Potential Value of Apparent Diffusion Coefficient (ADC) in First-Line Treatment of Retinoblastoma

Background and Purposes: Assess the correlation between Apparent Diffusion Coefficient (ADC) values and prognostic parameters in retinoblastoma, including a possible contribution to prediction of response to intra-arterial chemotherapy (IAC). Materials and Methods: Conventional MR images and ADC-maps in 38 retinoblastoma patients (23 males, 15 females, mean age 26.8 months, 4 group B, 2 group C, 15 group D, and 17 group E; ABC classification) were assessed. Echo Planar Imaging-Diffusion Weighted Imaging was performed before treatment with two B values (b 0 and 1000 s/mm2), slice thickness 2.6 mm. Mean ADCvalues in patients who underwent enucleation and those not-enucleated who underwent intra-arterial chemotherapy as first-line treatment were compared. ADC-values were correlated with tumor size and differentiation. Results: Larger tumors showed lower ADC values. The difference in ADC-values between enucleated (mean= 880.7 x 10 ̄6 mm2/sec) and not enucleated patients (mean = 1026 x 10 ̄6 mm2/sec) was statistically significant (p = 0.002). A cut-off of 957.6 x 10 ̄6 mm2/sec may be suggested as a supplementary factor in discriminating tumors with different eye-survival prognosis (enucleation vs conservative treatment) (sensitivity 78%, specificity 66%, and accuracy 71%). Conclusions: ADC may be taken in account when making a decision about the treatment of retinoblastoma. Although ADC alone is limited, and likely will be more useful clinically as a component in a multiparametric model. Synopsis: ADC may be an adjunctive parameter to determine the best first-line treatment for a patient with retinoblastoma.