Exploring ASL perfusion MRI as a substitutive modality for 18F-FDG PET in determining the laterality of mesial temporal lobe epilepsy

OBJECTIVE

The aim of this investigation was to determine whether a correlation could be discerned between perfusion acquired through ASL MRI and metabolic data acquired via 18F-fluorodeoxyglucose (18F-FDG) PET in mesial temporal lobe epilepsy (mTLE).

METHODS

ASL MRI and 18F-FDG PET data were gathered from 22 mTLE patients. Relative cerebral blood flow (rCBF) asymmetry index (AIs) were measured using ASL MRI, and standardized uptake value ratio (SUVr) maps were obtained from 18F-FDG PET, focusing on bilateral vascular territories and key bitemporal lobe structures (amygdala, hippocampus, and parahippocampus). Intra-group comparisons were carried out to detect hypoperfusion and hypometabolism between the left and right brain hemispheres for both rCBF and SUVr in right and left mTLE. Correlations between the two AIs computed for each modality were examined.

RESULTS

Significant correlations were observed between rCBF and SUVr AIs in the middle temporal gyrus, superior temporal gyrus, and hippocampus. Significant correlations were also found in vascular territories of the distal posterior, intermediate anterior, intermediate middle, proximal anterior, and proximal middle cerebral arteries. Intra-group comparisons unveiled significant differences in rCBF and SUVr between the left and right brain hemispheres for right mTLE, while hypoperfusion and hypometabolism were infrequently observed in any intracranial region for left mTLE.

CONCLUSION

The study's findings suggest promising concordance between hypometabolism estimated by 18F-FDG PET and hypoperfusion determined by ASL perfusion MRI. This raises the possibility that, with prospective technical enhancements, ASL perfusion MRI could be considered an alternative modality to 18F-FDG PET in the future.

18F-FDG PET/CT in left ventricular assist device infections: In-depth characterization and clinical implications

BACKGROUND

Previous retrospective studies suggest a good diagnostic performance of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET)/computed tomography (CT) in left ventricular assist device (LVAD) infections. Our aim was to prospectively evaluate the role of PET/CT in the characterization and impact on clinical management of LVAD infections.

METHODS

A total of 40 patients (aged 58 [53-62] years) with suspected LVAD infection and 5 controls (aged 69 [64-71] years) underwent 18F-FDG-PET/CT. Four LVAD components were evaluated: exit site and subcutaneous driveline (peripheral), pump pocket, and outflow graft. The location with maximal uptake was considered the presumed site of infection. Infection was confirmed by positive culture (exit site or blood) and/or surgical findings.

RESULTS

Visual uptake was present in 40 patients (100%) in the infection group vs 4 (80%) control subjects. For each individual component, the presence of uptake was more frequent in the infection than in the control group. The location of maximal uptake was most frequently the pump pocket (48%) in the infection group and the peripheral components (75%) in the control group. Maximum standard uptake values (SUVmax) were higher in the infection than in the control group: SUVmax (average all components): 6.9 (5.1-8.5) vs 3.8 (3.7-4.3), p = 0.002; SUVmax (location of maximal uptake): 10.6 ± 4.0 vs 5.4 ± 1.9, p = 0.01. Pump pocket infections were more frequent in patients with bacteremia than without bacteremia (79% vs 31%, p = 0.011). Pseudomonas (32%) and methicillin-susceptible Staphylococcus aureus (29%) were the most frequent pathogens and were associated with pump pocket infections, while Staphylococcus epidermis (11%) was associated with peripheral infections. PET/CT affected the clinical management of 83% of patients with infection, resulting in surgical debridement (8%), pump exchange (13%), and upgrade in the transplant listing status (10%), leading to 8% of urgent transplants.

CONCLUSIONS

18F-FDG-PET/CT enables the diagnosis and characterization of the extent of LVAD infections, which can significantly affect the clinical management of these patients.

Diagnostic value of 18F-fluorodeoxyglucose positron emission tomography and computed tomography for differentiating polymyalgia rheumatica and rheumatoid arthritis: Using classification and regression tree analysis

OBJECTIVES

Determining which sites were important to differentiate polymyalgia rheumatica (PMR) from rheumatoid arthritis (RA) using 18F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET-CT) is challenging.

METHODS

Patients with PMR or RA who were undergoing PET-CT were recruited at two mutual-aid hospitals in Japan between 2009 and 2018. Classification and regression tree (CART) analyses were performed to identify FDG uptake patterns that differentiated PMR from RA.

RESULTS

We enrolled 35 patients with PMR and 46 patients with RA. Univariate CART analysis showed that FDG uptake in the shoulder joints, spinous processes of the lumbar vertebrae, pubic symphysis, sternoclavicular joints, ischial tuberosities, greater trochanters, and hip joints differentiated PMR from RA. Multivariate CART analysis revealed that FDG uptake by at least one of the ischial tuberosities had the highest diagnostic value for distinguishing PMR from RA (sensitivity, 77.1%; specificity, 82.6%). We performed the same CART analysis to patients who had not undergone treatment (PMR, n = 28; RA, n = 9). Similar results were obtained, and sensitivity and specificity were increased (sensitivity, 89.3%; specificity, 88.8%).

CONCLUSIONS

In PET-CT, FDG uptake by at least one of the ischial tuberosities best discriminates between PMR and RA.

Potential Added Value of 18F-FDG PET Metabolic Parameters in Predicting Disease Relapse in Type 1 Autoimmune Pancreatitis

BACKGROUND

The predictive value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) metabolic parameters for predicting AIP relapse is currently unknown. This study firstly explored the value of 18F-FDG PET/CT parameters as predictors of type 1 AIP relapse.

METHODS

This multicenter retrospective cohort study analyzed 51 patients who received 18F-FDG PET/CT prior to treatment and did not receive maintenance therapy after remission. The study collected baseline characteristics and clinical data and conducted qualitative and semi-quantitative analysis of pancreatic lesions and extrapancreatic organs. The study used three thresholds to select the boundaries of pancreatic lesions to evaluate metabolic parameters, including the maximum standard uptake value (SUVmax), mean standard uptake value (SUVmean), total lesion glycolysis (TLG), metabolic tumor volume (MTV), and tumor-to-normal liver standard uptake value ratio (SUVR). Univariate and multivariate analyses were performed to identify independent predictors and build a recurrence prediction model. The model was internally validated using the bootstrap method and a nomogram was created for clinical application.

RESULTS

In the univariable analysis, the relapsed group showed higher levels of SUVmax (6.0 ± 1.6 vs. 5.2 ± 1.1; P = 0.047), SUVR (2.3 [2.0-3.0] vs. 2.0 [1.6-2.4]; P = 0.026), and TLG2.5 (234.5 ± 149.1 vs. 139.6 ± 102.5; P = 0.020) among the 18F-FDG PET metabolic parameters compared to the non-relapsed group. In the multivariable analysis, serum IgG4 (OR, 1.001; 95% CI, 1.000-1.002; P = 0.014) and TLG2.5 (OR, 1.007; 95% CI, 1.002-1.013; P = 0.012) were independent predictors associated with relapse of type 1 AIP. A receiver-operating characteristic curve of the predictive model with these two predictors demonstrated an area under the curve of 0.806.

CONCLUSION

18F-FDG PET/CT metabolic parameters, particularly TLG2.5, are potential predictors for relapse in patients with type 1 AIP. A multiparameter model that includes IgG4 and TLG2.5 can enhance the ability to predict AIP relapse.

Remission of Cardiac Sarcoidosis after the Administration of Methotrexate as First-line Drug Therapy

A 54-year-old woman developed new-onset heart failure and was diagnosed with cardiac sarcoidosis. An implantable cardioverter-defibrillator with biventricular pacing was implanted before immunosuppressive therapy to prevent sudden death. The patient refused oral steroids because she disliked their specific side effects and potential adverse events with long-term use; therefore, methotrexate was chosen as an alternative first-line drug. Nine months after starting oral therapy, 18F-fluorodeoxyglucose-positron emission tomography revealed remission of sarcoidosis, disappearance of heart failure symptoms, marked improvement in cardiac contractility, and a reduced frequency of ventricular arrhythmias.

The incremental value of myocardial viability, evaluated by 18F-fluorodeoxyglucose positron emission tomography, and cardiovascular magnetic resonance for mortality prediction in patients with previous myocardial infarction and symptomatic heart failure

OBJECTIVES

To find the imaging mortality predictors in patients with previous myocardial infarction (MI), symptomatic heart failure (HF), and reduced left ventricle (LV) ejection fraction (EF).

METHODS

for the study 39 patients were selected prospectively with prior MI, symptomatic HF, and LVEF ≤40%. All patients underwent transthoracic echocardiography (TTE), single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI), 18F-FDG positron emission tomography (FDG PET). 31 patients underwent cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE). Patients were divided into two groups: 1 group - cardiac death; 2 group - no cardiac death. Myocardial scars were assessed on a 5-point-scale. Follow-up data was obtained.

RESULTS

Imaging features disclosed significant difference (p < 0.05) of defect score (CMR and SPECT-PET), LV end-diastolic diameter (EDD) (TTE), LVEDD index (CMR), LV global longitudinal strain (CMR) and LV global circumferential strain (CMR) between the groups. Predictors of cardiac death were: LVEDD index (TTE) and LV global longitudinal strain. The cut-off values to predict cardiac death were: defect score (CMR) 25 (AUC, 79.5%; OR 1.8, 95% CI 1.2-2.7), SPECT-PET defect score 22 (AUC, 73.9%; OR 0.5, 95% CI 0.3-0.7), LVEDD (TTE) 58 mm (AUC, 88.4%; OR 23.6, 95% CI 2.6-217.7), LVEDDi 30 mm/m2 (TTE) (AUC, 73.6%; OR 22.0, 95% CI 1.9-251.5), LVEDDi 33.6 mm/m2 (CMR) (AUC, 73.6%; OR 22.0, 95% CI 1.9-251.5), LV global longitudinal strain -13.4 (AUC, 87.8%; OR 2.1, 95% CI 1.2-3.7) and LV global circumferential strain -16.3 (AUC, 76.1%; OR 1.9, 95% CI 1.2-3.0).

CONCLUSIONS

Imaging features, such as defect score (CMR) >25, SPECT-PET defect score >22, LVEDD (TTE) >58 mm, LVEDDi (TTE) >30 mm/m2, LVEDDi (CMR) >33.6 mm/m2, LV global longitudinal strain -13.4 and LV global circumferential strain -16.3, may increase sensitivity and specificity of FDG PET and LGE CMR predicting of late mortality.

Outcomes of solitary postoperative recurrence of esophageal squamous cell carcinoma diagnosed with FDG-PET/CT and treated with definitive radiation therapy

BACKGROUND

Surgical resection of esophageal cancer is frequently performed to achieve a complete cure. However, the postoperative recurrence rate is 36.8-42.5%, leading to poor prognosis. Radiation therapy has been used to treat recurrences; solitary recurrence has been proposed as a prognostic factor for radiation therapy, though its significance is unclear. ¹⁸F-fluorodeoxyglucose positron emission tomography is a highly accurate diagnostic modality for esophageal cancer. This retrospective study aimed to analyze the outcomes of solitary postoperative recurrences of esophageal squamous cell carcinoma diagnosed with ¹⁸F-fluorodeoxyglucose positron emission tomography and treated with definitive radiation therapy.

METHODS

We examined 27 patients who underwent definitive radiation therapy for single or multiple postoperative recurrences of esophageal squamous cell carcinoma between May 2015 and April 2021. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography was performed within 3 months before the commencement of radiation therapy. Kaplan-Meier, univariate, and multivariate analyses were performed to examine the overall survival and identify potential prognostic factors.

RESULTS

The 1-, 2-, and 3-year overall survival rates were 85.2%, 62.6%, and 47.3%, respectively, and solitary recurrence was the only significant factor associated with overall survival (P = 0.003). The 1-, 2-, and 3-year overall survival rates in patients with solitary recurrence were 91.7%, 80.2%, and 80.2%, respectively, and in patients with multiple recurrences they were 80.0%, 50.3%, and 25.1%, respectively. Multivariate analysis also showed solitary recurrence as a significant factor for overall survival.

CONCLUSIONS

When diagnosed with ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography, solitary recurrence appears to have a more favorable prognosis than multiple recurrences.

Which modality is better to diagnose high-grade transformation in retroperitoneal liposarcoma? Comparison of computed tomography, positron emission tomography, and magnetic resonance imaging

BACKGROUND

Survival in patients with retroperitoneal liposarcoma (RPLS) depends on the surgical management of the dedifferentiated foci. The present study investigated the diagnostic yield of contrast-enhanced CT, ¹⁸F-fluorodeoxyglucose positron emission tomography (PET), and diffusion-weighted MRI in terms of dedifferentiated foci within the RPLS.

METHODS

Patients treated with primary or recurrent RPLS who underwent the above imaging between January 2010 and December 2021 were retrospectively reviewed. The diagnostic accuracy of the three modalities for histologic subtype of dedifferentiated liposarcoma (DDLS) and French Federation of Cancer Center (FNCLCC) grade 2/3 were compared using receiver operating characteristic curves and areas under the curves (AUCs).

RESULTS

The cohort involved 32 patients with 53 tumors; 30 of which exhibited DDLS and 31 of which did FNCLCC grades 2/3. The optimal thresholds for predicting DDLS were mean CT value of 31 Hounsfield Unit (HU) (AUC = 0.880, 95% CI 0.775-0.984; p < 0.001), maximum standardized uptake value (SUVmax) of 2.9 (AUC = 0.865 95% CI 0.792-0.980; p < 0.001), while MRI failed to differentiate DDLS. The cutoff values for distinguishing FNCLCC grades 1 and 2/3 were a mean CT value of 24 HU (AUC = 0.858, 95% CI 0.731-0.985; p < 0.001) and SUVmax of 2.9 (AUC = 0.885, 95% CI 0.792-0.978; p < 0.001). MRI had no sufficient power to separate these grades.

CONCLUSIONS

Contrast-enhanced CT and PET were useful for predicting DDLS and FNCLCC grade 2/3, while MRI was inferior to these two modalities.

Regional cerebral hypometabolism on 18F-FDG PET/CT scan in delirium is independent of acute illness and dementia

INTRODUCTION

Delirium is associated with new onset dementia and accelerated cognitive decline; however, its pathophysiology remains unknown. Cerebral glucose metabolism previously seen in delirium may have been attributable to acute illness and/or dementia. We aimed to statistically map cerebral glucose metabolism attributable to delirium.

METHODS

We assessed cerebral glucose metabolism using ¹⁸ F-fluorodeoxyglucose positron emission tomography (FDG-PET) in sick, older patients with and without delirium, all without clinical dementia (N = 20). Strict exclusion criteria were adopted to minimize the effect of established confounders on FDG-PET.

RESULTS

Patients with delirium demonstrated hypometabolism in the bilateral thalami and right superior frontal, right posterior cingulate, right infero-lateral anterior temporal, and left superior parietal cortices. Regional hypometabolism correlated with delirium severity and performance on neuropsychological testing.

DISCUSSION

In patients with acute illness but without clinical dementia, delirium is accompanied by regional cerebral hypometabolism. While some hypometabolic regions may represent preclinical Alzheimer's disease (AD), thalamic hypometabolism is atypical of AD and consistent with the clinical features that are unique to delirium.

Comparison of Conventional Imaging and 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Diagnostic Accuracy of Staging in Patients with Intrahepatic Cholangiocarcinoma

We aimed to examine the accuracy of tumor staging of intrahepatic cholangiocarcinoma (ICC) by using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT). From January 2001 to December 2021, 202 patients underwent PET-CT, CT, and MRI for the initial staging of ICC in two institutions. Among them, 102 patients had undergone surgical treatment. Ninety patients who had a histopathological diagnosis of ICC were retrospectively reviewed. The sensitivity and specificity of 18F-FDG PET-CT, CT, and magnetic resonance imaging (MRI) in detecting tumors, satellite focus, vascular invasion, and lymph node metastases were analyzed. Ninety patients with histologically diagnosed ICC were included. PET-CT demonstrated no statistically significant advantage over CT and MR in the diagnosis of multiple tumors and macrovascular invasion, and bile duct invasion. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET-CT in lymph node metastases were 84%, 86%, 91%, 84%, and 86%, respectively. PET-CT revealed a significantly higher accuracy compared to CT or MRI (86%, 67%, and 76%, p < 0.01, respectively) in the diagnosis of regional lymph node metastases. The accuracy of tumor staging by PET-CT was higher than that by CT/MRI (PET-CT vs. CT vs. MRI: 68/90 vs. 47/90 vs. 51/90, p < 0.05). 18F-FDG PET-CT had sensitivity and specificity values for diagnosing satellite focus and vascular and bile duct invasion similar to those of CT or MRI; however, PET-CT showed higher accuracy in diagnosing regional lymph node metastases. 18F-FDG PET-CT exhibited higher tumor staging accuracy than that of CT/MRI. Thus, 18FDG PET-CT may support tumor staging in ICC.

Enhancement of 18F-Fluorodeoxyglucose PET Image Quality by Deep-Learning-Based Image Reconstruction Using Advanced Intelligent Clear-IQ Engine in Semiconductor-Based PET/CT Scanners

Deep learning (DL) image quality improvement has been studied for application to ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT). It is unclear, however, whether DL can increase the quality of images obtained with semiconductor-based PET/CT scanners. This study aimed to compare the quality of semiconductor-based PET/CT scanner images obtained by DL-based technology and conventional OSEM image with Gaussian postfilter. For DL-based data processing implementation, we used Advanced Intelligent Clear-IQ Engine (AiCE, Canon Medical Systems, Tochigi, Japan) and for OSEM images, Gaussian postfilter of 3 mm FWHM is used. Thirty patients who underwent semiconductor-based PET/CT scanner imaging between May 6, 2021, and May 19, 2021, were enrolled. We compared AiCE images and OSEM images and scored them for delineation, image noise, and overall image quality. We also measured standardized uptake values (SUVs) in tumors and healthy tissues and compared them between AiCE and OSEM. AiCE images scored significantly higher than OSEM images for delineation, image noise, and overall image quality. The Fleiss kappa value for the interobserver agreement was 0.57. Among the 21 SUV measurements in healthy organs, 11 (52.4%) measurements were significantly different between AiCE and OSEM images. More pathological lesions were detected in AiCE images as compared with OSEM images, with AiCE images showing higher SUVs for pathological lesions than OSEM images. AiCE can improve the quality of images acquired with semiconductor-based PET/CT scanners, including the noise level, contrast, and tumor detection capability.

Evaluation of Lung Glucose Uptake with Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/CT in Patients with Pulmonary Arterial Hypertension and Pulmonary Hypertension Due to Left Heart Disease

Aim: Previous studies have demonstrated increased glucose uptake by ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) in lung parenchyma in animal models or small pulmonary arterial hypertension (PAH) cohorts. However, it is not well known whether increased FDG uptake in the lung is a unique phenomenon in PAH or whether elevated pulmonary artery pressure (PAP) induces FDG uptake. Methods and results: Nineteen patients with PAH, 8 patients with pulmonary hypertension due to left heart disease (PH-LHD), and 14 age matched control subjects were included. All PH patients underwent right heart catheterization and FDG-PET. The mean standard uptake value (SUV g/mL) of FDG in each lung was obtained and average values of both lungs were calculated as mean lung FDG SUV. The correlation between hemodynamics and mean lung FDG SUV was also analyzed in PH patients. Mean PAP (mPAP) was not significantly different between PAH and PH-LHD (45±11 vs 43±5 mmHg, p=0.51). PAH patients demonstrated significantly increased mean lung FDG SUV compared with PH-LHD and controls (PAH: 0.76±0.26 vs PH-LHD: 0.51±0.12 vs controls: 0.53±0.16, p=0.0025). The mean lung FDG SUV did not correlate with mPAP either in PAH or PH-LHD. Conclusion: PAH is associated with increased lung FDG uptake indicating increased glucose utilization in the lung. This may represent metabolic shift to glycolysis and/or active inflammation in the remodeled pulmonary vasculature, and is observed to a greater extent in PAH than in patients with PH secondary to LHD and control subjects without PH.

Relationship Between 18F-fluorodeoxyglucose Uptake on Positron Emission Tomography and Aortic Calcification

Introduction: Although ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) has been widely utilized to assess the extent of inflammation, the association between the extent and severity of atherosclerosis and ¹⁸F-FDG uptake on PET remains unexamined. The current study aimed to investigate whether aortic calcium (AC) scores were associated with increased aortic uptake of ¹⁸F-FDG on PET. Methods: A total of 167 consecutive patients with suspected lung cancer but unproven malignancy who underwent non-contrast-enhanced computed tomography (CT) and ¹⁸F-FDG PET/CT were enrolled. The average standardized uptake values in the ascending aorta were used to calculate the target-to-background ratio (Mean TBR). The total (thoracic and abdominal) AC scores were measured on non-contrast-enhanced chest and abdominal CT using the Agatston method, and were categorized into three groups (0, 1-399, and ≥400). The relationship between total AC scores and ¹⁸F-FDG uptake in the ascending aorta was assessed using multivariate linear regression analysis. Results: In total, 68.26% were male, and a mean age was 67.10±14.70 years. Mean TBR values increased progressively with total AC score 0, 1-399, and ≥400 (1.01±0.07, 1.08±0.09, and 1.11±0.11, respectively; p<0.00001). Multivariate linear regression analysis revealed that increased total AC scores of 1-399 (β=0.06, 95% CI: 0.01-0.11, p=0.02) and ≥400 (β=0.11, 95% CI: 0.06-0.16, p<0.001) were significantly associated with higher Mean TBR. Conclusions: The current study demonstrated that total AC scores were associated with Mean TBR. Patients with a greater extent and severity of aortic calcifications may possess increased atherosclerotic inflammatory activity as measured by ¹⁸F-FDG PET/CT.

Consistent Abnormalities in Metabolic Patterns of Lewy Body Dementias

BACKGROUND

Whether dementia with Lewy bodies (DLB) and Parkinson's disease (PD) dementia (PDD) represent the same disease, distinct entities, or conditions within the same spectrum remains controversial.

OBJECTIVE

The objective of this study was to provide new insight into this debate by separately identifying disease-specific metabolic patterns and comparing them with each other and with previously established PD-related pattern (PDRP).

METHODS

Patients with DLB (n = 67), patients with PDD (n = 50), and healthy control subjects (HCs; n = 15) with brain ¹⁸ F-fluorodeoxyglucose positron emission tomography were enrolled as cohorts A and B for pattern identification and validation, respectively. Patients with PD (n = 30) were included for discrimination. Twenty-one participants had two scans. The principal component analysis was applied for pattern identification (DLB-related pattern [DLBRP], PDD-related pattern [PDDRP]). Similarities and differences among three patterns were assessed by pattern topography, pattern expression, clinical correlations cross-sectionally, and pattern expression changes longitudinally.

RESULTS

DLBRP and PDDRP shared highly similar topographies, with relative hypometabolism mainly in the middle temporal gyrus, middle occipital gyrus, lingual gyrus, precuneus, cuneus, angular gyrus, superior and inferior parietal gyrus, middle and inferior frontal gyrus, cingulate, and caudate, and relative hypermetabolism in the cerebellum, putamen, thalamus, precentral/postcentral gyrus, and paracentral lobule, which were more extensive than the PDRP. Patients with DLB and PDD could not be distinguished successfully by any pattern, but patients with PD were easily recognized, especially by DLBRP and PDDRP. The pattern expression of DLBRP and PDDRP showed similar efficacy in cross-sectional disease severity assessment and longitudinal progression monitoring.

CONCLUSIONS

The consistent abnormalities in metabolic patterns of DLB and PDD might underline the potential continuum across the clinical spectrum from PD to DLB. © 2022 International Parkinson and Movement Disorder Society.

Pulmonary actinomycosis mimicking lung cancer on 18F-fluorodeoxyglucose positron emission tomography: a case report

Background

Pulmonary actinomycosis is a chronic disease characterized by abscess formation, draining sinuses, fistulae, and tissue fibrosis. It can mimic other conditions, particularly malignant and granulomatous diseases, and is perhaps extremely challenging to diagnose.

Case presentation

A 64-year-old Japanese man presented with 6-week history of a painful solid lump in the chest wall. Chest computed tomography scan revealed a mass-like consolidation in the left upper lobe, with rib erosion and direct extension into the anterior chest wall. ¹⁸F-fluorodeoxyglucose positron emission tomography scan showed increased metabolic activity in the mass, which is indicative of primary lung cancer. The bronchoscopy and computed tomography scan-guided transthoracic biopsy results were considered nondiagnostic. Finally, the patient was diagnosed with pulmonary actinomycosis via surgical resection. He completed an 8-week course of antibiotic therapy and experienced no recurrence.

Conclusions

There is no difference in positron emission tomography/computed tomography scan findings between actinomycosis and malignancy. Therefore, pulmonary actinomycosis should be considered in the differential diagnosis of cases involving intensive activity on ¹⁸F-fluorodeoxyglucose positron emission tomography scan.

Quantifying the contribution of 18F-FDG PET to the diagnostic assessment of pediatric patients with fever of unknown origin: a systematic review and meta-analysis

BACKGROUND

The value of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) in the diagnostic assessment of pediatric fever of unknown origin is not known, and evidence from adults is not applicable.

OBJECTIVE

To quantify the contribution of ¹⁸F-FDG PET to pediatric fever of unknown origin, considering its diagnostic limitations.

MATERIALS AND METHODS

We searched PubMed, EMBASE and Cochrane Central Register of Controlled Trials up to Feb. 18, 2021. We included studies on patients with pediatric fever of unknown origin presenting sufficient data to calculate the likelihood of achieving definite diagnosis (based on pathology or clinical follow-up) between those with abnormal PET findings versus those with normal PET findings. We assessed the risk of bias using a modified Newcastle-Ottawa quality assessment scale and quantified the value of PET by pooling the likelihood of achieving definite diagnosis using a random-effects model.

RESULTS

We included 6 studies and found that pediatric patients with abnormal PET findings were about 17 times more likely to achieve definite diagnoses than those with normal PET findings (odds ratio [OR]: 16.75, 95% confidence interval [CI] 8.0-35, P < 0.00001). Sensitivity analyses using a fixed-effect model (OR 16.91, 95% CI 8.1-35, P < 0.0001) or removing one study at a time (OR 12-20, 95% CI lower bound 3.8-8.6, 95% CI upper bound 33-45, P < 0.0001) did not significantly alter the results. Sample size (interaction P = 0.75), imaging modality (interaction P = 0.29), length of follow-up (interaction P = 0.37), fever of unknown origin subclasses (interaction P = 0.89) and geographical areas (interaction P = 0.74) of studies showed no statistically significant influence on the results.

CONCLUSION

¹⁸F-FDG PET is a promising approach in the diagnostic work-up of pediatric fever of unknown origin. Further studies are warranted to support routine use in clinical care.

Comparative Analysis of Myocardial Viability Multimodality Imaging in Patients with Previous Myocardial Infarction and Symptomatic Heart Failure

Background and Objectives: To compare the accuracy of multimodality imaging (myocardial perfusion imaging with single-photon emission computed tomography (SPECT MPI), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET), and cardiovascular magnetic resonance (CMR) in the evaluation of left ventricle (LV) myocardial viability for the patients with the myocardial infarction (MI) and symptomatic heart failure (HF). Materials and Methods: 31 consecutive patients were included in the study prospectively, with a history of previous myocardial infarction, symptomatic HF (NYHA) functional class II or above, reduced ejection fraction (EF) ≤ 40%. All patients had confirmed atherosclerotic coronary artery disease (CAD), but conflicting opinions regarding the need for percutaneous intervention due to the suspected myocardial scar tissue. All patients underwent transthoracic echocardiography (TTE), SPECT MPI, 18F-FDG PET, and CMR with late gadolinium enhancement (LGE) examinations. Quantification of myocardial viability was assessed in a 17-segment model. All segments that were described as non-viable (score 4) by CMR LGE and PET were compared. The difference of score between CMR and PET we named reversibility score. According to this reversibility score, patients were divided into two groups: Group 1, reversibility score > 10 (viable myocardium with a chance of functional recovery after revascularization); Group 2, reversibility score ≤ 10 (less viable myocardium when revascularisation remains questionable). Results: 527 segments were compared in total. A significant difference in scores 1, 2, 3 group, and score 4 group was revealed between different modalities. CMR identified “non-viable” myocardium in 28.1% of segments across all groups, significantly different than SPECT in 11.8% PET in 6.5% Group 1 (viable myocardium group) patients had significantly higher physical tolerance (6 MWT (m) 3892 ± 94.5 vs. 301.4 ± 48.2), less dilated LV (LVEDD (mm) (TTE) 53.2 ± 7.9 vs. 63.4 ± 8.9; MM (g) (TTE) 239.5 ± 85.9 vs. 276.3 ± 62.7; LVEDD (mm) (CMR) 61.7 ± 8.1 vs. 69.0 ± 6.1; LVEDDi (mm/m2) (CMR) 29.8 ± 3.7 vs. 35.2 ± 3.1), significantly better parameters of the right heart (RV diameter (mm) (TTE) 33.4 ± 6.9 vs. 38.5 ± 5.0; TAPSE (mm) (TTE) 18.7 ± 2.0 vs. 15.2 ± 2.0), better LV SENC function (LV GLS (CMR) −14.3 ± 2.1 vs. 11.4 ± 2.9; LV GCS (CMR) −17.2 ± 4.6 vs. 12.7 ± 2.6), smaller size of involved myocardium (infarct size (%) (CMR) 24.5 ± 9.6 vs. 34.8 ± 11.1). Good correlations were found with several variables (LVEDD (CMR), LV EF (CMR), LV GCS (CMR)) with a coefficient of determination (R2) of 0.72. According to the cut-off values (LVEDV (CMR) > 330 mL, infarct size (CMR) > 26%, and LV GCS (CMR) < −15.8), we performed prediction of non-viable myocardium (reversibility score < 10) with the overall percentage of 80.6 (Nagelkerke R2 0.57). Conclusions: LGE CMR reveals a significantly higher number of scars, and the FDG PET appears to be more optimistic in the functional recovery prediction. Moreover, using exact imaging parameters (LVEDV (CMR) > 330 mL, infarct size (CMR) > 26% and LV GCS (CMR) < −15.8) may increase sensitivity and specificity of LGE CMR for evaluation of non-viable myocardium and lead to a better clinical solution (revascularization vs. medical treatment) even when viability is low in LGE CMR, and FDG PET is not performed.

Imaging modalities for monitoring acute therapeutic effects after near-infrared photoimmunotherapy in vivo

Near-infrared photoimmunotherapy (NIR-PIT) induces immediate cell death after irradiation with near-infrared (NIR) light. Acute therapeutic effects caused by NIR-PIT before the change of tumor size is essential to be monitored by imaging modalities. We summarized and compared the imaging modalities for evaluating acute therapeutic effects after NIR-PIT, and aimed to provide a better understanding of advantages and disadvantages of each modality for evaluation in clinical applications. Fluorescence imaging and fluorescence lifetime, with high resolution, remains high accumulation of fluorescence dyes in the normal organs. High resolution and noninvasiveness are the major advantages of magnetic resonance imaging, while ¹⁸ F-fluorodeoxyglucose positron emission tomography provides information about the glucose metabolism. Optical coherence tomography provided more information about the blood vessels. Thus, all of the imaging modalities play an important role in evaluating acute therapeutic effects after NIR-PIT. Clinicians should choose suitable modality according to specific purpose and conditions in clinical application.

Deep-Learning Radiomics for Discrimination Conversion of Alzheimer's Disease in Patients With Mild Cognitive Impairment: A Study Based on 18F-FDG PET Imaging

Objectives: Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and the most common form of dementia in the older people. Some types of mild cognitive impairment (MCI) are the clinical precursors of AD, while other MCI forms tend to remain stable over time and do not progress to AD. To discriminate MCI patients at risk of AD from stable MCI, we propose a novel deep-learning radiomics (DLR) model based on 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) images and combine DLR features with clinical parameters (DLR+C) to improve diagnostic performance. Methods: 18F-fluorodeoxyglucose positron emission tomography (PET) data from the Alzheimer's disease Neuroimaging Initiative database (ADNI) were collected, including 168 patients with MCI who converted to AD within 3 years and 187 patients with MCI without conversion within 3 years. These subjects were randomly partitioned into 90 % for the training/validation group and 10 % for the independent test group. The proposed DLR approach consists of three steps: base DL model pre-training, network features extraction, and integration of DLR+C, where a convolution network serves as a feature encoder, and a support vector machine (SVM) operated as the classifier. In comparative experiments, we compared our DLR+C method with four other methods: the standard uptake value ratio (SUVR) method, Radiomics-ROI method, Clinical method, and SUVR + Clinical method. To guarantee the robustness, 10-fold cross-validation was processed 100 times. Results: Under the DLR model, our proposed DLR+C was advantageous and yielded the best classification performance in the diagnosis of conversion with the accuracy, sensitivity, and specificity of 90.62 ± 1.16, 87.50 ± 0.00, and 93.39 ± 2.19%, respectively. In contrast, the respective accuracy of the other four methods reached 68.38 ± 1.27, 73.31 ± 6.93, 81.09 ± 1.97, and 85.35 ± 0.72 %. These results suggested the DLR approach could be used successfully in the prediction of conversion to AD, and that our proposed DLR-combined clinical information was effective. Conclusions: This study showed DLR+C could provide a novel and valuable method for the computer-assisted diagnosis of conversion to AD from MCI. This DLR+C method provided a quantitative biomarker which could predict conversion to AD in MCI patients.

Investigating the Roles of Anterior Cingulate in Behavioral Variant Frontotemporal Dementia: A PET/MRI Study

Background:

The anterior cingulate cortex (ACC) seems to play an important role in behavioral deficits and executive dysfunctions in patients with behavioral variant frontotemporal dementia (bvFTD), while its specific and independent contribution requires clarification.

Objective:

To identify whether ACC abnormalities in gray matter (GM) volume and standardized uptake value ratio (SUVR) images are associated with disease severity of bvFTD, by analyzing hybrid T1 and ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET).

Methods:

We enrolled 21 bvFTD patients and 21 healthy controls in the study. Each subject underwent a hybrid PET/MRI study and a standardized neuropsychologic assessment battery. GM volume and SUVR are voxel-wise calculated and compared. Then we estimate the mean value inside ACC for further partial Pearson’s correlation to explore the association between GM volume/SUVR of the ACC and severity of behavioral deficit as well as executive dysfunction.

Results:

ACC was shown to be involved in both atrophy and hypometabolism patterns. The partial Pearson’s correlation analysis showed that the SUVR of the ACC was strongly correlated with frontal behavior inventory total score (left r = –0.85, right r = –0.85, p < 0.0001), disinhibition subscale score (left r = –0.72, p = 0.002; right = –0.75, p < 0.0001), and apathy subscale score (left = –0.87, right = –0.85, p < 0.0001).

Conclusion:

These findings demonstrated decreased ACC activity contributes to behavioral disturbances of both apathetic and disinhibition syndromes of bvFTD, which can be sensitively detected using ¹⁸F-FDG PET.

Relationship between Cerebrospinal Fluid Matrix Metalloproteinases Levels and Brain Amyloid Deposition in Mild Cognitive Impairment

This study aimed to explore whether cerebrospinal fluid (CSF) levels of matrix metalloproteinases (MMPs), and their inhibitors (TIMPs) were associated with brain amyloid deposition, cortical glucose metabolism, and white matter lesions (WMLs) in individuals with amnestic mild cognitive impairment (MCI). A total of 33 individuals with amnestic MCI (mean age, 75.6 years) underwent ¹¹C-Pittsburgh compound B positron emission tomography (PiB-PET), ¹⁸F-fluorodeoxyglucose positron emission tomography, magnetic resonance imaging or computed tomography, and CSF analysis. PET uptake of the frontal and temporoparietal lobes and posterior cingulate gyrus was assessed using the cerebellar cortex as the reference region. WMLs were assessed by the Fazekas scale. CSF levels of MMPs and TIMPs were measured with bead-based multiplex assays. After adjusting for covariates, multiple linear regression analysis showed that CSF levels of MMP-2 were negatively correlated with global PiB uptake (p = 0.035), especially in the parietotemporal lobe and posterior cingulate gyrus (p = 0.016 and p = 0.041, respectively). Moreover, CSF levels of MMP-7 were positively correlated with the severity of WMLs (p = 0.033). CSF levels of MMP-2 and MMP-7 are associated with brain amyloid deposition and severity of WMLs, respectively. These findings provide valuable insights into the role of MMPs in amyloid β catabolism and blood-brain barrier integration at the MCI stage.

The Behavioral/Dysexecutive Variant of Alzheimer's Disease: A Case Series with Clinical, Neuropsychological, and FDG-PET Characterization

INTRODUCTION

It is well known that some patients with Alz-heimer's disease (AD) have atypical, nonamnestic presentations. While logopenic aphasia and posterior cortical atrophy are well-characterized atypical variants of AD, the behavioral/dysexecutive variant remains a controversial entity, lacking consensus regarding its distinctive clinical and imaging features.

METHODS

We present a case series of 8 patients with biomarker confirmation of AD (cerebrospinal fluid [CSF] analysis or amyloid positron emission tomography [PET]) and a progressive frontal syndrome, defined as prominent behavioral and/or executive deficits at initial presentation. We characterize the cohort based on clinical features, cognitive performance in 4 domains (memory, visuospatial, executive, and language) as well as behavior on the Dépistage Cognitif de Québec (DCQ), and regional brain metabolism using 18F-fluorodeoxyglucose PET (FDG-PET). We compare these features with 8 age-matched patients diagnosed with the behavioral variant of frontotemporal dementia (bvFTD) and 37 patients with typical amnestic AD.

RESULTS

Patients with the behavioral/dysexecutive variant of AD presented with early-onset (mean age: 59 years old) progressive executive and behavioral problems reminiscent of bvFTD, including disinhibition, loss of social conventions, and hyperorality. Patients scored higher on the Memory Index and lower on the Behavioral Index than patients with amnestic AD on the DCQ, yet they were indistinguishable from patients with bvFTD on each of the cognitive indices. Visual analysis of FDG-PET revealed half of patients with behavioral/dysexecutive AD presented with frontal hypometabolism suggestive of bvFTD and only 3/8 (37.5%) presented significant hypometabolism of the posterior cingulate cortex. Group-level analysis of FDG-PET data revealed that the most hypometabolic regions were the middle temporal, inferior temporal, and angular gyri in behavioral/dysexecutive AD and the inferior frontal gyrus, anterior cingulate cortex, caudate nucleus, and insula in bvFTD.

CONCLUSION

The behavioral/dysexecutive variant of AD is a rare, atypical young-onset variant of AD defined clinically by early and prominent impairments in executive and behavioral domains. While behavioral/dysexecutive AD is hardly distinguishable from bvFTD using clinical and cognitive features alone, CSF biomarkers and temporoparietal hypometabolism help predict underlying pathology during life.

Syncope and Cardiac Tamponade: Multimodality Imaging of Primary Cardiac Lymphoma

Primary cardiac lymphoma (PCL) is among the rarest heart neoplasms. Its estimated incidence is about 1%-2% among primary cardiac tumor and 0.5% of extranodal lymphoma. It usually causes heart failure, pericardial effusion, tamponade, and arrhythmias. Prognosis is poor; treatment is combined medical and surgical. We described the case of a 62-year-old male with PLC that presented with syncope and cardiac tamponade, submitted to R-CHOP therapy because of failure of surgery. Clinical state is stable 3 months after diagnosis and first chemotherapy cycle.

Deep learning-based image quality improvement of 18F-fluorodeoxyglucose positron emission tomography: a retrospective observational study

Background

Deep learning (DL)-based image quality improvement is a novel technique based on convolutional neural networks. The aim of this study was to compare the clinical value of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) images obtained with the DL method with those obtained using a Gaussian filter.

Methods

Fifty patients with a mean age of 64.4 (range, 19–88) years who underwent ¹⁸F-FDG PET/CT between April 2019 and May 2019 were included in the study. PET images were obtained with the DL method in addition to conventional images reconstructed with three-dimensional time of flight-ordered subset expectation maximization and filtered with a Gaussian filter as a baseline for comparison. The reconstructed images were reviewed by two nuclear medicine physicians and scored from 1 (poor) to 5 (excellent) for tumor delineation, overall image quality, and image noise. For the semi-quantitative analysis, standardized uptake values in tumors and healthy tissues were compared between images obtained using the DL method and those obtained with a Gaussian filter.

Results

Images acquired using the DL method scored significantly higher for tumor delineation, overall image quality, and image noise compared to baseline (P < 0.001). The Fleiss’ kappa value for overall inter-reader agreement was 0.78. The standardized uptake values in tumor obtained by DL were significantly higher than those acquired using a Gaussian filter (P < 0.001).

Conclusions

Deep learning method improves the quality of PET images.

18F-fluorodeoxyglucose positron emission tomography for the detection of inflammatory lesions of the arterial vessel walls in Wistar rats

The present study aimed to evaluate the use of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) for detection of high-fat and high-salt diet-induced inflammatory lesions of the arterial vessel walls in Wistar rats. A total of 20 healthy, 8-week-old, male Wistar rats were randomly assigned to the high-fat diet group and the normal diet group. After 16 and 24 weeks of feeding, Wistar rats in the normal diet group and the high-fat diet group (five rats in each group) were injected with ¹⁸F-FDG through the tail vein at a dose of 1 mCi/kg after fasting for 12 h. After 1 h, the rats were anesthetized with 2% isoflurane, followed by micro-PET imaging with a 10-min image capture duration and immunohistochemical staining. The standardized uptake values (SUVs) of ¹⁸F-FDG were significantly higher in the iliac artery in the high-fat diet group compared with those in the normal diet group at 16 weeks (1.53±0.08 vs. 1.04±0.03; P<0.05) and at 24 weeks (1.96±0.17 vs. 1.12±0.07; P<0.05). The SUVs of ¹⁸F-FDG were also significantly greater in the abdominal aorta in the high-fat diet group compared with those in the normal diet group at 16 weeks (1.35±0.08 vs. 1.02±0.02; P<0.05) and at 24 weeks (1.54±0.09 vs. 1.04±0.02; P<0.05). In addition, the SUVs of ¹⁸F-FDG in the iliac artery and abdominal aorta were significantly higher at 24 weeks compared with those at 16 weeks in the high-fat diet group (P<0.05). As determined by immunohistochemistry, the percentage of CD68-positive cells in the total number of cells per unit area in each group was 3.20±1.80% in the 24-week normal diet group, 4.70±2.02% in the 16-week high-fat diet group and 6.94±2.02% in the 24-week high-fat diet group; the percentage of CD68-positive cells in the high-fat diet group at 24 weeks was significantly higher than that in the high-fat diet group at 16 weeks and in the normal diet group at 24 weeks (P<0.05). In conclusion, ¹⁸F-FDG PET is a noninvasive imaging tool that can continuously monitor inflammatory lesions of the arterial vessel walls in Wistar rats. Further improvement of the Wistar rat atherosclerosis model may provide data to support the early assessment of and intervention in atherosclerosis.

18F-FDG uptake of the right ventricle is an important predictor of histopathologic diagnosis by endomyocardial biopsy in patients with cardiac sarcoidosis

BACKGROUND

The aim of this study was to determine whether right ventricle (RV) 18F-fluorodeoxyglucose (FDG) uptake can predict positive findings of endomyocardial biopsy (EMB) in patients with cardiac sarcoidosis (CS).

METHODS

70 consecutive patients with clinically diagnosed CS who had undergone FDG PET were registered in the present study. Patients without EMB (n = 42) were excluded. Ultimately, 28 patients were studied. EMB samples were obtained from the RV septum. We evaluated the FDG uptake on six segments (RV, left ventricle anterior, septal, lateral, inferior, and apex).

RESULTS

Positive EMB was found in six patients (21%). Patients were divided into two groups according to positive (n = 12 [43%]) or negative (n = 16 [57%]) RV FDG uptake. Patients with positive RV FDG uptake had a significantly higher frequency of positive EMB than those without (42% vs. 6%, P = 0.024). On the other hand, there was no EMB-predictive value for the FDG uptakes in the other five segments, the cardiac metabolic volume, total lesion glycolysis, left ventricular ejection fraction, or any electrocardiogram findings.

CONCLUSIONS

FDG uptake of the RV but no other heart segment was associated with positive EMB in CS patients. The presence of RV FDG uptake could improve the rate of positive EMB up to 42% in patients with CS.

Prognostic value of 18F-fluorodeoxyglucose positron emission tomography in patients with small hepatocellular carcinoma treated by radiofrequency ablation

BACKGROUND

¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake in hepatocellular carcinoma (HCC) is significantly associated with early recurrence and survival after curative surgical resection. However, there are no reports regarding the relationship between ¹⁸F-FDG uptake and outcomes after radiofrequency ablation (RFA). A prospective cohort study was conducted to evaluate the prognostic value of ¹⁸F-FDG positron emission tomography (PET) in HCC patients after RFA.

METHODS

A total of 121 consecutive patients with primary HCC (≤3 tumors, of diameter ≤ 3 cm) without vascular invasion on imaging were examined by ¹⁸F-FDG-PET computed tomography prior to RFA. An HCC with a component of ¹⁸F-FDG uptake visibly stronger than that of surrounding liver was defined as ¹⁸F-FDG-PET positive.

RESULTS

The median follow-up period was 1267 days. There were 110 ¹⁸F-FDG-PET negative and 11 positive tumors. The cumulative 1-year recurrence rates in the ¹⁸F-FDG negative and positive groups were 30 and 64% (P = 0.017), respectively, and cumulative 1-year metastatic recurrence rates were 6 and 36% (P < 0.001), respectively. The cumulative 5-year survival rates were 88 and 22% (P < 0.001), respectively. Multivariate analysis revealed ¹⁸F-FDG-PET positivity and tumor size as independent factors related to metastatic recurrence and survival after RFA.

CONCLUSIONS

¹⁸F-FDG-PET positivity was significantly associated with outcomes after RFA. RFA should not be readily selected as the first-line treatment for small HCC that includes a component of visually strong ¹⁸F-FDG uptake.

DaPeCa-7: comparative assessment of fluorodeoxyglucose positron emission tomography/computed tomography (CT) and conventional diagnostic CT in diagnosis of lymph node metastases, distant metastases and incidental findings in patients with invasive penile cancer

OBJECTIVES

To evaluate diagnostic accuracy of ¹⁸ F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) compared to contrast-enhanced CT in assessment of inguinal lymph node (ILN) metastases, distant metastases and synchronous cancers in patients with penile squamous cell carcinoma (pSCC).

PATIENTS AND METHODS

During a 4-year period, patients with pSCC were scheduled for FDG PET/CT prior to surgical treatment at two referral centres that manage all penile cancers in Denmark. The primary endpoint was diagnostic accuracy of FDG PET/CT and of CT alone with histopathology or Response Evaluation Criteria In Solid Tumors (RECIST) as reference.

RESULTS

We evaluated 171 patients for distant metastases and synchronous incident cancers and examined 286 groins in 143 patients for LN metastases by FDG PET/CT. Six groins disclosed false negatives. FDG PET/CT sensitivity was 85.4% per patient. In 135 patients (270 groins), CT images were evaluated separately and 22 groins disclosed false negatives. CT sensitivity was 47.5% per patient. FDG PET/CT detected pSCC distant metastases in seven patients. Distant metastases from other cancers were newly detected in three patients. In eight patients, an incidental synchronous cancer was detected. Seven out of the 18 distant malignancies detected depended on FDG PET information.

CONCLUSION

This study underlines the increased diagnostic accuracy of FDG PET/CT compared to CT alone in the evaluation of ILN status. In patients with palpable LNs, the advantage of FDG PET/CT over CT is less pronounced. FDG PET/CT may play a role in penile cancer evaluation.

18F-FDG-PET/CT in the evaluation and differential diagnosis of active large-vessel vasculitis. A prospective study

Introduction: Large-vessel vasculitis has non-specific clinical symptoms, which can delay the diagnosis. Early recognition and treatment of the disease can help to avoid late complications. ¹⁸ F-FDG-PET can detect the inflammation of the vessel wall in the early stage of the disease with high sensitivity. CT is used to localize vasculitis. Aim: To examine the performance of ¹⁸F-FDG-PET/CT in patients with suspected large-vessel vasculitis, during relapse and remission, focusing on disease activity and extent. Method: 43 patients were evaluated. They were classified according to the clinical questions: steroid-naive suspected vasculitis, suspected vasculitis on steroid treatment, patients with relapse and in remission. We examined 10 cancer patients in control. We carried out visual and quantitative analysis of the ¹⁸F-FDG uptake of vessel walls. During quantitative evaluation, we determined standardised uptake values (SUVmax) of vessel wall segments compared to liver. Results: We found active disease in 5 patients examined for primary diagnosis, moreover, in 5 patients with relapse. The disease involved 3 or more vessel segments in fifty percent of the active cases. In the visually active group, the SUVmax was significantly lower in patients on steroid treatment than in steroid-naive cases (1.17 ± 0.11 vs. 1.43 ± 0.29; p = 0.005). We confirmed remission in 2 cases after therapy. In the inactive group, we found other types of inflammatory disorders in 8 cases. Conclusion: ¹⁸F-FDG-PET/CT is an effective diagnostic tool for large-vessel vasculitis, and can be used to determine the activity and extent of the disease. Steroid treatment influences the ¹⁸F-FDG-uptake of vessel wall. Orv Hetil. 2020; 161(20): 829-838.

Value of Pretreatment 18F-fluorodeoxyglucose Positron Emission Tomography in Patients With Localized Pancreatic Cancer Treated With Neoadjuvant Therapy

Background:¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) imaging is not routine in patients with localized pancreatic cancer (PC). We evaluated the prognostic value of PET/CT in patients who received neoadjuvant therapy.

Methods: Patients with localized PC underwent pretreatment PET/CT with or without posttreatment (preop) PET/CT. Maximum standardized uptake values (SUV) were classified as high or low based on a cut point of 7.5 at diagnosis (SUV_dx) and 3.5 after neoadjuvant therapy (preoperative; SUV_preop). Preop carbohydrate antigen 19-9 (CA19-9) was classified as normal ( ≤ 35 U/mL) or elevated.

Results: Pretreatment PET/CT imaging was performed on 201 consecutive patients; SUV_dx was high in 98 (49%) and low in 103 (51%). Preop PET/CT was available in 104 (52%) of the 201 patients; SUV_preop was high in 60 (58%) and low in 44 (42%). Following neoadjuvant therapy, preop CA19-9 was normal in 90 (45%) patients and elevated in 111 (55%). Median overall survival (OS) of all patients was 27 months; 33 months for the 103 patients with a low SUV_dx and 22 months for the 98 patients with a high SUV_dx (p = 0.03). Median OS for patients with low SUV_dx/normal preop CA19-9, high SUV_dx/normal preop CA19-9, low SUV_dx/elevated preop CA19-9, and high SUV_dx/elevated preop CA19-9 were 66, 34, 23, and 17 months, respectively (p < 0.0001). OS was 44 months for the 148 (74%) patients who completed all intended neoadjuvant therapy and surgery and 13 months for the 53 (26%) who did not undergo surgery (p < 0.001).

Conclusion: Pretreatment PET/CT avidity and preop CA19-9 are clinically significant prognostic markers in patients with PC.

A Case Report of a Solitary Pelvic Mass Proven to Be a Lymph Nodal Metastasis from Anal Cancer

A solitary pelvic-wall lymph nodal metastasis can be mistaken as a primary malignancy when a primary tumor has not been diagnosed. We report the case of a 72-year-old woman with a solitary left pelvic-wall mass that was finally proven to be a left internal iliac lymph nodal metastasis from anal cancer. No signs of the primary tumor had been initially found by general screening using computed tomography, colonoscopy, pelvic magnetic resonance imaging, and gynecological/urological examination; however, squamous cell carcinoma was detected by surgical biopsy of the left pelvic-wall mass. Additional ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) showed focal accumulations in the left pelvic mass and the anal canal. A biopsy of the induration in the anal canal led to the diagnosis of anal cancer, clinical T2N2M0, and stage IIIB (UICC-TNM 7th ed.), which was indicated for definitive chemoradiotherapy. Two months after completing a definitive chemoradiotherapy for anal cancer, a fixed induration developed under the surgical wound along with the surgical tract of the biopsy site. Physical examination and ¹⁸F-FDG-PET/computed tomography led to the clinical diagnosis of unresectable surgical tract recurrence of anal cancer. The patient underwent palliative treatment and died 14 months after the diagnosis of the surgical tract recurrence. In conclusion, anal cancer may present as a solitary pelvic mass without any anal symptoms. To evaluate the solitary pelvic mass, ¹⁸F-FDG-PET/computed tomography, along with digital examination, will probably help in establishing an accurate diagnosis. Anal cancer must be considered during the differential diagnosis of a solitary pelvic-wall mass for a correct diagnosis and to avoid unnecessary procedures.

Therapeutic Antibody Against Phosphorylcholine Preserves Coronary Function and Attenuates Vascular 18F-FDG Uptake in Atherosclerotic Mice

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Phosphorylcholine is a pro-inflammatory epitope in atherogenic oxidized phospholipids.

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This study investigated effects of a novel monoclonal IgG1 antibody against PC on vascular function and atherosclerotic inflammation.

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Treatment with phosphorylcholine antibody preserved coronary flow reserve and decreased uptake of ¹⁸F-FDG in atherosclerotic lesions in hypercholesterolemic mice.

•

Noninvasive imaging techniques represent translational tools to assess the efficacy of phosphorylcholine-targeted therapy on coronary artery function and atherosclerosis.

This study showed that treatment with a therapeutic monoclonal immunoglobulin-G1 antibody against phosphorylcholine on oxidized phospholipids preserves coronary flow reserve and attenuates atherosclerotic inflammation as determined by the uptake of ¹⁸F-fluorodeoxyglucose in atherosclerotic mice. The noninvasive imaging techniques represent translational tools to assess the efficacy of phosphorylcholine-targeted therapy on coronary artery function and atherosclerosis in clinical studies.

Diagnostic Capabilities of MRI Versus 18F FDG PET-CT in Postoperative Patients with Thyroglobulin Positive, 131I-negative Local Recurrent or Metastatic Thyroid Cancer

BACKGROUND

The detection of recurrence or metastasis might be challenging in patients, who underwent total thyroidectomy and radioactive iodine therapy for Differentiated Thyroid Carcinoma (DTC), with increased serum Thyroglobulin (Tg) levels and negative 131I whole body scan (131I-WBS) results.

AIMS

The purpose of this study was to compare the ability of Magnetic Resonance Imaging (MRI) and 18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography (18F FDG PET-CT) to detect recurrence or cervical and upper mediastinal metastases in postoperative DTC patients who had negative 131I-WBS despite elevated serum Tg levels.

STUDY DESIGN

This study has a retrospective study design.

METHODS

We evaluated cervical and upper mediastinal MRI and 18F FDG PET-CT of 32 postoperative patients with DTC (26 patients with papillary thyroid carcinoma and 6 patients with follicular thyroid carcinoma).

RESULTS

We evaluated 44 lesions in 32 patients. For all lesions, the Positive Predictive Value, (PPV) Negative Predictive Value (NPV), sensitivity, specificity, and accuracy of MRI were 81.4%, 76.4%, 84.6%, 72.2%, and 79.5% respectively. The PPV, NPV, sensitivity, specificity, and accuracy of 18F FDG PET-CT were 100.0%, 85.7%, 88.4%, 100.0%, and 93.1%, respectively.

CONCLUSION

Although we could not replace 18F FDG PET-CT, MRI might be used as an adjunct to 18F FDG PET-CT for the evaluation of recurrent or cervical and upper mediastinal metastatic thyroid cancers; however, MRI is inadequate for the detection of metastases in small lymph nodes.

Detection of Active Inflammation Status Around Ventricular Aneurysms in Patients With Cardiac Sarcoidosis

BACKGROUND

Little is known about the pattern of isotope accumulation in the heart on ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography in patients with cardiac sarcoidosis (CS) complicated by ventricular aneurysm (VA).Methods and Results:We prospectively enrolled 82 consecutive patients with CS; 54 patients with active CS (presence of abnormal ¹⁸F-FDG accumulation in the heart) were subdivided into VA (n=17) and non-VA groups (n=37). Strong ¹⁸F-FDG accumulation surrounding the VA and its disappearance in the VA center was observed in all patients with VA, probably because of scar formation at the VA. Peak standardized uptake value was higher around the VA than in the VA center (5.1±2.1 vs. 2.2±0.6, P=0.0003) and the VA center had no ¹⁸F-FDG accumulation (VA center: 2.2±0.6 vs. control area: 2.1±0.6, P=0.37). On the other hand, in non-VA patients with LV wall thinning (n=28), ¹⁸F-FDG accumulation was significantly high, even in the area of LV wall thinning (LV wall thinning area: 3.1±0.8 vs. control area: 2.0±0.6, P=0.00002).

CONCLUSIONS

A pattern of strong ¹⁸F-FDG accumulation surrounding the VA and its disappearance in the VA center might be characteristic in patients with CS complicated by VA. Careful attention to FDG uptake would further elucidate CS pathophysiology and aid in the early treatment of VA.

Diagnosis of mild cognitive impairment using multiple neuroimaging modalities in addition to the Mini-Mental State Examination

AIM

This prospective study investigated the additional utility of combining multiple imaging modalities with the Mini-Mental State Examination (MMSE) in discriminating individuals with mild cognitive impairment (MCI) from cognitively normal individuals.

METHODS

A total of 103 individuals with amnestic MCI and normal cognitive function were recruited from outpatients; they underwent examination using the MMSE, magnetic resonance imaging, ¹⁸ F-fluorodeoxyglucose positron emission tomography and ¹¹ C-Pittsburgh compound B positron emission tomography. Binary logistic regression with receiver operator characteristic analysis was used to assess the combination of the abovementioned single or multiple imaging modalities with the MMSE. Eight models were constructed, and their area under the curve values and misclassification rates in discriminating individuals with amnestic MCI from cognitively normal individuals were evaluated.

RESULTS

The addition of each of the imaging modalities improved the discrimination accuracy over that of the MMSE alone; the accuracy obtained with the addition of ¹⁸ F-fluorodeoxyglucose positron emission tomography was the highest. The best model with the highest accuracy included a combination of all the imaging modalities in addition to the MMSE (area under the curve value 0.902).

CONCLUSIONS

The combination of all the imaging modalities in addition to the MMSE could facilitate more accurate diagnosis of amnestic MCI. Of the individual imaging modalities, the highest accuracy resulted from the addition of ¹⁸ F-fluorodeoxyglucose positron emission tomography to the MMSE. Geriatr Gerontol Int 2019; 19: 1193-1197.

Magnetic resonance angiography versus 18F-fluorodeoxyglucose positron emission tomography in large vessel vasculitis

With advances in our understanding of the pathogenesis of large vessel vasculitides, we recognise the persistence of inflammation in large vessels, sometimes despite therapy to control clinical symptoms. Achieving an early diagnosis and establishing the extent of disease are important steps in improving our management of these diseases. Imaging is playing an increasing role in the assessment of these patients from diagnosis to prognosis. We review the current and potential role of two important and potentially complementary imaging techniques of magnetic resonance angiography and 18F-fluorodeoxyglucose positron emission tomography in the evaluation of patients with giant cell arteritis and Takayasu arteritis.

Mycobacterial Lymphadenitis in a Human Immunodeficiency Virus-Infected Patient: Usefulness of 18F-Fluorodeoxyglucose Positron Emission Tomography for Diagnosis and Monitoring the Response to Treatment

Lymphadenitis, due to typical or atypical Mycobacterium, is a clinical condition frequently associated with human immunodeficiency virus (HIV) infection. Differential diagnosis between benign and malignant causes may be a challenge for clinicians. In this regard, the role of positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) has still not been fully explored. We describe a case of 30-year-old male, infected by HIV, with mycobacterial lymphadenitis, in which ¹⁸FDG-PET and PET-derived parameters resulted useful for guiding diagnosis and monitoring the response to treatment.

Imaging plaque inflammation in asymptomatic cocaine addicted individuals with simultaneous positron emission tomography/magnetic resonance imaging

BACKGROUND

Chronic cocaine use is associated with stroke, coronary artery disease and myocardial infarction, resulting in severe impairments or sudden mortality. In the absence of clear cardiovascular symptoms, individuals with cocaine use disorder (iCUD) seeking addiction treatment receive mostly psychotherapy and psychiatric pharmacotherapy, with no attention to vascular disease (i.e., atherosclerosis). Little is known about the pre-clinical signs of cardiovascular risk in iCUD and early signs of vascular disease are undetected in this underserved population.

AIM

To assess inflammation, plaque burden and plaque composition in iCUD aiming to detect markers of atherosclerosis and vascular disease.

METHODS

The bilateral carotid arteries were imaged with positron emission tomography/magnetic resonance imaging (PET/MRI) in iCUD asymptomatic for cardiovascular disease, healthy controls, and individuals with cardiovascular risk. PET with 18F-fluorodeoxyglucose (¹⁸F-FDG) evaluated vascular inflammation and 3-D dark-blood MRI assessed plaque burden including wall area and thickness. Drug use and severity of addiction were assessed with standardized instruments.

RESULTS

The majority of iCUD and controls had carotid FDG-PET signal greater than 1.6 but lower than 3, indicating the presence of mild to moderate inflammation. However, the MRI measure of wall structure was thicker in iCUD as compared to the controls and cardiovascular risk group, indicating greater carotid plaque burden. iCUD had larger wall area as compared to the healthy controls but not as compared to the cardiovascular risk group, indicating structural wall similarities between the non-control study groups. In iCUD, wall area correlated with greater cocaine withdrawal and craving.

CONCLUSION

These preliminary results show markers of carotid artery disease burden in cardiovascular disease-asymptomatic iCUD. Broader trials are warranted to develop protocols for early detection of cardiovascular risk and preventive intervention in iCUD.

Combinative evaluation of primary tumor and lymph nodes in predicting pelvic lymphatic metastasis in early-stage cervical cancer: A multiparametric PET-CT study

PURPOSE

The purpose of this study is to investigate the value of combining tumor and pelvic lymph node (PLN) characteristics on PET-CT in predicting PLN metastasis of patients with early-stage cervical cancer, specifically to further reduce the false-negative cases of diagnosis.

METHODS

The [18F] FDG PET-CT imaging data of 394 patients who were newly diagnosed with cervical cancer (FIGO stage, Ia-IIa) were retrospectively studied. We measured size, total lesion glycolysis (TLG) of tumor, metabolic tumor volume (MTV), maximum and mean standardized uptake value (SUVmax, SUVmean) of tumor and lymph node (LN). Diagnostic efficiency was evaluated using receiver operator characteristic (ROC) curve. We also investigated additional CT diagnosis information in PET-negative cases.

RESULTS

Our results indicated both lymph node and tumor parameters were independent risk factors for lymphatic metastasis in early-stage cervical cancer. The diagnosis based on above meaningful parameters, we name it 'combination diagnosis', offered significantly higher predictive value than that based on SUV measurement alone, which the values of AUC were 0.842 and 0.784 respectively (P < 0.05). In PET-negative cases, we also found that tumor TLG, suspicious LN in lymphatic drainage pathway, long/short axis of LN ≤ 2, heterogeneity of LN significantly associated with PLN metastasis. ROC analysis showed combination diagnosis of all these parameters above produced an AUC value of 0.859 (P < 0.05, 95% CI, 0.811-0.899), which was significantly higher than either using tumor TLG alone (AUC = 0.622, Z = 3.919, P < 0.05) or indices derived from CT alone (AUC = 0.727, 0.668, 0.695. Z = 3.620, 5.356, 3.696, P < 0.05).

CONCLUSIONS

We proposed a combination diagnosis method that can better predict PLN metastasis for patients with early-stage cervical cancer. In PET-negative cases, combination diagnosis of TLG of tumor and CT indicators also produced improved prediction by reducing false-negative cases of diagnosis. This combination diagnosis approach has significant implications in cervical cancer patient management and treatment planning.

The Value of 18F-FDG PET in the Diagnosis of Intertrabecular Vertebral Metastasis in a Small Cell Lung Cancer Patient with a High Serum CEA Level

We encountered a small cell lung cancer (SCLC) patient with intertrabecular vertebral metastasis (IVM). A 59-year-old man was admitted to our hospital with weight loss. ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET)-CT demonstrated the uptake of fluorodeoxyglucose in the hilum of the left lung and whole-body bones. Despite intensive support, the patient died within a month. Subsequent autopsy revealed a small lesion consisting of small round cells in the left lung. The cancer cells were found to have spread through the replacement of the bone marrow cells while sparing the trabecular bone. This case demonstrated the potential of ¹⁸F-FDG PET for detecting IVM in SCLC patients.

Metabolic Subtyping of Pheochromocytoma and Paraganglioma by 18F-FDG Pharmacokinetics Using Dynamic PET/CT Scanning

Static single-time-frame ¹⁸F-FDG PET/CT is useful for the localization and functional characterization of pheochromocytomas and paragangliomas (PPGLs). ¹⁸F-FDG uptake varies between PPGLs with different genotypes, and the highest SUVs are observed in cases of succinate dehydrogenase (SDH) mutations, possibly related to enhanced aerobic glycolysis in tumor cells. The exact determinants of ¹⁸F-FDG accumulation in PPGLs are unknown. We performed dynamic PET/CT scanning to assess whether in vivo ¹⁸F-FDG pharmacokinetics has added value over static PET to distinguish different genotypes. Methods: Dynamic ¹⁸F-FDG PET/CT was performed on 13 sporadic PPGLs and 13 PPGLs from 11 patients with mutations in SDH complex subunits B and D, von Hippel-Lindau (VHL), RET, and neurofibromin 1 (NF1). Pharmacokinetic analysis was performed using a 2-tissue-compartment tracer kinetic model. The derived transfer rate-constants for transmembranous glucose flux (K ₁ [in], k ₂ [out]) and intracellular phosphorylation (k ₃), along with the vascular blood fraction (V_b), were analyzed using nonlinear regression analysis. Glucose metabolic rate (MR_glc) was calculated using Patlak linear regression analysis. The SUV_max of the lesions was determined on additional static PET/CT images. Results: Both MR_glc and SUV_max were significantly higher for hereditary cluster 1 (SDHx, VHL) tumors than for hereditary cluster 2 (RET, NF1) and sporadic tumors (P < 0.01 and P < 0.05, respectively). Median k ₃ was significantly higher for cluster 1 than for sporadic tumors (P < 0.01). Median V_b was significantly higher for cluster 1 than for cluster 2 tumors (P < 0.01). No statistically significant differences in K ₁ and k ₂ were found between the groups. Cutoffs for k ₃ to distinguish between cluster 1 and other tumors were established at 0.015 min^-1 (100% sensitivity, 15.8% specificity) and 0.636 min^-1 (100% specificity, 85.7% sensitivity). MR_glc significantly correlated with SUV_max (P = 0.001) and k ₃ (P = 0.002). Conclusion: In vivo metabolic tumor profiling in patients with PPGL can be achieved by assessing ¹⁸F-FDG pharmacokinetics using dynamic PET/CT scanning. Cluster 1 PPGLs can be reliably identified by a high ¹⁸F-FDG phosphorylation rate.

Distinctive FDG-PET/CT Findings in Acute Neurological Hospital Care

A compilation of 6 distinctive ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) combined with computed tomography (CT) findings in the acute setting of neurohospital care is presented. In case 1, PET/CT allowed the final diagnosis of circumscribed ischemic infarction by demonstrating a clear pattern of luxury perfusion. In case 2, diagnosis of thalamic abscess was made, whereby PET/CT demonstrated an empty zone. Hypermetabolic enlarged hilar lymph nodes and hypermetabolic spinal lumbar roots in PET/CT led to the diagnosis of neurosarcoidosis in case 3. In case 4, a hypermetabolic brain focus in PET/CT identified the seizure focus in epilepsia partialis continua. A cerebral hemispheric hypometabolism in PET/CT in case 5 supported the diagnosis of Creutzfeldt-Jakob disease, which initially mimicked acute stroke. In case 6, PET/CT detected infective endocarditis as a source of multiple cerebral ischemic lesions. In conclusion, PET/CT can contribute importantly to find the correct diagnosis in acute neurohospital patients.

Role of pre-transplant 18F-FDG PET/CT in predicting hepatocellular carcinoma recurrence after liver transplantation

The last two decades have seen a paradigm shift in the selection of patients with hepatocellular carcinoma (HCC) for liver transplantation. Microvascular invasion and differentiation have been the most significant factors affecting post-transplant recurrence; however, because of inherent disadvantages of pre-transplant biopsy, histological criteria never gained popularity. Recently, the selection criteria evolved from morphological to biological criteria, such as biomarkers and response to loco-regional therapy. With the introduction of multimodality imaging, combination of computed tomography with nuclear medicine imaging, particularly, 18F-fluorodeoxyglucose positron emission tomography fulfilled an unmet need and rapidly became a critical component of HCC management. This review article will focus on the use of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in the pre-transplant evaluation of HCC patients with special discussion on its ability to predict HCC recurrence after liver transplantation.

DNA repair capacity correlates with standardized uptake values from 18F-fluorodeoxyglucose positron emission tomography/CT in patients with advanced non-small-cell lung cancer

Objective

The DNA repair capacity (DRC) of tumor cells is an important contributor to resistance to radiation and platinum-based drugs. Because DRC may be affected by tumor cell metabolism, we measured DRC in lymphocytes from patients with non–small-cell lung cancer (NSCLC) and compared the findings with the maximum standardized uptake value (SUV_max) on¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) after (chemo)radiation therapy.

Methods

This study included 151 patients with stage IA-IV NSCLC who had FDG PET at a single institution and donated blood samples before chemotherapy. We assessed the correlation of DRC, measured in peripheral T lymphocytes by a host-cell reactivation assay with SUV_max and their associations with overall survival (OS) time by hazards ratios calculated with a Cox proportional hazards regression model.

Results

SUV_max of the primary tumor at diagnosis was inversely associated with lymphocyte DRC (r = −0.175, P = 0.032), particularly among patients with advanced disease (r = −0.218, P = 0.015). However, ΔSUV_max of primary tumor was not significantly associated with DRC (r = 0.005, P = 0.968). SUV_max of regional lymph nodes at diagnosis (r = −0.307, P = 0.0008) and after (chemo)radiation treatment (r = −0.329, P = 0.034) and SUV_max of the primary tumor after (chemo)radiation treatment (r = −0.253, P = 0.045) were also inversely associated with OS time.

Conclusion

DRC was inversely associated with primary tumor SUV_max before treatment but not with ΔSUV_max after (chemo)radiation.

SEOM-SERAM-SEMNIM guidelines on the use of functional and molecular imaging techniques in advanced non-small-cell lung cancer

Imaging in oncology is an essential tool for patient management but its potential is being profoundly underutilized. Each of the techniques used in the diagnostic process also conveys functional information that can be relevant in treatment decision-making. New imaging algorithms and techniques enhance our knowledge about the phenotype of the tumor and its potential response to different therapies. Functional imaging can be defined as the one that provides information beyond the purely morphological data, and include all the techniques that make it possible to measure specific physiological functions of the tumor, whereas molecular imaging would include techniques that allow us to measure metabolic changes. Functional and molecular techniques included in this document are based on multi-detector computed tomography (CT), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET), magnetic resonance imaging (MRI), and hybrid equipments, integrating PET with CT (PET/CT) or MRI (PET-MRI). Lung cancer is one of the most frequent and deadly tumors although survival is increasing thanks to advances in diagnostic methods and new treatments. This increased survival poises challenges in terms of proper follow-up and definitions of response and progression, as exemplified by immune therapy-related pseudoprogression. In this consensus document, the use of functional and molecular imaging techniques will be addressed to exploit their current potential and explore future applications in the diagnosis, evaluation of response and detection of recurrence of advanced NSCLC.

Clinical Significance of Fluorine-18-fluorodeoxyglucose Positron Emission Tomography/computed Tomography in the Follow-up of Colorectal Cancer: Searching off Approaches Increasing Specificity for Detection of Recurrence

Background

Nearly 40% of colorectal cancer (CRC) recurs within 2 years after resection of primary tumor. Imaging with fluorine-18-fluorodeoxyglucose (^l8F-FDG) positron emission tomography/computed tomography (PET/CT) is the most recent modality and often applied for the evaluation of metastatic spread during the follow-up period. Our goal was to study the diagnostic importance of ¹⁸F-FDG-PET/CT data of maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG) and the difference of SUVmax on dual-time imaging in CRC.

Patients and methods

We examined the SUVmax value of lesions on control or restaging ¹⁸F-FDG-PET/CT of 53 CRC patients. All lesions with increased SUVmax values were confirmed by colonoscopy or histopathology. We compared PET/CT results with conventional imaging modalities (CT, MRI) and tumor markers (carbohydrate antigen 19-9 [Ca 19-9], carcinoembryonic antigen [CEA]).

Results

Mean SUVmax was 6.9 ± 5.6 in benign group, 12.7 ± 6.1 in malignant group. Mean TLG values of malignant group and benign group were 401 and 148, respectively. ¹⁸F-FDG-PET/CT was truely positive in 48% of patients with normal Ca 19-9 or CEA levels and truely negative in 10% of cases with elevated Ca 19-9 or CEA. CT or MRI detected suspicious malignancy in 32% of the patients and ¹⁸F-FDG-PET/CT was truely negative in 35% of these cases. We found the most important and striking statistical difference of TLG value between the groups with benign and recurrent disease.

Conclusions

Although SUVmax is a strong metabolic parameter (p = 0.008), TLG seems to be the best predictor in recurrence of CRC (p = 0.001); both are increasing the specificity of ¹⁸F-FDG-PET/CT.

Regional 18F-Fluorodeoxyglucose Hypometabolism is Associated with Higher Apathy Scores Over Time in Early Alzheimer Disease

OBJECTIVES

Apathy is among the earliest and most pervasive neuropsychiatric symptoms in prodromal and mild Alzheimer disease (AD) dementia that correlates with functional impairment and disease progression. We investigated the association of apathy with regional 18F-fluorodeoxyglucose (FDG) metabolism in cognitively normal, mild cognitive impairment, and AD dementia subjects from the Alzheimer's Disease Neuroimaging Initiative database.

DESIGN

Cross-sectional and longitudinal studies.

SETTING

57 North American research sites.

PARTICIPANTS

402 community dwelling elders.

MEASUREMENTS

Apathy was assessed using the Neuropsychiatric Inventory Questionnaire. Baseline FDG metabolism in five regions implicated in the neurobiology of apathy and AD was investigated in relationship to apathy at baseline (cross-sectional general linear model) and longitudinally (mixed random/fixed effect model). Covariates included age, sex, diagnosis, apolipoprotein E genotype, premorbid intelligence, cognition, and antidepressant use.

RESULTS

Cross-sectional analysis revealed that posterior cingulate hypometabolism, diagnosis, male sex, and antidepressant use were associated with higher apathy scores. Longitudinal analysis revealed that the interaction of supramarginal hypometabolism and time, posterior cingulate hypometabolism, and antidepressant use were associated with higher apathy scores across time; only supramarginal hypometabolism was positively related to rate of increase of apathy.

CONCLUSIONS

Results support an association of apathy with hypometabolism in parietal regions commonly affected in early stages of AD, rather than medial frontal regions implicated in the neurobiology of apathy in later stages. Further work is needed to substantiate whether this localization is specific to apathy rather than to disease stage, and to investigate the potential role of AD proteinopathies in the pathogenesis of apathy.

A Prospective Study Comparing Functional Imaging (18F-FDG PET) Versus Anatomical Imaging (Contrast Enhanced CT) in Dosimetric Planning for Non-small Cell Lung Cancer

Objective(s):

¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET-CT) is a well-used and established technique for lung cancer staging. Radiation therapy requires accurate target volume delineation, which is difficult in most cases due to coexisting atelectasis. The present study was performed to compare the ¹⁸F-FDG PET-CT with contrast enhanced computed tomography (CECT) in target volume delineation and investigate their impacts on radiotherapy planning.

Methods:

Eighteen patients were subjected to ¹⁸F- FDG PET-CT and CECT in the same position. Subsequently, the target volumes were separately delineated on both image sets. In addition, the normal organ doses were compared and evaluated.

Results:

The comparison of the primary gross tumour volume (GTV) between the ¹⁸F-FDG PET-CT and CECT imaging revealed that 88.9% (16/18) of the patients had a quantitative change on the ¹⁸F-FDG PET-CT. Out of these patients, 77% (14/18) of the cases had a decrease in volume, while 11% (2/18) of them had an increase in volume on the ¹⁸F-FDG PET-CT. Additionally, 44.4% (8/18) of the patients showed a decrease by > 50 cm³ on the ¹⁸F-FDG PET-CT. The comparison of the GTV lymph node between the ¹⁸F-FDG PET-CT and CECT revealed that the volume changed in 89% (16/18) of the patients: it decreased and increased in 50% (9/18) and 39% (7/18) on the ¹⁸F-FDG PET-CT. New nodes were identified in 27% (5/18) of the patients on the ¹⁸F-FDG PET-CT. The decrease in the GTV lymph node on the ¹⁸F-FDG PET-CT was statistically significant. The decreased target volumes made radiotherapy planning easier with improved sparing of normal tissues.

Conclusion:

GTV may either increase or decrease with the ¹⁸F-FDG PET-CT, compared to the CECT. However, the ¹⁸F-FDG PET-CT-based contouring facilitates the accurate delineation of tumour volumes, especially at margins, and detection of new lymph node volumes. The non-FDG avid nodes can be omitted to avoid elective nodal irradiation, which can spare the organs at risk and improve accurate staging and treatment.

Lesson of the month 1: Large vessel vasculitis - a diagnostic challenge and the role of 18-fluorodeoxyglucose positron emission tomography

Large vessel vasculitis can pose a significant diagnostic challenge. It may be insidious in onset with the only presenting symptoms consisting of constitutional compromise. It may mimic other pathologies and the only serological abnormalities may be abnormal inflammatory markers. Conventional imaging modalities may not be diagnostic. We present a case of large vessel vasculitis that proved a significant diagnostic challenge with diagnosis established on 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) computerised tomography (CT) imaging. This is one of five cases of large vessel vasculitis that were diagnosed in the rheumatology department at our trust over a 12-month period with diagnosis established with the use of 18F-FDG PET CT. We discuss the advantages of 18F-FDG PET CT over more conventional imaging modalities in diagnosing large vessel vasculitis.