The role of PET/CT in assessing pulmonary nodules in children with solid malignancies

Reducing pediatric total-body PET/CT imaging scan time with multimodal artificial intelligence technology

OBJECTIVES

This study aims to decrease the scan time and enhance image quality in pediatric total-body PET imaging by utilizing multimodal artificial intelligence techniques.

METHODS

A total of 270 pediatric patients who underwent total-body PET/CT scans with a uEXPLORER at the Sun Yat-sen University Cancer Center were retrospectively enrolled. 18F-fluorodeoxyglucose (18F-FDG) was administered at a dose of 3.7 MBq/kg with an acquisition time of 600 s. Short-term scan PET images (acquired within 6, 15, 30, 60 and 150 s) were obtained by truncating the list-mode data. A three-dimensional (3D) neural network was developed with a residual network as the basic structure, fusing low-dose CT images as prior information, which were fed to the network at different scales. The short-term PET images and low-dose CT images were processed by the multimodal 3D network to generate full-length, high-dose PET images. The nonlocal means method and the same 3D network without the fused CT information were used as reference methods. The performance of the network model was evaluated by quantitative and qualitative analyses.

RESULTS

Multimodal artificial intelligence techniques can significantly improve PET image quality. When fused with prior CT information, the anatomical information of the images was enhanced, and 60 s of scan data produced images of quality comparable to that of the full-time data.

CONCLUSION

Multimodal artificial intelligence techniques can effectively improve the quality of pediatric total-body PET/CT images acquired using ultrashort scan times. This has the potential to decrease the use of sedation, enhance guardian confidence, and reduce the probability of motion artifacts.

SPECT/CT, PET/CT and PET/MRI: oncologic and infectious applications and protocol considerations

Functional imaging is playing an increasingly important role in pediatric radiology. Hybrid imaging techniques utilizing PET/CT (positron emission tomography/computed tomography), PET/MRI (positron emission tomography/magnetic resonance imaging), or SPECT/CT (single photon emission computed tomography/computed tomography) are now available in nearly every clinical practice. There are an increasing number of indications for the use of functional imaging, including oncologic and infectious indications, and it is essential to select and design the hybrid imaging protocol in order to optimize both the functional and anatomic components of the examination. Optimizing the protocol includes strategies for dose reduction, judicious use of contrast media and diagnostic quality imaging as appropriate, and for the greatest reduction in exposure to ionizing radiation, utilizing PET/MRI, whenever available. This review will provide an overview of hybrid imaging protocol considerations with a focus on oncologic and infectious indications.

Imaging of pediatric extragonadal pelvic soft tissue tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

The most common pediatric extragonadal pelvic cancers include germ cell tumors, sacrococcygeal teratomas, and rhabdomyosarcomas (arising from the urinary bladder, prostate, paratesticular tissues, vagina, uterus, and perineum). This paper describes the radiological and nuclear medicine features of these entities and provides consensus-based recommendations for the assessment at diagnosis, during, and after treatment.

Imaging of pediatric extremity soft tissue tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Pediatric soft tissue tumors of the extremity include rhabdomyosarcoma and nonrhabdomyosarcoma neoplasms. This manuscript provides consensus-based imaging recommendations for imaging evaluation at diagnosis, during treatment, and following completion of therapy for patients with a soft tissue tumor of the extremity.

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.

The impact of reconstruction techniques on observer performance for the detection and characterization of small pulmonary nodules in chest CT of children under 13 years

OBJECTIVE

To compare three different reconstruction techniques of CT data for the detection of pulmonary nodules in children under 13 years. Secondly to assess the prevalence of perifissural nodular opacities.

MATERIALS AND METHODS

The study consisted of chest CTs of 31 children (median age 6.9 years, range 2.1-12.7), of whom 17 had known extra-thoracic malignancies. Four observers assessed three techniques for the presence of nodules: axial 5 mm maximum intensity projections (MIPs) used in conjunction with 1 mm slices (mode A), 1 mm slices alone (mode B) and 3 mm slices (mode C). All modes were available in 3D. Per mode sensitivities were determined above a certain threshold of reader agreement. Confidence level and reader agreement for identification of an opacity as nodule served as surrogate for quality of nodule characterization.

RESULTS

103 nodules (median size 2.0 mm) were detected. Mode A yielded the highest interreader agreement (κ 0.336) and a superior sensitivity (71%, p = 0.003) compared to mode B and C (κ 0.218, sensitivity 57% and κ 0.247, sensitivity 56%, respectively). Mode B provided the highest confidence level and interreader agreement with respect to nodule identification (mean 4.3/5, κw 0.508). Double reading improved and evened interreader agreement for all modes (κ 0.450), mode A maintained the highest sensitivity (89.1%, p = 0.05-0.08). A median of 1 intrapulmonary lymph node/patient was seen in children with and without malignancy.

CONCLUSION

MIP improves the detection of pulmonary nodules in chest CTs of children, but overall interreader agreement is only fair. Double reading represents a powerful tool to increase diagnostic reliability in chest CTs of children with a malignancy. Nodule characterization is best with 1 mm slices. Intrapulmonary lymph nodes occur in children with and without malignancy.

Considerations in the Diagnosis and Management of Pediatric Patients With Favorable Histology Wilms Tumor Who Present With Only Pulmonary Nodules

More than 70% of children with stage IV, favorable histology (FH) Wilms tumor will be relapse-free survivors 16 years after diagnosis. Successful treatment generally includes whole lung radiation therapy and doxorubicin. Such therapy is associated with adverse, long-term effects, including impaired pulmonary function, congestive heart failure, and second malignant neoplasms, especially breast cancer. Cooperative groups have adopted a risk-based approach to the treatment of these patients. It is important to recall the good overall prognosis for this group before recommendations for intensification are made based on preliminary data and in the absence of histological confirmation of persistent malignant disease.

Clinical significance of pulmonary nodules detected on abdominal CT in pediatric patients

BACKGROUND

The clinical significance of a pulmonary nodule that is detected incidentally on CT studies in children is unknown. In addition, there is limited information regarding the management of incidentally detected pulmonary nodules discovered on abdominal CT studies in children.

OBJECTIVE

The purpose of this study was to investigate the clinical significance of incidental pulmonary nodules detected on abdominal CT studies in children.

MATERIALS AND METHODS

This was a retrospective study performed following institutional review board approval. Abdominal CT reports in patients younger than 18 years of age from July 2004 to June 2011 were reviewed for the terms "nodule," "nodular" or "mass" in reference to the lung bases. The study population included those pediatric patients in whom pulmonary nodules were initially detected on abdominal CT studies. The largest pulmonary nodules detected on CT studies were evaluated for their features (size, shape, margin, attenuation, location, and presence of calcification and cavitation). Follow-up CT studies and clinical records were reviewed for demographic information, history of underlying malignancies and the clinical outcome of the incidental pulmonary nodules. Comparison of malignant versus benign pulmonary nodules was performed with respect to the size of the nodule, imaging features on CT, and patient history of malignancy using the Student's t-test and Fisher exact test. Youden J-index in receiver operating characteristic (ROC) analysis was used to determine the optimal cut-off size for suggesting a high risk of malignancy of incidentally detected pulmonary nodules.

RESULTS

Pulmonary nodules meeting inclusion criteria were detected in 62 (1.2%) of 5,234 patients. The mean age of patients with nodules was 11.2 years (range: 5 months-18 years). Thirty-one patients (50%) had follow-up CT studies and two of these patients (6%) were subsequently found to have malignant pulmonary nodules. Both of these patients had a history of malignancy. Of the remaining 31 patients without follow-up CT studies, none had a history of malignancy. Clinical follow-up data was available in 26 of these 31 patients (84%) and none had any evidence of malignant pulmonary nodule development. There was a significant association between history of malignancy and incidentally detected pulmonary nodules on abdominal CT studies subsequently found to be malignant (P = 0.036). The size was significantly larger for the malignant pulmonary nodules compared to the benign pulmonary nodules with a size ≥7 mm in diameter being the optimal cut-off for suggesting a high risk of malignancy (11.5 ± 6.4 mm vs. 4.7 ± 3.0 mm, P = 0.003).

CONCLUSION

The incidence of pulmonary nodules found on pediatric abdominal CT studies is 1.2%. The incidence of malignancy in such pulmonary nodules is low (3%) and only seen in the setting of pulmonary nodules ≥7 mm in diameter in children with a history of malignancy. Therefore, further investigation is warranted for pulmonary nodules that are ≥7 mm in children with a history of malignancy while further imaging work-up may not be necessary in the remaining patients in this pediatric patient population.