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We have recently demonstrated a non-invasive technique to visualize pulmonary ventilation in humans with inhalation of molecular oxygen as a paramagnetic contrast agent. In the current study, T1 shortening of lung tissue by inhalation of oxygen was observed (P<0.001). The T1 values of lung tissue were also correlated with arterial blood oxygen pressure (PaO(2)) in a pig, resulting in excellent correlation (r(2)=0.997). Dynamic wash-in and wash-out MR ventilation images as well as dynamic wash-in wash-out signal intensity versus time curves were obtained. The mean wash-in decay constants were 26.8+/-10.5 s in the right lung, and 26.3+/-9.5 s in the left lung. The mean wash-out decay constants were 23.3+/-11.3 s in the right lung, and 20.8+/-10.5 s in the left lung. Dynamic assessment of pulmonary ventilation is feasible using oxygen-enhanced MR imaging, which could provide dynamic MR ventilation-perfusion imaging in combination with recently developed MR perfusion imaging technique, and thus a robust tool for the study of pulmonary physiology and pathophysiology.

Biochemical and histologic data have validated the technique of delayed gadolinium-enhanced MRI, in which the T(1) values of cartilage after penetration of Gd(DTPA)2-allow assessment of the glycosaminoglycan (GAG) component of articular cartilage. This work describes the factors that have been found to be important for the practical implementation of the technique: 1) Exercise immediately after intravenous contrast administration was necessary for effective penetration of the contrast into the articular cartilage; 2) double-dose contrast was better than single-dose; 3) after contrast administration, a time window of 30-90 min for the hip, and 2-3 hr for all compartments of the knee proved to be appropriate for assessing articular cartilage; and 4) in some cases of hypointensities in the subchondral patellar bone, decreased penetration of the contrast agent into cartilage from bone was found. With the protocol described, ROIs on T(1) images were reproducible within 15% on two separate imaging sessions, and initial clinical studies demonstrated the possible applications of the technique. Magn Reson Med 45:36-41, 2001., (Copyright 2001 Wiley-Liss, Inc.)

Magnetic resonance imaging is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

Magnetic resonance is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

The objective of this study was to measure T2* values of the normal human lung in vivo during breathhold using a rapid gradient-echo sequence with ultra-short echo times (TE). A sagittal slice of the right lung was imaged in six volunteers with various TE ranging from 0.5 ms to 5 ms using a clinical 1.5 Tesla MR scanner. T2* values were calculated in a region of interest in the dependent and non-dependent lung. In the dependent lung, T2* values of 1.1 ms+/-0.15 ms were measured, and in the non-dependent lung, 0.86 ms+/-0.11 (p < 0.01). T2* measurements of the normal human lung during breathhold are feasible with a clinical MR unit. The short T2* values require the use of very short TE times (< 2.5 ms) in gradient-echo sequences to obtain adequate signal intensity from lung tissue.

Lung ventilation imaging using inhaled oxygen as a contrast medium was performed using both a 0.2 and a 1.5 T clinical magnetic resonance (MR) scanner in eight volunteers. Signal-to-noise-ratios (SNRs) of the ventilation images as well as T1 values of the lung acquired with inhalation of 100% oxygen and room air were calculated. The SNR was 9.7 +/- 3.0 on the 0.2 T MR system and 69.5 +/- 28.8 on the 1.5 T system (P < 0.001). The mean T1 value on the 0.2 T MR system with subjects breathing room air was 632 +/- 54 msec; with 100% oxygen, it was 586 +/- 41 msec (P < 0.01). At 1.5 T, the mean values were 904 +/- 99 msec and 790 +/- 114 msec, respectively (P < 0.0001). We conclude that MR oxygen-enhanced ventilation imaging of the lung is feasible with an open configured 0.2 T MR system.

Imaging of lung perfusion using contrast-enhanced dynamic magnetic resonance (MR) was performed in both the supine and prone positions in six volunteers. Regions of interest (ROIs) were chosen in the dependent and non-dependent portions of the right lung. The percentage increase in signal intensity (SI) and the mean slope were calculated. In the supine position, the dorsal ROI had a greater increase in SI (236.0% vs. 156.9%, P < 0.05) and a faster rise in the slope of enhancement (55.1%/sec vs. 30.1%/sec, P < 0.05) than the ventral ROI. After changing to the prone position, higher peak enhancement (234.3% vs. 177.4%, P < 0.05) and faster slopes (59.6%/sec vs. 35.3%/sec, P < 0.05) shifted to the anterior ROI. We conclude that dynamic contrast-enhanced MR imaging is sensitive to demonstrate gravitationally dependent differences in lung perfusion.

This article reviews fast magnetic resonance (MR) techniques currently used for body imaging. Improvements in gradient performance have made very short repetition and echo times on clinical scanners feasible, thus enabling subsecond image acquisition. The article provides a fundamental overview of the technical aspects from the concept of k-space and k-space segmentation technique, fast MR imaging techniques including fast spin echo, fast gradient echo with or without magnetization preparation to echo planar and hybrid techniques. The article also addresses the use of different fat suppression techniques in MR imaging of the body and improvements in coil technology to obtain faster images and higher signal-to-noise.

The impact of fast MR techniques developed for MR imaging of the lung will soon be recognized as equivalent to the high-resolution technique in chest CT imaging. In this article, the difficulties in MR imaging posed by lung morphology and its physiological motion are briefly introduced. Then, fast MR imaging techniques to overcome the problems of lung imaging and recent applications of the fast MR techniques including pulmonary perfusion and ventilation imaging are discussed. Fast MR imaging opens a new exciting window to multi-functional MR imaging of the lung. We believe that fast MR functional imaging will play an important role in the assessment of pulmonary function and disease process.

Objective: To evaluate the utility of a half-Fourier single-shot turbo spin-echo sequence (HASTE) at depicting lung parenchyma and lung pathology., Methods and Patients: A HASTE sequence was applied to five normal volunteers and 20 patients with various pulmonary disorders to depict the lung parenchyma. Images were acquired with ECG-triggering and breath-holding. In three volunteers, signal intensity measurements from lung parenchyma were performed using four sequences: (a) HASTE; (b) conventional spin echo; (c) fast spin echo; and (d) gradient echo. T2 maps were produced using the HASTE acquisition., Results: Minimal respiratory or cardiac motion artifacts were observed. The signal-to-noise ratios from lung parenchyma were 27.8 +/- 5.4, 22.0 +/- 3.0, 15.3 +/- 0.9, and 6.0 +/- 1.9 for HASTE, spin-echo, fast spin-echo, and gradient echo sequences, respectively. The scan time for HASTE was 302 ms for each slice. The T2 values in the right lung and the left lung were 61.2 +/- 4.1 and 79.1 +/- 8.9 ms in systole and 92.6 +/- 5.8 and 97.5 +/- 12.2 ms in diastole, respectively (P < 0.05 diastole versus systole). The HASTE sequence demonstrated clearly various pulmonary disorders, including lung cancer, hilar lymphadenopathy, metastatic pulmonary nodules as small as 3 mm, pulmonary hemorrhage, pulmonary edema and bronchial wall thickening in bronchiectasis., Conclusion: Our preliminary results indicate that the HASTE sequence provides a practical means for breath-hold MR imaging of lung parenchyma.

A patient with AL (amyloid light chain) amyloidosis was investigated in liver and brain by localized magnetic resonance spectroscopy. Liver spectra of the patient were characterized by small line widths, a striking increase of trimethylammonium compounds, and the presence of a further resonance at 3.8 ppm. None of the healthy control subjects showed trimethylammonium levels of comparable intensity. In the brain, the intensities of amino acids was relatively increased in white matter, whereas the concentration of choline, creatine, and N-acetyl-aspartate were reduced.

We describe three cases of acute disseminated encephalomyelitis (an immune-mediated inflammatory demyelinating disease of the central nervous system) and their histology, showing different radiological features. One appearance is a few ring-shaped enhancing lesions, which are found predominantly in the supratentorial white matter, the other is solid disseminated lesions.

MRA (magnetic resonance angiography) is besides duplex sonography at present the only noninvasive method for vascular visualisation. The technical fundamentals and our initial experiences with this new technique of angiography in the visualisation of the basilar artery are presented in the following article.

Background and aims: The diagnostic yield of capsule endoscopy (CE) compared with magnetic resonance imaging (MRI) in small bowel Crohn's disease is not well established. We prospectively investigated CE, MRI, and double contrast Huoroscopy in patients with suspected small bowel Crohn's disease. Methods: Fifty two consecutive patients (39 females, 13 males) were investigated by MRI, fluoroscopy and- if bowel obstruction could be excluded-by CE. In 25, Crohn's disease was newly suspected while the diagnosis of Crohn's disease (non-small bowel) had been previously established in 27. Results: Small bowel Crohn's disease was diagnosed in 41 of 52 patients (79%). CE was not accomplished in 14 patients due to bowel strictures. Of the remaining 27 patients, CE, MRI, and fluoroscopy detected small bowel Crohn's disease in 25 (93%), 21(78%), and 7 (of 21; 33%) cases, respectively. CE was the only diagnostic tool in four patients. CE was slightly more sensitive than MRI (12 v 10 of 13 in suspected Crohn's disease and 13 v 11 of 14 in established Crohn's disease). MRI detected inflammatory conglomerates and enteric fistulae in three and two cases, respectively. Conclusion: CE and MRI are complementary methods for diagnosing small bowel Crohn's disease. CE is capable of detecting limited mucosal lesions that may be missed by MRI, but awareness of bowel obstruction is mandatory. In contrast, MRI is helpful in identifying transmural Crohn's disease and extraluminal lesions, and may exclude strictures. [ABSTRACT FROM AUTHOR]