Vincent Dunet

Performance of 18F-Fluoro-Ethyl-Tyrosine (18F-FET) PET for the Differential Diagnosis of Primary Brain Tumor: A Systematic Review and Metaanalysis

For the past decade, PET with 18F-fluoro-ethyl-tyrosine (18F-FET) has been used in the evaluation of patients with primary brain tumors (PBTs), but so far series have reported only a limited number of patients. The purpose of this systematic review and metaanalysis was to assess the diagnostic performance of 18F-FET PET in patients with suspicion of PBT. Methods: We examined studies published in the literature using MEDLINE and EMBASE databases. Inclusion criteria were use of 18F-FET PET for initial assessment of patients with a newly diagnosed brain lesion; patients who had no radiotherapy, surgery, or chemotherapy before 18F-FET PET; and use of histology as a gold standard. Metaanalysis was performed on a per-patient basis. We secondarily performed receiver-operating-characteristic analysis of pooled patients to determine tumor-to-background ratio (TBR) of 18F-FET uptake and best diagnostic value. Results: Thirteen studies totaling 462 patients were included. For the diagnosis of PBT, 18F-FET PET demonstrated a pooled sensitivity of 0.82 (95% confidence interval [CI], 0.74–0.88), specificity of 0.76 (95% CI, 0.44–0.92), area under the curve of 0.84 (95% CI, 0.80–0.87), positive likelihood ratio of 3.4 (95% CI, 1.2–9.5), and negative likelihood ratio of 0.24 (95% CI, 0.14–0.39). Receiver-operating-characteristic analysis indicated that a mean TBR threshold of at least 1.6 and a maximum TBR of at least 2.1 had the best diagnostic value for differentiating PBTs from nontumoral lesions. Conclusion: 18F-FET PET demonstrated excellent performance for diagnosing PBTs. Strict standardization of PET acquisition protocols and prospective, multicenter studies investigating the added value over current MRI are now needed to establish 18F-FET PET as a highly relevant tool for patient management.

Added prognostic value of myocardial blood flow quantitation in rubidium-82 positron emission tomography imaging.

AIMS We studied the respective added value of the quantitative myocardial blood flow (MBF) and the myocardial flow reserve (MFR) as assessed with (82)Rb positron emission tomography (PET)/CT in predicting major adverse cardiovascular events (MACEs) in patients with suspected myocardial ischaemia. METHODS AND RESULTS Myocardial perfusion images were analysed semi-quantitatively (SDS, summed difference score) and quantitatively (MBF, MFR) in 351 patients. Follow-up was completed in 335 patients and annualized MACE (cardiac death, myocardial infarction, revascularization, or hospitalization for congestive heart failure or de novo stable angor) rates were analysed with the Kaplan-Meier method in 318 patients after excluding 17 patients with early revascularizations (<60 days). Independent predictors of MACEs were identified by multivariate analysis. During a median follow-up of 624 days (inter-quartile range 540-697), 35 MACEs occurred. An annualized MACE rate was higher in patients with ischaemia (SDS >2) (n = 105) than those without [14% (95% CI = 9.1-22%) vs. 4.5% (2.7-7.4%), P < 0.0001]. The lowest MFR tertile group (MFR <1.8) had the highest MACE rate [16% (11-25%) vs. 2.9% (1.2-7.0%) and 4.3% (2.1-9.0%), P < 0.0001]. Similarly, the lowest stress MBF tertile group (MBF <1.8 mL/min/g) had the highest MACE rate [14% (9.2-22%) vs. 7.3% (4.2-13%) and 1.8% (0.6-5.5%), P = 0.0005]. Quantitation with stress MBF or MFR had a significant independent prognostic power in addition to semi-quantitative findings. The largest added value was conferred by combining stress MBF to SDS. This holds true even for patients without ischaemia. CONCLUSION Perfusion findings in (82)Rb PET/CT are strong MACE outcome predictors. MBF quantification has an added value allowing further risk stratification in patients with normal and abnormal perfusion images.

Performance of 18F-FET versus 18F-FDG-PET for the diagnosis and grading of brain tumors: systematic review and meta-analysis

BACKGROUND For the past decade (18)F-fluoro-ethyl-l-tyrosine (FET) and (18)F-fluoro-deoxy-glucose (FDG) positron emission tomography (PET) have been used for the assessment of patients with brain tumor. However, direct comparison studies reported only limited numbers of patients. Our purpose was to compare the diagnostic performance of FET and FDG-PET. METHODS We examined studies published between January 1995 and January 2015 in the PubMed database. To be included the study should: (i) use FET and FDG-PET for the assessment of patients with isolated brain lesion and (ii) use histology as the gold standard. Analysis was performed on a per patient basis. Study quality was assessed with STARD and QUADAS criteria. RESULTS Five studies (119 patients) were included. For the diagnosis of brain tumor, FET-PET demonstrated a pooled sensitivity of 0.94 (95% CI: 0.79-0.98) and pooled specificity of 0.88 (95% CI: 0.37-0.99), with an area under the curve of 0.96 (95% CI: 0.94-0.97), a positive likelihood ratio (LR+) of 8.1 (95% CI: 0.8-80.6), and a negative likelihood ratio (LR-) of 0.07 (95% CI: 0.02-0.30), while FDG-PET demonstrated a sensitivity of 0.38 (95% CI: 0.27-0.50) and specificity of 0.86 (95% CI: 0.31-0.99), with an area under the curve of 0.40 (95% CI: 0.36-0.44), an LR+ of 2.7 (95% CI: 0.3-27.8), and an LR- of 0.72 (95% CI: 0.47-1.11). Target-to-background ratios of either FDG or FET, however, allow distinction between low- and high-grade gliomas (P > .11). CONCLUSIONS For brain tumor diagnosis, FET-PET performed much better than FDG and should be preferred when assessing a new isolated brain tumor. For glioma grading, however, both tracers showed similar performances.

Voriconazole-induced periostitis.

We report the case of a 42-year-old woman receiving voriconazole for a fungal endophthalmitis, who presented with diffuse and severe musculoskeletal pain after 4 months of therapy. In the absence of an obvious aetiology, the patient was referred for three-phase bone scintigraphy. The anterior wholebody scan acquired 20 min after injection showed multiple and intense linear-shaped foci throughout the skeleton affecting predominantly the diaphyses of the long bones (a), corresponding to increased tracer uptake in the cortical bone on the delayed anterior whole-body scan affecting the upper and lower limbs, clavicles, scapulas and ribs (b, c). In a recent case series of transplant recipients receiving long-term voriconazole therapy, a painful periostitis was associated with fluoride excess [1]. Wang et al. [2] reported a series of five patients with possibly drug-induced periostitis associated with voriconazole administration. These patients presented clinically with “secondary hypertrophic osteoarthropathy”, a syndrome usually characterized by digital clubbing, diffuse periostosis of the tubular bones and synovial effusions [3]. In our patient, a nodular periostitis and only a slight focal lamellar periosteal reaction around the radial and pretibial diaphyses were observed on review of the scintigraphy-guided conventional radiograph. As this severe adverse event was probably associated with voriconazole, therapy was promptly stopped. Five days after discontinuation, all clinical symptoms had resolved and the radiographic anomalies had decreased at the 4-month follow-up. This case report illustrates the key role of three-phase bone scintigraphy for the investigation of patients with atypical skeletal symptoms.

Liver and biliary damages following transarterial chemoembolization of hepatocellular carcinoma: comparison between drug-eluting beads and lipiodol emulsion

ObjectivesTo compare transarterial chemoembolization (TACE)-related hepatic toxicities of conventional TACE (cTACE) and drug-eluting beads TACE (DEB-TACE) in patients with intermediate-stage hepatocellular carcinoma.MethodsIn this retrospective study, 151 consecutive patients undergoing cTACE or DEB-TACE and MRI 3-6 weeks before and after therapy were included. Toxicity was assessed on imaging (global hepatic damages (GHD), overall biliary injuries, biliary cast, bile duct dilatation, intrahepatic biloma, portal thrombosis), and clinico-biological follow-ups. Tumour response, time to progression (TTP), and overall survival were assessed. Factors influencing complication rate were identified by generalized equation logistic regression model.ResultsBiliary injuries and intrahepatic biloma incidence were significantly higher following DEB-TACE (p < 0.001). DEB-TACE showed a significant increased risk of GHD (OR: 3.13 [1.74-5.63], p < 0.001) and biliary injuries (OR: 4.53 [2.37-8.67], p < 0.001). A significant relationship was found between baseline prothrombin value and GHD, biliary injuries and intrahepatic biloma (all p < 0.01), and between the dose of chemotherapy and intrahepatic biloma (p = 0.001). Only TTP was significantly shorter following DEB-TACE compared to cTACE (p = 0.025).ConclusionsDEB-TACE was associated with increased hepatic toxicities compared to cTACE. GHD, biliary injuries, and intrahepatic biloma were more frequently observed with high baseline prothrombin value, suggesting that cTACE might be more appropriate than DEB-TACE in patients with less advanced cirrhosis.Key points• DEB-TACE demonstrated more therapy-related hepatic locoregional complications compared to cTACE.• TACE-related hepatic locoregional toxicities occurred more frequently with high baseline PT value.• cTACE may be more appropriate in patients with high baseline PT value.

Diffusion-weighted magnetic resonance imaging in metastatic gastrointestinal stromal tumor (GIST): a pilot study on the assessment of treatment response in comparison with 18F-FDG PET/CT

Background Diffusion-weighted magnetic resonance imaging (MRI) is increasingly being used for assessing the treatment succes in oncology, but the real clinical value needs to evaluated by comparison with other, already established, metabolic imaging techniques. Purpose To prospectively evaluate the clinical potential of diffusion-weighted MRI with apparent diffusion coefficient (ADC) mapping for gastrointestinal stromal tumor (GIST) response to targeted therapy compared with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). Material and Methods Eight patients (mean age, 56 ± 11 years) known to have metastatic GIST underwent 18F-FDG PET/CT and MRI (T1Gd, DWI [b = 50,300,600], ADC mapping) simultaneously, before and after change in targeted therapy. MR and PET/CT examinations were first analyzed blindly. Second, PET/CT images were co-registered with T1Gd-MR images for lesion detection. Only 18F-FDG avid lesions were considered. Maximum standardized uptake value (SUVmax) and the corresponding minimum ADCmin were measured for the six largest lesions per patient, if any, on baseline and follow-up examinations. The relationship between changes in SUVmax and ADCmin was analyzed (Spearmans correlation). Results Twenty-four metastases (12 hepatic, 12 extra-hepatic) were compared on PET/CT and MR images. SUVmax decreased from 7.7 ± 8.1 g/mL to 5.5 ± 5.4 g/mL (P = 0.20), while ADCmin increased from 1.2 ± 0.3 × 10−3mm2/s to 1.5 ± 0.3 × 10−3mm2/s (P = 0.0002). There was a significant association between changes in SUVmax and ADCmin (rho = − 0.62, P = 0.0014), but not between changes in lesions size (P = 0.40). Conclusion Changes in ADCmin correlated with the response of 18F-FDG avid GIST to targeted therapy. Thus, diffusion-weighted MRI may represent a radiation-free alternative for follow-up treatment for metastatic GIST patients.

Incidental extracardiac findings on cardiac MR: Systematic review and meta-analysis

To perform a systematic review and meta‐analysis to calculate the pooled prevalence of incidental extracardiac findings (IEFs) on cardiac magnetic resonance (MR) and to determine factors influencing reported prevalences.

Chest CT at a dose below 0.3 mSv: impact of iterative reconstruction on image quality and lung analysis.

Background In chest computed tomography (CT), iterative reconstruction (IR) algorithms maintain diagnostic image quality (IQ) while significantly reducing the dose. Purpose To evaluate the impact of IR on IQ of chest CT at effective doses below 0.3 mSv. Material and Methods Twenty chest CT scans performed at effective dose below 0.3 mSv (CT1) were reconstructed varying three parameters: filtered back-projection and IR iDose4 algorithms; 512 × 512 and 768 × 768 matrices; and sharp and soft kernels, thus generating eight series per patient. The qualitative evaluation of the IQ was performed by ranking series from 1 to 8 (8 corresponding to the highest rank) which was subsequently compared to quantitative assessment of IQ by using an appropriated merit formula. Intra- and inter-reader IQ ranking reliability was also evaluated using Cohen’s kappa. Analysis of lung findings was finally compared between the best CT1 series and the reference CT (CT0). Results The best series in terms of qualitative and quantitative IQ was obtained using IR, 5122 matrix and soft kernel. The best CT1 series detected nodules greater than 4 mm with an almost perfect match with CT0. Conclusion Chest CT performed at effective doses below 0.3 mSv may be used to confidently diagnose lesions greater than 4 mm using iDose4, soft kernel and 512 × 512 matrix.

Bone Marrow Metastases: T2-weighted Dixon Spin-Echo Fat Images Can Replace T1-weighted Spin-Echo Images

Purpose To test the potential of Dixon T2-weighted fat-only sequences to replace T1-weighted sequences for the detection of bone metastases, with the hypothesis that diagnostic performance with an alternative magnetic resonance (MR) imaging protocol (sagittal spin-echo Dixon T2-weighted fat-only and water-only imaging) would not be inferior to that with the standard protocol (sagittal spin-echo T1-weighted and spin-echo Dixon T2-weighted water-only imaging). Materials and Methods A total of 121 consecutive whole-spine MR imaging examinations (63 men; mean age ± standard deviation, 61.4 years ± 11.8) performed for suspected vertebral bone metastases were included in this retrospective, institutional review board-approved study. Quantitative image analysis was performed for 30 randomly selected spine levels. Qualitative analysis was performed separately by two musculoskeletal radiologists, who registered the number of metastases for each spine level. Areas under the curve with the protocols were compared on the basis of nonparametric receiver operating characteristic curve estimations by using a noninferiority test on paired data, with a best valuable comparator as a reference. Interobserver and interprotocol agreement was assessed by using κ statistics. Results Contrast-to-noise ratio was significantly higher on the alternative protocol images than on the standard protocol images (181.1 [95% confidence interval: 140.4, 221.7] vs 84.7 [95% confidence interval: 66.3, 103.1] respectively; P < .001). Diagnostic performance was not significantly inferior with the alternative protocol than with the standard protocol for both readers in a per-patient analysis (sensitivity, 97.9%-98.9% vs 93.6%-97.9%; specificity, 85.2%-92.6% vs 92.6%-96.3%; area under the curve, 0.92-0.96 vs 0.95, respectively; all P ≤ .02) and a per-spine level analysis (all P < .01). Interobserver and interprotocol agreement was good to very good (κ = 0.70-0.81). Conclusion Dixon T2-weighted fat-only and water-only imaging provide, in one sequence, diagnostic performance similar to that of the standard combination of morphologic sequences for the detection of probable spinal bone metastases, thereby providing an opportunity to reduce imaging time by eliminating the need to perform T1 sequences.

Cognitive Impairment and Basal Ganglia Functional Connectivity in Vascular Parkinsonism

BACKGROUND AND PURPOSE: Patients with vascular parkinsonism have higher cognitive decline and more basal ganglia lesions. We aimed to evaluate the relationship of cognitive impairment with functional connectivity between the basal ganglia and cingulate cortex in vascular parkinsonism. MATERIALS AND METHODS: Thirty patients (8 with vascular parkinsonism and 22 with Parkinson disease) and 23 controls were enrolled. The Mattis Dementia Rating Scale and the Stroop Task were used to assess cognitive decline. MR imaging examinations included T1-MPRAGE, FLAIR, and resting-state fMRI sequences. MPRAGE was segmented to obtain basal ganglia and cingulate cortex volumes. FLAIR was segmented to obtain white matter hyperintensity lesion volume. Resting-state fMRI sequences were used to compare basal ganglia functional connectivity with the cingulate cortex between patients and controls. RESULTS: Patients with vascular parkinsonism exhibited impaired attention, resistance to interference, and inhibitory control and an increased number of errors on the Stroop Task. They also had higher caudate nucleus and white matter hyperintensity lesion volumes, which were positively correlated (ρ = 0.75, P < .0001). Caudate nucleus functional connectivity with the perigenual anterior cingulate cortex was increased in patients with vascular parkinsonism compared with controls and patients with Parkinson disease, and it was positively correlated with the caudate nucleus volume (ρ = 0.44, P = .016). Caudate nucleus functional connectivity with the posterior cingulate cortex was decreased in patients with vascular parkinsonism compared with controls and negatively correlated with the number of errors on the Stroop test (ρ = −0.51, P = .0003). CONCLUSIONS: In patients with vascular parkinsonism, cognitive decline could be related to changes of caudate nucleus functional connectivity with the cingulate cortex at resting-state, which may be induced by ischemia-related remodelling.