Identification of genomic regions, genetic variants and gene networks regulating candidate genes for lipid metabolism in pig muscle.

The intramuscular fat content and fatty acid composition of porcine meat have a significant impact on its quality and nutritional value. This research aimed to investigate the expression of 45 genes involved in lipid metabolism in the longissimus dorsi muscle of three experimental pig backcrosses, with a 25% of Iberian background. To achieve this objective, we conducted an expression Genome-Wide Association Study (eGWAS) using gene expression levels in muscle measured by high-throughput real-time qPCR for 45 target genes and genotypes from the PorcineSNP60 BeadChip or Axiom Porcine Genotyping Array and 65 single nucleotide polymorphisms (SNPs) located in 20 genes genotyped by a custom-designed Taqman OpenArray in a cohort of 354 animals. The eGWAS analysis identified 301 eSNPs associated with 18 candidate genes (ANK2, APOE, ARNT, CIITA, CPT1A, EGF, ELOVL6, ELOVL7, FADS3, FASN, GPAT3, NR1D2, NR1H2, PLIN1, PPAP2A, RORA, RXRA and UCP3). Three cis-eQTL (expression quantitative trait loci) were identified for GPAT3, RXRA, and UCP3 genes, which indicates that a genetic polymorphism proximal to the same gene is affecting its expression. Furthermore, 24 trans-eQTLs were detected, and eight candidate regulatory genes were located in these genomic regions. Additionally, two trans-regulatory hotspots in Sus scrofa chromosomes 13 and 15 were identified. Moreover, a co-expression analysis performed on 89 candidate genes and the fatty acid composition revealed the regulatory role of four genes (FABP5, PPARG, SCD, and SREBF1). These genes modulate the levels of α-linolenic, arachidonic, and oleic acids, as well as regulating the expression of other candidate genes associated with lipid metabolism. The findings of this study offer novel insights into the functional regulatory mechanism of genes involved in lipid metabolism, thereby enhancing our understanding of this complex biological process.

The O-RADS MRI score for the characterization of indeterminate ovarian masses: From theory to practice.

This article reviews the Ovarian-Adnexal Reporting Data System Magnetic Resonance Imaging (O-RADS MRI) score for the characterization of indeterminate ovarian masses. We aim to provide sufficient information to enable readers to apply the score efficiently in clinical practice. To this end, we review the indications of the O-RADS MRI score and the specific MRI protocol that must be applied. We review all the categories of the score, illustrating them through examples. Finally, we show the most common errors and pitfalls during the learning curve, providing the keys to avoiding them.

La clasificación O-RADS RM para caracterización de las masas ováricas indeterminadas. De la teoría a la práctica / The O-RADS MRI score for the characterization of indeterminate ovarian masses: from theory to practice

El propósito de este artículo es revisar la clasificación Ovarian-Adnexal Reporting Data System Magnetic Resonance Imaging (O-RADS RM) para caracterización de masas ováricas indeterminadas. Nuestro objetivo es que al final de la lectura de este artículo el lector tenga un conocimiento suficiente de dicha clasificación para poderla aplicar en la práctica clínica de forma eficiente.Para ello, revisaremos las indicaciones de la clasificación O-RADS RM y el protocolo de RM específico que debe realizarse. Repasaremos todas las categorías de la clasificación aportando ejemplos ilustrativos. Por último, mostraremos los errores más frecuentes que aparecen durante la curva de aprendizaje y daremos las claves para subsanarlos.(AU)

This article reviews the Ovarian-Adnexal Reporting Data System Magnetic Resonance Imaging (O-RADS MRI) score for the characterization of indeterminate ovarian masses. We aim to provide sufficient information to enable readers to apply the score efficiently in clinical practice.To this end, we review the indications of the O-RADS MRI score and the specific MRI protocol that must be applied. We review all the categories of the score, illustrating them through examples. Finally, we show the most common errors and pitfalls during the learning curve, providing the keys to avoiding them.(AU)

Profilaxis de la lesión renal aguda poscontraste (LRA-PC). Actualización según la guía clínica ESUR 10.0 y revisión crítica / Prophylaxis against postcontrast acute kidney injury (PC-AKI): updates in the ESUR guidelines 10.0 and critical review

La European Society of Urogenital Radiology (ESUR) ha actualizado la guía de profilaxis de la lesión renal aguda poscontraste (LRA-PC) yodado en 2018, guía ESUR 10.0. Esta guía reduce drásticamente las indicaciones de la realización de la profilaxis de la LRA-PC yodado, rebajando el dintel de realización de profilaxis a filtrados glomerulares menores de 30 ml/min/1,73m2 y eliminando la mayoría de los considerados factores de riesgo previamente. En los casos en que se considera necesario, las pautas de hidratación indicadas son más cortas que en la guía previa. Esta guía ha sido suscrita por la mayoría de las sociedades radiológicas, pero también ha sido criticada por su excesiva relajación en cuanto a los factores de riesgo, especialmente por la comunidad nefrológica. En este artículo revisamos los cambios que supone esta guía en relación con la anterior y planteamos las críticas a la misma

The European Society of Urogenital Radiology (ESUR) updated its guidelines for prophylaxis against postcontrast acute kidney injury (PC-AKI) in 2018 (ESUR 10.0). These guidelines drastically reduce the indications for prophylaxis against PC-AKI after iodine-based contrast administration, lowering the cutoff for administering prophylaxis to glomerular filtration rates <30ml/min/1.73m2 and eliminating most of the prior risk factors. Moreover, in cases where prophylaxis is considered necessary, the periods of hydration are shorter than in the previous version. These guidelines have been approved by most radiological societies, although they have also been criticized for excessive relaxation regarding risk factors, especially by the nephrological community. In this article, we critically review the changes to the guidelines

Prophylaxis against postcontrast acute kidney injury (PC-AKI): updates in the ESUR guidelines 10.0 and critical review. / Profilaxis de la lesión renal aguda poscontraste (LRA-PC). Actualización según la guía clínica ESUR 10.0 y revisión crítica.

The European Society of Urogenital Radiology (ESUR) updated its guidelines for prophylaxis against postcontrast acute kidney injury (PC-AKI) in 2018 (ESUR 10.0). These guidelines drastically reduce the indications for prophylaxis against PC-AKI after iodine-based contrast administration, lowering the cutoff for administering prophylaxis to glomerular filtration rates <30ml/min/1.73m2 and eliminating most of the prior risk factors. Moreover, in cases where prophylaxis is considered necessary, the periods of hydration are shorter than in the previous version. These guidelines have been approved by most radiological societies, although they have also been criticized for excessive relaxation regarding risk factors, especially by the nephrological community. In this article, we critically review the changes to the guidelines.

Manejo de la lesión renal focal incidental / Managing focal incidental renal lesions

La aparición de una lesión renal incidental ocurre con relativa frecuencia en la práctica radiológica diaria. Ante una lesión incidental deben conocerse las diferentes posibilidades diagnósticas dependiendo de si la lesión es de apariencia quística o sólida. El manejo de las lesiones quísticas viene determinado por la clasificación de Bosniak, mientras que el manejo de las lesiones sólidas trata de diferenciar entre el cáncer renal y tumores benignos, como el angiomiolipoma pobre en grasa y el oncocitoma. El radiólogo debe conocer las recomendaciones en el manejo de dichas lesiones y la utilidad de las diferentes técnicas por imagen e intervencionistas que se pueden realizar en función de las características de la lesión incidental y de las expectativas de vida del paciente (AU)

Incidental renal lesions are relatively common in daily radiological practice. It is important to know the different diagnostic possibilities for incidentally detected lesions, depending on whether they are cystic or solid. The management of cystic lesions is guided by the Bosniak classification. In solid lesions, the goal is to differentiate between renal cancer and benign tumors such as fat-poor angiomyolipoma and oncocytoma. Radiologists need to know the recommendations for the management of these lesions and the usefulness of the different imaging techniques and interventional procedures in function of the characteristics of the incidental lesion and the patient's life expectancy (AU)

Utilidad de la tomografía computarizada de doble energía con un programa específico para la identificación de litiasis renales de ácido úrico / Usefulness of dual-energy computed tomography with and without dedicated software in identifying uric acid kidney stones

Objetivo. Valorar de manera prospectiva e in vivo la identificación de litiasis renales de ácido úrico con tomografía computarizada (TC) de doble energía (TCDE) con y sin software específico. Material y métodos. Se estudiaron 65 litiasis de 63 pacientes analizadas ex vivo con espectrofotometría y que habían sido estudiadas con una TCDE. Se valoró el rendimiento diagnóstico en identificar litiasis de ácido úrico con TCDE mediante el análisis de las densidades radiológicas de las litiasis utilizando el software específico, o sin utilizarlo (midiéndolo manualmente), y mediante el análisis de las ratios de densidad de las litiasis en ambas energías con o sin el software específico. Resultados. Las seis litiasis de ácido úrico incluidas fueron correctamente identificadas mediante la valoración de la ratio de densidades con un punto de corte de 1,21, tanto con el software específico como sin él, con un rendimiento diagnóstico perfecto, sin presencia de falsos positivos ni negativos. El estudio de densidades de las litiasis obtuvo valores de las curvas COR en clasificación de litiasis de ácido úrico de 0,92 para medición con la aplicación informática y de 0,89 para las mediciones manuales y una precisión diagnóstica del 84% (42/50) con el software y del 83,1% (54/65) para las mediciones manuales para un punto de corte de 538 UH. Conclusiones. El estudio de litiasis con TCDE permite identificar correctamente las litiasis de ácido úrico mediante el cálculo de la ratio de densidades en ambas energías. Los resultados obtenidos con y sin software específico son similares (AU)

Objective. To prospectively evaluate the usefulness of dual-energy computed tomography (DECT) with and without dedicated software in identifying uric acid kidney stones in vivo. Material and methods. We studied 65 kidney stones in 63 patients. All stones were analyzed in vivo by DECT and ex vivo by spectrophotometry. We evaluated the diagnostic performance in identifying uric acid stones with DECT by analyzing the radiologic densities with dedicated software and without using it (through manual measurements) as well as by analyzing the attenuation ratios of the stones in both energies with and without the dedicated software. Results. The six uric acid stones included were correctly identified by evaluating the attenuation ratios with a cutoff of 1.21, both with the dedicated software and without it, yielding perfect diagnostic performance without false positives or false negatives. The study of the attenuations of the stones obtained the following values on the receiver operating characteristic curves in the classification of the uric acid stones: 0.92 for the measurements done with the software and 0.89 for the manual measurements; a cutoff of 538 HU yielded 84% (42/50) diagnostic accuracy for the software and 83.1% (54/65) for the manual measurements. Conclusions. DECT enabled the uric acid stones to be identified correctly through the calculation of the ratio of the attenuations in the two energies. The results obtained with the dedicated software were similar to those obtained manually (AU)

[Managing focal incidental renal lesions]. / Manejo de la lesión renal focal incidental.

Incidental renal lesions are relatively common in daily radiological practice. It is important to know the different diagnostic possibilities for incidentally detected lesions, depending on whether they are cystic or solid. The management of cystic lesions is guided by the Bosniak classification. In solid lesions, the goal is to differentiate between renal cancer and benign tumors such as fat-poor angiomyolipoma and oncocytoma. Radiologists need to know the recommendations for the management of these lesions and the usefulness of the different imaging techniques and interventional procedures in function of the characteristics of the incidental lesion and the patient's life expectancy.

Usefulness of dual-energy computed tomography with and without dedicated software in identifying uric acid kidney stones.

OBJECTIVE: To prospectively evaluate the usefulness of dual-energy computed tomography (DECT) with and without dedicated software in identifying uric acid kidney stones in vivo. MATERIAL AND METHODS: We studied 65 kidney stones in 63 patients. All stones were analyzed in vivo by DECT and ex vivo by spectrophotometry. We evaluated the diagnostic performance in identifying uric acid stones with DECT by analyzing the radiologic densities with dedicated software and without using it (through manual measurements) as well as by analyzing the attenuation ratios of the stones in both energies with and without the dedicated software. RESULTS: The six uric acid stones included were correctly identified by evaluating the attenuation ratios with a cutoff of 1.21, both with the dedicated software and without it, yielding perfect diagnostic performance without false positives or false negatives. The study of the attenuations of the stones obtained the following values on the receiver operating characteristic curves in the classification of the uric acid stones: 0.92 for the measurements done with the software and 0.89 for the manual measurements; a cutoff of 538 HU yielded 84% (42/50) diagnostic accuracy for the software and 83.1% (54/65) for the manual measurements. CONCLUSIONS: DECT enabled the uric acid stones to be identified correctly through the calculation of the ratio of the attenuations in the two energies. The results obtained with the dedicated software were similar to those obtained manually.

Cuantificación de la señal T2 pulmonar por resonancia magnética como factor pronóstico en las hernias diafragmáticas congénitas fetales / Prognostic usefulness of derived T2-weighted fetal magnetic resonance imaging measurements in congenital diaphragmatic hernia

Objetivo: Determinar el pronóstico neonatal de la hernia diafragmática congénita (HDC) partiendo de la señal relativa del pulmón contralateral en secuencias rápidas T2 de resonancia magnética (RM) fetal. Material y métodos: Estudiamos mediante ecografía y RM 28 fetos afectos de HDC y valoramos retrospectivamente en la ecografía fetal la relación entre el cociente observado y el esperado del diámetro axial máximo del pulmón dividido por el perímetro craneal (O/E LHR) y la posición hepática, y en la RM fetal el cociente de señal pulmón/hígado (LLSR) y el cociente de señal pulmón/líquido cefalorraquídeo (L/SF SR). Para determinar su valor pronóstico, los comparamos con los parámetros posnatales: supervivencia, hipertensión pulmonar, necesidad de oxígeno y la necesidad de oxigenación con membrana extracorpórea. Resultados: Encontramos diferencias significativas entre O/E LHR y la necesidad de oxigenación con membrana extracorpórea posnatal (p = 0,033) y la supervivencia posnatal (p = 0,01), y entre el LLSR de los fetos que sobrevivieron más de 45 días y los que no, con unas medianas de 1,91 y 2,56 respectivamente (p = 0,039). Conclusiones: El LLSR se correlaciona con la supervivencia posnatal en fetos con HDC y puede potencialmente utilizarse como parámetro pronóstico de la HDC fetal (AU)

Objective: To determine the usefulness of various parameters based on T2-weighted fetal magnetic resonance (MR) imaging measurements of the uninvolved lung for the neonatal prognosis of congenital diaphragmatic hernia (CDH). Material and methods: We used ultrasonography and MR imaging to study 28 fetuses with CDH. We retrospectively analyzed a) on fetal ultrasonography, the observed-to-expected lung to head ratio (O/E LHR) and the position of the liver, and b) on fetal MR imaging, the lung-liver signal ratio (LLSR) and the lungcerebrospinal fluid ratio (L/CSF SR). To determine the prognostic value of these parameters, we compared them with the following postnatal parameters: survival, pulmonary hypertension, need for oxygen supplementation, and need for extracorporeal membrane oxygenation. Results: We found significant differences between O/E LHR and the need for postnatal extracorporeal membrane oxygenation (P = .033) and postnatal survival (P = .01). We also found significant differences in LLSR between fetuses that survived more than 45 days and those that died within 45 days (1.91 vs. 2.56; P = .039). Conclusions: In fetuses with CDH, the LLSR correlates with postnatal survival and can potentially be used as a prognostic parameter in CDH (AU)

Prognostic usefulness of derived T2-weighted fetal magnetic resonance imaging measurements in congenital diaphragmatic hernia.

OBJECTIVE: To determine the usefulness of various parameters based on T2-weighted fetal magnetic resonance (MR) imaging measurements of the uninvolved lung for the neonatal prognosis of congenital diaphragmatic hernia (CDH). MATERIAL AND METHODS: We used ultrasonography and MR imaging to study 28 fetuses with CDH. We retrospectively analyzed a) on fetal ultrasonography, the observed-to-expected lung to head ratio (O/E LHR) and the position of the liver, and b) on fetal MR imaging, the lung-liver signal ratio (LLSR) and the lungcerebrospinal fluid ratio (L/CSF SR). To determine the prognostic value of these parameters, we compared them with the following postnatal parameters: survival, pulmonary hypertension, need for oxygen supplementation, and need for extracorporeal membrane oxygenation. RESULTS: We found significant differences between O/E LHR and the need for postnatal extracorporeal membrane oxygenation (P=.033) and postnatal survival (P=.01). We also found significant differences in LLSR between fetuses that survived more than 45 days and those that died within 45 days (1.91 vs. 2.56; P=.039). CONCLUSIONS: In fetuses with CDH, the LLSR correlates with postnatal survival and can potentially be used as a prognostic parameter in CDH.

Valoración radiológica de la hernia diafragmática congénita fetal / Fetal magnetic resonance imaging evaluation of congenital diaphragmatic hernia

La hernia diafragmática se define como la entrada de vísceras abdominales en la cavidad torácica a través de un orificio normal o patológico del diafragma. La compresión que las vísceras herniadas ejercen sobre los pulmones produce hipoplasia pulmonar y, secundariamente, hipertensión pulmonar, que son las causas principales de muerte neonatal en los pacientes con hernia diafragmática congénita. En la práctica clínica la entidad se diagnostica mediante ecografía. La resonancia magnética fetal se utiliza básicamente para constatar la localización torácica o abdominal del hígado, aunque también puede aportar datos sobre el resto de estructuras herniadas y la hipoplasia pulmonar. El objetivo de este artículo es revisar los hallazgos por resonancia magnética fetal de la hernia diafragmática congénita y los signos radiológicos que nos permiten establecer el pronóstico neonatal valorando la hipoplasia pulmonar (AU)

A diaphragmatic hernia is defined as the protrusion of abdominal viscera into the thoracic cavity through a normal or pathological orifice. The herniated viscera compress the lungs, resulting in pulmonary hypoplasia and secondary pulmonary hypertension, which are the leading causes of neonatal death in patients with congenital diaphragmatic hernia. Congenital diaphragmatic hernia is diagnosed by sonography in routine prenatal screening. Although magnetic resonance imaging is fundamentally used to determine whether the liver is located within the abdomen or has herniated into the thorax, it also can provide useful information about other herniated structures and the degree of pulmonary hypoplasia. The aim of this article is to review the fetal magnetic resonance findings for congenital diaphragmatic hernia and the signs that enable us to establish the neonatal prognosis when evaluating pulmonary hypoplasia (AU)

[Fetal magnetic resonance imaging evaluation of congenital diaphragmatic hernia]. / Valoración radiológica de la hernia diafragmática congénita fetal.

A diaphragmatic hernia is defined as the protrusion of abdominal viscera into the thoracic cavity through a normal or pathological orifice. The herniated viscera compress the lungs, resulting in pulmonary hypoplasia and secondary pulmonary hypertension, which are the leading causes of neonatal death in patients with congenital diaphragmatic hernia. Congenital diaphragmatic hernia is diagnosed by sonography in routine prenatal screening. Although magnetic resonance imaging is fundamentally used to determine whether the liver is located within the abdomen or has herniated into the thorax, it also can provide useful information about other herniated structures and the degree of pulmonary hypoplasia. The aim of this article is to review the fetal magnetic resonance findings for congenital diaphragmatic hernia and the signs that enable us to establish the neonatal prognosis when evaluating pulmonary hypoplasia.

Predictive value of small ulcers in the evolution of acute type B intramural hematoma.

OBJECTIVE: To assess the long-term evolution and predictive factors of type B intramural hematoma (IMH). MATERIAL AND METHODS: 34 patients (33 men), mean age: 67 years (47-87) diagnosed with type B IMH by computed tomography (CT) and followed up clinically and by CT yearly. Mean follow-up was 5.9 years (2-13 years). Two evolution patterns were considered: (a) regression and (b) progression. Clinical and imaging variables were analyzed for assessing their predictor values. RESULTS: Evolution at one year was to regression in 56% and to progression in 44% of cases. There were no association among age, sex, other aortic abnormalities, presence of atherosclerotic disease or blood pressure, initial maximum aortic diameter, indexed maximum aortic diameter, IMH thickness or length, presence or absence of mediastinal hematoma and the evolution of type B IMH. Ten patients had small aortic ulcers in the acute phase. The presence of ulcers was related with progression of IMH. No differences were observed in evolution between the control at first year and the last control. CONCLUSIONS: The presence of small ulcers is a strong predictor of evolution in acute type B IMH. In addition, the regression group remains completely stable after the first year of evolution.

Accuracy of contrast-enhanced ultrasound in the detection of bladder cancer.

OBJECTIVE: To assess the accuracy contrast-enhanced ultrasound (CEUS) in bladder cancer detection using transurethral biopsy in conventional cystoscopy as the reference standard and to determine whether CEUS improves the bladder cancer detection rate of baseline ultrasound. METHODS: 43 patients with suspected bladder cancer underwent conventional cystoscopy with transurethral biopsy of the suspicious lesions. 64 bladder cancers were confirmed in 33 out of 43 patients. Baseline ultrasound and CEUS were performed the day before surgery and the accuracy of both techniques for bladder cancer detection and number of detected tumours were analysed and compared with the final diagnosis. RESULTS: CEUS was significantly more accurate than ultrasound in determining presence or absence of bladder cancer: 88.37% vs 72.09%. Seven of eight uncertain baseline ultrasound results were correctly diagnosed using CEUS. CEUS sensitivity was also better than that of baseline ultrasound per number of tumours: 65.62% vs 60.93%. CEUS sensitivity for bladder cancer detection was very high for tumours larger than 5 mm (94.7%) but very low for tumours <5 mm (20%) and also had a very low negative predictive value (28.57%) in tumours <5 mm. CONCLUSION: CEUS provided higher accuracy than baseline ultrasound for bladder cancer detection, being especially useful in non-conclusive baseline ultrasound studies.

The glyoxylate cycle in an arbuscular mycorrhizal fungus. Carbon flux and gene expression.

The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Lipid, which is the dominant form of stored carbon in the fungal partner and which fuels spore germination, is made by the fungus within the root and is exported to the extraradical mycelium. We tested the hypothesis that the glyoxylate cycle is central to the flow of carbon in the AM symbiosis. The results of (13)C labeling of germinating spores and extraradical mycelium with (13)C(2)-acetate and (13)C(2)-glycerol and analysis by nuclear magnetic resonance spectroscopy indicate that there are very substantial fluxes through the glyoxylate cycle in the fungal partner. Full-length sequences obtained by polymerase chain reaction from a cDNA library from germinating spores of the AM fungus Glomus intraradices showed strong homology to gene sequences for isocitrate lyase and malate synthase from plants and other fungal species. Quantitative real-time polymerase chain reaction measurements show that these genes are expressed at significant levels during the symbiosis. Glyoxysome-like bodies were observed by electron microscopy in fungal structures where the glyoxylate cycle is expected to be active, which is consistent with the presence in both enzyme sequences of motifs associated with glyoxysomal targeting. We also identified among several hundred expressed sequence tags several enzymes of primary metabolism whose expression during spore germination is consistent with previous labeling studies and with fluxes into and out of the glyoxylate cycle.

Helical CT in renal transplantation: normal findings and early and late complications.

Over a 5-year period, 346 helical computed tomographic (CT) studies were performed in renal transplant recipients. Helical CT proved useful in this context by depicting parenchymal, perirenal, renal sinus, pyeloureteral, and vascular complications in great detail. CT often delineates fluid collections and their anatomic relationship to adjacent structures better than ultrasonography (US), particularly in obese patients. CT-guided puncture and drainage can be performed in cases in which US is deemed inadequate. CT angiography can depict arterial diseases such as stenosis, thrombosis, arteriovenous fistulas, aneurysms, and pseudoaneurysms in the graft artery and in the recipient iliac arterial system, thereby obviating conventional angiography in some cases. Helical CT with three-dimensional image reformatting allows accurate imaging of the entire course of ureteral and periureteral diseases (eg, hydronephrosis, ureteral leak and stricture, pyeloureteral obstruction). CT can be used in the confirmation and staging of malignancies of the renal parenchyma and urothelium. It is also helpful in evaluating associated disease in the native kidneys, acute and chronic rejection, graft embolization, and end-stage disease. Although US and nuclear medicine examination are the imaging modalities of choice in renal transplantation, helical CT is a valuable alternative when these techniques are inconclusive.

Improved diagnosis of hepatic perfusion disorders: value of hepatic arterial phase imaging during helical CT.

The liver has a unique dual blood supply, which makes helical computed tomography (CT) a highly suitable technique for hepatic imaging. Helical CT allows single breath-hold scanning without motion artifacts. Because of rapid image acquisition, two-phase (hepatic arterial phase and portal venous phase) evaluation of the hepatic parenchyma is possible, improving tumor detection and tumor characterization in a single CT study. The arterial and portal venous supplies to the liver are not independent systems. There are several communications between the vessels, including transsinusoidal, transvasal, and transplexal routes. When vascular compromise occurs, there are often changes in the volume of blood flow in individual vessels and even in the direction of blood flow. These perfusion disorders can be detected with helical CT and are generally seen as an area of high attenuation on hepatic arterial phase images that returns to normal on portal venous phase images; this finding reflects increased arterial blood flow and arterioportal shunting in most cases. Familiarity with the helical CT appearances of these perfusion disorders will result in more accurate diagnosis. By recognizing these perfusion disorders, false-positive diagnosis (hypervascular tumors) or overestimation of the size of liver tumors (eg, hepatocellular carcinoma) can be avoided.

Portomesenteric vein gas: pathologic mechanisms, CT findings, and prognosis.

Portomesenteric vein gas is a rare condition whose pathogenesis is not fully understood. Portomesenteric vein gas is most commonly caused by mesenteric ischemia but may have a variety of other causes. The primary factors that favor the development of this pathologic entity are intestinal wall alterations, bowel distention, and sepsis. Portomesenteric vein gas is idiopathic in approximately 15% of cases. Advanced imaging techniques such as computed tomography (CT) have increased the sensitivity for detection of portomesenteric vein gas. At CT, portal vein gas appears as tubular areas of decreased attenuation in the liver, predominantly in the left lobe. Gas in the great mesenteric veins can easily be demonstrated with contrast material-enhanced CT, whereas gas in the small mesenteric veins appears as tubular or branched areas of decreased attenuation in the mesenteric border of the bowel. Findings of portomesenteric vein gas at CT should be carefully evaluated in the context of clinical findings. In the majority of cases, the prognosis is favorable and surgery is not required. However, when CT demonstrates portomesenteric vein gas and clinical findings suggest the presence of mesenteric ischemia, surgery is mandatory.

Aortic dissection: diagnosis and follow-up with helical CT.

Acute aortic dissection is a cardiovascular emergency that requires prompt diagnosis and treatment. Helical computed tomography (CT) allows diagnosis of acute aortic dissection with a sensitivity and specificity of nearly 100%. With helical CT, a dissection involving the ascending aorta (type A in the Stanford classification) can be differentiated from one distal to the left subclavian artery (type B). Helical CT can also be used to identify atypical forms of aortic dissection such as intramural hematoma, penetrating atherosclerotic ulcer, ruptured type B dissection, and atypical configurations of the intimal flap. Helical CT is useful in follow-up of aortic dissection by allowing assessment of early and late changes after surgery or medical treatment. Such changes include postoperative complications of type A dissection, healing of intramural hematoma, progression of intramural hematoma, and aneurysms of the true or false lumen. Helical CT can also be used to monitor potentially life-threatening ischemic complications of abdominal branch vessels.