CT scout view as an essential part of CT reading

Supplementary value and diagnostic performance of computed tomography scout view in the detection of thoracolumbar spine injuries

PURPOSE

Assessing the diagnostic performance and supplementary value of whole-body computed tomography scout view (SV) images in the detection of thoracolumbar spine injuries in early resuscitation phase and identifying frequent image quality confounders.

METHODS

In this retrospective database analysis at a tertiary emergency center, three blinded senior experts independently assessed SV to detect thoracolumbar spine injuries. The findings were categorized according to the AO Spine classification system. Confounders impacting SV image quality were identified. The suspected injury level and severity, along with the confidence level, were indicated. Diagnostic performance was estimated using the caret package in R programming language.

RESULTS

We assessed images of 199 patients, encompassing 1592 vertebrae (T10-L5), and identified 56 spinal injuries (3.5%). Among the 199 cases, 39 (19.6%) exhibited at least one injury in the thoracolumbar spine, with 12 (6.0%) of them displaying multiple spinal injuries. The pooled sensitivity, specificity, and accuracy were 47%, 99%, and 97%, respectively. All experts correctly identified the most severe injury of AO type C. The most common image confounders were medical equipment (44.6%), hand position (37.6%), and bowel gas (37.5%).

CONCLUSION

SV examination holds potential as a valuable supplementary tool for thoracolumbar spinal injury detection when CT reconstructions are not yet available. Our data show high specificity and accuracy but moderate sensitivity. While not sufficient for standalone screening, reviewing SV images expedites spinal screening in mass casualty incidents. Addressing modifiable factors like medical equipment or hand positioning can enhance SV image quality and assessment.

Determining body height and weight from thoracic and abdominal CT localizers in pediatric and young adult patients using deep learning

In this retrospective study, we aimed to predict the body height and weight of pediatric patients using CT localizers, which are overview scans performed before the acquisition of the CT. We trained three commonly used networks (EfficientNetV2-S, ResNet-18, and ResNet-34) on a cohort of 1009 and 1111 CT localizers of pediatric patients with recorded body height and weight (between January 2013 and December 2019) and validated them in an additional cohort of 116 and 127 localizers (acquired in 2020). The best-performing model was then tested in an independent cohort of 203 and 225 CT localizers (acquired between January 2021 and March 2023). In addition, a cohort of 1401 and 1590 localizers from younger adults (acquired between January 2013 and December 2013) was added to the training set to determine if it could improve the overall accuracy. The EfficientNetV2-S using the additional adult cohort performed best with a mean absolute error of 5.58 ± 4.26 cm for height and 4.25 ± 4.28 kg for weight. The relative error was 4.12 ± 4.05% for height and 11.28 ± 12.05% for weight. Our study demonstrated that automated estimation of height and weight in pediatric patients from CT localizers can be performed.

Pediatric age estimation from thoracic and abdominal CT scout views using deep learning

Age assessment is regularly used in clinical routine by pediatric endocrinologists to determine the physical development or maturity of children and adolescents. Our study investigates whether age assessment can be performed using CT scout views from thoracic and abdominal CT scans using a deep neural network. Hence, we retrospectively collected 1949 CT scout views from pediatric patients (acquired between January 2013 and December 2018) to train a deep neural network to predict the chronological age from CT scout views. The network was then evaluated on an independent test set of 502 CT scout views (acquired between January 2019 and July 2020). The trained model showed a mean absolute error of 1.18 ± 1.14 years on the test data set. A one-sided t-test to determine whether the difference between the predicted and actual chronological age was less than 2.0 years was statistically highly significant (p < 0.001). In addition, the correlation coefficient was very high (R = 0.97). In conclusion, the chronological age of pediatric patients can be assessed with high accuracy from CT scout views using a deep neural network.

Scout it out! Wake-Up Stroke Protocol to Expedite MRI in Stroke Patients

In wake-up stroke patients, magnetic resonance imaging (MRI) is useful to identify patients that would benefit from thrombolytic therapy. Our multidisciplinary stroke team developed and implemented a workflow to rapidly identify patients that are able to safely undergo an MRI exam, thus decreasing time to treatment. We employ a full-body CT scout image in our CT head protocol for acute stroke in order to identify implantable devices and foreign bodies. This protocol highlights the importance of radiology playing an active role on the multidisciplinary stroke team in order to effectively and promptly treat patients.

The CT scout view: complementary value added to abdominal CT interpretation

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.

[Radiation Exposure in Computed Tomography Localizer Radiograph]

This research measured the radiation exposure of the computed tomography(CT) localizer radiograph of the trunk of the body. The entrance surface dose for CT localizer radiograph was measured using radiophotoluminescent glass dosimeter(RPLD) on four points of measurement, including the center of the phantom, on the surface of a phantom placed in the center of a CT bed, assuming that the subject has a thickness of 20 cm. The entrance surface dose of the localizer radiograph under the chest CT protocol manufacturer's initial setting conditions of 120 kV 35 mA was 0.80 mGy at the center and 0.53 for the 4-location average for the upper X-ray tube (excluding the CT bed), and 0.74 mGy at the center and 0.48 mGy for the 4-location average for the lower X-ray tube (including the CT bed). Compared to the Japan DRLs 2015 chest X-ray (P→A), the entrance surface dose was 2.67 times at the center and 1.77 times for the 4-location average for the upper X-ray tube and 2.47 times at the center and 1.60 times for the 4-location average for the lower X-ray tube. The CT radiation dose also cannot be ignored for the localizer radiograph entrance surface dose.

Retained wound protector following abdominal surgery

Medical devices which have been erroneously retained postoperatively has been a persisting problem encountered over many decades, despite rigid protocols and preventative measures being put in place. We present a case of a retained wound protector detected on CT following abdominal surgery, the first published report of its kind to our knowledge. Radiologists reporting the images should be familiar with commonly used medical devices. This case also highlights the importance of reviewing the CT scout imaging as an essential part of the study, particularly in the recognition of foreign bodies or medical devices. We re-emphasise the importance of effective and timely communication with the surgical team, should there be any suspicion of retained surgical appliance.

Radiological mass casualty incident (MCI) workflow analysis: single-centre data of a mid-scale exercise

OBJECTIVE

The aim of the study was to analyse and interpret radiological mass casualty incident workflow data.

METHODS

In a mid-scale mass casualty incident exercise, the on-site triage assigned 12 cases to the investigated institution (11 included in the study). Two out of five institutional multislice-CT-scanners were used and the whole CT workflow and radiological service process chain were simulated as close to realistic as possible. The respective time intervals for reaching defined milestones were measured.

RESULTS

The average CT in-room time, i.e. from entering to leaving the CT room was 9.43 min [(standard deviation) SD: 2.27 min; 95% (confidence interval) CI: 7.90-10.95 min]. Time spent on CT table was 6.75 min (SD: 1.67; CI: 5.63-7.87), and the pure scan time was 4.22 min (SD: 0.64; CI: 3.79-4.65). The first images after entering the CT room were available at a dedicated CT workstation after 5.85 min (SD: 2.20; CI: 4.37-7.32) and institution wide via picture archiving system (PACS) after 7.85 min (SD: 1.27; CI: 7.00-8.71). However, the PACS archiving process, that is, transfer of standard reconstruction set of CT images into the PACS was finished after 20.85 min (SD: 2.97; CI: 18.85-22.84).

CONCLUSION

Up to six patients may be served per hour and per CT scanner by using a standard whole body CT polytrauma protocol. Dedicated CT triage protocols may even increase this number. The time portion until images were available at end points was relatively long. A solution has to be developed in order to avoid scenarios of patients being faster at end points than their images.

Precision and Accuracy of Measurements on CT Scout 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 CT scout view: does it need to be routinely reviewed as part of the CT interpretation?

OBJECTIVE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

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

PURPOSE

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.

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 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.

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.