Recurrent CT, cumulative radiation exposure, and associated radiation-induced cancer risks from CT of adults

External validation of the CHOKAI score for the prediction of ureteral stones: A multicenter prospective observational study

OBJECTIVE

The CHOKAI and STONE scores are clinical prediction rules to predict ureteral stones in patients presenting with renal colic. Both systems contribute to reducing diagnostic radiation exposure; however, few studies have compared the two scoring systems. Therefore, we aimed to compare these systems and assess their diagnostic accuracy for ureteral stones.

METHODS

This was a multicenter prospective observational study performed between 2017 and 2018, including patients aged >15 years with renal colic and suspected with ureteral stones. We calculated the CHOKAI and STONE scores of each patient based on their medical interviews and physical and laboratory findings. Primary outcome was differences in the area under the receiver operating characteristic curve in each model, and secondary outcome was diagnostic accuracy at the optimal cut-off point.

RESULTS

Of the 124 patients included, 84 were diagnosed with ureteral stones. The area under the curve of the CHOKAI score was 0.95, showing a sensitivity of 0.93, specificity of 0.90, positive likelihood ratio of 9.3, and negative likelihood ratio of 0.079, at an optimal cut-off point of 6. The area under the curve of the STONE score was 0.88, showing a sensitivity of 0.68, specificity of 0.90, positive likelihood ratio of 6.8, and negative likelihood ratio of 0.36, at an optimal cut-off point of 9. Thus, the area under the curve was significantly higher for the CHOKAI score than for the STONE score (p = 0.0028).

CONCLUSIONS

The CHOKAI score has a diagnostic performance superior to that of the STONE score in this population.

Feasibility of low dose chest CT for virtual bronchoscopy navigation in a porcine model

BACKGROUND

Virtual bronchoscopy navigation (VBN) is widely used for assistance in the histological examination of lung nodules. However, little is known about the optimal CT radiation dose for VBN. Therefore, we performed an animal study to evaluate the feasibility of low dose CT (LDCT) for VBN.

METHODS

Ten pigs underwent standard dose CT (as a reference) and four different LDCT protocols: LDCT 1, 120 kVp, 15 mAs; LDCT 2, 120 kVp, 8 mAs; LDCT 3, 100 kVp, 7 mAs; and LDCT 4, 100 kVp, 4 mAs. As targets for the VBN, 10 mm virtual lesions were created in the central and peripheral bronchi. To assess the performance of the VBN, the navigation direction (direction of reconstructed pathways to the target) and the number of branching's (the number of peripheral bronchi to the target) were evaluated.

RESULTS

The mean effective doses significantly differed across the four LDCTs (P <  0.001). For both central and peripheral virtual targets, there were significant differences in the accuracy of the navigation direction and the number of branching's of the VBNs across the four LDCTs (P <  0.001 for all). Regarding the accuracy of the navigation direction and the number of branching's, the areas under the curves of the ROCs were 0.9352 and 0.9324, respectively, for central virtual targets, and 0.8696 and 0.8783, respectively, for peripheral virtual targets. Youden's index indicated that the optimal effective CT scan dose for both central and peripheral virtual targets was 0.238 mSv.

CONCLUSIONS

LDCT is feasible for VBN.

Adaptive, Iterative, Long-Term Personalized Therapy Management in a Case of Stage IV Refractory NSCLC

In this paper we report long-term therapy management based on iterative de novo molecular and cellular analysis in a case of metastatic non-small cell lung cancer (NSCLC), with prior history of treated colorectal cancer. In the described case temporal tumor evolution, emergent therapy resistance and disease recurrences were addressed via the administration of personalized label- and organ-agnostic treatments based on de novo tumor profiling. This adaptive and iterative treatment strategy countered disease progression at each instance and led to the durable regression of primary as well as metastatic lesions. Concurrently, serial evaluation of mutations in cell-free circulating tumor DNA (ctDNA) via liquid biopsy (LBx) was performed to monitor disease status, ascertain treatment response, identify emergent drug resistance and detect recurrence at sub-radiological levels. The treatment management strategy described herein effectively addressed multiple, sequential clinical conundrums for which viable options were unavailable under the current Standard of Care (SoC).

Virtual versus true non-contrast dual-energy CT imaging for the diagnosis of aortic intramural hematoma

PURPOSE

To assess whether virtual non-contrast (VNC) images derived from contrast dual-layer dual-energy computed tomography (DL-DECT) images could replace true non-contrast (TNC) images for aortic intramural hematoma (IMH) diagnosis in acute aortic syndrome (AAS) imaging protocols by performing quantitative as well as qualitative phantom and clinical studies.

MATERIALS AND METHODS

Patients with confirmed IMH were included retrospectively in two centers. For in vitro imaging, a custom-made phantom of IMH was placed in a semi-anthropomorphic thorax phantom (QRM GmbH) and imaged on a DL-DECT at 120 kVp under various conditions of patient size, radiation exposure, and reconstruction modes. For in vivo imaging, 21 patients (70 ± 13 years) who underwent AAS imaging protocols at 120 kVp were included. In both studies, contrast-to-noise ratio (CNR) between hematoma and lumen was compared using a paired t test. Diagnostic confidence (1 = non-diagnostic, 4 = exemplary) for VNC and TNC images was rated by two radiologists and compared. Effective radiation doses for each acquisition were calculated.

RESULTS

In both the phantom and clinical studies, we observed that the CNRs were similar between the VNC and TNC images. Moreover, both methods allowed differentiating the hyper-attenuation within the hematoma from the blood. Finally, we obtained equivalent high diagnostic confidence with both VNC and TNC images (VNC = 3.2 ± 0.7, TNC = 3.1 ± 0.7; p = 0.3). Finally, by suppressing TNC acquisition and using VNC, the mean effective dose reduction would be 40%.

CONCLUSION

DL-DECT offers similar performances with VNC and TNC images for IMH diagnosis without compromise in diagnostic image quality.

KEY POINTS

• Dual-layer dual-energy CT enables virtual non-contrast imaging from a contrast-enhanced acquisition. • Virtual non-contrast imaging with dual-layer dual-energy CT reduces the number of acquisitions and radiation exposure in acute aortic syndrome imaging protocol. • Dual-layer dual-energy CT has the potential to become a suitable imaging tool for acute aortic syndrome.

What Physicians and Health Organizations Should Know About Mandated Imaging Appropriate Use Criteria

The Appropriate Use Criteria Program, enacted by the Centers for Medicare & Medicaid Services in response to the Protecting Access to Medicare Act of 2014 (PAMA), aims to reduce inappropriate and unnecessary imaging by mandating use of clinical decision support (CDS) by all providers who order advanced imaging examinations (magnetic resonance imaging; computed tomography; and nuclear medicine studies, including positron emission tomography). Beginning 1 January 2020, documentation of an interaction with a certified CDS system using approved appropriate use criteria will be required on all Medicare claims for advanced imaging in all emergency department patients and outpatients as a prerequisite for payment. The Appropriate Use Criteria Program will initially cover 8 priority clinical areas, including several (such as headache and low back pain) commonly encountered by internal medicine providers. All providers and organizations that order and provide advanced imaging must understand program requirements and their options for compliance strategies. Substantial resources and planning will be needed to comply with PAMA regulations and avoid unintended negative consequences on workflow and payments. However, robust evidence supporting the desired outcome of reducing inappropriate use of advanced imaging is lacking.

Structural lung abnormalities on computed tomography correlate with asthma inflammation in bronchoscopic alveolar lavage fluid

Objective: Image scoring systems have been developed to assess the severity of specific lung abnormalities in patients diagnosed with various pulmonary diseases except for asthma. A comprehensive asthma imaging scoring system may identify specific abnormalities potentially linking these to inflammatory phenotypes.Methods: Computed tomography (CT) images of 88 children with asthma (50 M/38 F, mean age 7.8 ± 5.4 years) acquired within 12 months of bronchoscopic alveolar lavage fluid (BALF) sampling that assessed airway inflammation cell types were reviewed along with CT images of 49 controls (27 M/22 F, mean age 3.4 ± 2.2 years). Images were scored using a comprehensive scoring system to quantify bronchiectasis (BR), bronchial wall thickening (BWT), ground glass opacity, mucus plugging (MP), consolidations, linear densities (LD), and air trapping (AT). Each category was scored 0-2 in each of six lobar regions (with lingula separated from left upper lobe).Results: Absolute average overall scores of the controls and children with asthma were 0.72 ± 1.59 and 5.39 ± 5.83, respectively (P < 0.0001). Children with asthma scored significantly higher for BR (N = 20, 0.33 ± 0.80, P = 0.0002), BWT (N = 28, 0.72 ± 1.40, P < 0.0001), MP (N = 28, 0.37 ± 1.12, P = 0.0052), consolidation (N = 31, 0.67 ± 1.22, P < 0.0001), LD (N = 58, 1.12 ± 1.44, P < 0.0001), and AT (N = 52, 1.78 ± 2.31, P < 0.0001). There was a significant difference between the BR score of children with positive inflammatory response in BALF (N = 53) and those who were negative for airway inflammation cells (0.14 ± 0.36, P = 0.040).Conclusions: Significant lung structural abnormalities were readily identified on CT of children with asthma, with image differentiation of those with an inflammatory response on BALF. Chest imaging demonstrates potential as a noninvasive clinical tool for additional characterization of asthma phenotypes.

Focused CT for the evaluation of suspected appendicitis

PURPOSE

To determine the diagnostic accuracy of focused appendiceal CT as a feasible alternative to the standard CT of the abdomen and pelvis (CT-AP) in patients with suspected acute appendicitis.

METHODS

Retrospective review of 200 adults with suspected acute appendicitis between January and October 2016 were included in this study. Each patient underwent CT-AP with oral and intravenous (IV) contrast. A subset of axial images starting at the top of L4 vertebral body to the roof of the acetabula were obtained from each study which served as the focused appendiceal CT. After review of the focused CTs, the non-focused CT-AP scans were reviewed, each patient acting as their own control. Images were assessed for ability to identify the appendix, assess for appendicitis, or identify alternative diagnoses that could account for the presenting symptoms.

RESULTS

Of 200 cases, the appendix was visualized in the focused CT in 191 patients. In nine studies, the appendix was not visualized in focused or standard CT-AP. Using focused CT, 42 cases were positive for acute appendicitis. This result was identical when reviewing standard CT-AP. Alternative diagnoses were present in 38 patients. Using focused CT, 14 of these were not fully covered but the readers were able to make the diagnoses confidently on the focused CTs. Only one patient had acute non-appendiceal pathology mostly outside of the field of view.

CONCLUSIONS

Focused appendiceal CT with IV and oral contrast in the setting of clinically suspected appendicitis is a suitable alternative to conventional CT-AP.

Trends in advanced imaging and hospitalization for emergency department syncope care before and after ACEP clinical policy

OBJECTIVES

To describe recent trends in advanced imaging and hospitalization of emergency department (ED) syncope patients, both considered "low-value", and examine trend changes before and after the publication of American College Emergency Physician (ACEP) syncope guidelines in 2007, compared to conditions that had no changes in guideline recommendations.

METHODS

We analyzed 2002-2015 National Hospital Ambulatory Medical Care Survey data using an interrupted-time series with comparison series design. The primary outcomes were advanced imaging among ED visits with principal diagnosis of syncope and headache and hospitalization for ED visits with principal diagnosis of syncope, chest pain, dysrhythmia, and pneumonia. We adjusted annual imaging and hospitalization rates using survey-weighted multivariable logistic regression, controlling for demographic and visit characteristics. Using adjusted outcomes as datapoints, we compared linear trends and trend changes of annual imaging and hospitalization rates before and after 2007 with aggregate-level multivariable linear regression.

RESULTS

From 2002 to 2007, advanced imaging rates for syncope increased from 27.2% to 42.1% but had no significant trend after 2007 (trend change: -3.1%; 95%CI -4.7, -1.6). Hospitalization rates remained at approximately 37% from 2002 to 2007 but declined to 25.7% by 2015 (trend change: -2.2%; 95%CI -3.0, -1.4). Similar trend changes occurred among control conditions versus syncope, including advanced imaging for headache (difference in trend change: -0.6%; 95%CI -2.8, 1.6) and hospitalizations for chest pain, dysrhythmia, and pneumonia (differences in trend changes: 0.1% [95%CI -1.9, 2.0]; -0.9% [95%CI -3.1, 1.3]; and -1.2% [95%CI -5.3, 2.9], respectively).

CONCLUSIONS

Before and after the release of 2007 ACEP syncope guidelines, trends in advanced imaging and hospitalization for ED syncope visits had similar changes compared to control conditions. Changes in syncope care may, therefore, reflect broader practice shifts rather than a direct association with the 2007 ACEP guideline. Moreover, utilization of advanced imaging remains prevalent. To reduce low-value care, policymakers should augment society guidelines with additional policy changes such as reportable quality measures.

Concurrent lymphoma and hemophilia B in a pediatric patient: A case report

INTRODUCTION

Lymphoma is the third most common cancer among children in the United States and Europe. Hemophilia is a congenital bleeding disorder characterized by deficiency of coagulation factor VIII or IX. Hemophilia B is a consequence of factor IX deficiency and has an incidence of 1 in 20,000 male births. A concurrence of these 2 uncommon diseases is rare except in patients infected with the human immunodeficiency virus (HIV). We report a case of a patient with both Burkitt lymphoma and hemophilia B; this is only such report in China since 1987.

PATIENT CONCERNS

A 3-year-old boy was admitted to our hospital because of melena and jaundice for several days. His older brother had died due to hemophilia B and ventricular septal defect. The patient had not experienced any previous episodes of severe bleeding. Gradual abdominal distention was observed after admission; the patient's superficial lymph nodes were not enlarged. Results of blood routine and bone marrow examinations showed no abnormalities. He was diagnosed with sclerosing cholangitis, abdominal infection, and hepatitis. However, after treatment of reducing enzyme activity and eliminating jaundice, the patient's condition deteriorated. Hydrops abdominis was detected on abdominal ultrasonography. Tumor cells were found by pathological examination of peritoneal effusion. Both a c-myc gene translocation and a c-myc-IgH gene fusion were detected.

DIAGNOSIS

Burkitt lymphoma and hemophilia B.

INTERVENTIONS

The patient was transferred to the Pediatric Hematology Department of our hospital and treated with a modified B-NHL-BFM-95 protocol. During chemotherapy, platelet changes were monitored regularly and blood products were infused timely.

OUTCOMES

The patient died of infection and bleeding after chemotherapy.

CONCLUSION

Concurrent hemophilia and lymphoma are rare, especially in children. When encountering a patient with unexplained obstructive jaundice and massive ascites, the possibility of a tumor should be considered. Early diagnosis and adequate treatment of such tumor may improve prognosis.

Low-Dose CT With the Adaptive Statistical Iterative Reconstruction V Technique in Abdominal Organ Injury: Comparison With Routine-Dose CT With Filtered Back Projection

OBJECTIVE. The purpose of this study was to evaluate and compare the diagnostic performance and image quality of low-dose CT performed with adaptive statistical iterative reconstruction (ASIR)-V with those of routine-dose CT with filtered back projection (FBP) in the evaluation of abdominal organ injury. MATERIALS AND METHODS. The study enrolled 197 patients with trauma who underwent multiphase abdominal CT, including routine-dose portal venous phase imaging with FBP and low-dose delayed phase imaging with 50% ASIR-V. The presence of abdominal organ injuries (liver, spleen, pancreas, kidney) was reviewed, and injuries were graded according to American Association for the Surgery of Trauma (AAST) scales. CT detection rates of organ injury and AAST grading with the two protocols were compared by McNemar test. Subjective analysis of image noise and artifacts and objective analysis of CT noise were performed by unpaired t test. RESULTS. Compared with the routine-dose protocol, the low-dose protocol enabled an mean dose reduction of 59.8%. The detection rates and diagnostic performance of AAST grading did not differ significantly between the two protocols (detection rate, p = 0.289; diagnostic performance, p > 0.999). Objective image noise was significantly less with the low-dose protocol than with the routine-dose protocol (p < 0.001). Subjective imaging artifacts were similar between the low-dose and routine-dose protocols (p = 0.539). CONCLUSION. Compared with routine-dose protocol with FBP, low-dose CT with ASIR-V was useful for assessing multiorgan abdominal injury without impairing image quality.

Positive visualization of MR-compatible nitinol stent using a susceptibility-based imaging technique

Background

MR-compatible metallic stents have been widely used for the treatment of arterial occlusive diseases. However, conventional MR techniques have difficulty in accurately localizing the stent position and access the stent restenosis because of the susceptibility and radiofrequency (RF) shielding artifacts caused by the stent mesh. Previous studies have demonstrated that a susceptibility-based positive contrast MR method exhibits excellent efficacy for visualizing MR compatible metal devices. However, the method had not been evaluated in the visualization of stents and for the assessment of stent restenosis.

Methods

The susceptibility-based positive contrast MR method was used to visualize the nitinol stents and assess the stent restenosis by comparing two typical MR positive contrast techniques, i.e., susceptibility gradient mapping using the original resolution (SUMO) and the gradient echo acquisition for super-paramagnetic particles (GRASP) with positive contrast.

Results

Three sets of experiments were respectively performed to investigate the influence of stent orientation and spatial resolution on the susceptibility-based method, and to demonstrate the feasibility of the susceptibility-based method in evaluating the stent restenosis comparing to the two typical MR positive contrast methods, GRASP and SUMO.

Conclusions

The susceptibility-based method provides better visualization and localization of the stent than SUMO and GRASP and has the capability of assessing the stent restenosis.

Actual frequency of imaging during follow-up of testicular cancer in Israel-a comparison with the guidelines

OBJECTIVES

Computed tomography (CT) examinations are frequent in follow-up care of testicular cancer (TC) but may increase the risk for other cancers. We wanted to assess the actual number of CT and X-ray examinations within the first 5 years after a diagnosis of TC in Israel during 2003-2007.

METHODS

The database of Maccabi Healthcare Services, Israel, was searched for TC patients diagnosed in 2003 to 2007 by direct linkage with the Israel National Cancer Registry. Data on diagnostic imaging examinations (CT of chest, abdomen, or pelvis, unspecified sites; X-ray of chest) were extracted during a 5-year follow-up for 226 incident patients. The actual number of CT and X-ray examinations was compared to the National Comprehensive Cancer Network (NCCN) guideline. We tabulated the median with 10th and 90th percentiles (P10, P90) for the number of CTs and X-rays considering histology, stage, and adjuvant strategy.

RESULTS

The number of abdomen or pelvis CTs for TC patients receiving chemo- or radiotherapy was in accordance with the NCCN guideline. The median of abdomen or pelvis CTs for surveillance patients was 8.5 (P10, P90: 3; 13) for nonseminoma and 5.0 (P10, P90: 5; 13) for seminoma patients compared to 14 to 17 CTs recommended. The number of chest X-rays was lower than recommended in the guideline for all adjuvant strategies.

CONCLUSIONS

The NCCN guidelines regarding CTs were met for TC patients treated with chemo- or radiotherapy but fell below recommendations for surveillance. Guidelines from 2011 and 2012 were updated in favor of fewer CTs during surveillance.

KEY POINTS

• The number of CTs followed the NCCN guidelines in patients treated with chemo- or radiotherapy. • Surveillance patients received fewer CTs and X-rays than recommended in the NCCN guidelines from 2005. • The number of applied CT examinations corresponded to a radiation dose that did not substantially raise the lifetime risk for cancer.

Systematic review of diagnostic pathways for patients presenting with acute abdominal pain

Purpose

Abdominal pain is the most common reason for surgical referral. Imaging, aids early diagnosis and treatment. However unnecessary requests are associated with increased costs, radiation exposure and increased length of stay. Pathways can improve the quality of the diagnostic process. The aim of this systematic review was to identify the current evidence for diagnostic pathways and their use of imaging and effect on final outcomes.

Data sources

A systematic search of Embase, Medline and Cochrane databases was performed using keywords and MeSH terms for abdominal pain.

Study selection

All papers describing a pathway and published between January 2000 and January 2017 were included.

Data extraction

Data was obtained about the use of imaging, complications and length of stay. Quality assessment was performed using MINORS and Level of Evidence.

Results

Ten articles were included, each describing a different pathway. Five studies based the pathway on literature reviews alone and five studies on the results of their prospective study. Of the latter five studies, four showed that routine imaging increased diagnostic accuracy, but without showing a reduction in length of stay, complication rate or mortality. None of the studies included evaluated use of hospital resources or costs.

Conclusion

Pathways incorporating routine imaging will improve early diagnosis, but has not been proven to reduce complication rates or hospital length of stay. On the basis of this systematic review conclusions can therefore not be drawn about the pathways described and their benefit to the diagnostic process for patients presenting with abdominal pain.

Patient centring and scan length: how inaccurate practice impacts on radiation dose in CT colonography (CTC)

OBJECTIVE

The aim of this study was to acknowledge errors in patients positioning in CT colonography (CTC) and their effect in radiation exposure.

MATERIALS AND METHODS

CTC studies of a total of 199 patients coming from two different referral hospitals were retrospectively reviewed. Two parameters have been considered for the analysis: patient position in relation to gantry isocentre and scan length related to the area of interest. CTDI vol and DLP were extracted for each patient. In order to evaluate the estimated effective total dose and the dose to various organs, we used the CT-EXPO^® software version 2.2. This software provides estimates of effective dose and doses to the other various organs.

RESULTS

Average value of the patients' position is found to be below the isocentre for 48 ± 25 mm and 29 ± 27 mm in the prone and supine position. It was observed that the increase in CTDI and DLP values for patients in Group 1, due to the inaccurate positioning, was estimated at about 30% and 20% for prone and supine position, respectively, while in Group 2, a decrease in CTDI and DLP values was estimated at about 16% and 18% for prone and supine position, respectively, due to an average position above isocentre. A dose increase ranging from 4 up to 13% was calculated with increasing the over-scanned region below anal orifice.

CONCLUSION

Radiographers and radiologists need to be aware of dose variation and noise effects on vertical positioning and over-scanning. More accurate training need to be achieved even so when examination protocol varies from general practice.

Renal imaging in 199 Dutch patients with Birt-Hogg-Dubé syndrome: Screening compliance and outcome

Birt-Hogg-Dubé syndrome is associated with an increased risk for renal cell carcinoma. Surveillance is recommended, but the optimal imaging method and screening interval remain to be defined. The main aim of our study was to evaluate the outcomes of RCC surveillance to get insight in the safety of annual US in these patients. Surveillance data and medical records of 199 patients with Birt-Hogg-Dubé syndrome were collected retrospectively using medical files and a questionnaire. These patients were diagnosed in two Dutch hospitals and data were collected until June 2014. A first screening for renal cell carcinoma was performed in 172/199 patients (86%). Follow-up data were available from 121 patients. The mean follow-up period per patient was 4.2 years. Of the patients known to be under surveillance, 83% was screened at least annually and 94% at least every two years. Thirty-eight renal cell carcinomas had occurred in 23 patients. The mean age at diagnosis of the first tumour was 51. Eighteen tumours were visualized by ultrasound. Nine small tumours (7–27 mm) were visible on MRI or CT and not detected using ultrasound. Our data indicate that compliance to renal screening is relatively high. Furthermore, ultrasound might be a sensitive, cheap and widely available alternative for MRI or part of the MRIs for detecting clinically relevant renal tumours in BHD patients,but the limitations should be considered carefully. Data from larger cohorts are necessary to confirm these observations.

Interstitial lung abnormalities: erecting fences in the path towards advanced pulmonary fibrosis

Interstitial lung abnormalities, when present in members of undiagnosed family members recruited on the basis of familial interstitial pneumonia, or in undiagnosed research participants, have been associated with a syndrome that includes distinct sets of imaging abnormalities, restrictive physiological and exercise impairments, and an increased prevalence of histopathological findings, and genetic predictors, that have been noted in patients with idiopathic pulmonary fibrosis. Recent longitudinal studies have demonstrated that qualitative and quantitative assessments of interstitial abnormalities are associated with accelerated lung function decline, an increased rate of clinical diagnoses of interstitial lung disease and an increased rate of mortality. In this perspective, in addition to reviewing the prior information, four major efforts that could help the field of early pulmonary fibrosis detection move forward are discussed. These efforts include: (1) developing standards for characterising and reporting imaging findings from patients with existing CTs; (2) developing consensus statements on when undiagnosed and asymptomatic imaging abnormalities should be considered a disease; (3) identifying populations for which screening efforts might be beneficial; and (4) considering approaches to developing effective secondary prevention trials.

An open label, prospective, multicenter, non-interventional study of iodixanol 270 mg I/mL for use in individuals undergoing computed tomography angiography in real-world clinical practice

BACKGROUND

Concern about radiation exposure is leading to an increasing interest in low-concentration contrast medium administration.

PURPOSE

To evaluate the image quality and safety profile after administration of iodixanol 270 mg I/mL at 100-kVp tube voltage with iterative reconstruction in subjects undergoing computed tomography angiography (CTA).

MATERIAL AND METHODS

Patients who completed CTA examination using iodixanol 270 mg I/mL and 100-kVp tube voltage along with iterative reconstruction for coronary, aortic, head and neck, renal, or pulmonary arteries were included. Image quality was qualitatively and quantitatively evaluated. Incidence of adverse events (AEs) and adverse drug reactions (ADRs) within seven days and radiation dose were also analyzed.

RESULTS

A total of 4513 individuals in 42 centers in China were enrolled, among which 4367 were included in efficacy analysis. The mean image quality score was 4.8 ± 0.45 across all arteries (all above 4.6) and 99.7% of the individuals' images were classified as evaluable. The CT attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in the regions of interest (ROIs) were 431.79 ± 99.018, 18.29 ± 11.947, and 28.21 ± 19.535 HU, respectively. Of all the participants, 68 (1.5%) and 65 (1.4%) experienced AEs and ADRs, respectively. No serious AEs or AEs leading to discontinuation occurred. The average effective radiation dose was 3.13 ± 2.550 mSv.

CONCLUSION

Iodixanol 270 mg I/mL in combination with 100-kVp tube voltage and iterative reconstruction could be safely applied in CTA and yield high-quality and evaluable images with reduced radiation dose.

Knowledge-based iterative reconstructions for imaging of coronary artery stents: first in-vitro experience and comparison of different radiation dose levels and kernel settings

BACKGROUND

Advanced knowledge-based iterative model reconstructions (IMR) became recently available for routine computed tomography (CT). Using more realistic physical models it promises improved image quality and potential radiation dose reductions, both possibly beneficial for non-invasive assessment of coronary stents.

PURPOSE

To evaluate the influence of different IMR settings at different radiation doses on stent lumen visualization in comparison to filtered back projection (FBP) and first-generation (hybrid) iterative reconstruction (HIR).

MATERIAL AND METHODS

Ten coronary stents in a coronary phantom were examined at four different dose settings (120 kV/125 mAs, 120 kV/75 mAs, 100 kV/125 mAs, 100 kV/75 mAs). Images were reconstructed with stent-specific FBP and HIR kernels and with IMR using CardiacRoutine (CR) and CardiacSharp (CS) settings at three different iteration levels. Image quality was evaluated using established parameters: image noise; in-stent attenuation difference; and visible lumen diameter.

RESULTS

Image noise was significantly lower in IMR than in corresponding HIR and FBP images. At lower radiation doses, image noise increased significantly except with IMR CR3 and IMR CS3. Visible lumen diameters were significantly larger with IMR CS than with FBP, HIR, and IMR CR. IMR CR showed the smallest attenuation difference, while attenuation was artificially decreased extensively with IMR CS. FBP and HIR showed moderately increased in-stent attenuations. No relevant influence of used radiation doses on visible lumen diameters or attenuation differences was found.

CONCLUSION

IMR CR reduces image noise significantly while offering comparable stent-specific image quality in comparison to FBP and HIR and therefore potentially facilitates stent lumen delineation. Utilization of IMR CS for stent evaluation seems unfavorable due to artificial image alterations.

Implementation of Korean Clinical Imaging Guidelines: A Mobile App-Based Decision Support System

OBJECTIVE

The aims of this study were to develop a mobile app-based clinical decision support system (CDSS) for implementation of Korean clinical imaging guidelines (K-CIGs) and to assess future developments therein.

MATERIALS AND METHODS

K-CIGs were implemented in the form of a web-based application (http://cdss.or.kr/). The app containing K-CIGs consists of 53 information databases, including 10 medical subspecialties and 119 guidelines, developed by the Korean Society of Radiology (KSR) between 2015 and 2017. An email survey consisting of 18 questions on the implementation of K-CIGs and the mobile app-based CDSS was distributed to 43 members of the guideline working group (expert members of the KSR and Korean Academy of Oral and Maxillofacial Radiology) and 23 members of the consultant group (clinical experts belonging to related medical societies) to gauge opinion on the future developmental direction of K-CIGs.

RESULTS

The web-based mobile app can be downloaded from the Google Play Store. Detailed information on the grade of recommendation, evidence level, and radiation dose for each imaging modality in the K-CIGs can be accessed via the home page and side menus. In total, 32 of the 66 experts contacted completed the survey (response rate, 45%). Twenty-four of the 32 respondents were from the working group and eight were from the consulting group. Most (93.8%) of the respondents agreed on the need for ongoing development and implementation of K-CIGs.

CONCLUSION

This study describes the mobile app-based CDSS designed for implementation of K-CIGs in Korea. The results will allow physicians to have easy access to the K-CIGs and encourage appropriate use of imaging modalities.

High-pitch, 120 kVp/30 mAs, low-dose dual-source chest CT with iterative reconstruction: Prospective evaluation of radiation dose reduction and image quality compared with those of standard-pitch low-dose chest CT in healthy adult volunteers

PURPOSE

Objective of this study was to evaluate the effectiveness of the iterative reconstruction of high-pitch dual-source chest CT (IR-HP-CT) scanned with low radiation exposure compared with low dose chest CT (LDCT).

MATERIALS AND METHODS

This study was approved by the institutional review board. Thirty healthy adult volunteers (mean age 44 years) were enrolled in this study. All volunteers underwent both IR-HP-CT and LDCT. IR-HP-CT was scanned with 120 kVp tube voltage, 30 mAs tube current and pitch 3.2 and reconstructed with sinogram affirmed iterative reconstruction. LDCT was scanned with 120 kVp tube voltage, 40 mAs tube current and pitch 0.8 and reconstructed with B50 filtered back projection. Image noise, and signal to noise ratio (SNR) of the infraspinatus muscle, subcutaneous fat and lung parenchyma were calculated. Cardiac motion artifact, overall image quality and artifacts was rated by two blinded readers using 4-point scale. The dose-length product (DLP) (mGy∙cm) were obtained from each CT dosimetry table. Scan length was calculated from the DLP results. The DLP parameter was a metric of radiation output, not of patient dose. Size-specific dose estimation (SSDE, mGy) was calculated using the sum of the anteroposterior and lateral dimensions and effective radiation dose (ED, mSv) were calculated using CT dosimetry index.

RESULTS

Approximately, mean 40% of SSDE (2.1 ± 0.2 mGy vs. 3.5 ± 0.3 mGy) and 34% of ED (1.0 ± 0.1 mSv vs. 1.5 ± 0.1 mSv) was reduced in IR-HP-CT compared to LDCT (P < 0.0001). Image noise was reduced in the IR-HP-CT (16.8 ± 2.8 vs. 19.8 ± 3.4, P = 0.0001). SNR of lung and aorta of IR-HP-CT showed better results compared with that of LDCT (22.2 ± 5.9 vs. 33.0 ± 7.8, 1.9 ± 0.4 vs 1.1 ± 0.3, P < 0.0001). The score of cardiac pulsation artifacts were significantly reduced on IR-HP-CT (3.8 ± 0.4, 95% confidence interval, 3.7‒4.0) compared with LDCT (1.6 ± 0.6, 95% confidence interval, 1.3‒1.8) (P < 0.0001). SNR of muscle and fat, beam hardening artifact and overall subjective image quality of the mediastinum, lung and chest wall were comparable on both scans (P ≥ 0.05).

CONCLUSION

IR-HP-CT with 120 kVp and 30 mAs tube setting in addition to an iterative reconstruction reduced cardiac motion artifact and radiation exposure while representing similar image quality compared with LDCT.

Evaluating the Prognosis of Ischemic Stroke Using Low-Dose Multimodal Computed Tomography Parameters in Hyperacute Phase

PURPOSE

The aim of this study was to evaluate the potential value of low-dose multimodal computed tomography (CT) in predicting prognosis of acute ischemic stroke (AIS) within 6 hours.

METHODS

The admission "one-stop-shop" multimodal CT examination, including noncontrast CT (NCCT), low-dose CT perfusion, and CT angiography (CTA), was performed in patients with symptoms of stroke within 6 hours. Noncontrast CT, CTA source image (CTA-SI), cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), and mean transit time (MTT) maps were studied using Alberta Stroke Program Early CT Score (ASPECTS). The regional leptomeningeal collateral (rLMC) score (0-20) was dichotomized into 2 groups: good (11-20) and poor (0-10) rLMC. Poor functional outcomes were defined by a modified Rankin scale score of 3 to 6.

RESULTS

One hundred forty-four patients were ultimately selected; 43.8% of them showed poor functional outcomes. They had lower ASPECTSs on NCCT, CTA-SI, CBV, CBF, TTP, and MTT, and poor rLMC was more frequently associated with poor functional outcomes (all P < 0.001). In the multivariate analysis for AIS patients with conservative treatment, CTA-SI-ASPECTS 6 or less (odds ratio [OR], 5.9; 95% confidence interval [95% CI], 1.9-18.4; P = 0.002) and poor collaterals (OR, 5.0; 95% CI, 1.3-15.4; P = 0.017), CBV-ASPECTS 6 or less (OR, 8.0; 95% CI, 2.7-24.0; P < 0.001), CBF-ASPECTS 4 or less (OR, 8.0; 95% CI, 2.0-31.5; P = 0.003), MTT-ASPECTS≤3 (OR, 5.8; 95% CI, 1.8-18.1; P = 0.003), TTP-ASPECTS 4 or less (OR, 5.0; 95% CI, 1.6-15.1; P = 0.005), and NCCT-ASPECTS 8 or less (OR, 5.9; 95% CI, 1.7-20.4; P = 0.005) were significantly associated with poor functional outcome. In the multivariate analysis for AIS patients with thrombolysis, CTA-SI-ASPECTS 6 or less (OR, 27.5; 95% CI, 2.9-262.3; P = 0.004), poor collaterals (OR, 28.0; 95% CI, 2.8-283.0; P < 0.028), and CBV-ASPECTS 6 or less (OR, 18.0; 95% CI, 3.0-107.7; P = 0.002) were associated with poor functional outcomes. Furthermore, the area under the curve (AUC) of the combination of CTA-SI-ASPECTS 6 or less, poor collaterals, and CBV-ASPECTS 6 or less (AUC, 0.87) was greater than that for any single parameter alone: CTA-SI-ASPECTS 6 or less (AUC, 0.80; P < 0.001), poor collaterals (AUC, 0.76; P < 0.001), and CBV-ASPECTS 6 or less (AUC, 0.81; P = 0.002).

CONCLUSIONS

The combination of CTA-SI-ASPECTS, collaterals, and CBV-ASPECTS may improve predictive power compared with a single parameter alone.

Sickle cell disease and venous thromboembolism: A retrospective comparison of the rate of positive CT pulmonary angiography in the emergency department

BACKGROUND

Previous authors have reported an increased incidence of acute pulmonary embolism (PE) in patients with sickle cell disease (SCD) based on retrospective analysis of ICD codes. It is unknown whether patients with SCD have higher rates of positive CT pulmonary angiogram (CTPA) in the emergency department (ED).

METHODS

The institutional review board (IRB) approved this retrospective study; informed consent was waived. Between January 1, 2005 and May 31, 2015, 28 patients with SCD underwent a total of 78 CTPA studies in the ED. A control group of 75 non-SCD patients matched for age, gender and race underwent 78 consecutive CTPA studies in the emergency department. Modified Wells' (mWells') scores were calculated for each CTPA study performed. The studies for both groups were blind read by two fellowship trained body radiologists. Descriptive statistics were performed, with significance considered if p < 0.05.

RESULTS

The rate of positive CT pulmonary angiogram in patients with SCD was 6.4% (5/78), compared with 12.8% (10/78) in non-SCD matched controls. There was no significant difference in the rate of positive CTPA (p = 0.277). There was also no difference in the mean mWells' score between the two groups (2.44 for SCD vs. 1.95 for controls, p = 0.120).

CONCLUSION

SCD patients did not have a significantly different rate of acute PE when compared with matched controls undergoing CTPA in the ED.

Head-to-head comparison of adaptive statistical and model-based iterative reconstruction algorithms for submillisievert coronary CT angiography

Aims

Iterative reconstruction (IR) algorithms allow for a significant reduction in radiation dose of coronary computed tomography angiography (CCTA). We performed a head-to-head comparison of adaptive statistical IR (ASiR) and model-based IR (MBIR) algorithms to assess their impact on quantitative image parameters and diagnostic accuracy for submillisievert CCTA.

Methods and results

CCTA datasets of 91 patients were reconstructed using filtered back projection (FBP), increasing contributions of ASiR (20, 40, 60, 80, and 100%), and MBIR. Signal and noise were measured in the aortic root to calculate signal-to-noise ratio (SNR). In a subgroup of 36 patients, diagnostic accuracy of ASiR 40%, ASiR 100%, and MBIR for diagnosis of coronary artery disease (CAD) was compared with invasive coronary angiography. Median radiation dose was 0.21 mSv for CCTA. While increasing levels of ASiR gradually reduced image noise compared with FBP (up to - 48%, P < 0.001), MBIR provided largest noise reduction (-79% compared with FBP) outperforming ASiR (-59% compared with ASiR 100%; P < 0.001). Increased noise and lower SNR with ASiR 40% and ASiR 100% resulted in substantially lower diagnostic accuracy to detect CAD as diagnosed by invasive coronary angiography compared with MBIR: sensitivity and specificity were 100 and 37%, 100 and 57%, and 100 and 74% for ASiR 40%, ASiR 100%, and MBIR, respectively.

Conclusion

MBIR offers substantial noise reduction with increased SNR, paving the way for implementation of submillisievert CCTA protocols in clinical routine. In contrast, inferior noise reduction by ASiR negatively affects diagnostic accuracy of submillisievert CCTA for CAD detection.

CARE Dose 4D combined with sinogram-affirmed iterative reconstruction improved the image quality and reduced the radiation dose in low dose CT of the small intestine

OBJECTIVE

Multislice computed tomography (MSCT) has been used for diagnosis of small intestinal diseases. However, the radiation dose is a big problem. This study was to investigate whether CARE Dose 4D combined with sinogram-affirmed iterative reconstruction (SAFIRE) can provide better image quality at a lower dose for imaging small intestinal diseases compared to MSCT.

METHODS

The noise reduction ability of SAFIRE was assessed by scanning the plain water mold using SOMATOM Definition Flash double-source spiral CT. CT images at each stage of radiography for 239 patients were obtained. The patients were divided into groups A and B were based on different tube voltage and current or the image recombination methods. The images were restructured using with filtered back projection (FBP) and SAFIRE (S1-S5). The contrast noise ratio (CNR), CT Dose index (CTDI), subjective scoring, and objective scoring were compared to obtain the best image and reformation parameters at different stages of CT.

RESULTS

Twenty-six restructuring patterns of tube voltage and current were obtained by FBP and SAFIRE. The average radiation dose using CARE Dose 4D combined with SAFIRE (S4-S5) reduced approximately 74.85% compared to conditions where the tube voltage of 100 kV and tube current of 131 mAs for patients with MSCT small intestinal CT enterography at plain CT scan, arterial stage, small intestine, and portal venous phase. The objective and subjective scoring were all significantly different among groups A and B at each stage.

CONCLUSIONS

Combination of CARE Dose 4D and SAFIRE is shown to decrease the radiation dose while maintaining image quality.

Projection data smoothing through noise-level weighted total variation regularization for low-dose computed tomography

Reducing radiation dose while maintaining the quality of the reconstructed images is a major challenge in the computed tomography (CT) community. In light of the non-stationary Gaussian noise distribution, we developed a model that incorporates a noise-level weighted total variation (NWTV) regularization term for denoising the projection data. Contrary to the well-known edge-weighted total variation method, which aims for better edge preserving, the proposed NWTV tries to adapt the regularization with the spatially varying noise levels. Experiments on simulated data as well as the real imaging data suggest that the proposed NWTV regularization could achieve quite competitive results. For sinograms with sharp edges, the NWTV could do a better job at balancing noise reduction and edge preserving, such that noise is removed in a more uniform manner. Another conclusion from our experiments is that the well-recognized stair-casing artifacts of TV regularization play little role in the reconstructed images when the NWTV method is applied to low-dose CT imaging data.

Assessment of radiation dose and iodine load reduction in head-neck CT angiography using two scan protocols with wide-detector

OBJECTIVE

To compare image quality, radiation dose, and iodine intake of head-neck CT angiography (CTA) acquired by wide-detector with the gemstone spectral imaging (GSI) combination with low iodine intake or routine scan protocol.

METHODS

Three hundred patients who had head-neck CTA were enrolled and divided into three groups according to their BMI values: group A (18.5 kg/m2 ≦ BMI <24.9 kg/m2), group B (24.9 kg/m2 ≦ BMI <29.9 kg/m2) and group C (29.9 kg/m2 ≦ BMI ≦ 34.9 kg/m2) with 100 patients in each group. Patients in each group were randomly divided into two subgroups (n = 50) namely, A1, A2, B1, B2, C1 and C2. The patients in subgroups A1, B1 and C1 underwent GSI with low iodine intake (270 mgI/ml, 50 ml) and combined with the ASiR-V algorithm. Other patients underwent three dimensional (3D) smart mA modulation with routine iodine intake (350 mgI/ml, 60 ml). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of all images were calculated after angiography. Images were then subjectively assessed using a 5-point scale. CT dose index of volume and dose-length product (DLP) was converted to the effective dose (ED) and then compared.

RESULTS

The mean CT values, SNR, CNR and subjective image quality in subgroups A2, B2 and C2 are significantly lower than in subgroups A1, B1, and C1 (P < 0.01), respectively. The ED values in subgroup A1, B1, and C1 are 55.18%, 61.89%, and 69.64% lower than those in A2, B2, and C2, respectively (P < 0.01). The total iodine intakes in subgroups A1, B1, and C1 are 35.72% lower than those in subgroups A2, B2, and C2.

CONCLUSIONS

The gemstone spectral imaging with monochromatic images at 53-57 keV combined with ASiR-V algorithm allows significant reduction in iodine load and radiation dose in head-neck CT angiography than those yielded in routine scan protocol. It also enhances signal intensity of head-neck CTA and maintains image quality.

Risk of Radiation-Induced Cancer From Computed Tomography Angiography Use in Imaging Surveillance for Unruptured Cerebral Aneurysms

Background and Purpose- Although computed tomography angiography (CTA) is an excellent, noninvasive imaging modality for surveillance of intracranial aneurysms, radiation concerns have been cited to restrict its use in surveillance imaging. The goal of this study was to estimate distributions of radiation-induced central nervous system cancer incidence from CTA surveillance for intracranial aneurysms, and the impact of frequency and duration of surveillance imaging using follow-up CTAs. Methods- Simulation-modeling approach was performed using data on CTA associated radiation risk. We used the Radiation Risk Assessment Tool, based on the data using the BEIR VII report (BEIR VII). Each CTA was assigned as a separate exposure event. Men and women, respectively, starting surveillance imaging at 30, 40, and 50 years and receiving annual CTAs were considered as separate subgroups. As a comparison, we also calculated the radiation-induced cancer risk in the same groups of patients but receiving CTAs every 2 and 5 years, respectively. Results- CTA-associated excess cancer risk per exposure increases relatively more rapidly with the first 10 exposures and plateaus after the 44th exposure. On average, per CTA incurs ≈0.0026% in excess lifetime cancer risk. Receiving CTA follow-up at a younger age, more frequent follow-up, longer surveillance period, and men are the major factors contributing to an elevated excess lifetime risk. In the highest risk group, male patient receiving annual CTA follow-ups from the age of 30 years, the excess lifetime risk is 0.115% at the age of 81 years. Conclusions- Radiation-induced brain cancer incidence associated with unruptured intracranial aneurysm surveillance strategies using CTA is low relative to the risk for aneurysmal rupture. Further cost-effectiveness/utility analyses might help assess this risk in the context of aneurysmal ruptures prevented by surveillance imaging.

Can MRI contribute to pulmonary nodule analysis?

BACKGROUND

There is no accurate method distinguishing different types of pulmonary nodules.

PURPOSE

To investigate whether multiparametric 3T MRI biomarkers can distinguish malignant from benign pulmonary nodules, differentiate different types of neoplasms, and compare MRI-derived measurements with values from commonly used noninvasive imaging modalities.

STUDY TYPE

Prospective.

SUBJECTS

Sixty-eight adults with pulmonary nodules undergoing resection.

SEQUENCES

Respiratory triggered diffusion-weighted imaging (DWI), periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) fat saturated T₂ -weighted imaging, T₁ -weighted 3D volumetric interpolated breath-hold examination (VIBE) using CAIPIRINHA (controlled aliasing in parallel imaging results in a higher acceleration).

ASSESSMENT/STATISTICS

Apparent diffusion coefficient (ADC), T₁ , T₂ , T₁ and T₂ normalized to muscle (T₁ /M and T₂ /M), and dynamic contrast enhancement (DCE) values were compared with histology to determine whether they could distinguish malignant from benign nodules and discern primary from secondary malignancies using logistic regression. Predictability of primary neoplasm types was assessed using two-sample t-tests. MRI values were compared with positron emission tomography / computed tomography (PET/CT) to examine if they correlated with standardized uptake value (SUV) or CT Hounsfield unit (HU). Intra- and interreader agreements were assessed using intraclass correlations.

RESULTS

Forty-nine of 74 nodules were malignant. There was a significant association between ADC and malignancy (odds ratio 4.47, P < 0.05). ADC ≥1.3 μm² /ms predicted malignancy. ADC, T₁ , and T₂ together predicted malignancy (P = 0.003). No MRI parameter distinguished primary from metastatic neoplasms. T₂ predicted PET positivity (P = 0.016). T₂ and T₁ /M correlated with SUV (P < 0.05). Of 18 PET-negative malignant nodules, 12 (67%) had an ADC ≥1.3 μm² /ms. With the exception of T₂ , all noncontrast MRI parameters distinguished adenocarcinomas from carcinoid tumors (P < 0.05). T₁ , T₂ , T₁ /M, and T₂ /M correlated with HU and therefore can predict nodule density. Combined with ADC, washout enhancement, arrival time (AT), peak enhancement intensity (PEI), K^trans , K_ep , V_e collectively were predictive of malignancy (P = 0.012). Combined washin, washout, time to peak (TTP), AT, and PEI values predicted malignancy (P = 0.043). There was good observer agreement for most noncontrast MRI biomarkers.

DATA CONCLUSION

MRI can contribute to pulmonary nodule analysis. Multiparametric MRI might be better than individual MRI biomarkers in pulmonary nodule risk stratification.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

Long-Term Surveillance of Complex Cystic Renal Masses and Heterogeneity of Bosniak 3 Lesions

PURPOSE

We sought to better characterize the frequency of Bosniak cyst class changes, identify predictors of change and progression, determine the average growth rate of cysts and validate the safety of active surveillance.

MATERIALS AND METHODS

Consecutive patients referred for the management of complex cysts (Bosniak 2F or greater) were included in analysis. All imaging studies were reevaluated and any stage change was reviewed with a blinded genitourinary radiologist. Bosniak 3 cysts were subclassified as 3s-septated enhancing Bosniak cysts and 3n-cysts with wall or septation-only nodularity. A multivariate Cox proportional hazards model was used to identify predictors of the Bosniak classification change. Kaplan-Meier curves were applied to analyze Bosniak cyst progression and regression.

RESULTS

A total 140 lesions were included in study, necessitating review of a total of 1,011 abdominal scans in 111 patients. Median followup was 46 months (IQR 23-65.5) and patients underwent a mean of 6.8 diagnostic scans. On multivariate analysis nodular cysts progressed (HR 6.16, 95% CI 2.58-14.72, p <0.00004) and entirely endophytic cysts were less likely to progress (HR 0.21, 95% CI 0.05-0.85, p = 0.028). On Kaplan-Meier analysis Bosniak 3s cysts were more likely to regress while Bosniak 3n cysts were more likely to progress than 3s cysts (p = 0.0178 and 0.0002, respectively). The growth rate of 3n and 2F cysts was 0.19 and 0.11 cm per year (p = 0.0493 and 0.0327, respectively). Locally advanced or metastatic disease did not develop in any patient.

CONCLUSIONS

A diagnostic change in Bosniak 3s and 2F cysts is common and Bosniak 3n cysts behave more like Bosniak 4 cysts. Most complex kidney cysts can be safely monitored without intervention and the interval between serial imaging procedures should be increased.

Fibrous dysplasia for radiologists: beyond ground glass bone matrix

Fibrous dysplasia (FD) is a congenital disorder arising from sporadic mutation of the α-subunit of the Gs stimulatory protein. Osseous changes are characterised by the replacement and distortion of normal bone with poorly organised, structurally unsound, fibrous tissue. The disease process may be localised to a single or multiple bones. In McCune-Albright syndrome (MAS), fibrous dysplasia is associated with hyperfunction of endocrine organs and overproduction of melanin in the skin, while Mazabraud syndrome FD is associated with intramuscular myxomas. In radiology, FD is very often automatically associated with the term "ground glass matrix". However, FD is a complex disease, and knowledge of its unique pathogenesis and course are crucial to understanding imaging findings and potential complications. This article aims to not only summarise the spectrum of radiological findings of osseous and extra-osseous abnormalities associated with FD but also to highlight the pathological base of the disease evolution, corresponding imaging changes and complications based on the disease distribution. We also have provided current recommendations for clinical management and follow-up of patients with FD. TEACHING POINTS: • FD is often a part of complex disease, involving not only bone but also multiple other organs. • FD lesions are characterised by age-related histological, radiographical and clinical transformations. • Radiologists play a crucial role in the identification of osseous complications associated with FD. • The craniofacial form of the disease is the most common type of FD and the most difficult form to manage. • Patients with McCune-Albright syndrome may have different extra-skeletal abnormalities, which often require follow-up.

Subtle excess in lifetime cancer risk related to CT scanning in Spanish young people

BACKGROUND

CT scan is a life-saving medical diagnostic tool, entailing higher levels of ionising radiation exposure than conventional radiography, which may result in an increase in cancer risk, particularly in children. Information about the use and potential health effects of CT scan imaging among young people in Spain is scarce.

OBJECTIVE

This paper aims to estimate the number of radiation-related cancer cases which can be expected due to the use of CT scanning in Spanish children and young adults in a single year (2013).

METHODS

The 2013 distribution of number and types of CT scans performed in young people was obtained for Catalonia and extrapolated to the whole Spain. Organ doses were estimated based on the technical characteristics of 17,406 CT examinations extracted from radiology records. Age and sex-specific data on cancer incidence and life tables were obtained for the Spanish population. Age and sex-specific risk models developed by the Committee on Health Risks of Exposure to Low Levels of Ionizing Radiations (BEIR VII) and Berrington de Gonzalez were used, together, with the dose estimates to derive the lifetime attributable risks of cancer in Spain due to one year of CT scanning and project the number of future cancer cases to be expected.

RESULTS

In 2013, 105,802 CT scans were estimated to have been performed in people younger than age 21. It was estimated that a total of 168.6 cancer cases (95% CrI: 30.1-421.1) will arise over life due to the ionising radiation exposure received during these CTs. Lifetime attributable risks per 100,000 exposed patients were highest for breast and lung cancer. The largest proportion of CTs was to the head and neck and hence the highest numbers of projected cancer cases were of thyroid and oral cavity/pharynx.

CONCLUSIONS

Despite the undeniable medical effectiveness of CT scans, this risk assessment suggests a small excess in cancer cases which underlines the need for justification and optimisation in paediatric scanning. Given the intrinsic uncertainties of these risk projection exercises, care should be taken when interpreting the predicted risks.

External validation of the Scandinavian guidelines for management of minimal, mild and moderate head injuries in children

BACKGROUND

Clinical decision rules (CDRs) aid in the management of children with traumatic brain injury (TBI). Recently, the Scandinavian Neurotrauma Committee (SNC) has published practical, evidence-based guidelines for children with Glasgow Coma Scale (GCS) scores of 9-15. This study aims to validate these guidelines and to compare them with other CDRs.

METHODS

A large prospective cohort of children (< 18 years) with TBI of all severities, from ten Australian and New Zealand hospitals, was used to assess the SNC guidelines. Firstly, a validation study was performed according to the inclusion and exclusion criteria of the SNC guideline. Secondly, we compared the accuracy of SNC, CATCH, CHALICE and PECARN CDRs in patients with GCS 13-15 only. Diagnostic accuracy was calculated for outcome measures of need for neurosurgery, clinically important TBI (ciTBI) and brain injury on CT.

RESULTS

The SNC guideline could be applied to 19,007/20,137 of patients (94.4%) in the validation process. The frequency of ciTBI decreased significantly with stratification by decreasing risk according to the SNC guideline. Sensitivities for the detection of neurosurgery, ciTBI and brain injury on CT were 100.0% (95% CI 89.1-100.0; 32/32), 97.8% (94.5-99.4; 179/183) and 95% (95% CI 91.6-97.2; 262/276), respectively, with a CT/admission rate of 42% (mandatory CT rate of 5%, 18% CT or admission and 19% only admission). Four patients with ciTBI were missed; none needed specific intervention. In the homogenous comparison cohort of 18,913 children, the SNC guideline performed similar to the PECARN CDR, when compared with the other CDRs.

CONCLUSION

The SNC guideline showed a high accuracy in a large external validation cohort and compares well with published CDRs for the management of paediatric TBI.

Reduction of X-ray-induced DNA damage in normal human cells treated with the PrC-210 radioprotector

The aim of our study was to determine the protective efficacy of the PrC-210 aminothiol radioprotector against X-ray-induced DNA damage in normal human cells and to establish dose- and time-effect models for future PrC-210 use in humans. The PrC-210 structure has a branched structure which enables scavenging of reactive oxygen species (ROS) away from DNA. Normal human blood lymphocytes, fibroblasts and naked genomic DNA were exposed to PrC-210 seconds to hours prior to irradiation. Biological (γ-H2AX foci), chemical (8-oxo-deoxyguanosine) and physical (genomic DNA electrophoretic migration) DNA damage endpoints were scored to determine the ability of PrC-210 to suppress radiation-induced DNA damage. X-ray-induced γ-H2AX foci in blood lymphocytes were reduced by 80% after irradiation with 10, 50 and 100 mGy, and DNA double-strand breaks in fibroblasts were reduced by 60% after irradiation with 20 Gy. Additionally, we observed a reduction of 8-oxo-deoxyguanosine (an ROS-mediated, DNA damage marker) in human genomic DNA to background in a PrC-210 dose-dependent manner. PrC-210 also eliminated radiation-induced cell death in colony formation assays after irradiation with 1 Gy. The protective efficacy of PrC-210 in each of these assay systems supports its development as a radioprotector for humans in multiple radiation exposure settings.

Summary: A new strategy is decribed, using a new radioprotector (PrC-210) to significantly reduce radiation-induced DNA damage.

CNN as model observer in a liver lesion detection task for x-ray computed tomography: A phantom study

PURPOSE

The purpose of this study was the evaluation of anthropomorphic model observers trained with neural networks for the prediction of a human observer's performance.

METHODS

To simulate liver lesions, a phantom with contrast targets (acrylic spheres, varying diameters, +30 HU) was repeatedly scanned on a computed tomography scanner. Image data labeled with confidence ratings assessed in a reader study for a detection task of liver lesions were used to build several anthropomorphic model observers. Models were trained with images reconstructed with iterative reconstruction and evaluated with images reconstructed with filtered backprojection. A neural network, based on softmax regression (SR-MO), and convolutional neural networks (CNN-MO) were used to predict the performance of a human observer and compared to a channelized Hotelling observer [with Gabor channels and internal channel noise (CHOi)]. Model observers were evaluated by a receiver operating characteristic curve analysis and compared to the results in the reader study. Two strategies were used to train the SR-MO and CNN-MO: A) building a separate model for each lesion size; B) building one model that was applied to lesions of all sizes.

RESULTS

All tested model observers and the human observer were highly correlated at each lesion size and dose level. With strategy A, Pearson's product-moment correlation coefficients r were 0.926 (95% confidence interval (CI): 0.679-0.985) for SR-MO and 0.979 (95% CI: 0.902-0.996) for CNN-MO. With strategy B, r was 0.860 (95% CI: 0.454-0.970) for SR-MO and 0.918 (95% CI: 0.651-0.983) for CNN-MO. For CHOi, r was 0.945 (95% CI: 0.755-0.989). With strategy A, mean absolute percentage differences (MAPD) between the model observers and the human observer were 3.7% for SR-MO and 1.2% for CNN-MO. With strategy B, MAPD were 3.7% for SR-MO and 3.0% for CNN-MO. For the CHOi the MAPD was 2.2%.

CONCLUSION

Convolutional neural network model observers can accurately predict the performance of a human observer for all lesion sizes and dose levels in the evaluated signal detection task.

Craniocervical computed tomography angiography with adaptive iterative dose reduction 3D algorithm and automatic tube current modulation in patients with different body mass indexes

The aim of this study was to investigate the feasibility of head and neck computed tomography angiography (CTA) using the 80-kV tube voltage and the adaptive iterative dose reduction (AIDR) 3D algorithm in patients with different body mass indexes (BMIs).From November 2016 to January 2017, 128 consecutive patients scheduled for head and neck CTA examinations were randomized into the 100-kV group (n = 60) and the 80-kV group (n = 68). Both groups used the automatic tube current modulation technique and the AIDR 3D algorithm. The patients were further grouped as slender (BMI < 22 kg/m), normal weight (22 kg/m≤BMI < 25 kg/m), and overweight (BMI ≥25 kg/m). The image quality and the radiation dose of each subgroup were analyzed.The images of the head and neck vessels and the brain tissue obtained with 100 kV were all of diagnostic quality. Slender and normal weight patients imaged with 80 kV also produced images of diagnostic quality. However, 80 kV in the overweight patients failed to produce images of diagnostic quality. The radiation dose in the patients imaged with 80 kV was significantly decreased in comparison with those imaged with 100 kV. The effective dose was 0.36 ± 0.06 and 0.41 ± 0.05 mSv in the slender and normal weight patients imaged with 80 kV.Head and neck CTA scanning with 80 kV, automatic tube current modulation, and AIDR 3D algorithm can produce high quality images with reduced radiation dose in slender or normal weight patients.

Establishment of national diagnostic reference levels (DRLs) for radiotherapy localisation computer tomography of the head and neck

AIM

The aim of this research is to establish if variation exists in the dose delivered for head and neck (HN) localisation computed tomography (CT) imaging in radiation therapy (RT); to propose a national diagnostic reference levels (DRLs) for this procedure and to make a comparison between the national DRL and a DRL of a European sample.

BACKGROUND

CT has become an indispensable tool in radiotherapy (RT) treatment planning. It is a requirement of legislation in many countries that doses of ionising radiation for medical exposures be kept 'As Low As Reasonably Achievable'. There are currently no dose guidelines for RT localisation CT of the HN.

MATERIALS AND METHODS

All RT departments in Ireland and a sample of European departments were surveyed. Dose data on CT dose length product (DLP); dose index volume (CTDIvol); current time product; tube voltage and scan length was acquired for ten average-sized HN patients from each department. DRLs were proposed for DLP and CTDIvol using the rounded 75th percentile of the distribution of the means.

RESULTS

42% of Irish departments and one European department completed the survey. Significant variation was found in the mean DLP, CTDIvol and scan lengths across the Irish departments. The proposed Irish DRL is 882 mGy cm and 21 mGy and the European department DRL is 816 mGy cm and 21 mGy, for DLP and CTDIvol, respectively.

CONCLUSIONS

Variation exists in doses used for HN RT localisation CT. DRLs have been proposed for comparison purposes with the aim of dose optimisation.

Additional and repeated computed tomography in interfacility trauma transfers: Room for standardization

BACKGROUND

Despite the recommendations of the Advanced Trauma Life Support course of the American College of Surgeons, patients undergo computed tomography (CT) in local hospitals before transfer to a trauma center. The problem of repeat CTs caused by technical and protocol issues is ongoing. The objective is to measure the importance of repeat CTs and CTs involving other body regions.

METHODS

All secondary transfers to our level 1 facility with CT at the local hospital over 9 years were reviewed. Patients were considered to have had a repeat CT if the same body region or an another body region was scanned as a part of the initial assessment but not for reasons of clinical follow-up.

RESULTS

Of 6,292 patients received from local hospitals, 685 (12%) had undergone 1097 CT scans at the local hospitals. Patients being scanned in local hospitals were sicker (injury severity score: 21 vs 13) and required more intensive care unit admissions (38% vs 29%) and more ventilation (32% vs 22%). Thirty-nine percent of CTs were repeated, and 55% of these patients required imaging of another body part.

CONCLUSION

Repeat and additional images remain a major issue in trauma transfers. Improvement requires standardization of CT protocols and change in the approach of local hospitals from "finding and requiring need level 1 trauma center" to "not missing any injuries."

Role of FDG PET-CT in the treatment management of Hodgkin lymphoma

Fluorodeoxyglucose (FDG) positons emission tomography (PET)-computed tomography (CT) is used in many ways at baseline and during the treatment of patients with Hodgkin lymphoma. Many properties of the technique are used in the different steps of patient's management. Initial staging with PET-CT is more accurate than conventional imaging and PET-CT also became the gold standard imaging at the end of treatment with a negative PET-CT mandatory for reaching a complete remission. Early assessment of response by PET-CT is one of the most powerful prognostic factors for progression-free survival of patients with localized and advanced stages and allows guiding treatment. Conversely, previous studies showed that there is no role of FDG PET-CT for the patient's follow-up.

Knowledge-based iterative model reconstruction: Comparative image quality with low tube voltage cerebral CT angiography

The aim of this study was to compare image quality of low tube voltage cerebral computed tomography angiography (CTA) reconstructed with knowledge-based iterative model reconstruction (IMR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR).A total of 101 patients with suspected cerebrovascular diseases were enrolled and randomized into 2 groups, 100 kVp tube voltage (n = 53) and reduced tube voltage (80 kVp) (n = 48). Computed tomography data were reconstructed with IMR, FBP, and HIR algorithms. The image noise, vascular attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured and calculated. Two blinded radiologists independently evaluated image quality based on diagnostic confidence on a 3-point scale. Quantitative and qualitative assessments were compared between different groups and reconstruction subgroups.Vascular attenuation was higher in the reduced tube voltage group than in 100-kVp tube voltage group, but showed no significant difference within each group. In both groups, the image noise, vascular SNR, and CNR were significantly improved by IMR as compared with FBP and HIR. Inter-group comparison indicated that IMR with reduced tube voltage showed better image quality with lower image noise and higher vascular SNR and CNR than FBP and HIR at 100 kVp, but slightly inferior to IMR at 100 kVp. IMR also yields the best qualitative image quality, and improves the diagnostic confidence of atherosclerosis and aneurysm. Compared with the standard 120-kVp protocol (1.86mSv), the radiation doses of 100 kVp (1.13mSv) and 80 kVp (0.56mSv) were 39% and 70% less, respectively.The quantitative and qualitative image quality obtained by IMR was superior to that obtained by FBP and HIR for low tube voltage cerebral CTA.

Minimizing Medical Radiation Exposure by Incorporating a New Radiation "Vital Sign" into the Electronic Medical Record: Quality of Care and Patient Safety

There is a clearly perceived and imminent need to decrease unnecessary and detrimental exposure to medical ionizing radiation. We propose a new radiation "vital sign" that incorporates cumulative radiation exposure to create a risk score on the basis of an individualized assessment of potential harm from additional exposure to medical radiation. We propose to then tie the risk score to real-time, evidence-based, clinical decision support for procedures that use ionizing radiation. Additionally, we offer recommendations that minimize unnecessary or low-yield uses. Preference is given to approaches and modalities that use less or no ionizing radiation and that are medically appropriate, acceptable to, and safer for patients.

Diagnostic reference levels for common computed tomography (CT) examinations: results from the first Nigerian nationwide dose survey

PURPOSE

To explore doses from common adult computed tomography (CT) examinations and propose national diagnostic reference levels (nDRLs) for Nigeria.

MATERIALS AND METHODS

This retrospective study was approved by the Nnamdi Azikiwe University and University Teaching Hospital Institutional Review Boards (IRB: NAUTH/CS/66/Vol8/84) and involved dose surveys of adult CT examinations across the six geographical regions of Nigeria and Abuja from January 2016 to August 2017. Dose data of adult head, chest and abdomen/pelvis CT examinations were extracted from patient folders. The median, 75th and 25th percentile CT dose index volume (CTDI_vol) and dose-length-product (DLP) were computed for each of these procedures. Effective doses (E) for these examinations were estimated using the k conversion factor as described in the ICRP publication 103 (E_DLP = _{k × DLP}).

RESULTS

The proposed 75th percentile CTDI_vol for head, chest, and abdomen/pelvis are 61 mGy, 17 mGy, and 20 mGy, respectively. The corresponding DLPs are 1310 mGy.cm, 735 mGy.cm, and 1486 mGy.cm respectively. The effective doses were 2.75 mSv (head), 10.29 mSv (chest), and 22.29 mSv (abdomen/pelvis).

CONCLUSION

Findings demonstrate wide dose variations within and across centres in Nigeria. The results also show CTDI_vol comparable to international standards, but considerably higher DLP and effective doses.

Appropriateness of CT scans for patients with non-traumatic acute abdominal pain

OBJECTIVE

Acute abdominal pain is the most common reason for surgical admission. CT scans are increasingly used to aid early diagnosis. Excessive use of CT scans is associated with increased length of stay, healthcare costs and radiation. The aim of this study was to evaluate the appropriateness of CT scans for patients presenting with acute abdominal pain.

METHODS

We examined 100 consecutive patients presenting with new acute abdominal pain who underwent a CT scan. Clinical information available at the time the scan was ordered, was summarised and reviewed independently by five consultant general surgeons and five consultant radiologists.

RESULTS

A CT scan was judged to be not indicated in a median of 21% of cases (range 12-53%), more information was required in a median of 16% (0-41%) and in a median of 58% (37-88%) the CT scan was considered indicated. There was a good level of agreement (Cronbach's α 0.704) across the 10 experts.

CONCLUSION

These data suggest that a large proportion of CT scans for patients with acute abdominal pain are not clinically indicated or are being performed prior to adequate clinical work-up. Optimising CT scan requests for this patient group will improve use of healthcare resources. Advances in knowledge: Both radiologists and general surgeons agree that there is no indication for an abdominal CT scan for a patient presenting with acute abdominal pain in a median of 21% of the cases.