A novel stereotactic frame for real PET-guided biopsies: A preclinical proof-of-concept.

PURPOSE: To design, build and test a stereotactic device that allows PET image-guided biopsies to be performed. METHODS: An initial prototype consisting of four main pieces, one of which contains radioactive markers to make it visible in the PET images, was built using a 3D printer. Once the device is mounted, a spherical coordinate system is built with the entrance needle point in the skin as the origin of coordinates. Two in-house software programs, namely getCoord.ijm, which obtains the spherical coordinates of the tumour tissue to be biopsied, and getNeedle.ijm, which virtualizes the inner needle tip once the puncture has taken place, were written. This prototype was tested on an FDG-doped phantom to characterize both the accuracy of the system and the procedure time. RESULTS: Up to 11 complete biopsy procedures were conducted. The mean total procedure time was less than 20min, which is less than the procedure time of conventional standard CT-guided biopsies. The overall accuracy of the system was found to be 5.0±1.3mm, which outperforms the criterion used in routine clinical practice when targeting tumours with a diameter of 10mm. CONCLUSIONS: A stereotactic frame to conduct real PET image-guided biopsies has been designed and built. A proof-of-concept was performed to characterize the system. The procedure time and accuracy of the system were found to meet the current needs of physicians performing biopsies.

Identification of low variability textural features for heterogeneity quantification of 18F-FDG PET/CT imaging / Identificación de texturas de baja variabilidad para la cuantificación de la heterogeneidad en imagen 18F-FDG PET/TC

Objective. To identify those textural features that are insensitive to both technical and biological factors in order to standardise heterogeneity studies on 18F-FDG PET imaging. Materials and methods. Two different studies were performed. First, nineteen series from a cylindrical phantom filled with different 18F-FDG activity concentration were acquired and reconstructed using three different protocols. Seventy-two texture features were calculated inside a circular region of interest. The variability of each feature was obtained. Second, the data for 15 patients showing non-pathological liver were acquired. Anatomical and physiological features such as patient's weight, height, body mass index, metabolic active volume, blood glucose level, SUV and SUV standard deviation were also recorded. A liver covering region of interest was delineated and low variability textural features calculated in each patient. Finally, a multivariate Spearman's correlation analysis between biological factors and texture features was performed. Results. Only eight texture features analysed show small variability (<5%) with activity concentration and reconstruction protocol making them suitable for heterogeneity quantification. On the other hand, there is a high statistically significant correlation between MAV and entropy (P<0.05). Entropy feature is, indeed, correlated (P<0.05) with all patient parameters, except body mass index. Conclusions. The textural features that are correlated with neither technical nor biological factors are run percentage, short-zone emphasis and intensity, making them suitable for quantifying functional changes or classifying patients. Other textural features are correlated with technical and biological factors and are, therefore, a source of errors if used for this purpose (AU)

Objetivo. Identificar las texturas que son independientes de los factores técnicos y biológicos en imagen PET con 18F-FDG con el fin de estandarizar la heterogeneidad en imagen PET. Material y métodos. Se realizaron 2 estudios. En primer lugar, se estudió la variabilidad de 72 parámetros texturales en una región de interés circular en el interior de un maniquí cilíndrico, con 19 concentraciones de actividad y 3 protocolos de reconstrucción diferentes. A continuación, se estudió una población de 15 pacientes sin captaciones hepáticas. De cada paciente se registraron el peso, altura, índice de masa corporal, volumen metabólico activo, niveles de glucosa en sangre, SUV y desviación estándar de SUV. Se obtuvieron las texturas de baja variabilidad de una región de interés centrada en hígado. Finalmente, se realizó un análisis de correlación multivariado de Spearman entre los factores biológicos y los parámetros texturales. Resultados. Solo 8 parámetros texturales muestran baja variabilidad (<5%) con la concentración de actividad y el protocolo de reconstrucción, haciéndolos adecuados para cuantificar la heterogeneidad de la región captante. Por otro lado, existe una correlación estadísticamente significativa entre el volumen metabólico activo y la entropía (p<0,05). La entropía está, además, correlacionada con los demás parámetros, excepto el índice de masa corporal. Conclusiones. Las únicas texturas que no están correlacionadas con ninguno de los parámetros anatómicos o fisiológicos son run percentage, short-zone emphasis e intensidad, siendo estas las más adecuadas para realizar análisis cuantitativos de heterogeneidades mediante parámetros de textura. Otras texturas están relacionadas con factores técnicos y biológicos y, por tanto, constituyen una fuente de errores cuando se utilizan para este fin (AU)

Identification of low variability textural features for heterogeneity quantification of 18F-FDG PET/CT imaging.

OBJECTIVE: To identify those textural features that are insensitive to both technical and biological factors in order to standardise heterogeneity studies on 18F-FDG PET imaging. MATERIALS AND METHODS: Two different studies were performed. First, nineteen series from a cylindrical phantom filled with different 18F-FDG activity concentration were acquired and reconstructed using three different protocols. Seventy-two texture features were calculated inside a circular region of interest. The variability of each feature was obtained. Second, the data for 15 patients showing non-pathological liver were acquired. Anatomical and physiological features such as patient's weight, height, body mass index, metabolic active volume, blood glucose level, SUV and SUV standard deviation were also recorded. A liver covering region of interest was delineated and low variability textural features calculated in each patient. Finally, a multivariate Spearman's correlation analysis between biological factors and texture features was performed. RESULTS: Only eight texture features analysed show small variability (<5%) with activity concentration and reconstruction protocol making them suitable for heterogeneity quantification. On the other hand, there is a high statistically significant correlation between MAV and entropy (P<0.05). Entropy feature is, indeed, correlated (P<0.05) with all patient parameters, except body mass index. CONCLUSIONS: The textural features that are correlated with neither technical nor biological factors are run percentage, short-zone emphasis and intensity, making them suitable for quantifying functional changes or classifying patients. Other textural features are correlated with technical and biological factors and are, therefore, a source of errors if used for this purpose.

ESH-ESC guidelines for the management of hypertension.

The following is a brief statement of the 2003 European Society of Hypertension (ESH)-European Society of Cardiology (ESC) guidelines for the management of arterial hypertension. The continuous relationship between the level of blood pressure and cardiovascular risk makes the definition of hypertension arbitrary. Since risk factors cluster in hypertensive individuals, risk stratification should be made and decision about the management should not be based on blood pressure alone, but also according to the presence or absence of other risk factors, target organ damage, diabetes, and cardiovascular or renal damage, as well as on other aspects of the patient's personal, medical and social situation. Blood pressure values measured in the doctor's office or the clinic should commonly be used as reference. Ambulatory blood pressure monitoring may have clinical value, when considerable variability of office blood pressure is found over the same or different visits, high office blood pressure is measured in subjects otherwise at low global cardiovascular risk, there is marked discrepancy between blood pressure values measured in the office and at home, resistance to drug treatment is suspected, or research is involved. Secondary hypertension should always be investigated. The primary goal of treatment of patient with high blood pressure is to achieve the maximum reduction in long-term total risk of cardiovascular morbidity and mortality. This requires treatment of all the reversible factors identified, including smoking, dislipidemia, or diabetes, and the appropriate management of associated clinical conditions, as well as treatment of the raised blood pressure per se. On the basis of current evidence from trials, it can be recommended that blood pressure, both systolic and diastolic, be intensively lowered at least below 140/90 mmHg and to definitely lower values, if tolerated, in all hypertensive patients, and below 130/80 mmHg in diabetics. Lifestyle measures should be instituted whenever appropriate in all patients, including subjects with high normal blood pressure and patients who require drug treatment. The purpose is to lower blood pressure and to control other risk factors and clinical conditions present. In most, if not all, hypertensive patients, therapy should be started gradually, and target blood pressure achieved progressively through several weeks. To reach target blood pressure, it is likely that a large proportion of patients will require combination therapy with more than one agent. The main benefits of antihypertensive therapy are due to lowering of blood pressure per se. There is also evidence that specific drug classes may differ in some effect or in special groups of patients. The choice of drugs will be influenced by many factors, including previous experience of the patient with antihypertensive agents, cost of drugs, risk profile, presence or absence of target organ damage, clinical cardiovascular or renal disease or diabetes, patient's preference.

Aldosterone and its blockade: a cardiovascular and renal perspective.

Aldosterone not only contributes to salt and water homeostasis, but also exerts direct cardiovascular and renal effects. Numerous experimental and clinical studies indicate that aldosterone participate in cardiac alterations associated with hypertension, heart failure, diabetes and other pathological entities. It is important to mention that dietary salt is a key factor in aldosterone-mediated cardiovascular damage, since damage was more evident in animals on a high-salt diet than animals on a low salt diet. A pathophysiological action of aldosterone involves development of extracellular matrix and fibrosis, inflammation, stimulation of reactive oxygen species production, endothelial dysfunction, cell growth and proliferation. Many studies showed local extra-adrenal production of aldosterone in brain blood vessel, and the heart, which contribute in an important manner to the pathological actions of this mineralocorticoid. Several studies such as RALES, EPHESUS, 4E and others, recently showed that mineralocorticoid-receptor (MR) antagonists, alone or in combination with ACE inhibitors or ARBs, reduced the risk of progressive target organ damage and hospitalization in patients with hypertension and heart failure. These clinical benefits support the therapeutic usefulness of MR antagonists.

Guía Europea de Prevención Cardiovascular en la Práctica Clínica (y II) / Spanish adaptation of the European Guidelines on Cardiovascular Prevention (and II)

No disponible

Calcium channel blockade and preservation of renal graft function in cyclosporine-treated recipients: a prospective randomized placebo-controlled 2-year study.

BACKGROUND: Studies have provided conflicting results as to the protective role of calcium channel blockers (CCB) in cyclosporine-treated patients with regard to blood pressure control and preservation of renal graft function. Lacidipine is a dihydropyridine CCB that possesses antioxidative, anti-atherosclerotic, and anti-adhesion properties and was shown to prevent cyclosporine-induced nephrotoxicity in a rat model. METHODS: We conducted a multicenter prospective, randomized, placebo-controlled study in 131 de novo recipients of a cadaveric renal allograft on cyclosporine therapy. The aim of this 2-year study was to assess the effects of lacidipine on graft function (plasma iohexol clearance), renal plasma flow, anastomotic arterial blood flow, deterioration of renal function, blood pressure, acute rejection, and hospitalization rate. RESULTS: A total of 118 recipients were available for intention-to-treat analysis on efficacy (lacidipine: n=59; placebo: n=59). Graft function assessed by serum creatinine concentration and glomerular filtration rate measured as plasma iohexol clearance, was persistently better in lacidipine-treated patients from 1 year onwards (respectively, P<0.01 and P<0.05). Renal plasma flow and anastomotic blood flow were not significantly higher in lacidipine-treated patients. Three patients on lacidipine therapy and four on placebo experienced treatment failure defined as an increase in serum creatinine from baseline of more than 60% (log-rank test: P=0.57). Study groups did not differ in acute rejection rate, trough blood cyclosporine concentrations, blood pressure, number of antihypertensive drugs, hospitalization rate, and adverse event rate. CONCLUSIONS: The use of calcium channel blockers in cyclosporine-treated renal recipients results in a significantly better allograft function at 2 years and this effect is independent of blood pressure lowering.

Microalbuminuria.

The capacity of microalbuminuria to predict an increased cardiovascular and renal risk is well established in diabetic patients, as well as in essential hypertensive patients and in general population. Detection of microalbuminuria could then be relevant to select specific therapeutic strategies for reducing or preventing cardiovascular events in patients with essential hypertension. Microalbuminuria is detectable in almost 40% of the population with established hypertension, particularly in those patients not controlled satisfactorily with medical therapy. Albuminuria may represent a marker of renal damage and cardiovascular risk in essential hypertension. Microalbuminuria seems to represent a simple and reproducible method to better define cardiovascular risk profile in the hypertensive patient and to stratify the prognosis in relation to renal and cardiovascular risk. ACE-inhibitors and more recently angiotensin II receptor antagonists seem to exhibit a more market capacity to reduce microalbuminuria in patients with essential hypertension or diabetes mellitus. Determination of this parameter in daily clinical practice could facilitate the stratification of risk as well as the choice of therapy in essential hypertensive patients.

Results of kidney transplantation in recipients over 70 years of age: experience at a single center.

We performed 41 kidney transplants in patients >70 years (35 single and 6 dual), with a mean recipient age of 72+/-2 years, from January 1990 to December 2001. Mean age of the donors was 69+/-12 years. Immunosuppression used triple therapy with steroids, mycophenolate mofetil, and cyclosporine or tacrolimus. Cold ischemia time was 23+/-3 hours. The incidence of primary nonfunction was 4.8%, and delayed graft function 58.5%. Acute rejection incidence was 12%. The actuarial patient survival rates at 12, 24, and 36 months were 82.5%, 82.5%, and 75%, respectively. Actuarial survival rates of the grafts censuring for death of the recipient with a functioning graft were 89.5%, 86%, and 68%, respectively. Nine of the 18 graft losses were due to recipient death. Overall, renal transplant recipients >70 years showed good results. The principal cause of graft loss was recipient death.

Hipertensión arterial después del trasplante renal / Arterial hypertension after renal transplantation

La hipertensión arterial (HTA) es extremadamente frecuente después del trasplante renal y presenta una clara relación con la nefropatía crónica del injerto y la morbimortalidad cardiovascular, ambas circunstancias principales responsables de la pérdida de los injertos renales a partir del primer año postrasplante.En su etiopatogenia participan numerosos factores, dentro de los cuales la propia medicación inmunosupresora, en concreto, los inhibidores de la calcineurina, desempeñan un papel fundamental. La HTA postrasplante ha de ser tratada enérgicamente con medidas higiénico-dietéticas y farmacológicas. La elección del fármaco antihipertensivo ha de realizarse de manera individualizada. Probablemente los calcioantagonistas sean los fármacos de primera línea, salvo en aquellos pacientes con proteinuria, en los que sería preferible utilizar un inhibidor de la enzima convertidora de angiotensina o un antagonista de los receptores de angiotensina II. El advenimiento de nuevos fármacos inmunosupresores sin capacidad nefrotóxica ni prohipertensiva facilitará en un futuro el desarrollo de nuevos protocolos de inmunosupresión que permitirán minimizar la nefrotoxicidad, con el consiguiente impacto en la HTA postrasplante (AU)

What is the optimal blood pressure target in renal patients?

Chronic renal failure and arterial hypertension run in parallel. New goal BP levels have been established as 130/85 mm Hg and 125/75 mm Hg, depending on whether the level of proteinuria is less than or greater than 1 g/d. New and lower threshold BP (> 130/85 mm Hg) to initiate pharmacologic therapy is required in the presence of renal failure, to facilitate the strict BP control that is required. Hence, it is necessary to consider that both renal and cardiovascular protection are obtained with strict BP control, which otherwise seems to require blockade of angiotensin II effects when proteinuria above 1 g/d is present.