Establishment of diagnostic reference levels in cardiac CT in France: a need for patient dose optimisation.

The objective of this study was to propose diagnostic reference levels (DRLs) for coronary computed tomography angiography (CCTA), in the context of a large variability in patient radiation dose, and the lack of European recommendations. Volume Computed Tomography Dose Index (CTDIvol) and dose-length product (DLP) were collected from 460 CCTAs performed over a 3-month period at eight French hospitals. CCTAs (∼50 per centre) were performed using the routine protocols of the centres, and 64- to 320-detector CT scanners. ECG gating was prospective (n = 199) or retrospective (n = 261). The large gap in dose between these two modes required to propose specific DRLs: 26 and 44 mGy for CTDIvol, and 370 and 970 mGy cm for DLP, respectively. This study confirms the large variability in patient doses during CCTA and underlines the need for the optimisation of cardiac acquisition protocols. Availability of national DRLs should be mandatory in this setting.

[Contribution of 64-slice cardiac tomodensitometry for non-invasive diagnosis of acute myocarditis]. / Apport de la tomodensitométrie cardiaque-64 coupes au diagnostic non invasif de la myocardite aiguë

BACKGROUND: The association of acute chest pain, elevation of the cardiac enzymes and biological markers of inflammation suggests the diagnosis of myocarditis. The aim of the present study is to evaluate the diagnostic value of the multidetectors cardiac tomodensitometry (MDCT) for the confirmation of this diagnosis. PATIENTS AND METHODS: From October 2005 to April 2011, 39 patients aged 15.4 to 75.7years (mean 43.3±15.1) underwent a MDCT for suspected acute myocarditis (chest pain, elevation of troponin I, systemic inflammation). The electrocardiogram highlighted repolarization disorders in 27 (69%) patients (negative T waves, elevation of ST segment). The MDCT consisted in a first acquisition phase (imaging of coronary arteries) followed 7minutes later by a late acquisition, with thicker slices (imaging of the myocardium). When the MDCT was performed after a coronary angiography, only the late acquisition was performed. Sixteen patients then underwent a cardiac MRI. RESULTS: No significant coronary stenoses were found in all patients. The MDCT showed homogeneous myocardial enhancement on the early acquisition. A subepicardial late enhancement was found in 30 (76.9%) patients. The subepicardial enhancement was mainly found in the lateral myocardium. In patients who underwent cardiac MRI and MDCT (n=16), there was a good correlation between the enhanced segments. MDCT found differential diagnosis in 11 patients (myocardial infarction, Tako-Tsubo). CONCLUSION: The ECG-gated MDCT is a non-invasive and reliable diagnostic tool in patient with suspected myocarditis. It allows at the same time to rule out a significant coronary disease, when no coronary angiography was performed, and to show subepicardial enhancement confirming the diagnosis of myocarditis. While cardiac MRI remains the gold standard, MDCT could prove useful when there is no access to or contraindication for an MRI, studying both the coronary arteries and the myocardium.

[Use of 64-slice tomodensitometry after cardiac arrest]. / Une indication de scanner 64-coupes en urgence après arrêt cardiaque réanimé

Acute coronary occlusion is the leading cause of out-of-hospital cardiac arrest, so patients are usually referred for immediate coronary angiography and angioplasty. We report here the observation of such a patient who previously underwent a coronary artery bypass intervention and who had a difficult arterial access. Moreover, the nature of the grafts was unknown (saphenous and/or mammary arteries). Multi-slice cardiac tomo-densitometry was performed rather than a conventional coronary angiography and it allowed the analysis of native arteries and grafts. There was no stenosis and angioplasty was unnecessary.

[Subcutaneous trochanteric bursitis: an unrecognized cause of peritrochanteric pain revealed by imaging]. / La bursite sous-cutanée trochantérique. Cause méconnue de douleur péritrochantérienne révélée par l'imagerie.

We present four cases of subcutanea trochanterica bursitis (one involving both sides). The bursitis was acute and inflammatory in two cases, chronic and microtraumatic in one, asymptomatic in one and septic in the last case. The acutely inflamed bursa may contain a blood effusion increasing the pain. CT and MRI provide distinctive images for the diagnosis of these particular types of periarticular diseases.