Evaluation of pulmonary embolisms using coronal reformations on 64-row multidetector-row computed tomography: Comparison with axial images

OBJECTIVE: To evaluate coronal reformations of the chest on 64-row multidetector-row computed tomography (MDCT) for detection of pulmonary embolisms compared with axial images. METHODS: Thirty-eight consecutive patients who underwent pulmonary computed tomography angiography (CTA) on 64-row MDCT for a suspected pulmonary embolism were retrospectively studied. Contiguous 2-mm axial and coronal images were reviewed independently. A pulmonary embolism was assessed in the main, lobar, or segmental pulmonary arteries and was scored using a 5-point scale. RESULTS: A pulmonary embolism was demonstrated in 10% (4 of 38) of axial images and 16% (6 of 38) of coronal images. Interpretation was concordant in 95% to 100% of cases for a main or lobar pulmonary embolism and in 80% to 82% of cases for a segmental pulmonary embolism. Agreement of scores was almost perfect for a a main or lobar pulmonary embolism (mean weighted kappa value = 0.969) and moderate to good for a segmental pulmonary embolism (mean weighted kappa value = 0.560). CONCLUSION: Coronal reformations of the chest on 64-row MDCT were as informative as axial images for the detection of main, lobar, and segmental pulmonary embolisms.     

Coronal reformations of the chest on 64-row multi-detector row CT: evaluation of image quality in comparison with 16-, 8- and 4-row multi-detector row CT

PURPOSE: To evaluate image quality of coronal reformations of chest performed on 64-row MDCT in comparison with 16-, 8- and 4-row MDCT. MATERIALS AND METHODS: Consecutive patients who underwent pulmonary CT angiography using four different MDCT scanners were retrospectively studied with IRB approval: (1) n=30, 64-row MDCT; (2) n=30, 16-row MDCT; (3) n=30, 8-row MDCT; (4) n=30, 4-row MDCT. Coronal reformatted images (2 mm thickness and 2mm intervals for 64-row MDCT; 5 mm thickness and 5 mm intervals for 16-, 8- and 4-row MDCT) were evaluated by consensus reading of two board-certified radiologists who were blinded to scanner type. The image quality of overall chest appearance and individual thoracic structures including heart, aorta and pulmonary arteries was graded using five-point scale. Grades from four different scanners were compared using Kruskal-Wallis test. A second evaluation was performed in 48 randomly selected patients (12 patients for each scanner). Reproducibility was assessed using weighted-kappa analysis. RESULT: Significant reproducibility was observed between the first and second evaluations in 48 patients both for image quality of overall chest (weighted kappa=0.826) and each thoracic structure (mean weighted kappa=0.803; range, 0.729-0.858). Image quality of overall chest and individual thoracic structures differed significantly among four different MDCT groups, with 64-row MDCT having the highest grades, followed by 16-, 8- and 4-row MDCT (mean grades for overall chest in each scanner: 3.9, 3.0, 2.4 and 1.9, respectively) (P<0.0001 for overall chest and each thoracic structure). CONCLUSION: When comparing coronal reformations of chest using four different MDCT scanners, the 64-row MDCT had the highest image quality for overall chest appearance and individual thoracic structures, followed by 16-, 8- and finally 4-row MDCT.     

Identification of the normal appendix in healthy adults by 64-slice MDCT: the value of adding coronal reformation images

The aim of this study was to assess retrospectively the value of adding coronal reformation images to the identification of the normal appendix using 64-slice multidetector CT (MDCT). 200 consecutive healthy adults with no history of abdominal surgery underwent abdominal CT using 64-slice MDCT without oral contrast administration and were enrolled in the study. Two gastrointestinal radiologists first interpreted the axial images only; after a 2-week interval, they then interpreted both the axial and the coronal images while blinded to the first interpretation. The identification of the normal appendix was interpreted using a four-point scale: 1, not identified; 2, identified with low confidence; 3, probably identified; 4, definitely identified. Agreement between the readers was determined with the use of weighted kappa statistics. Differences in confidence ratings for identification of the appendix were determined with the Wilcoxon signed rank test. The agreement between the readers was higher when both axial and coronal images were reviewed (kappa = 0.85) than when only the axial scans images were reviewed (kappa = 0.43). The mean confidence scores for the identification of the normal appendix by the two readers were significantly higher when both the axial and coronal images were reviewed (mean, 3.81+/-0.498 and 3.83+/-0.485 for the two readers, respectively) than when only the axial images were reviewed (mean, 3.27+/-0.819 and 3.47+/-0.856, respectively) (all p<0.01). Therefore, adding coronal reformation images to 64-slice MDCT significantly improves inter-reader agreement and confidence in the identification of the normal appendix.     

Primary interpretation of thoracic MDCT images using coronal reformations

OBJECTIVE: The objective of this study was to evaluate the accuracy and efficiency of primary interpretation of thoracic MDCT using coronal reformations as compared with transverse images. SUBJECTS AND METHODS: Fifty patients (18 females, 32 males; age range, 15-93 years; mean age, 63.6 years) underwent 4-MDCT of the chest (detector width, 1 mm; beam pitch, 1.5). Contrast material was administered in 20 of the 50 patients. Coronal and transverse sections were reformatted into 5-mm-thick sections at 3.5-mm intervals. All available image and clinical data consensually reviewed by two thoracic radiologists served as the reference standard. Subsequently, three other thoracic radiologists independently evaluated reformatted coronal and transverse images at two separate review sessions. Each image set was assessed in 58 categories for abnormalities of the lungs, mediastinum, pleura, chest wall, diaphragm, abdomen, and skeleton. Interpretation times and number of images assessed were recorded. Sensitivity, specificity, and interobserver concordance were calculated. Differences in mean sensitivities and specificities were evaluated with Wilcoxon's signed rank test. RESULTS: The most common findings identified were pulmonary nodules (n = 73, transverse images; n = 72, coronal images) and emphysema (n = 45, transverse; n = 40, coronal). The mean detection sensitivity of all lesions was significantly (p = 0.001) lower on coronal (44% +/- 26% [SD]) than on transverse (51% +/- 22%) images, whereas the mean detection specificity was significantly (p = 0.005) higher (96% +/- 5% vs 95% +/- 6%, respectively). Reporting findings for significantly (p < 0.001) fewer coronal images (mean, 63.0 +/- 4.6 images) than transverse images (mean, 91.9 +/- 8.8 images) took significantly (p = 0.025) longer (mean, 263 +/- 56 sec vs 238 +/- 45 sec, respectively). CONCLUSION: Primary interpretation of thoracic MDCT is less sensitive and more time-consuming using 5-mm-thick coronal reformations as compared with transverse images.     

Routine isotropic computed tomography scanning of chest: value of coronal and sagittal reformations

OBJECTIVE: We sought to evaluate the usefulness of coronal and sagittal reformations from isotropic chest computed tomography (CT) examinations. METHODS: A total of 30 chest CT examinations were reconstructed into 2 sets of axial source images: 0.9-mm slice width with 0.45-mm reconstruction interval (isotropic) and 4-mm slices with 3-mm reconstruction interval. The isotropic dataset was reformatted into coronal and sagittal stacks with 4-mm slices. Three readers reviewed the image sets with 4-mm slice widths. Coronal and sagittal reformations were compared at the same sitting to axial images for depiction of anatomy and disease in the aorta, pulmonary arteries, hilar regions, mediastinum, lung parenchyma, pleura, diaphragm, thoracic spine, ribs, and trachea. A 5-point scale was used to determine whether nonaxial reformations showed anatomy and disease significantly better, somewhat better, same, somewhat worse or significantly worse than equivalent thickness axial source images. A 3-point scale was used to score if nonaxial image sets showed no, some, or significant additional information compared with the axial plane regarding the main diagnosis. RESULTS: There was better visualization of the hilar regions, diaphragm, spine, and trachea on the coronal reformations compared with source axial images (P < 0.05). Sagittal reformations scored better than axial source images for aorta, pleura, diaphragm, spine, and ribs (P < 0.05). The coronal and sagittal series showed significant additional information in 11% and 9% of patients, respectively. CONCLUSION: Radiologists should consider the use of one or both of coronal and sagittal planes in addition to the axial series in routine interpretation of chest CT.     

Detection of mediastinal and hilar lymph nodes by 16-row MDCT: Is contrast material needed?

PURPOSE: To retrospectively evaluate whether contrast administration is necessary in the detection of mediastinal and hilar lymph nodes when thin slice axial and coronal MDCT images are used. MATERIALS AND METHOD: This study was approved by our Institutional Review Board, informed consent was not required. Thirty-five patients who needed a chest CT (0.75 mm x 16) for various reasons were included. Four different image sets were reconstructed for each patient: non-enhanced axial (N-Ax), non-enhanced coronal MPR (N-Co), enhanced axial (E-Ax) and enhanced coronal MPR (E-Co). All the images were 1mm thick and interval. Two board-certified chest radiologists independently evaluated whether a lymph node with a short diameter, larger than 5mm, existed in each nodal station of the mediastinum and hilum. Two different board-certified chest radiologists assessed all four image sets together and established a reference standard by consensus. Interobserver agreement between the two readers was assessed by kappa statistics. Accuracy was calculated on each image set and compared to each other by McNemar's test. RESULTS: A total of 211 nodal stations, including 113 mediastinal and 98 hilar, were defined to be present and this was the reference standard. Except for N-Ax, the kappa values were within moderate to substantial (0.53-0.81). The accuracy for hilar nodes detection was significantly higher for the contrast enhanced images both in the axial (p<0.001) and coronal (p<0.01) data sets. The addition of contrast material did not significantly increase accuracy for the detection of mediastinal nodes (axial: p=0.542, coronal p=0.727). CONCLUSION: Contrast administration is recommended in the detection of hilar lymph nodes both on axial and MPR views, however, for assessment of mediastinal lymph nodes its contribution is low.     

Acute abdomen: Added diagnostic value of coronal reformations with 64-slice multidetector row computed tomography

RATIONALE AND OBJECTIVES: We sought to assess retrospectively the added value of coronal reformations from isotropic voxels obtained with 64-slice multidetector row computed tomography (CT) of the acute abdomen. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board and informed consent was waived. Multidetector helical 64-section CT (section thickness, 0.6 mm; pitch 1.75; table speed 35 mm/sec) was performed in 100 patients (60 women and 40 men; age range, 9-/+85 years; mean age, 45.2 years) with acute nontraumatic abdominal pain who had been referred from the emergency department. Axial images were reconstructed with 5-mm-thick sections at 5-mm intervals. The second data set was reformatted coronally, with 3-mm-thick sections at 3-mm intervals. Four independent, blinded readers with various level of training interpreted first the axial scans alone and then followed immediately by the coronal scans. Confidence in the visualization of anatomy and pathology was scored on a 5-point scale. The final diagnosis was determined by surgical and pathologic reports and by clinical follow-up in those who did not undergo surgery. RESULTS: Based upon the individual patient's clinical history and other comorbid factors, 92 patients received intravenous contrast and 90 patients received oral contrast. In 45 patients, no CT abnormalities were detected for an explanation of the abdominal pain. Mean sensitivity and specificity of axial CT alone were 92.5% and 91%, respectively. No significant differences in sensitivity and specificity were observed for the use of combined axial and coronal images. For the most inexperienced reader, the coronal reformations were helpful in 95% of cases, while for the most experienced reader, the coronal reformations were helpful in 35% of the cases. The coronal images were deemed helpful in an average of 62.3% of the cases for the four readers. However, diagnosing subtle pathology in the abdominal wall was difficult on coronal reformations alone. Overall, coronal reformations improved diagnostic confidence and interobserver agreement over axial images alone for visualization of normal abdominal structures and in the diagnosis of abdominal pathology. CONCLUSION: Axial and coronal reformations of 64-section multidetector row CT have equal sensitivity and specificity for the diagnosis of acute abdominal pathology. However, coronal reformations improved the diagnostic confidence for all readers but most significantly for the least experienced. Therefore, radiology departments with residents should consider routinely generating coronal images in patients with acute abdominal pain.     

Advantages of multidetector-row CT with multiplanar reformation in guiding percutaneous lung biopsies

PURPOSE: This study aimed to assess the usefulness of multiplanar reformations (MPR) during multidetector-row computed tomography (MDCT)-guided percutaneous needle biopsy of lung lesions difficult to access with the guidance of the native axial images alone owing to overlying bony structures, large vessels or pleural fissures. MATERIALS AND METHODS: MDCT-guided transthoracic needle biopsy (TNB) was performed on 84 patients (55 men and 29 women; mean age 65 years) with suspected lung neoplasm by using a spiral MDCT scanner with the simultaneous acquisition of six slices per rotation. We determined the site of entry of the 22-gauge Chiba needle on native axial images and coronal or sagittal MPR images. We took care to ensure the shortest needle path without overlying large vessels, main bronchi, pleural fissures or bony structures; access to the lung parenchyma as perpendicular as possible to the pleural plane; and sampling of highly attenuating areas of noncalcified tissue within the lesion. RESULTS: Diagnostic samples were obtained in 96% of cases. In 73 patients, lesions appeared as a solid noncalcified nodule <2 cm; 11 lesions were mass-like. In 22, the biopsy required MPR guidance owing to overlying ribs (18), fissures (2) or hilar-mediastinal location (2). CONCLUSIONS: MDCT MPR images allowed sampling of pulmonary lesions until now considered unreachable with axial MDCT guidance because of overlying bony structures (ribs, sternum and scapulae) or critical location (hilar-mediastinal, proximity to the heart or large vessels). Compared with the conventional procedure, the use of MPR images does not increase the rate of pneumothorax or the procedure time.     

MRI of the thorax during whole-body MRI: evaluation of different MR sequences and comparison to thoracic multidetector computed tomography (MDCT)

PURPOSE: To evaluate the accuracy of four MR sequences used as part of a whole-body MRI protocol to detect pulmonary lesions in cancer patients. MATERIALS AND METHODS: A total of 31 oncology patients were imaged in a 1.5T MR scanner (Magnetom Avanto; Siemens Medical Solutions, Germany) for whole-body staging. MR chest imaging included: axial and coronal T2-weighted (T2w)-short-tau inversion-recovery (STIR), axial T2w turbo spin-echo (TSE), and contrast-enhanced (CE) three-dimensional (3D) volumetric interpolated breathhold examination (VIBE). Multidetector computed tomography (MDCT) of the thorax served as the reference standard. The MDCT and MR images were evaluated independently by two radiologists. Comparative analysis was performed per lesion, per lobe, and per patient. Sensitivity, specificity, and predictive values were determined. RESULTS: Compared to MDCT that detected 268 pulmonary lesions ranging from 2 to 75 mm in diameter, the MR sensitivities were 91.1%, 92.5%, 90.8%, and 87.3% for the coronal STIR, the axial STIR, the axial T2w-TSE, and the axial CE 3D-VIBE, respectively. Undetected pulmonary lesions were either calcified or smaller than 10 mm in the axial diameter. With coronal STIR, six false-positive findings were detected; with axial STIR, 14 were detected; with axial T2w-TSE, 10 were detected; and with 3D-VIBE, seven were detected. CONCLUSION: Pulmonary MRI is feasible as part of a whole-body MRI protocol. In our study, STIR images achieved high accuracy compared to chest MDCT for pulmonary lesions of 3 mm in size or larger.     

Acute pulmonary embolism: comparison of standard axial MDCT with paddlewheel technique

PURPOSE: The purpose of this study was to evaluate the ability of rotated paddlewheel reformations for the detection of central and peripheral pulmonary embolism (PE) compared to standard axial multi detector CT (MDCT) images. MATERIAL AND METHODS: CT scans of 35 patients with PE were reviewed by three independent readers for the detection of pulmonary emboli using standard axial CT scans and reformatted paddlewheel technique. All images were evaluated in random order. MDCT examinations were performed with a collimation of 1.25 mm, a pitch of six and a reconstruction interval of 0.8mm. For each patient MIP were reformatted by using a paddlewheel arrangement with 5mm slab thickness and 5 degrees rotation. Standard of reference for PE was a consensus reading of the axial images by all three readers. RESULTS: The overall sensitivity for the axial images for the three readers ranged between 91% and 96%; for paddlewheel reformations from 78% to 83%; the specificity for both methods was 98-99%. Inter- and intraobserver agreement was also higher for axial images than for paddlewheel reformations. CONCLUSION: Comparing standard axial MDCT scans and reformatted paddlewheel images no significant difference for the detection of central PE was found, whereas for the detection of peripheral emboli standard axial images showed a significant higher percentage of detecting PE than paddlewheel reformations.     

Bildanalyse bei der Mehrschicht-Spiral-CT der Lunge mit MPR- und MIP-Rekonstruktionen

PURPOSE: To test, whether axial, coronal and sagittal MIP and MPR reconstructions of diagnostic quality can be obtained from 1-mm collimation MSCT data of the chest for the evaluation of thoracic anatomy and pathology. MATERIALS AND METHODS: 1-mm collimation MSCT scans were obtained with a pitch of 6 in an acrylic phantom and in 20 patients. Axial images were reconstructed with 0.6-mm increment. Multiplanar reformations (MPRs) and sliding thin-slab maximum intensity projections (STS-MIPs) were reconstructed in axial, coronal and sagittal planes. Images were printed in lung windows and evaluated by three readers by using a standardized evaluation scheme. RESULTS: Overall, both methods allowed good visualization of anatomic structures. MIP was superior for visualization of the pulmonary arteries (p < 0.05) while central and peripheral bronchi and the lung parenchyma were better depicted on multiplanar reconstructions. A confident diagnosis of thoracic pathology was feasible using both modalities, however MIPs appeared less usefull for evaluation of gross parenchymal abnormalities, such as pneumonic infiltrates or fibrotic changes. No significant difference in the degree of motion artifacts were detected between both modalities. CONCLUSION: MSCT data sets are ideally suited for generating MPR and MIP reconstructions. While MIPs are superior for the evaluation of thoracic vessels, MPR is advantageous for visualizing central and peripheral bronchi and the pulmonary parenchyma.     

多平面重建在弥漫性肺疾病中的应用价值

目的评价多层螺旋CT(MDCT)多平面重建(MPR)对肺弥漫性病变的诊断价值。资料与方法对67例经临床确诊表现为肺内弥漫性病变的病例进行MDCT扫描和薄层冠状位MPR,并与轴位高分辨率CT(HRCT)比较。图像分析共分3组,2人3次完成阅片。结果轴位HRCT和冠状位MPR评价磨玻璃密度影、气腔样实变和小结节等高密度病灶和含气病灶的敏感度分别是100%和87%～100%,特异性分别为100%和97%～100%,差别无显著性。HRCT和MPR图像在显示肺内细网状影、线样影和牵张性细支气管扩张的敏感度分别为92%～100%和71%～100%,特异性分别为88%～100%和90%～100%,差别无显著性。HRCT和MPR图像在评价肺弥漫性病变的分布上无显著性差别。观察者对MPR评价磨玻璃密度影、气腔样实变和蜂窝影、肺气肿、肺大泡的满意度较高(95%～100%);对线样影、细网状影、小结节或微结节、牵张性支气管扩张等的满意度较低(10%～68%),差别有显著性(P<0.05)。结论目前采用1.25mm准直的MDCT扫描所得的MPR图像在评价磨玻璃密度影、肺实变、蜂窝影和肺气肿、肺大泡等病变的能力等同于轴位HRCT;评价线样影、细网状影及牵张性支气管扩张和微结节等病变的能力不及轴位HRCT。     

Chest wall, lung, and pleural space trauma

Chest radiographs frequently underestimate the severity and extent of chest trauma and, in some cases, fail to detect the presence of injury. CT is more sensitive than chest radiography in the detection of pulmonary, pleural, and osseous abnormalities in the patient who has chest trauma. With the advent of multidetector CT (MDCT), high-quality multiplanar reformations are obtained easily and add to the diagnostic capabilities of MDCT. This article reviews the radiographic and CT findings of chest wall, pleural, and pulmonary injuries that are seen in the patient who has experienced blunt thoracic trauma.     

Coronal reformations of volumetric expiratory high-resolution CT of the lung

OBJECTIVE: The purposes of this study were to evaluate the quality of coronal reformatted images obtained from volumetric expiratory high-resolution CT imaging and to compare coronal and axial images with regard to their usefulness in detecting and characterizing air trapping. SUBJECTS AND METHODS. We studied 40 consecutive patients with known or suspected diffuse lung diseases with airway abnormalities who underwent volumetric expiratory high-resolution CT between May and July 2003. Respiratory motion artifacts were evaluated at upper, middle, and lower lung areas. Cardiac motion, beam-hardening, and other artifacts were evaluated throughout the lung fields. Detectability, clarity of borders, size, distribution, and extent of air trapping were compared on axial versus coronal end-expiratory high-resolution CT images. RESULTS: Respiratory motion artifacts were either imperceptible or not diagnostically limiting in all patients except three (7%) with diagnostically limiting image degradation at lower lung areas. Other diagnostically limiting image degradation was caused by beam-hardening artifacts in two patients (5%) and by quantum noise in two other patients (5%). The borders of air trapping were more clearly identified on coronal images than on axial images (grade 1 [vague], nine vs three; grade 2 [partially clear], 23 vs 21; grade 3 [completely clear], eight vs 16; median, two vs two; p = 0.001). The coronal reformatted images were as informative as axial images for detecting and assessing the classification and extent of air trapping. CONCLUSION: Coronal reformations of volumetric expiratory high-resolution CT scans were acceptable in image quality and provided additional value by affording clearer visualization of the borders of air trapping than was found in contiguous axial images.     

MDCT in emergency radiology: is a standardized chest or abdominal protocol sufficient for evaluation of thoracic and lumbar spine trauma?

OBJECTIVE: The objective of our study was to assess the diagnostic performance of a standardized 4-MDCT trauma protocol for the evaluation of the thoracic and lumbar spine in patients with multiple injuries. MATERIALS AND METHODS: Eighty-two patients with multiple injuries underwent MDCT for the chest and abdomen using a standardized 4-MDCT trauma protocol (collimation, 4 x 2.5 mm). Secondary reconstructions targeted to the spine were performed (slice width, 3 mm; reconstruction interval, 1.5 mm). All spinal fractures were additionally scanned using a collimation of 4 x 1 mm, and these images served as the standard of reference for fracture classification. An additional 50 patients with no spinal fracture served as the control group. A total of 65 major spinal fractures were present in 55 of the patients with multiple injuries. Two observers (observer 1 and observer 2) independently evaluated all CT data for spinal fractures using a 5-point confidence scale, classified the different fracture types, and rated the image quality of spinal structures on axial images and multiplanar reformations. RESULTS: Image quality for axial images was excellent in 80% and in 68% using 4 x 1 mm and 4 x 2.5 mm collimation, respectively. Image quality of the multiplanar reformations was excellent in 75% and good in 65% using 4 x 1 mm and 4 x 2.5 mm collimation, respectively. Spinal fractures were detected by observer 1 and observer 2 with a sensitivity and specificity of 98% and 97% and of 97% and 97%, respectively. Interobserver agreement regarding the confidence scale for fracture detection was substantial (kappa = 0.80), and agreement between the different imaging protocols for fracture classification was excellent for observer 1 (kappa = 0.95) and observer 2 (kappa = 0.97). CONCLUSION: Accurate evaluation of the thoracolumbar spine is possible with targeted image reconstruction based on a standardized 4-MDCT trauma protocol of the chest and abdomen.     

Significance of sagittal reformations in routine thoracic and abdominal multislice CT studies for detecting osteoporotic fractures and other spine abnormalities

The purpose was to assess osteoporotic vertebral fractures and other spinal lesions in sagittal reformations obtained from routine multidetector computed tomography (MDCT) studies of the thorax and abdomen, to compare sagittal reformations with axial images in detecting these lesions and to investigate how frequently they were missed in the official radiology report. Routine abdominal or thoracoabdominal MDCT using a standard protocol was performed in 112 postmenopausal women. Axial images and sagittal reformations were analyzed separately by two radiologists in consensus and were compared in order to evaluate how often spinal lesions could be detected. In addition the official radiology reports were assessed to determine how many of those abnormalities were identified. Spine abnormalities were visualized in 101/112 postmenopausal women. In 27 patients osteoporotic vertebral deformities were found; 6 of these were shown in the axial images, but none of these were diagnosed in the official radiology report. Additional abnormalities included degenerative disc disease, osteoarthritis of the facet joints, scoliosis, hemangiomas and bone metastases. In only 9/101 patients spine abnormalities were mentioned in the radiology report. Sagittal reformations of standard MDCT images provide important additional information on spinal abnormalities; in particular, osteoporotic vertebral deformities are substantially better detected.     

The impact of scan length on the exposure levels in 16- and 64-row multidetector computed tomography: a phantom study

RATIONALE AND OBJECTIVES: Higher patient exposure levels have been reported for 64-row multidetector computed tomography (MDCT) compared to 16-row MDCT. The objective of this study was to make a thorough comparison by evaluating the impact of scan length on the exposure levels at 16-row MDCT and 64-row MDCT. MATERIALS AND METHODS: Dose-length product (DLP) values were determined to compare exposure levels in 16- and 64-row MDCT. This phantom study does not deal with a possible reduction in image quality induced by an increase in scattered radiation in 64-row MDCT compared to 16-row MDCT. RESULTS: The exposure levels of 64-row MDCT (scan slice thickness, 0.5 mm) are up to 18% lower than those of 16-row MDCT at slice thickness 0.5 mm when scanning an object larger than 12.3 cm. At this value, the plots of the 16- and 64-row DLP values versus scan length cross. The DLP curves of 1- and 2-mm slice thickness 16-row MDCT are in closer resemblance to those of 0.5-mm 64-row MDCT. The respective exposure levels of 1- and 2-mm slice thickness 16-row MDCT exceed those of 0.5-mm 64-row MDCT by up to 4% and 3%, with intersections of 30 and 25 cm, respectively. CONCLUSION: Lower effective doses are obtained in 64-row MDCT compared to 16-row MDCT (0.5-mm slice thickness) provided that scan length exceeds 12.3, 30, and 25 cm, for 16-row MDCT slice thickness of 0.5, 1, and 2 mm, respectively. Reduced effective dosage in 64-row MDCT compared to 16-row MDCT has not been demonstrated before. Differences in object size may thus explain discrepancies between previous studies with regard to the exposure levels at 64-slice CT compared to 16-slice CT.     

Thin-section multiplanar reformats from multidetector-row CT data: utility for assessment of regional tumor extent in non-small cell lung cancer

PURPOSE: To determine the clinical utility of thin-section multiplanar reformats (MPRs) from multidetector-row CT (MDCT) data sets for assessing the extent of regional tumors in non-small cell lung cancer (NSCLC) patients. MATERIALS AND METHODS: Sixty consecutive NSCLC patients, who were considered candidates for surgical treatment, underwent contrast-enhanced MDCT examinations, surgical resection and pathological examinations. All MDCT examinations were performed with a 4-detector row computed tomography (CT). From each raw CT data set, 5mm section thickness CT images (routine CT), 1.25 mm section thickness CT images (thin-section CT) and 1.25 mm section thickness sagittal (thin-section sagittal MPR) and coronal images (thin-section coronal MPR) were reconstructed. A 4-point visual score was used to assess mediastinal, interlobar and chest wall invasions on each image set. For assessment of utility in routine clinical practice, mean reading times for each image set were compared by means of Fisher's protected least significant difference (PLSD) test. A receiver operator characteristic (ROC) analysis was performed to determine the diagnostic capability of each of the image data sets. Finally, sensitivity, specificity and accuracy of the reconstructed images were compared by McNemar test. RESULTS: Mean reading times for thin-section sagittal and coronal MPRs were significantly shorter than those for routine CT and thin-section CT (p<0.05). Areas under the curve (Azs) showing interlobar invasion on thin-section sagittal and coronal MPRs were significantly larger than that on routine CT (p=0.03), and the Az on thin-section sagittal MPR was also significantly larger than that on routine CT (p=0.02). Accuracy of chest wall invasion by thin-section sagittal MPR was significantly higher than that by routine CT (p=0.04). CONCLUSION: Thin-section multiplanar reformats from multidetector-row CT data sets are useful for assessing the extent of regional tumors in non-small cell lung cancer patients.     

Multislice CT of the pelvis: dose reduction with regard to image quality using 16-row CT

To optimize examination protocols of 16-row multi-detector CT (MDCT) of pelvis for dose reduction with regard to image quality. MDCT of pelvis was performed on 12 cadaver specimens with stepwise reduction of tube current from 160 mA (113, 80, 56, 40, 28) to 20 mA at 120 kV. Scan parameters were 16×1.5 mm collimation. Reconstructions of axial and coronal images were used for evaluation of cortex, trabeculum, image quality, image noise, acetabulum and iliosacral (ISJ) joints. After data were blinded, evaluation of images was done by three radiologists according to 5-point Likert scale. Accuracy of the observers in sorting films according to dose reduction was determined with kappa coefficient. Mean values of image evaluation were determined. Pronounced deterioration of image quality for all criteria was observed between 80 and 28 mA. Adequate image quality was obtained at 40 mA [effective dose (E): 2.2 mSv, CTDI_w: 2.8 mGy] for criterion detailed definition of acetabulum and ISJ and at 80 mA (E: 4.4 mSv, CTDI_w: 5.6 mGy) for remaining criteria. Moderate agreement was observed between the three observers (kappa coefficient: 0.31). All observers were excellent in arranging images according to decreasing dose. Using 16-row MDCT image quality of pelvis is acceptable at 80 mA and 120 kV. This translates into a dose reduction of 33% of average value of the nationwide survey of the German Roentgen Society (1999) for this type of examination.J. Gurung and M.F. Khan contributed in equal measure to this studyThis revised version was published online in April 2005 with corrections to author line and addresses.     

Complications of tracheal and thoracic surgery: the role of multisection helical CT and computerized reformations

Helical computed tomography (CT) has an important role in the evaluation of a wide range of congenital and acquired thoracic abnormalities. The development of advanced computerized reformations enables the generation of bronchographic and bronchoscopic images of the tracheobronchial tree, as well as angiographic images of pulmonary arteries and veins. Additionally, it provides coronal and sagittal reconstruction imaging of parenchymal abnormalities. This information is obtained by a 20-30s procedure on a typical single channel system, which makes helical CT an optimal technique for the evaluation of patients undergoing major upper airways and thoracic interventions. The recent introduction of multisection CT scanners allows faster imaging of patients with thinner collimation, thus improving spatial resolution along the longitudinal (z) axis of the patient along with reduction of motion artefacts. This article demonstrates the use of dual and quad-section helical CT in the postoperative evaluation of patients undergoing laryngo-tracheal and thoracic interventions, including laryngoplasty, tracheal endoscopic laser ablation, lobectomy, pneumonectomy, lung transplantation, sleeve resection, pulmonary angioplasty, and pulmonary artery thromboendarterectomy. Emphasis is given to the additive value of using computerized reformations over axial images, especially for delineation of complex postoperative anatomical details in the tracheobronchial tree and pulmonary vasculature.