Leakage of metabolites from tissue biopsies can result in large errors in quantitation by MRS

The leakage of metabolites from frozen and thawed tissue biopsies was measured semi-quantitatively by high-field (8.5 T) proton MRS. Human prostate and rat brain tissue specimens, frozen within 1 min of collection, lost significant and variable amounts of diagnostic metabolites immediately upon thawing. For prostate tissue 30–50% of initial total choline compounds, total creatines and citrate were detected in the collection buffer immediately after thawing. The widely used protocol for MR assessment of tissue biopsies, which involves washing of thawed tissue samples in fresh buffer, results in loss of large and unpredictable amounts of possibly diagnostic metabolites prior to MRS. This reduces the reproducibility of MR analysis of tissue biopsies and compromises the reliable identification of MR spectral patterns diagnostic of tissue pathology. The problem can be avoided by minimizing the volume of storage buffer, omitting tissue washing and performing MRS measurements on the tissue immersed in the original storage buffer

Correlation of histopathology with magnetic resonance spectroscopy of human biopsies

NRC publication: Ye

In vivo spectroscopy and imaging of the ovary in vivo at 3 tesla and spectroscopy on biopsy at 8.5 tesla

In vivo spectroscopy and imaging of the ovary at 3T can provide diagnostic information preoperatively on patients with ovarian masses. Here is the first report of a case where the in vivo MRI and MRS at 3T were undertaken on a patient with an ovarian mass distinguishing the malignant from the cystic component. Spectroscopy on biopsies obtained intraoperatively and recorded at 8.5T provided a diagnosis of poorly differentiated malignant tumor. The MR studies were undertaken blind and the diagnosis subsequently confirmed histologically

In vivo and ex vivo proton MR spectroscopy of primary and secondary melanoma

In vivo magnetic resonance (MR) spectroscopy at 1.5T was performed on a large polypoid cutaneous melanoma, and two enlarged lymph nodes containing metastatic melanoma, from three patients. Spectra were acquired in vivo from voxels wholly within the primary tumour or secondary lymph node and were thus uncontaminated by signals from adjacent tissue. Tissue biopsies taken after resection of primary tumours and secondary lymph nodes were examined by 8.5T magnetic resonance spectroscopy (MRS) and the results compared with the in vivo spectra, and with spectra from normal skin and a benign skin lesion. There was good agreement between the dominant features of 1.5T spectra acquired in vivo and 8.5T spectra acquired from resected tissue. However, less intense resonances observed at 8.5T in malignant biopsy tissue were not consistently observed at 1.5T in vivo. In vivo spectra from primary and metastatic melanoma showed high levels of choline metabolites. An intense lactate resonance was also present in the in vivo spectrum of primary melanoma. All 8.5T spectra of biopsies from primary and secondary melanoma showed high levels of choline metabolites and lactate, and additional resonances consistent with elevated levels of taurine, alanine, lysine, and glutamate/glutamine relative to normal and benign tissue. Elevated levels of choline, lactate, taurine, and amino acids appear to be clinically useful markers for identifying the pathology of primary and metastatic melanoma