Abdominal peer learning: advantages and lessons learned.

In 2017, our tertiary hospital-based imaging practice transitioned from score-based peer review to the peer learning methodology for learning and improvement. In our subspecialized practice, peer learning submissions are reviewed by domain experts, who then provide feedback to individual radiologists, curate cases for group learning sessions, and develop associated improvement initiatives. In this paper, we share lessons learned from our abdominal imaging peer learning submissions with the assumption that trends in our practice likely mimic others', and hope that other practices can avoid future errors and elevate the level of the quality of their own performance. Adoption of a nonjudgmental and efficient method to share peer "learning opportunities" and "great calls" has increased participation in this activity and increased transparency into our practice, thus allowing for visualization of trends in performance. Peer learning allows us to bring our own individual knowledge and practices together for group review in a collegial and safe environment. We learn from each other and decide how to improve together.

Multi-Energy CT Applications: Problem-Solving in Emergency Radiology.

Multi-energy computed tomography is a technology that is being increasingly used in the emergency room (ER) setting and has many applications that can impact patient care, including virtual monoenergetic imaging and material-specific imaging. It is important for radiologists to understand this technology, and how it can be optimally used in the ER setting.

Fast quantitative bone marrow lesion measurement on knee MRI for the assessment of osteoarthritis.

Objective: Knee osteoarthritis (KOA) is a prevalent disease with a high economic and social cost. Magnetic resonance imaging (MRI) can be used to visualize many KOA-related structures including bone marrow lesions (BMLs), which are associated with OA pain. Several semi-automated software methods have been developed to segment BMLs, using manual, labor-intensive methods, which can be costly for large clinical trials and other studies of KOA. The goal of our study was to develop and validate a more efficient method to quantify BML volume on knee MRI scans. Materials and methods: We have applied a deep learning approach using a patch-based convolutional neural network (CNN) which was trained using 673 MRI data sets and the segmented BML masks obtained from a trained reader. Given the location of a BML provided by the reader, the network performed a fully automated segmentation of the BML, removing the need for tedious manual delineation. Accuracy was quantified using the Pearson's correlation coefficient, by a comparison to a second expert reader, and using the Dice Similarity Score (DSC). Results: The Pearson's R2 value was 0.94 and we found similar agreement when comparing two readers (R2 â€‹= â€‹0.85) and each reader versus the DL model (R2 â€‹= â€‹0.95 and R2 â€‹= â€‹0.81). The average DSC was 0.70. Conclusions: We developed and validated a deep learning-based method to segment BMLs on knee MRI data sets. This has the potential to be a valuable tool for future large studies of KOA.

Importance of tumor subtypes in cancer imaging.

Cancer therapy has evolved from being broadly directed towards tumor types, to highly specific treatment protocols that target individual molecular subtypes of tumors. With the ever-increasing data on imaging characteristics of tumor subtypes and advancements in imaging techniques, it is now often possible for radiologists to differentiate tumor subtypes on imaging. Armed with this knowledge, radiologists may be able to provide specific information that can obviate the need for invasive methods to identify tumor subtypes. Different tumor subtypes also differ in their patterns of metastatic spread. Awareness of these differences can direct radiologists to relevant anatomical sites to screen for early metastases that may otherwise be difficult to detect during cursory inspection. Likewise, this knowledge will help radiologists to interpret indeterminate findings in a more specific manner.

MRI features of treated hepatocellular carcinoma following locoregional therapy: a pictorial review.

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide and within the United States. Liver transplant or partial liver resection is the definitive treatment of choice for HCC; however, the majority of cases are detected in advanced stages due to its early-stage asymptomatic nature, often precluding surgical treatment. Locoregional therapy plays an essential role in HCC management, including curative intent, as a bridge to transplant, or in some cases palliative therapy. Radiologists play a critical role in assessing tumor response following treatment to guide further management that may potentially impact transplantation eligibility; therefore, it is important for radiologists to have an understanding of different locoregional therapies and the variations of imaging response to different therapies. In this review article, we outline the imaging response to ablative therapy (AT), transarterial chemoembolization (TACE), selective internal radiation therapy (SIRT), and stereotactic body radiation therapy (SBRT). We will also briefly discuss the basic concepts of these locoregional therapies. This review focuses on the imaging features following locoregional treatment for hepatocellular carcinoma following AT, TACE, SIRT, and SBRT.

External COVID-19 Deep Learning Model Validation on ACR AI-LAB: It's a Brave New World.

PURPOSE: Deploying external artificial intelligence (AI) models locally can be logistically challenging. We aimed to use the ACR AI-LAB software platform for local testing of a chest radiograph (CXR) algorithm for COVID-19 lung disease severity assessment. METHODS: An externally developed deep learning model for COVID-19 radiographic lung disease severity assessment was loaded into the AI-LAB platform at an independent academic medical center, which was separate from the institution in which the model was trained. The data set consisted of CXR images from 141 patients with reverse transcription-polymerase chain reaction-confirmed COVID-19, which were routed to AI-LAB for model inference. The model calculated a Pulmonary X-ray Severity (PXS) score for each image. This score was correlated with the average of a radiologist-based assessment of severity, the modified Radiographic Assessment of Lung Edema score, independently interpreted by three radiologists. The associations between the PXS score and patient admission and intubation or death were assessed. RESULTS: The PXS score deployed in AI-LAB correlated with the radiologist-determined modified Radiographic Assessment of Lung Edema score (r = 0.80). PXS score was significantly higher in patients who were admitted (4.0 versus 1.3, P < .001) or intubated or died within 3 days (5.5 versus 3.3, P = .001). CONCLUSIONS: AI-LAB was successfully used to test an external COVID-19 CXR AI algorithm on local data with relative ease, showing generalizability of the PXS score model. For AI models to scale and be clinically useful, software tools that facilitate the local testing process, like the freely available AI-LAB, will be important to cross the AI implementation gap in health care systems.

Teaching cancer imaging in the era of precision medicine: Looking at the big picture.

The role of imaging in cancer diagnosis and treatment has evolved at the same rapid pace as cancer management. Over the last twenty years, with the advancement of technology, oncology has become a multidisciplinary field that allows for researchers and clinicians not only to create individualized treatment options for cancer patients, but also to evaluate patients' response to therapy with increasing precision. Familiarity with these concepts is a requisite for current and future radiologists, as cancer imaging studies represent a significant and growing component of any radiology practice, from tertiary cancer centers to community hospitals. In this review we provide the framework to teach cancer imaging in the era of genomic oncology. After reading this article, readers should be able to illustrate the basics cancer genomics, modern cancer genomics, to summarize the types of systemic oncologic therapies available, their patterns of response and their adverse events, to discuss the role of imaging in oncologic clinical trials and the role of tumor response criteria and to display the future directions of oncologic imaging.

Virtual Monoenergetic Spectral Detector CT for Preoperative CT Angiography in Liver Donors.

OBJECTIVE: The purpose of this study was to evaluate the use of virtual monoenergetic images (VMI) in pre-operative CT angiography of potential donors for living donor adult liver transplantation (LDALT), and to determine the optimal energy level to maximize vascular signal-to-noise and contrast-to-noise ratios (SNR and CNR, respectively). MATERIALS AND METHODS: We retrospectively evaluated 29 CT angiography studies performed preoperatively in potential liver donors on a spectral detector CT scanner. All studies included arterial, early venous, and delayed venous phase imaging. Conventional polyenergetic images were generated for each patient, as well as virtual monoenergetic images in 10 keV increments from 40 -100 keV. Arteries (aorta and celiac, superior mesenteric, common hepatic, right and left hepatic arteries) were assessed on arterial phase images; portal venous system branches (splenic, superior mesenteric, main, right, and left portal veins) on early venous phase images; and hepatic veins on late venous phase images. Vascular attenuation, background parenchymal attenuation, and noise were measured on each set of virtual monoenergetic and conventional images. RESULTS: Background hepatic and vascular noise decreased with increasing keV, with the lowest noise at 100 keV. Vascular SNR and CNR increased with decreasing keV and were highest at 40 keV, with statistical significance compared with conventional ( P < 0.05). CONCLUSIONS: In preoperative CT angiography for potential liver donors, the optimal keV for assessing the vasculature to improve SNR and CNR is 40 keV. Use of low keV VMI in LDALT CT protocols may facilitate detection of vascular anatomical variants that can impact surgical planning.

Spectral detector CT applications in advanced liver imaging.

OBJECTIVE: Spectral detector CT (SDCT) has many applications in advanced liver imaging. If appropriately utilized, this technology has the potential to improve image quality, provide new diagnostic information, and allow for decreased radiation dose. The purpose of this review is to familiarize radiologists with the uses of SDCT in liver imaging. CONCLUSION: SDCT has a variety of post-processing techniques, which can be used in advanced liver imaging and can significantly add value in clinical practice.

Dual energy CT in clinical routine: how it works and how it adds value.

Dual energy computed tomography (DECT), also known as spectral CT, refers to advanced CT technology that separately acquires high and low energy X-ray data to enable material characterization applications for substances that exhibit different energy-dependent x-ray absorption behavior. DECT supports a variety of post-processing applications that add value in routine clinical CT imaging, including material selective and virtual non-contrast images using two- and three-material decomposition algorithms, virtual monoenergetic imaging, and other material characterization techniques. Following a review of acquisition and post-processing techniques, we present a case-based approach to highlight the added value of DECT in common clinical scenarios. These scenarios include improved lesion detection, improved lesion characterization, improved ease of interpretation, improved prognostication, inherently more robust imaging protocols to account for unexpected pathology or suboptimal contrast opacification, length of stay reduction, reduced utilization by avoiding unnecessary follow-up examinations, and radiation dose reduction. A brief discussion of post-processing workflow approaches, challenges, and solutions is also included.

Dual-energy CT for routine imaging of the abdomen and pelvis: radiation dose and image quality.

PURPOSE: To assess the radiation dose and image quality of routine dual energy CT (DECT) of the abdomen and pelvis performed in the emergency department setting, compared with single energy CT (SECT). MATERIALS AND METHODS: Seventy-five consecutive routine contrast-enhanced SECT scans of the abdomen and pelvis meeting inclusion criteria were compared with 75 routine contrast-enhanced DECT scans matched by size and patient weight (within 10 lbs), performed on the same dual-source DECT scanner. Cohorts were compared in terms of radiation dose metrics of CT dose index (CTDIvol) and dose length product (DLP), objective measurements of image quality (signal, noise, and signal-to-noise ratio of a variety of anatomical landmarks), and subjective measurements of image quality scored by two emergency radiologists. RESULTS: Demographics and patient size were not statistically different between DECT and SECT cohorts. Both average scans CTDIvol and DLP were significantly lower with DECT than with SECT. Average scan CTDIvol for SECT was 14.7 mGy (± 6.6) and for DECT was 10.9 mGy (± 3.8) (p < 0.0001). Average scan DLP for SECT was 681.5 mGy cm (± 339.3) and for DECT was 534.8 mGy cm (± 201.9) (p < 0.0001). For objective image quality metrics, for all structures measured, noise was significantly lower and SNR was significantly higher with DECT compared with SECT. For subjective image quality, for both readers, there was no significant difference between SECT and DECT in subjective image quality for soft tissues and vascular structures, or for subjective image noise. CONCLUSIONS: DECT was performed with decreased radiation dose when compared with SECT, demonstrated improved objective measurements of image quality, and equivalent subjective image quality.

Virtual monoenergetic dual-energy CT for evaluation of hepatic and splenic lacerations.

PURPOSE: To evaluate the utility of virtual monoenergetic imaging in assessing hepatic and splenic lacerations and to determine the optimal energy level to maximize injury contrast-to-noise ratio. METHODS: We retrospectively examined 49 contrast-enhanced abdominal CT studies performed on a dual-source dual-energy CT (DECT) scanner with reported liver and/or splenic lacerations. All studies included portal venous phase imaging acquired simultaneously at low (80 or 100 kVp) and high (140 kVp with tin filtration) energy levels. Conventional 120 kVp-equivalent images were generated for routine review by blending the low and high energy acquisitions. Virtual monoenergetic reconstructions were retrospectively generated in 10 keV increments from 40 to 90 keV. Liver or splenic laceration attenuation, background parenchymal attenuation, and noise were measured on each set of monoenergetic and conventional images. Injury-to-parenchyma contrast and contrast-to-noise ratios (CNR) were calculated. Differences between CNR of monoenergetic series and conventional images were assessed with a paired t test. RESULTS: Liver laceration was identified in 28 patients, and splenic laceration in 22 patients. Background noise was lower at higher monoenergetic levels, with the lowest noise seen at 90 keV, less than that of conventional images (stddev 8.0 for 90 keV and 8.5 for conventional based on noise of uninjured liver/spleen parenchyma, p < 0.001). For both liver and splenic lacerations, injury-to-parenchyma contrast was greater at lower monoenergetic levels, with maximum at 40 keV. Contrast at 40-70 keV was significantly greater than that of conventional images (p < 0.001). Injury-to parenchyma CNR was also greater at 40-70 keV than that of conventional images and with statistical significance. CNR was highest at 40 keV for both liver (6.5 for 40 keV and 5.4 for conventional, p < 0.001) and splenic lacerations (7.5 vs. 5.8, p < 0.001). CONCLUSIONS: DECT virtual monoenergetic imaging at low keV improves injury-to-parenchyma CNR of hepatic and splenic lacerations compared with traditional polyenergetic reconstructions. Specially, the optimal energy level for assessing both was 40 keV.

Beyond appendicitis: ultrasound findings of acute bowel pathology.

Bowel pathology is a common unexpected finding on routine abdominal and pelvic ultrasound. However, radiologists are often unfamiliar with the ultrasound appearance of the gastrointestinal tract due to the underutilization of ultrasound for bowel evaluation in the USA. The purpose of this article is to familiarize radiologists with the characteristic ultrasound features of a variety of bowel pathologies. Basic ultrasound technique for bowel evaluation, ultrasound appearance of normal bowel, and key ultrasound features of common acute bowel abnormalities will be reviewed.

Impact Analysis of the Routine Use of Dual-Energy Computed Tomography for Characterization of Incidental Renal Lesions.

OBJECTIVE: The aim of this study was to quantify the prevalence of incidental, indeterminate renal lesions on routine contrast-enhanced abdominal computed tomography (CT) and the proportion of such lesions that could be exonerated by dual-energy CT (DECT) postprocessing as benign hyperdense cysts. METHODS: The reports for 2729 consecutive contrast-enhanced DECT scans in the emergency department setting were reviewed for the mention of any renal lesion. For scans with a reported lesion, images were reviewed to assess for the presence of an indeterminate lesion that could not be definitively characterized as benign. All indeterminate lesions were reviewed with DECT postprocessing by 2 radiologists to assess for enhancement and other imaging characteristics and characterized by readers as benign or not definitively benign. Agreement between readers was assessed statistically, and disagreement was resolved by consensus. RESULTS: Two thousand seven hundred twenty-nine scans were performed in 2406 unique patients; a renal lesion was reported in 805 unique patient scans (33.4%). Review of these 805 scans led to discovery of 137 indeterminate lesions in 125 scans (5.2% of patients). Of the 137 lesions, 70 (51.1%) were classified as benign hyperdense cysts by readers, with the remaining 67 lesions classified as not definitively benign (43 solid masses, 9 Bosniak IIF cysts, 8 Bosniak III cysts, 7 Bosniak IV cysts). CONCLUSIONS: Incidental indeterminate renal lesions are common on routine contrast-enhanced CT. More than half of these lesions could potentially be exonerated with DECT as benign Bosniak II cysts, which could avert the need for further workup in 2.8% of patients undergoing routine abdominal CT.

Pearls, Pitfalls, and Problems in Dual-Energy Computed Tomography Imaging of the Body.

Dual-energy computed tomography (DECT) is an exciting technology that is increasing in routine use and has the potential for significant clinical impact. With the advancement of DECT, it is important for radiologists to be aware of potential challenges with DECT acquisition and postprocessing, and to have a basic knowledge of unique artifacts and diagnostic pitfalls that can occur when interpreting DECT scans and DECT postprocessed images. This article serves as a practical overview of potential problems and diagnostic pitfalls associated with DECT, and steps that can be taken to avoid them.

Dual energy CT for evaluation of polycystic kidneys: a multi reader study of interpretation time and diagnostic confidence.

PURPOSE: To compare dual-energy CT (DECT) iodine overlay images with renal mass protocol CT in the evaluation of polycystic kidneys with respect to reading time, diagnostic confidence, and detection of renal lesions that are not definitively benign. METHODS: Following IRB approval, portal venous phase dual-source DECT scans performed between September 2013 and February 2016 from 55 patients (mean age 67 ± 15 years, 31 male, 24 female) with polycystic kidneys (4 or more cysts) were included. For each patient, two image sets were created: (1) DECT post-processed iodine overlay images and (2) simulated renal mass protocol CT images (virtual noncontrast and mixed images). Two radiologists independently retrospectively reviewed both sets at separate time points, evaluating for the presence of lesions that were not definitively benign (enhancing lesions or Bosniak IIF cysts), as well as reading times and Likert scale diagnostic confidence ratings (scaled 1-5) for the presence of non-benign lesions. Reading times were compared with a t test, diagnostic confidence with a McNemar test, and lesion number detection with Cohen's kappa test. RESULTS: Iodine overlay images were read faster (mean 55 ± 26 s) than renal mass protocol (mean 105 ± 51 s) (p < 0.001). Readers assigned the highest diagnostic confidence rating in 64% using iodine overlay series, compared to 17% using renal mass protocol (p < 0.0001). The proportion of patients with recorded lesions was not significantly different between methods (p = 0.62). CONCLUSIONS: DECT improves lesion assessment in polycystic kidneys by decreasing reading times and increasing diagnostic confidence, without affecting lesion detection rates.

Imaging of Acute Conditions of the Perineum.

A wide range of acute conditions can affect the perineum, from self-limited disease to conditions that are potentially life threatening or contribute to substantial patient morbidity if not promptly diagnosed and appropriately treated. Imaging is essential in the clinical management of perineal disease because it allows accurate anatomic localization of the origin and extent of the disease to be determined. Familiarity with complex perineal anatomy, appropriate use of imaging modalities, and the spectrum of imaging findings seen in acute perineal conditions is crucial for radiologists to make a rapid and accurate diagnosis. Various imaging modalities are available to evaluate acute perineal conditions, each with their own advantages and disadvantages. Computed tomography is used most commonly in the acute care setting because of its widespread availability and rapid image acquisition. Ultrasonography could be used to evaluate superficial and palpable abnormalities and is especially helpful for diagnosis of genital injuries. Magnetic resonance (MR) imaging exhibits superior tissue contrast resolution, provides excellent characterization of conditions, and lacks ionizing radiation. Its role is increasing in the acute care setting; however, MR imaging is not always readily available and is currently reserved for use as a problem-solving technique. Retrograde urethrography is the modality of choice for evaluating traumatic urethral injury. ©RSNA, 2018.

Motion Artifact Reduction From High-Pitch Dual-Source Computed Tomography Pulmonary Angiography.

PURPOSE: The purpose of this study was to compare quantitative and qualitative measures of aortic, cardiac, and respiratory motion artifact between high-pitch dual-source (DS) and single-source (SS) computed tomography pulmonary angiography (CTPA) protocols. METHODS: This institutional review board-approved, Health Insurance Portability and Accountability Act-compliant study retrospectively reviewed 80 non-electrocardiogram-gated CTPA examinations acquired with a second-generation DS system at 100 kVp following 50 mL iodinated contrast injection - 40 consecutive SS and 40 consecutive DS studies. Quantitative measures of aortic, left ventricular, and diaphragmatic motion were recorded as the maximal excursion of a structure's "double image," and 3 independent readers performed qualitative motion assessments. Pulmonary arterial contrast enhancement, image noise, and radiation dose metrics were recorded. Statistical analyses were performed with 1-way analysis of variance and Fisher exact test. RESULTS: Dual source outperformed SS technique in both quantitative and qualitative measures of motion. Mean distances between motion-artifact double images were reduced with DS protocol at each location (all P ≤ 0.004), and DS examinations were more likely to receive an assessment of no motion in all locations (all P < 0.0001). The DS protocol demonstrated increases in contrast enhancement, although increased image noise resulted in lower enhancement to noise ratio. Mean radiation dose was 60% lower using the DS protocol. CONCLUSION: High-pitch DS CTPA significantly reduces artifacts resulting from ascending aortic, cardiac, and diaphragmatic motion.