Effective doses in radiology and diagnostic nuclear medicine: a catalog

Utility of the Merchant View Radiograph for Assessment of Tibial Tubercle-Trochlear Groove Distance: A Comparison to MRI in Pediatric and Adolescent Patients

BACKGROUND

Plain radiographic evaluation remains the standard initial assessment of patellar instability, while 3-dimensional imaging is obtained in some patients. Merchant radiographs can demonstrate the tibial tubercle relative to the trochlear groove (TT-TG), but the determination of the TT-TG from these radiographs has been abandoned since its original description. The purpose of this study is to evaluate the utility of the TT-TG measured on Merchant radiographs for the assessment of patellar instability.

METHODS

A prospective cohort study was performed of pediatric and adolescent patients aged 10 to 18 who underwent standardized Merchant radiographs, including a total of 98 knees (in 57 patients). Merchant TT-TG was measured as the distance between the center of the trochlear groove and the tibial tubercle, with both lines perpendicular to the anterior femoral condylar axis. In Part 1, the Merchant TT-TG measured by the tibial tubercle radiographic appearance was compared with the measurement utilizing a radiographic marker. In Part 2, the Merchant TT-TG was compared with the magnetic resonance imaging (MRI) TT-TG distance using bivariate linear regression analysis. TT-TG measurements were compared in patients with and without patellar instability with receiver operating characteristic curve analysis.

RESULTS

The tibial tubercle was identified on Merchant radiograph in 81.7% (67/82) of knees, and there was an excellent correlation (Pearson correlation coefficient=0.85) between the Merchant TT-TG and the measurement based on marker placement. Merchant TT-TG was on average 4.5 mm less than MRI TT-TG (12.8±4.4 vs. 8.4±7.7 mm, P<0.001) and was moderately correlated (Pearson correlation coefficient=0.58, P<0.01). TT-TG distance was increased in patients with patellar instability compared with those without patellar instability on the Merchant view (10.5±6.9 vs. 2.0±5.5 mm, P<0.001) and MRI (13.9±4.4 vs. 10.5±2.9 mm, P=0.012). Merchant TT-TG also demonstrated a higher area under the curve than MRI TT-TG (0.872 vs. 0.775) in differentiating patients with and without patellar instability.

CONCLUSIONS

Standardized Merchant radiographs allow for reliable assessment of the Merchant TT-TG distance when the tibial tubercle is visualized and moderately correlate with MRI TT-TG (with Merchant TT-TG on average 4.5 mm less than MRI).

LEVEL OF EVIDENCE

Level III.

Women and Lung Cancer

The world is witnessing a global epidemic of lung cancer in women. Cigarette smoking remains the dominant risk factor in both sexes, but multiple observations suggest that important sex-related distinctions in lung cancer exist. These include differences in histologic distribution, prevalence in never-smokers, frequency of activating EGFR mutations, likelihood of DNA adduct accumulation, and survival outcomes. Important questions such as whether women are more susceptible to carcinogenic effects of smoking or derive more benefit from lung cancer screening merit more study. A deeper understanding of sex-related differences in lung cancer may lead to improved outcomes for both women and men.

Computed Tomography in Limb Salvage and Deformity Correction-3D Assessment, Indications, Radiation Exposure, and Safety Considerations

Computed tomography (CT) is an essential tool in orthopedic surgery but is known to be a method with that entails radiation exposure. CT increases the risk of developing fatal cancer, which should not be underestimated. However, patients with bone defects and/or deformities must frequently undergo numerous investigations during their treatment. CT is used for surgical planning, evaluating callus maturation, alignment measurement, length measurement, torsion measurement, and angiography. This study explores the indications in CT scans for limb lengthening and deformity correction and estimates the effective radiation dose. These results should help avoid unnecessary radiation exposure by narrowing the examination field and by providing explicit scanning indications. For this study, 19 posttraumatic patients were included after the bone reconstruction of 21 lower limbs. All patients underwent CT examinations during or after treatment with an external ring fixator. The mean effective dose was 3.27 mSv, with a mean cancer risk of 1:117,014. The effective dose depended on the location and indication of measurement, with a mean dose of 0.04 mSv at the ankle up to 6.8 mSv (or higher) for vascular depictions. CT evaluation, with or without 3D reconstruction, is a crucial tool in complex bone reconstruction and deformity treatments. Therefore, strict indications are necessary to reduce radiation exposure-especially in young patients-without compromising the management of their patients.

Dose reduction potential of vendor-agnostic deep learning model in comparison with deep learning-based image reconstruction algorithm on CT: a phantom study

Objectives

To compare the dose reduction potential (DRP) of a vendor-agnostic deep learning model (DLM, ClariCT.AI) with that of a vendor-specific deep learning–based image reconstruction algorithm (DLR, TrueFidelity™).

Methods

Computed tomography (CT) images of a multi-sized image quality phantom (Mercury v4.0) were acquired under six radiation dose levels (0.48/0.97/1.93/3.87/7.74/15.47 mGy) and were reconstructed using filtered back projection (FBP) and three strength levels of the DLR (low/medium/high). The FBP images were denoised using the DLM. For all DLM and DLR images, the detectability index (d′) (a task-based detection performance metric) was obtained, under various combinations of three target sizes (10/5/1 mm), five inlets (CT value difference with the background; −895/50/90/335/1000 HU), five phantom diameters (36/31/26/21/16 cm), and six radiation dose levels. Dose reduction potential (DRP) measures the dose reduction made by using DLM or DLR, while yielding d′ equivalent to that of FBP at full dose.

Results

The DRPs of the DLM, DLR-low, DLR-medium, and DLR-high were 86% (81–88%), 60% (46–67%), 76% (60–81%), and 87% (78–92%), respectively. For 10-mm targets, the DRP of the DLM (87%) was higher than that of all DLR algorithms (58–86%). However, for smaller targets (5 mm/1 mm), the DRPs of the DLR-high (89/88%) were greater than those of the DLM (87/84%).

Conclusion

The dose reduction potential of the vendor-agnostic DLM was shown to be comparable to that of the vendor-specific DLR at high strength and superior to those of the DLRs at medium and low strengths.

Key Points

• DRP of the vendor-agnostic model was comparable to that of high-strength vendor-specific model and superior to those of medium- and low-strength models.

• Under various radiation dose levels, the deep learning model shows higher detectability indexes compared to FBP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08199-9.

The imaging evaluation of acetabular labral lesions

The acetabular labrum is an important structure that contributes to hip joint stability and function. Diagnosing labral tears involves a comprehensive assessment of clinical symptoms, physical examinations, imaging examinations, and arthroscopic confirmation. As arthroscopy is an invasive surgery, adjuvant imaging of the acetabular labrum is increasingly imperative for orthopedists to diagnose and assess labral lesions prior to hip arthroscopy for surgical management. This article reviews the current imaging strategies for the evaluation of labrum lesions.

Lung nodule detection in chest X-rays using synthetic ground-truth data comparing CNN-based diagnosis to human performance

We present a method to generate synthetic thorax radiographs with realistic nodules from CT scans, and a perfect ground truth knowledge. We evaluated the detection performance of nine radiologists and two convolutional neural networks in a reader study. Nodules were artificially inserted into the lung of a CT volume and synthetic radiographs were obtained by forward-projecting the volume. Hence, our framework allowed for a detailed evaluation of CAD systems' and radiologists' performance due to the availability of accurate ground-truth labels for nodules from synthetic data. Radiographs for network training (U-Net and RetinaNet) were generated from 855 CT scans of a public dataset. For the reader study, 201 radiographs were generated from 21 nodule-free CT scans with altering nodule positions, sizes and nodule counts of inserted nodules. Average true positive detections by nine radiologists were 248.8 nodules, 51.7 false positive predicted nodules and 121.2 false negative predicted nodules. The best performing CAD system achieved 268 true positives, 66 false positives and 102 false negatives. Corresponding weighted alternative free response operating characteristic figure-of-merits (wAFROC FOM) for the radiologists range from 0.54 to 0.87 compared to a value of 0.81 (CI 0.75-0.87) for the best performing CNN. The CNN did not perform significantly better against the combined average of the 9 readers (p = 0.49). Paramediastinal nodules accounted for most false positive and false negative detections by readers, which can be explained by the presence of more tissue in this area.

Dosimetry on first clinical dark-field chest radiography

PURPOSE

The purpose of this study was to evaluate the dose characteristic for patient examinations at the first clinical X-ray dark-field chest radiography system and to determine whether the effective patient dose is within a clinically acceptable dose range.

METHODS

A clinical setup for grating-based dark-field chest radiography was constructed and commissioned, operating at a tube voltage of 70 kVp. Thermoluminescent dosimeter (TLD) measurements were conducted using an anthropomorphic phantom modeling the reference person to obtain a conversion coefficient relating dose area product (DAP) to effective patient dose at the dark-field system. For 92 patients, the DAP values for posterior-anterior measurements were collected at the dark-field system. Using the previously determined conversion coefficient, the effective dose was calculated.

RESULTS

A reference person, modeled by an anthropomorphic phantom, receives an effective dose of 35 µSv. For the examined patients, a mean effective dose of 39 µSv was found.

CONCLUSIONS

The effective dose at the clinical dark-field radiography system, generating both attenuation and dark-field images, is within the range of reported standard dose values for chest radiography.

Calcium functional imaging with high-resolution CT in the inner ear

Although the otolith and otolith organs correlate with vertigo and instability, there is no method to investigate them without harmful procedures. We will create the technique for 3D microanatomical images of them, and investigate the in vivo internal state and metabolisms. The otolith and otolith organs images were reconstructed from a texture synthesis algorithm under the skull volume rendering algorithm using a cutting-plane method. The utricular macula was elongated pea-shaped. The saccular macula was almost bud-shaped. The changes in the amount of CaCO3 in the maculae and the endolymphatic sac showed various morphologies, reflecting the balance status of each subject. Both shapes and volumes were not always constant depending on time. In Meniere's disease (MD), the saccular macula was larger and the utricular macula was smaller. In benign paroxysmal positional vertigo (BPPV), the otolith increased in the utricular macula but did not change much in the saccular macula. The saccule, utricle, and endolymphatic sac were not constantly shaped according to their conditions. These created 3D microanatomical images can allow detailed observations of changes in physiological and biological information. This imaging technique will contribute to our understanding of pathology and calcium metabolism in the in vivo vestibulum.

Subject-Specific Modeling of Femoral Torsion Influences the Prediction of Hip Loading During Gait in Asymptomatic Adults

Hip osteoarthritis may be caused by increased or abnormal intra-articular forces, which are known to be related to structural articular cartilage damage. Femoral torsional deformities have previously been correlated with hip pain and labral damage, and they may contribute to the onset of hip osteoarthritis by exacerbating the effects of existing pathoanatomies, such as cam and pincer morphologies. A comprehensive understanding of the influence of femoral morphotypes on hip joint loading requires subject-specific morphometric and biomechanical data on the movement characteristics of individuals exhibiting varying degrees of femoral torsion. The aim of this study was to evaluate hip kinematics and kinetics as well as muscle and joint loads during gait in a group of adult subjects presenting a heterogeneous range of femoral torsion by means of personalized musculoskeletal models. Thirty-seven healthy volunteers underwent a 3D gait analysis at a self-selected walking speed. Femoral torsion was evaluated with low-dosage biplanar radiography. The collected motion capture data were used as input for an inverse dynamics analysis. Personalized musculoskeletal models were created by including femoral geometries that matched each subject’s radiographically measured femoral torsion. Correlations between femoral torsion and hip kinematics and kinetics, hip contact forces (HCFs), and muscle forces were analyzed. Within the investigated cohort, higher femoral antetorsion led to significantly higher anteromedial HCFs during gait (medial during loaded stance phase and anterior during swing phase). Most of the loads during gait are transmitted through the anterior/superolateral quadrant of the acetabulum. Correlations with hip kinematics and muscle forces were also observed. Femoral antetorsion, through altered kinematic strategies and different muscle activations and forces, may therefore lead to altered joint mechanics and pose a risk for articular damage. The method proposed in this study, which accounts for both morphological and kinematic characteristics, might help in identifying in a clinical setting patients who, as a consequence of altered femoral torsional alignment, present more severe functional impairments and altered joint mechanics and are therefore at a higher risk for cartilage damage and early onset of hip osteoarthritis.

Correlation of image quality parameters with tube voltage in X-ray dark-field chest radiography: a phantom study

Grating-based X-ray dark-field imaging is a novel imaging modality with enormous technical progress during the last years. It enables the detection of microstructure impairment as in the healthy lung a strong dark-field signal is present due to the high number of air-tissue interfaces. Using the experience from setups for animal imaging, first studies with a human cadaver could be performed recently. Subsequently, the first dark-field scanner for in-vivo chest imaging of humans was developed. In the current study, the optimal tube voltage for dark-field radiography of the thorax in this setup was examined using an anthropomorphic chest phantom. Tube voltages of 50–125 kVp were used while maintaining a constant dose-area-product. The resulting dark-field and attenuation radiographs were evaluated in a reader study as well as objectively in terms of contrast-to-noise ratio and signal strength. We found that the optimum tube voltage for dark-field imaging is 70 kVp as here the most favorable combination of image quality, signal strength, and sharpness is present. At this voltage, a high image quality was perceived in the reader study also for attenuation radiographs, which should be sufficient for routine imaging. The results of this study are fundamental for upcoming patient studies with living humans.

Ipsilateral femoral neck and shaft fractures. When do we need further image screening of the hip?

OBJECTIVE

The objective of the present study was to identify patterns of femoral diaphyseal fractures which are associated with fractures of the ipsilateral femoral neck according to the AO classification. We propose an algorithm of investigation based on plain radiographs, recognizing cases that need additional screening with computed tomography.

PATIENTS AND METHODS

This observational retrospective study included patients with combined diaphyseal and femoral neck fractures. These patients were retrieved from a total of 1398 patients with the diagnoses of diaphyseal fractures of the femur, who were admitted to our hospital for surgical treatment between January 2009 and October 2019. All included cases had both fractures analyzed for their geometry and were classified according to the AO Classification, seeking to find a correlation between the types of fractures.

RESULTS

Sixteen diaphyseal fractures associated with ipsilateral neck fractures were detected during the period. The distribution of the diaphyseal fractures according to the AO Classification was as follows: 5 of type A3 (31,2%) 6 type B2 (37.5%), 1 type B3 (6,2%), 2 type C2 (12,5%) and 2 type C3 (12,5%). One A2 femoral fracture occurred during the surgical procedure. No type A1 fractures were detected.

CONCLUSION

The patterns of high-energy diaphyseal fractures (A3, B and C) have a higher prevalence of associated ipsilateral neck fractures. Our study suggests that routine additional methods of image investigation of femoral neck fractures may be unnecessary for diaphyseal fractures type A1 and A2.

Low-dose computed tomography for axial spondyloarthritis: update on use and limitations

PURPOSE OF REVIEW

Recent developments in low-dose computed tomography (ldCT) have greatly reduced radiation exposure levels. This article reviews what a ldCT is and its use and limitations for imaging axial spondyloarthritis.

RECENT FINDINGS

Detection of structural damage in bone with CT is far superior to radiography and ldCT of the sacroiliac joints (SIJ) can now be done at radiation exposure levels equivalent to, or even less than, conventional radiography. ldCT should be considered a 'first-choice' test for arthritis imaging, and wherever available, SIJ ldCT may completely replace conventional radiography. Radiation exposure in the spine with ldCT is lower than conventional CT. However, it is unclear whether the additional information regarding structural damage changes in the spine provided by ldCT will alter patient management sufficiently often to merit switching from spinal radiography to ldCT in routine clinical practice. In addition, ldCT cannot assess osteitis disease activity for which MRI remains the best test.

SUMMARY

ldCT of the sacroiliac joints (SIJ) can be done at radiation exposure levels equivalent to, or less than, radiography and ldCT may completely replace SIJ radiography. However, the role of spinal ldCT for spondyloarthritis is not clear and MRI is far superior for detecting disease activity.

Evaluation of Dynamic Carpal Arch Stability following Carpal Tunnel Release Using Four-Dimensional Computed Tomography

Introduction  This study aimed to assess the carpal arch dynamics during active finger and wrist motion following carpal tunnel release using four-dimensional computed tomography (4D-CT). Materials and Methods  Four patients who diagnosed with bilateral carpal tunnel syndrome and underwent unilateral carpal tunnel release were prospectively included. 4D-CT of the bilateral wrists during active finger and wrist motion was performed for 10 seconds at five frames per second. The distances between the tip of tuberosity of the scaphoid and the volar ridge of the pisiform (S-P distance) and volar ridge of trapezium and the tip of hook of hamate (T-H distance) were measured at each position and the values of S-P and T-H distances were compared between the postoperative and contralateral wrists. Results  During finger motion, the S-P and T-H distances were not different at any position between the postoperative side and contralateral side. Conversely, S-P and T-H distances gradually increased in the postoperative wrists. The differences between the sides of S-P distance were significant, with >0 degrees of wrist extension, and differences of T-H distance were significant with >15 degrees of wrist extension. Conclusion  This study demonstrated the carpal arch dynamics using 4D-CT and revealed that the carpal arch was widened with the wrist in extension after carpal tunnel release. This study suggests that the transverse carpal ligament plays an important role in maintaining carpal arch stability.

Radiation Reduction Strategies in Pediatric Orthopaedics

INTRODUCTION

Pediatric orthopaedic patients have the potential for significant radiation exposure from the use of imaging studies, such as computed tomography and bone scintigraphy. With the potential for long-term treatment, such as is required for scoliosis or osteogenesis imperfecta, patients are at even greater risk of radiation-induced carcinogenesis.

DISCUSSION

Although an association between radiation and cancer risk is evident, causation is difficult to prove because comorbidities or genetic predispositions may play a role in the higher baseline rates of malignancy later in life. Efforts have been made over the years to reduce exposure using more modern imaging techniques and simple radiation reduction strategies. Educational efforts and clinical practice guidelines are decreasing the rate of computed tomography scan use in pediatrics. Although considerable work is being done on the development of radiation-free imaging modalities, imaging that uses ionizing radiation will, in the near term, be necessary in specific circumstances to provide optimal care to pediatric orthopaedic patients.

CONCLUSION

Knowledge of the ionizing radiation exposure associated with commonly used tests as well as radiation-reduction strategies is essential for the optimal and safe care of pediatric orthopaedic patients.

Early low-dose computed tomography with pulmonary angiography to improve the early diagnosis of invasive mould disease in patients with haematological malignancies: A pilot study

OBJECTIVE

High-resolution computed tomography (CT) is an essential diagnostic tool for invasive mould disease (IMD) in patients with haematological malignancies but is infrequently performed in the first 72 h of neutropenic fever until after chest X-ray (CXR). We hypothesised that early (< 48 h) low-dose CT (LD-CT; 90% reduction in radiation dose) combined with CT pulmonary angiography (CTPA) to detect the venous occlusion sign (VOS) inside suspected infiltrates could improve IMD diagnosis.

METHODS

We prospectively studied 68 consecutive adult patients undergoing treatment for haematological malignancies who developed fever following chemotherapy or haematopoietic stem cell transplantation. Within 48 h of fever, patients underwent a standard CXR followed by LD-CT imaging and CTPA if eligible based on baseline imaging findings; the same protocol was performed in 42/68 (61.7%) of patients at day 7 follow-up. The diagnostic performance of CT signs for EORTC/MSG-defined proven, probable, and possible IMD was analysed at both imaging periods.

RESULTS

The baseline LD-CT was positive for abnormalities in 43/68 (63%) of patients within 48 h of fever and 35/42 (83%) of patients at the follow-up exam. Amongst these 43 patients, CTPA was performed in 17/43 (39%) and in 18/35 (51%) at D + 7 follow-up. A positive VOS was associated with the highest estimated positive likelihood ratio for EORTC/MSG-defined proven, probable, or possible IMD at baseline (20.6; 95% CI 1.4-311.2) and at day 7 follow-up (19.0; 95% CI 0.93-300.8) followed by the baseline non-contrast enhanced hypodense sign (18.3; 0.93-361.7), reverse halo (11.0; 0.47-256.5), halo sign (8.68;3.13-24.01) and air-crescent sign at day 7 (16.7; 0.93-301.0). However, a negative VOS was the only CT sign at baseline or day 7 associated with sufficiently low negative likelihood ratio (0.05;0.001-0.8) to possibly support ruling-out IMD in patients with positive CT findings.

CONCLUSIONS

Early LD-CT combined with CTPA shows promise for improving the early radiographic diagnosis of IMD.

Current Applications and Selected Technical Details of Dual-Energy X-Ray Absorptiometry

The application of dual-energy X-ray absorptiometry (DXA) examinations in the assessment of bone mineral density (BMD) in the lumbar spine, hip, and forearm is the basic diagnostic method for recognition of osteoporosis. The constant development of DXA technique is due to the aging of societies and the increasing importance of osteoporosis as a public health problem. In order to assess the degree of bone demineralization in patients with hyperparathyroidism, forearm DXA examination is recommended. The vertebral fracture assessment (VFA) of the thoracic and lumbar spine, performed by a highly-skilled technician, is an interesting alternative to the X-ray examination. The DXA total body examination can be useful in the evaluation of fat redistribution among patients after bariatric surgery, in patients infected with HIV and receiving antiretroviral therapy, and in patients with metabolic diseases and suspected to have sarcopenia. The assessment of visceral adipose tissue (VAT) and detection of abdominal aortic calcifications may be useful in the prediction of cardiovascular events. The positive effect of anti-resorptive therapy may affect some parameters of DXA hip structure analysis (HSA). Long-term anti-resorptive therapy, especially with the use of bisphosphonates, may result in changes in the DXA image, which may herald atypical femur fractures (AFF). Reduction of the periprosthetic BMD in the DXA measurements can be used to estimate the likelihood of loosening the prosthesis and periprosthetic fractures. The present review aims to present current applications and selected technical details of DXA.

Contemporaneous and temporal interrelationships between menstrual fluctuations in sex hormones and DXA estimates of body composition in a premenopausal female: a case study

The reliability of dual energy X-ray absorptiometry (DXA) to assess body composition is influenced by factors like hydration status. Hence, any factor affecting total body water (TBW) content, such as menstrual shifts in sex hormones, might influence DXA estimates of lean soft tissue (LST) and fat mass (FM). To address this possibility, interrelationships between menstrual fluctuations in sex hormones, LST and FM were examined in a premenopausal female. The participant was monitored over 40 consecutive days for LST, FM and TBW by bioelectrical impedance. Daily capillary blood samples were taken to track 17β-estradiol, progesterone, and luteinizing hormone (LH). Using a graphical vector autoregression model, variable interrelationships were tested in a contemporaneous network (same measurement window) and temporal network (next measurement window). In the contemporaneous network, LST was related to TBW (r=0.42) and FM (r=-0.34). The temporal network uncovered directional effects of TBW (r=0.14), FM (r=-0.59) and LST (r=-0.50) on progesterone concentration. Hormonal interrelationships also emerged in the temporal network, whereby LH (r=0.24) and 17β-estradiol (r=0.13) were related to progesterone, and each hormone was related (r=0.50-0.69) to itself. The menstrual profiling of a premenopausal female revealed interrelationships between body composition and water content, but sex hormone fluctuations did not correlate with TBW, FM and LST on the same day or following day in the hypothesized direction. The temporal between- and within-hormone linkages reflect those natural feedback loops that control hormone secretion.

Preoperative Cardiovascular Assessment of the Renal Transplant Recipient: A Narrative Review

Patients with end-stage kidney disease (ESKD) have a high prevalence of cardiovascular disease; it is the leading cause of death in these patients and the optimisation of their cardiovascular health may improve their post-transplant outcomes. Patients awaiting renal transplant often spend significant amounts of time on the waiting list allowing for the assessment and optimisation of their cardiovascular system. Coronary artery disease (CAD) is commonly seen in these patients and we explore the possible functional and anatomical investigations that can help assess and manage CAD in renal transplant candidates. We also discuss other aspects of cardiovascular assessment and management including arrhythmias, impaired ventricular function, valvular disease, lifestyle and pulmonary arterial hypertension. We hope that this review can form a basis for centres hoping to implement an enhanced recovery after surgery (ERAS) protocol for renal transplantation.

Imaging Modalities for Evaluation of Intestinal Obstruction

It is essential for the colon and rectal surgeon to understand the evaluation and management of patients with both small and large bowel obstructions. Computed tomography is usually the most appropriate and accurate diagnostic imaging modality for most suspected bowel obstructions. Additional commonly used imaging modalities include plain radiographs and contrast imaging/fluoroscopy, while less commonly utilized imaging modalities include ultrasonography and magnetic resonance imaging. Regardless of the imaging modality used, interpretation of imaging should involve a systematic, methodological approach to ensure diagnostic accuracy.

Birth outcomes in women exposed to diagnostic radiology procedures during first trimester of pregnancy: a prospective cohort study

INTRODUCTION

Exposure of the embryo or fetus to ionizing radiations is a potential danger since it may induce clinically relevant fetal and/or neonatal damages. The aim of the present study was to examine fetal and neonatal outcomes after maternal exposure to radio-diagnostic procedures during first trimester of pregnancy, and to evaluate whether these effects might be related to the fetal absorbed dose of ionizing radiations.

METHODS

A 10-year prospective cohort study was performed on 1979 pregnant women who underwent a radio-diagnostic procedure within the first trimester of pregnancy. Women were divided into two groups: those exposed to abdominal or lumbar radio-diagnostic procedure (Cohort A, n = 130), and those exposed to radio-diagnostic procedures in any other body regions (Cohort B, n = 415). Health physicists performed tailored fetal radiation dose calculation. Multivariate logistic regression model was used to estimate the risk of adverse pregnancy outcomes.

RESULTS

The tailored fetal radiation dose was calculated for a total of 97 women (range 0.05-92 mSv). Major congenital malformations were detected in four infants in Cohort A, six infants in Cohort B, and 24 infants in controls (p = 0.445). Multivariate analysis confirmed the negative association between age and adverse pregnancy outcomes (OR 1.08 [1.06-1.11]), and the protective role of folic acid. A higher rate of small for gestational age seems to be present in women who underwent radio-diagnostic procedures that involve maternal thyroid.

CONCLUSION

Despite several limitations, our study confirms that exposure to radio-diagnostic procedures that may involve uterus at doses below 100 mSv does not increase the risk of embryo-fetal toxicity. The relationship between maternal thyroid irradiation and small for gestational age needs to be further investigated.

Novelties in Imaging of Thoracic Sarcoidosis

Sarcoidosis is a systemic granulomatous disease affecting various organs, and the lungs are the most commonly involved. According to guidelines, diagnosis relies on a consistent clinical picture, histological demonstration of non-caseating granulomas, and exclusion of other diseases with similar histological or clinical picture. Nevertheless, chest imaging plays an important role in both diagnostic assessment, allowing to avoid biopsy in some situations, and prognostic evaluation. Despite the demonstrated lower sensitivity of chest X-ray (CXR) in the evaluation of chest findings compared to high-resolution computed tomography (HRCT), CXR still retains a pivotal role in both diagnostic and prognostic assessment in sarcoidosis. Moreover, despite the huge progress made in the field of radiation dose reduction, chest magnetic resonance (MR), and quantitative imaging, very little research has focused on their application in sarcoidosis. In this review, we aim to describe the latest novelties in diagnostic and prognostic assessment of thoracic sarcoidosis and to identify the fields of research that require investigation.

Body packing, body stuffing and body pushing: Characteristics and pitfalls on low-dose CT

Because of availability and low radiation dose level, low dose computed tomography (CT) is now commonly used to identify illicit in corpore drug transportation. This review illustrates the most common CT findings of in corpore drug transportation and describes complications due to in corpore drug transportation, with a special emphasis on low dose CT. Major information such as number of packets, exact location and aspect of packets must be assessed. Radiologist must be aware of the imaging characteristics of "in corpore" illicit drug transportation, and should know situations that may alter drug smugglers management.

Combination of Side-Bending and Traction Radiographs Do Not Influence Selection of Fusion Levels Compared to Either One Alone in Adolescent Idiopathic Scoliosis

STUDY DESIGN

A retrospective study.

OBJECTIVES

Curve flexibility in patients with adolescent idiopathic scoliosis (AIS) can be evaluated using different techniques. This study aimed to determine whether the combination of side-bending (SB) and traction (TX) radiographs influences preoperative planning for AIS than either radiograph alone.

METHODS

Thirty-two spine surgeons were asked to review 30 AIS Lenke type 1 cases and select an upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV) for the posterior spinal instrumentation of each case. Each rater reviewed the cases 3 times in each round. The raters were provided with the full-length posteroanterior (PA) and lateral standing and SB radiographs for round 1; PA, lateral, and TX radiographs for round 2; and PA, lateral, SB, and TX radiographs for round 3. Intra- and inter-rater reliabilities were evaluated using Kappa statistics.

RESULTS

The intra-rater reliability for UIV and LIV was 0.657 and 0.612 between rounds 1 and 2, 0.634 and 0.692 between rounds 1 and 3, and 0.659 and 0.638 between rounds 2 and 3, respectively, which indicated substantial agreement between rounds. The inter-rater kappa reliabilities for UIV and LIV selection were 0.103 and 0.412 for round 1, 0.121 and 0.380 for round 2, and 0.125 and 0.368 for round 3, indicating slight to moderate agreement between raters.

CONCLUSIONS

Whether raters used either SB or TX radiography, or both in addition to PA and lateral standing radiographs, did not influence the decision making for UIV or LIV of AIS Lenke type 1 surgery.

Bowel transit studies in children: evidence base, role and practicalities

Constipation is common in children and adults with varied worldwide prevalence. The majority of children have functional constipation as defined by Rome clinical criteria and respond favourably to standard medical therapy; up to one-third can develop difficult-to-treat constipation requiring investigation and specialist treatment. Colon function tests aim to assess the neuromuscular integrity, the movement of faeces across the colon and evaluate/predict response to the therapy. The 'ideal' test should be practical, non-invasive, widely available and cost-effective. None of the available diagnostic tools is designed to provide a comprehensive assessment of colon function and clinicians often have to combine more than one test to answer different questions. In this review, we aim to assess the strengths and limitations of the commonly available diagnostic investigations (radiopaque marker studies, scintigraphy, wireless motility capsule and colonic manometry) used to assess colon transit in children and to provide guidance on the most appropriate test for particular clinical settings.

Monte Carlo evaluation of occupational exposure during uterine artery embolization

PURPOSE

Uterine fibroids affect women mainly of childbearing age, an alternative for the treatment of these fibroids is uterine artery embolization (UAE), a minimally invasive procedure which uses fluoroscopy, providing radiation doses often high, due to the fact that professionals remain in the room throughout the procedure. In this work, equivalent and effective doses were evaluated for the main physician, for the assistant and for the patient during the UAE procedure.

METHODS

Doses were calculated using computer simulation with the Monte Carlo Method, and virtual anthropomorphic phantoms, in a typical scenario of interventional radiology with field sizes of 20 × 20, 25 × 25 and 32 × 32 cm², tube voltages of 70, 80, 90 and 100 kV, and projections of LAO45, RAO45 and PA.

RESULTS

The results showed that the highest doses received by the professionals were for the LAO45 projection with 32 × 32 cm² field size and 100 kV tube voltage, which is in accordance with the existing literature. The highest equivalent doses, without the protective equipment, were in the eyes, skin, breast and stomach for the main physician, and for the assistant they were in the eyes, breast, thyroid and skin. When she used the protective equipment, the highest equivalent doses for the main physician were on the skin, brain, bone marrow and bone surface, and for the assistant they were on the skin, brain, red bone marrow and bone surface.

CONCLUSIONS

Effective doses increased up to 3186% for the main physician, and 2462% for the assistant, without protective equipment, thus showing their importance.

Automated Bone Age Assessment Using Artificial Intelligence: The Future of Bone Age Assessment

Bone age assessments are a complicated and lengthy process, which are prone to inter- and intra-observer variabilities. Despite the great demand for fully automated systems, developing an accurate and robust bone age assessment solution has remained challenging. The rapidly evolving deep learning technology has shown promising results in automated bone age assessment. In this review article, we will provide information regarding the history of automated bone age assessments, discuss the current status, and present a literature review, as well as the future directions of artificial intelligence-based bone age assessments.

Clinical concordance with Image Gently guidelines for pediatric computed tomography: a study across 663,417 CT scans at 53 clinical facilities

BACKGROUND

Managing patient radiation dose in pediatric computed tomography (CT) examinations is essential. Some organizations, most notably Image Gently, have suggested techniques to lower dose to pediatric patients and mitigate risk while maintaining image quality.

OBJECTIVE

We sought to validate whether institutions are observing Image Gently guidelines in practice.

MATERIALS AND METHODS

Dose-relevant data from 663,417 abdomen-pelvis and chest CT scans were obtained from 53 facilities. Patients were assigned arbitrary age cohorts with a minimum size of n=12 patients in each age group, for statistical purposes. All pediatric (<19 years old) cohorts at a given facility were compared to the adult cohort by a Kruskal-Wallis test for each of the four scan parameters - (1) x-ray tube kilovoltage (kV), (2) tube-current-by-exposure-time product (tube mAs), (3) scan pitch and (4) tube rotation time - to assess whether the distribution of values in the pediatric cohorts differed from the adult cohort. The same was repeated with volume CT dose index (CTDI_vol) and size-specific dose estimate (SSDE) to assess whether pediatric cohorts received less dose than adult cohorts. A P-value of <0.05 was deemed significant.

RESULTS

Across the 150 pediatric cohorts, 134 had scan parameters that were more child-sized than their adult counterparts. In 128 of these 134 pediatric cohorts, the CTDI_vol was less than the adult counterpart. In 111 of these 128 pediatric cohorts, the SSDE was less than the adult counterpart.

CONCLUSION

The study reaffirms that in practice, Image Gently's suggestions of lowering tube mAs and peak kilovoltage are commonly employed and effective at reducing pediatric CT dose.

Radiation Effective Doses to Adults Undergoing Modified Barium Swallow Studies

Modified Barium Swallow Studies (MBSSs) are important tests to aid the diagnosis of swallowing impairment and guide treatment planning. Since MBSSs use ionizing radiation, it is important to understand the radiation exposure associated with the exam. This study reports the average radiation dose in routine clinical MBSSs, to aid the evidence-based decision-making of clinical providers and patients. We examined the MBSSs of 200 consecutive adult patients undergoing clinically indicated exams and used kilovoltage (kV) and Kerma Area Product to calculate the effective dose. While 100% of patients underwent the exam in the lateral projection, 72% were imaged in the upper posterior-anterior (PA) projection and approximately 25% were imaged in the middle and lower PA projection. Average kVs were 63 kV, 77 kV, 78.3 kV, and 94.3 kV, for the lateral, upper, middle, and lower PA projections, respectively. The average effective dose per exam was 0.32 ± 0.23 mSv. These results categorize a typical adult MBSS as a low dose examination. This value serves as a general estimate for adults undergoing MBSSs and can be used to compare other sources of radiation (environmental and medical) to help clinicians and patients assess the risks of conducting an MBSS. The distinction of MBSS as a low dose exam will assuage most clinician's fears, allowing them to utilize this tool to gather clinically significant information about swallow function. However, as an X-ray exam that uses ionizing radiation, the principles of ALARA and radiation safety must still be applied.

Cumulative radiation dose incurred during the management of complex pleural space infection

BACKGROUND

Complex pleural space infections are commonly managed with antibiotics, pleural drainage, intrapleural fibrinolytic therapy, and surgery. These strategies often utilize radiographic imaging during management, however little data is available on cumulative radiation exposure received during inpatient management. We aimed to identify the type and quantity of radiographic studies along with the resultant radiation exposure during the management of complex pleural space infections.

METHODS

Retrospective review of community network healthcare system from January 2015 to July 2018. Patients were identified through billing databases as receiving intrapleural fibrinolytic therapy and/or surgical intervention. Patient demographics, clinical outcomes, and inpatient radiographic imaging was collected to calculate cumulative effective dose.

RESULTS

A total of 566 patients were identified with 7275 total radiographic studies performed and a median cumulative effective dose of 16.9 (IQR 9.9-26.3) mSv. Multivariable linear regression analysis revealed computed tomography use was associated with increased cumulative dose, whereas increased age was associated with lower cumulative dose. Over 74% of patients received more than 10 mSv, with 7.4% receiving more than 40 mSv.

CONCLUSIONS

The number of radiographic studies and overall cumulative effective dose in patients hospitalized for complex pleural space infection was high with the median cumulative effective dose > 5 times normal yearly exposure. Ionizing radiation and modern radiology techniques have revolutionized medical care, but are likely not without risk. Additional study is warranted to identify the frequency and imaging type needed during complex pleural space infection management, attempting to keep ionizing radiation exposure as low as reasonably possible.

Are We Overradiating Patients with Irritable Bowel Syndrome?

Introduction

Protracted exposures to small doses of radiation, even cumulative effective doses (CED) as low as 50-100 mSv, may increase the risk for malignancy. Medical radiation exposure has not been rigorously examined for patients with irritable bowel syndrome (IBS). We examined medical radiation exposure in patients with IBS at a tertiary care center in the USA.

Methods

Patients diagnosed with IBS at our institute from 2009 to 2018 were included in a retrospective cohort study. Medical charts were examined to calculate total and annual CED.

Results

221 patients were included; mean CED was 40.32 mSv (SD: 54.36). Fifty-nine participants (26.7%) received >50 mSv of CED with 27 participants (12.2%) exceeding 100 mSv. Conventional imaging, nuclear medicine, and fluoroscopy accounted for 74.08, 12.93, and 12.98% of total CED, respectively. CT scans contributed to 66.61% of total CED. Outpatient orders accounted for 37.96% of total CED, while 31.4% of total CED was ordered in the emergency department. Population-specific high total CED was calculated as 105.65 mSv. Multivariable binomial logistic regression model found that comorbid anxiety, chronic pain medication use, and diarrhea-predominant IBS were independently positively associated with population-specific high CED exposure. No significant temporal trend in peri-diagnostic mean CED was found.

Conclusion

Patients with IBS receive high amounts of medical radiation, with 1 in 4 patients reaching at-risk levels of 50 mSv or more. Usage of pain medication at home, comorbid anxiety, and IBS-D are independently linked to an increased risk of high CED.

Strategy to reduce radiation exposure in postoperative spinal computed tomography scans

Background:

When diagnosing and treating spinal disorders, spine surgeons commonly utilize computed tomography (CT) scans preoperatively, intraoperatively, and postoperatively.

Methods:

This article reviews the literature regarding the potentially harmful effects of X-rays, specifically from CT scans.

Results:

The risk for damaging DNA and developing cancer increases with increasing scan length (e.g., increasing amount of radiation received).

Conclusion:

When assessing postoperative status, CT scans should be directed only through the area of specific interest to limit the total dose of radiation received by the patient.

FACTORS AFFECTING PATIENT RADIATION EXPOSURE DURING PRONE AND SUPINE PERCUTANEOUS NEPHROLITHOTOMY

Purpose Radiation exposure from fluoroscopy poses risks to patients and surgeons. Percutaneous Nephrolithotomy (PCNL) has traditionally required fluoroscopy, however the use of ultrasound (US) has decreased radiation exposure. US-guidance in supine PCNL may further reduce radiation exposure. In this study we investigate patient and operative factors affecting fluoroscopy time (s), total radiation dose (mGy) and effective radiation dose (ERD) (mSv) in patients undergoing US-guided supine or prone PCNL. Methods: We performed a retrospective study of patients undergoing US-guided PCNL in prone position and supine position. Patients with multiple access tracts, pre-existing renal access or fluoroscopic renal access were excluded. Patient demographic, radiologic and operative data were collected, and compared between the two groups. Results: 99 patients were included: 45 prone (P-PCNL) and 54 supine (S-PCNL). There were no significant demographic differences between the two groups. Operative time, access location, tract length and total radiation dose (mGy) also did not differ. S-PCNL was associated with lower ERD (2.92mSv ± 0.32 vs 5.3mSv ± 0.7, p=0.0014) despite increased fluoroscopy time (86.32s ± 7.7 vs. 51.00s ± 5.1, p=0.004), and was more likely a mini-PCNL (35.2‰ vs 15.9‰, p=0.032). In multivariate analysis, supine PCNL remained associated with reduced ERD compared to prone (p=0.002), whereas BMI (p<0.001) and staghorn calculi (p<0.001) were independently associated with increased ERD.

Diagnosis of acute appendicitis in children using urinary 5-hydroxy indol acetic acid and pediatric appendicitis score: A randomized control trial

Purpose

Acute appendicitis in children represents a common problem. Diagnosis may be difficult due to lack of clinical data. Several scoring systems and laboratory investigations are used for diagnosis. This study aimed to build a model for diagnosis of acute appendicitis in children using urinary 5-hydroxyindoleacetic acid (5-HIAA) and pediatric appendicitis score.

Methods

This study was conducted on 191 children with suspicion of acute appendicitis. They were divided into two groups A and B. Children were evaluated in group A with pediatric appendicitis score, ultrasound, and CRP. In group B children were evaluated in the same manner of group A plus measuring of 5-HIAA.

Results

mean age was 13.3 ± 5.2 years. The mean duration of symptoms was 2.2 ± 1.4 days. The mean level of urinary 5-HIAA was 43.53 ± 24.05 in appendicitis patients in group B. In group A there were 65 cases who had appendectomy. Seventy-five children were operated in group B. Negative appendectomies were found in 13 and 7 cases in groups A and B respectively. Thirteen cases were readmitted in group A with diagnosis of acute appendicitis while seven cases were readmitted in group B.

Conclusion

This combination of urinary 5-HIAA and pediatric appendicitis score builds a model for diagnosis of acute appendicitis in children. This model improves the accuracy of diagnosis of acute appendicitis, reduces both the incidence of negative appendectomies and the incidence of readmission or missed cases in children.

Image quality of EOS low-dose radiography in comparison with conventional radiography for assessment of ventriculoperitoneal shunt integrity

OBJECTIVE

Patients with shunted hydrocephalus often accumulate high levels of radiation over their lifetimes during evaluation of hardware integrity. Current practice involves the use of a series of conventional radiographs for this purpose. Newer low-dose EOS radiography is currently used to evaluate scoliosis but has not been explored to evaluate shunt integrity on a large scale. The goal of this study was to compare the quality of imaging using EOS low-dose radiography to conventional radiography to evaluate shunt tubing.

METHODS

A retrospective chart review was performed on 57 patients who previously had both conventional radiographs and low-dose EOS images of their cerebral shunt tubing from 2000 to 2018. Patient demographics (age, sex, type of shunt tubing, primary diagnosis) were collected. Conventional radiographic images and low-dose EOS images were independently analyzed by a neurosurgeon and neuroradiologist in three categories: image quality, delineation of shunt, and distinction of shunt compared to adjacent anatomy.

RESULTS

All patients had shunted hydrocephalus due to spina bifida and Chiari type II malformation. Ratings of EOS and conventional radiographic images by both raters did not differ significantly in terms of image quality (rater 1, p = 0.499; rater 2, p = 0.578) or delineation of shunt (p = 0.107 and p = 0.256). Conventional radiographic images received significantly higher ratings than EOS on the ability to distinguish the shunt versus adjacent anatomy by rater 1 (p = 0.039), but not by rater 2 (p = 0.149). The overall score of the three categories combined was not significantly different between EOS and conventional radiography (rater 1, p = 0.818; rater 2, p = 0.186). In terms of cost, an EOS image was less costly than a conventional radiography shunt series ($236-$366 and $1300-$1547, respectively). The radiation dose was also lower for EOS images, with an effective dose of 0.086-0.140 mSv compared to approximately 1.6 mSv for a similar field of view with conventional radiography.

CONCLUSIONS

The image quality of low-dose EOS radiography does not significantly differ from conventional radiography for the evaluation of cerebral shunts. In addition, EOS affords a much lower radiation dose and a lower cost.

Tables for effective dose assessment from diagnostic radiology (period 1946-1995) in epidemiologic studies

Diagnostic radiology is a leading cause of man-made radiation exposure to the population. It is an important factor in many epidemiological studies as variable of interest or as potential confounder. The effective dose as a risk related quantity is the most often stated patient dose. Nevertheless, there exists no comprehensive quantification model for retrospective analysis for this quantity. This paper gives a catalog of effective dose values for common and rare examinations and demonstrates how to modify the dose values to adapt them to different calendar years using a quantification concept already used for retrospective analysis of the red bone marrow dose. It covers the time period of 1946 to 1995 and allows considering technical development and different practical standards over time. For an individual dose assessment, if the dose area product is known, factors are given for most examinations to convert the dose area product into the effective dose. Additionally factors are stated for converting the effective dose into the red bone marrow dose or vice versa.

The potential application of dual-energy subtraction radiography for COVID-19 pneumonia imaging

X-ray imaging plays a crucial role in the confirmation of COVID-19 pneumonia. Chest X-ray radiography and CT are two major imaging techniques that are currently adopted in the diagnosis of COVID-19 pneumonia. However, dual-energy subtraction radiography is hardly discussed as potential COVID-19 imaging application. More advanced X-ray radiography equipment often supports dual-energy subtraction X-ray radiography. Dual-energy subtraction radiography enables the calculation of pseudo-radiographs, in which bones are removed and only soft-tissues are highlighted. In this commentary, the author would like to draw the attention to the potential use of dual-energy subtraction X-ray radiography (i.e. soft-tissue pseudo-radiography) for the assessment and the longitudinal follow-up of COVID-19 pneumonia.

Differences in airway lumen area between supine and upright computed tomography in patients with chronic obstructive pulmonary disease

BACKGROUND

No clinical studies to date have compared the inspiratory and expiratory airway lumen area between supine and standing positions. Thus, the aims of this study were twofold: (1) to compare inspiratory and expiratory airway lumen area (IAA and EAA, respectively) on computed tomography (CT) among supine and standing positions; and (2) to investigate if IAA and EAA are associated with lung function abnormality in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Forty-eight patients with COPD underwent both low-dose conventional (supine position) and upright CT (standing position) during inspiration and expiration breath-holds and a pulmonary function test (PFT) on the same day. We measured the IAA and EAA in each position.

RESULTS

For the trachea to the third-generation bronchi, the IAA was significantly larger in the standing position than in the supine position (4.1-4.9% increase, all p < 0.05). The EAA of all bronchi was significantly larger in the standing position than in the supine position (9.7-62.5% increases, all p < 0.001). The correlation coefficients of IAA in the standing position and forced expiratory volume in 1 s were slightly higher than those in the supine position. The correlation coefficients of EAA or EAA/IAA in the standing position and residual volume, and the inspiratory capacity/total lung capacity ratio were higher than those in the supine position.

CONCLUSIONS

Airway lumen areas were larger in the standing position than in the supine position. IAAs reflect airway obstruction, and EAAs reflect lung hyperinflation. Upright CT might reveal these abnormalities more precisely. Trial registration University Hospital Medical Information Network (UMIN 000026587), Registered 17 March 2017. URL: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000030456 .

A retrospective audit of cumulative ionising radiation levels in hospitalised pregnant patients

BACKGROUND

Among hospitalised patients, diagnostic radiation is possibly used least on pregnant patients due to the fear of ionising radiation on the fetus; however, what levels are currently being prescribed?

AIMS

To assess the cumulative levels of ionising radiation received by pregnant patients during a single admission to a tertiary hospital.

MATERIALS AND METHODS

A retrospective audit of pregnant patients admitted to Flinders Medical Centre, South Australia, Australia, between 2013 and 2017 inclusive was performed. All procedures utilising ionising radiation were collected including conventional radiology, computed tomography, fluoroscopy and nuclear medicine. Individual and cumulative effective doses for mother and fetus were calculated using patient dose reports and published conversion factors.

RESULTS

From 547 patients, the median cumulative effective dose was 0.02 mSv and only five patients received more than 10 mSv, with 19.07 mSv the highest dose received. The median fetal cumulative effective dose was 0.01 mSv but only three fetuses received more than 10 mSv, likely due to fetal exclusion in some procedural fields of view. Stays longer than ten days were associated with significantly higher cumulative effective dose, as did those with maternal cardiovascular related admission, for both maternal and fetal exposures.

CONCLUSION

These results suggest that pregnant patients are exposed to low doses of ionising radiation, in both individual procedures and cumulative doses. The detrimental risks associated with these levels of ionising radiation are not overt and so clinicians should question which risk is higher, the ionising radiation from the radiological procedures received or the lack of diagnostic information if avoided?

Computed tomography colonography and radiation risk: How low can we go?

Computed tomography colonography (CTC) has become a key examination in detecting colonic polyps and colorectal carcinoma (CRC). It is particularly useful after incomplete optical colonoscopy (OC) for patients with sedation risks and patients anxious about the risks or potential discomfort associated with OC. CTC's main advantages compared with OC are its non-invasive nature, better patient compliance, and the ability to assess the extracolonic disease. Despite these advantages, ionizing radiation remains the most significant burden of CTC. This opinion review comprehensively addresses the radiation risk of CTC, incorporating imaging technology refinements such as automatic tube current modulation, filtered back projections, lowering the tube voltage, and iterative reconstructions as tools for optimizing low and ultra-low dose protocols of CTC. Future perspectives arise from integrating artificial intelligence in computed tomography machines for the screening of CRC.

Risk of Second Primary Malignancies among Patients with Early Gastric Cancer Exposed to Recurrent Computed Tomography Scans

Simple Summary

Cancer risk after radiation exposure during childhood has been extensively documented in the literature, although cancer risk associated with recurrent computed tomography (CT) scans during adulthood is less understood. We found a significant relationship between the frequency of CT scans and the subsequent incidence of secondary primary malignancies in patients who have undergone curative resection for early gastric cancer (EGC). On the basis of the low incidence of extragastric recurrence and the risk of radiation exposure, we suggest that overzealous CT surveillance should be avoided in adult patients with EGC.

Abstract

Although computed tomography (CT) scans are very useful for identification or surveillance of malignancy, they are also associated with the risk of cancer caused by ionizing radiation. We investigated the risk of second primary malignancies (SPMs) after frequent abdominopelvic CT scans in a cohort of Korean patients with early gastric cancer (EGC). We performed a cohort study of 11,072 patients who underwent resection for EGC at Samsung Medical Center and validated the results using data from 7908 patients in a Korean National Health Insurance Service cohort. Cox proportional hazards regression model was used to estimate hazard ratios (HRs) for intra-abdominal SPM. During 43,766.5 person-years of the follow-up at our center, 322 patients developed intra-abdominal SPMs. Patients who underwent receiving >8 abdominopelvic CT scans had a significantly greater risk of developing SPM (HR, 2.73; 95% CI, 1.66–4.50; p < 0.001) than those who had with ≤8 scans. For each additional abdominopelvic CT scan, the adjusted HR for SPM was 1.09 (95% confidence interval (CI), 1.03–1.14). Similar results were observed in the Korean National Health Insurance Service cohort (adjusted HR, 1.14; 95% CI, 1.07–1.22). Significantly elevated risk of SPM was still observed when considering a 2-year latency period (adjusted HR, 2.43; 95% CI, 1.37–4.48) and a 3-year latency period (adjusted HR, 2.17; 95% CI, 1.06–4.47). Frequent abdominopelvic CT scans are associated with an elevated risk of SPMs after the treatment of EGC. Thus, physicians need to weigh carefully the clinical benefits of CT examinations against the potential risks of radiation exposure.

A pilot study on lung cancer detection based on regional metabolic activity distribution in digital low-dose 18F-FDG PET

OBJECTIVES

To investigate the potential of automatic lung cancer detection on submillisievert dose ¹⁸F-fludeoxyglucose (¹⁸F-FDG) scans using different positron emission tomography (PET) parameters, as a primary step towards a potential new indication for ¹⁸F-FDG PET in lung cancer screening.

METHODS

We performed a retrospective cohort analysis with 83 patients referred for ¹⁸F-FDG PET/CT, including of 34 patients with histology-proven lung cancer and 49 patients without lung disease. Aside clinical standard PET images (PET_100%) two additional low-dose PET reconstructions were generated, using only 15 s and 5 s of the 150 s list mode raw data of the full-dose PET, corresponding to 10% and 3.3% of the original ¹⁸F-FDG activity. The lungs were subdivided into three segments on each side, and each segment was classified as normal or containing cancer. The following standardized uptake values (SUVs) were extracted from PET per lung segment: SUV_mean, SUV_hot5, SUV_median, SUV_std and SUV_total. A multivariate linear regression model was used and cross-validated. The accuracy for lung cancer detection was tested with receiver operating characteristics analysis and T-statistics was used to calculate the weight of each parameter.

RESULTS

The T-statistics showed that SUV_std was the most important discriminative factor for lung cancer detection. The multivariate model achieved an area under the curve of 0.97 for full-dose PET, 0.85 for PET_10% with PET_3.3% reconstructions resulting in a still high sensitivity the PET_10% reconstruction of 80%.

CONCLUSION

This pilot study indicates that segment-based, quantitative PET parameters of low-dose PET reconstructions could be used to automatically detect lung cancer with high sensitivity.

ADVANCES IN KNOWLEDGE

Automated assessment of PET parameters in low-dose PET may aid for an early detection of lung cancer.

Third-generation iterative reconstruction on a dual-source, high-pitch, low-dose chest CT protocol with tin filter for spectral shaping at 100 kV: a study on a small series of COVID-19 patients

OBJECTIVES

To investigate the role of third-generation iterative reconstruction (ADMIRE) in dual-source, high-pitch chest CT protocol with spectral shaping at 100 kVp in Coronavirus disease 2019 (COVID-19).

METHODS

Confirmed COVID-19 inpatients undergoing to unenhanced chest CT were scanned with a dual-energy acquisition (DECT, 90/150Sn kV) and a dual-source, high-pitch acquisition with tin-filtered 100 kVp (LDCT). On the DECT with ADMIRE 3 (DECT3) were evaluated the pulmonary findings and their extension (25-point score). Two radiologists in consensus evaluated with 5-point scales the overall image quality, the anatomical structures, and the elementary findings on LDCT reconstructed with filtered backprojection (LDCT0), with ADMIRE 3 (LDCT3) and 5 (LDCT5), and on DECT3. The signal-to-noise ratio (SNR), the body mass index, the exposure times, and the radiation doses were recorded.

RESULTS

Seventy-five patients (57 M/18F; median age: 63 y.o.) were included, with median pulmonary extension of 13/25 points. The imaging findings were detected in proportion comparable to the available literature. The ADMIRE significantly improved the SNR in LDCT (p < 0.00001) with almost no significant differences in overweight patients. The LDCT had median effective dose of 0.39 mSv and acquisition time of 0.71 s with significantly less motion artifacts than DECT (p < 0.00001). The DECT3 and LDCT3 provided the best image quality and depiction of pulmonary anatomy and imaging findings, with significant differences among all the series (p < 0.00001).

CONCLUSION

The LDCT with spectral shaping and ADMIRE3 provided acceptable image quality in the evaluation of patients with COVID-19, with significantly reduced radiation dose and motion artifacts.

Do low dose CT-KUBs really expose patients to more radiation than plain abdominal radiographs?

BACKGROUND

Urolithiasis patients often require frequent urinary tract imaging, leading to high radiation exposure. CT Kidney-Ureter-Bladder (CT-KUB) is the gold standard in urolithiasis detection, however it is thought to harbour significant radiation load. Urologists have therefore utilised abdominal radiographs (XR-KUB) as an alternative, though with markedly lower sensitivity and specificity. We present the first contemporary UK study comparing the effective doses of XR-KUBs with low dose CT-KUBs.

METHOD

Fifty-three patients were retrospectively identified in a single centre who underwent both a XR-KUB and a CT-KUB in 2018. Effective-Dose was measured by converting the recorded 'Dose Area/Length Product' via the International Commission on Radiological Protection formula.

RESULTS

The average effective dose of XR-KUBs and low dose CT-KUBs were 5.10 mSv and 5.31 mSv respectively. Thirty-four percent (18/53) of patients had a XR-KUBs with a higher effective dose than their low dose CT-KUB. Patients with higher Weight, BMI and AP diameter had higher effective doses for both their XR and low dose CT-KUBs. All patients in our study weighing over 92 kg or with a BMI greater than 32 had a XR-KUBs with a higher effective dose than their low dose CT-KUB.

CONCLUSION

This data supports moving away from XR-KUBs for the investigation of urolithiasis, particularly in patients with a high BMI.