title: Detection of Richter's transformation of chronic lymphocytic leukemia by PET/CT.
abstract: Our objective was to evaluate the accuracy of PET/CT for the diagnosis of Richter's transformation of chronic lymphocytic leukemia (CLL) to diffuse large cell lymphoma.
  
  
  METHODS
  A retrospective study was performed of 37 patients with CLL who underwent 18F-FDG PET/CT at our institution between March 2003 and July 2005. All PET/CT scans were reviewed in consensus by 2 diagnostic radiologists. Sites of abnormal 18F-FDG uptake with a maximum standardized uptake value (SUVmax) of greater than 5 were considered highly suggestive of Richter's transformation. The PET/CT findings were correlated with histologic findings from bone marrow or lymph node biopsy performed within 6 wk of PET/CT and with clinical follow-up.
  
  
  RESULTS
  The 37 patients (26 men and 11 women; mean age, 61 y, range, 40-82 y) underwent 57 PET/CT scans. In 10 (91%) of 11 patients with Richter's transformation, PET/CT detected sites of abnormal 18F-FDG uptake having an SUVmax of greater than 5. Richter's transformation was missed in 1 patient who had only low-grade 18F-FDG uptake (SUVmax < 5). Nine patients had false-positive PET/CT findings; in 3 of these patients, alternative malignancies were diagnosed (Hodgkin's disease; metastatic neuroendocrine carcinoma; non-small cell lung cancer). In all remaining patients, PET/CT correctly excluded Richter's transformation. For the specific diagnosis of Richter's transformation of CLL to diffuse large B-cell lymphoma, PET/CT had overall sensitivity, specificity, and positive and negative predictive values of 91%, 80%, and 53% and 97%, respectively.
  
  
  CONCLUSIONS
  PET/CT can detect Richter's transformation of CLL to diffuse large B-cell lymphoma with a high sensitivity and a high negative predictive value.
authors.affiliation: Division of Diagnostic Imaging, M.D. Anderson Cancer Center, Houston, Texas 77030-4009, USA. jbruzzi@mdanderson.org
authors.forename: John F
authors.initials: JF
authors.lastname: Bruzzi
authors.forename: Homer
authors.initials: H
authors.lastname: Macapinlac
authors.forename: Apostolia M
authors.initials: AM
authors.lastname: Tsimberidou
authors.forename: Mylene T
authors.initials: MT
authors.lastname: Truong
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Keating
authors.forename: Edith M
authors.initials: EM
authors.lastname: Marom
authors.forename: Reginald F
authors.initials: RF
authors.lastname: Munden
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic; D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D049268:Positron-Emission Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*