In vivo 1H NMR spectra of small volumes-of-interest (VOI) were localized in human soleus muscle (8 ml) and compared with volume selective spectra of subcutaneous fat tissue and femoral yellow bone marrow (2 ml). All examinations were performed by the double spin echo (PRESS) localization technique. To provide comparability, spectra of different tissues were recorded using identical sequence timing. Clearly improved resolution of the lipid signals of muscle tissue was obtained using long echo times TE > 200 ms. The spectra of muscle tissue exhibit lipid signals that stem from two compartments with a difference of their resonance frequencies of about 0.2 ppm (Larmor frequency difference 12-13 Hz at 1.5 T). The existence of two fatty acid compartments is supported by measurements of the relaxation times and line shape analysis. Both compartments contain fatty acids or triglycerides with similar composition. Probably one compartment corresponds to fat cells within muscle tissue, the other compartment with lower Larmor frequency is located within muscle cells.

Volume-selective 1H magnetic resonance spectra of small volume elements of (13 mm)3 positioned in lumbar vertebral bodies have been investigated in 15 healthy persons of different ages and sexes and in 11 patients with leukemia using double spin-echo sequences. Signal intensities and positions of the spectral lines have been evaluated. Interindividual spectra of VOI located in the center of vertebral bodies, intraindividual spectra of central VOI in different vertebral bodies, and spectra of different localizations within the same vertebral body have been compared as well as spectra before and partly after cytostatic treatment in leukemia patients. Unexpected phenomena of the signal shapes have been found. The water signal distributions in healthy persons compared to patients after bone marrow transplantation show significant differences. The success of the cytostatic treatment in cases of leukemia is accompanied by an increase in the intensity of the lipid signals and a decrease in the water signals.

Citrate is a secretory product of the normal prostate, a lack of citrate in prostate tissue is expected to be pathognomonic for adenocarcinoma. In the present study proton AB-signal characteristics of citrate at low field strength of 1.5 T were investigated by volume selective spectroscopic and theoretical methods. The nonappearance of fast phase modulation of the J-coupled system at low field strength in vivo is verified by measurements of sodium citrate solution. In vivo localized spectroscopy of small volume elements of (2 cm)3 with the double spin-echo method within the prostatic gland provides citrate signal reception even using a Helmholtz coil with 170-mm diameter. Volume selective proton spectra with different echo times are presented which are comparable to spectra acquired by former authors with endorectal coils.

Red bone marrow of healthy persons has considerable contents of water and lipids. The cellularity and the corresponding fat-water ratio within the marrow show clear changes in hematological diseases. Magnetic resonance (MR) methods use the signals of the protons of water and lipids. This paper gives a comparison between different standard MR techniques and recently developed fat- and water-selective imaging methods, addressing their sensitivity to bone marrow changes in leukemia. Additionally, 1H results of spectroscopic methods are presented. The results and conclusions are based on the examination of 26 healthy volunteers and 106 patients with general or focal bone marrow alterations. Standard T1-weighted images did not distinguish bone marrow of young healthy volunteers with relatively high cellularity from acute leukemia. Using fat- and water-selective methods, patients with untreated leukemia showed only water proton signals and no lipid signals from red bone marrow of vertebral bodies and the pelvis. This phenomenon was never observed in healthy volunteers. Following chemotherapy, lipid and water contents normalize in successfully treated patients. Nonresponders did not show significant changes of the fat-water ratio after up to 3 weeks of therapy. Phase contrast imaging provides information about the difference between fat and water fractions within the bone marrow, but quantitative determination of the absolute fat and water fractions requires acquisition of several images and suffers from the susceptibility effects in trabecular bone marrow. The fat-water ratio and additional qualities of water and lipid protons (relaxation times) can be evaluated by volume-selective MR spectroscopy. Typical results of spectra from small-volume elements in hypercellular vertebral bone marrow of leukemic patients before cytotoxic treatment and of normocellular or hypocellular marrow after therapy are demonstrated.

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