Left ventricle function assessment using gated first-pass 18F-FDG PET: Validation against equilibrium radionuclide angiography.

PURPOSE: We appraised the feasibility of left ventricle (LV) function assessment using gated first-pass 18F-FDG PET, and assessed the concordance of the produced measurements with equilibrium radionuclide angiography (ERNA). MATERIALS AND METHODS: Twenty-four oncologic patients benefited from 99mTc-labeled red-blood-cell ERNA, in planar mode (all patients) and using SPECT (22 patients). All patients underwent gated first-pass 18F-FDG cardiac PET. Gated dynamic PET images were reconstructed over 1 minute during tracer first-pass inside the LV and post-processed using in-house software (TomPool). After re-orientation into cardiac canonical axes and adjustment of the valves plane using a phase image, pseudo-planar PET images obtained by re-projection were automatically segmented using thresholded region growing and gradient-based delineation to produce an LV ejection fraction (EF) estimate. PET images were also post-processed in fully-tomographic mode to produce LV end diastole volume (EDV), end systole volume (ESV), and EF estimates. Concordance was assessed using Lin's concordance (ccc) and Bland-Altman analysis. Reproducibility was assessed using the coefficient of variation (CoV) and intra-class correlation (ICC). RESULTS: Pseudo-planar PET EF estimates were concordant with planar ERNA (ccc = 0.81, P < .001) with a bias of 0% (95% CI [- 2%; 3%], limits of agreement [- 11%; 12%]). Reproducibility was excellent and similar for both methods (CoV = 2 ± 1% and 3 ± 2%, P = NS; ICC = 0.97 and 0.92, for PET and ERNA, respectively). Measurements obtained in fully-tomographic mode were concordant with SPECT ERNA: ccc = 0.83 and bias = - 3 mL for LV EDV, ccc = 0.92 and bias = 0 mL for LV ESV, ccc = 0.89 and bias = - 1% for LV EF (all P values < .001 for ccc, all biases not significant). CONCLUSIONS: Gated first-pass 18F-FDG PET might stand as a relevant alternative to ERNA for LV function assessment, enabling a joint evaluation of both therapeutic response and cardiac toxicity in oncologic patients receiving cardiotoxic chemotherapy.

Assessment of the area at risk after acute myocardial infarction using 123I-MIBG SPECT: Comparison with the angiographic APPROACH-score.

BACKGROUND: Assessment of the area at risk (AAR) associated with an acute myocardial infarction is crucial for evaluating prevention and revascularization strategies. The aim of this study was to evaluate whether 123I-metaiodobenzylguanidine (123I-MIBG) single-photon emission computed tomography (SPECT) provides a more widely available assessment of anatomical AAR than the established anatomical angiographic methods. METHODS: Seventy patients with ST-segment elevation acute myocardial infarction (STEMI) underwent coronary angiography with percutaneous coronary intervention and subsequent 123I-MIBG myocardial scintigraphy with left myocardial relative radiotracer uptake evaluation 12 ± 10 days after STEMI. Patients were divided into two groups depending on whether the culprit artery was occluded (50 patients) or sub-occluded (20 patients). Two scores were calculated as a percentage of the left ventricular myocardium surface, the first using a standard 17-segment summed rest score derived from the relative quantitative evaluation of 123I-MIBG myocardial uptake (MAR) and the second using the modified APPROACH-score (ApAR). RESULTS: For the patients with occluded artery, this study showed a high correlation between MAR and the angiographic score (Pearson r = .762 and P < .0001). For the patients with sub-occluded artery, for which the ApAR is not reliable, this study showed no correlation between MAR and the angiographic score (Pearson r = .18 and P = 0.45). CONCLUSIONS: 123I-MIBG myocardial scintigraphy provides ARR assessment similar to that of ApAR in patients with a single occluded coronary artery. However, MAR differs from ApAR when angiographic scores are known to be inaccurate (sub-occluded culprit artery) or impossible to use. Further studies are needed to evaluate the potential clinical interest of 123I-MIBG SPECT as an alternative for area at risk assessment after STEMI even when the culprit artery is sub-occluded or when the angiographic scores cannot be used.

Improving multi-pinhole CZT myocardial perfusion imaging specificity without changing sensibility by using adapted filter parameters.

BACKGROUND: Meta-analysis show the diagnostic performance of cardiac dedicated multi-pinhole cadmium-zinc-telluride myocardial perfusion imaging (MPI) with a sensibility around 0.9 and a specificity around 0.7. The aim of the present study is to explore a simple method to generate less artefact on MPI using single photon emission computed tomography (SPECT) and to enhance specificity without changing sensibility. RESULTS: From October 2018 to March 2019, 200 patients who underwent SPECT with [99mTc]Tc-tetrofosmin were prospectively recruited: 100 patients with ischemia or necrosis diagnosis (first arm), and 100 patients with myocardial reversible SPECT artefact (second arm). Each SPECT was explored using two image process based on a Butterworth prefilter and post-filter: the original image processing (reconstruction A) with a cut-off frequency equals to 37% of the Nyquist frequency and order equals to 7, and a second image processing (reconstruction B) with a cut-off frequency equals to 25% of the Nyquist frequency and order equals to 5. For each patient, sum stress or rest score with and without septum (SSRS and SSRSws) were calculated with the two reconstructions. No significant statistical difference between SSRSa and SSRSb was identified for the first arm (P = 0.54) and the relative difference ∆r was - 0.5 ± 11.1% (95% CI - 2.7 to 1.7). We found a significant statistical difference between SSRSa and SSRSb for the second arm (p < 0.0001) and the relative difference ∆r was 69.7 ± 16.2% (95% CI 66.6-72.9). CONCLUSION: In conclusion, using a Butterworth prefilter and post-filter cut-off frequency equal to 25% of the Nyquist frequency before iterative reconstruction generates less artefact and improves myocardial SPECT specificity without affecting sensibility compared with the original reconstruction.

Specific Effects of Anorexia Nervosa and Obesity on Bone Mineral Density and Bone Turnover in Young Women.

OBJECTIVE: The threefold aim was to (1) compare areal bone mineral density (aBMD), bone turnover markers, and periostin levels in young women with either anorexia nervosa (AN) or obesity (OB) and controls (CON); (2) model the profiles according to age; and (3) determine the parameters associated with aBMD. SUBJECTS AND METHODS: One hundred and fifty-two young women with ages ranging from 16.0 to 27.0 years were subdivided into 3 groups (AN, OB, CON). The CON group was age-matched by ±6 months. aBMD, bone turnover markers, and periostin levels were evaluated. RESULTS: aBMD modeling showed that hip aBMD was higher in OB than in the other 2 groups from 19 years, and AN presented lower values than CON from 21 years. aBMD at the lumbar spine was higher in older OB and CON women, starting from 20 to 22 years, but in AN the difference with the other 2 groups increased with age. Periostin levels were lower in OB than in AN or CON, but no variation with age was observed. Compared with controls, OB and AN presented similarly lower markers of bone formation, although markers of bone resorption were lower in OB and higher in AN. A modeling approach showed that markers of bone formation and resorption were lower in older than in younger CON, whereas the values of these bone markers remained relatively constant in AN and OB. In all groups, lean body mass (LBM) was the parameter most positively correlated with aBMD. CONCLUSION: This study demonstrated that weight extremes (AN or OB) influence aBMD, bone remodeling and periostin profiles. Moreover, factors related to aBMD were specific to each condition, but LBM was the parameter most consistently associated with aBMD.

Diagnostic and prognostic value of amyloid PET textural and shape features: comparison with classical semi-quantitative rating in 760 patients from the ADNI-2 database.

We evaluated the performance of amyloid PET textural and shape features in discriminating normal and Alzheimer's disease (AD) subjects, and in predicting conversion to AD in subjects with mild cognitive impairment (MCI) or significant memory concern (SMC). Subjects from the Alzheimer's Disease Neuroimaging Initiative with available baseline 18F-florbetapir and T1-MRI scans were included. The cross-sectional cohort consisted of 181 controls and 148 AD subjects. The longitudinal cohort consisted of 431 SMC/MCI subjects, 85 of whom converted to AD during follow-up. PET images were normalized to MNI space and post-processed using in-house software. Relative retention indices (SUVr) were computed with respect to pontine, cerebellar, and composite reference regions. Several textural and shape features were extracted then combined using a support vector machine (SVM) to build a predictive model of AD conversion. Diagnostic and prognostic performance was evaluated using ROC analysis and survival analysis with the Cox proportional hazard model. The three SUVr and all the tested features effectively discriminated AD subjects in cross-sectional analysis (all p < 0.001). In longitudinal analysis, the variables with the highest prognostic value were composite SUVr (AUC 0.86; accuracy 81%), skewness (0.87; 83%), local minima (0.85; 79%), Geary's index (0.86; 81%), gradient norm maximal argument (0.83; 82%), and the SVM model (0.91; 86%). The adjusted hazard ratio for AD conversion was 5.5 for the SVM model, compared with 4.0, 2.6, and 3.8 for cerebellar, pontine and composite SUVr (all p < 0.001), indicating that appropriate amyloid textural and shape features predict conversion to AD with at least as good accuracy as classical SUVr.

Comparative assessment of linear least-squares, nonlinear least-squares, and Patlak graphical method for regional and local quantitative tracer kinetic modeling in cerebral dynamic 18 F-FDG PET.

PURPOSE: Dynamic 18 F-FDG PET allows quantitative estimation of cerebral glucose metabolism both at the regional and local (voxel) level. Although sensitive to noise and highly computationally expensive, nonlinear least-squares (NLS) optimization stands as the reference approach for the estimation of the kinetic model parameters. Nevertheless, faster techniques, including linear least-squares (LLS) and Patlak graphical method, have been proposed to deal with high resolution noisy data, representing a more adaptable solution for routine clinical implementation. Former research investigating the relative performance of the available algorithms lack precise evaluation of kinetic parameter estimates under realistic acquisition conditions. METHODS: The present study aims at the systematic comparison of the feasibility and pertinence of kinetic modeling of dynamic cerebral 18 F-FDG PET using NLS, LLS, and Patlak method, based on numerical simulations and patient data. Numerical simulations were used to study the bias and variance of K1 and Ki parameters estimation under representative noise levels. Patient data allowed to assess the concordance between the three methods at the regional and voxel scale, and to evaluate the robustness of the estimations with respect to patient head motion. RESULTS AND CONCLUSIONS: Our findings indicate that at the regional level NLS and LLS provide kinetic parameter estimates (K1 and Ki ) with similar bias and variance characteristics (K1 bias ± relative standard deviation [RSD] 0.0 ± 5.1% and 0.1% ± 4.9% for NLS and LLS respectively, Ki bias ± RSD 0.1% ± 4.5% and -0.7% ± 4.4% for NLS and LLS respectively). NLS estimates appear, however, to be slightly less sensitive to patient motion. At the voxel level, provided that patient motion is negligible or corrected, LLS offers an appealing alternative solution for local K1 mapping. It yields K1 estimates that are highly correlated, with high correlation with NLS values (Pearson's r = 0.95 on actual data) within computations times less than two orders of magnitude lower. Last, Patlak method appears as the most robust and accurate technique for the estimation of Ki values at the regional and voxel scale, with or without head motion. It provides low bias/low variance Ki quantification (bias ± RSD -1.5 ± 9.5% and -4.1 ± 19.7% for Patlak and NLS respectively) as well as smooth parametric images suitable for visual assessment.

Therapeutic Response to Rituximab in IgG4-Related Hypophysitis Evidenced on 18F-FDG PET and MRI.

Baseline F-FDG PET and MRI were performed in a patient with IgG4-related hypophysitis, showing a 15-mm hypervascular hypermetabolic lesion with sellar and suprasellar extension. Lack of response after 10 months of first-line corticosteroid therapy was demonstrated on both F-FDG PET and MRI. Three months later, after 2 injections of 1 g of rituximab associated with continued corticosteroid therapy, MRI showed substantial shrinkage of the pituitary lesion with minimal residual Gd enhancement, whereas F-FDG PET evidenced complete metabolic response. As such, joint F-FDG PET and MRI assessment during therapy may have a potential interest for treatment response evaluation in pituitary IgG4-related disease.

Diagnostic performance of 18F-FDG PET-CT for large vessel involvement assessment in patients with suspected giant cell arteritis and negative temporal artery biopsy.

OBJECTIVE: The purpose of our study was to assess the diagnostic performance of 18F-FDG PET-CT for large vessel involvement in patients with suspected giant cells arteritis (GCA) and a negative temporal artery biopsy (TAB). METHODS: We conducted a retrospective study in a cohort of patients with suspected GCA and negative TAB who underwent an 18F-FDG PET-CT. Ten vascular segments were studied using a visual score and a semi-quantitative method based on SUVmax ratio with respect to liver uptake. The diagnosis of GCA was established during a mean follow-up of 42 months, based on the presence of clinical symptoms, laboratory results, and imaging data compatible with GCA, good response to corticosteroid therapy, and no differential diagnosis after a follow-up of at least 18 months. RESULTS: We included 63 patients (30 men and 33 women, aged 67 ± 12 years). 18F-FDG PET-CT showed large vessel involvement in 22 patients, 14 of whom were finally diagnosed with GCA. Forty-one patients were 18F-FDG PET-CT negative, 9 of whom were finally diagnosed with GCA. Overall, 18F-FDG uptake by large vessel yielded 61% sensitivity, 80% specificity, 64% positive predictive value, 78% negative predictive value, and 73% diagnostic accuracy. A significant number of patients were treated by corticosteroids before 18F-FDG PET-CT. However, corticosteroid therapy did not impact significantly the diagnostic performance, although there was a trend to a lower sensitivity in patients receiving corticosteroid therapy for more than 3 days. CONCLUSIONS: 18F-FDG PET-CT is a useful imaging technique to assess large vessel involvement in patients with suspected GCA and negative TAB.

Evidence of Subclavian Vein Thrombosis on First-Pass 18FDG PET in a Patient with Relapsing Upper Mediastinum Lymphoma.

Baseline 18F-FDG PET was performed in a 74-year-old patient with relapsing upper mediastinum lymphoma. Left subclavian thrombosis was suspected on prior contrast-enhanced CT. Dynamic PET imaging was achieved during 3 min after IV injection of 18F-FDG to the left arm in order to further assess left subclavian vein permeability. The 20-s dynamic frame at 1 min after injection confirmed the absence of flow in the left subclavian vein and evidenced the derivation of 18F-FDG through left axillary, then superficial, then right internal mammary collaterals to the superior vena cava, hence confirming the subclavian thrombosis.

Pineal Anaplastic Ependymoma With Multifocal Intradural Extramedullary Metastases on MRI and 18FDG-PET.

A 49-year-old woman presented to the emergency room with subacute paraparesis associated with bilateral cervicobrachial neuralgia. Brain and spine MRI revealed a heterogeneous hypervascular pineal tumor and a multifocal thoracolumbar intradural-extramedullary infiltrate with signs of medullary compression. C7-T2 laminectomy was performed on the same day for medullary decompression, allowing for partial lesion excision. Histological examination was in favor of a poorly differentiated anaplastic ependymoma. Two weeks later, FDG-PET showed markedly increased uptake in the pineal mass and significant hypermetabolism of the spinal metastases.

Area at risk can be assessed by iodine-123-meta-iodobenzylguanidine single-photon emission computed tomography after myocardial infarction: a prospective study.

BACKGROUND: Myocardial salvage is an important surrogate endpoint to estimate the impact of treatments in patients with ST-segment elevation myocardial infarction (STEMI). AIM: The aim of this study was to evaluate the correlation between cardiac sympathetic denervation area assessed by single-photon emission computed tomography (SPECT) using iodine-123-meta-iodobenzylguanidine (I-MIBG) and myocardial area at risk (AAR) assessed by cardiac magnetic resonance (CMR) (gold standard). PATIENTS AND METHODS: A total of 35 postprimary reperfusion STEMI patients were enrolled prospectively to undergo SPECT using I-MIBG (evaluates cardiac sympathetic denervation) and thallium-201 (evaluates myocardial necrosis), and to undergo CMR imaging using T2-weighted spin-echo turbo inversion recovery for AAR and postgadolinium T1-weighted phase sensitive inversion recovery for scar assessment. RESULTS: I-MIBG imaging showed a wider denervated area (51.1±16.0% of left ventricular area) in comparison with the necrosis area on thallium-201 imaging (16.1±14.4% of left ventricular area, P<0.0001). CMR and SPECT provided similar evaluation of the transmural necrosis (P=0.10) with a good correlation (R=0.86, P<0.0001). AAR on CMR was not different compared with the denervated area (P=0.23) and was adequately correlated (R=0.56, P=0.0002). Myocardial salvage evaluated by SPECT imaging (mismatch denervated but viable myocardium) was significantly higher than by CMR (P=0.02). CONCLUSION: In patients with STEMI, I-MIBG SPECT, assessing cardiac sympathetic denervation may precisely evaluate the AAR, providing an alternative to CMR for AAR assessment.

Association between textural and morphological tumor indices on baseline PET-CT and early metabolic response on interim PET-CT in bulky malignant lymphomas.

PURPOSE: We investigated whether metabolic, textural, and morphological tumoral indices evaluated on baseline PET-CT were predictive of early metabolic response on interim PET-CT in a cohort of patients with bulky Hodgkin and non-Hodgkin malignant lymphomas. METHODS: This retrospective study included 57 patients referred for initial PET-CT examination. In-house dedicated software was used to delineate tumor contours using a fixed 30% threshold of SUV max and then to compute tumoral metabolic parameters (SUV max, mean, peak, standard deviation, skewness and kurtosis, metabolic tumoral volume (MTV), total lesion glycolysis, and area under the curve of the cumulative histogram), textural parameters (Moran's and Geary's indices, energy, entropy, contrast, correlation derived from the gray-level co-occurrence matrix, area under the curve of the power spectral density, auto-correlation distance, and granularity), and shape parameters (surface, asphericity, convexity, surfacic extension, and 2D and 3D fractal dimensions). Early metabolic response was assessed on interim PET-CT using the Deauville 5-point scale and patients were ranked according to the Lugano classification as complete or not complete metabolic responders. The impact of the segmentation method (alternate threshold at 41%) and image resolution (Gaussian postsmoothing of 3, 5, and 7 mm) was investigated. The association of the proposed parameters with early response was assessed in univariate and multivariate analyses. Their added predictive value was explored using supervised classification by support vector machines (SVM). We evaluated in leave-one-out cross-validation three SVMs admitting as input features (a) MTV, (b) MTV + histological type, and (c) MTV + histology + relevant texture/shape indices. RESULTS: Features associated with complete metabolic response were low MTV (P = 0.01), low TLG (P = 0.003), high power spectral density AUC (P = 0.007), high surfacic extension (P = 0.006), low 2D fractal dimension (P = 0.007), and low 3D fractal dimension (P = 0.003). The prognostic value of these metrics was optimal with the 30% segmentation threshold and overall was progressively altered with decreasing image resolution. In cross-validation, the SVM accounting for texture and shape achieved the highest predictive value with ROC AUC of 0.82 and 80% accuracy (compared with 0.68 and 61% for MTV, and 0.65 and 68% for MTV + histology). CONCLUSIONS: The combination of usual prognostic factors with appropriately chosen textural and shape parameters evaluated on baseline PET-CT improves the prediction of early metabolic response in bulky lymphoma.