Protocol for measurement of liver fat by computed tomography

2006 ◽  
Vol 100 (3) ◽  
pp. 864-868 ◽  
Author(s):  
Lance E. Davidson ◽  
Jennifer L. Kuk ◽  
Timothy S. Church ◽  
Robert Ross
Keyword(s):  
Computed Tomography ◽  
Liver Fat ◽  
Clinical Settings ◽  
Ct Image ◽  
Hounsfield Units ◽  
Spleen Tissue ◽  
Routine Measurement ◽  
Preliminary Study ◽  
The Difference ◽  
Attenuation Values

To develop a protocol for measurement of liver fat using computed tomography (CT), we conducted a preliminary study with 118 men and 76 women to determine a readily identifiable vertebral landmark at which the CT image displayed both liver and spleen. Analysis of five landmarks revealed that the CT image obtained at the T12–L1 level simultaneously displayed the liver and spleen in 90% of the men and women. The T12–L1 protocol was cross-validated on a sample of 130 men and 113 women. In this sample, we also assessed the regional characteristics of liver and spleen tissue attenuation at the T12–L1 level by subdividing each image into quartiles from anterior to posterior, each of which were further divided into medial and lateral regions. A similar analysis was performed on images located 12 mm above and below T12–L1. The T12–L1 image displayed both liver and spleen in 92% (403 of 437) of the combined study sample. There was a significant ( P < 0.005) stepwise increase in attenuation values [Hounsfield units (HU)] from the inferior to superior image. Although some significant ( P < 0.05) differences were observed between the eight regions by comparison to the whole liver or spleen, the average magnitude of the difference was <2.0 HU for liver and <3.5 HU for spleen. Acquisition of a single CT image at the T12–L1 level is a practical and reliable method for routine measurement of liver fat in research and clinical settings.

scholarly journals Application of Computed Tomography (CT) Attenuation Values in Diagnosis of Transudate and Exudate in Patients with Pleural Effusion

2018 ◽  
Vol 11 (02) ◽  
pp. 19-25
Author(s):  
Keshab Sharma ◽  
PS Lamichhane ◽  
BK Sharma
Keyword(s):  
Computed Tomography ◽  
Pleural Effusion ◽  
Ct Scan ◽  
Pleural Fluid ◽  
Pleural Effusions ◽  
Hounsfield Units ◽  
Fluid Analysis ◽  
Ct Attenuation ◽  
The Mean ◽  
Attenuation Values

Background: Pleural effusion is the pathologic accumulation of fluid in the pleural space. The fluid analysis yields important diagnostic information, and in certain cases, fluid analysis alone is enough for diagnosis. Analysis of pleural fluid by thoracentesis with imaging guidance helps to determine the cause of pleural effusion. The purpose of this study was to assess the accuracy of computed tomography (CT) in characterizing pleural fluid based on attenuation values and CT appearance. Materials and Methods: This prospective study included 100 patients admitted to Gandaki Medical College and Teaching Hospital, Pokhara, Nepal between January 1, 2017 and February 28, 2018. Patients who were diagnosed with pleural effusion and had a chest CT followed by diagnostic thoracentesis within 48 hours were included in the study. Effusions were classified as exudates or transudates using laboratory biochemistry markers on the basis of Light’s criteria. The mean attenuation values of the pleural effusions were measured in Hounsfield units in all patients using a region of interest with the greatest quantity of fluid. Each CT scan was also reviewed for the presence of additional pleural features. Results: According to Light’s criteria, 26 of 100 patients with pleural effusions had transudates, and the remaining patients had exudates. The mean attenuation of the exudates (16.5 ±1.7 HU; 95% CI, range, -33.4 – 44 HU) was significantly higher than the mean attenuation of the transudates (11.6 ±0.57 HU; 95% CI, range, 5 - 16 HU), (P = 0.0001). None of the additional CT features accurately differentiated exudates from transudates (P = 0.70). Fluid loculation was found in 35.13% of exudates and in 19.23% of transudates. Pleural thickening was found in 29.7% of exudates and in 15.3% of transudates. Pleural nodule was found in 10.8% of exudates which all were related to the malignancy. Conclusion: CT attenuation values may be useful in differentiating exudates from transudates. Exudates had significantly higher Hounsfield units in CT scan. Additional signs, such as fluid loculation, pleural thickness, and pleural nodules were more commonly found in patients with exudative effusions and could be considered and may provide further information for the differentiation.

Lingual dermoid cyst with congenital discharging sinus: a rare entity

2012 ◽  
Vol 127 (2) ◽  
pp. 211-214 ◽  
Author(s):  
Z Sun ◽  
L Sun ◽  
Y Gao ◽  
X Ma
Keyword(s):  
Computed Tomography ◽  
English Language ◽  
Fatty Tissue ◽  
Rare Entity ◽  
Hounsfield Units ◽  
Radiological Features ◽  
Computed Tomography Images ◽  
Attenuation Values ◽  
Congenital Fistula ◽  
Language Literature

AbstractObjective:There have been few reports of lingual dermoid cysts with a congenital discharging fistula. We report such a case, which mimicked lipoma on computed tomography, and we discuss relevant clinical and radiological features.Method:We present a case report and a review of the English language literature concerning lingual dermoid cysts either mimicking lipoma or with a congenital discharging sinus.Results:A 35-year-old man presented with a lingual mass associated with a congenital fistula in the midline of the tongue dorsum, which discharged abnormal secretions. Computed tomography images showed that the lesion was well defined and contained homogeneous fatty tissue giving computed tomography attenuation values of −120 Hounsfield units.Conclusion:Lingual dermoid cysts may develop with a midline discharging fistula, and may exhibit radiological similarity to lipomas on computed tomography.

Minute changes of cerebral parenchymal non-contrast computed tomography attenuation reflect cerebral volume alterations of blood

2021 ◽  
pp. 197140092199898
Author(s):  
Takamitsu Uchizawa
Keyword(s):  
Computed Tomography ◽  
Cerebral Blood Volume ◽  
Haemoglobin Concentration ◽  
Processing Method ◽  
Regional Cerebral Blood ◽  
Hounsfield Units ◽  
Computed Tomography Images ◽  
Regional Cerebral Blood Volume ◽  
Cerebral Parenchyma ◽  
Attenuation Values

Aims Non-infarcted acute cerebral ischaemic areas appear hypo-attenuated on non-contrast narrow-window computed tomography images. We aimed to determine the mechanism underlying minute computed tomography hypo-attenuation and visualise these attenuation changes on non-contrast computed tomography images. Methods The cerebral parenchyma was defined by pixels with attenuation of 20–50 Hounsfield units. We calculated the mean cerebral parenchymal attenuation in non-contrast computed tomography images. We analysed the correlation of complete blood counts with corresponding mean cerebral parenchymal attenuation values using linear regression analysis. Moreover, we developed an image processing method that involved pixel colorisation based on the noise-reduced attenuation value for minute cerebral parenchymal attenuation visualisation. Results Haemoglobin, haematocrit and red blood cell counts positively correlated with mean cerebral parenchymal attenuation values. The cerebral haematocrit is correlated with the blood haematocrit; therefore, cerebral parenchymal attenuation correlated linearly with cerebral haemoglobin concentration. Haemoglobin contents in a pixel partially determine the X-ray absorption dose and attenuation value. Pixel haemoglobin contents are determined by the cerebral volume of blood in a pixel. Image processed computed tomography images reflected cerebral volume of blood and showed the same alterations with regional cerebral blood volume maps of perfusion computed tomography. Conclusions Cerebral parenchymal attenuation correlated with cerebral haemoglobin concentration and cerebral volume of blood. Infarcted cerebral parenchyma shows about 5 Hounsfield units gray matter attenuation decrease. Attenuation decrease by less than 5 Hounsfield units means decreased cerebral volume of blood, indicating a reversible functional change. One cannot recognise minute hypo-attenuation (<5 Hounsfield units) in routine computed tomography images. However, it can be visualised through an image processing method on non-contrast computed tomography images. It may detect pre-infarction cerebral volume of blood and regional cerebral blood volume alterations.

scholarly journals Computed tomography simulator conversion curve dependence on scan parameters and phantom dimension

2020 ◽  
Author(s):  
Goran Kolarevic ◽  
Dražan Jaroš ◽  
Bojan Pavičar ◽  
Tatjana Ignjć ◽  
Aleksandar Kostovski ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Statistical Significance ◽  
Field Of View ◽  
Reference Curve ◽  
Hounsfield Units ◽  
Treatment Planning Systems ◽  
Relative Electron Density ◽  
Relative Electron ◽  
Dosimetric Study ◽  
The Difference

Introduction: Using computed tomography (CT) and treatment planning systems (TPS) in radiotherapy, due to the difference in photon beam energy on CT and linear accelerator, it is necessary to convert Hounsfield units (HU) to relative electron density (RED) values. The aim of this dosimetric study was to determine whether there is a significant effect of potential in the CT tube, field of view size (FOV), and phantom dimensions on the CT conversion curve CT-RED. The second aim is whether there are significant differences between the CT-RED obtained by the Computerized Imaging Reference Systems (CIRS) Thorax 002LFC phantom and the “reference” curve in the TPS, obtained by the CIRS 062M pelvis phantom, at the same CT conditions.Methods: Heterogeneous CIRS 062M and CIRS Thorax 002LFC phantoms were used, which anatomically and dimensionally represent the human pelvis, head, and thorax, with a set of known RED inserts. They were scanned on a CT LightSpeed GE simulator and obtained CT-RED.Results: The high voltage in the CT tube had a significant effect on the HU (t = 10.72, p < 0.001) for RED values >1.1, while FOV as a parameter did not show statistical significance for the 062M pelvis phantom. Comparing the slopes (062M pelvis and head) of the CT-RED for RED ≥ 1.1, the obtained value is t = 1.404 (p = 0.163). In the case of a 062M pelvis and a 002LFC phantom, we have seen a difference in RED values (for the same HU value) of 5 % in the RED region ≥ 1.1 (bone).Conclusion: Patients should be imaged on a CT simulator only at the potential of the CT tube on which the conversion curve was recorded. The influence of the FOV and scanned phantom dimensions is not statistically significant on the appearance of the calibration curve (RED ≥ 1.1).

scholarly journals Intelligent Algorithm-Based Computed Tomography Image Features in Diagnosis of the Effect of Radiofrequency Ablation in Liver Cancer

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yufeng Cha ◽  
Zhili Wei ◽  
Chi Ma ◽  
Lei Zhang
Keyword(s):  
Computed Tomography ◽  
Radiofrequency Ablation ◽  
Ct Images ◽  
Segmentation Algorithm ◽  
Control Group ◽  
Observation Group ◽  
Ct Image ◽  
Comprehensive Diagnosis ◽  
Kappa Value ◽  
The Difference

To provide a reference for finding a reasonable evaluation method for treatment effect of radiofrequency ablation (RFA), computed tomography (CT) image optimized by the intelligent segmentation algorithm was utilized to evaluate the liver condition of hepatocellular carcinoma (HCC) patients after RFA and to estimate the patient’s prognosis. Eighty-eight patients with HCC who needed RFA surgery after diagnosis in our hospital were selected. The CT images before optimization were set as the control group; the CT images after optimization were set as the observation group. Comprehensive diagnosis was taken as the gold standard to compare the ablation range and residual lesions under CT scans before and after surgery. The results showed that the consistency of the two sets of CT images was compared with comprehensive diagnosis under different diameters of the lesion. The difference between the two groups was not statistically considerable when the diameter of the lesion was less than 50 mm ( P > 0.05 ). For lesions larger than 50 mm in diameter, the consistency of the observation group (83%) was remarkably higher than that of the control group (40%), and the difference was substantial ( P < 0.05 ). The kappa value of the observation group was 0.84 and that of the control group was 0.78. The kappa value of observation group was better than the control group, with considerable difference ( P < 0.05 ). In conclusion, the diagnostic effect of CT image based on intelligent segmentation algorithm was superior to conventional diagnosis when the diameter of the lesion was larger than 50 mm. Moreover, the overall improvement rate of patients after RFA treatment was far greater than the recurrence rate, indicating that the clinical adoption of RFA was very meaningful.

Attenuation of skeletal muscle and strength in the elderly: The Health ABC Study

2001 ◽  
Vol 90 (6) ◽  
pp. 2157-2165 ◽  
Author(s):  
Bret H. Goodpaster ◽  
Catherine L. Carlson ◽  
Marjolein Visser ◽  
David E. Kelley ◽  
Ann Scherzinger ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Skeletal Muscle ◽  
Muscle Strength ◽  
Attenuation Coefficient ◽  
Specific Force ◽  
Hounsfield Units ◽  
Cross Sectional ◽  
Men And Women ◽  
Muscle Attenuation ◽  
Attenuation Values

Although loss of muscle mass is considered a cause of diminished muscle strength with aging, little is known regarding whether composition of aging muscle affects strength. The skeletal muscle attenuation coefficient, as determined by computed tomography, is a noninvasive measure of muscle density, and lower values reflect increased muscle lipid content. This investigation examined the hypothesis that lower values for muscle attenuation are associated with lower voluntary isokinetic knee extensor strength at 60°/s in 2,627 men and women aged 70–79 yr participating in baseline studies of the Health ABC Study, a longitudinal study of health, aging, and body composition. Strength was higher in men than in women (132.3 ± 34.5 vs. 81.4 ± 22.0 N · m, P < 0.01). Men had greater muscle attenuation values (37.3 ± 6.5 vs. 34.7 ± 7.0 Hounsfield units) and muscle cross-sectional area (CSA) at the midthigh than women (132.7 ± 22.4 vs. 93.3 ± 17.5 cm2, P < 0.01 for both). The strength per muscle CSA (specific force) was also higher in men (1.00 ± 0.21 vs. 0.88 ± 0.21 N · m · cm−2). The attenuation coefficient was significantly lower for hamstrings than for quadriceps (28.7 ± 8.7 vs. 41.1 ± 6.9 Hounsfield units, P < 0.01). Midthigh muscle attenuation values were lowest ( P < 0.01) in the eldest men and women and were negatively associated with total body fat ( r = −0.53, P < 0.01). Higher muscle attenuation values were also associated with greater specific force production ( r = 0.26, P < 0.01). Multivariate regression analysis revealed that the attenuation coefficient of muscle was independently associated with muscle strength after adjustment for muscle CSA and midthigh adipose tissue in men and women. These results demonstrate that the attenuation values of muscle on computed tomography in older persons can account for differences in muscle strength not attributed to muscle quantity.

Diagnosis of cerebral hemorrhage before the era of computed tomography

2013 ◽  
Vol 154 (44) ◽  
pp. 1743-1746
Author(s):  
Gergely Hofgárt ◽  
Rita Szepesi ◽  
Bertalan Vámosi ◽  
László Csiba
Keyword(s):  
Computed Tomography ◽  
Cerebrospinal Fluid ◽  
Positive Predictive Value ◽  
Predictive Value ◽  
Hemorrhagic Stroke ◽  
Cranial Computed Tomography ◽  
Cerebral Stroke ◽  
Daily Routine ◽  
Stroke Patients ◽  
The Difference

Introduction: During the past decades there has been a great progress in neuroimaging methods. Cranial computed tomography is part of the daily routine now and its use allows a fast diagnosis of parenchymal hemorrhage. However, before the availability of computed tomography the differentiation between ischemic and hemorrhagic stroke was based on patient history, physical examination, percutan angiography and cerebrospinal fluid sampling, and the clinical utility could be evaluated by autopsy of deceased patients. Aim: The authors explored the diagnostic performance of cerebrospinal fluid examination for the diagnosis of ischemic and hemorrhagic stroke. Method: Data of 200 deceased stroke patients were retrospectively evaluated. All patients had liquor sampling at admission and all of them had brain autopsy. Results: Bloody or yellowish cerebrospinal fluid at admission had a positive predictive value of 87.5% for hemorrhagic stroke confirmed by autopsy, while clear cerebrospinal fluid had positive predictive value of 90.7% for ischemic stroke. Patients who had clear liquor, but autopsy revealed hemorrhagic stroke had higher protein level in the cerebrospinal fluid, but the difference was not statistically significant (p = 0.09). Conclusions: The results confirm the importance of pathological evaluation of the brain in cases deceased from cerebral stroke. With this article the authors wanted to salute for those who contributed to the development of the Hungarian neuropathology. In this year we remember the 110th anniversary of the birth, and the 60th anniversary of the death of professor Kálmán Sántha. Professor László Molnár would be 90 years old in 2013. Orv. Hetil., 154 (44), 1743–1746.

Theory-Practice Gap: The Experiences of Nigerian Nursing Students

2018 ◽  
Vol 20 (1) ◽  
Author(s):  
Titilayo Dorothy Odetola ◽  
Olusola Oluwasola ◽  
Christoph Pimmer ◽  
Oluwafemi Dipeolu ◽  
Samson Oluwayemi Akande ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Nursing Students ◽  
Developing Country ◽  
The Body ◽  
Clinical Staff ◽  
Clinical Settings ◽  
Practice Gap ◽  
The Difference ◽  
Analyse Data ◽  
Theory Practice Gap

The “disconnect” between the body of knowledge acquired in classroom settings and the application of this knowledge in clinical practice is one of the main reasons for professional fear, anxiety and feelings of incompetence among freshly graduated nurses. While the phenomenon of the theory-to-practice gap has been researched quite extensively in high-income country settings much less is known about nursing students’ experiences in a developing country context. To rectify this shortcoming, the qualitative study investigated the experiences of nursing students in their attempt to apply what they learn in classrooms in clinical learning contexts in seven sites in Nigeria. Thematic content analysis was used to analyse data gained from eight focus group discussions (n = 80) with the students. The findings reveal a multifaceted theory-practice gap which plays out along four tensions: (1) procedural, i.e. the difference between practices from education institutions and the ones enacted in clinical wards – and contradictions that emerge even within one clinical setting; (2) political, i.e. conflicts that arise between students and clinical staff, especially personnel with a lower qualification profile than the degree that students pursue; (3) material, i.e. the disconnect between contemporary instruments and equipment available in schools and the lack thereof in clinical settings; and (4) temporal, i.e. restricted opportunities for supervised practice owing to time constraints in clinical settings in which education tends to be undervalued. Many of these aspects are linked to and aggravated by infrastructural limitations, which are typical for the setting of a developing country. Nursing students need to be prepared regarding how to deal with the identified procedural, political, material and temporal tensions before and while being immersed in clinical practice, and, in so doing, they need to be supported by educationally better qualified clinical staff.

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