[Nuclear spin tomography in fully implanted catheter systems].
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Catheters, Indwelling↗
Biomedical subjects
J Gieseke
Publications and source records attributed to J Gieseke.
[Diagnosis of lymphomas on the MR tomogram].
MR tomography provides images equal to, or superior to, CT of lymph node involvement in the thorax or abdomen. It may be possible to achieve tissue characterisation by means of T1 and T2 images. Chronic inflammatory diseases causing lymph node enlargement, such as sarcoidosis, show characteristic T1 intervals (about 650 msecs), whereas lymphomas show intervals of 900 msecs. Enlarged lymph nodes of low malignancy show lower T2 values (78 to 94 msecs), highly malignant show higher T2 values (83 to 145 msecs). Already we believe MR to be the method of choice in evaluating lymphoma and sarcoidosis.
Abdomen↗
MR angiography of congenital heart disease: value of segmented two-dimensional inflow technique and maximum-intensity-projection display.
Magnetic resonance (MR) angiography of the cardiovascular system was evaluated in 41 patients with congenital heart disease by using a two-dimensional (2D) inflow technique based on a magnetization-prepared gradient-echo pulse sequence with segmented k-space data acquisition and electrocardiographic gating at 0.5 T. Inversion and saturation prepulses were used to suppress stationary tissue and enhance intravascular signal. Presaturation slabs were applied where certain vascular structures had to be suppressed. Sequence parameters were optimized by evaluating signal intensity and contrast characteristics for various flip angles and inversion and saturation delay times. The heart and intrathoracic vasculature were encompassed with 40-50 overlapping sections. Both 2D angiograms and maximum-intensity-projection images were evaluated. Combining data sets acquired in the sagittal and transverse orientations provided the most satisfactory information about the pulmonary arteries. The highest signal-to-noise ratios were obtained with a flip angle of 65 degrees and short prepulse delay times. Two-dimensional MR angiography can provide useful diagnostic information but requires a thorough understanding of in-plane and hemodynamically induced signal intensity changes.
Aorta↗
Determination of 1H relaxation times of water in human bone marrow by fat-suppressed turbo spin echo in comparison to MR spectroscopic methods.
Relaxation times of water were measured in human vertebral bodies by a fat-suppressed dual-echo turbo spin echo/turbo inversion recovery MRI sequence. Comparison was made with T1 and T2 values obtained by localized 1H-MR spectroscopy. The accuracy of the results and the diagnostic potential of the fast quantitative MRI technique were evaluated in 20 volunteers, 11 patients with osteoporosis, 6 patients with lymphoma, and 6 patients with bone marrow metastasis. No significant alterations of T1 and T2 relaxation times of water and fat were found in osteoporosis. With both methods, an increase in the T1 values of the water resonance by 16% was observed in lymphomas, which was highly significant (P < .001) in the MRS measurements, and an elevation by the same amount was obtained by the MRI sequence for the metastases (P = .040). A strong reduction of fat fraction was quantified by MRS in the tumorous cases. T2 of the water resonance increased by more than 30% (P < .003) in metastases. Water T2 values obtained by the MRI sequence showed systematic deviations from the MRS results, especially at short echo spacings.
Adipose Tissue↗
Prospective comparison of fast SE and GRASE sequences and echo planar imaging with conventional SE sequences in the detection of focal liver lesions at 1.0 T.
PURPOSE: Our goal was to investigate the value of T2-weighted fast SE (FSE) sequences, FSE sequences with shortened echo spacing (UFSE), combined gradient and spin echo sequences (GRASE), and segmented T1-weighted echo planar imaging (EPI) in comparison with conventional SE sequences in the detection of focal liver lesions. METHOD: Thirty-five patients with malignant focal liver lesions underwent MRI at 1.0 T. RESULTS: All fast T2-weighted imaging techniques (FSE, UFSE, GRASE) showed fewer artifacts and overall better image quality than the conventional SE sequence. Quantitative analysis demonstrated that UFSE imaging had the highest tumor/liver contrast/noise ratio (C/N) (13.9 +/- 5.5) followed by FSE (12.7 +/- 4.5), T2 SE (10.9 +/- 4.2), and GRASE (10.0 +/- 4.8) sequences. The differences in C/N between the UFSE and T2 SE sequences was statistically significant (p < 0.05). C/N was significantly higher (p < 0.01) for the T1 SE (-7.4 +/- 3.8) than for the EPI sequence (-0.5 +/- 5.6). CONCLUSION: FSE sequences with shortened echo spacing are valuable for liver imaging at 1.0 T. In comparison with the T2 SE sequence, they yielded better image quality and comparable tumor/liver C/N.
Adult↗