Abstract
Purpose: :
To assess hybrid whole-body 18fluoro-deoxyglucose Positron Emission Tomography/Computed tomography (PET-CT) imaging for orbital/adnexal mucosa-associated lymphoid tissue (MALT) type marginal zone B-cell lymphoma at presentation and after radiotherapy.
Methods: :
A retrospective chart review of 19 patients with biopsy-proven orbital/adnexal MALT lymphoma who underwent whole-body PET-CT was performed. There were 13 females, 6 males, with a median age of 50. Three affected both eyes. Whole-body PET-CT of all patients were reviewed by a single nuclear medicine specialist blinded to the laterality of the presenting orbital lesion. All patients underwent radiotherapy with a mean 30.6 Gy in seventeen 180cGy fractions. Nine patients had PET-CT after radiotherapy.
Results: :
Standard uptake values (SUV) for primary lesions at presentation were 1.6-7.5 (mean/median, 3.3/2.7). With threshold SUV 3.0, sensitivity of PET-CT for primary lesions was 45%; specificity, 63%; positive predictive value (PPV), 63%; negative predictive value (NPV), 45%. Maximum SUV for systemic involvement ranged from 1.2-17.5 (mean/median, 2.8/4.2). Although 5 of 19 (26%) patients had apparent radiologic systemic uptake, only 2(11%) had actual metastases confirmed by biopsy, including 1 regional treatment failure. With threshold SUV 3.0, sensitivity of PET-CT for systemic involvement was 100%; specificity, 82%; PPV, 40%; and NPV, 100%. Laterality of the lesion was accurately predicted in 11 out of 16 (69%) unilateral cases, with differences between the involved and uninvolved orbit of -0.3 to 2.8 SUV (mean/median, 0.5/0.2). In 3 bilateral cases, only 1 primary lesion had SUV ≥ 3. However, using threshold SUV ≥2, all bilateral lesions were detected. In the 9 patients with post-radiotherapy PET-CT after 3-22 months (mean/median 9.2/6 months), there was decreased SUV in primary lesions in 6 of 10 eyes (mean/median difference SUV 0/0.3, range -2.6 to 1.6), and decreased systemic uptake in 11 of 13 areas (mean/median difference SUV 2.6/0.9, range 0-15.7).
Conclusions: :
Local and systemic orbital/adnexal MALT lymphoma can be imaged with PET-CT. PET-CT was highly sensitive for detecting systemic spread of disease. A higher incidence of metastasis (2 out of 19 cases) was found in this cohort as compared to the literature. The efficacy of radiation therapy was demonstrated by decreased tumor-related metabolic activity (SUV).
Keywords: oncology • imaging/image analysis: clinical • radiation therapy