Detection of Richter's Transformation of Chronic Lymphocytic Leukemia by PET/CT

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BlankJournal of Nuclear Medicine Vol. 47 No. 8 1267-1273

© 2006 by Society of Nuclear Medicine

Detection of Richter's Transformation of Chronic Lymphocytic Leukemia by PET/CT

F. Bruzzi1, Homer Macapinlac1, Apostolia M. Tsimberidou2, Mylene T.

Truong1, J. Keating2, Edith M. Marom1 and Reginald F. Munden1

1 Division of Diagnostic Imaging, M.D. Cancer Center, Houston, Texas;

and 2 Department of Leukemia, M.D. Cancer Center, Houston, Texas

Correspondence: For correspondence or reprints contact: F. Bruzzi, Division

of Diagnostic Imaging, M.D. Cancer Center, 1515 Holcombe Blvd., Unit

57, Houston, TX 77030-4009. E-mail: jbruzzi@...

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. Conclusion: 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.

Key Words: chronic lymphocytic leukemia • Richter's transformation • lymphoma •

PET • PET/CT