Scout View Research Articles

Spectrum of Signs of Pneumoperitoneum

Pneumoperitoneum is caused by rupture of a hollow viscus that includes the stomach, small bowel, and large bowel, with the exception of those portions that are retroperitoneal in the duodenum and colon. The causes of pneumoperitoneum are numerous, ranging from iatrogenic and benign causes to more life-threatening conditions. In the absence of a benign cause of pneumoperitoneum, the identification of free intraperitoneal gas usually indicates the need for emergency surgery to repair a perforated bowel. The plain film is the primary diagnostic tool for detecting pneumoperitoneum: multiple signs of free intraperitoneal air can be found especially on supine abdominal radiographs. Computed tomography (CT) examination has been shown to be more sensitive than abdominal radiographs for the detection of free intraperitoneal air. It is important that the radiologist become familiar with the signs of pneumoperitoneum that can be discerned on abdominal radiographs, on CT scout view, and on CT scan.

Patient-specific tube-voltage selection at coronary CT angiography based on the combination of X-ray attenuation on scout views and body mass index: how can appropriate radiation dose be achieved?

Body weight, body mass index (BMI), and scout X-ray radiographic attenuation can be used to predict image noise on computed tomographic coronary angiography (CTCA) images. To use a formula to predict patient-specific image noise and then select an appropriate CTCA patient-specific tube voltage for better radiation control. Forty-eight patients who underwent CTCA imaging at 120 kVp were reviewed, and their patient information and scouting X-ray radiographic attenuations were recorded to identify the best correlations between patient data and image noise and to develop a predicted image noise formula. Subsequently, 54 patients subjected to scanning at 100 or 120 kVp, depending on the noise predicted by our formula, were prospectively studied. Two radiologists visually assessed the image quality of the right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) by consensus readings. The predicted image noise = 0.939 BMI + 0.025 scouting attenuation + 20.16. The median value of the overall image noise was 30.55 HU at 120 kVp and 29.85 HU at 100 kVp. The mean visual evaluation scores at 100 and 120 kVp were 3.25 and 3.24 for the proximal RCA, 3.40 and 3.26 for the proximal LAD, and 3.30 and 3.15 for the proximal LCX, respectively. The BMI and scouting X-ray radiographic attenuation can be combined to predict the CTCA image noise. Our prediction formula is useful for deciding when to switch from the 120- to the 100-kVp technique.

Concept for quantifying the dose from image guided radiotherapy.

BackgroundRadiographic image guidance is routinely used for patient positioning in radiotherapy. All radiographic guidance techniques can give a significant radiation dose to the patient. The dose from diagnostic imaging is usually managed by using effective dose minimization. In contrast, image-guided radiotherapy adds the imaging dose to an already high level of therapeutic radiation which cannot be easily managed using effective dose. The purpose of this work is the development of a concept of IGRT dose quantification which allows a comparison of imaging dose with commonly accepted variations of therapeutic dose.MethodsIt is assumed that dose variations of the treatment beam which are accepted in the spirit of the ALARA convention can also be applied to the additional imaging dose. Therefore we propose three dose categories: Category I: The imaging dose is lower than a 2 % variation of the therapy dose. Category II: The imaging dose is larger than in category I, but lower than the therapy dose variations between different treatment techniques. Category III: The imaging dose is larger than in Category II. For various treatment techniques dose measurements are used to define the dose categories. The imaging devices were categorized according to the measured dose.ResultsPlanar kV-kV imaging is a category I imaging procedure. kV-MV imaging is located at the edge between category I and II and is for increasing fraction size safely a category I imaging technique. MV-MV imaging is for all imaging technologies a category II procedure. MV fan beam CT for localization is a category I technology. Low dose protocols for kV CBCT are located between category I and II and are for increasing fraction size a category I imaging technique. All other investigated Pelvis-CBCT protocols are category II procedures. Fan beam CT scout views are category I technology. Live imaging modalities are category III for conventional fractionation, but category II for stereotactic treatments.ConclusionsDose from radiotherapy imaging can be categorized in terms of generally accepted dose variations of therapy dose. This concept allows the quantification of daily dose from image guided radiotherapy in the spirit of the ALARA convention.

The Risk of Mistaking Intestinal Lanthanum Carbonate for Intestinal Bleeding on CT.

Dear Editor, A 65 year-old male was referred to our department of radiology for investigation of rectorrhagia. The patient had a history of hypercholesterolemia, arterial hypertension, type II diabetes, intestinal polyps, diverticulosis, and monoclonal gammopathy leading to chronic renal failure requiring recurrent hemodialysis. During the previous week, the patient had been suffering from severe pulmonary infection accompanied by septic shock with hepatitis. Gastroscopy and colonoscopy were unable to find the cause of the bleeding because of a lack of compliance to the preparation diet. A computed tomography was requested to locate the source of the bleeding. The pre-contrast acquisition showed a number of spontaneously hyper-dense elements throughout the whole intestinal tract, inside the bowel lumen, from the stomach to the rectum exhibiting very sharp edges (better seen on the scout view). The opacities determined marked attenuation of X-rays with densities around 2500 Hounsfield Units (HU) and significant beam-hardening artifacts (Fig. 1). It was first thought that the patient had ingested some kind of foreign body (as suggested by the appearance on the scout examination) that could explain the intestinal bleeding, which he denied. There was also no history of a recent administration of oral contrast. No other relevant cause of bleeding per rectum was found on the CT-scan images. The patient stopped bleeding in the meantime without further intervention. Clinicians from the hemodialysis unit pointed out that the patient had been receiving oral lanthanum carbonate for the last couple of days (1000 mg per day). Lanthanum carbonate is used in the treatment of hyperphosphatemia, often occurring in patients with chronic renal failure. Binding the alimentary phosphate, it reduces the absorption of phosphate in the small bowel. Lanthanum is a heavy metallic element of the third group of the periodic table (the lanthanides), which also includes barium and gadolinium. Its nature itself thereby explains why tablets of lanthanum carbonate exhibit such marked X-rays attenuation. As it has been reported, well-chewed LETTER TO THE EDITOR

Precision and Accuracy of Measurements on CT Scout View

ObjectivesThe 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. MethodsFor 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. ResultsScout 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. ConclusionsMeasurements in the table movement axis are precise and accurate, conferring to scout views an added value for preoperative planning in orthopedic surgery.

TU-CD-207-11: Patient-Driven Automatic Exposure Control for Dedicated Breast CT

Purpose: To implement automatic exposure control (AEC) in dedicated breast CT (bCT) on a patient-specific basis using only the pre-scan scout views. Methods: Using a large cohort (N=153) of bCT data sets, the breast effective diameter (D) and width in orthogonal planes (Wa,Wb) were calculated from the reconstructed bCT image and pre-scan scout views, respectively. D, Wa, and Wb were measured at the breast center-of-mass (COM), making use of the known geometry of our bCT system. These data were then fit to a second-order polynomial “D=F(Wa,Wb)” in a least squares sense in order to provide a functional form for determining the breast diameter. The coefficient of determination (R2) and mean percent error between the measured breast diameter and fit breast diameter were used to evaluate the overall robustness of the polynomial fit. Lastly, previously-reported bCT technique factors derived from Monte Carlo simulations were used to determine the tube current required for each breast diameter in order to match two-view mammographic dose levels. Results: F(Wa,Wb) provided fitted breast diameters in agreement with the measured breast diameters resulting in R2 values ranging from 0.908 to 0.929 and mean percent errors ranging from 3.2% to 3.7%. For all 153 bCT data sets used in this study, the fitted breast diameters ranged from 7.9 cm to 15.7 cm corresponding to tube current values ranging from 0.6 mA to 4.9 mA in order to deliver the same dose as two-view mammography in a 50% glandular breast with a 80 kV x-ray beam and 16.6 second scan time. Conclusion: The present work provides a robust framework for AEC in dedicated bCT using only the width measurements derived from the two orthogonal pre-scan scout views. Future work will investigate how these automatically chosen exposure levels affect the quality of the reconstructed image.

Thoracic Pathologies on Scout Views and Bolus Tracking Slices for Computed Tomographic Cerebral Angiography.

To evaluate the incidence of additional thoracic pathologic findings (TPF) detected on scout views and corresponding bolus tracking slices (SVBT) for computed tomographic cerebral angiography (CTCA) and to test the reliability and accuracy of these findings. The study collective included 505 consecutive patients who underwent multidetector CTCA. Appendant SVBT of all patients were reviewed for any pathologic findings and patient medical reports were analyzed, if any medical treatment was initiated for the detected pathologic findings. In 18 patients thoracic CT scans were performed in the same session. These were additionally reviewed by two blinded observers to test for intra- and interobserver reliability as well as for accuracy of detecting thoracic pathologies on SVBT. TPF were detected in 165 (33%) SVBT. The five most common pathologic findings were: pleural effusion, 12%; pneumonia, 8%; atelectasis/dystelecatsis, 6%; pericardial effusion, 2% and elevated diaphragm, 1%. For 48 % of these findings medical treatment was initiated. SVBT showed a sensitivity of 53%, a specificity of 99%, a positive predictive value of 89%, a negative predictive value of 94% and accuracy of 94% for the detection of TPF. The intraobserver reliability was very good and the interobserver reliability showed moderate agreement. SVBT for CTCA should be reviewed with care by radiologists, since additional TPF can affect patient management. Nevertheless, despite a high specificity of SVBT for detecting TPF, an only moderate sensitivity has to be taken into account. Thoracic pathologies are frequently found on scout views for cerebral CTA. Reviewing additional bolus trigger slices will improve diagnostic sensitivity. Despite high specificity, scout views and trigger slices offer a moderate sensitivity. Evaluation of scout views and trigger slices can result in medical treatment.

Head Computed Tomography in the Emergency Department: A Collection of Easily Missed Findings that are Life-Threatening or Life-Changing

BackgroundThe use of noncontrast head computed tomography (CT) has become commonplace in the emergency department (ED) as a means of screening for a wide variety of pathologies. Approximately 1 in 14 ED patients receives a head CT scan, and analyzing and interpreting this high volume of images in a timely manner is a daily challenge. ObjectivesMinimizing interpretation error is of paramount importance in the context of life-threatening and time-sensitive diagnoses. Therefore, it is prudent for the physician to recognize particular pitfalls in head CT interpretation and establish search patterns and practices that minimize such errors. In this article, we discuss a collection of common ED cases with easily missed findings, and identify time-effective practices and patterns to minimize interpretation error. DiscussionThere are numerous reasons for false-negative interpretations, including, but not limited to, incomplete or misleading clinical history, failure to review prior studies, suboptimal windowing and leveling, and failure to utilize multiple anatomic views via multi-planar reconstructions and scout views. We illustrate this in four specific clinical scenarios: stroke, trauma, headache, and altered mental status. ConclusionAccurate and timely interpretation in the emergent setting is a daily challenge for emergency physicians. Knowledge of easily overlooked yet critical findings is a first step in minimizing interpretation error.

The CT scout view: does it need to be routinely reviewed as part of the CT interpretation?

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.

Reviewing the CT scout view: medicolegal and ethical considerations.

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

Significant incidental findings in 9-year old children undergoing cardiovascular magnetic resonance imaging for research

Background The management of incidental findings in research imaging is a contentious issue. The imaging field of view in cardiovascular magnetic resonance imaging (CMR) studies often extends well beyond the cardiac anatomy, particularly on initial scout views. In clinical CMR there is limited data on incidental extra-cardiac findings in adults and even less in children. In research studies we are unaware of any data on incidental findings (cardiac or extra-cardiac) involving CMR of children. The aim of this study was to report on significant incidental findings noted in a research cohort of healthy children undergoing CMR. Methods

Common Blind Spots on Chest CT: Where Are They All Hiding? Part 2, Extrapulmonary Structures

W671 axial images (Fig. 1). For example, findings such as dilated bowel loops suggestive of bowel obstruction or important skeletal abnormalities within the lower cervical or upper lumbar spine that warrant further investigation may not be seen on the axial images. The interpreting radiologist is responsible for all images in the study, including the scout view. The initial impression formed on the basis of the scout image, correlated immediately with the corresponding CT findings, can also help improve the radiologist’s ability to interpret chest radiograph.

Imaging dose assessment for IGRT in particle beam therapy

IntroductionImage-guided advanced photon and particle beam treatments are promising options for improving lung treatments. Extensive use of imaging increases the overall patient dose. The aim of this study was to determine the imaging dose for different IGRT solutions used in photon and particle beam therapy. Material and methodsMeasurements were performed in an Alderson phantom with TLDs. Clinically applied protocols for orthogonal planar kV imaging, stereoscopic imaging, CT scout views, fluoroscopy, CT, 4D-CT and CBCT were investigated at five ion beam centers and one conventional radiotherapy department. The overall imaging dose was determined for a patient undergoing a lung tumor irradiation with institute specific protocols. ResultsOAR doses depended on imaging modality and OAR position. Dose values were in the order of 1mGy for planar and stereoscopic imaging and 10–50mGy for volumetric imaging, except for one CBCT device leading to lower doses. The highest dose per exam (up to 150mGy to the skin) was recorded for a 3-min fluoroscopy. DiscussionModalities like planar kV or stereoscopic imaging result in very low doses (∼1mGy) to the patient. Imaging a moving target during irradiation, low-dose protocols and protocol optimization can reduce the imaging dose to the patient substantially.

Scout view in pediatric CT neuroradiological evaluation: do not underestimate!

Computed tomography (CT) is an important first-line 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 SV in the accurate interpretation of pediatric neuroradiological CT studies. 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. Five male and four female patients were included. The mean age at CT was 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 CT slices or orthogonal to it in three out of nine children. 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.

Caseous calcification of the mitral annulus.

A 61-year-old asymptomatic woman was referred for echocardiography to evaluate recently detected systolic murmur. Transthoracic echocardiography revealed an echodense obstructive mass in the left ventricular outflow tract of unclear origin. Subsequent transesophageal echo suggested an intracardiac calcified tumor and recommended surgical excision. Contrast-enhanced cardiac computed tomography (CT) confirmed a well-defined lobulated mass adherent to the anterior mitral valve leaflet, the non-enhanced scout view revealed marked hyper-attenuation confirming diffuse calcification. Caseous calcification was diagnosed and surgery was deferred. Caseous calcification is typically benign and most commonly involves the posterior mitral annulus. Our patient displayed an atypical location of exuberant mitral annular calcification.

M.R.I diagnosis of tumours and tumour-like conditions affecting the pterygopalatine fossa.

To create awareness to the radiologist and clinicians for the magnetic resonance imaging (MRI) appearance of Pterygopalatine fossa (PTF) tumours and to evaluate the role of MRI in the diagnostic of PTF lesions. Retrospective evaluation of MRI features of 29 patients with pathologically proved pterygopalatine fossa (PTF) lesions was performed. The study included 18 males and 11 females with ages ranging between 15 and 68 years. All patients were examined on 1.5 Tesla magnets before and after injection of Gadolinium Meglumine. TI WI 5mm section sagittal scout views, followed by axial T1 5mm sections for the skull base and same sliced thickness during PD and T2 WI in axial and coronal planes. MRI features of various masses in pterygopalatine fossa were reviewed and correlated with those demonstrated in the literatures. Out of 29 PF masses, 7 masses were proved to be angiofibroma and 6 were nasopharyngeal carcinoma, entering the PTF. MRI is a useful imaging test which helps in the differential diagnosis of pterygopalatine fossa lesions with precise evaluation of their extensions and nature of lesion and helping to reach the correct diagnosis. However, MRI has limitation for evaluation of associated bony erosion, for which adjuvant CT scan is needed.

Dislodgement of a Power-Injectable Peripherally Inserted Central Catheter After Power Injection: A Case Report

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.

Missed Lung Cancers on the Scout View: Do We Look Every Time?

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.

A comparative study of linear measurements of facial skeleton using computed tomography and traditional cephalometry

Background: Radiographic imaging is an important adjunct in the assessment of skeletal and dental relationships for the orthodontic patient. Imaging is one of the most ubiquitous tools used by orthodontists to measure and record the size and form of craniofacial structures. Materials and Methods: The objectives of the study were to compare the measurements from human skulls and their images from cephalometric radiographs and computed tomography (CT) scanograms in order to gauge the potential use of CT in routine clinical practice. Based on the specific criteria including stable occlusion and condyles fitting stably in glenoid fossa, 15 dry human skulls were selected. Lateral, posteroanterior cephalograms, and CT scout views were taken of each skull by standardized methods. Linear measurements were made on all three records. Intraclass correlation coefficients, Pearson's correlation coefficient and regression constant were calculated to assess the records. Results: The linear measurements of the cephalometric record are greater than CT measurements on scout images. In vertical plane, the CT projections are more coinciding with the direct skull measurements. In sagittal and transverse planes, the cephalometric measurements were more correlating with the direct skull measurements. Conclusions: The cephalograms and CT scanograms differed in accuracy of linear measurements, because of variation in the location and size of an object, within the imaged 3D structure of both records.

Systematic measurements of whole‐body imaging dose distributions in image‐guided radiation therapy

The full benefit of the increased precision of contemporary treatment techniques can only be exploited if the accuracy of the patient positioning is guaranteed. Therefore, more and more imaging modalities are used in the process of the patient setup in clinical routine of radiation therapy. The improved accuracy in patient positioning, however, results in additional dose contributions to the integral patient dose. To quantify this, absorbed dose measurements from typical imaging procedures involved in an image-guided radiation therapy treatment were measured in an anthropomorphic phantom for a complete course of treatment. The experimental setup, including the measurement positions in the phantom, was exactly the same as in a preceding study of radiotherapy stray dose measurements. This allows a direct combination of imaging dose distributions with the therapy dose distribution. Individually calibrated thermoluminescent dosimeters were used to measure absorbed dose in an anthropomorphic phantom at 184 locations. The dose distributions from imaging devices used with treatment machines from the manufacturers Accuray, Elekta, Siemens, and Varian and from computed tomography scanners from GE Healthcare were determined and the resulting effective dose was calculated. The list of investigated imaging techniques consisted of cone beam computed tomography (kilo- and megavoltage), megavoltage fan beam computed tomography, kilo- and megavoltage planar imaging, planning computed tomography with and without gating methods and planar scout views. A conventional 3D planning CT resulted in an effective dose additional to the treatment stray dose of less than 1 mSv outside of the treated volume, whereas a 4D planning CT resulted in a 10 times larger dose. For a daily setup of the patient with two planar kilovoltage images or with a fan beam CT at the TomoTherapy unit, an additional effective dose outside of the treated volume of less than 0.4 mSv and 1.4 mSv was measured, respectively. Using kilovoltage or megavoltage radiation to obtain cone beam computed tomography scans led to an additional dose of 8-46 mSv. For treatment verification images performed once per week using double exposure technique, an additional effective dose of up to 18 mSv was measured. Daily setup imaging using kilovoltage planar images or TomoTherapy megavoltage fan beam CT imaging can be used as a standard procedure in clinical routine. Daily kilovoltage and megavoltage cone beam computed tomography setup imaging should be applied on an individual or indication based protocol. Depending on the imaging scheme applied, image-guided radiation therapy can be administered without increasing the dose outside of the treated volume compared to therapies without image guidance.