What is the prognostic value of osteomedullary uptake on MIBG scan in neuroblastoma patients under one year of age?

Comparison of diagnosing and staging accuracy of PET (CT) and MIBG on patients with neuroblastoma: Systemic review and meta-analysis

To perform a systemic review and meta-analysis of the diagnostic accuracy of PET (CT) and metaiodobenzylguanidine (MIBG) for diagnosing neuroblastoma (NB), electronic databases were searched as well as relevant references and conference proceedings. The diagnostic accuracy of MIBG and PET (CT) was calculated for NB, primary NB, and relapse/metastasis of NB based on their sensitivity, specificity, and area under the summary receiver operating characteristic curve (AUSROC) in terms of per-lesion and per-patient data. A total of 40 eligible studies comprising 1134 patients with 939 NB lesions were considered for the meta-analysis. For the staging of NB, the per-lesion AUSROC value of MIBG was lower than that of PET (CT) [0.8064±0.0414 vs. 0.9366±0.0166 (P<0.05)]. The per-patient AUSROC value of MIBG and PET (CT) for the diagnosis of NB was 0.8771±0.0230 and 0.6851±0.2111, respectively. The summary sensitivity for MIBG and PET (CT) was 0.79 and 0.89, respectively. The summary specificity for MIBG and PET (CT) was 0.84 and 0.71, respectively. PET (CT) showed higher per-lesion accuracy than MIBG and might be the preferred modality for the staging of NB. On the other hand, MIBG has a comparable diagnosing performance with PET (CT) in per-patient analysis but shows a better specificity.

Norepinephrine Transporter as a Target for Imaging and Therapy

The norepinephrine transporter (NET) is essential for norepinephrine uptake at the synaptic terminals and adrenal chromaffin cells. In neuroendocrine tumors, NET can be targeted for imaging as well as therapy. One of the most widely used theranostic agents targeting NET is metaiodobenzylguanidine (MIBG), a guanethidine analog of norepinephrine. ¹²³I/¹³¹I-MIBG theranostics have been applied in the clinical evaluation and management of neuroendocrine tumors, especially in neuroblastoma, paraganglioma, and pheochromocytoma. ¹²³I-MIBG imaging is a mainstay in the evaluation of neuroblastoma, and ¹³¹I-MIBG has been used for the treatment of relapsed high-risk neuroblastoma for several years, however, the outcome remains suboptimal. ¹³¹I-MIBG has essentially been only palliative in paraganglioma/pheochromocytoma patients. Various techniques of improving therapeutic outcomes, such as dosimetric estimations, high-dose therapies, multiple fractionated administration and combination therapy with radiation sensitizers, chemotherapy, and other radionuclide therapies, are being evaluated. PET tracers targeting NET appear promising and may be more convenient options for the imaging and assessment after treatment. Here, we present an overview of NET as a target for theranostics; review its current role in some neuroendocrine tumors, such as neuroblastoma, paraganglioma/pheochromocytoma, and carcinoids; and discuss approaches to improving targeting and theranostic outcomes.

123I-MIBG scintigraphy and 18F-FDG-PET imaging for diagnosing neuroblastoma

BACKGROUND

Neuroblastoma is an embryonic tumour of childhood that originates in the neural crest. It is the second most common extracranial malignant solid tumour of childhood.Neuroblastoma cells have the unique capacity to accumulate Iodine-123-metaiodobenzylguanidine (¹²³I-MIBG), which can be used for imaging the tumour. Moreover, ¹²³I-MIBG scintigraphy is not only important for the diagnosis of neuroblastoma, but also for staging and localization of skeletal lesions. If these are present, MIBG follow-up scans are used to assess the patient's response to therapy. However, the sensitivity and specificity of ¹²³I-MIBG scintigraphy to detect neuroblastoma varies according to the literature.Prognosis, treatment and response to therapy of patients with neuroblastoma are currently based on extension scoring of ¹²³I-MIBG scans. Due to its clinical use and importance, it is necessary to determine the exact diagnostic accuracy of ¹²³I-MIBG scintigraphy. In case the tumour is not MIBG avid, fluorine-18-fluorodeoxy-glucose ((18)F-FDG) positron emission tomography (PET) is often used and the diagnostic accuracy of this test should also be assessed.

OBJECTIVES

PRIMARY OBJECTIVES

1.1 To determine the diagnostic accuracy of ¹²³I-MIBG (single photon emission computed tomography (SPECT), with or without computed tomography (CT)) scintigraphy for detecting a neuroblastoma and its metastases at first diagnosis or at recurrence in children from 0 to 18 years old.1.2 To determine the diagnostic accuracy of negative ¹²³I-MIBG scintigraphy in combination with (18)F-FDG-PET(-CT) imaging for detecting a neuroblastoma and its metastases at first diagnosis or at recurrence in children from 0 to 18 years old, i.e. an add-on test.

SECONDARY OBJECTIVES

2.1 To determine the diagnostic accuracy of (18)F-FDG-PET(-CT) imaging for detecting a neuroblastoma and its metastases at first diagnosis or at recurrence in children from 0 to 18 years old.2.2 To compare the diagnostic accuracy of ¹²³I-MIBG (SPECT-CT) and (18)F-FDG-PET(-CT) imaging for detecting a neuroblastoma and its metastases at first diagnosis or at recurrence in children from 0 to 18 years old. This was performed within and between included studies. ¹²³I-MIBG (SPECT-CT) scintigraphy was the comparator test in this case.

SEARCH METHODS

We searched the databases of MEDLINE/PubMed (1945 to 11 September 2012) and EMBASE/Ovid (1980 to 11 September 2012) for potentially relevant articles. Also we checked the reference lists of relevant articles and review articles, scanned conference proceedings and searched for unpublished studies by contacting researchers involved in this area.

SELECTION CRITERIA

We included studies of a cross-sectional design or cases series of proven neuroblastoma, either retrospective or prospective, if they compared the results of ¹²³I-MIBG (SPECT-CT) scintigraphy or (18)F-FDG-PET(-CT) imaging, or both, with the reference standards or with each other. Studies had to be primary diagnostic and report on children aged between 0 to 18 years old with a neuroblastoma of any stage at first diagnosis or at recurrence.

DATA COLLECTION AND ANALYSIS

One review author performed the initial screening of identified references. Two review authors independently performed the study selection, extracted data and assessed the methodological quality.We used data from two-by-two tables, describing at least the number of patients with a true positive test and the number of patients with a false negative test, to calculate the sensitivity, and if possible, the specificity for each included study.If possible, we generated forest plots showing estimates of sensitivity and specificity together with 95% confidence intervals.

MAIN RESULTS

Eleven studies met the inclusion criteria. Ten studies reported data on patient level: the scan was positive or negative. One study reported on all single lesions (lesion level). The sensitivity of ¹²³I-MIBG (SPECT-CT) scintigraphy (objective 1.1), determined in 608 of 621 eligible patients included in the 11 studies, varied from 67% to 100%. One study, that reported on a lesion level, provided data to calculate the specificity: 68% in 115 lesions in 22 patients. The sensitivity of ¹²³I-MIBG scintigraphy for detecting metastases separately from the primary tumour in patients with all neuroblastoma stages ranged from 79% to 100% in three studies and the specificity ranged from 33% to 89% for two of these studies.One study reported on the diagnostic accuracy of (18)F-FDG-PET(-CT) imaging (add-on test) in patients with negative ¹²³I-MIBG scintigraphy (objective 1.2). Two of the 24 eligible patients with proven neuroblastoma had a negative ¹²³I-MIBG scan and a positive (18)F-FDG-PET(-CT) scan.The sensitivity of (18)F-FDG-PET(-CT) imaging as a single diagnostic test (objective 2.1) and compared to ¹²³I-MIBG (SPECT-CT) (objective 2.2) was only reported in one study. The sensitivity of (18)F-FDG-PET(-CT) imaging was 100% versus 92% of ¹²³I-MIBG (SPECT-CT) scintigraphy. We could not calculate the specificity for both modalities.

AUTHORS' CONCLUSIONS

The reported sensitivities of ¹²³-I MIBG scintigraphy for the detection of neuroblastoma and its metastases ranged from 67 to 100% in patients with histologically proven neuroblastoma.Only one study in this review reported on false positive findings. It is important to keep in mind that false positive findings can occur. For example, physiological uptake should be ruled out, by using SPECT-CT scans, although more research is needed before definitive conclusions can be made.As described both in the literature and in this review, in about 10% of the patients with histologically proven neuroblastoma the tumour does not accumulate ¹²³I-MIBG (false negative results). For these patients, it is advisable to perform an additional test for staging and assess response to therapy. Additional tests might for example be (18)F-FDG-PET(-CT), but to be certain of its clinical value, more evidence is needed.The diagnostic accuracy of (18)F-FDG-PET(-CT) imaging in case of a negative ¹²³I-MIBG scintigraphy could not be calculated, because only very limited data were available. Also the detection of the diagnostic accuracy of index test (18)F-FDG-PET(-CT) imaging for detecting a neuroblastoma tumour and its metastases, and to compare this to comparator test ¹²³I-MIBG (SPECT-CT) scintigraphy, could not be calculated because of the limited available data at time of this search.At the start of this project, we did not expect to find only very limited data on specificity. We now consider it would have been more appropriate to use the term "the sensitivity to assess the presence of neuroblastoma" instead of "diagnostic accuracy" for the objectives.

123I-meta-iodobenzylguanidine scintigraphy for the detection of neuroblastoma and pheochromocytoma: results of a meta-analysis

CONTEXT

(123)I-mIBG scintigraphy has been in clinical use for more than 20 yr for diagnostic assessment of patients with neural crest and neuroendocrine tumors. Prospective validation of the performance characteristics of this method has recently been published.

OBJECTIVE

A meta-analysis was performed to obtain best estimates of performance characteristics of (123)I-mIBG imaging for the two most common applications, evaluation of patients with neuroblastoma and pheochromocytoma.

DATA SOURCES

Articles published between 1980 and 2007 were identified from searches of multiple computer databases, including MEDLINE, BIOSIS, EMBASE, and SciSearch.

STUDY SELECTION

Primary inclusion criteria were: acceptable reference standard(s) for confirming subjects with disease (histopathology and/or a combination of imaging and catecholamine results); reference standards applied to all subjects who received (123)I-mIBG; and data on a minimum of 16 patients confirmed to have or not have the disease(s) under consideration. Two physician reviewers independently evaluated all articles against the inclusion/exclusion criteria. Twenty-two of 100 articles reviewed were included in the final analysis.

DATA EXTRACTION

The two reviewers extracted the data from eligible articles using a standardized form, capturing both study quality and efficacy information. Disagreements were resolved by consensus.

DATA SYNTHESIS

Sensitivity of (123)I-mIBG scans for detection of neuroblastoma was 97% [95% confidence interval (CI), 95 to 99%]; data were insufficient to estimate specificity. For pheochromocytoma, with application of the random-effects model, sensitivity and specificity were 94% (95% CI, 91-97%) and 92% (95% CI, 87-98%), respectively.

CONCLUSION

Based upon the literature, (123)I-mIBG scintigraphy has sensitivity and specificity greater than 90% for detection of neuroblastoma and pheochromocytoma.

PET/CT in the Evaluation of Neuroblastoma

I-123-metaiodobenzylguanidine (MIBG) is the most commonly used functional imaging agent in patients with neuroblastoma, but use of [F-18]- FDG PET is increasing. MIBG is useful for defining the extent of disease at diagnosis, following response to treatment, and localizing residual and recurrent disease. In early-stage disease, FDG is often better concentrated in tumor sites than MIBG. In all stages, disease extent in the chest, abdomen, and pelvis and local metastases may be better delineated by FDG. In advanced-stage disease, MIBG is superior for following the treatment response of metastatic tumor in the marrow and bone. Several C-11- and F-18-labeled tracers may be equal to or superior to I-123-MIBG if supply problems can be resolved.

Skeletal Involvement in Infants with Neuroblastoma a Quality Control Attempt

Aims and background

In 1994, French authors hypothesized that positive skeletal mIBG spots in infants with stage 4 neuroblastoma were not prognostically unfavorable unless associated to abnormal standard X-ray or CT findings. In 1999, the European Infant Neuroblastoma Study adopted this definition, indeed reducing the number of patients candidate to chemotherapy. Such an approach requires high quality scans and standardized procedures. The present study critically reviewed and assessed the quality of mIBG scans performed in Italian patients enrolled in the European Infant Neuroblastoma Study.

Methods

Three independent nuclear medicine specialists reviewed scans of 25 Italian patients enrolled in Trials 99.2, 99.3, and 99.4 of the European Infant Neuroblastoma Study between January 2000 and September 2002. An arbitrary quality score was attributed to each mIBG scintigraphy, ranging from 1 (less than adequate) to 3 (excellent). One radiologist and 2 oncologists reviewed the X-rays and CT scans and correlated the results with clinical assessment.

Results

The quality of mIBG scans was rated from good to excellent in 15 of 25 cases, poor in 4, and inadequate for diagnostic evaluation in 6. X-rays confirmed the presence of metastases in 3 of 7 cases with mIBG bone uptake. CT scan confirmed skull metastases in 6 of 9 mIBG-positive cases. Discrepancies in scan interpretation, making trial and stage attribution questionable, were found in 2 patients and are discussed.

Conclusions

The quality of mIBG scans proved to be at least acceptable in most Italian pediatric oncology centers. Efforts should be made to further standardize evaluation of the scans. Additional techniques (99mTc scintigraphy, MRI, SPECT) might be useful to help understand the most complex cases.

Scintigraphic response by 123I-metaiodobenzylguanidine scan correlates with event-free survival in high-risk neuroblastoma

PURPOSE

To investigate whether response to induction therapy, evaluated by metaiodobenzylguanadine (MIBG) and bone scintigraphy, correlates with event-free survival (EFS) in children with high-risk neuroblastoma (NB).

PATIENTS AND METHODS

Twenty-nine high-risk NB patients were treated prospectively with an intensive induction regimen and consolidated with three cycles of high-dose therapy with peripheral blood stem-cell rescue. The scintigraphic response was evaluated by MIBG and bone scans using a semi-quantitative scoring system. The prognostic significance of the imaging scores at diagnosis and following induction therapy was evaluated.

RESULTS

A trend associating worse 4-year EFS rates for patients with versus without osteomedullary uptake on MIBG scintigraphs at diagnosis was seen (35% +/- 11% v 80% +/- 18%, respectively; P =.13). Similarly, patients with positive bone scans at diagnosis had worse EFS than those with negative scans, although the difference did not receive statistical significance (34% +/- 10% v 83% +/- 15%, respectively; P =.06). However, significantly worse EFS was observed in patients with a postinduction MIBG score of >/= 3 compared to those with scores of less than 3 (0% v 58% +/- 11%; P =.002). There was no correlation between bone scan scores and outcome following induction therapy.

CONCLUSION

MIBG scores >/= 3 following induction therapy identifies a subset of NB patients who are likely to relapse following three cycles of high-dose therapy with peripheral blood stem-cell rescue, local radiotherapy, and 13-cis-retinoic acid. Alternative therapeutic strategies should be considered for patients with a poor response to induction therapy.

Adverse outcome of infants with metastatic neuroblastoma, MYCN amplification and/or bone lesions: results of the French society of pediatric oncology

To assess the relevance of MYCN amplification and bone lesions in stage 4 neuroblastoma (NB) in infants aged <1 year, 51 infants with stage 4 NB were enrolled. Three groups of patients were defined according to the type of metastases and the resectability of the primary tumour. Group I comprised 21 infants with radiologically detectable bone lesions, Group II 22 patients with an unresectable primary tumour and Group III eight patients with only metaiodobenzylguanidine (MIBG) skeletal uptake. MYCN oncogene content was assayed in 47/51 tumours and found to be amplified in 17 (37%). The 5-year event-free survival (EFS) rate of these 51 infants was 64.1% (+/- 7.1%). In a univariate analysis, bone lesions, MYCN amplification, urinary vanillylmandelic/homovanillic acid ratio and serum ferritin levels adversely influenced outcome. In the multivariate analysis, radiologically detectable bone lesions were the most powerful unfavourable prognostic indicator: the EFS rate was 27.2% for these infants compared to 90% for infants without bone lesions (P<0.0001). Our data emphasize the poor prognosis of infants affected by stage 4 NB with bone lesions, especially when associated with MYCN amplification. Given the poor results in this group whatever the treatment, new therapeutic approaches need to be investigated in the future.

Consolidation with a busulfan-containing regimen followed by stem cell transplantation in infants with poor prognosis stage 4 neuroblastoma

Although infants with stage 4 neuroblastoma (NB) usually have a good prognosis, metastatic relapses after 1 year of age and amplification of the N-myc oncogene are established poor prognostic factors. In order to improve the survival of patients with such high-risk factors, we performed consolidation with a busulfan (600 mg/m2)-melphalan (140 mg/m2)-containing regimen followed by autologous stem cell transplantation (SCT). From 1986 to 1998, 12 patients were treated according to this strategy. Their median age at diagnosis was 9 months (1-11). Consolidation was performed after a metastatic relapse in five children, because of persistent bone metastases in one and as first-line consolidation in six patients whose tumor exhibited N-myc amplification. The 5-year EFS rate is 64. 5% (36-85%) with a median follow-up of 92 months (20-126). One toxicity-related death occurred in a very heavily pretreated patient. Hepatic veno-occlusive disease was the major side-effect that occurred in nine of 12 children. This busulfan-melphalan combination appears to dramatically improve the prognosis of these high-risk infants with metastatic NB. Given its high toxicity, indications for this consolidation must be restricted to high-risk infants and a lower dose of busulfan (480 mg/m2) is recommended in children weighing less than 10 kg. Bone Marrow Transplantation (2000) 25, 937-942.

Metastatic sites in stage IV and IVS neuroblastoma correlate with age, tumor biology, and survival

PURPOSE

The goal of this study was to determine the incidence of metastatic sites in neuroblastoma and the extent to which metastatic sites correlate with age, tumor biology, and survival.

PATIENTS AND METHODS

All 648 patients with stage IV and IVS neuroblastoma registered on Children's Cancer Group protocols 3881 and 3891 were analyzed. Metastatic site data were provided by treating institutions and reviewed in patients with central nervous system (CNS), intracranial, lung, or "other" metastases.

RESULTS

The incidence of metastatic sites at diagnosis was 70.5% in bone marrow, 55.7% in bone, 30.9% in lymph nodes, 29.6% in liver, 18.2% in intracranial and orbital sites, 3.3% in lung, and 0.6% in CNS. Event-free survival (EFS) was decreased in patients with bone, bone marrow, CNS, intracranial/ orbital, lung, and pleural metastases, and improved in those with liver and skin metastases. In infants, MYCN amplification and unfavorable Shimada histopathology correlated with increased frequencies of bone and intracranial or orbital metastases. In older patients, MYCN amplification correlated with increased frequencies of intracranial or orbital, liver, and lung metastases. Multivariate analysis revealed that metastatic site is not an independent prognostic factor.

CONCLUSIONS

Metastatic pattern in neuroblastoma differs with age and correlates with tumor biological features and EFS. These correlations could reflect changes in host or tumor biological features with age resulting in differences in metastatic capacity or tumor affinity for specific sites.

Clinical impact and prognostic value of metaiodobenzylguanidine imaging in children with metastatic neuroblastoma

PURPOSE

The clinical value of metaiodobenzylguanidine (mIBG) scintigraphy in patients with disseminated neuroblastoma (NB) at the time of diagnosis and after induction chemotherapy was evaluated.

PATIENTS AND METHODS

The medical records and imaging studies of 30 patients with stage 4 NB who underwent mIBG scintigraphy and 99mTc hydroxy methylene diphosphonate bone scintigraphy at the time of diagnosis were reviewed. Scores were calculated for the mIBG and bone scintigrams, and outcome according to the initial and follow-up imaging studies was determined.

RESULTS

Discrepancies between bone scintigraphy and mIBG osteomedullary localization were seen in six patients. For the entire cohort, 2-year event-free survival did not significantly differ for the group of patients with initial mIBG or bone scintigraphy scores > or = 10 compared to those with scores < 10 (P = 0.23 and 0.61, respectively). However, for patients older than 1 year, a trend associating worse outcome with mIBG scores > or = 10 at diagnosis was seen (P = 0.08). A trend correlating abnormal mIBG scintigraphy after induction therapy and poor outcome was also observed (P = 0.09). Outcome did not correlate with the results of the bone scintigram studies performed after induction chemotherapy (P = 0.68).

CONCLUSION

Because a discordance between mIBG and bone scintigraphy results were seen in a subset of stage 4 NB patients, both imaging studies should be performed at the time of diagnosis. mIBG imaging studies performed at the time of diagnosis and after induction chemotherapy may be of prognostic value, particularly in stage 4 patients older than 1 year.

Stage IV neuroblastoma in patients over 1 year of age at diagnosis: consolidation of poor responders with combined busulfan, cyclophosphamide and melphalan followed by in vitro mafosfamide-purged autologous bone marrow transplantation

In an attempt to improve the poor prognosis of poor responders with stage IV neuroblastoma, a new combined high-dose chemotherapy conditioning regimen was tested. Event-free and overall survival, as well as the incidence of complications, were analysed. Twenty-five children aged 12-146 months at diagnosis entered this study. All were in complete remission (CR) at the time of high-dose chemotherapy. Two or three different protocols had been necessary for them to achieve a CR. High-dose chemotherapy consisted of a combination of busulfan (600 mg/m2), cyclophosphamide (4400 mg/m2) and melphalan (140 mg/m2). It was followed by autologous bone marrow transplantation (ABMT). The bone marrow graft was purged in vitro with mafosfamide. The probability of event-free survival (EFS) at 5 years post-ABMT was 34%, compared to < 8% in a historical series. Toxicity was severe but manageable and 2 complication-related deaths were observed. Veno-occlusive disease was the most frequent extrahaematopoietic complication encountered, but its outcome was always favourable. By using a very intensive conditioning regimen consisting of a combination of three alkylating agents, the EFS of poor responders with metastatic neuroblastoma was improved and similar to that of good responders. When compared with a previously published similar series of patients, the improvement in survival appears probably related to intensification of the conditioning regimen.

Metastatic neuroblastoma in children older than one year: prognostic significance of the initial metaiodobenzylguanidine scan and proposal for a scoring system

BACKGROUND

Metaiodobenzylguanidine (mIBG) is a guanethidine analog that has demonstrated a high sensitivity and specificity in detecting bone metastases in about 90% of metastatic neuroblastomas. However, the predictive value of initial mIBG scan in neuroblastoma patients older than 1 year of age regarding response to initial chemotherapy has yet to be ascertained. Therefore, a scoring system for grading the positivity of mIBG scans was devised and applied in a retrospective study in an attempt to determine whether this score had a prognostic value in neuroblastoma patients older than 1 year of age at diagnosis.

METHODS

Eighty-six children, older than 1 year of age, with metastatic neuroblastomas were homogeneously treated and had a mIBG scan performed at diagnosis and following the induction regimen to assess bone metastases. Each mIBG scan was assigned a reproducible score and the predictive value of the initial mIBG score was assessed in order to evaluate response to induction regimen.

RESULTS

The relative risk of failing to achieve complete remission after four courses of induction therapy was 6.9 times higher in patients who had more than four mIBG spots at diagnosis. A multivariate analysis including the established prognostic factors revealed that the initial mIBG score was the only significant factor (P < 0.001).

CONCLUSIONS

The initial mIBG scan is of prognostic significance to predict response to chemotherapy for metastatic neuroblastoma in children older than 1 year of age. A prospective study comparing this initial mIBG score with other recently established prognostic factors is warranted.

[Research on bone marrow involvement in the diagnosis of solid tumors in children. Methods, results and interpretation]

The assessment of bone marrow involvement by tumor cells remains an essential problem at diagnosis in pediatric solid tumors. Besides the conventional cytological and histological methods, some modern cell density separation techniques have been described in order to improve the detection of minimal or scattered bone marrow involvement. Immunological or genetical (molecular biology) tools can be used for the recognition of separated cells. In terms of investigations, MRI and MIBG radionucleide scan, although giving no definite proof, have the ability to macroscopically study the scattering of bone marrow invasion in the particular case of neuroblastoma. In some pediatric tumors, especially neuroblastomas and non Hodgkin lymphomas, an extensive bone marrow investigation is mandatory at diagnosis. Such an investigation is only necessary in case of particular criteria at diagnosis of Hodgkin's disease, Ewing' sarcomas, rhabdomyosarcomas and retinoblastomas. All other pediatric solid tumors do not need to be investigated in terms of bone marrow involvement at diagnosis, with the exceptions of advanced disseminated disease or if an autologous bone marrow transplantation is planned.