Abstract
BackgroundHigh‐risk neuroblastoma (HR‐NB) has a variable response to preoperative chemotherapy. It is not possible to differentiate viable vs. nonviable residual tumor before surgery.PurposeTo explore the association between apparent diffusion coefficient (ADC) values from diffusion‐weighted magnetic resonance imaging (DW‐MRI), 123I‐meta‐iodobenzyl‐guanidine (123I‐mIBG) uptake, and histology before and after chemotherapy.Study TypeRetrospective.SubjectsForty patients with HR‐NB.Field Strength/Sequence1.5T axial DW‐MRI (b = 0,1000 s/mm2) and T2‐weighted sequences. 123I‐mIBG scintigraphy planar imaging (all patients), with additional 123I‐mIBG single‐photon emission computed tomography / computerized tomography (SPECT/CT) imaging (15 patients).AssessmentADC maps and 123I‐mIBG SPECT/CT images were coregistered to the T2‐weighted images. 123I‐mIBG uptake was normalized with a tumor‐to‐liver count ratio (TLCR). Regions of interest (ROIs) for primary tumor volume and different intratumor subregions were drawn. The lower quartile ADC value (ADC25prc) was used over the entire tumor volume and the overall level of 123I‐mIBG uptake was graded into avidity groups.Statistical TestsAnalysis of variance (ANOVA) and linear regression were used to compare ADC and MIBG values before and after treatment. Threshold values to classify tumors as viable/necrotic were obtained using ROC analysis of ADC and TLCR values.ResultsNo significant difference in whole‐tumor ADC25prc values were found between different 123I‐mIBG avidity groups pre‐ (P = 0.31) or postchemotherapy (P = 0.35). In the “intratumor” analysis, 5/15 patients (prechemotherapy) and 0/14 patients (postchemotherapy) showed a significant correlation between ADC and TLCR values (P < 0.05). Increased tumor shrinkage was associated with lower pretreatment tumor ADC25prc values (P < 0.001); no association was found with pretreatment 123I‐mIBG avidity (P = 0.17). Completely nonviable tumors had significantly lower postchemotherapy ADC25prc values than tumors with >10% viable tumor (P < 0.05). Both pre‐ and posttreatment TLCR values were significantly higher in patients with >50% viable tumor than those with 10–50% viable tumor (P < 0.05).Data Conclusion 123I‐mIBG avidity and ADC values are complementary noninvasive biomarkers of therapeutic response in HR‐NB.Level of Evidence4.Technical Efficacy Stage3.
Highlights
High-risk neuroblastoma (HR-NB) has a variable response to preoperative chemotherapy
The intratumor linear models revealed a significant negative correlation between apparent diffusion coefficient (ADC) and to-liver count ratio (TLCR) in only 5/15 tumors before chemotherapy (P < 0.05 after multiple comparison correction, Table 2), with lower ADC values being associated with higher TLCR values
No significant correlation was found between median ADC and TLCR values in the most avid part of each primary tumor, at both the prechemotherapy (R2 = 0.13, P = 0.18) and postchemotherapy (R2 = 0.0008, P = 0.92) timepoints (Fig. 3)
Summary
High-risk neuroblastoma (HR-NB) has a variable response to preoperative chemotherapy. The lower quartile ADC value (ADC25prc) was used over the entire tumor volume and the overall level of 123I-mIBG uptake was graded into avidity groups. Results: No significant difference in whole-tumor ADC25prc values were found between different 123I-mIBG avidity groups pre- (P = 0.31) or postchemotherapy (P = 0.35). In the “intratumor” analysis, 5/15 patients (prechemotherapy) and 0/14 patients (postchemotherapy) showed a significant correlation between ADC and TLCR values (P < 0.05). Nonviable tumors had significantly lower postchemotherapy ADC25prc values than tumors with >10% viable tumor (P < 0.05). Both pre- and posttreatment TLCR values were significantly higher in patients with >50% viable tumor than those with 10–50% viable tumor (P < 0.05).
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