Detectability in computed tomographic images.

The detection limitations inherent in statistically limited computed tomographic (CT) images are described through the application of signal detection theory. The detectability of large-area, low-contrast objects is shown to be chiefly dependent upon the low-frequency content of the noise power spectral density. For projection data containg uncorrelated noise, the resulting ramplike, low-frequency behavior of the noise power spectrum of CT reconstructions may be conveniently characterized by the number of noise-equivalent x-ray quanta (NEQ) detected in the projection measurements. The NEQ for a given image may be determined either from a measurement of the noise power spectrum or from the noise granularity computed with an appropriate weighting function. A measure of the efficiency of scanner dose utilization is proposed which compares the average dose to that required by an ideal scanner to obtain the same NEQ.     

High-resolution computed tomographic study of the retrotympanum

Summary The aim of this study was to define the imaging of the retrotympanum precisely by means of high-resolution CT. Based on 66 scans of petrous bones performed in 49 patients observed in an otologic department, several retrotympanic structures were studied: the pyramidal eminence, ponticulus, subiculum, chordal ridge, tympanic sinus of Proctor, sinus tympani and recess of the facial n. The variations in morphology and depth were noted as well as the relationship between the pyramid and the facial canal. In a second phase the same anatomic structures were studied in 24 temporal bones removed from embalmed cadavers and investigated with the same radiologic technique. Anatomic correlations were made for six temporal bones to confirm the general applicability of our radiologic hypotheses. In CT the pyramidal eminence was visualised in 100% of cases, the chordal ridge in 52%, the ponticulus in 63% and the subiculum in 57%. As regards the different recesses, the sinus tympani was visualised in 95% of cases, the posterior tympanic sinus of Proctor in 38%, the fossula of Grivot in 47% and the facial recess in 80%. The mean depth of the sinus tympani was 2.7 mm and that of the tympanic sinus of Proctor was 1.65 mm; the fossula of Grivot was assessed as 2.1 mm and the facial recess as 2.2 mm. A better knowledge of these sinuses and their variations will aid the surgeon, particularly in a posterior tympanotomy or a retro-facial approach.

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Étude tomodensitométrique en haute résolution du rétrotympanum — Confrontations anatomiques

Résumé Le but de ce travail était de définir avec précision en tomodensitométrie haute résolution l'imagerie du rétrotympanum. A partir de 66 TDMs des rochers réalisés chez 49 patients suivis en ORL, plusieurs structures du rétrotympanum ont été étudiées : éminence pyramidale, ponticulus, subiculum, crête cordale, sinus tympanique de proctor, sinus tympani et récessus du facial. Les variations morphologiques et de profondeur ont été notées ainsi que le rapport entre la pyramide et le canal facial. Dans un deuxième temps, à partir de 24 temporaux prélevés sur cadavres embaumés, explorés selon la même technique radiologique, les mêmes structures anatomiques ont été étudiées. Des corrélations anatomiques pour 6 temporaux ont été réalisées pour confirmer l'ensemble de nos hypothèse radiologiques. En tomodensitométrie la visibilité de l'éminence pyramidale était obtenue dans 100% des cas, celle de la crête cordale dans 52% des cas, du ponticulus dans 63% des cas et du subiculum dans 57% des cas. Pour ce qui est des différents récessus, le sinus tympani était visible dans 95% des cas, le sinus tympani de Proctor dans 38% des cas, la fossette de Grivot dans 47% des cas et le recessus du facial dans 80% des cas. La profondeur moyenne du sinus tympani était de 2.7 mm, le sinus tympani de Proctor mesurait 1.65 mm, la fossette de Grivot était évaluée à 2.1 mm et le récessus du facial à 2.2 mm. La meilleure connaissance de ces sinus et de leur variation aidera le chirurgien en particulier pour une tympanotomie postérieure ou un abord rétro-facial.

     

Novel method to calculate pulmonary compliance images in rodents from computed tomography acquired at constant pressures

Our goal was to develop a method for generating high-resolution three-dimensional pulmonary compliance images in rodents from computed tomography (CT) images acquired at a series of constant pressures in ventilated animals. One rat and one mouse were used to demonstrate this technique. A pre-clinical GE flat panel CT scanner (maximum 31 line-pairs cm(-1) resolution) was utilized for image acquisition. The thorax of each animal was imaged with breath-holds at 2, 6, 10, 14 and 18 cm H2O pressure in triplicate. A deformable image registration algorithm was applied to each pair of CT images to map corresponding tissue elements. Pulmonary compliance was calculated on a voxel by voxel basis using adjacent pairs of CT images. Triplicate imaging was used to estimate the measurement error of this technique. The 3D pulmonary compliance images revealed regional heterogeneity of compliance. The maximum total lung compliance measured 0.080 (+/-0.007) ml air per cm H2O per ml of lung and 0.039 (+/-0.004) ml air per cm H2O per ml of lung for the rat and mouse, respectively. In this study, we have demonstrated a unique method of quantifying regional lung compliance from 4 to 16 cm H2O pressure with sub-millimetre spatial resolution in rodents.     

A-Si:H/CsI(Tl) flat-panel versus computed radiography for chest imaging applications: image quality metrics measurement

Amorphous silicon (a-Si:H) flat-panel (FP) imaging systems have recently become commercially available for both chest and mammographic imaging applications. It has been shown that this new detector technology offers better image quality and various operational advantages over the computed radiography (CR) which to date has been the most widely implemented and used digital radiography technique. However, most image quality measurements reported on flat-panel systems have been performed on prototype systems in laboratories while those for CR systems were typically independently performed and reported on in separate studies. To directly compare the two technologies, we have measured the image properties for a commercial amorphous silicon/cesium iodide [a-Si:H/CsI(Tl)] flat-panel based digital chest system and a commercial CR system under clinical imaging conditions. In this paper, measurements of image quality metrics, including the modulation transfer functions (MTFs), noise power spectra (NPSs), and detective quantum efficiencies (DQEs), for the FP and CR systems are presented and compared. Methods and issues related to these measurements are discussed. The results show that the flat-panel system has slightly lower MTF but significantly higher DQEs than the CR system. The DQEs of the flat-panel system were found to increase with the exposure while those of the CR system decrease slightly with the exposure.     

Preenhanced computed tomographic findings in brain death.

A patient complying with the clinical criteria for brain death was studied by preenhanced computed tomography (CT). Preenhanced CT showed apparent increased density at the base of the brain along the course of the major arterial vessels, and abnormally dense-appearing deep venous structures, like those of contrast-enhanced CT. There was a diffuse decrease in brain density with a poorly delineated ventricular system. These CT findings were very characteristic. CT as a non-invasive method seems to be valuable in the diagnosis of brain death. The relevant literature is reviewed and mechanisms showing those CT findings are discussed.     

低氧性肺动脉高压和慢性支气管炎、肺气肿并肺动脉高压动物模型的异同

目的 比较低氧性肺动脉高压与慢性支气管炎、肺气肿并肺动脉高压动物模型的异同,为研究慢性阻塞性肺疾病中肺动脉高压形成机制提供良好的实验模型.方法 24只雄性SD大鼠随机纳入10%低氧组(A组)、慢性支气管炎、肺气肿并肺动脉高压组(B组)及正常对照组(C组),8只/组.吸入10%氧2周制作A组,气管内注入脂多糖和每天烟熏混合刺激加18%低氧制作B组模型.各组测定血气分析、肺血流动力学并对肺泡灌洗液行白细胞计数、分类.肺组织HE染色或三联染色后观测气道炎症和肺血管重构的病理形态学改变.结果 (1)与C组比较,A、B组右心室收缩压、平均肺动脉压、右心室与左心室+室间隔重量比升高,腺泡内肌化型动脉增多、管壁增厚(P＜0.05).(2)BALF分析A组白细胞总数与C组差异无显著性(P＞0.05);B组白细胞总数及中性粒细胞增多(P＜0.05).(3) A组气道炎症以上皮细胞变性坏死、黏液杯状细胞增生为主,炎细胞浸润不明显.B组气道炎症符合慢性支气管炎、肺气肿改变,管壁呈现以淋巴细胞为主的多种炎细胞浸润.结论 B组同时体现了慢性气道炎症、肺气肿改变和肺血管重构的特征,更适合用于慢性阻塞性肺疾病中肺动脉高压形成机制的研究.     

Clinical manifestations and radiological features by chest computed tomographic findings of a novel coronavirus disease-19 pneumonia among 92 patients in Japan

IntroductionThe novel coronavirus disease (COVID-19) could cause a severe acute respiratory infectious disease, showing a high mortality rate of 12–45% among cases who required intensive care unit admission. COVID-19 pneumoniaPatients and methodsFor the purpose of identifying clinical manifestations and radiological findings of COVID-19 pneumonia, we reviewed all cases of COVID-19 pneumonia which were published by the homepage of the Japanese Association for Infectious Diseases from Feb 5 2020 until April 30 2020, including our cases. All patients were diagnosed based on positive results of the novel coronavirus-real-time RT-PCR with chest computed tomography (CT) findings.ResultsA total of 92 patients were enrolled in this study. The median age was 66 years (range 16–92 years). For all, 50 (54%) were males. The most common underlying disease was hypertension in 32 (36%). Any comorbidity was seen in 60 (67%). The mortality rate was 4 (6%). In terms of clinical symptoms on an initial visit, fever and cough were confirmed in 66 (72%) and 37 (40%). Forty-three (47%) had no respiratory symptoms. As for radiological findings by chest CT scan, ground-glass opacities (GGO)s, peripheral distribution, bilateral lung involvements were seen in 88 (96%), 76 (83%) and 78 (85%), respectively.ConclusionIt is difficult to diagnose as COVID-19 pneumonia due to poor respiratory symptoms. Chest CT findings typically show GGO, peripheral and bilateral shadows. Patients should have chest CT performed if suspected for early diagnosis and therapeutic intervention, resulting in a favorable outcome and prevention of secondary nosocomial transmitted infection.     

Obstetric complications and schizophrenia: a computed tomographic study

All patients aged 16-50 years who had been discharged from the Maudsley Hospital over a 4-year period with a diagnosis of schizophrenia were ascertained retrospectively. Case records were rated blindly for a history of obstetric complications (OCs). Sixty-one patients who satisfied the RDC for schizophrenia had undergone CT scanning. Those with a definite history of OCs presented at an earlier age. In this group widening of cortical sulci and fissures was more strongly correlated with VBR than in subjects without OCs. Moreover, large VBRs when accompanied by widened cortical sulci and fissures occurred more commonly in subjects with OCs than in those without. These results support the hypothesis that OCs, or a factor associated with them, lead to brain damage of aetiological significance in some cases of schizophrenia.     

Anatomic approach to the parametrium: value of computed tomographic in vitro study compared to dissection

Summary The aim of this study is to describe the morphology of the normal parametrium by correlating the slices obtained with computed tomography of 12 female cadavers studied after intravascular injection of latex with the dissection findings in 6 of these patients. The upper limit, represented by the isthmus, was defined by the uterine a. and/or a superficial uterine v. and/or the coronary v. (Charpy). The lower limit corresponded to the insertion of the levator ani mm. at the junction of the middle and inferior thirds of the vagina. The paracervical and paravaginal tissues above the levator ani m. and medial to the pelvic fascia covering these muscles were perfectly visualized. The posterior limit, formed by the lateral ligament of the rectum and/or the sacrouterine ligaments, and the anterior limit determined by the umbilico-vesical fascia were more difficult to demonstrate. In this study the parametrium appeared as a highly vascular and essentially venous connective structure with a variable morphology dependent on the uterine position.

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Approche anatomique du paramètre : contribution de l'imagerie tomodensitométriquein vitro confrontée à la dissection

Résumé Le but de cette étude radioanatomique est de décrire la morphologie du paramètre en tomodensitométrie (TDM) en corrélant des coupes TDM de 12 cadavres féminins après injection intra-vasculaire de latex et l'aspect secondairement observé en dissection chez six d'entre eux. La limite crâniale se situant en regard de l'orifice interne du col est repérée par l'artère utérine sousligamentaire et/ou la veine utérine superficielle et/ou la veine coronaire de Charpy. La limite caudale est formée par l'insertion des muscles levator ani à la jonction tiers moyen/tiers inférieur du vagin. Le tissu para-cervical et para-vaginal au dessus de ce plan musculaire et médialement à l'aponévrose pelvienne recouvrant ceux-ci était parfaitement visualisé. La limite dorsale représentée par le ligament latéral rectal et/ou les ligaments utérosacrés ainsi que la limite ventrale définie par l'aponévrose ombilico-vésicale étaient plus difficiles à mettre en évidence. La vascularisation paramétriale est essentiellement sous-tendue par d'importants plexus veineux et un tissu conjonctif de soutien de morphologie variable dépendante de la position utérine.

     

Different sizes of centrilobular ground-glass opacities in chest high-resolution computed tomography of patients with pulmonary veno-occlusive disease and patients with pulmonary capillary hemangiomatosis

BackgroundCentrilobular ground-glass opacity (GGO) is one of the characteristic findings in chest high-resolution computed tomography (HRCT) of patients with pulmonary veno-occlusive disease (PVOD) and patients with pulmonary capillary hemangiomatosis (PCH). However, clinical differential diagnosis of these two diseases is difficult and has not been established. In order to clarify their differences, we compared the sizes of GGOs in chest HRCT and the sizes of capillary assemblies in pulmonary vascular casts between patients diagnosed pathologically with PVOD and PCH.MethodsWe evaluated chest HRCT images for four patients with idiopathic pulmonary arterial hypertension (IPAH), three patients with PVOD and three patients with PCH, and we evaluated pulmonary vascular casts of lung tissues obtained from those patients at lung transplantation or autopsy.ResultsCentrilobular GGOs in chest HRCT were observed in patients with PVOD and patients with PCH but not in patients with IPAH. We measured the longest diameter of the GGOs. The size of centrilobular GGOs was significantly larger in patients with PCH than in patients with PVOD (5.60±1.43 mm versus 2.51±0.79 mm, P<.01). We succeeded in visualization of the 3-dimensional structures of pulmonary capillary vessels obtained from the same patients with PVOD and PCH undergoing lung transplantation or autopsy and measured the diameters of capillary assemblies. The longest diameter of capillary assemblies was also significantly larger in patients with PCH than in patients with PVOD (5.44±1.71 mm versus 3.07±1.07 mm, P<.01).ConclusionMeasurement of the sizes of centrilobular GGOs in HRCT is a simple and useful method for clinical differential diagnosis of PVOD and PCH.     

Real-time 3D computed tomographic reconstruction using commodity graphics hardware

The recent emergence of various types of flat-panel x-ray detectors and C-arm gantries now enables the construction of novel imaging platforms for a wide variety of clinical applications. Many of these applications require interactive 3D image generation, which cannot be satisfied with inexpensive PC-based solutions using the CPU. We present a solution based on commodity graphics hardware (GPUs) to provide these capabilities. While GPUs have been employed for CT reconstruction before, our approach provides significant speedups by exploiting the various built-in hardwired graphics pipeline components for the most expensive CT reconstruction task, backprojection. We show that the timings so achieved are superior to those obtained when using the GPU merely as a multi-processor, without a drop in reconstruction quality. In addition, we also show how the data flow across the graphics pipeline can be optimized, by balancing the load among the pipeline components. The result is a novel streaming CT framework that conceptualizes the reconstruction process as a steady flow of data across a computing pipeline, updating the reconstruction result immediately after the projections have been acquired. Using a single PC equipped with a single high-end commodity graphics board (the Nvidia 8800 GTX), our system is able to process clinically-sized projection data at speeds meeting and exceeding the typical flat-panel detector data production rates, enabling throughput rates of 40-50 projections s(-1) for the reconstruction of 512(3) volumes.     

Diagnostic ability of Barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography

OBJECTIVES: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index), calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. METHODS: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. RESULTS: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy) met the inclusion criteria for the study. The mean Barrett's index values (+/- SD) were 64.47% +/- 6.06% and 49.44% +/- 10.94%in the groups with and without dysthyroid optic neuropathy, respectively (p<0.001). Barrett's index sensitivity ranged from 32% to 100%, and Barrett's index specificity ranged from 24% to 100%. The best combination of sensitivity and specificity was 79%/72% for BI=60% (odds ratio: 9.2). CONCLUSIONS: Barrett's Index is a useful indicator of dysthyroid optic neuropathy and may contribute to early diagnosis and treatment. Patients with a Barrett's index >60% should be carefully examined and followed for the development of dysthyroid optic neuropathy.     

The fate of traumatic subdural hygroma in serial computed tomographic scans

We reviewed serial computed tomographic (CT) scans of 58 patients with traumatic subdural hygroma (SDG) to investigate its natural history. All were re-evaluated with a special reference to the size and density of SDG. Thirty-four patients (58.6%) were managed conservatively and 24 patients (41.4%) underwent surgery. The lesion was described as remained, reduced, resolved, enlarged and changed. Means of interval from injury to diagnosis and any changes in CT were calculated. SDGs were resolved in 12 (20.7%), reduced in 15 (25.9%), remained in 10 (17.2%), enlarged in 2 (3.4%), and changed into chronic subdural hematoma (CSDH) in 19 patients (32.8%). SDG was diagnosed at 11.6 days after the injury. It was enlarged at 25.5 days, remained at 46.0 days, reduced at 59.3 days, resolved at 107.5 days, and changed into CSDH at 101.5 days in average. SDGs were developed as delayed lesions, and changed sequentially. They enlarged for a while, then reduced in size. The final path of a SDG was either resolution or CSDH formation. Nearly half of SDGs was resolved or reduced within three months, however, 61.3% of unresolved or unreduced SDG became iso- or hyperdense CSDH. These results suggest that the unresolved SDG is the precursor of CSDH.     

乙状窦后入路薄层CT图像的三维解剖学分析

目的本研究旨在利用三维重建技术和容积再现技术定位和测量乙状窦后入路重要结构之间的距离。方法对120名志愿者进行头部薄层CT扫描来得到最终结果。结果 AC的距离经测量为39.46(4.22)mm(范围,15.80~50.80 mm;95%置信区间,38.69~40.22 mm)。内耳门的直径经测量为5.39(0.77)mm(范围,3.40-8.20 mm;95%置信区间,5.25~5.53 mm)。AB的距离经测量为41.10(4.22)mm(范围,34.90~51.30 mm;95%置信区间,39.43~42.77 mm)。BC的距离经测量为5.93(1.31)mm(范围,4.10~7.50 mm;95%置信区间,5.70~6.17 mm)。垂直距离经测量为2.33(0.26)mm(范围,1.87~2.80 mm;95%置信区间,2.23~2.42 mm)。结论通过容积再现技术和更为精确的三维测量工具对乙状窦后入路中的重要解剖结构之间的距离,垂直距离以及内听道的直径进行了精准测定,并通过上述数据计算出安全距离,使医生在手术中规避风险,为手术的成功提供了保障。上述结果可以帮助定位这些结构从而可以减少手术中对神经和血管的创伤。     

The computed tomographic attenuation and the age of subdural hematomas.

The sequential change in density (attenuation coefficient) of subdural hematomas (SDHs) in computed tomography (CT) is important in understanding the pathogenesis and evolution of SDHs. We retrospectively investigated the age of SDHs by CT in 446 cases. We included 30 cases of chronic SDHs, in whom the density was directly measured in the CT. The density of acute (within 7 days) SDH was hyperdense in 98.6%, isodense in 1.1%, and hypodense in 0.3% of the cases. In subacute (8-22 days) SDHs, it was hypodense in 45.7%, isodense in 42.9%, and hyperdense in 11.4%. In chronic (over 22 days) SDHs, 86.7% was isodense and only 13.3% was hypodense. In hypodense SDHs, 64.0% was the subacute, and 73.2% of the isodense SDHs was the chronic one. The mean interval from injury to CT was 0.5 +/- 1.6 days in hyperdense SDHs, 20.9 +/- 20.7 days in hypodense SDHs, and 54.9 +/- 44.0 days in isodense SDHs. In 30 cases of chronic SDH, the average density was 38.0 +/- 6.9 Hounsfield number(H) in 20 approximately 30 days, 43.8 +/- 12.8 H in 31 approximately 60 days, 51.8 +/- 5.1 H in 61 approximately 90 days, and 44.2 +/- 8.3 H in over 90 days. The density of acute SDH is usually hyperdense. It becomes hypodense within 3 weeks. Then the density progressively increases by the repeated microhemorrhage, which is the mechanism of enlargement of chronic SDH. The density of chronic SDH increases with time up to 90 days, then decreases again after maturation of the neomembrane, which is the mechanism of spontaneous resolution.