title: Differentiation between healthy thyroid remnants and tumor tissue after radioiodine therapy in patients with differentiated thyroid carcinoma using in vitro phosphorus-31 magnetic resonance spectroscopy.
abstract: BACKGROUND
  The growth and spread of many tumors are triggered by changes in cell membrane metabolism, which can lead to systemic alterations in levels of phospholipids. We sought to determine whether plasma levels of several phospholipids could differentiate between healthy remnants of thyroid tissue and residual tumor tissue or metastases in patients with thyroid carcinoma.
  
  
  METHODS
  We measured plasma phospholipid levels by phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in blood samples from 30 patients with thyroid cancer who had been rendered hypothyroid in preparation for diagnostic or therapeutic administration of iodine-131. All patients had undergone total thyroidectomy. Iodine-131 whole-body scintigraphy and measurements of thyroglobulin values during up to 3 years of follow-up were used to distinguish patients in remission from those with only healthy thyroid remnants and those with tumor tissue or metastases.
  
  
  RESULTS
  Mean (+/- SD) levels of sphingomyelin (0.33 +/- 0.06 mmol/L vs. 0.46 +/- 0.03 mmol/L, P <0.0001) and phosphatidylcholine (1.34 +/- 0.19 mmol/L vs. 2.15 +/- 0.33 mmol/L, P <0.0001) were significantly lower in patients with metastatic thyroid cancer (n = 8) than in patients (n = 12) who were in remission. Patients with only remnants of thyroid tissue (n = 10) also had significantly lower phospholipid levels than did patients in remission, but significantly greater levels that did patients with tumor tissue or metastases.
  
  
  CONCLUSIONS
  These preliminary results suggest that 31P-MRS may be useful in helping to differentiate the presence of tumor tissue, remnants of thyroid tissue not requiring further treatment, and remission in patients with thyroid cancer.
authors.affiliation: Department of Nuclear Medicine, University of Cologne, Köln, Germany.
authors.forename: Detlef
authors.initials: D
authors.lastname: Moka
authors.forename: Markus
authors.initials: M
authors.lastname: Dietlein
authors.forename: Klaus
authors.initials: K
authors.lastname: Raffelt
authors.forename: Josef
authors.initials: J
authors.lastname: Hahn
authors.forename: Harald
authors.initials: H
authors.lastname: Schicha
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D010743:Phospholipids / Q000097:blood*; D010761:Phosphorus Radioisotopes; D011877:Radionuclide Imaging; D013961:Thyroid Gland / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D007457:Iodine Radioisotopes; D010743:Phospholipids; D010761:Phosphorus Radioisotopes