Implantación de un protocolo de angio-TC coronaria basado en el índice de masa corporal: reducción de dosis, calidad de imagen y rendimiento diagnóstico / Implementing a coronary CT angiography protocol based on the body mass index: radiation dose reduction, image quality, and diagnostic performance

Objetivos: Valorar la relación entre el score de calcio coronario y la elección posterior del kilovoltaje según el criterio del radiólogo en un protocolo estándar (PE) de angio-TC coronaria (aTCC) para descartar enfermedad coronaria. Cuantificar la reducción de la radiación ionizante después de vincular el kilovoltaje al índice de masa corporal en un protocolo de baja dosis (PBD) con reconstrucción iterativa de modelado. Valorar la calidad de imagen y el rendimiento diagnóstico del PBD. Material y método: Las características antropométricas, el score de calcio, los niveles de kilovoltaje y los valores de dosis estimada específica para el tamaño (SSDE) y del producto dosis-longitud fueron comparados entre un grupo de 50 pacientes con PBD reclutados prospectivamente y una cohorte histórica adquirida con el PE. Estos parámetros, el número de segmentos coronarios no valorables sin y con tolerancia de fase, la atenuación y la relación señal-ruido en la aorta ascendente en el PBD fueron correlacionados con una calidad de imagen de nivel excelente según una escala semicuantitativa. El rendimiento diagnóstico por paciente fue calculado usando la revaloración clínica a los 24 meses como el método diagnóstico de referencia, incluyendo las pruebas derivadas. Resultados: En el PE existía una relación entre la presencia de calcio coronario y la elección de kilovoltajes altos (p=0,02), que desaparecía en el PBD (p=0,47). Los valores de SSDE y de DLP en el PBD fueron significativamente inferiores y presentaron menor dispersión que en el PE (9,22 mGy [RIQ 7,84-12,1 mGy] y 97 mGy*cm [RIQ 78-134 mGy*cm] contra 26,5 mGy [RIQ 21,3-36,3 mGy] y 253 mGy*cm [RIQ 216-404 mGy*cm]; p <0,001 para las comparaciones de las medianas y de las dispersiones entre ambos grupos)...(AU)

Objectives: To evaluate the relation between the coronary calcium score and the posterior choice of kilovoltage according to radiologists’ criteria in a standard coronary CT angiography protocol to rule out coronary disease. To quantify the reduction in ionizing radiation after linking kilovoltage to patients’ body mass index in a low-dose protocol with iterative model reconstruction. To evaluate the image quality and diagnostic performance of the low-dose protocol. Material and methods: We compared anthropometric characteristics, calcium score, kilovoltage levels, size-specific dose estimates (SSDE), and the dose-length product (DLP) between a group of 50 patients who were prospectively recruited to undergo coronary CT angiography with a low-dose protocol and a historical group of 50 patients who underwent coronary CT angiography with the standard protocol. We correlated these parameters, the number of coronary segments that could not be evaluated with and without temporal padding, the attenuation, and the signal-to-noise ratio in the ascending aorta in the low-dose protocol with excellent imaging quality according to a semiquantitative scale. To calculate the diagnostic performance per patient, we used 24-month clinical follow-up including all tests as the gold standard. Results: In the standard protocol, the presence of coronary calcium correlated with the selection of high kilovoltage (P=0.02); this correlation was not found in the low-dose protocol (P=0.47). Median values of SSDE and DLP were significantly (P<0.001) lower and less dispersed in the low-dose protocol [9.22 mGy (IQR 7.84-12.1 mGy) vs. 26.5 mGy (IQR 21.3-36.3 mGy) in the standard protocol] and [97mGy*cm (IQR 78-134mGy*cm) vs. 253mGy*cm (IQR 216-404mGy*cm) in the standard protocol], respectively...(AU)

Implementing a coronary CT angiography protocol based on the body mass index: Radiation dose reduction, image quality, and diagnostic performance.

OBJECTIVES: To evaluate the relation between the coronary calcium score and the posterior choice of kilovoltage according to radiologists' criteria in a standard coronary CT angiography protocol to rule out coronary disease. To quantify the reduction in ionizing radiation after linking kilovoltage to patients' body mass index in a low-dose protocol with iterative model reconstruction. To evaluate the image quality and diagnostic performance of the low-dose protocol. MATERIAL AND METHODS: We compared anthropometric characteristics, calcium score, kilovoltage levels, size-specific dose estimates (SSDE), and the dose-length product (DLP) between a group of 50 patients who were prospectively recruited to undergo coronary CT angiography with a low-dose protocol and a historical group of 50 patients who underwent coronary CT angiography with the standard protocol. We correlated these parameters, the number of coronary segments that could not be evaluated with and without temporal padding, the attenuation, and the signal-to-noise ratio in the ascending aorta in the low-dose protocol with excellent imaging quality according to a semiquantitative scale. To calculate the diagnostic performance per patient, we used 24-month clinical follow-up including all tests as the gold standard. RESULTS: In the standard protocol, the presence of coronary calcium correlated with the selection of high kilovoltage (p = 0.02); this correlation was not found in the low-dose protocol (p = 0.47). Median values of SSDE and DLP were significantly (p < 0.001) lower and less dispersed in the low-dose protocol [9.22 mGy (IQR 7.84-12.1 mGy) vs. 26.5 mGy (IQR 21.3-36.3 mGy) in the standard protocol] and [97 mGy cm (IQR 78-134 mGy cm) vs. 253 mGy cm (IQR 216-404 mGy cm) in the standard protocol], respectively. The overall quality of the images obtained with the low-dose protocol was considered good or excellent in 96% of the studies. The parameters associated with image quality in a multivariable model (C statistic = 0.792) were heart rate (estimated coefficient, -0,12 [95% confidence interval: -0.2, -0.04]; p < 0.01) and the SSDE (estimated coefficient, -0,26 [95% confidence interval: -0.51, -0.01]; p < 0.05). The CAD-RADS modifier for a not fully evaluable or diagnostic study was used on two occasions (4%); the final measures for the diagnosis of coronary disease were sensitivity 100%, specificity 94%, and efficacy 94%. CONCLUSIONS: In the standard protocol, the radiologist selects higher kilovoltage for CT angiography studies for patients whose previous calcium score indicates the presence of coronary calcium. In the low-dose protocol, linking kilovoltage with body mass index enables the dose of radiation to be reduced by 65% while obtaining excellent or good image quality in 96% of studies and excellent diagnostic performance.

Subclinical cardiovascular disease and Systemic Sclerosis: A comparison between risk charts, quantification of coronary calcium and carotid ultrasonography.

BACKGROUND AND OBJECTIVES: Recently published population-based cohort studies have shown a high prevalence of cardiovascular disease in Systemic Sclerosis (SSc) patients. The aim of this study is to compare three different methods to measure cardiovascular risk in patients with scleroderma. METHODS: Forty-three SSc patients were included. A prospective study was performed for evaluation of cardiovascular risk and subclinical atheromatosis using 3 non-invasive methods: cardiovascular risk tables, carotid Doppler ultrasonography and quantification of coronary calcium by computerized tomography (CT). RESULTS: The cardiovascular risk charts for the Spanish population did not identify patients at high cardiovascular risk. Framingham-REGICOR identified 13 intermediate-risk patients. Twenty-two patients (51.2%) had plaques on carotid ultrasonography. We performed a ROC curve to identify the best cutoff point for the quantification of coronary artery calcium (CACscore), the value of CACscore > 28 AU (Agatston Units) had the highest sensitivity (73%) and specificity (81%) for the diagnosis of subclinical atheromatosis. In the multiple regression study, age and decreased HDL cholesterol levels were identified as independent factors for subclinical atherosclerotic disease. No disease-related factors were associated with increased subclinical arteriosclerosis. CONCLUSION: Carotid ultrasound and CACscore are useful for identifying subclinical atheromatosis in patients with SSc and are superior compared to risk charts used for general population. HDL cholesterol and age were independent factors for the presence of subclinical atherosclerotic disease. A carotid ultrasound or CT should be performed for early detection of subclinical atheromatosis if these factors are present.

Cardiac 18F-FDG PET/CT procedure for the diagnosis of prosthetic endocarditis and intracardiac devices. / Metodología de la PET/TC con 18F-FDG cardíaca para el diagnóstico de la endocarditis protésica y de dispositivos intracardíacos.

Infective endocarditis (IE) is a serious condition with a poor prognosis, its mortality unchanged significantly despite diagnostic and therapeutic advances in the last 30years. The diagnostic ability of the modified Duke criteria in prosthetic endocarditis and/or devices does not exceed 50%, so new tools are necessary for the diagnosis of this entity in this context. The 18F-FDG PET/CTA combines a highly sensitive technique to detect inflammatory-infectious activity with a technique with high anatomical resolution to assess the structural lesions associated with endocarditis. With a diagnostic sensitivity between 91-97%, this hybrid technique has become a useful diagnostic tool for patients with prosthetic valves or devices and suspicion of IE, becoming a major criterion in the diagnostic algorithm of current guidelines. This excellent diagnostic ability depends directly on the quality of the obtained exploration and the knowledge at the time of interpreting the images. The aim of this review is to describe and standardize the methodology of cardiac 18F-FDG PET/CTA in the diagnosis of endocarditis in prosthetic valves and intracardiac devices, with special emphasis on the particularities of the patient's preparation, the PET and CT acquisition procedures, and the subsequent imaging postprocessing and interpretation.

18F-FDG-PET/CT Angiography for the Diagnosis of Infective Endocarditis.

PURPOSE OF REVIEW: This article reviews the current imaging role of 18F-fluordeoxyglucose positron emission computed tomography (18F-FDG-PET/CT) combined with cardiac CT angiography (CTA) in infective endocarditis and discusses the strengths and limitations of this technique. RECENT FINDINGS: The diagnosis of infective endocarditis affecting prosthetic valves and intracardiac devices is challenging because echocardiography and, therefore, the modified Duke criteria have well-recognized limitations in this clinical scenario. The high sensitivity of 18F-FDG-PET/CT for the detection of infection associated with the accurate definition of structural damage by gated cardiac CTA in a combined technique (PET/CTA) has provided a significant increase in diagnostic sensitivity for the detection of IE. PET/CTA has proven to be a useful diagnostic tool in patients with suspected infective endocarditis. The additional information provided by this technique improves diagnostic performance in prosthetic valve endocarditis when it is used in combination with the Duke criteria. The findings obtained in PET/CTA studies have been included as a major criterion in the recently updated diagnostic algorithm in infective endocarditis guidelines.

[SPECT, coronary angio-CT, invasive coronary angiography and fusion images in stable coronary disease]. / SPECT, angio-TC coronaria, coronariografía invasiva e imágenes de fusión en la cardiopatía isquémica estable.

OBJECTIVES: To evaluate the usefulness of the information obtained with SPECT, coronary angio-CT and fusion images, in patients with stable ischemic disease who need invasive coronary angiography (IA). MATERIAL AND METHODS: Forty-six patients (65.98±8.3 years) with coronary disease were prospectively included. The fusion images generated after undergoing IA were used to evaluate the performance of these techniques in the diagnosis of multi-vessel coronary disease, the detection of the culprit vessel and the therapeutic management of these patients. RESULTS: In the IA, 29 of the 46 patients (63%) had multi-vessel disease. SPECT could detect it in 48.2% and coronary angio-CT could detect it in 89.6%. Concordance between coronary angio-CT and IA in the diagnosis of the culprit vessel was 77% (kappa 0.6), and between SPECT and IA it was 73% (kappa 0.56). Although fusion images could have been obtained prior to IA, they would not have changed the therapeutic approach derived from SPECT and IA. CONCLUSIONS: Coronary angio-CT has a high ability for the diagnosis of multi-vessel disease and the culprit lesion, and SPECT is a good functional complement of the IA in the detection of the most ischemic territory. However, the performance of fusion images in patients with stable ischemic disease, who have undergone a SPECT as the first non-invasive study and need IA, does not seem indicated because they would not have changed the therapeutic management derived from SPECT and IA information.

[Acute stent thrombosis and reverse transient left ventricular dilatation after performing a single-photon emission computed tomography myocardial perfusion]. / Trombosis aguda de stent y dilatación transitoria ventricular izquierda inversa tras la realización de una tomografía computarizada de emisión monofotónica de esfuerzo.

A 63-year-old male patient with a history of stent implantation in the left anterior descending three months before. Due to the presentation of vegetative symptoms, he was referred for gated-SPECT myocardial perfusion. During acquisition of the resting images he presented chest pain and ST segment elevation, so that urgent cardiac catheterization was performed, showing stent thrombosis. Rest perfusion imaging showed a defect in anterior and apical perfusion, more severe and extensive than in the stress images, with striking left ventricular dilatation and a fall in the ejection fraction related to the acute ischemia phenomenon. Intense exercise is associated with a transient activation of the coagulation system and hemodynamic changes that might induce thrombosis, especially in recently implanted coronary stents that probably still have not become completely endothelialized.

[Obtaining a formula that improves maximum oxygen consumption estimation in cycle ergometer exercise tests]. / Obtención de una fórmula que mejora la estimación del consumo máximo de oxígeno en las pruebas de esfuerzo con bicicleta ergométrica.

OBJECTIVES: To evaluate if the estimation of the maximal oxygen consumption (MO2C) in METs (metabolic equivalents) by means of the table proposed in the guidelines of the Spanish Society of Cardiology is a sufficiently reliable method when applied to the bicycle exercise test. MATERIAL AND METHODS: The MO2C in METs was obtained by gas-exchange analysis on bicycle ergometer tests in 97 healthy subjects (group i). It was compared with the estimate of METs using the table in which only watts and patient's weight were included. A better-adjusted formula was validated in 289 subjects with normal exercise myocardial perfusion gated-SPECT (group ii) using the introduction of clinical and ergometric variables. RESULTS: In group i individuals a good correlation between METs estimated with the table and those obtained through gas-exchange analysis (CCI: 0.93) was observed. However, the best adjusted formula to estimate METs in group ii subjects included watts, body mass index (BMI), age and gender (METS=11.820-0.054×age-0.189×BMI+1.031×gender+0.020×watts) (women: 0, men: 1). This formula allowed the reclassification of 46.9% of group ii subjects into the category <5METs versus the estimation by table. CONCLUSIONS: Estimating the METs with the conventional table is reliable. However, the best adjustment in subjects with normal bicycle exercise SPECT was obtained when, in addition to watts and BMI, age and gender were also considered.

[Variables that influence the indication of a second myocardial perfusion gated-SPECT after a normal stress-rest gated SPECT]. / Variables que influyen en la indicación de una segunda gated-SPECT de perfusión miocárdica después una gated-SPECTde estrés-reposo normal.

OBJECTIVE: The objective of this study was to investigate predictor variables at the moment of normal stress-rest myocardial perfusion gated SPECT for indication of a second gated SPECT. MATERIAL AND METHODS: A prospective, single center cohort study was conducted. We evaluated 2326 consecutive patients (age 63.6 ± 13 years, 57.3% females) without perfusion defects and with normal left ventricular ejection fraction on a myocardial perfusion gated SPECT. Clinical and stress test variables were studied to predict indication of a second gated SPECT and presence of reversible perfusion defects in the second gated SPECT. RESULTS: During a mean follow-up of 3.6 ± 2 years a second gated SPECT was performed in 286 patients (12.3%). Independent predictor variables of a second gated SPECT were presence of three or more cardiovascular risk factors (χ(2): 5.510; HR: 1.4; p=0.019), previous acute myocardial infarction (χ(2): 3.867; HR: 1.4; p=0.049), previous coronary revascularization (χ(2): 41.081; HR: 2.5; p<0.001), and a positive stress test (χ(2): 8.713; HR: 1.5; p=0.003). Observation of perfusion defects in the 280 patients in whom a second stress-rest gated SPECT was performed was more likely in male patients (χ(2): 4.322; HR: 1.9; p=0.038) who had a first pure pharmacological gated-SPECT (χ(2): 7.182; HR: 2.6; p=0.007). CONCLUSIONS: In patients with a first normal myocardial perfusion gated SPECT, various clinical factors and variables derived from the stress test affect the indication of a second gated SPECT and the presence of ischemia in the latter.

[Analysis of the diastolic function by myocardial perfusion gated SPECT after coronary revascularization in acute myocardial infarction]. / Análisis de la función diastólica mediante gated-SPECT de perfusión miocárdica tras revascularización coronaria en el infarto agudo de miocardio.

OBJECTIVE: To evaluate the evolutive changes in diastolic function after percutaneous coronary revascularization (PCR) in acute myocardial infarction (AMI), using myocardial perfusion gated SPECT. METHODS: Thirty-two patients (mean 61.9±9.7 years, 7 women) were studied by two at rest gated SPECT: the first gated-SPECT-1 was performed with an injection of a dose of (99m)Tc-tetrofosmin prior to PCR and the second gated-SPECT-2 between the fourth and fifth weeks after AMI. Changes of peak filling rate (PFR) and the time to peak filling rate (TTPF) were assessed between both studies, and were related to the extent of salvaged myocardium (SM), end-diastolic (EDV) and end-systolic (ESV) volumes, and left ventricular ejection fraction (LVEF) changes. RESULTS: An improvement was observed in diastolic function parameters Gated-SPECT-2: PFR increased significantly (P=0.011) while the TTPF decreased without reaching statistical significance (P=0.288). In multivariate analysis, adjusted by clinical and coronary variables, improvement of PFR was significantly associated with percentage of SM (P=0.030), increase in LVEF (P=0.004) and with ESV volume reduction (P=0.005). Improvement of TTPF was only related significantly to the percentage of SM (P=0.046). PFR increased 0.01 EDV/sec. and TTPF decreased 1.14ms for each cm(2) increase of the area of SM. CONCLUSIONS: After PCR in AMI, the myocardial perfusion gated SPECT makes it possible to assess the significant improvement in diastolic function mainly related to the amount of MS.

[Spastic coronary artery. Correlation of the myocardium at risk with scintigraphy and coronary angiography]. / Arteria coronaria espástica. Correlación del miocardio en riesgo en el estudio funcional y anatómico con gammagrafía de perfusión miocárdica y coronariografía.

A 52-year old patient, with symptoms of angina in the last month, was referred to undergo a SPECT myocardial perfusion. At an early stage of the exercise test, he showed electrical changes suggestive of inferior ischemia and the scintigraphy images showed intense and extensive inferolateral hypoperfusion during the effort, with complete reversibility at rest. Cardiac catheterization showed a right coronary artery without obstructive lesions. An endothelial dysfunction test with acetylcholine provoked diffuse spasm of the artery, which retrograded completely with intravenous nitroglycerin. An acute coronary syndrome may have causes other than obstructive lesions in epicardial arteries that induce myocardium at risk. The ischemic tissue can be identified by imaging techniques that thus guides the invasive studies to recognize dysfunctional coronary arteries.

Quality assurance of clinical transfusion practice by implementation of the privilege of blood prescription and computerized prospective audit of blood requests.

Guidelines, algorithms and recommendations have been issued in the attempt to ensure appropriateness of transfusion practice, but the results are less than satisfactory, mainly due to the difficulty to turn paper procedures into actual practice. In our hospital we have tried to overcome this difficulty through the implementation of a quality assurance programme which includes giving the privilege of nonurgent blood prescription to a limited number of physicians and a computerized prospective audit of blood requests. The latter is performed through verification of the compliance of blood requests, which are designed to include a patient's laboratory and clinical data, with hospital guidelines for the proper use of blood. In the 12 months since implementation of the computerized prospective audit the transfusion service has evaluated 7884 requests. Of these, 63.4% (n = 4998) were for red blood cells, 21.1% (n = 1664) for platelets and 15.5% (n = 1222) for fresh frozen plasma. The prospective audit showed that 96.8% and 98.1% of requests for red units and platelets were appropriate, respectively. Conversely, approximately 27% of plasma requests did not comply with guidelines, mainly because the evidence of coagulopathy was missing. However, inappropriateness of plasma requests for elective general surgery decreased from 39% at the onset of the programme to 14% in the last trimester considered. Moreover, the evaluation by retrospective audit of the proportion of patients transfused with both red blood cells and plasma in the perioperative period out of those transfused with red blood cells only, as an indicator of unwanted reconstitution of whole blood, showed that this proportion decreased from 47.6% (320/672) in the 12 months before implementation of computerized audit to 37.8% (244/646) in the following 12 months (difference = -9.8%, 95% confidence interval of the difference from -4.5% to -15.1%; P < 0.005 by chi 2 test). Our initial experience, together with the present system, shows that (1) the restriction of nonurgent blood prescription to a group of clinicians more educated in transfusion medicine than average clinicians practicing in a large multispecialty hospital is feasible; (2) prospective audit is a useful tool for assuring the quality of blood requesting.

Prospective evaluation of posttransfusion hepatitis.

The incidence of posttransfusion hepatitis (PTH) was determined prospectively at our institution. An active surveillance program of transfused surgical patients was set up; alanine aminotransferase (ALT) levels were determined before transfusion and at monthly intervals for 6 months after transfusion. Patients with confirmed ALT values greater than 2.5 times the upper reference values were referred to the out-patient clinics for diagnosis. Of 4051 surgical patients who underwent transfusion between January 1986 and December 1989, 2459 (60.7%) were enrolled in the surveillance program, and 1018 (25.1%) completed the follow-up; 238 patients received autologous blood only and were used as controls. No PTH was observed in the control patients, and the incidence of the disease in patients receiving homologous blood was 10.97 percent in 1986, 6.58 percent in 1987, 5.55 percent in 1988, and 4.29 percent in 1989; the decreasing trend is significant (p = 0.018).

Quality assessment of transfusion practice in elective surgery.

A program of quality assurance (QA) was adopted to improve blood transfusion practice in elective surgery at a large urban hospital. For this purpose, a cooperative multidisciplinary group was formed, key indicators were identified, and an organization was set up. Data collected by this organization in the 1-year period needed for implementation of the program indicated that blood misuse was common practice. In fact, overrequest, overtransfusion, excessive reconstitution of whole blood (i.e., concurrent transfusion of red cells and fresh-frozen plasma), and underuse of predeposit were found in all ten surgical departments of the hospital. In a pilot study, data were collected from one surgical department during and after the implementation phase of the QA program; comparison of these data showed a postimplementation reduction of about two thirds in overtransfusion, whereas overrequest, reconstitution of whole blood, and predeposit rates remained unchanged. These results prompted continuation of the program in order to reach a definitive evaluation of its effectiveness.