Conventional High-resolution CT Research Articles

Influence of field of view size on image quality: ultra-high-resolution CT vs. conventional high-resolution CT

ObjectivesThis study was conducted in order to compare the effect of field of view (FOV) size on image quality between ultra-high-resolution CT (U-HRCT) and conventional high-resolution CT (HRCT).MethodsEleven cadaveric lungs were scanned with U-HRCT and conventional HRCT and reconstructed with five FOVs (40, 80, 160, 240, and 320 mm). Three radiologists evaluated and scored the images. Three image evaluations were performed, comparing the image quality with the five FOVs with respect to the 160-mm FOV. The first evaluation was performed on conventional HRCT images, and the second evaluation on U-HRCT images. Images were scored on normal structure, abnormal findings, and overall image quality. The third evaluation was a comparison of the images obtained with conventional HRCT and U-HRCT, with scoring performed on overall image quality. Quantitative evaluation of noise was performed by setting ROIs.ResultsIn conventional HRCT, image quality was improved when the FOV was reduced to 160 mm. In U-HRCT, image quality, except for noise, improved when the FOV was reduced to 80 mm. In the third evaluation, overall image quality was improved in U-HRCT over conventional HRCT at all FOVs. Noise of U-HRCT increased with respect to conventional HRCT when the FOV was reduced from 160 to 40 mm. However, at 240- and 320-mm FOVs, the noise of U-HRCT and conventional HRCT showed no differences.ConclusionsIn conventional HRCT, image quality did not improve when the FOV was reduced below 160 mm. However, in U-HRCT, image quality improved even when the FOV was reduced to 80 mm.Key Points• Reducing the size of the field of view to 160 mm improves diagnostic imaging quality in high-resolution CT.• In ultra-high-resolution CT, improvements in image quality can be obtained by reducing the size of the field of view to 80 mm.• Ultra-high-resolution CT produces images of higher quality compared with conventional HRCT irrespective of the size of the field of view.

EP1.11-08 Ultra-High-Resolution CT to Project the Detailed Components in Nodules; Fat Components in Pulmonary Hamartomas

The purpose of this study was to evaluate the utility of the detailed matrix of ultra-high-resolution CT (UHRCT) to detect the detailed attenuation heterogeneity in pulmonary hamartoma which contains fat component. Seven consecutive patients (three males, four females; 48-73 y.o.) with pulmonary hamartoma who underwent UHRCT were enrolled retrospectively. Each patient’s hamartoma was diagnosed by using bronchoscope, surgical therapy or follow up study. All CT studies were performed by using ultra-high-resolution CT machine (Aquilion Precision; Canon Medical Systems, Otawara, Japan). All CT examinations were performed with 160-detector row CT scanner; 120kVp, auto-mAs, 1792 channels, collimation 0.25 mm x 160 rows, 1024 matrix. Conventional high-resolution CT (HRCT) images were reconstructed with 1mm slice, 1mm interval, 512 x 512 matrix. Ultra-high- resolution CT (UHRCT) images were reconstructed with 0.25 mm slice, 0.25 mm interval, 1024 x 1024 matrix. The CT densities of each hamartoma were measured by placing ROI at the longest diameter of the nodule on CT image. The lowest densities in the nodule were statistically compared between on HRCT and UHRCT by using paired t-test. P value less than 0.05 was considered to be significant. The average minimum densities of hamartomas on HRCT and UHRCT were -39.1 and -65.0, respectively (p = 0.092). The lowest densities of hamartomas were lower on UHRCT than on HRCT, not significantly. The UHRCT’s smaller voxel may reveal the detailed heterogeneity in the nodule to detect fat component of hamartoma.

Application of High-Resolution C-Arm CT Combined with Streak Metal Artifact Removal Technology for the Stent-Assisted Embolization of Intracranial Aneurysms.

Metal artifacts from coils and stents limit the level of detail in C-arm CT images of stent attachment and coiling attenuation in the aneurysm neck. We evaluated the utility of high-resolution C-arm CT combined with streak metal artifact removal technology for stent-assisted embolization of intracranial aneurysms. From October 2017 to July 2018, the First Affiliated Hospital of Zhengzhou University treated 107 patients with intracranial aneurysms (118 aneurysms in total) with stent-assisted embolization. Conventional C-arm CT and high-resolution C-arm CT scanning of the stented area were performed during and after treatment. 3D images were reconstructed with and without streak metal artifact removal techniques. Subsequently, the image quality was compared. The reconstructed images indicated the stent deployment degree and packing density. Follow-up assessments included clinical and angiographic outcomes and complications. In total, 118 aneurysms were successfully embolized using 118 stents. Image quality was significantly higher (P < .05) with high-resolution C-arm CT combined with streak metal artifact removal reconstruction. Streak metal artifact removal reconstruction and 2D angiography at working angles showed incomplete deployment of 6 stents and incomplete aneurysm embolization of 15 patients, which were subsequently resolved. One case of hemorrhage was noted postoperatively. Follow-up of 93 patients at 6-13 months indicated 3 cases of aneurysm recurrence. High-resolution C-arm CT combined with the streak metal artifact removal technique effectively reduced metal artifacts from stents and coils during aneurysm embolization. This method can help physicians determine the extent of stent deployment and the packing density of coils and thus potentially reduce complications and aneurysm recurrence.

High-Resolution Chest Computed Tomography Imaging of the Lungs: Impact of 1024 Matrix Reconstruction and Photon-Counting Detector Computed Tomography.

The aim of this study was to evaluate if a high-resolution photon-counting detector computed tomography (PCD-CT) system with a 1024×1024 matrix reconstruction can improve the visualization of fine structures in the lungs compared with conventional high-resolution CT (HRCT). Twenty-two adult patients referred for clinical chest HRCT (mean CTDI vol, 13.58 mGy) underwent additional dose-matched PCD-CT (mean volume CT dose index, 13.37 mGy) after written informed consent. Computed tomography images were reconstructed at a slice thickness of 1.5 mm and an image increment of 1 mm with our routine HRCT reconstruction kernels (B46 and Bv49) at 512 and 1024 matrix sizes for conventional energy-integrating detector (EID) CT scans. For PCD-CT, routine B46 kernel and an additional sharp kernel (Q65, unavailable for EID) images were reconstructed at 1024 matrix size. Two thoracic radiologists compared images from EID and PCD-CT noting the highest level bronchus clearly identified in each lobe of the right lung, and rating bronchial wall conspicuity of third- and fourth-order bronchi. Lung nodules were also compared with the B46/EID/512 images using a 5-point Likert scale. Statistical analysis was performed using a Wilcoxon signed rank test with a P < 0.05 considered significant. Compared with B46/EID/512, readers detected higher-order bronchi using B46/PCD/1024 and Q65/PCD/1024 images for every lung lobe (P < 0.0015), but in only the right middle lobe for B46/EID/1024 (P = 0.007). Readers were able to better identify bronchial walls of the third- and fourth-order bronchi better using the Q65/PCD/1024 images (mean Likert scores of 1.1 and 1.5), which was significantly higher compared with B46/EID/1024 or B46/PCD/1024 images (mean difference, 0.8; P < 0.0001). The Q65/PCD/1024 images had a mean nodule score of 1 ± 1.3 for reader 1, and -0.1 (0.9) for reader 2, with one reader having improved nodule evaluation scores for both PCD kernels (P < 0.001), and the other reader not identifying any increased advantage over B46/EID/1024 (P = 1.0). High-resolution lung PCD-CT with 1024 image matrix reconstruction increased radiologists' ability to visualize higher-order bronchi and bronchial walls without compromising nodule evaluation compared with current chest CT, creating an opportunity for radiologists to better evaluate airway pathology.

Clinical value of ultra high resolution CT in the diagnosis of pulmonary nodules

Objective To explore the clinical value of ultra high resolution CT in the diagnosis of pulmonary nodules. Methods From January 2014 to December 2016, 120 cases with small pulmonary nodules and confirmed by pathology(maximum diameter less than or equal to 2cm) in the Fifth People's Hospital of Datong were included in the study.The 120 patients received high resolution CT scan(512×512 matrix), ultra high resolution CT scan(1 024×1 024 matrix). The images of two kinds of resolution CT were observed and analyzed, compared with high-resolution CT scan, ultra high resolution CT scanning for detection of small pulmonary nodules, CT signs detection situation, qualitative diagnosis, image quality. Results Compared with the high resolution CT scan, ultra high resolution CT scan had no statistically significant differences in the detective rate of maximum diameter of 0.5~2cm small pulmonary nodules (χ2=0.695, P>0.05), but the maximum diameter of the ultra high resolution CT scan less than or equal to 0.5cm small lung nodules detected more than that of the high resolution CT scan(χ2=6.021, P 0.05). The diagnostic accordance rates of the ultra high resolution CT scan for pulmonary malignant nodules and benign nodules were 98.08%, 97.06%, respectively, which were higher than those of the high resolution CT scan(86.54%, 85.29%, χ2=4.875, 5.850, all P 0.05). Conclusion Compared with the conventional high resolution CT scan, ultra high resolution CT scan is better for small pulmonary nodules image quality, and can accurately diagnose small pulmonary nodules, with high diagnostic accuracy, especially for the maximum diameter of less than 0.5cm of small pulmonary nodules. Key words: Solitary pulmonary nodule; Tomography, X-ray computed; Diagnosis

Improved image quality and diagnostic potential using ultra-high-resolution computed tomography of the lung with small scan FOV: A prospective study.

The aim of this study was to assess whether CT imaging using an ultra-high-resolution CT (UHRCT) scan with a small scan field of view (FOV) provides higher image quality and helps to reduce the follow-up period compared with a conventional high-resolution CT (CHRCT) scan. We identified patients with at least one pulmonary nodule at our hospital from July 2015 to November 2015. CHRCT and UHRCT scans were conducted in all enrolled patients. Three experienced radiologists evaluated the image quality using a 5-point score and made diagnoses. The paired images were displayed side by side in a random manner and annotations of scan information were removed. The following parameters including image quality, diagnostic confidence of radiologists, follow-up recommendations and diagnostic accuracy were assessed. A total of 52 patients (62 nodules) were included in this study. UHRCT scan provides a better image quality regarding the margin of nodules and solid internal component compared to that of CHRCT (P < 0.05). Readers have higher diagnostic confidence based on the UHRCT images than of CHRCT images (P<0.05). The follow-up recommendations were significantly different between UHRCT and CHRCT images (P<0.05). Compared with the surgical pathological findings, UHRCT had a relative higher diagnostic accuracy than CHRCT (P > 0.05). These findings suggest that the UHRCT prototype scanner provides a better image quality of subsolid nodules compared to CHRCT and contributes significantly to reduce the patients' follow-up period.

Ultra-High-Resolution Computed Tomography of the Lung: Image Quality of a Prototype Scanner.

PurposeThe image noise and image quality of a prototype ultra-high-resolution computed tomography (U-HRCT) scanner was evaluated and compared with those of conventional high-resolution CT (C-HRCT) scanners.Materials and MethodsThis study was approved by the institutional review board. A U-HRCT scanner prototype with 0.25 mm x 4 rows and operating at 120 mAs was used. The C-HRCT images were obtained using a 0.5 mm x 16 or 0.5 mm x 64 detector-row CT scanner operating at 150 mAs. Images from both scanners were reconstructed at 0.1-mm intervals; the slice thickness was 0.25 mm for the U-HRCT scanner and 0.5 mm for the C-HRCT scanners. For both scanners, the display field of view was 80 mm. The image noise of each scanner was evaluated using a phantom. U-HRCT and C-HRCT images of 53 images selected from 37 lung nodules were then observed and graded using a 5-point score by 10 board-certified thoracic radiologists. The images were presented to the observers randomly and in a blinded manner.ResultsThe image noise for U-HRCT (100.87 ± 0.51 Hounsfield units [HU]) was greater than that for C-HRCT (40.41 ± 0.52 HU; P < .0001). The image quality of U-HRCT was graded as superior to that of C-HRCT (P < .0001) for all of the following parameters that were examined: margins of subsolid and solid nodules, edges of solid components and pulmonary vessels in subsolid nodules, air bronchograms, pleural indentations, margins of pulmonary vessels, edges of bronchi, and interlobar fissures.ConclusionDespite a larger image noise, the prototype U-HRCT scanner had a significantly better image quality than the C-HRCT scanners.

English

OBJECTIVE: This study was conducted to determine whether there is superior diagnostic accuracy for the detection and exclusion of bronchiectasis using 16-slice CT of the chest (1 mm) compared with conventional high-resolution CT (HRCT) of the chest (10 mm). MATERIALS AND METHODS: A prospective study was carried out in the department of radiology KIIMS Bangalore over a one-year period during June 2012 – July 2013 in patients who were referred for chest CT from medicine department and pulmonologist for the investigation of bronchiectasis. All scans were performed using a 16-slice CT scanner. In addition to contiguous 1 mm slices, conventional HRCT images (1.25 mm slice every 10 mm) were prepared. Both datasets were dual read. RESULTS: There were 40 patients with a median age of 59 years (range, 52– 73 years), comprising 13 males and 27 females. 7 of 40 scans had no bronchiectasis in either dataset. 29 patients had bronchiectasis diagnosed on both HRCT and 1 mm scans. Two patients had tubular bronchiectasis on the HRCT scans, which was not confirmed on the 1 mm scans. Four patients had confirmed tubular bronchiectasis on the 1 mm scans, which was not identified on HRCT scans. 24 extra lobes demonstrated bronchiectasis on the 1 mm vs. the HRCT scans; of these, half were labeled as definite bronchiectasis on the 1 mm scan. There was a 32.8% increased confidence with the 1 mm scans compared with conventional HRCT of the chest in the diagnosis of bronchiectasis (p, 0.001). In conclusion, there is improved diagnostic accuracy and confidence for diagnosis and exclusion of bronchiectasis using 16-slice chest CT (1 mm cuts) compared with conventional HRCT of the chest.

Pulmonary Hypertension Presenting With Apnea, Cyanosis, and Failure to Thrive in a Young Child

Pulmonary Hypertension Presenting With Apnea, Cyanosis, and Failure to Thrive in a Young Child

Imaging diagnosis of the lymphangioleiomyomatosis

Objective To investigate the value of imaging diagnosis of the lymphangioleiomyomatosis( LAM ). MethodsFifteen patients with LAM confirmed by pathological assessment were analyzed retrospectively for radiologic findings. They had chest radiograph, chest highresolution CT (HRCT),abdominal CT, direct lymphangiography(DLG), chest CT and abdominal CT after DLG. Results Chest radiograph findings included normal (1), increasing of lung markings (3),disseminated honeycomb or reticular pattern ( 11 ), pneumothorax ( 2 ), and pleural effusion ( 14 ). Chest conventional CT and HRCT showed typical imaging manifestation of PLAM in all cases, including sporadic or disseminated cysts in bilateral lungs. According to the grading standard of pulmonary disease made by Avila et at, there were 3 cases in grade Ⅰ , 5 cases in grade Ⅱ and 7 cases in grade Ⅲ . Fourteen of 15 patients with LAM had positive abdominal CT findings in retroperitoneum and pelvic cavity. Common abdominal CT findings included cystic lymphangioma in 9 of 14 patients, lymphangiomyoma in 13 and both coexisting in 7.One of the 14 patients also had hepatic lipoma and angiomyolipomas. One patient had renal angiomyolipomas; and one patient had hysteromyoma. All 15 cases underwent DLG, 1 cases had lymphatic obstruction in the lumbar 3 level, the remaining 14 cases had varying degrees of thoracic duct stenosis, or obstruction. Neck trunk, subclavian trunk and bronchial trunk showed lymphatic reflux. On post-DLG CT,thoracic duet outlet obstruction was not demonstrated in 3 cases, the remaining 12 cases showed thoracic outlet obstruction, consistent with the DLG findings. Conclusion HRCT is a useful diagnostic method showing characteristic findings of PLAM. MSCT can help to detect abdominal LAM. DLG and MSCT after DLG have value in displaying obstruction site of thoracic duct or lymphatic trunks and provide guidance for operative treatment. Key words: Lymphangiomyomatosis; Tomography,X-ray computed ; Lymphography

Comparison between conventional interrupted high-resolution CT and volume multidetector CT acquisition in the assessment of bronchiectasis

The aim of this study was to determine whether there is superior diagnostic accuracy for the detection and exclusion of bronchiectasis using 16-slice CT of the chest (1 mm) compared with conventional high-resolution CT (HRCT) of the chest (10 mm). A prospective study was carried out in patients who were referred for chest CT by a chest physician for the investigation of bronchiectasis over a 1-year period. All scans were performed using a 16-slice CT scanner. In addition to contiguous 1 mm slices, conventional HRCT images (1 mm slice every 10 mm) were prepared. Both datasets were dual read. There were 53 patients with a median age of 62 years (range, 51.5-71.5 years), comprising 14 males and 39 females. 10 of 53 scans had no bronchiectasis in either dataset. 36 patients had bronchiectasis diagnosed on both HRCT and 1 mm scans. Two patients had tubular bronchiectasis on the HRCT scans, which was not confirmed on the 1 mm scans. Five patients had confirmed tubular bronchiectasis on the 1 mm scans, which was not identified on HRCT scans. 40 extra lobes demonstrated bronchiectasis on the 1 mm vs the HRCT scans; of these, half were labelled as definite bronchiectasis on the 1 mm scan. There was a 32% increased confidence with the 1 mm scans compared with conventional HRCT of the chest in the diagnosis of bronchiectasis (p < 0.001). In conclusion, there is improved diagnostic accuracy and confidence for diagnosis and exclusion of bronchiectasis using 16-slice chest CT (1 mm cuts) compared with conventional HRCT of the chest.

Comparison of the image quality between volumetric and conventional high-resolution CT with 64-slice row CT

Objective To compare the image quality between volumetric high-resolution CT (VHRCT)and conventional high-resolution CT(CHRCT),and investigate the feasibility of VHRCT.Methotis Catphan 412 phantom was scanned with protocols of CHRCT and VHRCT on a set of GE Lightspeed VCE.The spatial-resolution(LP/cm),noise(standard deviation iu an ROI)and radiation dose (CTDI)were recorded for each CT scan.Difference of noise between CHRCT and VHRCT were evaluated by paired t test.In clinical study.32 patients were scanned with VHRCT and CHRCT protocols.The image quality of CHRCT and VHRCT was rated and compared.The quality difference between CHRCT and VHRCT was assessed by Wilcoxon paired signed rank sum test.Results In phantom study.the in-plane spatial-resolution of both VHRCT and CHRCT was 11 LP/cm for axial images and 12 LP/cm for coronal reformatted images.The noise of VHRCT and CHRCT was(69.18±2.77)HU and(54.62±2.12)HU respectively(t=-15.929.P＜0.01)at the same dose level.The radiation dose of VHRCT was 19.09 mGy higher than CHRCT at the same noise level.In clinical study.the quality assessment scores of VHRCT axial images and CHRCT axial images were 3.22 and 3.24 respectively.with no significant difference(Z=-0.319,P＞0.05).The qualily assessment scores of VHRCT coronal reformatted images and CHRCT coronal reformatted images were 3.05 and 1.88 respectively with significant difference(Z=-5.088.P＜0.01).Conclusion The image qualitv of VHRCT cross-sectional image is similar to that of CHRCT.Muhiplanar images with high resolution of VHRCT are recommended.The radiation dose of VHRCT remains to be optimized. Key words: Lung; Tomography,X-ray computed; Phantoms,imaging

Conventional High-Resolution CT Versus Helical High-Resolution MDCT in the Detection of Bronchiectasis

The purpose of this study was to compare conventional high-resolution CT (HRCT) with helical 16-MDCT in the detection of bronchiectasis. We retrospectively evaluated 80 patients including 61 with bronchiectasis (mean age, 64 years; range, 22-87 years) and a control group of 19 patients with normal MDCT of the chest. Two sets of images were blindly, randomly analyzed by two observers: contiguous 1-mm slices (MDCT set) and 1-mm slices every 10 mm (HRCT set) derived from the MDCT set. Images were scored independently for presence, extent, and severity of bronchiectasis, followed by a consensus interpretation. Kappa analysis assessed inter- and intraobserver agreement. MDCT was the radiologic gold standard. Of the 61 patients with bronchiectasis diagnosed with MDCT, 56 (92%) were positive for bronchiectasis on conventional HRCT. Seven patients had positive MDCT scans only, and two patients had positive HRCT scans only. Of 479 lobes, 59 were positive for bronchiectasis on MDCT and negative on HRCT, and 19 lobes were positive for bronchiectasis on HRCT and negative on MDCT (p < 0.0001). MDCT showed 25 more lobes with cylindric, 11 more lobes with varicose, and four more lobes with cystic bronchiectasis than did HRCT. Sensitivity, specificity, and positive and negative predictive values of HRCT in detecting bronchiectasis were 71%, 93%, 88%, and 81%, respectively. Interobserver agreement for presence, extent, and severity of bronchiectasis ranged from moderate to good for MDCT (kappa values, 0.64, 0.5, and 0.48, respectively) and poor to good for HRCT (kappa values, 0.65, 0.46, and 0.25, respectively). Contiguous helical 16-MDCT with 1-mm collimation is superior to HRCT at 10-mm intervals in showing the presence and extent of bronchiectasis.

Image Quality from High-Resolution CT of the Lung: Comparison of Axial Scans and of Sections Reconstructed from Volumetric Data Acquired Using MDCT

Our objective was to compare the image quality of reconstructed thin sections obtained from a 16-MDCT scanner with that of axial high-resolution CT scans of the same patient. Fifty consecutive patients referred for CT of the chest underwent 16-MDCT and, subsequently, axial high-resolution CT. The volumetric raw data from the MDCT scans were reconstructed into slices 2-mm thick using a high-spatial-frequency reconstruction algorithm. Two blinded reviewers independently rated the images from both methods for subjective image-quality criteria. The results were tested for statistical significance using Wilcoxon's signed rank test, and p values of less than 0.05 were considered significant. The effective dose for axial high-resolution CT and volumetric MDCT was calculated. Motion artifacts were significantly more common on high-resolution CT scans than on reconstructed thin-section images (p < 0.001). The two methods differed significantly in lung attenuation (p = 0.008), mainly because of the presence of ground-glass opacities. The assessment of ground-glass attenuation was superior on axial high-resolution CT. The effective doses were 3.8 mSv for MDCT and 0.9 mSv for high-resolution CT. Reconstructed high-resolution images generated from a single MDCT data acquisition are of comparable quality to images obtained using conventional axial high-resolution CT. However, contiguous MDCT is not recommended for diseases showing predominantly ground-glass patterns, because axial high-resolution CT delineates ground-glass attenuation significantly better.

Intrathecal Gadolinium-Enhanced MR Myelography Showing Multiple Dural Leakages in a Patient with Marfan Syndrome

oss of CSF or imbalance of its turnover can cause symptoms such as orthostatic headaches, nausea, and neck pain. These symptoms are frequently the result of CSF leakage from the dura and can occur spontaneously or after trauma, lumbar puncture, or neurosurgery. It has been suggested that disorders of the connective tissues predispose patients to spontaneous CSF leaks [1]. Hence, localization and identification of dural leakages are crucial for satisfactory treatment. We present the case of a patient with Marfan syndrome and multiple dural leaks. The exact site of CSF leakage was not apparent on conventional myelography or high-resolution CT myelography, but was shown using intrathecal contrast-enhanced MR myelography. Case Report A 19-year-old man with Marfan syndrome presented with severe headaches, neck pain, and nausea. These symptoms were triggered by orthostatic conditions involving an erect posture (e.g., sitting, standing, or walking). However, the symptoms resolved after lying down for several minutes. Blood analysis and neurologic examinations presented normal parameters. Intrathecal pressure was not measurable after lumbar puncture. Spontaneous intracranial hypotension (SIH) and chronic loss of CSF were assumed to be responsible for the symptoms. MR images using T1- and T2-weighted and constructive interference in steady-state 3D imaging showed dural ectasia at different levels of the lumbosacral spine and extradural fluid with CSF-like signal performance dorsally to L5 and S1, but no connection to the subarachnoid space was proven. A CT scan of the brain showed normal cisterns, no caudal displacement of the brainstem, and no evidence of low intracranial pressure. Myelography, a postmyelography high-resolution CT scan, and T2

Multidetector CT of bronchiectasis: effect of radiation dose on image quality.

The purpose of our prospective study was to assess the image quality with respect to the radiation dose incurred by multidetector CT (MDCT) in patients with suspected bronchiectasis. SUBJECTS AND METHODS. Image clusters, composed of nine images, using MDCT (120 kVp, a 2.5-mm collimation, a pitch of 6, and 2.5-mm reconstruction intervals) were obtained at each of two levels-the azygous arch and the right inferior pulmonary vein-at 170, 100, 70, 40, 20, and 10 mA. Independently, two chest radiologists assessed and compared the quality of the images obtained at the six milliamperage exposures. Image quality was graded using a 5-point scale with lung and mediastinal window settings. Radiation doses were measured at each of the six milliamperage settings while scanning the whole lung of a thoracic phantom using MDCT. The mean image quality scores at exposures of 170, 100, 70, 40, 20, 10 mA were as follows: 3.9, 3.7, 3.8, 3.2, 2.5, 1.6 at lung window settings and 4.1, 4.3, 4.0, 3.4, 2.3, 1.3 at mediastinal window settings, respectively. Images obtained at 70 mA were rated significantly better than those obtained at 40 mA or less (p < 0.01). The mean radiation dose at 170, 100, 70, 40, 20, 10 mA was 23.72, 14.39, 10.54, 5.41, 2.74, and 1.50 mGy, respectively. With a tube current setting as low as 70 mA, MDCT provides images of acceptable quality and volumetric data sets for the evaluation of bronchiectasis. The trade-off of using MDCT rather than conventional high-resolution CT is that the radiation dose is five times higher with MDCT (10.54 mGy) than with conventional high-resolution CT (2.17 mGy with parameters of 120 kVp, 170 mA, 1-mm collimation, and 10-mm intervals).

Multislice helical CT of focal and diffuse lung disease: comprehensive diagnosis with reconstruction of contiguous and high-resolution CT sections from a single thin-collimation scan.

We tested breath-held 1-mm multislice helical CT for obtaining both contiguous and high-resolution CT sections of the chest from a single set of raw data. Seventy patients with suspected focal and diffuse lung disease were allocated into two groups for comparison. The first group (n = 35) underwent multislice helical CT of the chest with 1-mm collimation and a pitch of 6. From the raw data, 5-mm contiguous and 1.25-mm high-resolution CT sections were reconstructed. The second group (n = 35) underwent conventional single-slice helical CT and high-resolution CT. High-resolution CT sections and 5-mm scans were rated for overall image quality, spatial resolution, subjective signal-to-noise ratio, diagnostic value, depiction of bronchi and parenchyma, and motion and streak artifacts. The 5-mm scans were also rated for contrast resolution and depiction of the heart and vessels. Radiation dose was calculated. We rated 5-mm multislice helical CT superior to 5-mm single-slice helical CT, having a significantly higher total score (p = 0.0001). No significant difference (p = 0.986) was found between multislice and single-slice high-resolution CT sections. Radiation dose was 5.55 mSv for multislice helical CT and 5.50 mSv for single-slice helical CT. Contiguous chest scans of superior quality and high-resolution CT sections of equal image quality compared with single-slice helical CT can be obtained using multislice helical CT. Therefore, a comprehensive diagnosis is feasible in patients with suspected focal and diffuse lung disease by obtaining a single scan.

Pulmonary Alveolar Microlithiasis: High-Resolution CT Scan

Pulmonary Alveolar Microlithiasis: High-Resolution CT Scan

Imaging of trabecular bone structure in osteoporosis.

Osteoporosis is a metabolic bone disorder that is characterized by reduced bone mass and a deterioration of bone structure which results in an increased fracture risk. Since the disease is preventable, diagnostic techniques are of major importance. Standard techniques determine bone mineral density, whereas some of the newer techniques focus on trabecular structure. This article reviews structure analysis techniques in the diagnosis of osteoporosis. Imaging techniques applied to the assessment of trabecular bone structure include conventional radiography, magnification radiography, high-resolution CT (HRCT) and high-resolution MR imaging (HRMRI). The best results were obtained using high-resolution tomographic techniques. The highest spatial resolutions in vivo were achieved using HRMRI. The most common texture analysis techniques that have been used are morphological parameters (analogous to bone histomorphometry). Fractal dimension, co-occurrence matrices, mathematical filter techniques and autocorrelation functions are more complex techniques. Most of the studies evaluating structure analysis show that texture parameters and bone mineral density both predict bone strength and osteoporotic fractures, and that combining both techniques yields the best results in the diagnosis of osteoporosis.

Lung cancer in patients with idiopathic pulmonary fibrosis: CT findings.

The frequency of lung cancer in patients with idiopathic pulmonary fibrosis (IPF) is higher than that of general population. To evaluate CT findings of lung cancer associated with IPF, we analyzed 32 patients with lung cancer associated with IPF. We analyzed retrospectively 32 patients with histologically confirmed lung cancer out of 244 consecutive cases diagnosed as IPF by either CT and clinical findings (n = 220) or histologically (n = 24). The patients were 40-85 years old (mean 66 years, M/F = 31/1). Scanning techniques were conventional CT in 24 patients, high-resolution CT (HRCT) in 2 patients, and both conventional CT and HRCT in 6 patients. We analyzed the CT patterns, locations, and histologic types of lung cancer. The frequency of lung cancer in patients with IPF was 13.1% (32/244). In 17 of 32 patients, the CT findings of lung cancer were ill defined lesions mimicking air-space consolidation. Lung cancer was located mainly in the lower lobes (21/32) and peripheral portion (21/32). Histologically, squamous cell carcinoma was the most common type (18/32). Typical CT findings of lung cancer were ill defined consolidation-like masses at the peripheral portion where the most advanced fibrosis was located.