the device, all animals could be successfully weaned from CPB. Invasively measured left atrial pressure was below 12 mm Hg in all animals. After chest closure, transoesophageal echocardiography revealed a competent mitral valve in all animals, without any inflow restriction in three animals, and suspected mild stenosis in one animal. CONCLUSIONS: In this experimental model, implantation of the newly designed annuloplasty ring with stenting the posterior mitral leaflet avoids extensive and time-consuming reconstructive surgery on a flail posterior leaflet. Implantation of the device resulted in favorable short-term hemodynamic effects. Implantation technique of the device is simple, the potential for minimal invasive implantation of a conceptual similar device will be further investigated.

Animals↗

PubMed2004

Functional evaluation of emphysema using diffusion-weighted 3Helium-magnetic resonance imaging, high-resolution computed tomography, and lung function tests.

PURPOSE: To assess the emphysematous enlargement of distal airspaces and concomitant large and small airway disease using diffusion-weighted Helium-magnetic resonance imaging (MRI), high-resolution computed tomography (HRCT), and lung function tests (LFT). METHODS: Seven patients were examined after single lung transplantation (LTx) and 1 before double LTx for various forms of emphysema. Five patients after double LTx served as controls. Patients were assessed by Helium-MRI (apparent diffusion coefficient [ADC]), HRCT (mean lung density [MLD], emphysema index [EI]), and LFT. RESULTS: Transplanted lungs: mean ADC = 0.17 cm/s, MLD = -848 H, EI = 22%. Emphysematous lungs: mean ADC = 0.33 cm/s, MLD = -922 H; EI = 54%. Good correlations were found between ADC and MLD (r = 0.6), EI (r = 0.8), intrathoracic gas volume (r = 0.7), forced expiratory volume in 1 second (r = 0.7), and forced expiratory flows (r = 0.7). In contrast, HRCT only provided moderate correlations with LFT (EI: r = 0.5; MLD: r [le] 0.4). CONCLUSION: In this initial study, He-MRI yield good correlations with HRCT and agrees better than HRCT with the functional characterization of emphysema regarding hyperinflation, large and small airway disease as provided by LFT.

Female↗

PubMed2004

Functional analysis in single-lung transplant recipients: a comparative study of high-resolution CT, 3He-MRI, and pulmonary function tests.

OBJECTIVE: To develop and evaluate a postprocessing tool to quantify ventilated split-lung volumes on the basis of (3)He-MRI and to apply it in patients after single-lung transplantation (SLTX). High-resolution CT (HRCT) was employed as a reference modality providing split air-filled lung volumes. Lung volumes derived from pulmonary function test results served as clinical parameters and were used as the "gold standard." MATERIAL AND METHODS: Eight patients (mean age, 54 years) with emphysema and six patients (mean age, 58 years) with idiopathic pulmonary fibrosis. All patients were evaluated following SLTX. HRCT was performed during inspiration (slice thickness, 1 mm; increment, 10 mm). For correlation with (3)He-MRI, HRCT images were reconstructed in coronal orientation to match the same anatomic levels. Aerated lung was determined by threshold-based segmentation of CT. (3)He-MRI was performed on a 1.5-T scanner using a two-dimensional, fast low-angle shot sequence in coronal orientation covering the whole lung after inhalation of a 300-mL bolus of hyperpolarized (3)He gas followed by normal room air for the rest of the tidal volume. Lung segmentation on (3)He-MRI was done using different thresholds. RESULTS: In emphysematous patients, (3)He-MRI showed excellent correlation (r = 0.9) with vital capacity, while CT correlated (r = 0.8) with total lung capacity. (3)He-MRI correlated well with CT (r > 0.8) for grafts and native fibrotic lungs. In emphysematous lungs, MRI showed a good correlation (r = 0.7) with the nonemphysematous lung volume from CT. Increasing thresholds in (3)He-MRI reveal differences between aerated and ventilated lung areas with a different distribution in emphysema and fibrosis. CONCLUSIONS: (3)He-MRI is superior to CT in emphysema to demonstrate ventilated lung areas that participate in gas exchange. In fibrosis, (3)He-MRI and CT have a similar impact. The decrease pattern and the intraindividual ratio between ventilation of native and transplanted lungs will have to be investigated as a new surrogate for the ventilatory follow-up in patients undergoing SLTX.

Female↗

PubMed2003

(3)He-MRI in follow-up of lung transplant recipients.

The aim of this study was to evaluate the possible contribution of (3)He-MRI to detect obliterative bronchiolitis (OB) in the follow-up of lung transplant recipients. Nine single- and double-lung transplanted patients were studied by an initial and a follow-up (3)He-MRI study. Images were evaluated subjectively by estimation of ventilation defect area and quantitatively by individually adapted threshold segmentation and subsequent calculation of ventilated lung volume. Bronchiolitis obliterans syndrome (BOS) was diagnosed using pulmonary function tests. At (3)He-MRI, OB was suspected if ventilated lung volume had decreased by 10% or more at the follow-up MRI study compared with the initial study. General accordance between pulmonary function testing and (3)He-MRI was good, although subjective evaluation of (3)He-MRI underestimated improvement in ventilation as obtained by pulmonary function tests. The (3)He-MRI indicated OB in 6 cases. According to pulmonary function tests, BOS was diagnosed in 5 cases. All diagnoses of BOS were also detected by (3)He-MRI. In 2 of these 5 cases, (3)He-MRI indicated OB earlier than pulmonary function tests. The results support the hypothesis that (3)He-MRI may be sensitive for early detection of OB and emphasize the need for larger prospective follow-up studies.

Adult↗

PubMed2003

High-frequency oscillatory ventilation in adult acute respiratory distress syndrome.

OBJECTIVE: This study examined whether ARDS patients in whom predefined ventilator settings fail to maintain oxygenation and CO2 removal can be safely transitioned to high-frequency oscillatory ventilation (HFOV), and whether HFOV use is efficacious. DESIGN AND SETTING: Prospective observational study in the 14-bed intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: 42 patients with ARDS (APACHE II score 28 (IQR 24-37) and ventilation time prior HFOV 3.0 days (0.7-9.1). MEASUREMENTS AND RESULTS: Gas exchange parameters and ventilator data were recorded before and during HFOV treatment (-12 h, -6 h, baseline, 10 min, 1 h, 6 h, 12 h, 24 h). Primary endpoints included: (a) PaO2/FIO2 ratio 24 h after start of HFOV treatment or the last point of measurement if HFOV ended within the first 24 h; (b) HFOV-related complications. Post hoc analysis assessed the relationship between outcome and the response to HFOV, and between outcome and time of mechanical ventilation prior to HFOV. At baseline the median PaO2/FIO2 ratio was 95 (IQR 62-129); after 24 h of HFOV the PaO2/FIO2 ratio had increased significantly to 165 (88-225); only one patient developed a unilateral pneumothorax. Of the 42 patients 18 (43%) had died by day 30. Subset analyses showed a significantly higher 30-day mortality rate in patients with at least 3 days of mechanical ventilation prior to HFOV (64%) and in patients without oxygenation improvement after 24 h on HFOV (71%). CONCLUSIONS: HFOV is an effective and safe method to ventilate ARDS patients. Failure to improve oxygenation within 24 h of HFOV is associated with high mortality.

Adult↗

PubMed2003

Inhaled iloprost in patients with chronic thromboembolic pulmonary hypertension: effects before and after pulmonary thromboendarterectomy.

BACKGROUND: In primary pulmonary hypertension, aerosolized prostanoids selectively reduce pulmonary vascular resistance and improve right ventricular function. In this study, hemodynamic effects of inhaled iloprost, a stable prostacyclin analogue, were evaluated in patients with chronic thromboembolic pulmonary hypertension (CTEPH) before and early after pulmonary thromboendarterctomy (PTE). METHODS: Ten patients (mean age 49 years old [32 to 70 years old], New York Heart Association functional class III and IV) received a dose of 33 micro g aerosolized iloprost immediately before surgery (T1), after intensive care unit admission (T2), and 12-hours postoperatively (T3). Effects on pulmonary and systemic hemodynamics and gas exchange were recorded and compared with preinhalation baseline values. RESULTS: Preoperatively, inhaled iloprost did not significantly change mean pulmonary artery pressure (mPAP), cardiac index (CI), or pulmonary vascular resistance (PVR). Postoperatively, inhaled iloprost induced a significant reduction of mPAP and PVR and a significant increase of CI at T2 and T3. Preinhalation versus postinhalation PVR was as follows: at T1, 847 versus 729 dynes. s. cm(-5), p = 0.45; at T2, 502 versus 316 dynes. s. cm(-5), p = 0.008; and at T3, 299 versus 227 dynes. s. cm(-5), p = 0.004. CONCLUSIONS: In patients with CTEPH, inhalation of iloprost elicits no significant pulmonary vasodilation before surgery, and may have detrimental effects on systemic hemodynamics. Postoperatively, it significantly reduces mPAP and PVR, and enhances CI. Following PTE, inhalation of iloprost is useful to improve early postoperative hemodynamics.

Administration, Inhalation↗

PubMed2003

Magnetic resonance imaging using hyperpolarized 3He-Gas.

RATIONALE AND OBJECTIVES: Current imaging procedures of the lung concentrate on visualization of morphology. Computed tomography is the imaging method of choice for the majority of pulmonary diseases. Functional data are commonly obtained from arterial blood gas analysis, spirometry, and body plethysmography, which all suffer from lack of regional information. MATERIALS AND METHODS: Magnetic resonance imaging (MRI) of the lung has been advanced recently by the use of hyperpolarized 3He as a new contrast mechanism. Four different image acquisition modes are performed during a typical patient study. RESULTS: 3He-MRI yields functional information about the lung with a high spatial and temporal resolution, avoiding the risks of ionizing radiation. The method is currently limited by high costs and restricted availability of the gas. CONCLUSION: In this article, the experience obtained at the University of Mainz, being Europe's most experienced center performing 3He-MRI in humans, is reviewed against the international background.

Contrast Media↗

PubMed2003

Distribution of ventilation in lung transplant recipients: evaluation by dynamic 3He-MRI with lung motion correction.

RATIONALE AND OBJECTIVES: The ability of motion corrected dynamic 3He-magnetic resonance imaging (MRI) to discriminate distributional patterns of inhaled hyperpolarized 3He between different groups of lung transplant recipients was evaluated. METHODS: An ultrafast low-angle shot 2D sequence (temporal resolution 128 ms) was used for ventilation 3He-MRI of 11 single and 6 double lung transplant recipients. After digital motion correction, signal kinetics were evaluated in a tracheal and 7 pulmonary regions of interest. Results from grafts and native lungs as well as from normal and rejected grafts were compared with each other and to reference values from healthy subjects. RESULTS: In emphysema patients, median alveolar rise time, a parameter for increase of alveolar signal, was 0.28 seconds for the graft and 0.48 seconds for the native lung, in fibrosis patients its median was 0.46 seconds for the graft and 0.21 seconds for the native lung. In double lung recipients, alveolar rise time was 0.29 seconds in normal and clinically rejected grafts. CONCLUSIONS: Dynamic ventilation 3He-MRI discriminated normal lung grafts from diseased native lungs in single lung recipients. Graft rejection in double lung recipients could not be discriminated.

Female↗

PubMed2002

[Endovascular aneurysm therapy--long-term treatment outcomes after 7 years].

BACKGROUND: Stentgrafts for endovascular treatment of abdominal aortic aneurysms (AAA) have been commercially available since 1994, with now large numbers of implantations all over the world. PATIENTS AND METHODS: From 1994-2001, 115 patients were treated with Stentor, Vanguard and Talent stentgrafts in our institution. RESULTS: Late complications of the first- and second-generation stentgrafts as radiologic or surgical interventions to maintain complete exclusion of the aneurysm amounted to 30% with an additional 22% for observed endoleaks and configuration changes of the stentgraft. Third-generation stentgrafts had a lower complication rate of 12.2% for interventions and 18.3% for late endoleaks and graft changes. CONCLUSION: High costs of the devices, a pretty high late complication rate, and the uncertain maintenance of stentgraft function to prevent aneurysm rupture currently limit the widespread application of this new technology, leaving conventional aneurysmectomy the standard for aneurysm treatment and reserving the endovascular method for selected patients.

Aged↗

PubMed2002

MRI in lung transplant recipients using hyperpolarized 3He: comparison with CT.

PURPOSE: To elucidate the ability of 3He-MRI to detect ventilation defects in lung transplant recipients, 3He-MRI was compared to CT for concordance. MATERIALS AND METHODS: We examined 14 lung recipients using 3He-MRI on a 1.5 T MR scanner. CT served as a reference method. Up to four representative ventilation defects were defined for each lung on 3He-MRI and compared to corresponding areas on CT. RESULTS: Altogether, 59 representative ventilation defects were defined on 3He-MRI. Plausible CT correlates were found for 29 ventilation defects; less plausible CT correlates were found for eight defects. In 22 defects (37%) no corresponding CT changes were detected. CT demonstrated correlates for ventilation defects seen on 3He-MRI in only 63% of the cases. CONCLUSION: 3He-MRI yields a clear increase in the number of detected ventilation defects compared to CT. This may have an important impact on the early detection of bronchiolitis obliterans in lung transplant recipients.

Adult↗

PubMed2002

19F-MRI of perflubron for measurement of oxygen partial pressure in porcine lungs during partial liquid ventilation.

A method for in vivo measurement of oxygen partial pressure (pO2) in porcine lungs during partial liquid ventilation (PLV) with perflubron (PFOB) was developed. A pulse sequence for high-resolution MRI of the distribution of PFOB in the lung after intratracheal administration was developed as well. Moreover, quantitative measurements of longitudinal relaxation time T(1) of (19)F resonances for assessment of regional pO2 are described. Due to the need to acquire data during a single expiratory breathhold, only low SNRs were achieved in vivo. Therefore, simulations were performed to investigate the influence of background noise on T(1) values calculated from data with low SNR. Based on these simulations, a postprocessing strategy was developed to correct for systematic errors by background noise prior to quantitative analysis. Results of a pilot study in pigs under conditions of PLV are presented.

Animals↗

PubMed2002

Dynamic computed tomography: a novel technique to study lung aeration and atelectasis formation during experimental CPR.

OBJECTIVE: To develop an image based technique to study the effect of different ventilatory strategies on lung ventilation and alveolar recruitment during cardiopulmonary resuscitation (CPR). DESIGN: (1) Technical development of the following components: (a) construction of an external chest compression device, which does not interfere with CT imaging, and (b) development of a software tool to detect lung parenchyma automatically and to calculate radiological density parameters. (2) Feasibility studies: three strategies of CPR ventilation were performed and imaged in one animal each (pigs, 25 kg): volume-constant ventilation (VCV), no ventilation, or continuous airway pressure (CPAP). One minute after induction of circulatory arrest inside the CT scanner, external chest compressions started at a rate of 100 cpm, and one of the ventilation modes was initiated. After 1 min, intravenous epinephrine was added as a bolus (40 microg/kg), followed by a continuous infusion (13 microg/kg per min). Six minutes later, dynamic CT acquisitions (temporal resolution: 100 ms) commenced. Simultaneously, arterial blood gases, acid base status and haemodynamics were sampled. RESULTS: Using a modified chest compression device, dynamic CT acquisitions are feasible during closed-chest CPR. In three pilot experiments with different ventilation strategies, the dedicated software tool allowed to quantify ventilated, atelectatic and over-distended fractions of total lung area. VCV showed a large amount of atelectasis, which was recruited during every respiratory cycle. No ventilation led to atelectasis to govern over 50% of the total lung area. CPAP caused less atelectasis as VCV, and no cyclic recruitment and de-recruitment phenomena were observed. CONCLUSIONS: We demonstrate a novel experimental set up, which allows quantification of different lung compartments during ongoing CPR and may become useful in comparing the direct pulmonary effects of different ventilatory strategies in the settings of Basic and Advanced Cardiac Life Support.

Animals↗

PubMed2002

Elucidation of structure-function relationships in the lung: contributions from hyperpolarized 3helium MRI.

Magnetic resonance imaging (MRI) using hyperpolarized 3helium (He) gas as the source of signal provides new physiological insights into the structure-function relationships of the lung. Traditionally, lung morphology has been visualized by chest radiography and computed tomography, whereas lung function was assessed by using nuclear medicine. As all these techniques rely on ionizing radiation, MRI has some inherent advantages. 3He MRI is based on 'optical pumping' of the 3He gas which increases the nuclear spin polarization by four to five orders of magnitude translating into a massive gain in signal. Hyperpolarized 3He gas is administered as an inhaled 'contrast agent' and allows for selective visualization of airways and airspaces. Straightforward gas density images demonstrate the homogeneity of ventilation with high spatial resolution. In patients with lung diseases 3He MRI has shown a high sensitivity to depict ventilation defects. As 3He has some more exciting properties, a comprehensive four-step functional imaging protocol has been established. The dynamic distribution of ventilation during continuous breathing can be visualized after inhalation of a single breath of 3He gas using magnetic resonance (MR) sequences with high temporal resolution. Diffusion weighted 3He MRI provides a new measure for pulmonary microstructure because the degree of restriction of the Brownian motion of the 3He atoms reflects lung structure. Since the decay of 3He hyperpolarization is dependent on the ambient oxygen concentration, regional and temporal analysis of intrapulmonary pO2 becomes feasible. Thus, pulmonary perfusion, ventilation /perfusion ratio and oxygen uptake can be indirectly assessed. Further research will determine the significance of the functional information with regard to physiology and patient management.

Animals↗