Abstract
ObjectiveRecent many studies have shown that whole body “diffusion-weighted imaging with background body signal suppression” (DWIBS) seems a beneficial tool having higher tumor detection sensitivity without ionizing radiation exposure for pediatric tumors. In this study, we evaluated the diagnostic performance of whole body DWIBS and 18F-FDG PET/CT for detecting lymph node and bone metastases in pediatric patients with neuroblastoma.MethodsSubjects in this retrospective study comprised 13 consecutive pediatric patients with neuroblastoma (7 males, 6 females; mean age, 2.9 ± 2.0 years old) who underwent both 18F-FDG PET/CT and whole-body DWIBS. All patients were diagnosed as neuroblastoma on the basis of pathological findings. Eight regions of lymph nodes and 17 segments of skeletons in all patients were evaluated. The images of 123I-MIBG scintigraphy/SPECT-CT, bone scintigraphy/SPECT, and CT were used to confirm the presence of lymph node and bone metastases. Two radiologists trained in nuclear medicine evaluated independently the uptake of lesions in 18F-FDG PET/CT and the signal-intensity of lesions in whole-body DWIBS visually. Interobserver difference was overcome through discussion to reach a consensus. The sensitivities, specificities, and overall accuracies of 18F-FDG PET/CT and whole-body DWIBS were compared using McNemer’s test. Positive predictive values (PPVs) and negative predictive values (NPVs) of both modalities were compared using Fisher’s exact test.ResultsThe total numbers of lymph node regions and bone segments which were confirmed to have metastasis in the total 13 patients were 19 and 75, respectively. The sensitivity, specificity, overall accuracy, PPV, and NPV of 18F-FDG PET/CT for detecting lymph node metastasis from pediatric neuroblastoma were 100, 98.7, 98.9, 95.0, and 100%, respectively, and those for detecting bone metastasis were 90.7, 73.1, 80.3, 70.1, and 91.9%, respectively. In contrast, the sensitivity, specificity, overall accuracy, PPV, and NPV of whole-body DWIBS for detecting bone metastasis from pediatric neuroblastoma were 94.7, 24.0, 53.0, 46.4 and 86.7%, respectively, whereas those for detecting lymph node metastasis were 94.7, 85.3, 87.2, 62.1, and 98.5%, respectively. The low specificity, overall accuracy, and PPV of whole-body DWIBS for detecting bone metastasis were due to a high incidence of false-positive findings (82/108, 75.9%). The specificity, overall accuracy, and PPV of whole-body DWIBS for detecting lymph node metastasis were also significantly lower than those of 18F-FDG PET/CT for detecting lymph node metastasis, although the difference between these 2 modalities was less than that for detecting bone metastasis.ConclusionThe specificity, overall accuracy, and PPV of whole-body DWIBS are significantly lower than those of 18F-FDG PET/CT because of a high incidence of false-positive findings particularly for detecting bone metastasis, whereas whole-body DWIBS shows a similar level of sensitivities for detecting lymph node and bone metastases to those of 18F-FDG PET/CT. DWIBS should be carefully used for cancer staging in children because of its high incidence of false-positive findings in skeletons.
Highlights
Neuroblastoma is the most common and malignant solid tumors of children [1], accounting for about 8% of all malignancy of children [2]
Whole-body “diffusion-weighted imaging with background body signal suppression” (DWIBS) which was introduced by Takahara et al [9] in 2004 has been increasingly used, and many studies confirmed that whole-body DWIBS is a feasible clinical technique for assessment of the original and metastatic lesions of adult patients with high sensitivity and accuracy [10,11,12,13,14]
All patients underwent 18F-FDG PET/ CT, whole-body DWIBS, 123I-meta-iodobenzylguanidine (123I-MIBG) scintigraphy/SPECT-CT, bone scintigraphy/ SPECT, and CT for the initial tumor staging within an interval of 20 days, 6 patients underwent them before starting the treatment, and 7 patients underwent them by at least 13 days after starting the treatment
Summary
Neuroblastoma is the most common and malignant solid tumors of children [1], accounting for about 8% of all malignancy of children [2]. 18F-FDG accumulates in primary and metastatic tumors of neuroblastoma, and the use of 18F-FDG PET or 18FFDG PET/CT for the diagnosis of patients with neuroblastoma is increasing [4,5,6,7,8]. There has been a case report which proposes diagnostic value of DWIBS for detecting metastases of pediatric neuroblastoma [21]. These studies suggest that DWIBS may be a beneficial tool having high detection sensitivity without ionizing radiation exposure for pediatric tumors
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