In vivo 1H MR spectroscopy of thyroid carcinoma.

To determine if proton magnetic resonance spectroscopy (1H MRS) of thyroid carcinoma is feasible and to determine if 1H MRS spectra of malignant tumors differ from that of normal thyroid tissue. We performed 1H MRS at 1.5 T at echo-times (TE) 136 and 272 ms to examine eight patients with thyroid cancer (primary tumour or nodal metastasis) larger than 1 cm3 in size and five volunteers with normal thyroids. Spectra acquired from six primary tumors (three anaplastic carcinomas, two papillary carcinomas and one follicular carcinoma) and two nodes (two papillary carcinoma metastases) were analyzed in the time-domain using a non-linear least squares fitting algorithm with incorporation of prior knowledge. Choline (3.2 ppm) was identified in all solid carcinomas with a mean choline/creatine of 4.3 at TE 136 ms and 5.4 at TE 272 ms. Ratios for malignant tumors at TE 136 ms ranged from 1.6 in well differentiated follicular carcinoma to 9.4 in anaplastic carcinoma. No choline was detected in normal thyroid tissues. Our results showed that 1H MRS is a feasible technique for the evaluation of malignant thyroid tumors larger than 1 cm3 and that proton spectra of malignant tumors differ from that of normal thyroid tissue.

A study of bone marrow and subcutaneous fatty acid composition in subjects of varying bone mineral density.

Osteoporosis is associated with an increase in marrow fat. Fats, particularly polyunsaturated fats, either in co-cultures or diet, have been shown to significantly influence bone remodeling. Whether the increase in marrow fat seen in osteoporosis is also associated with a change in fatty acid composition is not known. This study was undertaken to investigate the fatty acid composition in subjects of varying bone mineral density (BMD). Samples of marrow fat and subcutaneous fat from 126 subjects (98 females, 34 males, mean age 69.7+/-10.5 years) undergoing orthopedic surgery were analyzed for fatty acid composition by gas chromatography. These results were correlated with BMD assessed by DXA. A total of 22 fatty acids were identified in marrow and subcutaneous fat. Significant differences in fatty acid composition existed between marrow and subcutaneous fat as well as between marrow fat samples obtained from the proximal femur and proximal tibia. Other than cis-7-hexadecenoic acid [C16:1 (n=9)] and docosanoic acid [C22:0], no difference in marrow fatty acid composition was evident between subject groups of varying BMD (normal, low bone mass, and osteoporosis). In conclusion, there exists a wide range of individual fatty acids in marrow fat. Marrow fatty acid composition differs from that of subcutaneous fat and varies between predominantly erythropoetic and fatty marrow sites. Other than cis-7-hexadecenoic acid [C16:1 (n=9)] and docosanoic acid [C22:0], no difference in marrow fatty acid composition was evident between subjects of varying BMD.