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OBJECTIVES: The aim of this study was to emphasize the necessity of a standard in segmentation threshold and algorithm for measuring volume and surface area of mastoid air cell system (MACS). METHODS: First, we obtained axial computed tomography scans of 54 normal temporal bones from 27 subjects. Then, we manipulated Hounsfield units (HU) image data in DICOM (digital imaging and communications in medicine) files directly using our program. The volume and surface area of MACS were computed and compared at segmentation thresholds (HU) from -700 to 0 at intervals of 50 using 2 algorithms; square pixel based (SP) algorithm and marching square (MS) algorithm. RESULTS: No significant difference was found between the volumes computed by SP and MS algorithms at each segmentation threshold. The surface area computed by SP algorithm, however, was significantly larger than that by MS algorithm. We could minimize this significant difference through a modification of the SP algorithm. As the lower HU threshold value was set, the smaller volume was measured. The surface area showed a plateau at a threshold of approximately -200 HU. The segmentation threshold had greater influence on the measured volume of MACS than the algorithm did. CONCLUSION: A standard method for measuring volume and surface area of MACS is thought to be necessary. We suggest that the MS algorithm and -200 HU of the threshold could be a standard in the measurement of volume and surface area of MACS.
Subject(s)
Mastoid , Organ Size , Temporal BoneABSTRACT
A angiotomografia computadorizada de coronárias (angioTC de coronárias) é um excelente método de imagem não invasivo para avaliar a doença arterial coronariana. Atualmente, a dose de radiação efetiva estimada da angioTC de coronárias pode ser reduzida em tomógrafos de última geração com múltiplos detectores, como o tomógrafo com 320 fileiras de detectores (320-CT), sem prejuízo na acurácia diagnóstica da angioTC de coronárias. Para reduzir ainda mais a dose de radiação, novos algoritmos de reconstrução iterativa foram recentemente introduzidos por vários fabricantes de tomógrafos, que atualmente são utilizados rotineiramente nesse exame. Neste trabalho, apresentamos nossa experiência inicial na angioTC de coronárias utilizando o 320-CT e o Adaptive Iterative Dose Reduction 3D (AIDR-3D). Apresentamos ainda as indicações mais comuns desse exame na rotina da instituição bem como os protocolos de aquisição da, angioTC de coronárias com as atualizações relacionadas a essa nova técnica para reduzir a dose de radiação. Concluímos que a dose de radiação da angioTC de coronárias pode ser reduzida seguindo o princípio as low as reasonable achievable (tão baixo quanto razoavelmente exequível), combinando a indicação de exame com técnicas bem documentadas para a diminuição da dose de radiação, como o uso de betabloqueadores e a redução do kV, com os mais recentes aplicativos de reconstrução iterativa para redução da dose de radiação, como o AIDR-3D.
Coronary computed tomography angiography (coronary CTA) is a powerful non-invasive imaging method to evaluate coronary artery disease. Nowadays, coronary CTA estimated effective radiation dose can be dramatically reduced using state-of-the-art scanners, such as 320-row detector CT (320-CT), without changing coronary CTA diagnostic accuracy. To optimize and further reduce the radiation dose, new iterative reconstruction algorithms were released recently by several CT manufacturers, and now they are used routinely in coronary CTA. This paper presents our first experience using coronary CTA with 320-CT and the Adaptive Iterative Dose Reduction 3D (AIDR-3D). In addition, we describe the current indications for coronary CTA in our practice as well as the acquisition standard protocols and protocols related to CT application for radiation dose reduction. In conclusion, coronary CTA radiation dose can be dramatically reduced following the "as low as reasonable achievable" principle by combination of exam indication and well-documented technics for radiation dose reduction, such as beta blockers, low-kV, and also the newest iterative dose reduction software as AIDR-3D.
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Coronary Angiography , Coronary Artery Disease , Diagnostic Imaging , Image Processing, Computer-Assisted , Myocardial Ischemia , Radiation Exposure Control , Radiation, IonizingABSTRACT
PURPOSE: This study was performed to evaluate possible variations in maxillary and mandibular bone texture of normal population using the fractal analysis, particles count, and area fraction in intraoral radiographs. MATERIALS AND METHODS: Periapical radiographs of patients who had full mouth intraoral radiographs were collected. Regions of interest (100x100 pixels) were located between the teeth of the maxillary anterior, premolar, and molar area, as well as the mandibular anterior, premolar, and molar areas. The fractal dimension (FD) was calculated by using the box counting method. The particle count (PC) and area fraction (AF) analyses were also performed. RESULTS: There was no significant difference in the FD values among the different groups of age, gender, upper, and lower jaws. The mean FD value was 1.49+/-0.01. The mean PC ranged from 44 to 54, and the mean AF ranged from 10.92 to 11.85. The values of FD, PC, and AF were significantly correlated with each other except for the upper molar area. CONCLUSION: According to the results, patients with normal trabecular pattern showed a FD of approximately 1.5. Based on these results, further investigation would be recommended if the FD value of patient significantly differenct from this number, since the alteration of this value indicates microstructural modification of trabecular pattern of the jaws. Additionally, with periapical radiographs, simple and cost-effective, PC and AF could be used to assess the deviation from the normal.
Subject(s)
Humans , Bicuspid , Fractals , Jaw , Molar , Mouth , ToothABSTRACT
Objective To determine the accuracy and radiation dose of dual-energy computed tomography (CT) in evaluating solitary pulmonary nodules (SPNs) by virtual non-enhanced images.MethodsSixty-one patients with SPNs including 39 malignant and 18 benign nodules proved by pathology underwent DECT scans. The CT values of SPNs on enhanced weighted average and virtual non-enhanced images were compared by using Liver VNC processing unit in terms of their diagnostic accuracy for distinguishing malignant and benign nodules with a 20 HU threshold. Diagnostic accuracy was compared. In 28 patients of all patients, image noise and quality score of the non-enhanced and virtual non-enhanced images were compared, and radiation doses of each patient were recorded. The paired t test was used to analyze the noise difference between the plain scan and virtual non-enhanced scan. The Mann-Whitney U test was used to analyze statistically significant differences of the image quality score and radiation dose between the non-enhanced scan and virtual non-enhanced scan. ResultsThe sensitivity, specificity and accuracy for distinguishing benign and malignant nodules by using the virtual non-enhanced image of were 89. 7％(35/39), 72.2％ (13/18), 84.2％ (48/57)respectively.The noise of common CT and virtual nonenhanced images were(8. 49 ± 1. 94) HU and( 10. 14 ± 2. 18 ) HU, and there were statistically difference (t＝9.45,P＜0. 01 ). The quality scores of common CT and virtual non-enhanced images were (4.71 ±0. 46 ) and ( 4.42 ± 0. 57 ), and there were no statistical difference ( U ＝ 290. 00, P ＞ 0. 05 ). The radiation doses of common CT and DECT were ( 3. 72 ± 0. 48 ) mSv and ( 3.78 ± 0. 45 ) mSv, and there were no statistical difference ( U ＝ 350. 50,P ＞ 0. 05 ). ConclusionDECT by using virtual non-enhanced images is useful tool to distinguish the benign and malignant SPN without additional radiation dose.
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Objective To evaluate the clinical value of 18-fluoro-deoxyglucose positron emission tomography-CT(~(18)FDG PET-CT) for recurrence and metastasis in treated esophageal carcinoma (EC). Methods A retrospective study is done on 37 previously treated EC patients who underwent PET-CT scans to detect recurrent or metastatic lesions.The diagnostic accuracy of ~(18)FDG PET-CT was assessed with the help of pathological finding as well as clinical or follow-up data.Results Fourty-six sites of recurrence were finally confirmed in 37 patients by cytology,pathology or follow-up data.The sensitivity,specificity and accuracy of PET-CT in detecting recurrence of all sites were 93.5% (43/46),76.9% (20/26) and 87.5% (63/72),respectively.Two false-positive findings were found both at the anastomosis and hilar nodes,which caused the decrease in the overall specificity,especially that locally.The analysis of standard uptake value (SUV) demonstrated that patients with recurrence or who died during follow-up had higher SU- Vs compared with the control group.Condusions ~(18)FDG PET-CT is highly effective in detecting recur- rence in previously treated EC patients despite the low specificity at local sites.The analysis of stardard up- take value(SUV) provides incremental value in prognosis for this patient cohart.
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Objective To assess the value of 18-fluoro-deoxy-glucose positron emission-CT(FDG PET-CT) in defining the length of primary esophageal cancer.Methods Thirty-two patients had underg- one esophagoscopy,esophagography and FDG PET-CT scans one week before esophagectomy.There was one tumor located in the upper thoracic esophagus,22 in the middle thoracic esophagus,and 9 in the lower tho- racic esophagus.The location and length of primary lesion of the tumor was determined by esophagoscopy, esophagography,and FDG PET-CT.The length of the abnormality seen on the CT portion of the PET-CT scan was determined separately and independently by two radiologists.All results were compared with the resected specimen.Results According to esophagography,CT and PET-CT,all lesion lengths were compared with that of the resected specimen.It was found that the tumor location determined by esophagoscopy was not in accordance with the resected specimen in 2 patients.The mean length of the primary tumor,being from short to long,were (3.8?1.4),(4.1?1.5),(4.4?1.6),(5.3?1.9) and (4.7?1.7) cm,as determined by esophagoscopy,esophagography,CT,actral length of the resected specimen and PET-CT.Compared with the resected specimen,there was obvious difference (P=0.000,0.007,0.025,0.001).Considering that there might be some kind of shrinkage in the resected specimen (about 83.59%,as reported by Ma et al), we rectified the length of resected specimen and compared with other findings again.It was found that insig- nificant difference existed between PET-CT and rectified length value of the resected specimen (P=0.082). Conclusions FDG PET-CT is effective in the length determination of primary esophageal cancer.It may he used to determine the length of esophagus to be resected for patients indicated for esophagectomy.It may also be used to ac- curately delineate the gross tumor volume for patients eligible for radiotherapy.
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Objective To study the positions and ways of displaying the panorama of the ossicles in one plane respectively by multi-direction adjusting multi-planar reformation (MPR). Methods Fifty normal middle ears were scanned by using the HRCT isotropic parameters, and multi-direction adjusting MPR was performed to find out the basic positions, the rotating central point of reformation basic line, and the anatomic structure orientated the adjusting directions. The angles between adjusting lines and reformation baselines were measured. The axial, coronal, sagittal and multi-adjusting MPR images were graded according to the display of the ossicles. Then Ridit analyses and X2 test were performed. Results The demonstrating ratios of the panoramas of the malleus, incus, and stapes in one plane in multi-adjusting MPR images were 100% (50 middle ear) . The ratios were higher than those of axial (6 stapes, 0 malleus, 0 incus) , coronal (3 malleus, 0 incus, 0 stapes) , and sagittal images (0 malleus, 0 incus, 0 stapes) (Ridit analysis, P
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Objective To evaluate the clinical value of 18floro-deoxyglucose positron emission tomography-CY(~(18)FDG PET-CT)in the diagnosis of lymph node metastasis from advanced esophageal carcinoma. Methods A prospective study is perfonued here to assess whether ~(18)FDG PET-CT can improve the diagnostic accuracy in lymph node metastasis for patients with advanced esophageal carcinoma.Thirty patients had undergone esophagectomy with extensive lymph node dissection.PET-CT findings were compared with that d CT with pathological finding as the final say.Results All patients were operated successfully without peri-operative complications.The pathological examination conformed metastasis in 22 patients and 49 out of 243 excised lymph nodes.In CT analysis,the sensitivity was 40.8%,specificity was 96.9%,with a diagnostic accuracy of 85.6%, The positive and negative predictive value was 76.9%,86.4% respectively;PET-CT resulted in a sensitivity of 93.9%,specificity of 91.2%,accuracy of 91.8%.The positive predictive value was 73.0% and negative predictive value was 98.3%,The difference of sensitivity(P＜0.001),accuracy(P＜0.05)and negative predictive value between the two radiological modalities was statistically significant(P＜0.001).Conclusions With a high sensitivity and accuracy in the diagnosis of lymph node metastasis,PET-CT appears necessary in preoperative examination for advanced esophageal carcinoma in the hope that surgical treatment be guided by the results of PET-CT,especially for the elder patients with poor pulmonary function or heart or brain complications. Moreover,it could be used as the basis of the conformal radiation therapy planning for inoperable patients.