Quantitative analysis of regional airways obstruction using dynamic hyperpolarized 3He MRI-preliminary results in children with cystic fibrosis.

Purpose: To investigate regional airways obstruction in patients with cystic fibrosis (CF) with quantitative analysis of dynamic hyperpolarized (HP) (3)He MRI.

Materials And Methods: Dynamic radial projection MRI of HP (3)He gas was used to study respiratory dynamics in a group of eight children with CF. Signal kinetics in a total of seven regions of interest (ROIs; three in each lung, and one in the trachea) were compared with the results of spirometric pulmonary function tests (PFTs).

Testosterone therapy in men with moderate severity heart failure: a double-blind randomized placebo controlled trial.

Aims: Chronic heart failure is associated with maladaptive and prolonged neurohormonal and pro-inflammatory cytokine activation causing a metabolic shift favouring catabolism, vasodilator incapacity, and loss of skeletal muscle bulk and function. In men, androgens are important determinants of anabolic function and physical strength and also possess anti-inflammatory and vasodilatory properties.

Methods And Results: We conducted a randomized, double-blind, placebo-controlled parallel trial of testosterone replacement therapy (5 mg Androderm) at physiological doses in 76 men (mean+/-SD, age 64+/-9.

[Hyperpolarized (3)helium gas for functional magnetic resonance imaging of the lung].

Lung imaging is traditionally done using X-ray-based methods, since MRI is limited by low proton density as well as inherent magnetic field inhomogeneities of the lung tissue. After introduction of MRI using hyperpolarized noble gases, a totally new field of MRI of the chest has rapidly evolved. These techniques reveal new functional information of the lungs, which could not be obtained before.

Medial collateral ligament bursitis in a 12-year-old girl.

A 12-year-old female athlete, training for an international career in pentathlon, was referred to our clinic because of 2 years of recurrent localized swelling and activity-related pain in the medial aspect of her right knee, since falling from a horse and hitting her knees on the ground. She had been examined by a number of doctors over this period and treated with physiotherapy without a proper diagnosis and with no improvement. She could run only very limited distances before excruciating pain and swelling, and she had to abandon participation in competitions.

Emphysematous changes and normal variation in smokers and COPD patients using diffusion 3He MRI.

Introduction: This study aims to quantify global and regional changes of diffusive motion of 3He gas within the lung, as determined by hyperpolarized 3He MR apparent diffusion coefficient (ADC) measurement, in non-smokers, smokers and chronic obstructive pulmonary disease (COPD) patients.

Methods: Age-matched groups of six healthy non-smokers, five healthy smokers and five patients with COPD. The experiments were performed with approval from the local Research Ethics Committee.

3D volume-localized pO2 measurement in the human lung with 3He MRI.

A method for 3D volume-localized quantification of pO2 in the lungs is presented that uses repetitive frame 3D gradient-echo imaging of (3)He. The method was demonstrated by experiments on (3)He phantoms containing known concentrations of O(2) and in vivo on a group of three healthy human volunteers. The results were compared with those obtained by equivalent 2D thin-slice and 2D projection methodologies, and were found to be consistent with published results from the 2D projection methodologies (pO(2) = 0.

Measurements and modeling of long range 3He diffusion in the lung using a "slice-washout" method.

In healthy lung tissue, pulsed-gradient-spin-echo (PGSE) methods reveal apparent diffusion coefficients (ADC) of the order 0.20 cm2 s(-1); for diffusion times of approximately 2 ms. For these short diffusion times the ADC is only sensitive to structures approximately (2Dt)1/2 approximately 0.

Combined helium-3/proton magnetic resonance imaging measurement of ventilated lung volumes in smokers compared to never-smokers.

Purpose: To use a combination of helium-3 (3-He) magnetic resonance imaging (MRI) and proton single-shot fast spin echo (SSFSE) to compare ventilated lung volumes in groups of "healthy" smokers, smokers diagnosed with moderate chronic obstructive pulmonary disease (COPD), and never-smokers.

Materials And Methods: All study participants were assessed with spirometry prior to imaging. 3-He images were collected during an arrested breath hold, after inhaling a mixture of 200 mL of hyperpolarized 3-He/800 mL of N2.

Long-term follow-up of patients with suspected deep vein thrombosis of the upper extremity: survival, risk factors and post-thrombotic syndrome.

BACKGROUND: The outcome of upper extremity thrombosis in terms of morbidity, mortality and arm functionality is virtually unknown. We investigated mortality, risk factors, recurrent thrombosis and post-thrombotic syndrome (PTS) in patients with suspected upper extremity thrombosis. METHODS: Consecutive patients suspected of having deep vein thrombosis (DVT) of the upper extremity were followed for up to 53 months (mean 21 months).

Functional MRI of the lung using hyperpolarized 3-helium gas.

Lung imaging has traditionally relied on x-ray methods, since proton MRI is limited to some extent by low proton density in the lung parenchyma and static field inhomogeneities in the chest. The relatively recent introduction of MRI of hyperpolarized noble gases has led to a rapidly evolving field of pulmonary MRI, revealing functional information of the lungs, which were hitherto unattainable. This review article briefly describes the physical background of the technology, and subsequently focuses on its clinical applications.

Finite-difference simulations of 3He diffusion in 3D alveolar ducts: comparison with the "cylinder model".

Time-dependent measurements of 3He diffusion in the lung could provide an accurate method to quantify alveolar length scales and the progression of diseases such as emphysema. However, the apparent diffusion coefficient (ADC) presents a complex problem to model and solve analytically. Here, finite-difference methods were used to simulate diffusion in 3D alveolar ducts.

Comparison between 2D and 3D gradient-echo sequences for MRI of human lung ventilation with hyperpolarized 3He.

Images of hyperpolarized 3He were acquired during breath-hold in four healthy volunteers with the use of an optimized 3D gradient-echo sequence. The images were compared with existing 2D gradient-echo methods. The average SNR from a 13-mm-thick slice in the peripheral lung was 1.

MRI of helium-3 gas in healthy lungs: posture related variations of alveolar size.

Purpose: To probe the variation of alveolar size in healthy lung tissue as a function of posture using diffusion-weighted helium-3 hyperpolarized gas imaging.

Materials And Methods: Measurements of the helium-3 apparent diffusion coefficient (ADC) were made on six healthy subjects. These were used to show the variation of alveolar size between the lowermost dependent regions of the lung compared to the uppermost regions of the lung in four postures: supine, prone, left-lateral decubitus, and right-lateral decubitus.

Diagnosis and management of deep vein thrombosis of the upper extremity: a review.

Deep vein thrombosis of the upper extremity is an increasing clinical problem due to the use of long-term indwelling catheters for chemotherapy or long-term feeding. The clinical diagnosis is difficult to make, and various imaging modalities have been used for this purpose. The use of (interventional) radiological procedures has been advancing in recent years.

Investigating 3He diffusion NMR in the lungs using finite difference simulations and in vivo PGSE experiments.

Finite difference simulations have been used to model (3)He gas diffusion in simulated lung tissue. The technique has the advantage that a wide range of structural models and diffusion-sensitizing gradient waveforms can be investigated, for which analytical methods would otherwise be virtually impossible. Results from simulations and in vivo pulsed-gradient-spin-echo (PGSE) experiments show that the apparent diffusion coefficient (ADC) is a function of diffusion time and gradient strength, and suggests diffusion is locally anisotropic.

MRI for the diagnosis of pulmonary embolism.

Pulmonary embolism (PE) is one of the most frequently encountered clinical emergencies. The diagnosis often involves multiple diagnostic tests, which need to be carried out rapidly to assist in the safe management of the patient. Recent strides in computed tomography (CT) have made big improvements in patient management and efficiency of diagnostic imaging.

Mechanical thrombectomy for early treatment of massive pulmonary embolism.

We report our technique and results of percutaneous mechanical thrombectomy in a consecutive series of eight patients with massive PE. We also discuss the possible role of mechanical PE thrombectomy. Eight consecutive patients with acute massive PE, with or without hemodynamic impairment, were treated with mechanical thrombectomy.

Assessment and compensation of susceptibility artifacts in gradient echo MRI of hyperpolarized 3He gas.

The effects of macroscopic background field gradients upon 2D gradient echo images of inhaled (3)He in the human lung were investigated at 1.5 T. Effective compensation of in-slice signal loss in (3)He gradient echo images was then demonstrated using a multiple acquisition interleaved single gradient echo sequence.

B1AC-MAMBA: B1 array combined with multiple-acquisition micro B0 array parallel magnetic resonance imaging.

The combination of an in-plane B(1) sensitivity encoding (SENSE) technique with a simultaneous multiple-slice B(0) field step technique (multiple-acquisition micro B(0) array (MAMBA)) has produced high scan time reduction factors (R < or = 8). In this study, two slices were acquired simultaneously in combination with x2 and x4 SENSE in-plane encoding using a MAMBA stepped B(0) field coil inside a four-channel phased-array coil system. Experiments were performed on a 1.

Dynamic radial projection MRI of inhaled hyperpolarized 3He gas.

A radial projection sliding-window sequence has been developed for imaging the rapid flow of (3)He gas in human lungs. The short echo time (TE) of the radial sequence lends itself to fast repetition times, and thus allows a rapid update in the image when it is reconstructed with a sliding window. Oversampling in the radial direction combined with angular undersampling can further reduce the time needed to acquire a complete image data set, without significantly compromising spatial resolution.

Deep vein thrombosis of the upper extremity: intra- and interobserver study of digital subtraction venography.

Our objective was to assess the inter-observer and intra-observer agreement in the interpretation of digital subtraction venography (DSV) in patients with suspected deep vein thrombosis of the upper extremity (DVTUE). Prospectively, 62 consecutive DSV studies in 54 patients with clinically suspected DVTUE were included. Hard copies were presented without demographic data or original report.

Assessment of lung ventilation by MR imaging: current status and future perspectives.

The aim of this paper is to review the present status of novel MRI techniques as a new important instrument for functional ventilation imaging. The current status and future perspectives in research and clinical applications are summarized. Morphological lung imaging is based on chest radiography and computed tomography, whereas scintigraphy is used for ventilation imaging.

Prospective study of color duplex ultrasonography compared with contrast venography in patients suspected of having deep venous thrombosis of the upper extremities.

Background: The optimal strategy for diagnosis of deep venous thrombosis (DVT) is less well established for the upper extremities than for the lower extremities. Duplex color ultrasonography can be difficult to perform in the upper extremities because of their anatomy, and contrast venography is often indicated. Moreover, limited data exist on the use of duplex color ultrasonography in this setting.