'Royal College of Obstetricians & Gynaecologists (RCOG)'
Abstract
Background: High-risk neuroblastoma (HR-NB) has a variable response to preoperative chemotherapy. It is not possible to
differentiate viable vs. nonviable residual tumor before surgery.
Purpose: To 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 Type: Retrospective.
Subjects: Forty patients with HR-NB.
Field Strength/Sequence: 1.5T 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).
Assessment: ADC 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 Tests: Analysis 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.
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). 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 Evidence: 4.
Technical Efficacy Stage: 3
