Variations in apparent diffusion coefficient values following chemotherapy in pediatric neuroblastoma

Abstract

ORIGINAL ARTICLE PURPOSEIn children the assessment of solid tumors' response to chemotherapy is based primarily on size reduction, which can be unreliable and a late marker, in the presence of necrosis. We aimed to establish whether apparent diffusion coefficient (ADC) values of childhood neuroblastomas show proportional changes in relation to chemotherapy response. METHODSWe evaluated 15 pediatric patients with abdominopelvic neuroblastomas, who had undergone MRI before and after chemotherapy. Two radiologists retrospectively analyzed all images by drawing a round uniform region-of-interest in the solid/contrast-enhancing portion of the lesions in consensus.The ADC values from pre-and postchemotherapy images were compared. RESULTSPostchemotherapy ADC values were significantly higher than those obtained before treatment (P < 0.05, for minimum, maximum, and median ADC values). CONCLUSIONOur results support diffusion-weighted MRI as a promising noninvasive biomarker of therapeutic responses. To the best of our knowledge, this is the first report to compare diffusionweighted imaging findings before and after chemotherapy in childhood neuroblastic tumors. The ADC values of malignant masses are relatively lower than those of benign masses, although overlapping ADC values of malignant and benign lesions have also been reported (1, 6-12). Currently, in children the assessment of solid tumors' response to chemotherapy is based on size reduction; but this method can be unreliable as a marker, as tumors that shrink substantially may still be composed mainly of malignant cells (13,14).Here, we aimed to evaluate whether ADC values in viable portions of childhood neuroblastomas show any changes depending on tumor cellularity before and after chemotherapy. We hypothesized that an increase in ADC values over the course of chemotherapy could be used as a noninvasive marker of therapy response. To the best of our knowledge, this is the first report to compare DW-MRI findings before and after chemotherapy in childhood neuroblastic tumors. Methods PatientsWe retrospectively screened pediatric patients who had neuroblastic tumors and received treatment at our hospital between January 2009 and August 2013. We found 36 pediatric patients who underwent routine protocol-driven MRI assessment for solid tumors. Out of this group we acquired data from children who had intra-abdominal neuroblastic tumors that were diagnosed histopathologically. Our institution generally prefers MRI over computed tomography; however, due to capacity and time restrictions, not all patients undergo MRI both at primary diagnosis and at postchemotherapy follow-up. Only those patients who underwent MRI before and after chemotherapy were included in this study. In addition, exclusion criteria included any oncological (chemotherapy or radiotherapy) or surgical treatment before initial imaging. Consequently, we evaluated 15 patients between 4-138 months of age (mean, 37.8 months) including five females and 10 males. Thirteen patients were Stage 4 and two patients w...

Diagnostic Value of Diffusion-Weighted MRI for Tumor Characterization, Differentiation and Monitoring in Pediatric Patients with Neuroblastic Tumors

“…Preliminary results suggest that, based on apparent diffusion coefficient (ADC) values, DWI can indeed distinguish between NB, GNB and GN with some confidence [10,11]. Recent reports confirm these findings [12] and propose diagnostic value for detecting metastases [13] and for monitoring therapy response [14].…”

“…Demir et al [14] recorded significantly higher mean, maximum and minimum values for tumor ADC in 15 children undergoing DWI at 1.5 T (Magnetom Symphony and Magnetom Avanto) of 1.05 with therapy, compared to 0.74 on pre-therapy DWI, using a small ROI approach. These data are virtually identical to the data obtained with the small ROI evaluation in our study (▶ Table 1), further supporting our notion of good reproducibility of ADC quantification when using similar equipment and scanning parameters.…”

Diagnostic performance of 18F-FDG PET/CT and whole-body diffusion-weighted imaging with background body suppression (DWIBS) in detection of lymph node and bone metastases from pediatric neuroblastoma

“…In pediatric patients, DWIBS has been confirmed, based on ADC values of the original lesions, to discriminate between benign and malignant tumors including neuroblastic tumors [ 15 – 19 ] and also to efficiently judge response to chemotherapy in pediatric neuroblastoma [ 20 ]. In adult patients, however, there have been reports indicating that signal intensity of the lesion-to spinal cord ratio (LSR) measured on high b-value DWIBS is more useful than ADC for differentiating between benign and malignant lung nodules [ 23 , 24 ].…”

“…In the field of pediatric oncology, it has recently been demonstrated that, based on apparent diffusion coefficient (ADC) values, DWIBS can discriminate between benign and malignant abdominal mass lesions [ 15 ], between neuroblastoma and ganglioneuroma/ganglioneuroblastoma [ 16 – 18 ], and between neuroblastoma and Wilms tumor [ 19 ]. Change in ADC values is useful for efficiently judging response to chemotherapy in pediatric neuroblastoma [ 20 ]. There has also been a case report which proposes diagnostic value of DWIBS for detecting metastases of pediatric neuroblastoma [ 21 ].…”

Lymph node imaging of pediatric renal and suprarenal malignancies

“…In general, both CT and MRI have low positive predictive value for LNI, but the inclusion of additional pulse sequences, such as diffusion weighted imaging, as part of a multiparametric MRI may improve positive lymph node detection ( 4 ). Use of ADC mapping values calculated from diffusion-weighted imaging with background body signal suppression (DWIBS) has been shown to differentiate NB from other abdominal lesions, both benign and malignant, and gauge response to chemotherapy ( 38 , 39 ).…”