31P-MR spectroscopy of the human liver - spectral hints on hepatic lymphoma infiltration

Purpose: To evaluate whether phosphorus magnetic resonance spectroscopy (31P-MRS) enables a non-invasive detection of liver involvement in systemic diseases like Hodgkin's lymphoma. Materials and methods: Using a clinical 1.5 Tesla whole-body MR system image-guided localised phosphorus MR spectra from the anatomically defined volumes of interests were measured. A combination of surface coil, adiabatic excitation pulse and modified impage-selected in vivo spectroscopy (ISIS)-sequence was applied. The spectroscopy data were evaluated quantiatively with a time-domain fit programme using non-linear optimisation algorithms to quantify peak areas. After establishment of the examination protocol, 22 healthy volunteers and 13 patients with suspected lymphoma infiltration of the liver were examined. Results: Liver spectra of patients suffering from lymphoma infiltration differed significantly from spectra of persons with normal liver: 1. The peak area ratio of phosphomonoesters (PME) to β-NTP was elevated in all patients with histologically confirmed liver lymphoma. 2. Patients suffering from Hodgkin's disease with specific or unspecific liver infiltration (n=7) could be differentiated from patients without liver involvement. In case of infiltrated liver, the peak area ratio PME to β-NTP was increased, and the pH value was shifted to lower values. Unambiguous differentiation between non-specific (n=3) and specific (n=4) infiltration of the liver was not possible. 3. In patients after cytostatic treatment (n=3), an increase of the peak area ratio of inorganic phosphate to β-NTP was observed. Conclusion: Our preliminary results indicate that 31P-MRS can yield pointers to liver involvement in patients with systemic diseases such as Hodgkin's disease, which may be hardly detected by imaging methods. (orig.)