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Computed tomography (CT) scout images, also known as CT localizer radiographs, topograms, or scanograms, are an important, albeit often overlooked part of the CT examination. Scout images may contain important findings outside of the scanned field of view on CT examinations of the abdomen and pelvis, such as unsuspected lung cancer at the lung bases. Alternatively, scout images can provide complementary information to findings within the scanned field of view, such as characterization of retained surgical foreign bodies. Assessment of scout images adds value and provides a complementary "opportunistic" review for interpretation of abdominopelvic CT examinations. Scout image review is a useful modern application of conventional abdominal radiograph interpretation that can help establish a diagnosis or narrow a differential diagnosis. This review discusses the primary purpose and intent of the CT scout images, addresses standard of care and bias related to scout image review, and presents a general systematic approach to assessing scout images with multiple illustrative examples, including potential pitfalls in interpreting scout images.

There have been some reports of gross trunnion failure (GTF) in total hip arthroplasty. Here, we report a case of GTF 19 years after bipolar hemiarthroplasty using a 28-mm head with a 14/16 taper bore. Compared to other GTF reports, the current case had some unusual aspects: bipolar hemiarthroplasty, 28-mm head, relatively late-onset, and no apparent findings of metallosis though a severe one was evident. A Computed tomography scout view provided valuable information in evaluating polyethylene, metal head, and neck inside the bipolar cup. The current report suggests a need for concerned regarding short trunnion length which may be associated with GTF.

Information on medical devices embedded in the body is important in the identification of an unidentified body. Computed tomography (CT) is a powerful imaging modality; however, metallic artifacts deteriorate the image quality because of the reconstruction method. On the contrary, CT scout view is less affected by metallic artifacts compared to CT. It is a simple method to classify the body into three rough parts for postmortem CT (PMCT) scout view, and an algorithm used to detect the location of the implanted metal has been developed for personal identification in forensic pathology. Of the test images, 97% were correctly classified into the three body parts. The true-positive rate for detection of the implanted metal in the scout view was 96.5%. Therefore, our simple methods are applicable in PMCT scout views and would be particularly useful for forensic pathology.

PURPOSE To compare the radiation dose and image quality using the conventional method for performing the front and side scout view and a new method for performing the side scout view, and then correct the table height at the scan isocenter and perform the front scout view. METHODS We retrospectively analyzed fifty-six children who had underwent computed tomography (CT) examination between June 2014 and August 2018. We divided them into two groups. The conventional method was performed in 3 steps: 1. obtain the front scout view, 2. obtain the side scout view, and 3. main scan. Without table position correction, the new method was performed in 4 steps: 1. obtain the side scout view with table position correction, 2. patient correction at the scan isocenter, 3. obtain the front scout view, and 4. main scan. We used a 64-row CT scanner (LightSpeed VCT; GE Healthcare). Scan parameters were tube voltage 80 kV, automatic tube current modulation, noise index 16, slice thickness 5 mm, rotation time 0.4 s/rot, helical pitch 1.375, and reconstruction kernel standard. We recorded the volume dose index (CTDIvol) and dose length product (DLP) on the CT console and compared the radiation dose in both groups. To evaluate the image quality in both groups, the mean standard deviation of CT number (SD value) was measured within an approximately 5-10 mm2 circular region of interest. We measured the scan length of the pediatric patient and accuracy of pediatric positioning at the CT examination. A grid was displayed on the CT axial image, taken to evaluate the error from the scan isocenter during alignment, and the error between the height of half the body thickness and the scan isocenter was recorded. RESULTS Scan lengths were median (minimum-maximum) values of 16.2 cm (10.8-21.5 cm) and 16.8 cm (11.5-23.0 cm). There were no significant differences in the scan length between both groups (p=0.47). In the group with table position correction, median (minimum-maximum) values for CTDIvol, DLP and SD value were 0.40 mGy (0.3-0.7 mGy), 7.6 mGy･cm (4.4-11.5 mGy･cm), and 24.0 HU (18.3-37.5 HU), respectively. In the group without the table position correction, median (minimum-maximum) values for CTDIvol, DLP and SD value were 0.40 mGy (0.3-0.6 mGy), 7.1 mGy･cm (4.2-13.8 mGy･cm), and 20.3 HU (11.3-28.8 HU), respectively. There were no significant differences in the CTDIvol and DLP values between both groups (p=0.42 and p=0.44, respectively); however, there were significant differences in the SD value in both groups (p

Introduction We present the CT scan-derived turricephaly index (TI) as a quotient of the maximal occipito-frontal length of the skull to the distance from the centre of the sella to the highest point on the vertex as a validated tool for assessing turricephaly and evaluating surgical techniques aimed at reducing it. Materials and methods Measurements taken from CTs of non-operated children with Apert syndrome and age-matched controls were analysed using Centricity PACS system (from the lateral scout image) and the thick-sliced Osirix tool. CTs from non-operated children with Apert syndrome were used to investigate the natural history of their turricephaly both as a group and individually. Results There was statistically significant agreement between measurements taken from the CT scout and Osirix for 42 control children (R2 = 0.97) and 42 children with Apert syndrome (R2 = 0.98) and between two separate observers. There was a statistically significant difference (p 2) CT's showed a similar decrease in turricephaly in the individual child (p Conclusions TI derived from the CT scout view provides a simple, objective and validated method for assessing turricephaly. We recommend it for monitoring and for the prospective evaluation of reconstructive techniques in children with complex/syndromic craniosynostosis.

For CT pulmonary angiograms, a scout view obtained in anterior–posterior projection is usually used for planning. For bolus tracking the radiographer manually locates a position in the CT scout view where the pulmonary trunk will be visible in an axial CT pre-scan. We automate the task of localizing the pulmonary trunk in CT scout views by deep learning methods. In 620 eligible CT scout views of 563 patients between March 2003 and February 2020 the region of the pulmonary trunk as well as an optimal slice (“reference standard”) for bolus tracking, in which the pulmonary trunk was clearly visible, was annotated and used to train a U-Net predicting the region of the pulmonary trunk in the CT scout view. The networks’ performance was subsequently evaluated on 239 CT scout views from 213 patients and was compared with the annotations of three radiographers. The network was able to localize the region of the pulmonary trunk with high accuracy, yielding an accuracy of 97.5% of localizing a slice in the region of the pulmonary trunk on the validation cohort. On average, the selected position had a distance of 5.3 mm from the reference standard. Compared to radiographers, using a non-inferiority test (one-sided, paired Wilcoxon rank-sum test) the network performed as well as each radiographer (P

Radiation exposure from coronary computed tomography angiography (CCTA) remains a cause for concern. The objective of this study was to investigate whether using the coronary artery calcium score scan (CACS) would reduce the radiation dose for CCTA scanning and the overall radiation exposure (ORE).In total, 256 patients were examined with a third-generation dual-source CT (n = 200) or 256-row CT (n = 56), among whom 105 (Group A) and 28 patients (Group B), respectively, underwent CCTA with CACS for field of view planning. The remaining patients, with the scout view for field of view planning, constituted Group A1 and B1. The scanning parameter settings were standardized between groups.Shorter scan lengths were observed in Group A (9.98 ± 0.79 cm) compared to Group A1 (13.64 ± 1.79 cm; p0.001), which also resulted in a lower dose-length product (DLP) in Group A (115.04 ± 64.13) relative to Group A1 (138.67 ± 68.87; p0.05). Similarly, shorter scan lengths were found in Group B (14.92 ± 1.17 cm) compared to Group B1 (15.79 ± 0.63 cm; p = 0.001); this resulted in a lower DLP (322.07 ± 45.39) compared to Group B1 (354.34 ± 65.27; p = 0.036). The CACS resulted in an increase in ORE in both groups.CACS may have a critical role in the reduction of radiation dose in CCTA scanning, but the potential effectiveness of CACS in reducing ORE is weak.

Objective The aim of this study was to present our experience on the evaluation of suspected illicit drug carriers via computerized tomography scout view (CTSV) with analysis of detectability and features such as content, form and density. Methods A total of 120 individuals suspected of body packing were screened via CT in a university emergency department between January 2014 and December 2017. Results 88.3% of 120 body packing cases examined in the study were male. The median (1st quartile–3rd quartile) age of the cases was 35.5 (30–41) years. We found that solid packs have a 4.573-fold higher likelihood of detection in CTSV screening than liquid ones (95%CI: 1.879–11.134). Additionally, the number of CT scans needed were significantly associated with capsule localization (stomach) (OR:7.178, 95%CI: 2.420–21.293) and solid form packs (OR: 8.705, 95%CI: 2.318–32.692) are associated with number of CT scans. Conclusion CTSVs have a successful detection rate, especially in solid form packs. Our results suggest that conclusive CTSV imaging for body packing may be recommended to delay the application of the next CT scan until the passage of the first capsule; thereby preventing unnecessary radiation exposure.

Purpose: The purpose of this study has been to evaluate the diagnostic information contained in the CT scout view in the detection of body packing. Materials and methods: Retrospect analysis of 43 CT scans between July 2011 and June 2013 in asymptomatic suspects of body packing (29 men, 14 females, mean age 38 ± 9 years). Results: A total of 11 positive cases of body packing were identified. In 10 (91%) of the cases packets were relatively large and spares in number (3 or less); in 7 (64%) a single packet has been identified. 6 (55%) of the packets were located rectally, 4 (36%) vaginally and in 1 (9%) case multiple small packets of approximately 1 cm in size were found to have been ingested orally. Maximum and minimum diameters were 5.9 ± 3 cm and 2.9 ± 1.4 cm, respectively. The mean weight of packets was 7.5 ± 4.2 g (range 2 - 54 g). In 73% (n = 8) heroin had been detected; other drugs such as cocaine (n = 1) and cannabis (n = 1) were encountered once, respectively. One packet was identified retrospectively and its content could therefore not be identified. The average effective dose was 3.8 ± 2.1 mSv for CT, of that 0.12 ± 0.01 mSv was required for the CT scout view. Conclusion: If CT scout view were treated as a diagnostic image, some CT scans may be omitted, thereby maintaining streamlined operations and achieving further dose reduction jointly in the workup of body packing.

Six to eleven percent of important findings are excluded in the CT FOV, and 2% of these can be seen on the scout film, thus highlighting its importance [Johnson et al., AJR Am J Roentgenol. 202:1256–1263, 2014]. Leonard Berlin’s article, reviewing the CT scout view: medicolegal and ethical considerations, admits that the scout film is unlikely to demonstrate a significant abnormality; however, because 85 million CT scans are performed a year, the scout film could help to identify nearly 2.5 million abnormalities not included on the CT scan FOV [Berlin, AJR Am J Roentgenol. 202:1264–1266, 2014]. The value of the scout film cannot be overstated; it provides an overview of the patient’s condition. Review of the scout film helps you to identify lines and tubes that you may otherwise have ignored. Orthopedic hardware assessment is facilitated on the scout film as is foreign body recognition. Scoliosis can be measured on the scout film [Ho et al., Spine (Phila PA 1976). 17:771–774, 1992]. Diaphragmatic elevation can be quantified on this view.

Objectives The purposes of this study were to (1) investigate the limits of measurements on scout view in three computed tomography axes, x , y and z and (2) develop a model to provide better understanding of measurement accuracy. Methods For the first objective, anteroposterior and lateral scout views of a Catphan phantom 200 mm in diameter and length were acquired with a GE scanner at 21 different table heights. Phantom measurements on scout view were performed by two experienced readers. The comparison of their measures provided estimation of precision. The accuracy was assessed by determining the bias, calculated as the difference between the values measured on scout view and the real phantom size. Second, a model was developed investigating the relationship between the dimensions of the object, its image, and the table height. This relationship was tested on our data. Results Scout view measurements were precise, with less than 0.53% difference between readers. In addition, small biases of about 1 mm were detected in the z -axis, whatever the table height. In the other axes, serious biases from −13 to +73 mm were measured. Furthermore, at isocentre, overestimations up to 7 mm were shown. The results also indicated that biases in scout view measurements are because of the geometrical projection related to the object-detector distance. Conclusions Measurements in the table movement axis are precise and accurate, conferring to scout views an added value for preoperative planning in orthopedic surgery.

The objective of our study was to determine whether the CT scout view should be routinely reviewed by comparing diagnostic information on the scout view with that provided by the correlative CT study.Two radiologists blinded to history and CT findings reviewed retrospectively 2032 scout views. All cases with major findings (defined as any abnormality that would prompt additional diagnostic tests or require management) were correlated with the CT study, other imaging study, or medical record when necessary by a third radiologist to determine the validity of the scout view finding and whether the finding was identifiable on the current CT study.Major findings were identified in 257 (13%, reader 1) and 436 (23%, reader 2) of cases. Most major findings were confirmed (69-78%) or refuted (13-16%) by the CT study. However, 15 (6%, reader 1) and 48 (11%, reader 2) of the major findings were not included in the CT FOV, of which five (2%, reader 1) and 21 (5%, reader 2) constituted a missed pathologic finding. The most common one was cardiomegaly detected on a nonchest CT scout view. Additional pathologic findings included fracture, metastasis, avascular necrosis or subluxation of the humeral head, dilated bowel, and thoracic aortic dilatation. The most common false-positive finding was cardiomegaly.In a small percentage of cases, review of the CT scout view will disclose significant pathologic findings not included in the CT FOV. The results of this study support the routine inspection of the scout view, especially for the detection of pathologic findings in anatomic regions not imaged by CT.

OBJECTIVE. The purpose of this article is to share the views of an experienced expert witness in medical malpractice cases on the use of CT scout images. CONCLUSION. The medical literature has resurrected issues regarding viewing of CT scout images. Scout images are an integral part of any CT examination and should be carefully reviewed for findings that may or may not be included in the FOV of the study.

ObjectivesThe study evaluated the relationship between cardiac computed tomography (CT) scout view x-ray attenuation and CT image noise compared with weight or body mass index (BMI).BackgroundDecreasing peak tube voltage from 120 to 100 kVp on the basis of body size reduces radiation exposure. Methods to better predict CT image noise may lead to more effective selection of reduced tube voltage in cardiac CT.MethodsImage quality was graded subjectively (1 [excellent] to 4 [nondiagnostic]) and objectively (SD of the aortic attenuation value) in cardiac CT angiograms (N = 106) acquired at either 100 or 120 kVp. X-ray attenuation characteristics on the scout view (120 kVp, 30 mA) were measured within a 3-cm region of interest across the chest in the frontal x-ray. Receiver-operating characteristic curve analysis was performed comparing scout view attenuation versus weight and BMI in predicting CT image noise and quality.ResultsCT image noise correlated with both BMI (r = 0.40; p < 0.001) and the scout view attenuation value (r = 0.52; p < 0.001). In linear regression models with controlling for BMI (or weight) and tube potential, scout view attenuation was the best predictor of the CT image noise (p < 0.001), and increased model fit statistic from 0.23 to 0.41 (p model

OBJECTIVE To determine the frequency of power injectable peripherally inserted central venous catheter (PIPICC) displacement after contrast injection for computed tomography. MATERIALS AND METHODS We included all patients who had a computed tomographic examination with contrast administration via PIPICC over a 4-month period. Several variables including catheter location before and after the injection were documented. Descriptive statistics were used for continuous variables. The χ² test was used to compare groups. Continuous variables were analyzed using the Student t test. RESULTS Among 78 injections in 67 patients (34 men and 33 women; median age, 49 years), there were 12 catheter displacements (15.4%): 5 (62.5%) of 8 catheters initially located proximal to the tracheobronquial angle (TBA) and 7 (10.14%) of 69 catheters initially located distal to the TBA. The initial catheter position before the injection correlated with the frequency of displacement significantly (P < 0.006). Contrast injection rate and amount of contrast were no risk factors for position change. There were no complications. CONCLUSION Catheter displacement occurred in 62.5%, with PIPICCS cephalad to the TBA. A preliminary scout view should be checked before the contrast injection. In addition, a postinjection scan scout view is recommended to verify catheter position.

AJR:202, June 2014 mal by a hospital staff radiologist, the boy was discharged from the ED with a diagnosis of “mild concussion.” Two hours after being discharged from the hospital ED, the boy began convulsing and was rushed back to the hospital ED. Now semicomatose, the boy underwent another unenhanced head CT examination that revealed a large epidural hematoma with a linear parietal bone fracture. Emergency surgery was performed, but the boy never regained consciousness and died shortly thereafter. The family filed a medical malpractice lawsuit naming as codefendants the ED physician who was employed by the hospital and the radiologist who was a member of the hospital’s independent radiology group. At his discovery deposition, the defendant-radiologist was asked by the plaintiff’s attorney to review the boy’s initial CT study that had been interpreted as normal (Fig. 1A). The attorney asked the radiologist if, in retrospect, he would still interpret the CT study as normal, and the radiologist answered affirmatively. The attorney then asked the radiologist to look at and interpret the second head CT study that had been performed on the patient’s readmission to the ED (Fig. 1B). “It shows a large epidural hematoma, which I reported,” said the radiologist. The plaintiff’s attorney now asked the radiologist to look at the scout view that had been obtained in conjunction with the initial CT study and state what he saw on it. “There is a horizontal linear parietal bone fracture,” responded the radiologist. “Did you report the fracture when you originally read the Reviewing the CT Scout View: Medicolegal and Ethical Considerations

The aim of the current study was to compare the diagnostic information obtained from a helical CT examination in low severity cervical spine trauma with that from a lateral CT scout view. We included alert and clinically stable patients, who had suffered acute blunt trauma of low or moderate severity. Their scout images were interpreted independently by two radiologists and the final outcome of the CT exam which was the gold standard. Patient dose was assessed using Monte-Carlo techniques. In 52 of our studies (45%), at least the first five cervical vertebrae were visible with adequate quality, and in 16.5% of the scout views (19 studies) all 7 vertebrae were depicted with excellent quality. Overall sensitivity and specificity of scout view was 70% and 100%, respectively. There were three false negative and one false positive cases. The effective dose value was estimated to be 0.02 mSv which is at least two orders of magnitude lower than that from a CT scan. When clinical examination is not suggestive of a C1-C2 fracture, adequate depiction of an intact cervical spine at the scout view, without proceeding to a full CT scan, is a sufficient dose and time-effective imaging approach.

Chest tomosynthesis, which refers to the principle of collecting low-dose projections of the chest at different angles and using these projections to reconstruct section images of the chest, is an imaging technique recently introduced to health care. The main purpose of the present work was to determine the average effective dose to patients from clinical use of chest tomosynthesis. Exposure data for two chest radiography laboratories with tomosynthesis option (Definium 8000 with VolumeRAD option, GE Healthcare, Chalfont St. Giles, UK) were registered for 20 patients with a weight between 60 and 80 kg (average weight of 70.2 kg). The recorded data were used in the Monte Carlo program PCXMC 2.0 (STUK-Radiation and Nuclear Safety Authority, Helsinki, Finland) to determine the average effective dose for each projection. The effective dose for the chest tomosynthesis examination, including a scout view and the tomosynthesis acquisition, was finally obtained by adding the effective doses from all projections. Using the weighting factors given in ICRP 103, the average effective dose for the examination was found to be 0.13 mSv, whereas the average effective dose for the conventional two-view chest radiography examination was 0.05 mSv. A conversion factor of 0.26 mSv Gy(-1) cm(-2) was found suitable for determining the effective dose from a VolumeRAD chest tomosynthesis examination from the total registered kerma-area product. In conclusion, the effective dose to a standard-sized patient (170 cm/70 kg) from a VolumeRAD chest tomosynthesis examination is ~2 % of an average chest CT and only two to three times the effective dose from the conventional two-view chest radiography examination.

SUMMARY Our aim was to determine the degree of bias in CT scanogram measurements. We obtained standard lateral and anteroposterior (AP) pelvimetry scanograms of a phantom pelvis after placing ball bearings or aluminium rods to mark bony landmarks. Computed tomography pelvimetry was carried out at the manufacturer-recommended table height on two commercial CT scanners and at 10-mm increments up to 50 mm above and below this height. The AP inlet, AP outlet, interspinous distance and transverse diameters were each measured three times for each scanogram. The true measurements were obtained directly from the disassembled phantom. Bias was defined as the difference between the CT measurement and the true measurement. Observer error was negligible. The transverse diameter was overestimated at high table positions and underestimated at low table positions on both scanners (1 6t o210 mm). After correcting for geometric distortion, up to 6 mm bias was still present. The point at which no bias occurred was different for each scanner and did not correspond to the manufacturers’ recommended table height. The outlet was overestimated on both scanners by up to 5 mm. The true inlet measurement was overestimated by 1.2 mm. The interspinous distance was minimally underestimated on both scanners. The measurements on CT scanogram were underestimated or overestimated in an inconsistent and unpredictable fashion, varying from one type of measurement to another and from CT scanner to CT scanner. This has implications for the accuracy and clinical utility of measurements obtained from a CT scanogram.

Aim: The aim of this study was to determine whether measuring the trabecular bone density in one lumbar vertebra (L) instead of three has an effect on the assessment of bone density in children. Materials and Methods: Bone density was measured in 70 patients (38 male, 32 female), ages 1 to 22 years (mean age 12.4, median 13 years) using a Somatom Balance Scanner (Siemens). The trabecular bone density was measured (1-cm slice, 80 kV, 81 mAs) in L1 through L3. Results: The mean bone density in the lumbar vertebrae was 139.9 mg/ml calcium-hydroxylapatite per ml bone in L1,133.9 in L2, and 131.7 in L3, and the mean of all three vertebrae was 135.2 mg/ml. Measurements in L1 were 4.7 mg/ml (standard deviation [SD] 4.7 mg/ml) above the mean value of the three upper lumbar vertebrae. The density in L2 was 1.3 mg/ml below the mean (SD 3.1 mg/ml). On average, L3 was 3.5 mg/ml below the mean (SD 4.6 mg/ml). This minor systematic deviation in the measurement values for the individual vertebrae from the mean value was so low that there was no statistical evidence for a deviation from an ideal regression line. Conclusions: When using an adequate technique, especially accurate analysis of the topogram (scout view) and the tomogram, measurement of the bone density of one lumbar vertebra provides satisfactory information regarding the trabecular bone density in children, but the values differ in the three upper lumbar vertebrae. The bone density of L2 is close to the mean of the upper three vertebrae. In the case of pathologic values or a pathologic trabecular pattern, three vertebrae should be measured.

A 63-year-old Malay woman had a 6-French dual-lumen power-injectable peripherally inserted central catheter (PICC) inserted and subsequently underwent a contrast-enhanced computed tomography scan with intravenous contrast medium administered via the PICC. After the scan, the tip of the PICC was noted to have displaced from its original position and lodged in 1 of the small branches of the right subclavian vein. This phenomenon was then demonstrated in real time under fluoroscopy during the process of repositioning the PICC tip. Although power-injectable PICCs are designed for use with power injectors, tip displacement can and does happen. A computed tomography scout view of the chest may be necessary after each use of power injectors to confirm that the PICC tip remains in a satisfactory position.

When unenhanced CT reveals ureterolithiasis, some patients will require baseline or follow-up conventional radiography to help guide clinical management. We sought to determine the sensitivity of routinely obtained scout radiographs for revealing stones to determine if the scout view can be used in place of baseline conventional radiography.We retrospectively reviewed the CT scout radiographs in conjunction with axial CT images in a series of 215 consecutive patients in whom CT revealed a single ureteral stone. On the scout radiographs, stones were classified as definitely visible, definitely not visible, or indeterminate. In addition, a phantom was constructed using fragments of kidney stones to evaluate the effect of the digital scout kilovoltage settings on stone visualization.Forty-nine percent of stones were definitely visible on scout radiography, 47% were definitely not visible, and 4% were indeterminate. Four stones larger than 10 mm that were not visible on scout radiography were composed of uric acid (n = 2) or xanthine (n = 2). Scout radiographs of the phantom determined an optimal kilovoltage setting of 80-100 kVp to visualize stones less than 3 mm, whereas stones greater than or equal to 3 mm were visible at all kilovoltage settings.In our series, 49% of ureteral stones were visible on the often-overlooked routine CT scout radiograph. Imaging of phantoms showed that stone visualization can be optimized by using the lowest kilovoltage settings. Therefore, the CT scout view can be used as a baseline study in patients requiring follow-up radiography and for planning treatment of patients requiring lithotripsy or other intervention. Finally, large stones not visible on scout radiographs are likely composed of uric acid or xanthine.

Custom has come to dictate an inadequate evaluation of the abdomen by allowing the kidney ureters and bladder study (KUB) to be deemed equivalent to a full study of the supine abdomen. The reason for this suboptimal approximation is related to architectural imperatives, traditional practice, and landmark studies favoring horizontal beam projections. Now, using the digital scout view in conjunction with contemporaneous computed tomography, the diagnostic importance of the uppermost abdomen, positioned beyond the superior limit of a KUB, can be demonstrated, and its sensitivity can be measured for the recognition of pneumoperitoneum. In large patients, a two-view supine abdominal series can overcome the neglect of the subdiaphragmatic region, improving our capability to recognize free air, even when its volume is less than 1 cc.

CT, with all its potentialities, seems to be the best imaging alterative in complex maxillary clefts. The lateral “scout view” of the CT allows a true cephalometric evaluation. Three-dimensional osseous and teeth images can be reconstructed from the usual axial sections, without further radiation. They offer a superb anatomical and practical approach in three dimensions yielding a precise determination of osseous defects and of teeth location. This study demonstrates, in particular, the advantages of the direct and precise approach to the dental structures included in bone by means of 3-D “dental” reconstruction at a threshold value between 1000 and 1500 Hounsfield units (HU), eliminating bony structures. The reconstruction allows exact spatial visualization of all the tooth structures included in bone without any distortion or superimposition as is encountered on pantographic and lateral cephalometric radiography. CT provides all the required information in one examination, facilitating preorthodontic or presurgical treatment planning in patients with complex maxillary clefts from the prepubertal period to adulthood.

Scout views are digital radiographs obtained to aid planning of the subsequent computed tomography (CT) examination. Review of these scout views may provide additional information not demonstrated on the axial images, but such reviews may not necessarily be performed routinely, especially in the context of abdominopelvic CT studies. We illustrate the value of the scout images by presenting a series of representative cases of missed pulmonary neoplasms in five patients who originally underwent such examinations.

Purpose Computed tomography (CT) is an important firstline imaging tool in pediatric neuroradiology. The scout view (SV) is essential for planning the CT study. It is frequently underestimated for its diagnostic value but may harbor important diagnostic clues. We present and discuss the role of SVin the accurate interpretation of pediatric neuroradiological CT studies. Methods CT studies have been collected over 12 months by an experienced pediatric neuroradiologist. Retrospective evaluation of SV and axial CT images was performed in nine children, where the SV gave important diagnostic information. Abnormalities on SV were classified as (1) located outside the field of view as imaged by the cross-sectional CT slices or (2) located in the plane of the cross-sectional CT slices or orthogonal to it. Results Five male and four female patients were included. The mean age at CTwas 9.86 years (range, 0.75 to 19 years). Abnormalities on SV were located outside of the field of view as imaged by cross-sectional CT slices in six out of nine children and were within the plane of the CTslices or orthogonal to it in three out of nine children. Conclusions A thorough and accurate evaluation of the SV may add valuable, clinically relevant information and should be a routine part of the interpretation of each pediatric neuroradiological CT study.

Micro computed tomography (micro-CT) is a widely-used imaging technique. A challenge of micro-CT is to quantitatively reconstruct a sample larger than the field-of-view (FOV) of the detector. This scenario is characterized by truncated projections and associated image artifacts. However, for such truncated scans, a low resolution scout scan with an increased FOV is frequently acquired so as to position the sample properly. This study shows that the otherwise discarded scout scans can provide sufficient additional information to uniquely and stably reconstruct the interior region of interest. Two interior reconstruction methods are designed to utilize the multi-resolution data without a significant computational overhead. While most previous studies used numerically truncated global projections as interior data, this study uses truly hybrid scans where global and interior scans were carried out at different resolutions. Additionally, owing to the lack of standard interior micro-CT phantoms, we designed and fabricated novel interior micro-CT phantoms for this study to provide means of validation for our algorithms. Finally, two characteristic samples from separate studies were scanned to show the effect of our reconstructions. The presented methods show significant improvements over existing reconstruction algorithms.

Interpretation of CT colonography frequently is difficult because of imaging pitfalls. These pitfalls may be a source of false negative and false positive findings. The pictorial review in this chapter focuses on some important issues of colonic imaging with CT colonography and at each time proposes a solution.

The purpose of this chapter is to provide a practical guide for setting up a computed tomographic colonography (CTC) practice commencing with processing the initial request by a potential patient or clinician, selecting the patient cathartic and tagging agent (these issues are detailed in Chap. 6, “Patient Preparation and Tagging”), training technologists in performing the actual CTC exam (scanning and insufflation), training radiologists in interpreting the exam, and concluding with guidelines for communicating the results.

To obtain consistent CCTA image quality and patient dose optimization with an individualized tube current selection method based on analysis of CT scout scans.The study received a waiver of informed consent from the institutional review board. Initially 100 patients (Group A) underwent CCTA with a fixed mA. The scout view pixel value and CCTA image noise were measured. Their correlation was studied to establish a formula to determine the required mA for obtaining a CT exam with a specific image noise. One hundred patients (Group B) were then scanned with the formula-determined mA. CCTA image quality, image noise and effective dose from the two groups were statistically analyzed. CT findings for 32 Group B patients were compared with the conventional coronary angiography.An average CCTA image noise of 27.6 HU was obtained (target 27 HU) using the formula with more uniform image noise in Group B (standard deviation 2.4 HU) than in Group A (4.1 HU). There was no statistical difference between image quality scores for the two groups. The effective dose for Group B (7.8 mSv) was 30% lower than for Group A (11.2 mSv) (p0.01). CCTA sensitivity, specificity, positive predictive value, negative predictive value, and stenosis detection accuracy were 94.9%, 92.1%, 88.9%, 96.5% and 93.2%, respectively, for stenosis greater than 50%.CCTA mA selection based upon the image characteristics of the CT scout view provides an individualized protocol that generates consistent image quality and helps to reduce overall patient dose.

The objective of our study was to prospectively investigate the effect of adjusting the scan length of CT coronary angiography using the calcium scoring images instead of the scout view with regard to radiation dose.One hundred twenty-five consecutive patients (mean age +/- SD, 62 +/- 10 years) undergoing both calcium scoring and CT coronary angiography were included in our study. The scan length of calcium scoring was planned on the scout view; the scan length of CT coronary angiography was planned on the axial images of the calcium scoring by identifying the origin of the left main artery and cardiac apex and adding 1 cm cranially and caudally. Effective radiation doses were calculated for CT coronary angiography using both scout view-derived and calcium scoring-derived scan lengths.The scout view-derived scan length (mean +/- SD, 139 +/- 13 mm) was significantly greater than the calcium scoring-derived scan length (117 +/- 9 mm; p0.01). The average radiation dose was 0.8 +/- 0.3 mSv (range, 0.6-1.5 mSv) for calcium scoring and 9.0 +/- 0.6 mSv (range, 6.5-10.2 mSv) for CT coronary angiography. Using the scout view-derived scan length would have been associated with an effective radiation dose of 10.7 +/- 1.2 mSv (mean +/- SD) for CT coronary angiography, which is significantly higher than that using the calcium scoring-derived scan length (p0.05). The average difference between CT coronary angiography using a calcium scoring-derived scan length and that using a scout view-derived scan length was 1.7 +/- 0.9 mSv, corresponding to a radiation dose reduction of 16%. The average dose reduction when using a calcium scoring-derived instead of a scout view-derived scan length for CT coronary angiography-including the radiation dose of the calcium scoring scan-was 1.2 +/- 0.8 mSv (range, 0.1-2.7 mSv) (p0.05).Adjustment of the scan length of CT coronary angiography using the images from calcium scoring instead of the scout view is feasible and is associated with a 16% reduction in radiation dose of dual-source CT coronary angiography.