RESUMEN

PURPOSE: To evaluate the clinical applicability of a prototype virtual non-contrast (VNC) reconstruction algorithm based on coronary CT angiography (cCTA) to assess calcified coronary plaques by calcium scoring (CACS). METHODS: Eighty consecutive patients suspected of coronary artery disease were retrospectively included. All patients underwent a cardiac CT using a dual-layer spectral-detector CT system. The standardized acquisition protocol included unenhanced CACS and cCTA. Datasets were acquired using 120 keV. VNC-reconstructions were calculated from the cCTA images at 2.5 mm (VNC group 1), 2.5 of 0.9 mm (group 2), and 0.9 mm (group 3) slice thickness. We compared the Agatston score and Coronary Artery Calcium Data and Reporting System (CAC-DRS) of all VNC reconstructions with the true non-contrast (TNC)-dataset as the gold standard. RESULTS: In total, 73 patients were evaluated. Fifty patients (68.5 %) had a CACS > 0 based on TNC. We found a significant difference in the Agatston score comparing all VNC-reconstructions (1: 1.35, 2: 3.7, 3: 10.4) with the TNC dataset (3.8) (p < 0.001). Correlation analysis of the datasets showed an excellent correlation of the TNC results with the different VNC-reconstructions (r = 0.904-0.974, p < 0.001) with a slope of 1.89-2.53. Mean differences and limits of agreement by Bland-Altman analysis between TNC and group 1 were 83 and -196 to 362, respectively. By using the VNC-reconstructions, in group 1 23 patients (31.5 %), in group 2 10 (13.7 %), and in group 3 23 (31.5 %) were reclassified according to CAC-DRS compared to TNC. Classification according to CAC-DRS revealed a significant difference between TNC and group 1 (p = 0.024) and no significance compared to groups 2 and 3 (p = 0.670 and 0.273). CONCLUSION: The investigated VNC reconstruction algorithm of routine cCTA allows the detection and evaluation of coronary calcium burden without the requirement for an additional acquisition of an unenhanced CT scan for CACS and, therefore, a reduction of radiation exposure.

Asunto(s)

Calcio , Tomografía Computarizada por Rayos X , Humanos , Calcio/análisis , Estudios Retrospectivos , Estudios de Factibilidad , Tomografía Computarizada por Rayos X/métodos , Angiografía Coronaria/métodos

RESUMEN

BACKGROUND: Prolonged breath holding results in hypoxemia and hypercapnia. Compensatory mechanisms help maintain adequate oxygen supply to hypoxia sensitive organs, but burden the cardiovascular system. The aim was to investigate human compensatory mechanisms and their effects on the cardiovascular system with regard to cardiac function and morphology, blood flow redistribution, serum biomarkers of the adrenergic system and myocardial injury markers following prolonged apnoea. METHODS: Seventeen elite apnoea divers performed maximal breath-hold during cardiovascular magnetic resonance imaging (CMR). Two breath-hold sessions were performed to assess (1) cardiac function, myocardial tissue properties and (2) blood flow. In between CMR sessions, a head MRI was performed for the assessment of signs of silent brain ischemia. Urine and blood samples were analysed prior to and up to 4 h after the first breath-hold. RESULTS: Mean breath-hold time was 297 ± 52 s. Left ventricular (LV) end-systolic, end-diastolic, and stroke volume increased significantly (p < 0.05). Peripheral oxygen saturation, LV ejection fraction, LV fractional shortening, and heart rate decreased significantly (p < 0.05). Blood distribution was diverted to cerebral regions with no significant changes in the descending aorta. Catecholamine levels, high-sensitivity cardiac troponin, and NT-pro-BNP levels increased significantly, but did not reach pathological levels. CONCLUSION: Compensatory effects of prolonged apnoea substantially burden the cardiovascular system. CMR tissue characterisation did not reveal acute myocardial injury, indicating that the resulting cardiovascular stress does not exceed compensatory physiological limits in healthy subjects. However, these compensatory mechanisms could overly tax those limits in subjects with pre-existing cardiac disease. For divers interested in competetive apnoea diving, a comprehensive medical exam with a special focus on the cardiovascular system may be warranted. TRIAL REGISTRATION: This prospective single-centre study was approved by the institutional ethics committee review board. It was retrospectively registered under ClinicalTrials.gov (Trial registration: NCT02280226 . Registered 29 October 2014).

Asunto(s)

Apnea/diagnóstico por imagen , Contencion de la Respiración , Sistema Cardiovascular/diagnóstico por imagen , Buceo , Imagen por Resonancia Cinemagnética , Adaptación Fisiológica , Adulto , Apnea/sangre , Apnea/fisiopatología , Biomarcadores/sangre , Sistema Cardiovascular/metabolismo , Sistema Cardiovascular/fisiopatología , Buceo/efectos adversos , Epinefrina/sangre , Femenino , Hemodinámica , Humanos , Masculino , Persona de Mediana Edad , Péptido Natriurético Encefálico/sangre , Norepinefrina/sangre , Fragmentos de Péptidos/sangre , Valor Predictivo de las Pruebas , Flujo Sanguíneo Regional , Factores de Riesgo , Factores de Tiempo , Troponina/sangre , Función Ventricular Izquierda , Adulto Joven

RESUMEN

BACKGROUND: Prolonged apnea by breath-hold (BH) divers leads to hypoxemia and compensatory mechanisms of the cardiovascular system (i.e. increase of total peripheral resistance, increase of systolic blood-pressure, left-ventricular enlargement) to maintain oxygen supply to oxygen sensitive organs such as the brain. All these changes may result in structural myocardial or subclinical brain alterations. Therefore, the aim of this study was to investigate mid-term effects of repetitive prolonged apnea using cardiac magnetic resonance imaging (CMR) and magnetic resonance imaging of the brain. MATERIALS AND METHODS: 17 elite BH divers (15 males) were investigated at baseline, from whom 9 (7 males) were investigated again at follow-up one year later. CMR included functional imaging and tissue characterization using T1- and T2-mapping as well as late gadolinium enhancement. Results were compared intra-individually and with 50 age matched controls. RESULTS: Mean BH time were 297 ±â€¯52 s (entire cohort) and 315 ±â€¯56 s (sub-cohort) at initial, and 334 ±â€¯104 s at follow-up examination. Apnea resulted in a progressive increase of the left ventricle and impaired function, whichfully resolved after cessation of apnea. At rest, no dilation of the left ventricle was notable (LV-EDV: 106.7 ±â€¯28.8 ml; LV-EDV/BSA: 52.2 ±â€¯12.7 ml/m2). Compared to controls, the apnea group showed significantly lower volumes (LV-EDV: 106.7 ±â€¯28.8 ml vs. 140.9 ±â€¯36.3 ml, p = .008; LV-EDV/BSA: 52.2 ±â€¯12.7 ml/m2 vs. 73.7 ±â€¯12.8 ml/m2). In contrast, LV-EF showed no significant differences between both groups (61.0 ±â€¯7.0% vs. 60.9 ±â€¯3.6%). T1- and T2-mapping revealed no significant differences, neither intra-individually nor in comparison with age matched controls. (T1 pre-contrast: 974.1 ±â€¯12.9 ms vs. 969.4 ±â€¯29.0 ms, p = .2; T1 post-contrast: 368.9 ±â€¯38.5 ms vs. 966.7 ±â€¯40.5 ms, p = .4; ECV: 29.2 ±â€¯1.5% vs. 29.8 ±â€¯1.6%, p = .3; T2. 52 ±â€¯2 ms vs. 52 ±â€¯3 ms; p = .4). Except for one old embolic lesion no structural changes were found in brain imaging. CONCLUSION: Although, prolonged apnea leads to impressive adaptions of the cardiovascular system (i.e. dilation of the left ventricle) and hypertension due to peripheral vasoconstriction no mid-term morphological changes could be observed in both, the myocardium and the brain. BH divers are suitable as a model to investigate acute physiological changes of prolonged apnea and hypoxemia, but not as a model for chronic alterations.

Asunto(s)

Atletas , Encéfalo/fisiopatología , Contencion de la Respiración , Buceo , Hipoxia/fisiopatología , Miocardio/patología , Adulto , Encéfalo/diagnóstico por imagen , Femenino , Fibrosis , Corazón/diagnóstico por imagen , Corazón/fisiopatología , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Estudios Prospectivos

RESUMEN

PURPOSE: To assess the diagnostic value of contrast-enhanced multi-detector computed tomography (MD-CT) for identifying patients with left atrial appendage (LAA) thrombus or circulatory stasis. MATERIALS AND METHODS: 124 patients with a history of atrial fibrillation and/or cerebral ischemia (83 men, mean age 58.6 ±â€Š12.4 years) and with a clinical indication for MD-CT of the heart and for transesophageal echocardiography (TEE) were included in the study. LAA thrombus or thrombogenic milieu was visually identified in TEE and MD-CT. In addition, MD-CT was analyzed quantitatively measuring the Hounsfield units (HU) of the left atrium (LA), the LAA and the ascending aorta (AA), and calculating the HU ratios LAA/AA (HU [LAA/AA]) und LAA/LA (HU [LAA/LA]). Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated. RESULTS: The prevalence of a thrombus or thrombogenic milieu as assessed by TEE was 21.8 %. The HU ratio was lower in patients with thrombus or thrombogenic milieu (HU [LAA/AA]: 0.590 ±â€Š0.248 vs. 0.909 ±â€Š0.141; p < 0.001 und HU [LAA/LA] 0.689 ±â€Š0.366 vs. 1.082 ±â€Š0.228; p < 0.001). For the diagnosis of thrombus or a thrombogenic milieu, visual analysis yielded a sensitivity of 81.5 %, a specificity of 96.9 %, a PPV of 87.5 % and a NPV of 95.2 %. By combining visual and quantitative analysis with one criterion being positive, the specificity decreased to 91.8 %, the sensitivity to 77.8 %, the PPV to 72.4 %, and the NPV to 94.9 %. CONCLUSION: Visual analysis of the LAA in the evaluation of thrombus or thrombogenic milieu yields a high NPV of 95.1 % and may especially be useful to rule out LAA thrombi in patients with contraindications for TEE. Additional calculation of HU ratios did not improve the diagnostic performance of MD-CT. KEY POINTS: • MD-CT can reliably exclude atrial appendage thrombi/thrombogenic milieu. • MD-CT is an alternative method in patients with contraindications to TEE. • Calculation of relative HU ratios does not improve the diagnostic value of MD-CT.

Asunto(s)

Apéndice Atrial/patología , Medios de Contraste , Ecocardiografía Transesofágica/métodos , Aumento de la Imagen , Trombosis/diagnóstico , Adulto , Anciano , Ecocardiografía/métodos , Femenino , Hemodinámica/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Persona de Mediana Edad , Tomografía Computarizada Multidetector/métodos , Estudios Prospectivos , Sensibilidad y Especificidad

RESUMEN

PURPOSE: To determine effectiveness of lymphatic interventional procedures for treatment of chylothorax. MATERIAL AND METHODS: Analysis of interventions performed from 2001 to 2014. RESULTS: In 21 patients with therapy resistant chylothorax a lymphatic radiological intervention was attempted, which could be performed in 19 cases: 17 thoracic duct embolizations (15 transabdominal, one transzervical and one retrograde transvenous procedure), 2 percutaneous destructions of lymphatic vessels, one CT-guided injection of ethanol next to a duplicated thoracic duct. Fourteen of seventeen (82.3 %) of the technically successful embolizations lead to clinical cure. This encluded three patients with prior unsuccessful surgical thoracic duct ligation. Also the injection of ethanol was clinically effective. Complications were a bile peritonitis requiring operation, and one clinical deterioration of unknown cause. CONCLUSION: Interventional lymphatic procedures allow for effective treatment in many cases of chylothorax, and should be considered early during treatment. KEY POINTS: • Thoracic duct embolization is an effective treatment method for chylothorax. • If embolization is impossible, percutaneous lymphatic destruction or injection of sclerosants/tissue adhesive next to the thoracic duct may be tried.

Asunto(s)

Quilotórax/terapia , Embolización Terapéutica/métodos , Hemostáticos/administración & dosificación , Escisión del Ganglio Linfático/métodos , Radiografía Intervencional/métodos , Cirugía Asistida por Computador/métodos , Adulto , Anciano , Quilotórax/diagnóstico por imagen , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos X/métodos , Resultado del Tratamiento

RESUMEN

PURPOSE: To investigate the feasibility of high-dose dobutamine stress (HDDS) imaging using SSFP sequences at 3 T employing patient-adaptive local RF-shimming using a dual-source RF transmission system. MATERIALS AND METHODS: 13 Patients underwent a HDDS protocol on a 3 T MRI scanner (Achieva 3.0T-TX, Philips Healthcare), equipped with a dual-source RF transmission system. SSFP cine sequences using patient-adaptive local RF-shimming (RF-S) were compared to cine images acquired without additional shimming. Image quality was evaluated on a 4-point grading scale and number of non-diagnostic segments assessed. Contrast (CN) between myocardium (SIM) and blood pool (SIB) was calculated [(SIB-SIM)/(SIB+SIM)]. RESULTS: Image quality both at rest and maximum stress was significantly improved with RF-S (ED:3.56±0.5 vs. 3.23±0.63; ES:3.4±0.5 vs. 3.1±0.7) compared to no RF-S (ED:2.9±0.72 vs. 2.15±0.78; ES:2.64±0.74 vs. 1.95±0.76; p<0.01). The amount of non-diagnostic segments was significantly reduced when using RF-S at rest and stress (3 vs. 39; 19 vs. 78, p<0.05). All HDDS studies were diagnostic if performed with RF-S (n=13/13) in comparison to conventional shimming (n=5/13). Image contrast was improved for SSFP sequences with RF-S (0.53±0.08) compared to conventional images (0.46±0.09, p=0.06). CONCLUSION: Patient-adaptive local RF-shimming using a dual-source RF transmission system allows for reliable SSFP imaging in a clinical high-dose dobutamine stress protocol at 3 T. RF-S significantly improves image quality and reduces the number of non-diagnostic myocardial segments.

Asunto(s)

Algoritmos , Oclusión Coronaria/patología , Dobutamina/administración & dosificación , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Imagen por Resonancia Cinemagnética/métodos , Prueba de Esfuerzo/métodos , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Sensibilidad y Especificidad

RESUMEN

OBJECTIVE: The purpose of this study was to evaluate the feasibility and diagnostic accuracy of a combined spoiled gradient-echo (sGRE) and tagged gradient-echo (SPAMM-GRE) protocol for detection of coronary artery disease (CAD) during high-dose dobutamine stress at 3 T. METHOD: The study protocol was approved by the local ethics committee. For stress testing, a standard high-dose dobutamine protocol was employed. Image quality at the highest stress level and diagnostic accuracy of the sGRE and SPAMM-GRE sequences were compared. The final study population consisted of 37 patients. RESULTS: The mean image quality score was 2.6±0.6 for the sGRE sequence and 2.4±0.6 for the SPAMM-GRE sequence (p>0.05). Sensitivity, specificity and diagnostic accuracy were 0.81, 0.86, 0.84 and 0.88, 0.86, 0.86 for the sGRE and SPAMM-GRE, respectively. In three cases with new wall motion abnormalities (WMAs), detected by sGRE and SPAMM-GRE, WMAs were detected at a lower stress level by tagging. CONCLUSION: The combined sGRE and SPAMM-GRE high-dose dobutamine protocol at 3 T is feasible and delivers good diagnostic accuracy. Tagging increases the sensitivity of high-dose dobutamine stress testing for detection of CAD and may allow for detection of new WMAs at lower stress levels compared with sGRE alone.

Asunto(s)

Cardiotónicos , Enfermedad Coronaria/diagnóstico , Dobutamina , Ecocardiografía de Estrés/métodos , Angiografía Coronaria/métodos , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad

Asunto(s)

Insuficiencia de la Válvula Aórtica/congénito , Válvula Aórtica/anomalías , Aortografía , Angiografía por Resonancia Magnética , Imagen por Resonancia Cinemagnética , Imagen por Resonancia Magnética , Tronco Arterial Persistente/diagnóstico , Válvula Aórtica/patología , Insuficiencia de la Válvula Aórtica/diagnóstico , Niño , Angiografía Coronaria , Anomalías de los Vasos Coronarios , Ecocardiografía , Humanos , Masculino , Complicaciones Posoperatorias/diagnóstico , Tronco Arterial Persistente/cirugía

RESUMEN

The purpose of this study was to evaluate high-resolution (HR) myocardial first-pass perfusion in healthy volunteers at 3 T compared to a typical clinical imaging protocol at 1.5 T, with respect to overall image quality and the presence of subendocardial dark rim artifacts. Myocardial first-pass rest perfusion studies were performed at both field strengths using a T1-weighted saturation-recovery segmented k-space gradient-echo sequence combined with parallel imaging (Gd-DTPA 0.05 mmol/kg). Twenty-six healthy volunteers underwent (1) a HR perfusion scan at 3 T(pixel size 3.78 mm(2)) and (2) a standard perfusion approach at 1.5 T(pixel size 9.86 mm(2)). The contrast enhancement ratio (CER) and overall image quality (4-point grading scale: 4: excellent; 1: non-diagnostic) were assessed, and a semiquantitative analysis of dark rim artifacts was performed for all studies. CER was slightly higher (1.31 +/- 0.32 vs. 1.14 +/- 0.34; p<0.01), overall image quality was significantly improved (3.03 +/- 0.43 vs. 2.37 +/- 0.39; p<0.01), and the number of dark rim artifacts (139 +/- 2.09 vs. 243 +/- 2.33; p<0.01) was significantly reduced for HR perfusion imaging at 3 T compared to the standard approach at 1.5 T. HR myocardial rest perfusion at 3 T is superior to the typical clinical perfusion protocol performed at 1.5 T with respect to the overall image quality and presence of subendocardial dark rim artifacts.

Asunto(s)

Aumento de la Imagen , Procesamiento de Imagen Asistido por Computador , Angiografía por Resonancia Magnética/métodos , Ventriculografía de Primer Paso/métodos , Adolescente , Adulto , Artefactos , Medios de Contraste/administración & dosificación , Femenino , Gadolinio DTPA , Humanos , Masculino , Valores de Referencia

RESUMEN

This study aimed to evaluate the influence of a new navigator technique (3D MAG) on navigator efficiency, total acquisition time, image quality and diagnostic accuracy. Fifty-six patients with suspected coronary artery disease underwent free breathing navigator gated coronary MRA (Intera, Philips Medical Systems, 1.5 T, spatial resolution 0.9x0.9x3 mm3) with and without 3D MAG. Evaluation of both sequences included: 1) navigator scan efficiency, 2) total acquisition time, 3) assessment of image quality and 4) detection of stenoses >50%. Average navigator efficiencies of the LCA and RCA were 43+/-12% and 42+/-12% with and 36+/-16% and 35+/-16% without 3D MAG (P<0.01). Scan time was reduced from 12 min 7 s without to 8 min 55 s with 3D MAG for the LCA and from 12 min 19 s to 9 min 7 s with 3D MAG for the RCA (P<0.01). The average scores of image quality of the coronary MRAs with and without 3D MAG were 3.5+/-0.79 and 3.46+/-0.84 (P>0.05). There was no significant difference in the sensitivity and specificity in the detection of coronary artery stenoses between coronary MRAs with and without 3D MAG (P>0.05). 3D MAG provides accelerated acquisition of navigator gated coronary MRA by about 19% while maintaining image quality and diagnostic accuracy.

Asunto(s)

Angiografía Coronaria/métodos , Enfermedad de la Arteria Coronaria/diagnóstico , Imagenología Tridimensional , Angiografía por Resonancia Magnética/métodos , Anciano , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Estudios Prospectivos , Sensibilidad y Especificidad , Factores de Tiempo