Purpose
It has recently been recognized that PET/CT may play a role in diffuse parenchymal lung disease. However, interpretation can be confounded due to the variability in lung density both within ...and between individuals. To address this issue a novel correction method is proposed.
Methods
A CT scan acquired during shallow breathing is registered to a PET study and smoothed so as to match the PET resolution. This is used to derive voxel-based tissue fraction correction factors for the individual. The method was evaluated in a lung phantom study in which the lung was simulated by a Styrofoam/water mixture. The method was further evaluated using
18
F-FDG in 12 subjects free from pulmonary disease where ranges before and after correction were considered.
Results
Correction resulted in similar activity concentrations for the lung and background regions, consistent with the experimental phantom set-up. Correction resulted in reduced inter- and intrasubject variability in the estimated SUV. The possible application of the method was further demonstrated in five subjects with interstitial lung changes where increased SUV was demonstrated. Single study pre- and post-treatment studies were also analysed to further illustrate the utility of the method.
Conclusion
The proposed tissue fraction correction method is a promising technique to account for variability of density in interpreting lung PET studies.
IntroductionDynamic contrast-enhanced CT (DCE-CT) and positron emission tomography/CT (PET/CT) have a high reported accuracy for the diagnosis of malignancy in solitary pulmonary nodules (SPNs). The ...aim of this study was to compare the accuracy and cost-effectiveness of these.MethodsIn this prospective multicentre trial, 380 participants with an SPN (8–30 mm) and no recent history of malignancy underwent DCE-CT and PET/CT. All patients underwent either biopsy with histological diagnosis or completed CT follow-up. Primary outcome measures were sensitivity, specificity and overall diagnostic accuracy for PET/CT and DCE-CT. Costs and cost-effectiveness were estimated from a healthcare provider perspective using a decision-model.Results312 participants (47% female, 68.1±9.0 years) completed the study, with 61% rate of malignancy at 2 years. The sensitivity, specificity, positive predictive value and negative predictive values for DCE-CT were 95.3% (95% CI 91.3 to 97.5), 29.8% (95% CI 22.3 to 38.4), 68.2% (95% CI 62.4% to 73.5%) and 80.0% (95% CI 66.2 to 89.1), respectively, and for PET/CT were 79.1% (95% CI 72.7 to 84.2), 81.8% (95% CI 74.0 to 87.7), 87.3% (95% CI 81.5 to 91.5) and 71.2% (95% CI 63.2 to 78.1). The area under the receiver operator characteristic curve (AUROC) for DCE-CT and PET/CT was 0.62 (95% CI 0.58 to 0.67) and 0.80 (95% CI 0.76 to 0.85), respectively (p<0.001). Combined results significantly increased diagnostic accuracy over PET/CT alone (AUROC=0.90 (95% CI 0.86 to 0.93), p<0.001). DCE-CT was preferred when the willingness to pay per incremental cost per correctly treated malignancy was below £9000. Above £15 500 a combined approach was preferred.ConclusionsPET/CT has a superior diagnostic accuracy to DCE-CT for the diagnosis of SPNs. Combining both techniques improves the diagnostic accuracy over either test alone and could be cost-effective.Trial registration number NCT02013063
Radiomics allows information not readily available to the naked eye to be extracted from high resolution imaging modalities such as CT. Identifying that a cancer has already metastasised at the time ...of presentation through a radiomic signature will affect the treatment pathway. The ability to recognise the existence of metastases earlier will have a significant impact on the survival outcomes.
To create a novel radiomic signature using textural analysis in the evaluation of synchronous liver metastases in colorectal cancer.
CT images at baseline and subsequent surveillance over a 5-year period of patients with colorectal cancer were processed using textural analysis software. Comparison was made between those patients who developed liver metastases and those that remained disease free to detect differences in the ‘texture’ of the liver.
A total of 24 patients were divided into two matched groups for comparison. Significant differences between the two groups scores when using the textural analysis programme were found on coarse filtration (p = 0.044). Patients that went on to develop metastases an average of 18 months after presentation had higher levels of hepatic heterogeneity on CT.
This initial study demonstrates the potential of using a textural analysis programme to build a radiomic signature to predict the development of hepatic metastases in rectal cancer patients otherwise thought to have clear staging CT scans at time of presentation.
The major challenge in pre-surgical epileptic patient evaluation is the correct identification of the seizure onset area, especially in MR-negative patients. In this study, we aimed to: (1) assess ...the concordance between perfusion, from ASL, and metabolism, from (18)F-FDG, acquired simultaneously on PET/MR; (2) verify the utility of a statistical approach as supportive diagnostic tool for clinical readers. Secondarily, we compared (18)F-FDG PET data from the hybrid PET/MR system with those acquired with PET/CT, with the purpose of validate the reliability of (18)F-FDG PET/MR data. Twenty patients with refractory focal epilepsy, negative MR and a defined electro-clinical diagnosis underwent PET/MR, immediately followed by PET/CT. Standardized uptake value ratio (SUVr) and cerebral blood flow (CBF) maps were calculated for PET/CT-PET/MR and ASL, respectively. For all techniques, z-score of the asymmetry index (zAI) was applied for depicting significant Right/Left differences. SUVr and CBF images were firstly visually assessed by two neuroimaging readers, who then re-assessed them considering zAI for reaching a final diagnosis. High agreement between (18)F-FDG PET/MR and ASL was found, showing hypometabolism and hypoperfusion in the same hemisphere in 18/20 patients, while the remaining were normal. They were completely concordant in 14/18, concordant in at least one lobe in the remaining. zAI maps improved readers' confidence in 12/20 and 15/20 patients for (18)F-FDG PET/MR and ASL, respectively. (18)F-FDG PET/CT-PET/MR showed high agreement, especially when zAI was considered. The simultaneous metabolism-perfusion acquisition provides excellent concordance on focus lateralisation and good concordance on localisation, determining useful complementary information.
The role of positron emission tomography (PET) and PET/computed tomography (CT) in the assessment of a patient presenting with cancer of the pancreas is discussed in the overall context of the ...management of this condition. The clinical limitations persist, with many patients presenting late with unresectable disease and poor prospects for novel drug therapies. PET and PET/CT are best at diagnosing and staging but are relatively inefficient in the detection of nodal disease. The detection of late disease manifestations such as metastatic spread is often of little clinical consequence. PET/CT may be considered as a first-line imaging investigation but evidence for this approach needs to accrue. Overall detection sensitivity at diagnosis varies between 90% and 95% and specificity from 82% to 100%, whereas for staging, sensitivity data vary from 61% to 100% and specificity data from 67% to 100%.
Subsolid pulmonary nodules (SSNs) are frequent findings on CT scans, and their reported prevalence ranges between 9 and 20% in the literature. The management of SSNs requires specific knowledge. In ...this review, we report the standard imaging approach and the potential role of positron emission tomography/computed tomography (PET/CT) in the detection of pulmonary SSNs, to help clinicians by providing evidence-based recommendations. The classification of the basic histology, nomenclature, and behaviours of the different lesions is described, with the typical imaging patterns and main recommendations for their management when detected on CT imaging. A comprehensive review of the literature has been performed to determine the potential role of
18
F-fluorodeoxyglucose (
18
F-FDG) PET/CT in the evaluation of SSNs. Finally, we describe the synergy of CT and
18
F-FDG PET in the evaluation and management of SSNs. We hypothesise that in cases of
18
F-FDG-positive findings, it would be worth considering pre-emptive local treatment with ablation, radiotherapy, or surgical resection. New prospective studies with greater homogeneity of data acquisition, including imaging time points, would be beneficial when reappraising the role of
18
F-FDG PET/CT following new technical developments.
Purpose
To assess the diagnostic performance of PET/MR in patients with non-small-cell lung cancer.
Methods
Fifty consecutive consenting patients who underwent routine
18
F-FDG PET/CT for potentially ...radically treatable lung cancer following a staging CT scan were recruited for PET/MR imaging on the same day. Two experienced readers, unaware of the results with the other modalities, interpreted the PET/MR images independently. Discordances were resolved in consensus. PET/MR TNM staging was compared to surgical staging from thoracotomy as the reference standard in 33 patients. In the remaining 17 nonsurgical patients, TNM was determined based on histology from biopsy, imaging results (CT and PET/CT) and follow-up. ROC curve analysis was used to assess accuracy, sensitivity and specificity of the PET/MR in assessing the surgical resectability of primary tumour. The kappa statistic was used to assess interobserver agreement in the PET/MR TNM staging. Two different readers, without knowledge of the PET/MR findings, subsequently separately reviewed the PET/CT images for TNM staging. The generalized kappa statistic was used to determine intermodality agreement between PET/CT and PET/MR for TNM staging.
Results
ROC curve analysis showed that PET/MR had a specificity of 92.3 % and a sensitivity of 97.3 % in the determination of resectability with an AUC of 0.95. Interobserver agreement in PET/MR reading ranged from substantial to perfect between the two readers (Cohen’s kappa 0.646 – 1) for T stage, N stage and M stage. Intermodality agreement between PET/CT and PET/MR ranged from substantial to almost perfect for T stage, N stage and M stage (Cohen’s kappa 0.627 – 0.823).
Conclusion
In lung cancer patients PET/MR appears to be a robust technique for preoperative staging.
Introduction
To investigate the combined performance of quantitative CT (qCT) following a computer algorithm analysis (IMBIO) and
18
F-FDG PET/CT to assess survival in patients with idiopathic ...pulmonary fibrosis (IPF).
Methods
A total of 113 IPF patients (age 70 ± 9 years) prospectively and consecutively underwent
18
F-FDG PET/CT and high-resolution CT (HRCT) at our institution. During a mean follow-up of 29.6 ± 26 months, 44 (48%) patients died. As part of the qCT analysis, pattern evaluation of HRCT (using IMBIO software) included the total extent (percentage) of the following features: normal-appearing lung, hyperlucent lung, parenchymal damage (comprising ground-glass opacification, reticular pattern and honeycombing), and the pulmonary vessels. The maximum (SUV
max
) and minimum (SUV
min
) standardized uptake value (SUV) for
18
F-FDG uptake in the lungs, and the target-to-background (SUV
max
/SUV
min
) ratio (TBR) were quantified using routine region-of-interest (ROI) analysis. Pulmonary functional tests (PFTs) were acquired within 14 days of the PET/CT/HRCT scan. Kaplan–Meier (KM) survival analysis was used to identify associations with mortality.
Results
Data from 91 patients were available for comparative analysis. The average ± SD GAP gender, age, physiology score was 4.2 ± 1.7 (range 0–8). The average ± SD SUV
max
, SUV
min
, and TBR were 3.4 ± 1.4, 0.7 ± 0.2, and 5.6 ± 2.8, respectively. In all patients, qCT analysis demonstrated a predominantly reticular lung pattern (14.9 ± 12.4%). KM analysis showed that TBR (
p
= 0.018) and parenchymal damage assessed by qCT (
p
= 0.0002) were the best predictors of survival. Adding TBR and qCT to the GAP score significantly increased the ability to differentiate between high and low risk (
p
< 0.0001).
Conclusion
18
F-FDG PET and qCT are independent and synergistic in predicting mortality in patients with IPF.
Purpose
There is a lack of prognostic biomarkers in idiopathic pulmonary fibrosis (IPF) patients. The objective of this study is to investigate the potential of
18
F-FDG-PET/ CT to predict mortality ...in IPF.
Methods
A total of 113 IPF patients (93 males, 20 females, mean age ± SD: 70 ± 9 years) were prospectively recruited for
18
F-FDG-PET/CT. The overall maximum pulmonary uptake of
18
F-FDG (SUV
max
), the minimum pulmonary uptake or background lung activity (SUV
min
), and target-to-background (SUV
max
/ SUV
min
) ratio (TBR) were quantified using routine region-of-interest analysis. Kaplan–Meier analysis was used to identify associations of PET measurements with mortality. We also compared PET associations with IPF mortality with the established GAP (gender age and physiology) scoring system. Cox analysis assessed the independence of the significant PET measurement(s) from GAP score. We investigated synergisms between pulmonary
18
F-FDG-PET measurements and GAP score for risk stratification in IPF patients.
Results
During a mean follow-up of 29 months, there were 54 deaths. The mean TBR ± SD was 5.6 ± 2.7. Mortality was associated with high pulmonary TBR (
p
= 0.009), low forced vital capacity (FVC;
p
= 0.001), low transfer factor (TLCO;
p
< 0.001), high GAP index (
p
= 0.003), and high GAP stage (
p
= 0.003). Stepwise forward-Wald–Cox analysis revealed that the pulmonary TBR was independent of GAP classification (
p
= 0.010). The median survival in IPF patients with a TBR < 4.9 was 71 months, whilst in those with TBR > 4.9 was 24 months. Combining PET data with GAP data (“PET modified GAP score”) refined the ability to predict mortality.
Conclusions
A high pulmonary TBR is independently associated with increased risk of mortality in IPF patients.
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