Oncologic PET/MRI, Part 2: Bone Tumors, Soft-Tissue Tumors, Melanoma, and Lymphoma

Musculoskeletal Lymphoma: Imaging Features, Diagnosis, and Assessment of Treatment Response

Lymphoma, a diverse group of neoplasms, has been frequently refined in classification, with over 100 types identified by the World Health Organization in 2022. Lymphoma represents 5% of new malignancies in the United States, the risk factors of which include genetic predisposition, infections, and inflammatory conditions. Extranodal lymphoma, constituting 25%-40% of cases, uncommonly involves the musculoskeletal system, with diffuse large B-cell lymphoma being the primary type. Bone lymphoma, classified as primary, primary multifocal, or secondary, predominantly affects the appendicular skeleton. Radiography and CT aid osseous evaluation and may reveal a lytic, sclerotic, mixed lytic and sclerotic, or near-normal appearance. MRI excels in soft-tissue and bone marrow assessment, and PET/CT plays a pivotal role in staging. Soft-tissue lymphoma, which involves various compartments, is best characterized with MRI, whereas US may be the modality first used for evaluation. Staging involves fluorodeoxyglucose (FDG) PET/CT, and treatment response is assessed through various imaging modalities. Skin involvement, commonly associated with primary cutaneous T-cell lymphoma, is described through stages, with FDG PET aiding diagnosis. Transspatial lymphoma involves multiple contiguous spaces and is known in the head and neck but not well documented in the musculoskeletal system. The authors provide comprehensive insight into musculoskeletal lymphoma by highlighting imaging findings crucial for diagnosis, classification, staging, and assessment of treatment response. ©RSNA, 2025.

Imaging of Peripheral Intraneural Tumors: A Comprehensive Review for Radiologists

BACKGROUND/OBJECTIVES

Intraneural tumors (INTs) pose a diagnostic challenge, owing to their varied origins within nerve fascicles and their wide spectrum, which includes both benign and malignant forms. Accurate diagnosis and management of these tumors depends upon the skills of the radiologist in identifying key imaging features and correlating them with the patient's clinical symptoms and examination findings.

METHODS

This comprehensive review systematically analyzes the various imaging features in the diagnosis of intraneural tumors, ranging from basic MR to advanced MR imaging techniques such as MR neurography (MRN), diffusion tensor imaging (DTI), and dynamic contrast-enhanced (DCE) MRI.

RESULTS

The article emphasizes the differentiation of benign from malignant lesions using characteristic MRI features, such as the "target sign" and "split-fat sign" for tumor characterization. The role of advanced multiparametric MRI in improving biopsy planning, guiding surgical mapping, and enhancing post-treatment monitoring is also highlighted. The review also underlines the importance of common diagnostic pitfalls and highlights the need for a multi-disciplinary approach to achieve an accurate diagnosis, appropriate treatment strategy, and post-therapy surveillance planning.

CONCLUSIONS

In this review, we illustrate the main imaging findings of intraneural tumors, focusing on specific MR imaging features that are crucial for an accurate diagnosis and the differentiation between benign and malignant lesions.

Diagnosis and Treatment of Myxoid Liposarcoma

OPINION STATEMENT

Myxoid liposarcoma (MLS) is a rare subtype of soft tissue sarcoma that distinguishes itself from conventional subtypes through its propensity for extrapulmonary metastasis. The distinctive magnetic resonance imaging (MRI) characteristics of MLS render it an invaluable tool for identifying primary and secondary lesions. Pathologically, MLS is characterized by the FUS-DDIT3 gene fusion. Accurate diagnosis, facilitated by MRI and pathological assessment, is critical for prognostication and the formulation of appropriate treatment strategies. Surgery remains the cornerstone of local management for MLS. The combination of surgery and radiotherapy can significantly reduce the local recurrence rate in MLS, as it is highly sensitive to both radiotherapy and chemotherapy. Additionally, for high-risk MLS cases with a large tumor diameter, chemotherapy has been shown to improve survival. The comprehensive treatment approach for MLS demonstrates superior local recurrence rates and survival rates compared to most soft tissue sarcomas. Current research focuses on developing effective therapies for unresectable or advanced disease based on genomic and phenotypic characteristics as well as the immune-tumor microenvironment.

PET/CT Imaging in Treatment Planning and Surveillance of Sinonasal Neoplasms

Sinonasal cancers are uncommon malignancies with a generally unfavorable prognosis, often presenting at an advanced stage. Their high rate of recurrence supports close imaging surveillance and the utilization of functional imaging techniques. Whole-body 18F-FDG PET/CT has very high sensitivity for the diagnosis of sinonasal malignancies and can also be used as a "metabolic biopsy" in the characterization of some of the more common subgroups of these tumors, though due to overlap in uptake, histological confirmation is still needed. For certain tumor types, radiotracers, such as 11C-choline, and radiolabeled somatostatin analogs, including 68Ga-DOTATATE/DOTATOC, have proven useful in treatment planning and surveillance. Although serial scans for posttreatment surveillance allow the detection of subclinical lesions, the optimal schedule and efficacy in terms of survival are yet to be determined. Pitfalls of 18F-FDG, such as post-surgical and post-radiotherapy crusting and inflammation, may cause false-positive hypermetabolism in the absence of relapse.

Imaging of pediatric bone tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Malignant primary bone tumors are uncommon in the pediatric population, accounting for 3%-5% of all pediatric malignancies. Osteosarcoma and Ewing sarcoma comprise 90% of malignant primary bone tumors in children and adolescents. This paper provides consensus-based recommendations for imaging in children with osteosarcoma and Ewing sarcoma at diagnosis, during therapy, and after therapy.

18F-FDG PET/CT in the Management of Osteosarcoma

Osteosarcoma is the most common type of primary malignant bone tumor. ¹⁸F-FDG PET/CT is useful for staging, detecting recurrence, monitoring response to neoadjuvant chemotherapy, and predicting prognosis. Here, we review the clinical aspects of osteosarcoma management and assess the role of ¹⁸F-FDG PET/CT, in particular with regard to pediatric and young adult patients.

Correlation between Imaging Markers Derived from PET/MRI and Invasive Acquired Biomarkers in Newly Diagnosed Breast Cancer

PURPOSE

Evaluate the diagnostic potential of [¹⁸F]FDG-PET/MRI data compared with invasive acquired biomarkers in newly diagnosed early breast cancer (BC).

METHODS

Altogether 169 women with newly diagnosed BC were included. All underwent a breast- and whole-body [¹⁸F]FDG-PET/MRI for initial staging. A tumor-adapted volume of interest was placed in the primaries and defined bone regions on each standard uptake value (SUV)/apparent diffusion coefficient (ADC) dataset. Immunohistochemical markers, molecular subtype, tumor grading, and disseminated tumor cells (DTCs) of each patient were assessed after ultrasound-guided biopsy of the primaries and bone marrow (BM) aspiration. Correlation analysis and group comparisons were assessed.

RESULTS

A significant inverse correlation of estrogen-receptor (ER) expression and progesterone-receptor (PR) expression towards SUV_max was found (ER: r = 0.27, p < 0.01; PR: r = 0.19, p < 0.05). HER2-receptor expression showed no significant correlation towards SUV and ADC values. A significant positive correlation between Ki67 and SUVmax and SUV_mean (r = 0.42 p < 0.01; r = 0.19 p < 0.05) was shown. Tumor grading significantly correlated with SUV_max and SUV_mean (ρ = 0.36 and ρ = 0.39, both p's < 0.01). There were no group differences between SUV/ADC values of DTC-positive/-negative patients.

CONCLUSIONS

[¹⁸F]FDG-PET/MRI may give a first impression of BC-receptor status and BC-tumor biology during initial staging by measuring glucose metabolism but cannot distinguish between DTC-positive/-negative patients and replace biopsy.

PET/MR of pediatric bone tumors: what the radiologist needs to know

Integrated 2-deoxy-2-[fluorine-18]fluoro-D-glucose (18F-FDG) positron emission tomography (PET)/magnetic resonance (MR) imaging can provide "one stop" local tumor and whole-body staging in one session, thereby streamlining imaging evaluations and avoiding duplicate anesthesia in young children. 18F-FDG PET/MR scans have the benefit of lower radiation, superior soft tissue contrast, and increased patient convenience compared to 18F-FDG PET/computerized tomography scans. This article reviews the 18F-FDG PET/MR imaging technique, reporting requirements, and imaging characteristics of the most common pediatric bone tumors, including osteosarcoma, Ewing sarcoma, primary bone lymphoma, bone and bone marrow metastases, and Langerhans cell histiocytosis.

SELNET clinical practice guidelines for bone sarcoma

Bone sarcoma are infrequent diseases, representing < 0.2% of all adult neoplasms. A multidisciplinary management within reference centers for sarcoma, with discussion of the diagnostic and therapeutic strategies within an expert multidisciplinary tumour board, is essential for these patients, given its heterogeneity and low frequency. This approach leads to an improvement in patient's outcome, as demonstrated in several studies. The Sarcoma European Latin-American Network (SELNET), aims to improve clinical outcome in sarcoma care, with a special focus in Latin-American countries. These Clinical Practice Guidelines (CPG) have been developed and agreed by a multidisciplinary expert group (including medical and radiation oncologist, surgical oncologist, orthopaedic surgeons, radiologist, pathologist, molecular biologist and representatives of patients advocacy groups) of the SELNET consortium, and are conceived to provide the standard approach to diagnosis, treatment and follow-up of bone sarcoma patients in the Latin-American context.

Peritoneal malignancy: anatomy, pathophysiology and an update on modern day imaging

With increasing subspecialised experience in radical cytoreductive surgery and intra-abdominal chemotherapy for peritoneal malignancy, outcomes have improved significantly in selected patients. The surgery and the treatment regimens are radical and therefore correct patient selection is critical. The radiologist plays a central role in this process by estimating, as precisely as possible, the pre-treatment disease burden. Because of the nature of the disease process, accurate staging is not an easy task. Tumour deposits may be very small and in locations where they are very difficult to detect. It must be acknowledged that no form of modern day imaging has the capability of detecting the smallest peritoneal nodules, which may only be visible to direct inspection or histopathological evaluation. Nonetheless, it behoves the radiologist to be as exact and precise as possible in the reporting of this disease process. This is both to select patients who are likely to benefit from radical treatment, and just as importantly, to identify patients who are unlikely to achieve adequate cytoreductive outcomes. In this review, we outline the patterns of spread of disease and the anatomic basis for this, as well as the essential aspects of reporting abdominal studies in this patient group. We provide an evidence-based update on the relative strengths and limitations of our available multimodality imaging techniques namely CT, MRI and positron emission tomography/CT.

The Role of FDG-PET and Whole-Body MRI in High Grade Bone Sarcomas With Particular Focus on Osteosarcoma

Sarcoma represents less than 2% of adult malignancies and about 15% to 20% of malignancies in children and adolescents/young adults. This neoplasm accounts for more than 80 different clinico-pathological entities with different clinical behavior; osteosarcoma and ewing sarcoma are the most frequent primary bone tumors. Because of the general poor prognosis, it is important to find out as many prognostic factors as possible to choose the best therapeutical approach and to correctly schedule the follow-up examinations. Third level imaging such as MRI and PET/CT are of utmost importance in the evaluation of sarcoma patients. The spine and bones in general are optimal sites to be evaluated with FDG PET/CT since the physiological background is low. The standardized uptake value (SUV max, a semiquantitave parameter) is used as a surrogate for proliferative cell rate, and the spatial heterogeneity of FDG distribution within the primary mass as a surrogate for malignancy. In several studies SUVmax was a predictive value for overall survival and progression-free survival. Whole-body MRI is a well-established technique for systemic, radiation-free evaluation, which is mostly applied in the oncological field. WB-MRI provides a combination of anatomical and functional sequences and is useful specifically in the evaluation of disease in organs with relatively high background activity such as the brain, liver, kidney, and spinal canal. These technologies provide accurate staging (also useful to drive the biopsy towards the most active foci in large heterogeneous masses), therapy assessment, relapse detection of local recurrence and distance metastasis but also prognostic indexes, in the context of whole body diagnostic procedures. This paper will provide an overview of the role and added value of PET/CT and WB-MRI in bone sarcomas particular focus on osteosarcoma. We also analyzed the role of the PET/CT and MRI for target delineation of radiation therapy and we and we will do an analysis of future prospects as new tracer non FDG.

Comparison of pre- and post-contrast-enhanced attenuation correction using a CAIPI-accelerated T1-weighted Dixon 3D-VIBE sequence in 68Ga-DOTATOC PET/MRI

OBJECTIVES

To investigate the influence of contrast agent administration on attenuation correction (AC) based on a CAIPIRINHA (CAIPI)-accelerated T1-weighted Dixon 3D-VIBE sequence in ⁶⁸Ga-DOTATOC PET/MRI.

MATERIAL AND METHODS

Fifty-one patients with neuroendocrine tumors underwent whole-body ⁶⁸Ga-DOTATOC PET/MRI for tumor staging. Two PET reconstructions were performed using AC-maps that were created using a high-resolution CAIPI-accelerated Dixon-VIBE sequence with an additional bone atlas and truncation correction using the HUGE (B0 homogenization using gradient enhancement) method before and after application of Gadolinium (Gd)-based contrast agent. Standardized uptake values (SUVs) of 21 volumes of interest (VOIs) were compared between in both PET data sets per patient. A student's t-test for paired samples was performed to test for potential differences between both AC-maps and both reconstructed PET data sets. Bonferroni correction was performed to prevent α-error accumulation, p < 0.0024 was considered to indicate statistical significance.

RESULTS

Significant quantitative differences between SUVmax were found in the perirenal fat (19.65 ± 48.03 %, p < 0.0001), in the axillary fat (17.46 ± 63.67 %, p < 0.0001) and in the dorsal subcutaneous fat on level of lumbar vertebral body L4 (10.26 ± 25.29 %, p < 0.0001). Significant differences were also evident in the lungs apical (5.80 ± 10.53 %, p < 0.0001), dorsal at the level of the pulmonary trunk (15.04 ± 19.09 %, p < 0.0001) and dorsal in the basal lung (51.27 ± 147.61 %, p < 0.0001).

CONCLUSION

The administration of (Gd)-contrast agents in this study has shown a considerable influence on the AC-maps in PET/MRI and, consequently impacted quantification in the reconstructed PET data. Therefore, dedicated PET/MRI staging protocols have to be adjusted so that AC-map acquisition is performed prior to contrast agent administration.

Nuclear Medicine and Molecular Imaging in Nodal Staging and Surveillance of Ocular Melanoma: Case Reports and Review of the Literature

Ocular melanoma (OM) is a rare noncutaneous malignancy and consists of 2 different subtypes based on the anatomic location in the eye: uveal melanoma and conjunctival melanoma. Like cutaneous melanoma, OM benefits from nuclear medicine and molecular imaging in nodal staging and clinical management. Through the illustration of 2 distinctive cases, we aim to demonstrate the complementary roles of standard lymphoscintigraphy, advanced SPECT/CT, ¹⁸F-FDG PET/CT, and ¹⁸F-FDG PET/MRI in accurate nodal staging and surveillance of OM. We also review the epidemiology, existing staging guidelines, and management of uveal melanoma and conjunctival melanoma.

Prospective Correlation of Prognostic Immunohistochemical Markers With SUV and ADC Derived From Dedicated Hybrid Breast 18F-FDG PET/MRI in Women With Newly Diagnosed Breast Cancer

PURPOSE

The aim of this study was to correlate prognostically relevant immunohistochemical parameters of breast cancer with simultaneously acquired SUVs and apparent diffusion coefficient (ADC) values derived from hybrid breast PET/MRI.

PATIENTS AND METHODS

Fifty-six women with newly diagnosed, therapy-naive, histologically proven breast cancer (mean age, 54.1 ± 12.0 years) underwent dedicated prone 18F-FDG breast PET/MRI. Diffusion-weighted imaging (b-values: 0, 500, 1000 s/mm2) was performed simultaneously with the PET acquisition. A region of interest encompassing the entire primary tumor on each patient's PET/MRI scan was used to determine the glucose metabolism represented by maximum and mean SUV as well as into corresponding ADC maps to assess tumor cellularity represented by mean and minimum ADC values. Histopathological tumor grading and prognostically relevant immunohistochemical markers, that is, Ki67, progesterone receptor, estrogen receptor, and human epidermal growth factor receptor 2 (HER2), were assessed. Pearson correlation coefficients were calculated to compare SUV and ADC values as well as the immunohistochemically markers and molecular subtype. For the comparison with the tumor grading, a Wilcoxon test was used.

RESULTS

A significant inverse correlation between SUV and ADC values derived from breast PET/MRI (r = -0.49 for SUVmean vs ADCmean; r = -0.43 for SUVmax vs ADCmin; both P's < 0.001) was found. Tumor grading and Ki67 both showed a positive correlation with SUVmean from breast PET/MRI (r = 0.37 and r = 0.32, P < 0.01). For immunohistochemical markers, HER2 showed an inverse correlation with ADC values from breast PET/MRI (r = -0.35, P < 0.01). Molecular subtypes significantly correlate with SUVmax and SUVmean (r = 0.52 and r = 0.42, both P's < 0.05). In addition, estrogen receptor expression showed an inverse correlation with SUVmax and SUVmean from breast PET/MRI (r = -0.45 and r = -0.42, P < 0.001).

CONCLUSIONS

The present data show a correlation between increased glucose metabolism, cellularity, tumor grading, estrogen and HER2 expression, as well as molecular subtype of breast cancer primaries. Hence, simultaneous 18F-FDG PET and diffusion-weighted imaging from hybrid breast PET/MRI may serve as a predictive tool for identifying high-risk breast cancer patients in initial staging and guide-targeted therapy.

Is there a connection between immunohistochemical markers and grading of lung cancer with apparent diffusion coefficient (ADC) and standardised uptake values (SUV) of hybrid 18F-FDG-PET/MRI?

INTRODUCTION

To correlate tumour grading and prognostic immunohistochemical markers of lung cancer with simultaneously acquired standardised uptake values (SUV) and apparent diffusion coefficient (ADC) derived from hybrid PET/MRI.

METHODS

In this retrospective study, 55 consecutive patients (mean age 62.5 ± 9.2 years) with therapy-naïve, histologically proven lung cancer were included. All patients underwent whole-body PET/MRI using 18F-flourdeoxyglucose (18F-FDG) as a radiotracer. Diffusion-weighted imaging of the chest (DWI, b-values: 0, 500, 1000 s/mm² ) was performed simultaneously with PET acquisition. Histopathological tumour grading was available in 43/55 patients. In 15/55 patients, immunohistochemical markers, that is, phospho-AKT Ser473 (pAKTS473), phosphorylated extracellular signal-regulated kinase (pERK), phosphatase and tensin homolog (PTEN), and human epidermal growth factor receptor 2 (erbB2) were available.

RESULTS

The average SUVmax, SUVmean, ADCmin and ADCmean in lung cancer primaries were 12.6 ± 5.9, 7.7 ± 4.6, 569.9 ± 96.1 s/mm² and 825.8 ± 93.2 s/mm² , respectively. We found a significant inverse correlation between the ADCmin and SUVmax (r = -0.58, P < 0.001) as well as between the ADCmin and SUVmean (r = -0.44, P < 0.001). Tumour grading showed a significant positive correlation with SUVmax and SUVmean (R = 0.34 and R = 0.31, both P < 0.05) and a significant inverse correlation with ADCmin and ADCmean (r = -0.30 and r = -0.40, both P < 0.05). In addition, erbB2 showed a significant inverse correlation with SUVmax and SUVmean (r = -0.50 and r = -0.49, both P < 0.05). The other immunohistochemical markers did not show any significant correlation.

CONCLUSION

18F-FDG-PET/MRI showed weak to moderate correlations between SUV, ADC, tumour grading and erbB2-expression of lung cancer. Hence, 18F-FDG-PET/MRI may, to some extent, offer complementary information to the histopathology of lung cancer, for the evaluation of tumour aggressiveness and treatment response.

Applications of PET-MRI in musculoskeletal disease

New integrated PET-MRI systems potentially provide a complete imaging modality for diagnosis and evaluation of musculoskeletal disease. MRI is able to provide excellent high-resolution morphologic information with multiple contrast mechanisms that has made it the imaging modality of choice in evaluation of many musculoskeletal disorders. PET offers incomparable abilities to provide quantitative information about molecular and physiologic changes that often precede structural and biochemical changes. In combination, hybrid PET-MRI can enhance imaging of musculoskeletal disorders through early detection of disease as well as improved diagnostic sensitivity and specificity. The purpose of this article is to review emerging applications of PET-MRI in musculoskeletal disease. Both clinical applications of malignant musculoskeletal disease as well as new opportunities to incorporate the molecular capabilities of nuclear imaging into studies of nononcologic musculoskeletal disease are discussed. Lastly, we discuss some of the technical considerations and challenges of PET-MRI as they specifically relate to musculoskeletal disease.

LEVEL OF EVIDENCE

5 TECHNICAL EFFICACY: Stage 3 J. Magn. Reson. Imaging 2018;48:27-47.

Impact of patient comfort on diagnostic image quality during PET/MR exam: A quantitative survey study for clinical workflow management

Background

PET/MR is transferring from a powerful scientific research tool to an imaging modality in clinical routine practice. Whole body PET/MR screening usually takes 30–50 minutes to finish, during which a few factors might induce patient discomfort and further cause degraded image quality. The aim of this report is to investigate the patients' perception of the imaging procedure and its correlation with image quality.

Methods

One hundred and twenty patients (63 males and 57 females, average age = 51.3 years, range 22–70 years) who had been diagnosed with cancer or had previous history of cancer were recruited and scanned with a simultaneous PET/MR system. A questionnaire was given to all patients retrospectively after the PET/MR scan, which has nine questions to assess patients' feeling of the scan on a Likert scale scoring system (1–5, 1 as most satisfied). All PET/MR images were also visually examined by two experts independently to evaluate the quality of the images. Six body locations were assessed and each location was evaluated also with a Likert scale scoring system (1–5, 5 as the best quality). Mann–Whitney U­test was used for statistical analysis to check if there is significant correlation between image quality and patient perceptions.

Results

With a total of 120 patients, 118 questionnaires were filled and returned for analysis. The patients’ characteristics were summarized in Table 4. The statistics of the patients’ perception in the questionnaire were illustrated in Tables 5–7. Statistical significant correlations were found between MR image quality and patients’ characteristics/perception.

Conclusion

Our results show that PET/MR scanning is generally safe and comfortable for most of the patients. Statistical analysis does not support the hypothesis that bad patient’s perception leads to degraded image quality.

Current concepts in advanced sinonasal mucosal melanoma: a single institution experience

PURPOSE

To present outcome measures of sinonasal mucosal melanoma (SMM) patients with particular focus on current radiological and therapeutic options, especially in the non-curative setting (immunotherapy).

METHODS

Retrospective study on SMM patients treated at our institution between January 1992 and December 2018.

RESULTS

FDG-PET/MRI has emerged as the new hybrid imaging modality, addressing the need for high local tissue contrast in the paranasal sinuses and the skull base, while allowing for whole-body staging in search for distant metastases, including the brain. Primary treatment protocols consisted of tumor resection in 30/34 patients (88%), palliative radiation therapy (RT) in 3/34 patients (9%) and best supportive care therapy in 1/34 patient (3%). Of all the initially operated patients, 25/30 patients (83%) received adjuvant RT. A total of 9/34 patients (26%) was treated with immunotherapy after the previous combined therapy. For patients treated in curative intention, we observed a 1-year overall survival (OS) of 60% (18/30 patients) and a 3-year OS of 40% (12/30 patients). For patients treated with immunotherapy, median progression-free survival (PFS) was 5 months (IQR 0-13.75), with a maximum PFS of 16 months (combination of nivolumab and ipilimumab). However, there was no difference in OS in patients treated with immunotherapy vs. no immunotherapy (log rank 0.99).

CONCLUSIONS

Sinonasal mucosal melanoma is a highly aggressive tumor, requiring multimodal therapy and developing a substantial incidence of distant metastases. The introduction of FDG-PET/MRI offers new possibilities in the radiological assessment of the tumor and immunotherapy has altered the management in the non-curative setting, resulting in a substantial progression-free survival in selected cases.

Primary Bone Tumor of the Spine-An Evolving Field: What a General Spine Surgeon Should Know

STUDY DESIGN

A narrative review of the literature.

OBJECTIVE

This article reviews the general principles of treatment and investigation for primary bone tumors of the spine. Furthermore, it explores the emerging alternatives.

METHODS

A review was performed using Medline, Embase, and Cochrane databases.

RESULTS

Primary bone tumors of the spine are rare entities that general spine surgeons may encounter only a few times in their career. The treatment algorithm of these complex tumors is filled with nuances and is evolving constantly. For these reasons, patients should be referred to experienced tertiary or quaternary centers who can offer a comprehensive multidisciplinary approach. For most malignant spinal bone tumors, surgery remains the cornerstone of treatment. Respecting oncologic principles has been associated with improved survival and decreased local recurrence in multiple settings. However, even in experienced centers, these surgeries carry a significant risk of adverse events and possible long-term neurologic impairment. The associated morbidity of these procedures and the challenges of local recurrence have encouraged professionals caring for these patients to explore alternatives or adjuncts to surgical treatment.

CONCLUSIONS

Over the past few years, several advances have occurred in medical oncology, radiation oncology and interventional radiology, changing the treatment paradigm for some tumors. Other advances still need to be refined before being applied in a clinical setting.

Advanced magnetic resonance imaging (MRI) of soft tissue tumors: techniques and applications

Imaging evaluation of soft tissue tumors is important for the diagnosis, staging, and follow-up. Magnetic resonance imaging (MRI) is the preferred imaging modality due to its multiplanarity and optimal tissue contrast resolution. However, standard morphological sequences are often not sufficient to characterize the exact nature of the lesion, addressing the patient to an invasive bioptic examination for the definitive diagnosis. The recent technological advances with the development of functional MRI modalities such as diffusion-weighted imaging, dynamic contrast-enhanced perfusion imaging, magnetic resonance spectroscopy, and diffusion tensor imaging with tractography have implemented the multiparametricity of MR to evaluate in a noninvasive manner the biochemical, structural, and metabolic features of tumor tissues. The purpose of this article is to review the state of the art of these advanced MRI techniques, with focus on their technique and clinical application.

Multiparametric Whole-body MRI with Diffusion-weighted Imaging and ADC Mapping for the Identification of Visceral and Osseous Metastases From Solid Tumors

RATIONALE AND OBJECTIVES

The purpose of this study was to investigate the use of multiparametric, whole-body, diffusion-weighted imaging (WB-DWI) and apparent diffusion coefficient (ADC) maps with T₂-weighted magnetic resonance imaging (MRI) at 3T for the detection and monitoring of metastatic disease in patients.

MATERIALS AND METHODS

Fifty-four participants (32 healthy subjects and 22 patients) were scanned with WB-DWI methods using a 3T MRI scanner. Axial, sagittal, or coronal fat-suppressed T₂-weighted (T₂WI), T₁-weighted (T₁WI), and DWI images were acquired. Total MRI acquisition and set-up time was approximately 45 minutes. Metastatic disease on MRI was confirmed based on T₂WI characteristics. The number of lesions was established on computed tomography (CT) or positron emission tomography (PET-CT). Whole-body ADC maps and T₂WI were constructed, and region-of-interests were drawn in normal and abnormal-appearing tissue for quantitative analysis. Statistical analysis was performed using a paired t tests and P < .05 was considered statistically significant.

RESULTS

There were 91 metastatic lesions detected from the CT or PET-CT with a missed recurrent lesion in the prostate. Multiparametric WB-MRI had excellent sensitivity (96%) for detection of metastatic lesions compared to CT. ADC map values and the ADC ratio in metastatic bone lesions were significantly increased (P < .05) compared to normal bone. In soft tissue, ADC map values and ratios in metastatic lesions were decreased compared to normal soft tissue.

CONCLUSION

We have demonstrated that multiparametric WB-MRI is feasible for oncologic staging to identify bony and visceral metastasis in breast, prostate, pancreatic, and colorectal cancers. WB-MRI can be tailored to fit the patient, such that an "individualized patient sequence" can be developed for a comprehensive evaluation for staging and response during treatment.

Applications of PET/CT and PET/MR Imaging in Primary Bone Malignancies

Primary bone malignancies are characterized with anatomic imaging. However, in recent years, there has been an increased interest in PET/computed tomography scanning and PET/MRI with fludeoxyglucose F 18 for evaluating and staging musculoskeletal neoplasms. These hybrid imaging modalities have shown promise largely owing to their high sensitivity, ability to perform more thorough staging, and ability to monitor treatment response. This article reviews the current role of PET/computed tomography scanning and PET/MRI in primary malignancies of bone, with an emphasis on imaging characteristics, clinical usefulness, and current limitations.

Prospective comparison of 18F-FDG PET/MRI and 18F-FDG PET/CT for thoracic staging of non-small cell lung cancer

OBJECTIVES

To compare the diagnostic performance of ¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT for primary and locoregional lymph node staging in non-small cell lung cancer (NSCLC).

METHODS

In this prospective study, a total of 84 patients (51 men, 33 women, mean age 62.5 ± 9.1 years) with histopathologically confirmed NSCLC underwent ¹⁸F-FDG PET/CT followed by ¹⁸F-FDG PET/MRI in a single injection protocol. Two readers independently assessed T and N staging in separate sessions according to the seventh edition of the American Joint Committee on Cancer staging manual for ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI, respectively. Histopathology as a reference standard was available for N staging in all 84 patients and for T staging in 39 patients. Differences in staging accuracy were assessed by McNemars chi² test. The maximum standardized uptake value (SUV_max) and longitudinal diameters of primary tumors were correlated using Pearson's coefficients.

RESULTS

T stage was categorized concordantly in ¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT in 38 of 39 (97.4%) patients. Herein, ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI correctly determined the T stage in 92.3 and 89.7% of patients, respectively. N stage was categorized concordantly in 83 of 84 patients (98.8%). ¹⁸F-FDG PET/CT correctly determined the N stage in 78 of 84 patients (92.9%), while ¹⁸F-FDG PET/MRI correctly determined the N stage in 77 of 84 patients (91.7%). Differences between ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI in T and N staging accuracy were not statistically significant (p > 0.5, each). Tumor size and SUV_max measurements derived from both imaging modalities exhibited excellent correlation (r = 0.963 and r = 0.901, respectively).

CONCLUSION

¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT show an equivalently high diagnostic performance for T and N staging in patients suffering from NSCLC.

Local and whole-body staging in patients with primary breast cancer: a comparison of one-step to two-step staging utilizing 18F-FDG-PET/MRI

OBJECTIVES

The purpose of this study was to compare the diagnostic value of a one-step to a two-step staging algorithm utilizing ¹⁸F-FDG PET/MRI in breast cancer patients.

METHODS

A total of 38 patients (37 females and one male, mean age 57 ± 10 years; range 31-78 years) with newly diagnosed, histopathologically proven breast cancer were prospectively enrolled in this trial. All PET/MRI examinations were assessed for local tumor burden and metastatic spread in two separate reading sessions: (1) One-step algorithm comprising supine whole-body ¹⁸F-FDG PET/MRI, and (2) Two-step algorithm comprising a dedicated prone ¹⁸F-FDG breast PET/MRI and supine whole-body ¹⁸F-FDG PET/MRI.

RESULTS

On a patient based analysis the two-step algorithm correctly identified 37 out of 38 patients with breast carcinoma (97%), while five patients were missed by the one-step ¹⁸F-FDG PET/MRI algorithm (33/38; 87% correct identification). On a lesion-based analysis 56 breast cancer lesions were detected in the two-step algorithm and 44 breast cancer lesions could be correctly identified in the one-step ¹⁸F-FDG PET/MRI (79%), resulting in statistically significant differences between the two algorithms (p = 0.0015). For axillary lymph node evaluation sensitivity, specificity and accuracy was 93%, 95 and 94%, respectively. Furthermore, distant metastases could be detected in seven patients in both algorithms.

CONCLUSION

The results demonstrate the necessity and superiority of a two-step ¹⁸F-FDG PET/MRI algorithm, comprising dedicated prone breast imaging and supine whole-body imaging, when compared to the one-step algorithm for local and whole-body staging in breast cancer patients.

Simultaneous Preclinical Positron Emission Tomography-Magnetic Resonance Imaging Study of Lymphatic Drainage of Chelator-Free 64Cu-Labeled Nanoparticles

BACKGROUND

Hybrid positron emission tomography (PET)-magnetic resonance imaging (MRI) systems have been taken in use as new clinical diagnostic tools including detection and therapy planning of cancer. To reduce the amount of contrast agents injected in patients while fully benefitting both modalities, dual-modality probes are required.

MATERIAL AND METHODS

This study was first aimed at developing a hybrid PET-MRI probe by labeling superparamagnetic iron oxide nanoparticles (SPIONs) with ⁶⁴Cu using a fast and chelator-free conjugation method, and second, to demonstrate the ability of the agent to target sentinel lymph nodes (SLNs) in vivo using simultaneous PET-MRI imaging.

RESULTS

High labeling efficiency of 97% produced within 10-15 min was demonstrated at room temperature. ⁶⁴Cu-SPIONs were chemically stable in mouse serum for 24 h and after intradermal injection in the hind paw of C57BL/6J mice, demonstrated specific accumulation in the SLN. Simultaneous PET-MRI clearly demonstrated visualization of ⁶⁴Cu-SPIONs, in dynamic and static imaging sequences up to 24 h after administration.

CONCLUSION

The use of a single hybrid probe and simultaneous hybrid imaging provides an efficient, complementary integration of quantitation and is expected to improve preoperative planning and intraoperative guidance of cancer treatments.

Clinical PET/MRI: 2018 Update

OBJECTIVE

The purpose of this article is to provide an update on clinical PET/MRI, including current and developing clinical indications and technical developments.

CONCLUSION

PET/MRI is evolving rapidly, transitioning from a predominant research focus to exciting clinical practice. Key technical obstacles have been overcome, and further technical advances promise to herald significant advancements in image quality. Further optimization of protocols to address challenges posed by this hybrid modality will ensure the long-term success of PET/MRI.

Melanoma & nuclear medicine: new insights & advances

The contribution of nuclear medicine to management of melanoma patients is increasing. In intermediate-thickness N0 melanomas, lymphoscintigraphy provides a roadmap for sentinel node biopsy. With the introduction of single-photon emission computed tomography images with integrated computed tomography (SPECT/CT), 3D anatomic environments for accurate surgical planning are now possible. Sentinel node identification in intricate anatomical areas (pelvic cavity, head/neck) has been improved using hybrid radioactive/fluorescent tracers, preoperative lymphoscintigraphy and SPECT/CT together with modern intraoperative portable imaging technologies for surgical navigation (free-hand SPECT, portable gamma cameras). Furthermore, PET/CT today provides 3D roadmaps to resect 18F-fluorodeoxyglucose-avid melanoma lesions. Simultaneously, in advanced-stage melanoma and recurrences, 18F-fluorodeoxyglucose-PET/CT is useful in clinical staging and treatment decision as well as in the evaluation of therapy response. In this article, we review new insights and recent nuclear medicine advances in the management of melanoma patients.

Diagnosis of non-osseous spinal metastatic disease: the role of PET/CT and PET/MRI

The spine is the third most common site for distant metastasis in cancer patients with approximately 70% of patients with metastatic cancer having spinal involvement. Positron emission tomography (PET), combined with computed tomography (CT) or magnetic resonance imaging (MRI), has been deeply integrated in modern clinical oncology as a pivotal component of the diagnostic work-up of patients with cancer. PET is able to diagnose several neoplastic processes before any detectable morphological changes can be identified by anatomic imaging modalities alone. In this review, we discuss the role of PET/CT and PET/MRI in the diagnostic management of non-osseous metastatic disease of the spinal canal. While sometimes subtle, recognizing such disease on FDG PET/CT and PET/MRI imaging done routinely in cancer patients can guide treatment strategies to potentially prevent irreversible neurological damage.

Semiquantitative Assessment of 18F-FDG Uptake in the Normal Skeleton: Comparison Between PET/CT and Time-of-Flight Simultaneous PET/MRI

OBJECTIVE

Differences in the attenuation correction methods used in PET/CT scanners versus the newly introduced whole-body simultaneous PET/MRI reportedly result in differences in standardized uptake values (SUVs) in the normal skeleton. The aim of the study was to compare the semiquantitative FDG uptake in the normal skeleton using time-of-flight (TOF) PET/MRI versus PET/CT with and without TOF.

SUBJECTS AND METHODS

Participants received a single FDG injection and underwent non-TOF and TOF PET/CT (n = 23) or non-TOF PET/CT and TOF PET/MRI (n = 50). Mean SUV (SUV_mean) and maximum SUV (SUV_max) were measured from all PET scans for nine normal regions of the skeleton. Pearson correlation coefficients (r) were used to evaluate the SUV_max and SUV_mean of normal skeleton between non-TOF and TOF PET/CT, as well as between non-TOF PET/CT and TOF PET/MRI. In addition, percentage differences in SUV_max and SUV_mean of the normal skeleton between non-TOF and TOF PET/CT and between non-TOF PET/CT and TOF PET/MRI were evaluated.

RESULTS

The SUV_max and SUV_mean in the normal skeleton significantly increased between non-TOF and TOF PET/CT, but they significantly decreased between non-TOF PET/CT and TOF PET/MRI. The SUV_max and SUV_mean in normal skeleton showed good correlation between non-TOF PET/CT and TOF PET/MRI (SUV_max, r = 0.88; SUV_mean, r = 0.91) and showed a similar trend between non-TOF and TOF PET/CT (SUV_max, r = 0.88; SUV_mean, r = 0.94).

CONCLUSION

In the normal skeleton, SUV_max and SUV_mean showed high correlations between PET/MRI and PET/CT. The MRI attenuation correction used in TOF PET/MRI provides reliable semiquantitative measurements in the normal skeleton.

18 F-FDG PET/MR imaging in patients with suspected liver lesions: Value of liver-specific contrast agent Gadobenate dimeglumine

OBJECTIVES

To evaluate the added value of the application of the liver-specific contrast phase of Gadobenate dimeglumine (Gd-BOPTA) for detection and characterization of liver lesions in 18F-FDG PET/MRI.

METHODS

41 patients with histologically confirmed solid tumors and known / suspected liver metastases or not classifiable lesions in 18F-FDG PET/CT were included in this study. All patients underwent a subsequent Gd-BOPTA enhanced 18F-FDG PET/MRI examination. MRI without liver-specific contrast phase (MRI1), MRI with liver-specific contrast phase (MRI2), 18F-FDG PET/MRI without liver-specific contrast phase (PET/MRI1) and with liver-specific contrast phase (PET/MRI2) were separately evaluated for suspect lesions regarding lesion dignity, characterization, conspicuity and confidence.

RESULTS

PET/MRI datasets enabled correct identification of 18/18 patients with malignant lesions; MRI datasets correctly identified 17/18 patients. On a lesion-based analysis PET/MRI2 provided highest accuracy for differentiation of lesions into malignant and benign lesions of 98% and 100%. Respective values were 95% and 100% for PET/MRI1, 93% and 96% for MRI2 and 91% and 93% for MRI1. Statistically significant higher diagnostic confidence was found for PET/MRI2 and MRI2 datasets compared to PET/MRI1 and MRI1, respectively (p < 0.001).

CONCLUSION

The application of the liver-specific contrast phase in 18F-FDG PET/MRI further increases the diagnostic accuracy and diagnostic confidence for correct assessment of benign and malignant liver lesions.

Accuracy of Whole-Body DWI for Metastases Screening in a Diverse Group of Malignancies: Comparison With Conventional Cross-Sectional Imaging and Nuclear Scintigraphy

OBJECTIVE

The purpose of this study is to assess the role of whole-body (WB) DWI as a screening modality for the detection of metastases and to compare it to conventional cross-sectional imaging modalities or nuclear scintigraphy in a population with various histopathologic malignancies.

SUBJECTS AND METHODS

WB DWI and conventional imaging (CT, MRI, or scintigraphy) were performed for patients with known malignancies for metastatic workup, and these patients were followed up for a period of 1 year. Two radiologists assessed WB DW images separately, and conventional images were assessed by the senior radiologist. The metastatic lesions were classified into four regions: liver, lung, skeletal system, and lymph nodes. The reference standard was considered on the basis of histopathologic confirmation or clinical follow-up of the metastatic lesions.

RESULTS

WB DWI was slightly inferior to conventional imaging modalities for the detection of hepatic metastases (sensitivity, 86.6% vs 93.3%; specificity, 91.6% vs 95.8%; and accuracy, 89.7% vs 94.8%) and skeletal metastases (sensitivity, 81.8% vs 89.4%; specificity, 86.4% vs 94.3%; and accuracy, 85.2% vs 93.0%); however, the differences were not statistically significant (p = 0.625 for hepatic metastases and p = 0.0953 for skeletal metastases, McNemar test). WB DWI was statistically significantly inferior to conventional imaging for the detection of lymph node metastases (sensitivity, 74.0% vs 81.5%; specificity, 87.9% vs 90.1%; accuracy, 81.4% vs 86.0%; p = 0.0389). WB DWI was statistically significantly inferior to conventional imaging for the detection of pulmonary metastases (sensitivity, 33.3% vs 100.0%; specificity, 90.9% vs 100.0%; accuracy, 60.8% vs 100.0%; p = 0.045).

CONCLUSION

WB DWI can be used for screening hepatic and skeletal metastases, but its reliability as the sole imaging sequence for the detection of lymph nodal and pulmonary metastases is poor and, at present, it cannot replace conventional imaging modalities.

Staging performance of whole-body DWI, PET/CT and PET/MRI in invasive ductal carcinoma of the breast

The aim of the present study was to evaluate the performance of whole-body diffusion-weighted imaging (WB-DWI), whole-body positron emission tomography with computed tomography (WB-PET/CT), and whole-body positron emission tomography with magnetic resonance imaging (WB-PET/MRI) in staging patients with untreated invasive ductal carcinoma of the breast. Fifty-one women with newly diagnosed invasive ductal carcinoma of the breast underwent WB-DWI, WB-PET/CT and WB-PET/MRI before treatment. A radiologist and a nuclear medicine physician reviewed in consensus the images from the three modalities and searched for occurrence, number and location of metastases. Final staging, according to each technique, was compared. Pathology and imaging follow-up were used as the reference. WB-DWI, WB-PET/CT and WB-PET/MRI correctly and concordantly staged 33/51 patients: stage IIA in 7 patients, stage IIB in 8 patients, stage IIIC in 4 patients and stage IV in 14 patients. WB-DWI, WB-PET/CT and WB-PET/MRI incorrectly and concordantly staged 1/51 patient as stage IV instead of IIIA. Discordant staging was reported in 17/51 patients. WB-PET/MRI resulted in improved staging when compared to WB-PET/CT (50 correctly staged on WB-PET/MRI vs. 38 correctly staged on WB-PET/CT; McNemar's test; p<0.01). Comparing the performance of WB-PET/MRI and WB-DWI (43 correct) did not reveal a statistically significant difference (McNemar test, p=0.14). WB-PET/MRI is more accurate in the initial staging of breast cancer than WB-DWI and WB-PET/CT, however, the discrepancies between WB-PET/MRI and WB-DWI were not statistically significant. When available, WB-PET/MRI should be considered for staging patient with invasive ductal breast carcinoma.

Skeletal Scintigraphy

BACKGROUND

Skeletal scintigraphy remains a valuable tool in the initial and subsequent evaluation of the skeletal system in patients with a diagnosis of primary or metastatic neoplasms.

METHODS

We discuss radiopharmaceuticals, nuclear medicine imaging techniques, and current as well as future oncological applications in the adult population. Pertinent literature was reviewed to describe the advantages and limitations of available technologies for the evaluation of skeletal metastatic disease. Evaluation of primary and metastatic skeletal disease using nuclear medicine and positron emission tomography techniques is discussed.

RESULTS

Skeletal scintigraphy provides valuable information in the initial evaluation for the presence of osteoblastic skeletal metastases. Incremental advances on available radiopharmaceuticals (fludeoxyglucose F 18, sodium fluoride F 18), coupled with advances in imaging techniques and imaging devices (single photon emission computed tomography/computed tomography, positron emission tomography/computed tomography, positron emission tomography/magnetic resonance imaging), have had a significant impact on sensitivity, specificity, and accuracy rates for the detection of skeletal metastases.

CONCLUSIONS

Skeletal scintigraphy has a significant role in the initial diagnosis, staging, restaging, and treatment monitoring of patients with cancer and primary skeletal or metastatic disease. The coupling of diagnostic and therapeutic nuclear medicine agents in the setting of osteoblastic skeletal metastases is a valuable tool for the treatment for certain cancer types, including prostate cancer, and may become more widely used to treat other histologies as more data on other tumor types (eg, breast cancer, osteosarcoma) become available.

Conventional Modalities and Novel, Emerging Imaging Techniques for Musculoskeletal Tumors

BACKGROUND

Imaging of musculoskeletal tumors requires a multimodality approach and includes radiography, computed tomography (CT), and magnetic resonance imaging (MRI).

METHODS

Topics related to primary bone and soft-tissue tumors are reviewed. The fundamental imaging principles are discussed as well as the applications of emerging imaging modalities.

RESULTS

MRI is the preferred technique for the evaluation of musculoskeletal tumors, whereas other imaging modalities play a complementary role. Radiography is indicated as the first-line imaging modality in bone and soft-tissue tumors, whereas CT is the preferred modality for evaluating cortical osseous lesions or calcifications and in patients with contraindications to MRI. Positron emission tomography (PET)/CT and PET/MRI are helpful in identifying the glucose metabolism of the lesion. Ultrasonography is the most useful for biopsy guidance and can aid in differentiating cystic from solid masses and identifying vascularity. Novel modalities, such as diffusion-weighted imaging, spectroscopy, and habitat imaging, show promise in increasing diagnostic accuracy and affecting treatment strategies.

CONCLUSIONS

Conventional modalities and emerging, novel imaging techniques can provide noninvasive methods to diagnose and evaluate musculoskeletal tumors.

18F-FDG-PET/MRI in lymphoma patients

The introduction of hybrid PET/MRI imaging using integrated systems into clinical practice has opened up the possibility of reducing the radiation dose from hybrid imaging by eliminating the contribution from computed tomography. Studies comparing the possibilities of PET/CT and PET/MRI imaging demonstrated it is possible to use the advantages of the high contrast resolution of magnetic resonance for soft tissue and bone marrow along with PET records in a quality comparable to PET/CT imaging. The significant feature for PET imaging in Hodgkińs lymphoma is that it is a tissue with high levels of radiopharmaceutical accumulation, which decreases proportionally after successful therapeutic effect, the effect of therapy is assessed using Deauville score system on interim examinations. While the efficacy of prognosis determined using the Deauville scale in HL is widely accepted, it turns out that in DLBCL, the prognostic value of PET imaging is bound to the evaluation of subtypes. PET/MRI scanning can be used to evaluate a relapse if follicular lymphoma has already been treated, or to confirm transformation into more aggressive forms. In children and adults with Burkitt's lymphoma, negative findings after induction therapy have a high negative predictive value for relapse prognosis.

Targeted drug delivery of near IR fluorescent doxorubicin-conjugated poly(ethylene glycol) bisphosphonate nanoparticles for diagnosis and therapy of primary and metastatic bone cancer in a mouse model

BACKGROUND

Most primary and metastatic bone tumors demonstrate increased osteoclast activity and bone resorption. Current treatment is based on a combination of surgery, radiotherapy and chemotherapy. Severe side effects are associated with chemotherapy due to use of high dosage and nonspecific uptake. Bisphosphonates have a strong affinity to Ca2+ ions and are widely used in the treatment of bone disorders.

RESULTS

We have engineered a unique biodegradable bisphosphonate nanoparticle (NPs) bearing two functional surface groups: (1) primary amine groups for covalent attachment of a dye/drug (e.g. NIR dye Cy 7 or doxorubicin); (2) bisphosphonate groups for targeting and chelation to bone hydroxyapatite. In addition, these engineered NPs contain high polyethyleneglycol (PEG) concentration in order to increase their blood half life time. In vitro experiments on Saos-2 human osteosarcoma cell line, demonstrated that at a tenth of the concentration, doxorubicin-conjugated bisphosphonate NPs achieved a similar uptake to free doxorubicin. In vivo targeting experiments using the NIR fluorescence bisphosphonate NPs on both Soas-2 human osteosarcoma xenograft mouse model and orthotopic bone metastases mCherry-labeled 4T1 breast cancer mouse model confirmed specific targeting. In addition, therapeutic in vivo experiments using doxorubicin-conjugated bisphosphonate NPs demonstrated a 40% greater inhibition of tumor growth in Saos-2 human osteosarcoma xenograft mouse model when compared to free doxorubicin.

CONCLUSIONS

In this research we have shown the potential use of doxorubicin-conjugated BP NPs for the targeting and treatment of primary and metastatic bone tumors. The targeted delivery of doxorubicin to the tumor significantly increased the efficacy of the anti-cancer drug, thus enabling the effective use of a lower concentration of doxorubicin. Furthermore, the targeting ability of the BP NPs in an orthotopic xenograft mouse model reinforced our findings that these BP NPs have the potential to be used for the treatment of primary and metastatic bone cancer.

Evaluation of diagnostic performance of whole-body simultaneous PET/MRI in pediatric lymphoma

BACKGROUND

Whole-body (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is the standard of care for lymphoma. Simultaneous PET/MRI (magnetic resonance imaging) is a promising new modality that combines the metabolic information of PET with superior soft-tissue resolution and functional imaging capabilities of MRI while decreasing radiation dose. There is limited information on the clinical performance of PET/MRI in the pediatric setting.

OBJECTIVE

This study evaluated the feasibility, dosimetry, and qualitative and quantitative diagnostic performance of simultaneous whole-body FDG-PET/MRI in children with lymphoma compared to PET/CT.

MATERIALS AND METHODS

Children with lymphoma undergoing standard of care FDG-PET/CT were prospectively recruited for PET/MRI performed immediately after the PET/CT. Images were evaluated for quality, lesion detection and anatomical localization of FDG uptake. Maximum and mean standardized uptake values (SUVmax/mean) of normal organs and SUVmax of the most FDG-avid lesions were measured for PET/MRI and PET/CT. Estimation of radiation exposure was calculated using specific age-related factors.

RESULTS

Nine PET/MRI scans were performed in eight patients (mean age: 15.3 years). The mean time interval between PET/CT and PET/MRI was 51 ± 10 min. Both the PET/CT and PET/MRI exams had good image quality and alignment with complete (9/9) concordance in response assessment. The SUVs from PET/MRI and PET/CT were highly correlated for normal organs (SUVmean r(2): 0.88, P<0.0001) and very highly for FDG-avid lesions (SUVmax r(2): 0.94, P=0.0002). PET/MRI demonstrated an average percent radiation exposure reduction of 39% ± 13% compared with PET/CT.

CONCLUSION

Simultaneous whole-body PET/MRI is clinically feasible in pediatric lymphoma. PET/MRI performance is comparable to PET/CT for lesion detection and SUV measurements. Replacement of PET/CT with PET/MRI can significantly decrease radiation dose from diagnostic imaging in children.