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 R 1 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 T 1 relaxation rate, R 1 , under normoxic conditions (room air, 21% O 2 ), and the response to various hyperoxic conditions (40%-100% O 2 ) were studied. Lung T 1 in healthy volunteers showed a relatively homogeneous distribution while they breathed room air, and a homogeneous decrease under hyperoxic conditions. Lung T 1 in CF patients showed an inhomogeneous distribution while they breathed room air, and the observed lung Oxygen plays a critical role in the physiology and pathophysiology of the lung. The ability to detect and characterize altered lung oxygen uptake is of great potential value for clinical diagnoses. Thus, in general, functional studies of the human lung address ventilation and gas exchange processes, particularly those of oxygen. The direct use of oxygen as a contrast agent (CA) in an imaging setting would be an interesting means of assessing pulmonary function.Indirect MRI of pulmonary function based on the paramagnetic effects of oxygen physically dissolved in pulmonary blood was demonstrated for the first time by Edelman et al. (1). This pulmonary function test exploits the fact that the amount of dissolved oxygen in the pulmonary blood increases during breathing pure oxygen, resulting in significant signal enhancement in T 1 -weighted lung images. Since the effect of oxygen on the proton spins of blood water, rather than the oxygen molecules themselves, is detected by this method, the diffusion of oxygen from the alveoli to the capillaries of the lungs can only be indirectly measured. However, the diffusion of oxygen is not the only parameter that specifies the observed MR signal in this method, since ventilation-perfusion inequalities also directly affect the observed signal changes. Thus, it has been proposed (2) that different mechanisms, such as ventilation, perfusion, and diffusion, are potentially responsible for the observed signal changes. The major advantage of this oxygen-enhanced approach is its relatively simple experimental setup, since only standard hardware for proton imaging, a ventilatory mask system, and oxygen (which is widely available) as a paramagnetic CA are required. The main current limitations of this approach are that no signal changes are visible at certain T 1 values (i.e., regions without signal changes could mimic pathology, since T 1 is not homogeneous across the entire lung (3,4)), and a quantitative assessment of the pulmonary function is critical because only relative signal changes in T 1 -weighted images are detected. Therefore, quantitative T 1 measurements of oxygen-enhanced MR images have a higher potential for the diagnosis of lung diseas...

In this contribution, a rapid and robust technique for quantitative T(1) mapping of the human lung is presented. Based on a series of Snapshot FLASH tomograms acquired after a single inversion pulse, high quality and quantitative T(1) parameter maps acquired in under five seconds were obtained from six healthy volunteers. The measured T(1) values are in good agreement with previously reported literature values. T(1) maps were also acquired with the volunteers breathing room air or 100% O(2). The T(1) difference between breathing room air and 100% O(2) is statistically significant at P < 0.0001.

Pyomyositis (PM) is an infectious disease of the skeletal muscle with a wide range of symptoms such as pain, fever or swelling, and is predominantly found in the tropics. In recent years PM has increasingly been diagnosed in Europe and in the U.S. Our objective is to describe the ultrasound and MRI features of PM in children. A retrospective analysis of 12 children with PM (2 girls and 10 boys; age range 1-13 years) admitted to our hospital between 1998 and 2002 was carried out. All children had a US exam and 8 children underwent MRI. Children with osteomyelitis and accompanying myositis were excluded from this study. In all patients who had MRI (n=8) the infected muscles were found to have the following features: hyperintensity on the T2-weighted images, diffuse borders and contrast enhancement. In the pelvis (n=4), only one PM could be detected with US, in the other 3 cases only US of the hip joint was performed based on the clinical symptoms. In the extremities (n=8) US always revealed an altered echogenicity of the affected muscles as well as fluid collection in 5 cases. Both US and MRI reveal characteristic changes of the PM. Ultrasound should be the first imaging modality in the extremities. In the pelvis MRI is the imaging modality of choice. The MRI is needed to differentiate pyomyositis from osteomyelitis.

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 1 H 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 T 1 maps based on an inversion recovery Snapshot FLASH technique were acquired from each subject with breath-holds at endexpiration. For comparison, corresponding Gd-DTPA-enhanced 1 H MR perfusion images were also obtained from each CF patient.Results: Quantitative perfusion maps were calculated from the global and selective T 1 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 intrastudy 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 1 H MR mapping of pulmonary perfusion was successfully performed using a rapid lung T 1 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.

Angiomyoma is a benign tumor that arises from soft muscular tissue within the blood vessel wall. This lesion has been found in different organs. The preferential location of these tumors is the lower extremity. We describe the rare case of a hepatic angiomyoma and present the radiologic findings of computed tomography and magnetic resonance imaging.