Diagnóstico prenatal del arco aórtico derecho, importancia de los planos de Yagel. Nuestra experiencia, descripción de 2 casos / Prenatal diagnosis of right aortic arch, importance of examination of the fetal heart by 5 short-axis views. Our experience, description of 2 cases

El arco aórtico derecho es una entidad rara (prevalencia del 0,1%) que se adscribe a un grupo de malformaciones poco frecuentes y escasamente descritas en la bibliografía en su forma prenatal; sin embargo, no es infrecuente hallarlas como causa de enfermedad respiratoria o digestiva (refractarias a tratamiento) en pacientes adultos, e incluso como procesos vasculares severos con morbimortalidad elevada. Sus variantes pueden condicionar sintomatología compresiva y estar relacionadas con anomalías cardíacas (hasta 90%) y/o con la microdeleción 22q11 (hasta un 46%). El corte ecográfico de 3 vasos-tráquea es fundamental para su diagnóstico prenatal, y tras su detección está indicada una evaluación exhaustiva del corazón fetal, distinguir sus variantes y/o un estudio cromosómico-genético específico. En presencia de otras anomalías el pronóstico es pobre; los casos aislados suelen tener una evolución posnatal oligo o asintomática

Right aortic arch, which belongs to a group of rare malformations, is an uncommon finding (incidence of 0.1%) and few cases of prenatal forms have been described in the literature. Nevertheless, it is not unusual to find these anomalies as the cause of respiratory or digestive disease (refractory to treatment) in adult patients and even as severe vascular processes with high morbidity and mortality. Its variants may cause compressive symptoms and be associated with heart defects (up to 90%) and/or 22q11 microdeletion (up to 46%). The 3 vessels and trachea view is essential for the prenatal diagnosis of right aortic arch. Detection of this condition must be considered an indication for foetal echocardiography, to distinguish its variants, and/or specific chromosome/genetic testing. Isolated right aortic arch is usually asymptomatic, although the outcome of right aortic arch associated with other abnormalities is poor

Negative pressure wound therapy with instillation, a cost-effective treatment for abdominal mesh exposure.

PURPOSE: Negative pressure wound therapy with instillation (NPWTi) has been proved to be a safe and effective treatment option for abdominal wall wound dehiscence with mesh exposure. Our aim in this study is to examine whether it is also cost-effective. METHODS: We performed a retrospective cohort study with 45 patients treated for postoperative abdominal wall wound dehiscence and exposed mesh: 34 were treated with conventional wound therapy (CWT) and 11 with NPWTi. We carried out a cost analysis for each treatment group using the Diagnosis-related group (DRG) system and a second evaluation using the calculated costs "per hospital stay". The differences between NPWTi and CWT were calculated with both evaluation systems. Comparative analysis was performed using the Mann-Whitney U test. RESULTS: Mean costs using the DRG estimation were 29,613.71€ for the CWT group and 15,093.37€ for the NPWTi group, and according to the calculated expenses "per hospital stay", 17,322.88€ for the CWT group and 15,284.22€ for the NPWTi group. NPWTi showed a reduction in the total expense of treatment, related to a reduction in episodes of hospitalization and number of surgeries required to achieve wound closure. However, differences were not statistically significant in our sample. CONCLUSIONS: NPWTi proves to be an efficient treatment option for abdominal wall wound dehiscence with mesh exposure, compared to CWT. More trials aimed to optimize treatment protocols will lead to an additional increase in NPWTi efficiency. In addition, to generalize our results, further studies with larger samples would be necessary.

Miopatía de depósito de nemalina y artrogriposis congénita / Nemaline myopathy and congenital arthrogryposis

La artrogriposis es un síndrome complejo, que responde etiológicamente a numerosas causas congénitas y adquiridas. Presentamos un caso familiar de artrogriposis. La necropsia aportó el hallazgo de inclusiones rojo-púrpura en el sarcoplasma del tejido muscular, sugestiva de miopatía por nemalinas

Arthrogryposis is a complex syndrome, the aetiology of which can be traced to numerous congenital and acquired causes. We present a case of familiar arthrogryposis. Necropsy revealed red-purple rod-like structures in the sarcoplasm of the muscle tissue, suggestive of nemaline myopathy

An intelligent support system for automatic detection of cerebral vascular accidents from brain CT images.

OBJECTIVE: This paper presents a Radial Basis Functions Neural Network (RBFNN) based detection system, for automatic identification of Cerebral Vascular Accidents (CVA) through analysis of Computed Tomographic (CT) images. METHODS: For the design of a neural network classifier, a Multi Objective Genetic Algorithm (MOGA) framework is used to determine the architecture of the classifier, its corresponding parameters and input features by maximizing the classification precision, while ensuring generalization. This approach considers a large number of input features, comprising first and second order pixel intensity statistics, as well as symmetry/asymmetry information with respect to the ideal mid-sagittal line. RESULTS: Values of specificity of 98% and sensitivity of 98% were obtained, at pixel level, by an ensemble of non-dominated models generated by MOGA, in a set of 150 CT slices (1,867,602pixels), marked by a NeuroRadiologist. This approach also compares favorably at a lesion level with three other published solutions, in terms of specificity (86% compared with 84%), degree of coincidence of marked lesions (89% compared with 77%) and classification accuracy rate (96% compared with 88%).

Revisión de los pacientes estudiados por coagulopatía en una unidad de Oncohematología / Review of patients studied for coagulopathy in a Hematology/Oncology unit

INTRODUCCIÓN: Los síntomas/signos indicativos de una coagulopatía son un motivo de consulta frecuente en las unidades de Hematología Pediátrica. Tanto la clínica como los antecedentes familiares son fundamentales para el diagnóstico. PACIENTES Y MÉTODOS: Estudio retrospectivo y descriptivo de los pacientes derivados a una consulta de Hematología Pediátrica de un hospital de tercer nivel por posible coagulopatía durante el año 2012. RESULTADOS: Se estudiaron 47 niños. El 61,7% no había presentado previamente sangrado. El motivo de derivación más frecuente fue un tiempo de tromboplastina parcial activada alargado sin hemorragia (42,5%); de estos, un 25% fue diagnosticado de una coagulopatía con riesgo real de sangrado. En los pacientes derivados por tiempo de tromboplastina parcial activada alargado con clínica hemorrágica se detecta una coagulopatía con riesgo real de sangrado con mayor frecuencia (41,7%). En los niños con antecedentes familiares de sangrado se diagnostica con más frecuencia una coagulopatía con riesgo real de sangrado: 37,5 vs. 14,3% (niños sin antecedentes familiares). Los diagnósticos han sido: sano (48,9%), enfermedad de von Willebrand tipo1 (19,1%), déficit de factor XII (19,1%), déficit de factor XI(4,2%), déficit de precalicreína/cininógeno de alto peso molecular (2,1%), déficit adquirido de factor X (2,1%) y déficit de factor IX (2,1%). CONCLUSIONES: Los antecedentes personales y familiares de sangrado orientan el diagnóstico de una coagulopatía. El motivo de derivación debería basarse en mayor medida en la clínica hemorrágica y no solo en un tiempo de laboratorio alterado. Los diagnósticos más frecuentes han sido enfermedad de von Willebrand tipo 1 y déficit de factor XII

INTRODUCTION: Symptoms/signs suggestive of coagulopathy is a frequent complaint in Pediatric Hematology units. Both the clinical and family history are essential for diagnosis. PATIENTS AND METHODS: Retrospective and descriptive study of patients referred to a Pediatric Hematology unit of a tertiary hospital for possible coagulopathy during 2012. RESULTS: A total of 47 children were studied, of whom 61.7% had not previously suffered bleeding. The most frequent reason for referral was an eloganted activated partial thromboplastin time without any hemorrhage (42.5%), of these, 25% were diagnosed of a coagulopathy with a real risk of bleeding. While patients referred due to an eloganted activated partial thromboplastin time with bleeding more frequently (41.7%) have a coagulopathy with a real risk of bleeding. Children with a family history of bleeding are diagnosed more frequently with a coagulopathy with a real risk of bleeding: 37.5% (family history) vs. 14.3% (without). The most frequent diagnoses were: healthy children (48.9%), von Willebrand type 1 disease (19.1%), factor XII deficiency (19.1%), factor XI deficiency (4.2%), prekalikrein/high molecular weight kininogen deficiency (2.1%), acquired deficiency of factor X (2.1%), and factor IXdeficiency (2.1%). CONCLUSIONS: A thorough personal and family bleeding history and physical examination are the first steps for a correct differential diagnosis. The reason for referral should be based more on clinical bleeding and not just on an abnormal coagulation time. The most frequent diagnoses were type 1 von Willebrand disease and factor XII deficiency

[Review of patients studied for coagulopathy in a Hematology/Oncology unit]. / Revisión de los pacientes estudiados por coagulopatía en una unidad de Oncohematología.

INTRODUCTION: Symptoms/signs suggestive of coagulopathy is a frequent complaint in Pediatric Hematology units. Both the clinical and family history are essential for diagnosis. PATIENTS AND METHODS: Retrospective and descriptive study of patients referred to a Pediatric Hematology unit of a tertiary hospital for possible coagulopathy during 2012. RESULTS: A total of 47 children were studied, of whom 61.7% had not previously suffered bleeding. The most frequent reason for referral was an eloganted activated partial thromboplastin time without any hemorrhage (42.5%), of these, 25% were diagnosed of a coagulopathy with a real risk of bleeding. While patients referred due to an eloganted activated partial thromboplastin time with bleeding more frequently (41.7%) have a coagulopathy with a real risk of bleeding. Children with a family history of bleeding are diagnosed more frequently with a coagulopathy with a real risk of bleeding: 37.5% (family history) vs. 14.3% (without). The most frequent diagnoses were: healthy children (48.9%), von Willebrand type 1 disease (19.1%), factor xii deficiency (19.1%), factor xi deficiency (4.2%), prekalikrein/high molecular weight kininogen deficiency (2.1%), acquired deficiency of factor x (2.1%), and factor ix deficiency (2.1%). CONCLUSIONS: A thorough personal and family bleeding history and physical examination are the first steps for a correct differential diagnosis. The reason for referral should be based more on clinical bleeding and not just on an abnormal coagulation time. The most frequent diagnoses were type 1 von Willebrand disease and factor xii deficiency.

Resultados de la reparación artroscópica mediante anclaje óseo sin nudo de lesiones del fibrocartílago triangular asociadas a fractura de extremidad distal de radio / Arthroscopic knotless anchor repair of triangular fibrocartilage in distal radius fracture

Introducción y objetivo. Las lesiones del fibrocartílago triangular (FCT) están asociadas en muchas ocasiones con inestabilidad de la articulación radiocubital distal. El tratamiento artroscópico de estas lesiones mejora el pronóstico funcional de los pacientes afectados. El objetivo del presente trabajo es evaluar los resultados funcionales y laborales de la reparación artroscópica con anclaje óseo sin nudo de lesiones del FCT asociadas a fracturas de extremidad distal del radio. Material y método. Estudio observacional, descriptivo entre noviembre de 2011 y enero de 2014 de 21 pacientes con fractura de radio distal asociada a lesiones tipo IB de Palmer (clases 2 y 3 de Atzei) del FCT tratados mediante reparación artroscópica con anclaje óseo sin nudo (PopLok® 2,8 mm, ConMed, EE. UU.). El tiempo medio de seguimiento fue de 18 meses. Analizamos los resultados funcionales (Mayo Wrist Score) y laborales. La edad media fue de 43,0 ± 8,8 años, con un 19% de mujeres. Se hallaron 5 casos con lesión escafolunar asociada. Resultados. La media obtenida en la escala funcional de Mayo Wrist Score fue de 83,4 ± 16,1 puntos. El tiempo de baja medio fue de 153,16 ± 48,5 días. La recuperación laboral sin limitaciones fue posible en el 89,5% de los casos. No se recogieron complicaciones postoperatorias. Conclusiones. La reparación artroscópica con anclaje óseo sin nudo de lesiones IB del FCT en pacientes con fractura de radio distal supone un método de tratamiento mínimamente invasivo, que mejora la tensión en la reparación y evita el posterior destensado, en nuestra experiencia, con baja tasa de complicaciones y buenos resultados funcionales y laborales (AU)

Introduction and objective. Lesions of triangular fibrocartilage (TFC) are associated with distal radioulnar joint instability. Arthroscopic treatment of these lesions improves functional outcome of affected patients. The aim of the present work is to evaluate functional and occupational outcome of TCF repair using an arthroscopic knotless anchor device in patients with associated distal radius fracture. Material and methods. An observational, descriptive study was carried out between November 2011 and January 2014 including 21 patients with distal radius fracture and Palmer 1 B lesions of TCF (Atzei class 2 and 3) that were treated by arthroscopic knotless anchor (PopLok® 2,8 mm, ConMed, USA). Mean follow-up was 18 months. Functional (Mayo Wrist Score) and occupational outcome results were analyzed. Mean age of the group was 43.0 ± 8.8 years, with 19% of the patients being female. There was an associated scapholunate lesion in 5 cases. Results. Functional results reached a mean of 83.4 ± 16.1 points onMayo Wrist Score. Mean sick-leave time was 153.16 ± 48.5 days. Complete occupational reintegration was reached in 89.5% of cases. There were no postoperative complications. Conclusions. Arthroscopic knotless anchor repair of 1 B TFC tears is a minimally invasive method of treatment that improves tension of fixation, avoiding subsequent loosen, in our experience, with few complications and good functional and occupational results (AU)

Arthroscopic knotless anchor repair of triangular fibrocartilage in distal radius fracture.

INTRODUCTION AND OBJECTIVE: Lesions of triangular fibrocartilage (TFC) are associated with distal radioulnar joint instability. Arthroscopic treatment of these lesions improves functional outcome of affected patients. The aim of the present work is to evaluate functional and occupational outcome of TCF repair using an arthroscopic knotless anchor device in patients with associated distal radius fracture. MATERIAL AND METHODS: An observational, descriptive study was carried out between November 2011 and January 2014 including 21 patients with distal radius fracture and Palmer 1B lesions of TCF (Atzei class 2 and 3) that were treated by arthroscopic knotless anchor (PopLok® 2,8mm, ConMed, USA). Mean follow-up was 18 months. Functional (Mayo Wrist Score) and occupational outcome results were analyzed. Mean age of the group was 43.0±8.8 years, with 19% of the patients being female. There was an associated scapholunate lesion in 5 cases. RESULTS: Functional results reached a mean of 83.4±16.1 points onMayo Wrist Score. Mean sick-leave time was 153.16±48.5 days. Complete occupational reintegration was reached in 89.5% of cases. There were no postoperative complications. CONCLUSIONS: Arthroscopic knotless anchor repair of 1B TFC tears is a minimally invasive method of treatment that improves tension of fixation, avoiding subsequent loosen, in our experience, with few complications and good functional and occupational results.

Diagnóstico y tratamiento quirúrgico del hemangiopericitoma facial. Caso clínico / Diagnosis and surgical treatment of facial hemangiopericytoma. Case report

El hemangiopericitoma es un raro tumor de origen mesenquimal del que existe poca información en cuanto a su presentación, diagnóstico, tratamiento y pronóstico. Conceptualmente, su entidad se solapa con el tumor fibroso solitario con el que comparte rasgos. Describimos el caso de un paciente de 41 años de edad con un hemangiopericitoma facial a la vez que destacamos la importancia de un diagnóstico adecuado y precoz de esta entidad para su correcto tratamiento (AU)

Hemangiopericytoma is a rare tumor of mesenchymal origin and there is little information regarding its presentation, diagnosis, treatment and prognosis. Conceptually, this entity overlaps with the solitary fibrous tumor, with shared histological features. We describe a clinical case of facial hemangiopericytoma, highlighting the importance of a correct and early diagnosis for proper treatment (AU)

Carcinoma espinocelular infiltrante de base de cráneo en paciente de 16 años con albinismo óculo-cutáneo / Squamous cell carcinoma infiltrating skull base in 16 years old patient with oculo-cutaneous albinism

Presentamos el caso de una adolescente africana de 16 años de edad afectada por albinismo óculo-cutáneo, que desarrolló un carcinoma epidermoide en pabellón auricular derecho que requirió escisión radical y reconstrucción con colgajo TRAM libre. El albinismo es un trastorno metabólico genético que consiste en la incapacidad hereditaria para sintetizar melanina. Tiene dos variantes clínicas: el albinismo ocular y el albinismo óculo-cutáneo. En determinados países africanos, los pacientes afectos por esta enfermedad son socialmente rechazados y por ello no se les presta un control sanitario adecuado. Por esta razón el tumor llevaba varios años de evolución y cuando la paciente fue vista en nuestro centro, existía una infiltración profunda con afectación severa de la base del cráneo. La compleja anatomía de las estructuras vitales en esta región hace que la resección quirúrgica de los tumores sea complicada. Comentamos las peculiaridades en la reconstrucción de casos complejos en la base lateral del cráneo con proyección a la zona temporal (AU)

We present a 16 year-old girl from Africa, affected by an oculo-cutaneous albinism, who developed a squamous cell carcinoma of the right ear that was treated by radical surgery and reconstructed with a free TRAM flap. Albinism is a genetic metabolic disease that is characterized by an impossibility to produce melanin. It presents two variations: ocular and oculo-cutaneous. In some african countries, patients affected by the disease are socially rejected and they do not receive right medical treatments. For this reason the tumor was infiltrating very deeply, affecting the cranial base when our patient was visited in our hospital. The complex anatomy of the vital structures in this area makes surgical resection of tumors involving the skull base extremely difficult. We review some concepts about the treatment of lateral and temporal skull base tumors (AU)

Innovador tratamiento de heridas abdominales complejas mediante terapia de presión negativa con instilación intermitente / Novel treatment of complex abdominal wounds with negative pressure therapy with intermittent instillation

Describimos nuestra experiencia en el tratamiento de heridas abdominales postquirúrgicas dehiscentes y contaminadas con exposición de material protésico, mediante terapia de presión negativa con instilación intermitente de soluciones tópicas. Este dispositivo nos permitió el rescate de pacientes pluripatológicos evitando una reintervención compleja de alta morbi-mortalidad y facilitando el cierre de la herida, además con conservación de la malla en la mayor parte de los casos (AU)

The present data reports our experience in the treatment of postsurgical dehiscent and infected abdominal wounds with exposure of prosthetic material with negative pressure therapy with intermittent instillation of topical solutions. This device allowed the rescue of pluripatological patients avoiding a complex resurgery of high morbi-mortality and facilitating wound closure, besides with conservation of the mesh in most of the cases (AU)

[Talocalcaneonavicular dislocation without associated fractures]. / Luxación talo-calcáneo-navicular sin fracturas asociadas.

Talocalcaneonavicular or subtalar dislocation is the simultaneous dislocation of the talar joints at the talocalcaneal and talonavicular levels. It may occur in any direction and results in foot deformity. The most common type is medial dislocation. Lateral, anterior and posterior dislocations are less common. These dislocations are associated with osteochondral fractures. Closed reduction and immobilization continue to be the cornerstones of treatment. X-rays and computerized axial tomography scan of the involved ankle and foot confirm the congruence of the subtalar joint after reduction and rule out fractures. Magnetic resonance imaging is a good alternative to assess talar vascular necrosis during the followup of these patients. The case of a medial subtalar dislocation in a 52 year-old patient is reported herein together with its diagnostic and therapeutic management and a case review from the medical literature.

Misalignments calibration in small-animal PET scanners based on rotating planar detectors and parallel-beam geometry.

Technological advances have improved the assembly process of PET detectors, resulting in quite small mechanical tolerances. However, in high-spatial-resolution systems, even submillimetric misalignments of the detectors may lead to a notable degradation of image resolution and artifacts. Therefore, the exact characterization of misalignments is critical for optimum reconstruction quality in such systems. This subject has been widely studied for CT and SPECT scanners based on cone beam geometry, but this is not the case for PET tomographs based on rotating planar detectors. The purpose of this work is to analyze misalignment effects in these systems and to propose a robust and easy-to-implement protocol for geometric characterization. The result of the proposed calibration method, which requires no more than a simple calibration phantom, can then be used to generate a correct 3D-sinogram from the acquired list mode data.

Apoptotic mechanisms are involved in the death of Strongyloides venezuelensis after triggering of nitric oxide.

Despite progress in understanding the role of nitric oxide (NO) in the pathogenesis of helminth infections, the role in strongyloidosis is unknown. Firstly, we studied the production of NO in mice infected with Strongyloides venezuelensis as well as in macrophage cultures stimulated with parasite antigens. Somatic larvae 3 (L3) and excretory-secretory female antigens stimulate specific NO production measured by Griess reaction and expression of inducible NO synthase by RT-PCR and quantitative PCR. Moreover, mice infected with S. venezuelensis produce NO in migration stages. Secondly, we analysed the effect of NO production on L3 and females of S. venezuelensis using NO donors such as diethylenetriamine and 3,3-bis(aminoethyl)-1-hydroxy-2-oxo-1-triazene. Parasites died after NO donor treatment in a dose-dependent manner. Finally, apoptotic mechanisms are involved in the death of S. venezuelensis larvae.

A method for small-animal PET/CT alignment calibration.

Small-animal positron-emission tomography/computed tomography (PET/CT) scanners provide anatomical and molecular imaging, which enables the joint visualization and analysis of both types of data. A proper alignment calibration procedure is essential for small-animal imaging since resolution is much higher than that in human devices. This work presents an alignment phantom and two different calibration methods that provide a reliable and repeatable measurement of the spatial geometrical alignment between the PET and the CT subsystems of a hybrid scanner. The phantom can be built using laboratory materials, and it is meant to estimate the rigid spatial transformation that aligns both modalities. It consists of three glass capillaries filled with a positron-emitter solution and positioned in a non-coplanar triangular geometry inside the system field of view. The calibration methods proposed are both based on automatic line detection, but with different approaches to calculate the transformation of the lines between both modalities. Our results show an average accuracy of the alignment estimation of 0.39 mm over the whole field of view.

On the possibility of non-invasive multilayer temperature estimation using soft-computing methods.

OBJECTIVE AND MOTIVATION: This work reports original results on the possibility of non-invasive temperature estimation (NITE) in a multilayered phantom by applying soft-computing methods. The existence of reliable non-invasive temperature estimator models would improve the security and efficacy of thermal therapies. These points would lead to a broader acceptance of this kind of therapies. Several approaches based on medical imaging technologies were proposed, magnetic resonance imaging (MRI) being appointed as the only one to achieve the acceptable temperature resolutions for hyperthermia purposes. However, MRI intrinsic characteristics (e.g., high instrumentation cost) lead us to use backscattered ultrasound (BSU). Among the different BSU features, temporal echo-shifts have received a major attention. These shifts are due to changes of speed-of-sound and expansion of the medium. NOVELTY ASPECTS: The originality of this work involves two aspects: the estimator model itself is original (based on soft-computing methods) and the application to temperature estimation in a three-layer phantom is also not reported in literature. MATERIALS AND METHODS: In this work a three-layer (non-homogeneous) phantom was developed. The two external layers were composed of (in % of weight): 86.5% degassed water, 11% glycerin and 2.5% agar-agar. The intermediate layer was obtained by adding graphite powder in the amount of 2% of the water weight to the above composition. The phantom was developed to have attenuation and speed-of-sound similar to in vivo muscle, according to the literature. BSU signals were collected and cumulative temporal echo-shifts computed. These shifts and the past temperature values were then considered as possible estimators inputs. A soft-computing methodology was applied to look for appropriate multilayered temperature estimators. The methodology involves radial-basis functions neural networks (RBFNN) with structure optimized by the multi-objective genetic algorithm (MOGA). In this work 40 operating conditions were considered, i.e. five 5-mm spaced spatial points and eight therapeutic intensities (I(SATA)): 0.3, 0.5, 0.7, 1.0, 1.3, 1.5, 1.7 and 2.0W/cm(2). Models were trained and selected to estimate temperature at only four intensities, then during the validation phase, the best-fitted models were analyzed in data collected at the eight intensities. This procedure leads to a more realistic evaluation of the generalisation level of the best-obtained structures. RESULTS AND DISCUSSION: At the end of the identification phase, 82 (preferable) estimator models were achieved. The majority of them present an average maximum absolute error (MAE) inferior to 0.5 degrees C. The best-fitted estimator presents a MAE of only 0.4 degrees C for both the 40 operating conditions. This means that the gold-standard maximum error (0.5 degrees C) pointed for hyperthermia was fulfilled independently of the intensity and spatial position considered, showing the improved generalisation capacity of the identified estimator models. As the majority of the preferable estimator models, the best one presents 6 inputs and 11 neurons. In addition to the appropriate error performance, the estimator models present also a reduced computational complexity and then the possibility to be applied in real-time. CONCLUSIONS: A non-invasive temperature estimation model, based on soft-computing technique, was proposed for a three-layered phantom. The best-achieved estimator models presented an appropriate error performance regardless of the spatial point considered (inside or at the interface of the layers) and of the intensity applied. Other methodologies published so far, estimate temperature only in homogeneous media. The main drawback of the proposed methodology is the necessity of a-priory knowledge of the temperature behavior. Data used for training and optimisation should be representative, i.e., they should cover all possible physical situations of the estimation environment.

Design and performance evaluation of a coplanar multimodality scanner for rodent imaging.

This work reports on the development and performance evaluation of the VrPET/CT, a new multimodality scanner with coplanar geometry for in vivo rodent imaging. The scanner design is based on a partial-ring PET system and a small-animal CT assembled on a rotatory gantry without axial displacement between the geometric centers of both fields of view (FOV). We report on the PET system performance based on the NEMA NU-4 protocol; the performance characteristics of the CT component are not included herein. The accuracy of inter-modality alignment and the imaging capability of the whole system are also evaluated on phantom and animal studies. Tangential spatial resolution of PET images ranged between 1.56 mm at the center of the FOV and 2.46 at a radial offset of 3.5 cm. The radial resolution varies from 1.48 mm to 1.88 mm, and the axial resolution from 2.34 mm to 3.38 mm for the same positions. The energy resolution was 16.5% on average for the entire system. The absolute coincidence sensitivity is 2.2% for a 100-700 keV energy window with a 3.8 ns coincident window. The scatter fraction values for the same settings were 11.45% for a mouse-sized phantom and 23.26% for a rat-sized phantom. The peak noise equivalent count rates were also evaluated for those phantoms obtaining 70.8 kcps at 0.66 MBq/cc and 31.5 kcps at 0.11 MBq/cc, respectively. The accuracy of inter-modality alignment is below half the PET resolution, and the image quality of biological specimens agrees with measured performance parameters. The assessment presented in this study shows that the VrPET/CT system is a good performance small-animal imager, while the cost derived from a partial ring detection system is substantially reduced as compared with a full-ring PET tomograph.

Extraction of the respiratory signal from small-animal CT projections for a retrospective gating method.

We propose a retrospective respiratory gating algorithm to generate dynamic CT studies. To this end, we compared three different methods of extracting the respiratory signal from the projections of small-animal cone-beam computed tomography (CBCT) scanners. Given a set of frames acquired from a certain axial angle, subtraction of their average image from each individual frame produces a set of difference images. Pixels in these images have positive or negative values (according to the respiratory phase) in those areas where there is lung movement. The respiratory signals were extracted by analysing the shape of the histogram of these difference images: we calculated the first four central and non-central moments. However, only odd-order moments produced the desired breathing signal, as the even-order moments lacked information about the phase. Each of these curves was compared to a reference signal recorded by means of a pneumatic pillow. Given the similar correlation coefficients yielded by all of them, we selected the mean to implement our retrospective protocol. Respiratory phase bins were separated, reconstructed independently and included in a dynamic sequence, suitable for cine playback. We validated our method in five adult rat studies by comparing profiles drawn across the diaphragm dome, with and without retrospective respiratory gating. Results showed a sharper transition in the gated reconstruction, with an average slope improvement of 60.7%.