Strengths, weaknesses, opportunities, and threat analysis of dual-energy CT in head and neck imaging.

Technological development of dual-energy computed tomography (DECT) can play an important role in head and neck area. Multiple innovative applications have evolved, optimizing images, achieving metallic artifact reduction, differentiating materials with better primary tumor delineation, thyroid cartilage and bone invasion. Furthermore, quantification algorithms allow measuring iodine concentration, reflecting the blood supply of a lesion indirectly. DECT enables acquiring images with lower radiation doses and iodine intravenous contrast load to obtain the same CT values.. However, DECT uses ionizing radiation, which does not occur with MRI, and requires long post-processing times. Artifacts on iodine maps may be a potential source of pseudolesions. Besides, photon-counting CT scanners are a promising technique that may displace some DECT advantages. A review analyzing the current status of DECT applied to head and neck imaging from the scope of strengths, weaknesses, opportunities, and threatsanalysis would be very interesting to facilitate a realistic, fact-based, data-driven look of this technique.

Análisis de las fortalezas, oportunidades, debilidades y amenazas de la tomografía computarizada de doble energía en el diagnóstico por la imagen de la cabeza y el cuello / Strengths, weaknesses, opportunities, and threat analysis of dual-energy CT in head and neck imaging

El desarrollo tecnológico de la tomografía computarizada de energía dual (TCED) en el área de la cabeza y el cuello ha supuesto un avance importante, ya que se han desarrollado múltiples aplicaciones para optimizar las imágenes y reducir los artefactos metálicos, así como para diferenciar los materiales, permitiendo una mejor delineación del tumor primario, del cartílago tiroideo y la invasión ósea. Además, los algoritmos de cuantificación permiten medir la concentración de yodo, lo que refleja el flujo de sangre que llega a una lesión de forma indirecta. Permite adquirir imágenes con menores dosis de radiación y menor cantidad de contraste yodado para obtener los mismos valores de TC. Sin embargo, utiliza radiaciones ionizantes y el posprocesamiento de las imágenes consume tiempo, y los artefactos en los mapas de yodo pueden suponer una fuente potencial de pseudolesiones. Además, los escáneres de TC con tecnología de recuento de fotones son una técnica prometedora que puede desplazar algunas de las ventajas de la TCED.Esta revisión hace un análisis de la TCED aplicada a las imágenes de cabeza y cuello desde el ámbito del análisis de las fortalezas, oportunidades, debilidades y amenazas para facilitar una visión realista, basada en datos, de esta técnica.(AU)

Technological development of dual-energy computed tomography (DECT) can play an important role in head and neck area. Multiple innovative applications have evolved, optimizing images, achieving metallic artifact reduction, differentiating materials with better primary tumor delineation, thyroid cartilage and bone invasion. Furthermore, quantification algorithms allow measuring iodine concentration, reflecting the blood supply of a lesion indirectly.DECT enables acquiring images with lower radiation doses and iodine intravenous contrast load to obtain the same CT values. However, DECT uses ionizing radiation, which does not occur with MRI, and requires long post-processing times. Artifacts on iodine maps may be a potential source of pseudolesions. Besides, photon-counting CT scanners are a promising technique that may displace some DECT advantages.A review analyzing the current status of DECT applied to head and neck imaging from the scope of strengths, weaknesses, opportunities, and threatsanalysis would be very interesting to facilitate a realistic, fact-based, data-driven look of this technique.(AU)

La columna poscirugía / The postsurgical spine

El síndrome de la columna operada fallida es la persistencia o la reaparición de dolor tras el tratamiento quirúrgico de la columna. Bajo este término se engloban diversas causas tanto mecánicas como no mecánicas. Las técnicas de imagen son herramientas imprescindibles para el control postquirúrgico y para la valoración de las potenciales complicaciones responsables del fracaso de la cirugía. El objetivo de esta revisión es por una parte que el radiólogo se familiarice con los cambios postquirúrgicos normales y por otra parte que pueda identificar los hallazgos radiológicos patológicos que están traduciendo un síndrome de la columna operada fallida. Para eso es necesario conocer el tipo de cirugía que se ha realizado en cada caso y el tiempo transcurrido desde la intervención. En las técnicas de fusión de la columna vertebral se debe evaluar el grado de fusión ósea, el material de instrumentación (tanto su posición como su integridad), el hueso sobre el que asienta, la interfase entre el implante y el hueso y los segmentos vertebrales que se encuentran adyacentes a la columna instrumentada. En las técnicas descompresivas es importante reconocer qué cambios son los esperables en un paciente operado y saber distinguirlos de la fibrosis peridural y de la recidiva herniaria. También se deben conocer los datos radiológicos de infección postquirúrgica. Se revisarán otras complicaciones, como la aracnoiditis, las colecciones líquidas postquirúrgicas y las alteraciones de los tejidos blandos adyacentes al lecho quirúrgico (AU9

Failed back surgery syndrome is the persistence or reappearance of pain after surgery on the spine. This term encompasses both mechanical and nonmechanical causes. Imaging techniques are essential in postoperative follow-up and in the evaluation of potential complications responsible for failed back surgery syndrome. This review aims to familiarize radiologists with normal postoperative changes and to help them identify the pathological imaging findings that reflect failed back surgery syndrome. To interpret the imaging findings, it is necessary to know the type of surgery performed in each case and the time elapsed since the intervention. In techniques used to fuse the vertebrae, it is essential to evaluate the degree of bone fusion, the material used (both its position and its integrity), the bone over which it lies, the interface between the implant and bone, and the vertebral segments that are adjacent to metal implants. In decompressive techniques it is important to know what changes can be expected after the intervention and to be able to distinguish them from peridural fibrosis and the recurrence of a hernia. It is also crucial to know the imaging findings for postoperative infections. Other complications are also reviewed, including arachnoiditis, postoperative fluid collections, and changes in the soft tissues adjacent to the surgical site (AU)

The postsurgical spine. / La columna poscirugía.

Failed back surgery syndrome is the persistence or reappearance of pain after surgery on the spine. This term encompasses both mechanical and nonmechanical causes. Imaging techniques are essential in postoperative follow-up and in the evaluation of potential complications responsible for failed back surgery syndrome. This review aims to familiarize radiologists with normal postoperative changes and to help them identify the pathological imaging findings that reflect failed back surgery syndrome. To interpret the imaging findings, it is necessary to know the type of surgery performed in each case and the time elapsed since the intervention. In techniques used to fuse the vertebrae, it is essential to evaluate the degree of bone fusion, the material used (both its position and its integrity), the bone over which it lies, the interface between the implant and bone, and the vertebral segments that are adjacent to metal implants. In decompressive techniques it is important to know what changes can be expected after the intervention and to be able to distinguish them from peridural fibrosis and the recurrence of a hernia. It is also crucial to know the imaging findings for postoperative infections. Other complications are also reviewed, including arachnoiditis, postoperative fluid collections, and changes in the soft tissues adjacent to the surgical site.

Energía dual y angioTC de carótidas: calidad, eliminación de hueso y dosis de radiación de 80/140 kV frente a 100/140 kV / Dual energy CT angiography of the carotid arteries: quality, bone subtraction, and radiation dosage using tube voltage 80/140 kV versus 100/140 kV

Objetivo: Estudiar las diferencias en la calidad de imagen vascular, la capacidad de eliminar el hueso y la dosis de radiación de la angio-TC de troncos supraaórticos con la técnica de energía dual utilizando dos diferentes potenciales del tubo. Material y métodos: Se revisaron retrospectivamente los estudios de angio-TC de troncos supraaórticos realizados a 46 pacientes con un equipo de TC de doble fuente de 128 cortes, tilizando 2 protocolos de voltaje diferente (80/140 kV y 100/140 kV). El posproceso se hizo con la herramienta «head bone removal». Las arterias se dividieron en 15 segmentos. En ellos se evaluó la calidad de los vasos y la capacidad de eliminar el hueso en imágenes multiplanares (MPR) y de proyección de máxima intensidad (MIP) con cada protocolo, analizando de forma separada los huesos trabecular y cortical. También se evaluó la dosis de radiación recibida. Resultados: Se realizaron 13 estudios con 80/140 kV y 33 con 100/140 kV, sin diferencias significativas entre los grupos en edad y sexo. Las diferencias fueron significativas en la calidad de los vasos en 4 segmentos, mayor en el grupo de 100/140 kV. También en este grupo fue mejor la eliminación automática de hueso cortical en MPR y MIP, y del trabecular en las imágenes MIP. La dosis de radiación (1,16 mSv con 80/140 kV y 1,59 mSv con 100/140 kV) fue significativamente mayor en el grupo de 100/140 kV. Conclusión: El potencial 100/140 kV incrementa la dosis de radiación, pero también mejora la calidad del estudio por segmentos arteriales y la eliminación de hueso (AU)

Objective: To study the differences in vascular image quality, bone subtraction, and dose of radiation of dual energy CT angiography of the supraaortic trunks using different tube voltages. Material and methods: We reviewed the CT angiograms of the supraaortic trunks in 46 patients acquired with a 128-slice dual source CT scanner using two voltage protocols (80/140 kV and 100/140 kV). The ‘‘head bone removal’’ tool was used for postprocessing. We divided the arteries into 15 segments. In each segment, we evaluated the image quality of the vessels and the effectiveness of bone removal in multiplanar reconstructions (MPR) and in maximum intensity projections (MIP) with each protocol, analyzing the trabecular and cortical bones separately.We also evaluated the dose of radiation received. Results: Of the 46 patients, 13 were studied using 80/140 kV and 33 with 100/140 kV. There were no significant differences between the two groups in age or sex. Image quality in four segments was better in the group examined with 100/140 kV. Cortical bone removal in MPR and MIP and trabecular bone removal in MIP were also better in the group examined with 100/140 kV. The dose of radiation received was significantly higher in the group examined with 100/140 kV (1.16 mSv with 80/140 kV vs. 1.59 mSv with 100/140 kV). Conclusion: Using 100/140 kV increases the dose of radiation but improves the quality of the study of arterial segments and bone subtraction (AU)

[Dual energy CT angiography of the carotid arteries: quality, bone subtraction, and radiation dosage using tube voltage 80/140 kV versus 100/140 kV]. / Energía dual y angioTC de carótidas: calidad, eliminación de hueso y dosis de radiación de 80/140 kV frente a 100/140 kV.

OBJECTIVE: To study the differences in vascular image quality, bone subtraction, and dose of radiation of dual energy CT angiography of the supraaortic trunks using different tube voltages. MATERIAL AND METHODS: We reviewed the CT angiograms of the supraaortic trunks in 46 patients acquired with a 128-slice dual source CT scanner using two voltage protocols (80/140 kV and 100/140 kV). The "head bone removal" tool was used for postprocessing. We divided the arteries into 15 segments. In each segment, we evaluated the image quality of the vessels and the effectiveness of bone removal in multiplanar reconstructions (MPR) and in maximum intensity projections (MIP) with each protocol, analyzing the trabecular and cortical bones separately. We also evaluated the dose of radiation received. RESULTS: Of the 46 patients, 13 were studied using 80/140 kV and 33 with 100/140 kV. There were no significant differences between the two groups in age or sex. Image quality in four segments was better in the group examined with 100/140 kV. Cortical bone removal in MPR and MIP and trabecular bone removal in MIP were also better in the group examined with 100/140 kV. The dose of radiation received was significantly higher in the group examined with 100/140 kV (1.16 mSv with 80/140 kV vs. 1.59 mSv with 100/140 kV). CONCLUSION: Using 100/140 kV increases the dose of radiation but improves the quality of the study of arterial segments and bone subtraction.

¿Betabloqueante oral o intravenoso en coronariografía mediante tomografía computarizada? Un estudio prospectivo y aleatorizado / Oral versus intravenous beta-blockers for computed tomography coronary angiography? A randomized controlled trial

Objetivos. Estudiar si existen diferencias en los tiempos empleados en la atención al paciente, según se utilice la vía oral o intravenosa en la administración de betabloqueantes a pacientes ambulatorios sometidos a coronariografía mediante tomografía computarizada (TC). Material y métodos. Estudio prospectivo, analítico, aleatorizado y controlado. Se distribuye a 40 pacientes con frecuencia mayor de 65 latidos por minuto en 2 grupos. En el grupo 1 se administra el betabloqueante por vía oral y en el grupo 2 por vía intravenosa. Se mide el tiempo global transcurrido desde la entrada del paciente en Radiología hasta su marcha y el tiempo parcial de ocupación de sala desde que entra hasta que sale de la sala de TC. Variables secundarias: frecuencia cardíaca, tensión arterial y número de estudios concluyentes. Resultados. La mediana (rango intercuartílico) del tiempo global fue de 120 minutos (100-150) en los 19 pacientes betabloqueados por vía oral y de 35 minutos (27,5-67,5) en los 21 pacientes con medicación intravenosa (p<0,001). El tiempo parcial de ocupación de sala fue 10 minutos (6-15) en el grupo 1 y 10 minutos (9-20) en el grupo 2 (p=0,57). El descenso de la tensión arterial media es 10 mmHg con los betabloqueantes por vía intravenosa frente a 3,3 mmHg por la vía oral (p=0,01). No se hallaron diferencias significativas en la calidad diagnóstica de las exploraciones. Conclusiones. El tiempo de atención al paciente es significativamente menor con la administración intravenosa de betabloqueantes. No se demostraron diferencias en el tiempo de ocupación de sala ni en la calidad diagnóstica (AU)

Objectives. To determine whether the time employed in the radiological management of outpatients undergoing computed tomography (CT) coronary angiography varies in function of whether oral or intravenous beta-blockers are administered. Material and methods. This was a prospective, analytical, randomized controlled trial. A total of 40 patients with heart rates greater than 65 beats per minute were randomly assigned to one of two groups. Patients in group 1 were administered oral beta-blockers and patients in group 2 were administered intravenous beta-blockers. We measured the overall time from entry to the radiology department to exit from the CT examination room. We also measured heart rate, blood pressure, and the number of conclusive studies. Results. The median (interquartile range) overall time was 120 (100-150) minutes in the 19 patients who received oral beta-blockers compared to 35 (27.5-67.5) minutes in the 21 patients who received intravenous beta-blockers (p<0.001). The median time that patients were in the CT examination room was 10 (6-15) minutes in Group 1 and 10 (9-20) minutes in Group 2 (p=0.57). The decrease in mean arterial pressure was 10 mmHg after the administration of intravenous beta-blockers compared to 3.3 mmHg after the administration of oral beta-blockers (p=0.01). No significant differences were found in the diagnostic quality of the examinations. Conclusions. The time employed in the radiological management of patients undergoing CT coronary angiography is significantly lower when beta-blockers are administered intravenously. There was no difference in the time patients were in the CT examination room or in the diagnostic quality of the examinations (AU)

[Oral versus intravenous beta-blockers for computed tomography coronary angiography? A randomized controlled trial]. / ¿Betabloqueante oral o intravenoso en coronariografía mediante tomografía computarizada? Un estudio prospectivo y aleatorizado.

OBJECTIVES: To determine whether the time employed in the radiological management of outpatients undergoing computed tomography (CT) coronary angiography varies in function of whether oral or intravenous beta-blockers are administered. MATERIAL AND METHODS: This was a prospective, analytical, randomized controlled trial. A total of 40 patients with heart rates greater than 65 beats per minute were randomly assigned to one of two groups. Patients in group 1 were administered oral beta-blockers and patients in group 2 were administered intravenous beta-blockers. We measured the overall time from entry to the radiology department to exit from the CT examination room. We also measured heart rate, blood pressure, and the number of conclusive studies. RESULTS: The median (interquartile range) overall time was 120 (100-150) minutes in the 19 patients who received oral beta-blockers compared to 35 (27.5-67.5) minutes in the 21 patients who received intravenous beta-blockers (p<0.001). The median time that patients were in the CT examination room was 10 (6-15) minutes in Group 1 and 10 (9-20) minutes in Group 2 (p = 0.57). The decrease in mean arterial pressure was 10 mmHg after the administration of intravenous beta-blockers compared to 3.3 mmHg after the administration of oral beta-blockers (p = 0.01). No significant differences were found in the diagnostic quality of the examinations. CONCLUSIONS: The time employed in the radiological management of patients undergoing CT coronary angiography is significantly lower when beta-blockers are administered intravenously. There was no difference in the time patients were in the CT examination room or in the diagnostic quality of the examinations.

[MR-arthrography of the shoulder. Description and evaluation of the technique using a US-guided pediatric spinal needle]. / RM-artrografía de hombro. Descripción y valoración de la técnica guiada con ecografía y utilizando una aguja espinal infantil.

OBJECTIVE: To describe the technique of US-guided shoulder arthrography using a pediatric needle (modified Valls- Melloni technique) and to assess its efficacy. MATERIAL AND METHODS: Descriptive study of articular puncture for 48 magnetic resonance imaging arthrographs of the shoulder in 48 consecutive patients. The puncture was performed by a radiologist without prior experience in the technique. We used an anterior approach to the shoulder, guiding the puncture using US according to the Valls-Melloni technique; however, we used a pediatric spinal needle (Yale spinal; 22G: 0.7 x 40 mm). The efficacy of the technique was evaluated using the following variables: time employed, number of attempts, extravasation of contrast outside the joint, pain reported by the patient (on a scale from 0 to 10), and immediate or late complications of the technique. RESULTS: The time required for the procedure was 15.2+/-2.6 min (mean+/-standard deviation). A single puncture sufficed in 45 patients (94%); two attempts were necessary in two patients (4%) and three in one patient (2%). Contrast extravasation outside the joint occurred only in two patients (4%). The mean pain reported was 3.6 points (confidence interval: 3.1-4). Three patients (6%) had a vasovagal reaction. No late complications were observed. CONCLUSION: US-guided shoulder arthrography using a pediatric spinal needle is fast, simple, and safe; it can be performed by any radiologist, even without prior experience in the technique.

RM-artrografía de hombro. Descripción y valoración de la técnica guiada con ecografía y utilizando una aguja espinal infantil / MR-arthrography of the shoulder. Description and evaluation of the technique using a US-guided pediatric

Objetivo. Describir la técnica de artrografía de hombro guiada con ecografía utilizando una aguja espinal infantil (técnica modificada de Valls y Melloni) y verificar su eficacia. Material y métodos. Estudio descriptivo de la técnica de punción articular en 48 artrografías de hombro mediante resonancia magnética, realizadas en 48 pacientes consecutivos. La punción la realizó un radiólogo sin experiencia previa en esta técnica. Se empleó un abordaje anterior del hombro guiando la punción mediante ecografía según la técnica de Valls y Melloni, pero utilizando una aguja espinal infantil (Yale spinal; 22G: 0,7 × 40 mm). La eficacia de la prueba se valoró mediante las variables: tiempo empleado, número de intentos, extravasación del contraste fuera de la articulación, dolor referido por el paciente (escala de 0 a 10) y complicaciones inmediatas o tardías de la técnica. Resultados. El tiempo del procedimiento fue de 15,2 ± 2,6 min (media ± desviación estándar). Se precisó una sola punción en 45 pacientes (94%); dos intentos en dos pacientes (4%) y tres en un paciente (2%). Solamente en dos pacientes existió extravasación del contraste fuera de la articulación (4%). La media del dolor referido fue de 3,6 puntos (intervalo de confianza: 3,1-4). Tres pacientes (6%) sufrieron una reacción vaso-vagal. No hubo complicaciones tardías. Conclusión. La artrografía de hombro guiada por ecografía y usando una aguja espinal infantil es una técnica rápida, sencilla y segura, que puede ser realizada por cualquier radiólogo, incluso sin experiencia previa en la técnica

Objective. To describe the technique of US-guided shoulder arthrography using a pediatric needle (modified Valls- Melloni technique) and to assess its efficacy. Material and methods. Descriptive study of articular puncture for 48 magnetic resonance imaging arthrographs of the shoulder in 48 consecutive patients. The puncture was performed by a radiologist without prior experience in the technique. We used an anterior approach to the shoulder, guiding the puncture using US according to the Valls-Melloni technique; however, we used a pediatric spinal needle (Yale spinal; 22G: 0.7 × 40 mm). The efficacy of the technique was evaluated using the following variables: time employed, number of attempts, extravasation of contrast outside the joint, pain reported by the patient (on a scale from 0 to 10), and immediate or late complications of the technique. Results. The time required for the procedure was 15.2 ± 2.6 min (mean ± standard deviation). A single puncture sufficed in 45 patients (94%); two attempts were necessary in two patients (4%) and three in one patient (2%). Contrast extravasation outside the joint occurred only in two patients (4%). The mean pain reported was 3.6 points (confidence interval: 3.1-4). Three patients (6%) had a vasovagal reaction. No late complications were observed. Conclusion. US-guided shoulder arthrography using a pediatric spinal needle is fast, simple, and safe; it can be performed by any radiologist, even without prior experience in the technique