BACKGROUND Cervical spine fracture-dislocations in patients with ankylosing spondylitis(AS)are mostly unstable and require surgery.However,osteoporosis,one of the comorbidities for AS,could lead to detrimental prognos...BACKGROUND Cervical spine fracture-dislocations in patients with ankylosing spondylitis(AS)are mostly unstable and require surgery.However,osteoporosis,one of the comorbidities for AS,could lead to detrimental prognoses.There are few accurate assessments of bone mineral density in AS patients.AIM To analyze Hounsfield units(HUs)for assessing bone mineral density in AS patients with cervical fracture-dislocation.METHODS The HUs from C2 to C7 of 51 patients obtained from computed tomography(CT)scans and three-dimensional reconstruction of the cervical spine were independently assessed by two trained spinal surgeons and statistically analyzed.Inter-reader reliability and agreement were assessed by interclass correlation coefficient.RESULTS The HUs decreased gradually from C2 to C7.The mean values of the left and right levels were significantly higher than those in the middle.Among the 51 patients,25 patients(49.02%)may be diagnosed with osteoporosis,and 16 patients(31.37%)may be diagnosed with osteopenia.CONCLUSION The HUs obtained by cervical spine CT are feasible for assessing bone mineral density with excellent agreement in AS patients with cervical fracture-dislocation.展开更多
Current minimally invasive interventions for ureteric stones involve either ESWL or Ureteroscopy and stone localization is mandatory for successful treatment in both. Objectives: To avoid doing KUB radiograph before E...Current minimally invasive interventions for ureteric stones involve either ESWL or Ureteroscopy and stone localization is mandatory for successful treatment in both. Objectives: To avoid doing KUB radiograph before ESWL routinely by correlating the stone attenuation value on CT KUB with stone visualization at fluoroscopy. Methods: This is a prospective cross sectional hospital based, Multicentric study carried out on 1010 patients with ureteric stones in Sudan from August 2014 to March 2016. Results: Mean stone density in HU was 704.45 ± 300 (SD) ranging (81 - 1873) HU. All of the stones were localized using fluoroscopy and only 26.5% of them were not seen under fluoroscopy. I.V contrast was used mostly, and also mainly in the upper ureter. More than 80% of the application of contrast through the ureteric catheter was in the lower ureteric stones. 91.2% of patients with stone density ≤ 400 HU failed to appear at fluoroscopy and therefore 400 HU attenuation value can be used as a cut-off level to request doing KUB before ESWL and Ureteroscopy. Conclusion: the ureteric stones with density ≤400 HU the likelihood of being non-visualized at fluoroscopy is 91.2% therefore if the stone has ≤400 HU at CT KUB it is mandatory to do KUB before treatment above that it is most likely to be seen at fluoroscopy and no need to request KUB for them before ESWL or URS. 1) Inclusion Criteria: All patients diagnosed by CT scan to have ureteric stones for ESWL or Ureteroscopy. 2) Exclusion Criteria: Patients for whom treatment of ureteric stone by ESWL or ureteroscopy is not indicated like severe infection or poor kidney function where nephrectomy is needed.展开更多
Cone-beam CT (CBCT) images acquired during radiation treatment can be used to recalculate the dose distribution as well as to confirm the treatment location. However, it is difficult to obtain the electron densities (...Cone-beam CT (CBCT) images acquired during radiation treatment can be used to recalculate the dose distribution as well as to confirm the treatment location. However, it is difficult to obtain the electron densities (EDs) necessary for dose calculation from CBCT images because of the effects of scatter contamination during CBCT image acquisition. This paper presents a mathematical method for converting the pixel values of CBCT images (CBCT values) into Hounsfield units (HUs) of radiation treatment simulation CT (simCT) images for use in radiation treatment planning. CBCT values are converted into HUs by matching the histograms of the CBCT values with the histograms of the HUs for each slice via linear scaling of the CBCT values. For prostate cancer and head-and-neck cancer patients, the EDs obtained from converted CBCT values (mCBCT values) show good agreement with the EDs obtained from HUs, within approximately 3.0%, and the dose calculated on the basis of CBCT images shows good agreement with the dose calculated on the basis of the simCT images, within approximately 2.0%. Because the CBCT values are converted for each slice, this conversion method can account for variation in the CBCT values associated with differences in body size, body shape, and inner tissue structures, as well as in longitudinally displaced positions from the isocenter, unlike conventional methods that use electron density phantoms. This method improves on conventional CBCT-ED conversion and shows considerable potential for improving the accuracy of radiation treatment planning using CBCT images.展开更多
Objective To investigate the diagnostic and predictive value of enhanced CT Hounsfield unit value for central lymph node metastasis(CLNM)in patients with Hashimoto’s thyroiditis(HT)complicated with papillary thyroid ...Objective To investigate the diagnostic and predictive value of enhanced CT Hounsfield unit value for central lymph node metastasis(CLNM)in patients with Hashimoto’s thyroiditis(HT)complicated with papillary thyroid carcinoma(PTC).Methods The CT images of HTs with PTC confirmed by operation and pathology from 88 patients were analyzed retrospectively.Among them,50 cases of CLNM were all negative and 38 cases of CLNM were all positive.One lymph node was selected as the study subject in each case.The average HU values(AHUVs)and maximum HU values(MHUVs)were measured on the enhanced CT.The diagnostic efficacy of the two parameters for diagnosing CLNM was analyzed by the receiver operating specificity curve(ROC),and the best cut-off values were obtained,which were used to predict 103 HT with PTC CLNM in the validation group.Results The AHUVs of negative group and positive group were(63.79±15.34)HU and(90.92±18.04)HU(t=8.828,P<0.001).The MHUVs of negative group and positive group were(77.08±15.30)HU and(108.79±18.37)HU,respectively(t=7.615,P<0.001).The AUCs for AHUVs and MHUVs for the diagnosis of CLNM-positive was 0.870 and 0.906,and the cut-off values were 84.0 HU and 96.5 HU,respectively.The sensitivity,specificity,and accuracy of predicting CLNM positivity in the validation group using AHUVs≥84.0 HU were 35.7%,95.1%,and 70.9%,respectively,and MHUVs≥96.5 HU were 38.1%,93.4%,and 70.9%,respectively.Conclusion AHUVs≥84.0 HU and MHUVs≥96.5 HU have high specificity for the diagnosis of HT with PTC CLNM,which can provide an important basis for clinical treatment decision.展开更多
Computer Automated Tomography has been shown to be a valuable tool in production research because it provides a non-destructive method to identify and evaluate the internal structural characteristics of reservoir rock...Computer Automated Tomography has been shown to be a valuable tool in production research because it provides a non-destructive method to identify and evaluate the internal structural characteristics of reservoir rock. In CT scan, Hounsfield Unit (HU) is proportional to the degree of X-ray attenuation by the tissue. The aim of the present study was to introduce the method to estimate porosity which is one of physical parameters of reservoir rock though HU data. In this study, an Image J software was used to extract Hounsfield Unit data and calibrate by standard material’s density. This method provides the ability of using CT Scanner in advanced reservoir characterization and flow test experiments.展开更多
目的研究胸腰椎骨折患者DEXA(dual-energy X-ray absorptiometry,DEXA)所测BMD(bone mineral density,BMD)、T值(T-score)、腰椎HU值(hounsfield unit,HU)和改良VBQ(vertebral body quality,VBQ)评分的差异,并分析四者间的相关性以及BMD...目的研究胸腰椎骨折患者DEXA(dual-energy X-ray absorptiometry,DEXA)所测BMD(bone mineral density,BMD)、T值(T-score)、腰椎HU值(hounsfield unit,HU)和改良VBQ(vertebral body quality,VBQ)评分的差异,并分析四者间的相关性以及BMD、T值、腰椎HU值和改良VBQ评分在预测胸腰椎骨折的效能特点。方法收集2022年1月至2025年3月在昆明医科大学第二附属医院骨科行住院治疗的胸腰椎脆性骨折患者。将符合纳入标准的132例患者分为骨折组(n=63)与非骨折组(n=69),并分别在DEXA上记录L1~L4椎体BMD、T值,腰椎CT测量HU值,腰椎MRI(magnetic resonance imaging,MRI)测量计算VBQ评分。组间比较采用独立样本t检验,BMD、T值、HU值、改良VBQ评分四者之间的相关性采用Pearson's相关性检验,并用受试者工作曲线(receiver-operator curve,ROC)分析其预测胸腰椎骨折的效能。结果骨折组患者中L1~L4的平均BMD、T值、HU值均低于非骨折组,而改良VBQ评分高于非骨折组,两组之间均存在显著差异(P<0.001)。相关性分析中,L1~L4的BMD、T值与L1~L4 HU值呈显著正相关(P<0.001),L1~L4的BMD、T值、L1~L4HU值三者与改良VBQ评分之间呈显著负相关(P<0.001)。L1~L4平均T值、BMD、HU值和改良VBQ评分预测胸腰椎骨折的AUC值分别为0.826、0.836、0.759、0.875,其分别对应最佳阈值为T值(-1.65)、BMD(0.836)、HU值(68.4)、改良VBQ评分(3.01)。结论L1~L4椎体BMD、T值、HU值和改良VBQ评分四者之间相关性显著,都可以作为预测胸腰椎骨折效能的指标,其中改良VBQ评分预测表现最好,是良好的椎体骨质量评估辅助手段。展开更多
BACKGROUND Thread rhinoplasty can trigger a reaction to thread material,which is a foreign body.We compared clinical features induced by absorbable and non-absorbable threads following thread rhinoplasty.CASE SUMMARY ...BACKGROUND Thread rhinoplasty can trigger a reaction to thread material,which is a foreign body.We compared clinical features induced by absorbable and non-absorbable threads following thread rhinoplasty.CASE SUMMARY Two patients who underwent different thread materials showed different clinical courses and different Hounsfield unit(HU)values in computed tomography.Patients with absorbable thread showed high HU values similar to a metallic material,and the HU value of inflammation was similar to vascular tissues with a lot of water(250).In the intraoperative field,absorbable thread materials and micro-abscesses were observed.In contrast,in the case of a non-absorbable thread,an object presumed to be thread was seen on the computed tomography(CT),and the HU value of inflammatory tissues was less than 100.In both patients,post-operative HU decreased to less than 100 and the clinical course improved.In both cases,histopathologic findings revealed foreign body granuloma associated with inflammation.CONCLUSION Absorbable threads were more aggressive and are more easily detected on CT.展开更多
文摘BACKGROUND Cervical spine fracture-dislocations in patients with ankylosing spondylitis(AS)are mostly unstable and require surgery.However,osteoporosis,one of the comorbidities for AS,could lead to detrimental prognoses.There are few accurate assessments of bone mineral density in AS patients.AIM To analyze Hounsfield units(HUs)for assessing bone mineral density in AS patients with cervical fracture-dislocation.METHODS The HUs from C2 to C7 of 51 patients obtained from computed tomography(CT)scans and three-dimensional reconstruction of the cervical spine were independently assessed by two trained spinal surgeons and statistically analyzed.Inter-reader reliability and agreement were assessed by interclass correlation coefficient.RESULTS The HUs decreased gradually from C2 to C7.The mean values of the left and right levels were significantly higher than those in the middle.Among the 51 patients,25 patients(49.02%)may be diagnosed with osteoporosis,and 16 patients(31.37%)may be diagnosed with osteopenia.CONCLUSION The HUs obtained by cervical spine CT are feasible for assessing bone mineral density with excellent agreement in AS patients with cervical fracture-dislocation.
文摘Current minimally invasive interventions for ureteric stones involve either ESWL or Ureteroscopy and stone localization is mandatory for successful treatment in both. Objectives: To avoid doing KUB radiograph before ESWL routinely by correlating the stone attenuation value on CT KUB with stone visualization at fluoroscopy. Methods: This is a prospective cross sectional hospital based, Multicentric study carried out on 1010 patients with ureteric stones in Sudan from August 2014 to March 2016. Results: Mean stone density in HU was 704.45 ± 300 (SD) ranging (81 - 1873) HU. All of the stones were localized using fluoroscopy and only 26.5% of them were not seen under fluoroscopy. I.V contrast was used mostly, and also mainly in the upper ureter. More than 80% of the application of contrast through the ureteric catheter was in the lower ureteric stones. 91.2% of patients with stone density ≤ 400 HU failed to appear at fluoroscopy and therefore 400 HU attenuation value can be used as a cut-off level to request doing KUB before ESWL and Ureteroscopy. Conclusion: the ureteric stones with density ≤400 HU the likelihood of being non-visualized at fluoroscopy is 91.2% therefore if the stone has ≤400 HU at CT KUB it is mandatory to do KUB before treatment above that it is most likely to be seen at fluoroscopy and no need to request KUB for them before ESWL or URS. 1) Inclusion Criteria: All patients diagnosed by CT scan to have ureteric stones for ESWL or Ureteroscopy. 2) Exclusion Criteria: Patients for whom treatment of ureteric stone by ESWL or ureteroscopy is not indicated like severe infection or poor kidney function where nephrectomy is needed.
文摘Cone-beam CT (CBCT) images acquired during radiation treatment can be used to recalculate the dose distribution as well as to confirm the treatment location. However, it is difficult to obtain the electron densities (EDs) necessary for dose calculation from CBCT images because of the effects of scatter contamination during CBCT image acquisition. This paper presents a mathematical method for converting the pixel values of CBCT images (CBCT values) into Hounsfield units (HUs) of radiation treatment simulation CT (simCT) images for use in radiation treatment planning. CBCT values are converted into HUs by matching the histograms of the CBCT values with the histograms of the HUs for each slice via linear scaling of the CBCT values. For prostate cancer and head-and-neck cancer patients, the EDs obtained from converted CBCT values (mCBCT values) show good agreement with the EDs obtained from HUs, within approximately 3.0%, and the dose calculated on the basis of CBCT images shows good agreement with the dose calculated on the basis of the simCT images, within approximately 2.0%. Because the CBCT values are converted for each slice, this conversion method can account for variation in the CBCT values associated with differences in body size, body shape, and inner tissue structures, as well as in longitudinally displaced positions from the isocenter, unlike conventional methods that use electron density phantoms. This method improves on conventional CBCT-ED conversion and shows considerable potential for improving the accuracy of radiation treatment planning using CBCT images.
基金Zhejiang Provincial Medical and Health Technology Project(2020RC091,2021RC024)。
文摘Objective To investigate the diagnostic and predictive value of enhanced CT Hounsfield unit value for central lymph node metastasis(CLNM)in patients with Hashimoto’s thyroiditis(HT)complicated with papillary thyroid carcinoma(PTC).Methods The CT images of HTs with PTC confirmed by operation and pathology from 88 patients were analyzed retrospectively.Among them,50 cases of CLNM were all negative and 38 cases of CLNM were all positive.One lymph node was selected as the study subject in each case.The average HU values(AHUVs)and maximum HU values(MHUVs)were measured on the enhanced CT.The diagnostic efficacy of the two parameters for diagnosing CLNM was analyzed by the receiver operating specificity curve(ROC),and the best cut-off values were obtained,which were used to predict 103 HT with PTC CLNM in the validation group.Results The AHUVs of negative group and positive group were(63.79±15.34)HU and(90.92±18.04)HU(t=8.828,P<0.001).The MHUVs of negative group and positive group were(77.08±15.30)HU and(108.79±18.37)HU,respectively(t=7.615,P<0.001).The AUCs for AHUVs and MHUVs for the diagnosis of CLNM-positive was 0.870 and 0.906,and the cut-off values were 84.0 HU and 96.5 HU,respectively.The sensitivity,specificity,and accuracy of predicting CLNM positivity in the validation group using AHUVs≥84.0 HU were 35.7%,95.1%,and 70.9%,respectively,and MHUVs≥96.5 HU were 38.1%,93.4%,and 70.9%,respectively.Conclusion AHUVs≥84.0 HU and MHUVs≥96.5 HU have high specificity for the diagnosis of HT with PTC CLNM,which can provide an important basis for clinical treatment decision.
文摘Computer Automated Tomography has been shown to be a valuable tool in production research because it provides a non-destructive method to identify and evaluate the internal structural characteristics of reservoir rock. In CT scan, Hounsfield Unit (HU) is proportional to the degree of X-ray attenuation by the tissue. The aim of the present study was to introduce the method to estimate porosity which is one of physical parameters of reservoir rock though HU data. In this study, an Image J software was used to extract Hounsfield Unit data and calibrate by standard material’s density. This method provides the ability of using CT Scanner in advanced reservoir characterization and flow test experiments.
基金Supported by the National Research Foundation of Korea grant funded by the Korea government(MSIT),No.2021R1G1A1008337the Soonchunhyang University Research Fund.
文摘BACKGROUND Thread rhinoplasty can trigger a reaction to thread material,which is a foreign body.We compared clinical features induced by absorbable and non-absorbable threads following thread rhinoplasty.CASE SUMMARY Two patients who underwent different thread materials showed different clinical courses and different Hounsfield unit(HU)values in computed tomography.Patients with absorbable thread showed high HU values similar to a metallic material,and the HU value of inflammation was similar to vascular tissues with a lot of water(250).In the intraoperative field,absorbable thread materials and micro-abscesses were observed.In contrast,in the case of a non-absorbable thread,an object presumed to be thread was seen on the computed tomography(CT),and the HU value of inflammatory tissues was less than 100.In both patients,post-operative HU decreased to less than 100 and the clinical course improved.In both cases,histopathologic findings revealed foreign body granuloma associated with inflammation.CONCLUSION Absorbable threads were more aggressive and are more easily detected on CT.
