Multicenter Comparison of Contrast-Enhanced FDG PET/CT and 64-Slice Multi-Detector-Row CT for Initial Staging and Response Evaluation at the End of Treatment in Patients With Lymphoma

Abstract

Objectives: To compare staging correctness between contrast-enhanced FDG PET/ceCT and 64-slice multi-detector-row CT (ceCT64) for initial staging and response evaluation at the end of treatment (EOT) in patients with Hodgkin lymphoma, diffuse large B cell lymphoma (DLBCL), and follicular lymphoma.

Methods: This prospective study compared initial staging and response evaluation at EOT. One hundred eighty-one patients were randomly assigned to either ceCT64 or FDG PET/ceCT. A nuclear medicine physician and a radiologist read FDG PET/ceCT scans independently and achieved post hoc consensus, whereas another independent radiologist interpreted ceCT64 separately. The reference standard included all clinical information, all tests, and follow-up. Ethics committees of the participating centers approved the study, and all participants provided written consent.

Results: Ninety-one patients were randomized to ceCT64 and 90 to FDG PET/ceCT; 72 had Hodgkin lymphoma, 72 had DLBCL, and 37 had follicular lymphoma. There was excellent correlation between the reference standard and initial staging for both FDG PET/ceCT (κ = 0.96) and ceCT64 (κ = 0.84), although evaluation of the response at EOT was excellent only for FDG PET/ceCT (κ = 0.91).

Conclusions: Our study demonstrated satisfactory agreement between FDG PET/ceCT (κ = 0.96) and ceCT64 (κ = 0.84) in initial staging compared with the reference standard (P = 0.16). Response evaluation at EOT with FDG PET/ceCT (κ = 0.91) was superior compared with ceCT64 (κ = 0.307) (P < 0.001).

FIGURE 1

Flowchart for participant selection.

FIGURE 2

A 48-year-old woman diagnosed with DLBCL in whom ceCT64 was false positive in the bone and therefore was overstaged. Initial staging with ceCT64 showed a lymphadenopathy in the right hilum (A) and multiple bone lytic lesions in the pelvis (B). At the EOT, ceCT64 demonstrated complete resolution of the lymphadenopathy in the right hilum (C) and persistent multiple bone lytic lesions in the pelvis with no significant changes (D). Lymphomatous involvement of the bone was suspected based on the ceCT64 images, but the biopsy was negative. The pathology study (E) revealed a fibrous lesion composed of extracellular matrix and fibroblastic cells; no lymphoid cells were present (hematoxylin-eosin stain, original magnification ×200). Immunohistochemistry confirmed the absence of lymphoma cells. After lymphomatous bone disease was later excluded by biopsy, the initial stage IV by ceCT64 due to bone disease was corrected to stage II.

FIGURE 3

A 54-year-old man diagnosed with DLBCL stage IVB in October 2012. Initial staging (A) with ceCT64 demonstrated supradiaphragmatic and infradiaphragmatic lymphadenopathies, splenic and hepatic infiltration, and an abdominal bulky disease (9 cm). At the EOT in June 2013, ceCT64 demonstrated a CR (B). In April 2016, 34 months after the completion of treatment, the patient remains with a CR.

FIGURE 4

A 61-year-old man diagnosed with DLBCL in April 2013. Initial staging with FDG PET/ceCT (A–C) evidenced stage IV supradiaphragmatic and infradiaphragmatic lymphadenopathies, multiples organs with lymphomatous infiltration (gastric, pancreatic, splenic, and renal), and multiple bone lesions, and soft tissue, intratracheal, muscular, and cutaneous infiltration, the largest FDG accumulation being located in the right shoulder with an SUVmax of 23.7. At the EOT in November 2013, FDG PET/ceCT demonstrated a CR (D–F).