Pilot study of F18-Fluorodeoxyglucose Positron Emission Tomography/computerised tomography in Wilms’ tumour: Correlation with conventional imaging, pathology and immunohistochemistry

Congenital Mesoblastic Nephroma Mimic Wilms Tumor on 18 F-FDG PET/CT and PET/MR

ABSTRACT

Congenital mesoblastic nephroma is an extremely rare, low-grade malignant renal tumor in children. A 10-month-old boy and a 4-month-old girl were admitted to our hospital with a huge abdominal mass. For staging of the mass, 18 F-FDG PET/CT and PET/MR were performed showing a huge heterogeneous abdominal mass accompanied by extensive heterogeneous aggregation. Both of them were highly suspected to be Wilms tumor, the most common renal malignant tumor in children. However, histopathological examination after surgery confirmed congenital mesodermal nephroma.

Redo nephron-sparing surgery in stage V pediatric renal tumors - A report from the SIOP/GPOH study group for renal tumors

PURPOSE

Nephron-sparing Surgery (NSS) is the surgical treatment of choice in children with bilateral renal tumors or in syndromatic patients. With an increasing role of this surgical approach, there is also an increased number of tumor relapses after NSS. Aim of this study was to evaluate a second ("Redo-") NSS in children with relapsed renal tumors.

MATERIALS AND METHODS

We retrospectively analysed patients undergoing Redo-NSS for relapsed kidney tumors between 2009 and 2021 at our institution, which represents a national reference center of the SIOP/GPOH renal tumor study group.

RESULTS

Nine patients (5 girls, 4 boys) underwent Redo-NSS with resection of 15 lesions. Mean age at surgery was 58 months (12-137), mean operative time for Redo-NSS was 195 min (137-260). R0 resection status was achieved in all children. Two patients had second relapses, one of them was resected via NSS, the other child underwent tumor nephrectomy. Two patients with anaplastic relapses died from combined second relapses. Thus, 7/9 patients are alive without evidence of disease, an impaired renal function was observed in one child. Mean follow-up after Redo-NSS was 35 months (6-49).

CONCLUSIONS

In renal tumor relapses, Redo-NSS can be performed with satisfactory oncological and functional results. Occurrence of diffuse anaplasia should possibly refrain from this approach. Further evaluation in international multicenter analyses are necessary for a definitive determination of Redo-NSS.

PET/MRI in paediatric disease

Nuclear medicine and molecular imaging have a small but growing role in the management of paediatric and neonatal diseases. During the past decade, combined PET/MRI has emerged as a clinically important hybrid imaging modality in paediatric medicine due to diagnostic advantages and reduced radiation exposure compared to alternative techniques. The applications for nuclear medicine, radiopharmaceuticals and combined PET/MRI in paediatric diagnosis is broadly similar to adults, however there are some key differences. There are a variety of clinical applications for PET/MRI imaging in children including, but not limited to, oncology, neurology, cardiovascular, infection and chronic inflammatory diseases, and in renal-urological disorders. In this article, we review the applications of PET/MRI in paediatric and neonatal imaging, its current role, advantages and disadvantages over other hybrid imaging techniques such as PET/CT, and its future applications. Overall, PET/MRI is a powerful imaging technology in diagnostic medicine and paediatric diseases. Higher soft tissue contrasts and lower radiation dose of the MRI makes it the superior technology compared to other conventional techniques such as PET/CT or scintigraphy. However, this relatively new hybrid imaging has also some limitations. MRI based attenuation correction remains a challenge and although methodologies have improved significantly in the last decades, most remain under development.

SNMMI Procedure Standard/EANM Practice Guideline on Pediatric 18F-FDG PET/CT for Oncology 1.0

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and professional organization founded in 1954 to promote the science, technology, and practical application of nuclear medicine. The European Association of Nuclear Medicine (EANM) is a professional nonprofit medical association founded in 1985 to facilitate communication worldwide among individuals pursuing clinical and academic excellence in nuclear medicine. SNMMI and EANM members are physicians, technologists, and scientists specializing in the research and practice of nuclear medicine.

The SNMMI and EANM will periodically put forth new standards/guidelines for nuclear medicine practice to help advance the science of nuclear medicine and improve service to patients. Existing standards/guidelines will be reviewed for revision or renewal, as appropriate, on their fifth anniversary or sooner, if indicated. Each standard/guideline, representing a policy statement by the SNMMI/EANM, has undergone a thorough consensus process, entailing extensive review. The SNMMI and EANM recognize that the safe and effective use of diagnostic nuclear medicine imaging requires particular training and skills, as described in each document. These standards/guidelines are educational tools designed to assist practitioners in providing appropriate and effective nuclear medicine care for patients. These guidelines are consensus documents, and are not inflexible rules or requirements of practice. They are not intended, nor should they be used, to establish a legal standard of care. For these reasons and those set forth below, the SNMMI and the EANM cautions against the use of these standards/guidelines in litigation in which the clinical decisions of a practitioner are called into question.

The ultimate judgment regarding the propriety of any specific procedure or course of action must be made by medical professionals taking into account the unique circumstances of each case. Thus, there is no implication that action differing from what is laid out in the standards/guidelines, standing alone, is below standard of care. To the contrary, a conscientious practitioner may responsibly adopt a course of action different from that set forth in the standards/guidelines when, in the reasonable judgment of the practitioner, such course of action is indicated by the condition of the patient, limitations of available resources, or advances in knowledge or technology subsequent to publication of the standards/guidelines.

The practice of medicine involves not only the science, but also the art of dealing with the prevention, diagnosis, alleviation, and treatment of disease. The variety and complexity of human conditions make it impossible for general guidelines to consistently allow for an accurate diagnosis to be reached or a particular treatment response to be predicted. Therefore, it should be recognized that adherence to these standards/guidelines will not ensure a successful outcome. All that should be expected is that the practitioner follows a reasonable course of action, based on their level of training, the current knowledge, the available resources, and the needs/context of the particular patient being treated.

PET and computerized tomography (CT) have been widely used in oncology. ¹⁸F-FDG is the most common radiotracer used for PET imaging. The purpose of this document is to provide imaging specialists and clinicians guidelines for recommending, performing, and interpreting ¹⁸F-FDG PET/CT in pediatric patients in oncology. There is not a high level of evidence for all recommendations suggested in this paper. These recommendations represent the expert opinions of experienced leaders in this field. Further studies are needed to have evidence-based recommendations for the application of ¹⁸F-FDG PET/CT in pediatric oncology. These recommendations should be viewed in the context of good practice of nuclear medicine and are not intended to be a substitute for national and international legal or regulatory provisions.

Radiological response and histological findings in nephroblastoma: Is the any correlation?

INTRODUCTION

The Sociétè Internationale d'Oncologie Pédiatrique advocates for neoadjuvant chemotherapy in the management of nephroblastoma. Postoperatively, histological findings are used to assign risk classification to resected tumours. The aim of this study is to compare the response demonstrated by pre-operative imaging to the amount of necrosis seen on histology postoperatively.

PATIENTS AND METHODS

About 33 patients with nephroblastoma over a 10 year period had adequate imaging and histology records for this study. Three methods were used to assess tumour change following neoadjuvant therapy and were compared with histological records. 1. An estimation of necrosis, 2. Surface areas of apparent necrosis within the tumour measured on static imaging, 3. The change in volume of the mass. Pearson coefficient was calculated to measure the correlation between histologically observed necrosis and radiological changes. Results were considered significant if P< 0.05.

RESULTS

There was no correlation between radiological changes on pre-operative imaging and the percentage of necrosis seen on histology. Change in tumour size on radiological studies showed a moderate correlation to percentage tumour necrosis on histology but was unable to predict tumour risk classification.

CONCLUSIONS

In nephroblastoma, there is a moderate correlation between the decrease in size of a mass noted on imaging following chemotherapy and the degree of necrosis found postoperatively on histology. Change in tumour size cannot be used to predict histological risk classification. It is not possible to predict the histological risk classification of a nephroblastoma based on the changes demonstrated on non-contrasted magnetic resonance imaging or computed tomography preoperatively.

Association of Tumor [18F]FDG Activity and Diffusion Restriction with Clinical Outcomes of Rhabdomyosarcomas

PURPOSE

To evaluate whether the extent of restricted diffusion and 2-deoxy-2-[¹⁸F] fluoro-D-glucose ([¹⁸F]FDG) uptake of pediatric rhabdomyosarcomas (RMS) on positron emission tomography (PET)/magnetic resonance (MR) images provides prognostic information.

PROCEDURE

In a retrospective, IRB-approved study, we evaluated [¹⁸F]FDG PET/CT and diffusion-weighted (DW) MR imaging studies of 21 children and adolescents (age 1-20 years) with RMS of the head and neck. [¹⁸F]FDG PET and DW MR scans at the time of the initial tumor diagnosis were fused using MIM software. Quantitative measures of the tumor mass with restricted diffusion, [¹⁸F]FDG hypermetabolism, or both were dichotomized at the median and tested for significance using Gray's test. Data were analyzed using a survival analysis and competing risk model with death as the competing risk.

RESULTS

[¹⁸F]FDG PET/MR images demonstrated a mismatch between tumor areas with increased [¹⁸F]FDG uptake and restricted diffusion. The DWI, PET, and DWI + PET tumor volumes were dichotomized at their median values, 23.7, 16.4, and 9.5 cm³, respectively, and were used to estimate survival. DWI, PET, and DWI + PET overlap tumor volumes above the cutoff values were associated with tumor recurrence, regardless of post therapy COG stage (p = 0.007, p = 0.04, and p = 0.07, respectively).

CONCLUSION

The extent of restricted diffusion within RMS and overlap of hypermetabolism plus restricted diffusion predict unfavorable clinical outcomes.

The role of imaging in the initial investigation of paediatric renal tumours

Imaging has a key role in the assessment of paediatric renal tumours, especially when the initial treatment approach is to proceed to standard chemotherapy without histological confirmation. In Europe, according to the International Society of Paediatric Oncology guidelines, core needle biopsy is not routinely done unless the child is older than 10 years. Between age 6 months and 9 years, the child is treated with a standard regimen of preoperative chemotherapy unless there are concerns about non-Wilms' tumour pathology. Atypical imaging findings could therefore stratify a child into a different treatment protocol, and can prompt the need for pretreatment histology. This review details the latest protocols and techniques used in the assessment of paediatric renal tumours. Important imaging findings are discussed, especially the features that might prompt the need for a pretreatment biopsy. Local radiology practices vary, but both MRI and CT are widely used as routine imaging tests for the assessment of paediatric renal tumours in Europe. Advances in imaging technology and MRI sequences are facilitating the development of new techniques, which might increase the utility of imaging in terms of predicting tumour histology and clinical behaviour. Several of these new imaging techniques are outlined here.

Functional and anatomical imaging in pediatric oncology: which is best for which tumors

Functional imaging techniques are playing an increasingly important role in the management of pediatric cancer. Technological advances have pushed the development of hybrid imaging techniques, including positron emission tomography (PET)/CT, PET/MR and single-photon emission computed tomography (SPECT)/CT. Together with an increasing need to identify surrogate biomarkers for response to novel therapies, the use of functional imaging techniques, which had been reserved primarily for lymphoma patients, is now being recognized as standard of care for the management of many other pediatric solid tumors. The purpose of this review is to summarize recent data describing the use of functional and metabolic imaging strategies for the staging and response assessment of common pediatric solid tumors, and to offer some guidance as to which techniques are most appropriate for which tumor types.

18F-FDG PET-CT in paediatric oncology: established and emerging applications

Accurate staging and response assessment is vital in the management of childhood malignancies. Fluorine-18 fluorodeoxyglucose positron emission tomography/CT (FDG PET-CT) provides complimentary anatomical and functional information. Oncological applications of FDG PET-CT are not as well-established within the paediatric population compared to adults. This article will comprehensively review established oncological PET-CT applications in paediatric oncology and provide an overview of emerging and future developments in this domain.

Lymph node imaging of pediatric renal and suprarenal malignancies

Pediatric renal and suprarenal cancers are relatively rare malignancies, but are not without significant consequence to both the patient and caretakers. These tumors are often found incidentally and present as large abdominal masses. Standard of care management involves surgical excision of the mass, but contemporary treatment guidelines advocate for use of neoadjuvant or adjuvant chemotherapy for advanced stage disease, such as those cases with lymph node involvement (LNI). However, LNI detection is based primarily on surgical pathology and performing extended lymph node dissection can add significant morbidity to a surgical case. In this review, we focus on the use and performance of imaging modalities to detect LNI in Wilms’ tumor (WT), neuroblastoma, and pediatric renal cell carcinoma (RCC). We report on how imaging impacts management of these cases and the clinical implications of LNI. A literature search was conducted for studies published on imaging-based detection of LNI in pediatric renal and suprarenal cancers. Further review focused on surgical and medical management of those cases with suspected LNI. Current imaging protocols assisting in diagnosis and staging of pediatric renal and suprarenal cancers are generally limited to abdominal ultrasound and cross-sectional imaging, mainly computed tomography (CT). Recent research has investigated the role of more advance modalities, such as magnetic resonance imaging (MRI) and positron emission tomography (PET), in the management of these malignancies. Special consideration must be made for pediatric patients who are more vulnerable to ionizing radiation and have characteristic imaging features different from adult controls. Management of pediatric renal and suprarenal cancers is influenced by LNI, but the rarity of these conditions has limited the volume of clinical research regarding imaging-based staging. As such, standardized criteria for LNI on imaging are lacking. Nevertheless, advanced imaging modalities are being investigated and potentially represent more accurate and safer options.

Nuclear Medicine in Pediatric Nephro-Urology: An Overview

In the context of ante-natally diagnosed hydronephrosis, the vast majority of children with a dilated renal pelvis do not need any surgical treatment, as the dilatation resolves spontaneously with time. Slow drainage demonstrated at Tc-99m-mercaptoacetyltriglycine (MAG3) renography does not necessarily mean obstruction. Obstruction is defined as resistance to urinary outflow with urinary stasis at the level of the pelvic-ureteric junction (PUJ) which, if left untreated, will damage the kidney. Unfortunately this definition is retrospective and not clinically helpful. Therefore, the identification of the kidney at risk of losing function in an asymptomatic patient is a major research goal. In the context of renovascular hypertension a DMSA scan can be useful before and after revascularisation procedures (angioplasty or surgery) to assess for gain in kidney function. Renal calculi are increasingly frequent in children. Whilst the vast majority of patients with renal stones do not need functional imaging, DMSA scans with SPECT and a low dose limited CT can be very helpful in the case of complex renal calculi. Congenital renal anomalies such as duplex kidneys, horseshoe kidneys, crossed-fused kidneys and multi-cystic dysplastic kidneys greatly benefit from functional imaging to identify regional parenchymal function, thus directing further management. Positron emission tomography (PET) is being actively tested in genito-urinary malignancies. Encouraging initial reports suggest that F-18-fluorodeoxyglucose (FDG) PET is more sensitive than CT in the assessment of lymph nodal metastases in patients with genito-urinary sarcomas; an increased sensitivity in comparison to isotope bone scans for skeletal metastatic disease has also been reported. Further evaluation is necessary, especially with the promising advent of PET/MRI scanners. Nuclear Medicine in paediatric nephro-urology has stood the test of time and is opening up to new exciting developments.

Renal Tumors of Childhood: Radiologic-Pathologic Correlation Part 1. The 1st Decade: From the Radiologic Pathology Archives

Wilms tumor is the second most common pediatric solid tumor and by far the most common renal tumor of infants and young children. As most tumors are large at presentation and are treated with nephrectomy, the role of imaging is primarily in preoperative planning and evaluation for metastatic disease. However, with treatment protocols increasingly involving use of preoperative (neoadjuvant) chemotherapy (the standard in Europe) and consideration of nephron-sparing surgery, the role of imaging is evolving to include providing initial disease staging information and a presumptive diagnosis to guide therapy. Differential diagnostic considerations include lesions that are clinically benign and others that require more intensive therapy than is used to treat Wilms tumor. In part 1 of this article, the unique histologic spectrum of renal neoplasms of infants and young children is reviewed with emphasis on radiologic-pathologic correlation. Part 2 will focus on renal tumors of older children and adolescents.

Asymptomatic Mesenchymal Hamartoma of the Chest Wall in Child With Fluorodeoxyglucose Uptake on PET/CT-Report of a Case

We had experience with a case of mesenchymal hamartoma of the chest wall (MHCW) with fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT). We reported the first case of asymptomatic MHCW in a child with preoperative PET/CT. Mesenchymal hamartoma of the chest wall is a rare benign tumor that usually presents as a visible chest wall mass or respiratory problems secondary to compression of the lung in early infancy. It is often reported that malignant transformation is extraordinarily rare. Positron emission tomography/CT is useful for diagnosis of malignancy. There is no report of MHCW in a child with preoperative PET/CT before. We examined an asymptomatic 1-year-old girl with an incidental finding on a chest x-ray. Scans of CT and PET/CT were performed before surgical resection. After surgery, the resected tumor was examined histologically. Chest x-ray and CT scan of the chest confirmed a 25- × 20-mm round shaped intrapleural mass containing calcification and destructing the rib, arising from the third rib. Scan of PET/CT demonstrated the mass with light FDG accumulation. Histologically, the mass was homogenous, with thick funicular of hyaline cartilage interdigitating with scattered fiber. There were no malignant cells. No malignant MHCW was demonstrated in the mass, with light FDG accumulation by PET/CT. PET/CT might be a useful tool to distinguish malignant MHCW in children.

Value of 18F-FDG PET and PET/CT for evaluation of pediatric malignancies

Successful management of solid tumors in children requires imaging tests for accurate disease detection, characterization, and treatment monitoring. Technologic developments aim toward the creation of integrated imaging approaches that provide a comprehensive diagnosis with a single visit. These integrated diagnostic tests not only are convenient for young patients but also save direct and indirect health-care costs by streamlining procedures, minimizing hospitalizations, and minimizing lost school or work time for children and their parents. (18)F-FDG PET/CT is a highly sensitive and specific imaging modality for whole-body evaluation of pediatric malignancies. However, recent concerns about ionizing radiation exposure have led to a search for alternative imaging methods, such as whole-body MR imaging and PET/MR. As we develop new approaches for tumor staging, it is important to understand current benchmarks. This review article will synthesize the current literature on (18)F-FDG PET/CT for tumor staging in children, summarizing questions that have been solved and providing an outlook on unsolved avenues.

Is there a role for PET-CT and SPECT-CT in pediatric oncology?

During the last decade, hybrid imaging has revolutionized nuclear medicine. Multimodal camera systems, integrating positron emission tomography (PET) or single photon emission computed tomography (SPECT) with computed tomography (CT) now combine the contrast provided by tumor-avid radioactive drugs with the anatomic precision of CT. While PET-CT to a great extent has replaced single-modality PET in adult oncology, the use of PET-CT in children has been controversial, since even the lowest dose CT protocols adds approximately 2 mSv to the radiation dose of about 4 mSv from the PET-study with F-18-fluorodeoxyglucose (F-18-FDG). The article describes the current techniques used, discusses radiation doses and gives an overview of current indications for PET-CT and SPECT-CT in children. Hybrid imaging with a tumor-avid radioactive drug provides extremely high contrast between tumor and background tissues, while the CT component helps to locate the lesion anatomically. Currently both PET-CT and SPECT-CT play a role in pediatric oncology; PET-CT using F-18-FDG particularly for staging and follow-up of lymphoma and brain cancer, bone and soft tissue sarcomas; SPECT-CT with I-123-metaiodobenzylguanidine (MIBG) for tumors of the sympathetic nervous system such as neuroblastoma and pheochromocytoma while the remaining neuroendocrine tumors are imaged with radioactively labeled somatostatin analogues. To reduce radiation dose, a low-dose CT in combination with ultrasound and/or magnetic resonance imaging for the assessment of anatomy is often preferred.

Is there a role for FDG-PET for the assessment of treatment efficacy in Wilms' tumor? A case report and literature review

BACKGROUND

The role of FDG-PET in Wilms' tumor has not been well established. The aim of this report is to describe the role of FDG-PET to assess chemotherapy efficacy and to show potential correlations between different Standardized Uptake Values (SUVs) and histopathological features in a patient with persisting metastatic disease.

CASE DESCRIPTION

A 3-year-old boy was diagnosed with Wilms' tumor without anaplasia. The patient underwent treatment as according to the AIEOP-TW-2003 protocol, for stage III tumors. Therapy was discontinued with no evidence of disease, yet 9 months later thorax metastases were found. Although second and third line treatments were administered, conventional imaging demonstrated stable disease. Metronomic chemotherapy as well was employed for 44 months and FDG-PET was annually performed basing on responsible local physician choice trying to better describe the disease status. Four months after fourth line treatment was stopped, the patient manifested clinical symptoms; lesions began to increase their metabolic activity inhomogeneously. Therapy was hence restarted and SUVs decreased. Metastasectomies were then performed and histology revealed a correlation between viable disease shown by higher FDG-PET uptake and viable tumor areas.

CONCLUSIONS

Our case discussion demonstrates that FDG-PET is potentially valuable in Wilms' tumor correlating SUV values and histological features of the tumor after chemotherapy. This case suggests that FDG-PET is a valid tool to assess chemotherapy response in relapsed Wilms' tumor even in case of no evidence of significant dimensional changes under conventional imaging.

Potential Clinical Applications of PET/Magnetic Resonance Imaging

Hybrid PET/magnetic resonance (MR) imaging, which combines the excellent anatomic information and functional MR imaging parameters with the metabolic and molecular information obtained with PET, may be superior to PET/computed tomography or MR imaging alone for a wide range of disease conditions. This review highlights potential clinical applications in neurologic, cardiovascular, and musculoskeletal disease conditions, with special attention to applications in oncologic imaging.

Immunohistochemical expression of GLUT1 and its correlation with unfavorable histology and TP53 codon 72 polymorphism in Wilms tumors

Reprogramming of energy metabolism, such as increased glycolysis, is a hallmark of cancer cells. One mechanism by which cancer cells fuel glycolysis is through increased uptake of glucose across cell membranes via the glucose transporter GLUT1. One of the transcriptional repressors of GLUT1 is wild-type TP53, and cancer-associated loss of function mutations within the DNA-binding domain of TP53 impairs the repressive effect of TP53 on transcriptional activity of the GLUT1 gene promoter. Because TP53 mutations are associated with unfavorable histology (diffuse anaplasia) in Wilms tumors, we hypothesized increased expression of GLUT1 in these tumors. To evaluate this hypothesis, we performed tissue microarray-based immunohistochemistry for GLUT1 in a set of 50 Wilms tumors, including 5 with unfavorable histology. In a subset of 16 favorable histology Wilms tumors, we compared the GLUT1 immunoexpression with TP53 codon 72 polymorphism status. We found consistently stronger immunoexpression of GLUT1 in unfavorable histology Wilms tumors compared to favorable histology Wilms tumors (P  =  0.04). We noted that the favorable histology Wilms tumors with a proline residue at position 72 of TP53 tended to have higher immunoexpression of GLUT1, although this immunoexpression did not reach statistical significance in this small set of cases. In summary, our finding of strong GLUT1 immunoexpression in unfavorable histology Wilms tumors indicates that these tumors are likely to be 2-deoxy-2-((18)F)fluoro-d-glucose avid and that GLUT1 should be evaluated as a therapeutic target for these tumors that otherwise show resistance to conventional therapy.

Pediatric genitourinary tumors

PURPOSE OF REVIEW

To review the 2009/2010 literature on pediatric genitourinary tumors and highlight the most significant publications.

RECENT FINDINGS

New techniques such as gene expression profiling, PET, nephron-sparing surgery, and stem cell transplantation are being incorporated into contemporary treatments for pediatric patients with genitourinary tumors. Biologic markers are increasingly being used to help with risk stratification of patients. WT1 mutation and 11p15 loss of heterozygosity have been associated with relapse in very low-risk Wilms tumors treated with surgery alone and may help reduce the use of chemotherapy in some children. Discussion continues on the use of fusion gene status to risk stratify alveolar rhabdomyosarcoma. Meta-analysis of the use of high-dose chemotherapy with autologous hematopoetic stem cell rescue in patients with relapsed Wilms tumor and rhabdomyosarcoma suggests that some patients may benefit more from conventional salvage chemotherapy. New agents are needed for patients with high-risk and relapsed disease to improve outcomes.

SUMMARY

In general, the prognosis for patients with pediatric genitourinary tumors is favorable. The elucidation of the molecular abnormalities in these tumors is determining risk stratification, treatment strategies, and candidates for new drug development.

PET-CT in children: where is it appropriate?

The use of PET/PET-CT is a rapidly growing area of imaging and research in the care of children. Until recently, diagnostic imaging methods have provided either anatomical or functional assessment. The development of fused imaging modalities, such as PET-CT or PET-MRI, now provides the opportunity for simultaneously providing both anatomical and functional or physiological assessment. This review will discuss current established uses of PET-CT, possible uses and potential research investigations in the use of this modality in the pediatric population. The focus of this paper will be its use in children being treated for non-central nervous system and non-cardiac disorders.

Pediatric oncology and the future of oncological imaging

The future of pediatric oncology will be influenced by changes in drug design and treatment strategy, with genomic medicine and molecular-based diagnostics and therapeutics playing increasingly important roles. The role of imaging as a means of measuring response to therapy has also evolved, with the development of new technologies and higher sensitivity means of detecting tumors. Conventional anatomical imaging techniques are being increasingly supplemented with functional techniques, including FDG-PET imaging and diffusion-weighted MR imaging. The risk-adapted treatment regimens of the past, which led to improved event-free and overall survival in many pediatric cancers, have paved the way for new response-based treatment paradigms. Response-based approaches seek to identify patients with a high likelihood of cure, treating them less aggressively, while those not responding to therapy are identified early and redirected into more aggressive therapeutic regimens. These advances will require concurrent development of imaging biomarkers as surrogates of early response to therapy. Incorporating these techniques into new response-directed treatment algorithms will be crucial as personalized medicine and molecular-targeted, tumor-specific therapies gain acceptance for the treatment of children with cancer.