Cyrille Blondet

Pinhole SPECT imaging: compact projection/backprojection operator for efficient algebraic reconstruction

We describe the efficient algebraic reconstruction (EAR) method, which applies to cone-beam tomographic reconstruction problems with a circular symmetry. Three independant steps/stages are presented, which use two symmetries and a factorization of the point spread functions (PSFs), each reducing computing times and eventually storage in memory or hard drive. In the case of pinhole single photon emission computed tomography (SPECT), we show how the EAR method can incorporate most of the physical and geometrical effects which change the PSF compared to the Dirac function assumed in analytical methods, thus showing improvements on reconstructed images. We also compare results obtained by the EAR method with a cubic grid implementation of an algebraic method and modeling of the PSF and we show that there is no significant loss of quality, despite the use of a noncubic grid for voxels in the EAR method. Data from a phantom, reconstructed with the EAR method, demonstrate 1.08-mm spatial tomographic resolution despite the use of a 1.5-mm pinhole SPECT device and several applications in rat and mouse imaging are shown. Finally, we discuss the conditions of application of the method when symmetries are broken, by considering the different parameters of the calibration and nonsymmetric physical effects such as attenuation.

Impact of Malignancies in the Early and Late Time Course of Takotsubo Cardiomyopathy

BACKGROUND Although the relationship between malignancies and catecholamine-induced myocardial stunning remains largely speculative, it has been suggested that the presence of cancer may lower the threshold for stress stimuli and/or may aggravate cardiac adrenoreceptor sensitivity. We sought to investigate whether associations exist between a previous or current diagnosis of malignancy, diagnostic parameters during hospitalization and death in takotsubo. METHODSANDRESULTS The 154 takotsubo patients were retrospectively identified between May 2008 and December 2014. Previous history of malignancy was identified in 44 patients (28.5%). Cardiac arrest was present at admission in 13 patients (8.4%). Intra-aortic balloon pump was inserted in 16 patients (10.4%). In patients with malignancy, higher B-type natriuretic peptide (BNP), leukocyte and C-reactive protein (CRP) peaks could be observed during the hospital phase. Initial impairment of left ventricular ejection fraction was negatively related to BNP, leukocyte, and CRP peaks. At a median follow-up of 364 days, all-cause death occurred in 41 patients (26.6%) and cardiac death in 12 patients (7.7%). Multivariate Cox regression analysis identified malignancy (hazard ratio 4.77 (1.02-22.17), leukocyte peak and age as independent predictors of cardiac death. Malignancy (2.62 (1.26-5.44), leukocyte peak (1.05 (1.01-1.08) and initial cardiac arrest (6.68 (2.47-18.01) were identified as independent predictors of overall mortality. CONCLUSIONS In the present takotsubo patients, the prevalence of malignancy was high and may have affected cardiovascular outcomes through the activation of inflammatory and neurohormonal mechanisms. (Circ J 2016; 80: 2192-2198).

Unusual abdominal localization of cat scratch disease mimicking malignancy on F-18 FDG PET/CT examination.

Abstract: Because of its high diagnostic sensitivity in detection of unknown primary tumors, F-18 FDG PET/CT was used in the exploration of a 51-year-old woman presenting with multiple lymphadenopathy of the hepatic hilum and several hepatic and splenic hypodensities on radiologic examinations for which malignancy was suspected. Despite the morphofunctional malignant appearance, both histologic examination and PCR analysis revealed Bartonella henselae infection. Moreover, repeat F-18 FDG PET showed disease regression during focused antibiotic therapy.

FDG PET findings of the brain in sudden blindness caused by bilateral central retinal artery occlusion revealing giant cell arteritis.

We report the case of a 73-year-old woman presenting sudden blindness caused by bilateral simultaneous central retinal artery occlusion revealed by ophthalmoscopy. Temporal artery biopsy confirmed the giant cell arteritis. The patient was treated with a systemic steroid without visual recovery. FDG PET/CT was performed 6 months later in the context of persistent inflammatory syndrome. This case shows the close relationship between functional activity and glucose energy metabolism. We observed both bilateral occipital hypometabolism corresponding to loss of functional activity and bilateral temporal (auditory areas) and orbitofrontal hypermetabolism related to compensatory neuronal plasticity.

Idiopathic myocardial calcification: Insights from multimodality imaging

Article history: Received 3 June 2016 Accepted 9 July 2016 Available online 11 July 2016 T1 and T2 mapping in mass revealed low T1 (370 ms vs 1050 ms in the remote LV lateral myocardium) and T2 values (43 ms vs 50 ms in the remote LV lateral myocardium) (Fig. 1C, D, E). Contrast technique showed no late gadolinium enhancement (LGE) in themass itself except at its periphery (Fig. 1F). Therewas apical trans-mural LGE, but no LGE of ischemic or non-ischemic distribution in the over-all IVS wall (Fig. 1F).

Is Sarcoid Dactylitis Worse Than We ExPEcT

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Pathological Laughing: Brain SPECT Findings.

We present the case of a 40-year-old man consulting for uncontrollable episodes of laughing related to emotional lability and not systematically linked to feelings of happiness. Seven months earlier he had presented a pontine ischemic stroke related to an occlusion of the basilar and left vertebral arteries. No epileptic activity or new MRI brain lesions were found. Brain perfusion SPECT performed showed marked hypoperfusion in the right frontal inferior and temporoinsular regions, suggesting a diaschisis phenomenon caused by pontine lesions and highlighted laughing regulation pathways. The patient was successfully treated with a serotonergic reuptake inhibitor, fluoxetine.

Management of Salmonella typhimurium sepsis with thoracic infectious aortitis using 18F-FDG PET/CT

Noninvasive imaging is crucial for diagnosing aortitis. However, increased wall thickness detected by CT is not specific because of correlation with age and vascular calcifications. Used as an in vivo biomarker, F-FDG may help reveal aortic inflammation. FFDG PET/CT likewise allows managing infectious aortitis, as shown for abdominal septic aortic localizations. Indeed, thoracic aorta is affected in only 17% of the cases. We report a case of thoracic infectious aortitis managed by F–FDG PET/CT as a complication of a Salmonella typhimurium sepsis. An 82-year old woman, with seropositive rheumatoid arthritis, was referred because of abdominal pain. Clinical examination revealed abdominal tenderness in the left flank. Urine analysis was related with S. typhimurium infection. Diagnosis of acute left nephritis was made. Ofloxacin was introduced but fever appeared and CRP level increased. Blood cultures grew S. typhimurium. Thoracic and abdominal CT showed aortic calcifications with no aneurysm. MRI and echocardiography, respectively, ruled out spondylodiscitis and endocarditis. Ofloxacin was replaced by ceftriaxone and gentamycin. The patient remained febrile and CRP was still elevated. Due to a suspicion of abdominal infectious aortitis, F-FDG PET/CT was performed, showing focal FDG uptake in pulmonary bi-apical nodulations (Figure 1B) and in the sternum (Figure 1C), thus revealing septic emboli. Moreover, metabolic aortic activity was focally increased in descending thoracic aorta wall thickening, then consistent with an infectious aortitis (Figure 1A). After 6-week ceftriaxone treatment, CRP decreased; F-FDG PET/CT performed three months later showed a metabolic regression of infectious lesions (Figure 2A–C); and follow up was uneventful. Associated to septic emboli, the pattern of F-FDG accumulation pointed the infectious origin of the increased thoracic aortic wall thickness. Metabolic evolution after antibiotic treatment achieved to enhance imaging specificity, regarding this patient with seropositive rheumatoid arthritis, thus candidate for a noninfectious aortitis.

Sequential FDG PET and MRI findings in a case of SMART syndrome

a Service de Biophysique et Médecine Nucléaire, Hôpitaux Universitaires de Strasbourg, France b ICube, Université de Strasbourg/CNRS (UMR 7357), Strasbourg, France c Fédération de Médecine Translationnelle de Strasbourg (FMTS), Faculté de Médecine, Strasbourg, France d Service de Neurologie, Hôpitaux Universitaires de Strasbourg, France e Service de Radiologie, Hôpitaux Universitaires de Strasbourg, France