title: Beware of the focal uptake at the ischium on the bone scan in prostate cancer.
abstract: BACKGROUND
  The isotope bone scan is routinely used in the management of prostate cancer as the skeleton is the second most common area of metastasis after lymph nodes. A classic site of involvement in the pelvis is the ischium, and the aim of this study was to assess the value of single-photon emission computed tomography/computed tomography (SPECT/CT) imaging in patients with focal ischial uptake on the planar scan.
  
  
  METHODS
  This was a retrospective study of consecutive 150 patients with prostate cancer who were referred for a whole-body bone scan between August 2007 and 2008. Two experienced nuclear medicine consultants along with a musculoskeletal radiologist reviewed the scans.
  
  
  RESULTS
  Sixty-eight patients were diagnosed with widespread metastases and 46 patients showed typical degenerative disease changes on planar whole-body imaging. SPECT/CT imaging was done in 36 patients to clarify the diagnosis in areas of indeterminate uptake noted on planar whole-body imaging. Ten of these 36 patients who had focal increased ischial uptake were included in the study. Only three of these 10 patients were diagnosed as having a metastatic lesion with the presence of an enthesopathy, a common finding.
  
  
  CONCLUSIONS
  Isolated focal uptake in the ischium is a relatively common finding in patients with prostate cancer and there is concern that this, on occasion, could be misinterpreted as metastasis. SPECT/CT imaging has an important role in differentiating a benign from a malignant lesion.
authors.affiliation: Department of Nuclear Medicine, Guy's Hospital, London, UK. drfahim.hassan@gmail.com
authors.forename: Fahim U
authors.initials: FU
authors.lastname: Hassan
authors.forename: Hosahalli Krishnamurthy
authors.initials: HK
authors.lastname: Mohan
authors.forename: Gopinath
authors.initials: G
authors.lastname: Gnanasegaran
authors.forename: Sanjay
authors.initials: S
authors.lastname: Vijayanathan
authors.forename: Ignac
authors.initials: I
authors.lastname: Fogelman
mesh_terms: D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D005189:False Positive Reactions; D006801:Humans; D007512:Ischium / Q000000981:diagnostic imaging* / Q000378:metabolism; D008297:Male; D011471:Prostatic Neoplasms / Q000473:pathology*; D011868:Radioisotopes / Q000493:pharmacokinetics; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013382:Subtraction Technique; D014055:Tomography, Emission-Computed / Q000379:methods*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D011868:Radioisotopes