R. Chequer

Respective Performance of 18F-FDG-PET and Radiolabeled Leukocyte Scintigraphy for the Diagnosis of Prosthetic Valve Endocarditis

Echocardiography plays a key role in the diagnosis of infective endocarditis (IE) but can be inconclusive in patients in whom prosthetic valve endocarditis (PVE) is suspected. The incremental diagnostic value of 18F-FDG PET and radiolabeled leukocyte scintigraphy in IE patients has already been reported. The aim of this study was to compare the respective performance of 18F-FDG PET and leukocyte scintigraphy for the diagnosis of PVE in 39 patients. Methods: 18F-FDG PET and leukocyte scintigraphy were performed on 39 consecutive patients admitted because of clinically suspected PVE and inconclusive echocardiography results. The results of 18F-FDG PET and leukocyte scintigraphy were analyzed separately and retrospectively by experienced physicians masked to the results of the other imaging technique and to patient outcome. The final Duke–Li IE classification was made after a 3-mo follow-up. Results: Of the 39 patients, 14 were classified as having definite IE, 4 as having possible IE, and 21 as not having IE. The average interval between 18F-FDG PET and leukocyte scintigraphy was 7 ± 7 d. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 93%, 71%, 68%, 94%, and 80%, respectively, for 18F-FDG PET and 64%, 100%, 100%, 81%, and 86%, respectively, for leukocyte scintigraphy. Discrepancies between the results of 18F-FDG PET and leukocyte scintigraphy occurred in 12 patients (31%). In patients with definite IE, 5 had true-positive 18F-FDG PET results but false-negative leukocyte scintigraphy results. Of these 5 patients, 3 had nonpyogenic microorganism IE (Coxiella or Candida). Of patients for whom endocarditis had been excluded, 6 had true-negative leukocyte scintigraphy results but false-positive 18F-FDG PET results. These 6 patients had been imaged in the first 2 mo after the last cardiac surgery. The last patient with a discrepancy between 18F-FDG PET and leukocyte scintigraphy was classified as having possible endocarditis and had positive 18F-FDG PET results and negative leukocyte scintigraphy results. Conclusion: 18F-FDG PET offers high sensitivity for the detection of active infection in patients with suspected PVE and inconclusive echocardiography results. Leukocyte scintigraphy offers a higher specificity, however, than 18F-FDG PET for diagnosis of IE and should be considered in cases of inconclusive 18F-FDG PET findings or in the first 2 mo after cardiac surgery.

Multi-modality imaging in cardiac ATTR amyloidosis: agreement between echocardiography, MRI and DPD-scintigraphy

Methods Seventy seven consecutive patients with multimodality imaging evaluation (echocardiography, 1.5T MRI and 99mTc-DPD scintigraphy) to diagnose cardiac amyloidosis were identified from the database of the French National Reference Center for Amyloidosis. Patients with pacemaker or severe renal failure did not undergo cardiac MRI and were analyzed on the basis of the echocardiography and scintigraphy (n=17). Three groups were compared: patients with positive agreement to diagnose cardiac ATTR (PA-ATTR group), patients with positive agreement to exclude cardiac ATTR (PA-normal) and patients with negative agreement (NA).

Comparison of MIBG and Diphosphonate scintigraphy in cardiac involvement of aTTR-FAP

Background In familial aTTR amyloid polyneuropathy (FAP) cardiac involvement is of major prognostic value. Two approaches using radionuclide imaging proved relevant in the assessment of aTTR-related cardiac amyloidosis: detection of amyloid deposits with disphosphonates (DPD) and of sympathetic denervation with MIBG. The study aimed to compare the respective value of both approaches in patients with aTTR-FAP with suspected cardiac involvement.

Disphosphonates cardiac uptake in familial amyloid neuropathy: Comparison between DPD and HMDP

Background Familial amyloid polyneuropathy (FAP) is a severe hereditary disease, due to production by the liver of a genetic variant transthyretin (TTR) resulting in tissue amyloid deposits. Cardiac involvement is of major prognostic value. Diphosphonate scintigraphy has been proposed as a diagnostic tool for TTR-related cardiac amyloidosis, but there is no consensus on the optimal radiopharmaceutical. Consequently, we compared the cardiac uptake of two 99mTc-labelled tracers: diphosphono-propanedicarboxylic acid (DPD) and hydroxymethylene diphosphonate (HMDP) in patients with TTR-FAP.

0079: Respective performances of FDG-PET and radiolabeled leukocyte scintigraphy for the diagnostic of prosthetic valve endocarditis

Purpose The incremental diagnostic value of 18-fluorodeoxyglucose positron emission tomography (FDG-PET) and radiolabeled leukocyte scintigraphy (LS) has already been reported in infective endocarditis (IE) patients. The aim of this study was to compare the respective performances of FDG-PET and LS for the diagnosis of prosthetic valve (PVE)-IE in 39 patients. Methods FDG-PET and LS were performed in 39 consecutive patients admitted for a clinical suspicion of PVE and inconclusive echocardiography who underwent both FDG-PET and LS. FDG-PET and LS were analysed separately and retrospectively by experienced physicians blinded to the results of the other imaging technique and to patient’s outcome. Final Duke-Li IE classification was performed after a 3-month follow-up period. Results Out of the 39 patients, 15 patients were classified after a 3-month follow-up period as definite IE, 3 as possible IE and 21 as excluded IE. Average time interval between FDG-PET and LS acquisitions was 7±7 days. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 93%, 71%, 70%, 94% and 81% for FDG-PET and 60%, 100%, 100%, 78% and 83% for LS, respectively. Discrepancies between the results of FDG-PET and LS occurred in 12 patients (31%). In patients with definite IE, 5 were identified with true positive FDG-PET but false negative LS. Out of these 5 patients, 3 presented non-pyogenic microorganism IE (Coxiella or Candida). In patients with excluded endocarditis, 6 patients were identified with true negative LS but false positive FDG-PET. These 6 patients had been imaged in the first two months following the last cardiac surgery. Conclusions FDG-PET offers a high sensitivity for the detection of active infection in patients with a suspicion of PVE. LS offers a higher specificity than FDG-PET for IE diagnosis and should be considered in case of inconclusive FDG-PET findings or in the first two months after cardiac surgery.

Quelles nouveautés en scintigraphie cardiaque

Le cardiologue a besoin pour l’identification et le suivi de patients coronariens de techniques d’imagerie non invasive performantes pour detecter la presence d’une ischemie myocardique. Durant les 15 dernieres annees, la qualite des acquisitions et les performances diagnostiques de la scintigraphie cardiaque sont restees inchangees, pendant que celles du coroscanner et de l’IRM cardiaque se sont tres nettement ameliorees. Toutefois, cette situation est en train de changer : de nouvelles technologies deviennent actuellement disponibles pour la realisation de scintigraphies cardiaques, ce qui devrait ameliorer les performances diagnostiques et diminuer le niveau d’irradiation associe a cet examen. Cet article presente les dernieres innovations en scintigraphie pour la detection de l’ischemie myocardique.

Quoi de neuf en cardiologie nucléaire

Depuis deux a trois ans, des progres technologiques tres importants sont survenus en cardiologie nucleaire. Ces innovations concernent a la fois l’imagerie en coupe monophotonique (SPECT), avec l’apparition d’un nouveau type de detecteurs bouleversant les performances des gamma-cameras conventionnelles (ou cameras d’Anger), et la tomographie par emission de positons (TEP-CT), avec l’arrivee tres prochaine en France de nouveaux traceurs de perfusion, associee a des cameras TEP ultrasensibles (« temps de vol »). Pour les deux techniques, l’association de la scintigraphie de perfusion et du coroscanner dans une imagerie « hybride » est egalement une donnee recente. Enfin, l’imagerie moleculaire se developpe en cardiologie, avec de nouveaux traceurs dont l’evaluation est deja tres avancee, actuellement en phase II ou III, tels que l’annexine V marquee au 99mtechnetium pour l’imagerie de la necrose et de l’apoptose myocytaire et l’activation plaquettaire, ou le 18FML10 (Earlytest®), nouveau radio-traceur pour la tomographie par emission de positons (TEP) se fixant dans les cellules apoptotiques. Nous envisagerons successivement ces differentes avancees.