Darstellung der Grenze zwischen dem rechten und linken Leberlappen mit 3D-Rekonstruktionen von Spiral-Computertomographien

Zusammenfassung:Hintergrund/Ziel: Die Beschreibung der funktionellen Einteilung der Leber basiert auf dem Schema von Claude de Couinaud. Die Grenze zwischen der rechten und linken Leberhälfte scheint leicht durch die Lage der mittleren Lebervene lokalisierbar. Nach der gängigen Meinung wird diese Grenze nicht durch die Trias aus Pfortader, Arterie und Gallengang überschritten. Es soll untersucht werden, ob die Lage dieser gefäßarmen Zone zwischen den Pfortaderästen benachbarter Segmente von der Lage der Grenzebene durch die mittlere Lebervene abweicht.Methode: Bei 73 Patienten wurden im Rahmen der normalen präoperativen Diagnostik dreiphasige Spiral-CT Untersuchungen durchgeführt. Aus diesen Daten wurden dreidimensionale Rekonstruktionen erzeugt und ausgewertet. Ergebnisse: In der vorliegenden Untersuchung konnte gezeigt werden, dass die mittlere Sektorengrenze unterschiedliche Positionen einnimmt, je nach welchem Gefäßsystem sie bestimmt wird. Die mittlere Sektorengrenze zeigt hierbei einen Unterschied in ihrer Lage von 14,2° im Median. An der ventralen Leberoberfläche liegt die Grenzebene nach der mittleren Lebervene damit rechts lateral der gefäßarmen Zone zwischen den Pfortaderästen.Schlussfolgerung: Der Unterschied der Grenzebenen ist in dreidimensionalen Rekonstruktionen demonstrierbar und findet Anwendung bei der Segmentzuordnung von Läsionen. Diese Rekonstruktionen erleichtern die interdisziplinäre Kommunikation und erlauben eine vereinfachte und möglicherweise präzisere Operationsplanung.

Scepticism is warranted or when the CT scan reveals to be a pitfall

We report the case of a 72-year old woman with known metastatic breast cancer who presented to the emergency department with progressive dyspnea on exertion and chest pain. The diagnosis of pulmonary embolism could be established by pulmonary scintigraphy after computed tomography and ultrasound of the lower extremities had been negative in spite of a moderate clinical pretest probability (Wells score). This case shows that even if we manage suspected pulmonary embolism using algorithms combining clinical probability, computed tomography and ultrasound we must remain aware of eventually missing the diagnosis and carry on investigating cases with elevated clinical probability.

Reliability of clinical measurement for assessing spinal fusion: An experimental sheep study

Study Design. A sheep study designed to compare the accuracy of static radiographs, dynamic radiographs, and computed tomographic (CT) scans for the assessment of thoracolumbar facet joint fusion as determined by micro-CT scanning. Objective. To determine the accuracy and reliability of conventional imaging techniques in identifying the status of thoracolumbar (T13-L1) facet joint fusion in a sheep model. Summary of Background Data. Plain radiographs are commonly used to determine the integrity of surgical arthrodesis of the thoracolumbar spine. Many previous studies of fusion success have relied solely on postoperative assessment of plain radiographs, a technique lacking sensitivity for pseudarthrosis. CT may be a more reliable technique, but is less well characterized. Methods. Eleven adult sheep were randomized to either attempted arthrodesis using autogenous bone graft and internal fixation (n = 3) or intentional pseudarthrosis (IP) using oxidized cellulose and internal fixation (n = 8). After 6 months, facet joint fusion was assessed by independent observers, using (1) plain static radiography alone, (2) additional dynamic radiographs, and (3) additional reconstructed spiral CT imaging. These assessments were correlated with high-resolution micro-CT imaging to predict the utility of the conventional imaging techniques in the estimation of fusion success. Results. The capacity of plain radiography alone to correctly predict fusion or pseudarthrosis was 43% and was not improved using plain radiography and dynamic radiography with also a 43% accuracy. Adding assessment by reformatted CT imaging to the plain radiography techniques increased the capacity to predict fusion outcome to 86% correctly. The sensitivity, specificity, and accuracy of static radiography were 0.33, 0.55, and 0.43, respectively, those of dynamic radiography were 0.46, 0.40, and 0.43, respectively, and those of radiography plus CT were 0.88, 0.85, and 0.86, respectively. Conclusion. CT-based evaluation correlated most closely with high-resolution micro-CT imaging. Neither plain static nor dynamic radiographs were able to predict fusion outcome accurately. © 2012 Lippincott Williams & Wilkins.

Lung structure and function studied by synchrotron radiation

A novel method for functional lung imaging was introduced by adapting the K-edge subtraction method (KES) to in vivo studies of small animals. In this method two synchrotron radiation energies, which bracket the K-edge of the contrast agent, are used for simultaneous recording of absorption-contrast images. Stable xenon gas is used as the contrast agent, and imaging is performed in projection or computed tomography (CT) mode. Subtraction of the two images yields the distribution of xenon, while removing practically all features due to other structures, and the xenon density can be calculated quantitatively. Because the images are recorded simultaneously, there are no movement artifacts in the subtraction image. Time resolution for a series of CT images is one image/s, which allows functional studies. Voxel size is 0.1mm3, which is an order better than in traditional lung imaging methods. KES imaging technique was used in studies of ventilation distribution and the effects of histamine-induced airway narrowing in healthy, mechanically ventilated, and anaesthetized rabbits. First, the effect of tidal volume on ventilation was studied, and the results show that an increase in tidal volume without an increase in minute ventilation results a proportional increase in regional ventilation. Second, spiral CT was used to quantify the airspace volumes in lungs in normal conditions and after histamine aerosol inhalation, and the results showed large patchy filling defects in peripheral lungs following histamine provocation. Third, the kinetics of proximal and distal airway response to histamine aerosol were examined, and the findings show that the distal airways react immediately to histamine and start to recover, while the reaction and the recovery in proximal airways is slower. Fourth, the fractal dimensions of lungs was studied, and it was found that the fractal dimension is higher at the apical part of the lungs compared to the basal part, indicating structural differences between apical and basal lung level. These results provide new insights to lung function and the effects of drug challenge studies. Nowadays the technique is available at synchrotron radiation facilities, but the compact synchrotron radiation sources are being developed, and in relatively near future the method may be used at hospitals.

A influência da espessura óssea na medição da altura da borda alveolar em imagens de tomografia computadorizada de feixe cônico e espiral

Imagens de tomografia computadorizada (TC) permitem a visualização, sem distorções ou sobreposições, do complexo maxilo-facial, principalmente do osso alveolar. Estudos demonstraram boa reprodutibilidade e precisão da mensuração da altura da borda alveolar, todavia a influência da espessura óssea ainda é pouco descrita. Através da comparação com a mensuração direta, o objetivo deste estudo foi avaliar a precisão, reprodutibilidade e a influência da espessura óssea, na mensuração da altura da borda alveolar em imagens volumétricas e imagens bidimensionais multiplanares em TC de feixe cônico (TCFC) e em TC espiral (TCE). Utilizando 10 mandíbulas secas de humanos, 57 dentes anteriores foram tomografados em equipamentos iCAT (Imaging Science International, Hatfield, PA, EUA) e Brilliance 64 canais (Philips Eletronics, Eindhoven, Holanda), ambos utilizando voxels de 0,25 mm. Através de imagens volumétricas (3D) e imagens bidimensionais (2D) de cortes multiplanares, foi comparada a mensuração da altura da borda alveolar dessas imagens com a mensuração direta nas mandíbulas, feita por vestibular e lingual, por três avaliadores, com o auxílio de um paquímetro, totalizando 114 bordas alveolares medidas. Alta reprodutibilidade intra-avaliador (0,999 a 0,902) e interavaliador (0,998 e 0,868) foi observada através do índice de correlação intraclasse (ICC). Observou-se alta correlação entre a mensuração direta e indireta da altura da borda alveolar em imagens 2D, sendo r=0,923** e 0,916**, e em imagens 3D, com r=0,929** e 0,954*, em TCFC e TCE, respectivamente. Imagens 2D superestimam a altura da borda alveolar em 0,32 e 0,49 mm e imagens 3D em 0,34 e 0,30 mm, em TCFC e TCE respectivamente. Quando o osso alveolar apresenta espessura de no mínimo 0,6 mm a média da diferença entre medidas diretas e indiretas é de 0,16 e 0,28 mm em imagens 2D e de 0,12 e 0,03 mm em imagens 3D para TCFC e TCE respectivamente, sendo que 95% do limite de concordância varia de -0,46 a 0,79 mm e -0,32 a 0,88 mm em imagens 2D, e de -0,64 a 0,67 mm e -0,57 a 0,62 mm em imagens 3D, para TCFC e TCE respectivamente. Quando o osso alveolar é mais fino do que 0,6 mm a TC é imprecisa, pois 95% do limite de concordância variou de -1,74 a 5,42 mm e -1,64 a 5,42 mm em imagens 2D, e de -3,70 a 4,28 mm e -3,49 a 4,25 mm em imagens 3D, para TCFC e TCE respectivamente. Conclui-se que a mensuração da altura da borda alveolar através de imagens tomográficas apresenta alta reprodutibilidade, sendo que quando a borda alveolar apresenta pelo menos 0,6 mm, a precisão da mensuração é alta, todavia quando esta espessura é menor do que 0,6 mm a técnica é imprecisa.

Survey radiography and computerized tomography imaging of the thorax in female dogs with mammary tumors

Background: Accurate early diagnosis of lung metastases is important for establishing therapeutic measures. Therefore, the present study aimed to compare survey thoracic radiographs and computerized tomography (CT) scans to specifically identify lung metastases in female dogs with mammary tumors.Methods: Twenty-one female dogs, weighing 3 to 34 kg and aged from 5 years to 14 years and 10 months, with mammary tumors were studied. In all dogs before the imaging examinations, fine-needle aspiration cytology of the mammary tumors was performed to confirm the diagnosis. Three-view thoracic radiographs were accomplished: right lateral, left lateral and ventrodorsal views. Sequential transverse images of the thorax were acquired on a spiral Scanner, before and after intravenous bolus injection of nonionic iodine contrast. Soft-tissue and lung windows were applied. All the mammary tumors were surgically removed and examined histologically.Results: The correlation between the cytological and histological results regarding presence of malignancy was observed in only 17 cases. In radiographic examinations, no dog displayed signs of lung metastases or thorax chest lesions. CT detected lung metastasis in two cases, while small areas of lung atelectasis located peripherally were found in 28.57% of the dogs.Conclusion: In this study population, spiral CT showed higher sensitivity than chest radiographies to detect lung metastasis; this indicates that CT should be performed on all female dogs with malignant mammary tumors.

Periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders: A computed tomography evaluation

Introduction: The force delivered during rapid maxillary expansion (RME) produces areas of compression on the periodontal ligament of the supporting teeth. The resulting alveolar bone resorption can lead to unwanted tooth movement in the same direction. The purpose of this study was to evaluate periodontal changes by means of computed tomography after RME with tooth-tissue-borne and tooth-borne expanders. Methods: The sample comprised 8 girls, 11 to 14 years old, with Class I or II malocclusions with unilateral or bilateral posterior crossbites Four girls were treated with tooth-tissue-borne Haas-type expanders, and 4 were treated with tooth-borne Hyrax expanders. The appliances were activated up to the full 7-mm capacity of the expansion screw. Spiral CT scans were taken before expansion and after the 3-month retention period when the expander was removed. One-millimeter thick axial sections were exposed parallel to the palatal plane, comprising the dentoalveolar area and the base of the maxilla up to the inferior third of the nasal cavity. Multiplanar reconstruction was used to measure buccal and lingual bone plate thickness and buccal alveolar bone crest level by means of the computerized method. Results and Conclusions: RME reduced the buccal bone plate thickness of supporting teeth 0.6 to 0.9 mm and increased the lingual bone plate thickness 0.8 to 1.3 mm. The increase in lingual bone plate thickness of the maxillary posterior teeth was greater in the tooth-borne expansion group than in the tooth-tissue-borne group. RME induced bone dehiscences on the anchorage teeth's buccal aspect (7.1 ± 4.6 mm at the first premolars and 3.8 ± 4.4 mm at the mesiobuccal area of the first molars), especially in subjects with thinner buccal bone plates. The tooth-borne expander produced greater reduction of first premolar buccal alveolar bone crest level than did the tooth-tissue-borne expander. © 2006 American Association of Orthodontists.

Current practices in the management of patients with ureteral calculi in the emergency room of a university hospital

OBJECTIVE: Urinary lithiasis is a common disease. The aim of the present study is to assess the knowledge regarding the diagnosis, treatment and recommendations given to patients with ureteral colic by professionals of an academic hospital. MATERIALS AND METHODS: Sixty-five physicians were interviewed about previous experience with guidelines regarding ureteral colic and how they manage patients with ureteral colic in regards to diagnosis, treatment and the information provided to the patients. RESULTS: Thirty-six percent of the interviewed physicians were surgeons, and 64% were clinicians. Forty-one percent of the physicians reported experience with ureterolithiasis guidelines. Seventy-two percent indicated that they use noncontrast CT scans for the diagnosis of lithiasis. All of the respondents prescribe hydration, primarily for the improvement of stone elimination (39.3%). The average number of drugs used was 3.5. The combination of nonsteroidal anti-inflammatory drugs and opioids was reported by 54% of the physicians (i. e., 59% of surgeons and 25.6% of clinicians used this combination of drugs) (p = 0.014). Only 21.3% prescribe alpha blockers. CONCLUSION: Reported experience with guidelines had little impact on several habitual practices. For example, only 21.3% of the respondents indicated that they prescribed alpha blockers; however, alpha blockers may increase stone elimination by up to 54%. Furthermore, although a meta-analysis demonstrated that hydration had no effect on the transit time of the stone or on the pain, the majority of the physicians reported that they prescribed more than 500 ml of fluid. Dipyrone, hyoscine, nonsteroidal anti-inflammatory drugs, and opioids were identified as the most frequently prescribed drug combination. The information regarding the time for the passage of urinary stones was inconsistent. The development of continuing education programs regarding ureteral colic in the emergency room is necessary.

Quantification of atelectatic lung volumes in two different porcine models of ARDS

BACKGROUND: Cyclic recruitment during mechanical ventilation contributes to ventilator associated lung injury. Two different pathomechanisms in acute respiratory distress syndrome (ARDS) are currently discussed: alveolar collapse vs persistent flooding of small airways and alveoli. We compare two different ARDS animal models by computed tomography (CT) to describe different recruitment and derecruitment mechanisms at different airway pressures: (i) lavage-ARDS, favouring alveolar collapse by surfactant depletion; and (ii) oleic acid ARDS, favouring alveolar flooding by capillary leakage. METHODS: In 12 pigs [25 (1) kg], ARDS was randomly induced, either by saline lung lavage or oleic acid (OA) injection, and 3 animals served as controls. A respiratory breathhold manoeuvre without spontaneous breathing at different continuous positive airway pressure (CPAP) was applied in random order (CPAP levels of 5, 10, 15, 30, 35 and 50 cm H(2)O) and spiral-CT scans of the total lung were acquired at each CPAP level (slice thickness=1 mm). In each spiral-CT the volume of total lung parenchyma, tissue, gas, non-aerated, well-aerated, poorly aerated, and over-aerated lung was calculated. RESULTS: In both ARDS models non-aerated lung volume decreased significantly from CPAP 5 to CPAP 50 [oleic acid lung injury (OAI): 346.9 (80.1) to 96.4 (48.8) ml, P<0.001; lavage-ARDS: 245 17.6) to 42.7 (4.8) ml, P<0.001]. In lavage-ARDS poorly aerated lung volume decreased at higher CPAP levels [232 (45.2) at CPAP 10 to 84 (19.4) ml at CPAP 50, P<0.001] whereas in OAI poorly aerated lung volume did not vary at different airway pressures. CONCLUSIONS: In both ARDS models well-aerated and non-aerated lung volume respond to different CPAP levels in a comparable fashion: Thus, a cyclical alveolar collapse seems to be part of the derecruitment process also in the OA-ARDS. In OA-ARDS, the increase in poorly aerated lung volume reflects the specific initial lesion, that is capillary leakage with interstitial and alveolar oedema.

Electroanatomic reconstruction of the left atrium, pulmonary veins, and esophagus compared with the "true anatomy" on multislice computed tomography in patients undergoing catheter ablation of atrial fibrillation

BACKGROUND: Current concepts of catheter ablation for atrial fibrillation (AF) commonly use three-dimensional (3D) reconstructions of the left atrium (LA) for orientation, catheter navigation, and ablation line placement. OBJECTIVES: The purpose of this study was to compare the 3D electroanatomic reconstruction (Carto) of the LA, pulmonary veins (PVs), and esophagus with the true anatomy displayed on multislice computed tomography (CT). METHODS: In this prospective study, 100 patients undergoing AF catheter ablation underwent contrast-enhanced spiral CT scan with barium swallow and subsequent multiplanar and 3D reconstructions. Using Carto, circumferential plus linear LA lesions were placed. The esophagus was tagged and integrated into the Carto map. RESULTS: Compared with the true anatomy on CT, the electroanatomic reconstruction accurately displayed the true distance between the lower PVs; the distances between left upper PV, left lower PV, right lower PV, and center of the esophagus; the longitudinal diameter of the encircling line around the funnel of the left PVs; and the length of the mitral isthmus line. Only the distances between the upper PVs, the distance between the right upper PV and esophagus, and the diameter of the right encircling line were significantly shorter on the electroanatomic reconstructions. Furthermore, electroanatomic tagging of the esophagus reliably visualized the true anatomic relationship to the LA. On multiple tagging and repeated CT scans, the LA and esophagus showed a stable anatomic relationship, without relevant sideward shifting of the esophagus. CONCLUSION: Electroanatomic reconstruction can display with high accuracy the true 3D anatomy of the LA and PVs in most of the regions of interest for AF catheter ablation. In addition, Carto was able to visualize the true anatomic relationship between the esophagus and LA. Both structures showed a stable anatomic relationship on Carto and CT without relevant sideward shifting of the esophagus.

Visualization of alveolar recruitment in a porcine model of unilateral lung lavage using 3He-MRI

BACKGROUND: In the acute respiratory distress syndrome potentially recruitable lung volume is currently discussed. (3)He-magnetic resonance imaging ((3)He-MRI) offers the possibility to visualize alveolar recruitment directly. METHODS: With the approval of the state animal care committee, unilateral lung damage was induced in seven anesthetized pigs by saline lavage of the right lungs. The left lung served as an intraindividual control (healthy lung). Unilateral lung damage was confirmed by conventional proton MRI and spiral-CT scanning. The total aerated lung volume was determined both at a positive end-expiratory pressure (PEEP) of 0 and 10 mbar from three-dimensionally reconstructed (3)He images, both for healthy and damaged lungs. The fractional increase of aerated volume in damaged and healthy lungs, followed by a PEEP increase from 0 to 10 mbar, was compared. RESULTS: Aerated gas space was visualized with a high spatial resolution in the three-dimensionally reconstructed (3)He-MR images, and aeration defects in the lavaged lung matched the regional distribution of atelectasis in proton MRI. After recruitment and PEEP increase, the aerated volume increased significantly both in healthy lungs from 415 ml [270-445] (median [min-max]) to 481 ml [347-523] and in lavaged lungs from 264 ml [71-424] to 424 ml [129-520]. The fractional increase in lavaged lungs was significantly larger than that in healthy lungs (healthy: 17% [11-38] vs. lavage: 42% [14-90] (P=0.031). CONCLUSION: The (3)He-MRI signal might offer an experimental approach to discriminate atelectatic vs. poor aerated lung areas in a lung damage animal model. Our results confirm the presence of potential recruitable lung volume by either alveolar collapse or alveolar flooding, in accordance with previous reports by computed tomography.

Hypothetical mortality risk associated with spiral computed tomography of the maxilla and mandible

In the present study, dose measurements have been conducted following examination of the maxilla and mandible with spiral computed tomography (CT). The measurements were carried out with 2 phantoms, a head and neck phantom and a full body phantom. The analysis of applied thermoluminescent dosimeters yielded radiation doses for organs and tissues in the head and neck region between 0.6 and 16.7 mGy when 40 axial slices and 120 kV/165 mAs were used as exposure parameters. The effective dose was calculated as 0.58 and 0.48 mSv in the maxilla and mandible, respectively. Tested methods for dose reduction showed a significant decrease of radiation dose from 40 to 65%. Based on these results, the mortality risk was estimated according to calculation models recommended by the Committee on the Biological Effects of Ionizing Radiations and by the International Commission on Radiological Protection. Both models resulted in similar values. The mortality risk ranges from 46.2 x 10.6 for 20-year-old men to 11.2 x 10(-6) for 65-year-old women. Using 2 methods of dose reduction, the mortality risk decreased by approximately 50 to 60% to 19.1 x 10(-6) for 20-year-old men and 5.5 x 10(-6) for 65-year-old women. It can be concluded that a CT scan of the maxillofacial complex causes a considerable radiation dose when compared with conventional radiographic examinations. Therefore, a careful indication for this imaging technique and dose reduction methods should be considered in daily practice.