Radiology of fibrosis part III: genitourinary system.

Fibrosis is a pathological process involving the abnormal deposition of connective tissue, resulting from improper tissue repair in response to sustained injury caused by hypoxia, infection, or physical damage. It can impact any organ, leading to their dysfunction and eventual failure. Additionally, tissue fibrosis plays an important role in carcinogenesis and the progression of cancer.Early and accurate diagnosis of organ fibrosis, coupled with regular surveillance, is essential for timely disease-modifying interventions, ultimately reducing mortality and enhancing quality of life. While extensive research has already been carried out on the topics of aberrant wound healing and fibrogenesis, we lack a thorough understanding of how their relationship reveals itself through modern imaging techniques.This paper focuses on fibrosis of the genito-urinary system, detailing relevant imaging technologies used for its detection and exploring future directions.

Radiology of fibrosis. Part I: Thoracic organs.

Sustained injury from factors such as hypoxia, infection, or physical damage may provoke improper tissue repair and the anomalous deposition of connective tissue that causes fibrosis. This phenomenon may take place in any organ, ultimately leading to their dysfunction and eventual failure. Tissue fibrosis has also been found to be central in both the process of carcinogenesis and cancer progression. Thus, its prompt diagnosis and regular monitoring is necessary for implementing effective disease-modifying interventions aiming to reduce mortality and improve overall quality of life. While significant research has been conducted on these subjects, a comprehensive understanding of how their relationship manifests through modern imaging techniques remains to be established. This work intends to provide a comprehensive overview of imaging technologies relevant to the detection of fibrosis affecting thoracic organs as well as to explore potential future advancements in this field.

Radiology of fibrosis part II: abdominal organs.

Fibrosis is the aberrant process of connective tissue deposition from abnormal tissue repair in response to sustained tissue injury caused by hypoxia, infection, or physical damage. It can affect almost all organs in the body causing dysfunction and ultimate organ failure. Tissue fibrosis also plays a vital role in carcinogenesis and cancer progression. The early and accurate diagnosis of organ fibrosis along with adequate surveillance are helpful to implement early disease-modifying interventions, important to reduce mortality and improve quality of life. While extensive research has already been carried out on the topic, a thorough understanding of how this relationship reveals itself using modern imaging techniques has yet to be established. This work outlines the ways in which fibrosis shows up in abdominal organs and has listed the most relevant imaging technologies employed for its detection. New imaging technologies and developments are discussed along with their promising applications in the early detection of organ fibrosis.

Innovative standardized reporting template for prostate mpMRI improves clarity and confidence in the report.

PURPOSE: The goal of the current study was to evaluate the effect of a standardized prostate mpMRI reporting template on urologists' understanding and confidence in counselling a patient on the results of the MRI. To do this we performed a survey study to assess the understanding and confidence of urologists reviewing reports prior to (pre) and after (post) adoption of a standardized mpMRI template. METHODS: Six urologists reviewed ten pre- and post- mpMRI templated reports and completed a survey to assess the clarity of key elements and the confidence in counseling the patient. The urologists were blinded to the study objective. Nonparametric constrained permutation test for significance was performed to compare the results prior to and after implementation of the template. RESULTS: 29 pre- and 30 post-template mpMRI reports were reviewed. The average score for the post-template reports was significantly higher (10.7 ± 0.6 vs 7.5 ± 2.7 [ p< 0.001]) regardless of the reviewer. Urologists were also overall more confident in counselling patients when the standardized mpMRI reporting template had been used. CONCLUSION: Implementation of a standardized template for reporting of prostate mpMRI findings resulted in improved clarity and confidence in counselling patients. Radiologists should consider implementing a standardized reporting template to improve clinicians' understanding and confidence of the report.

Impact of mandated prospectively reported apparent diffusion coefficient values on the rates of positivity for clinically significant prostate cancer by PI-RADS score.

BACKGROUND: Prior research has shown that retrospectively measured apparent diffusion coefficient (ADC) of prostate magnetic resonance imaging (MRI) lesions is associated with clinically significant prostate cancer (csPCa) on targeted biopsy suggesting that ADC should be measured and reported prospectively. PURPOSE: To assess the impact of mandatory prospective measurement of ADC on the rates of positivity across PI-RADS scores for csPCa. MATERIAL AND METHODS: Consecutive patients who underwent ultrasound (US)-MRI fusion prostate biopsy from August 2018 to July 2019 and who had prospectively reported ADC were compared to control patients who did not. Rates of positivity by PI-RADS category were computed and compared using Chi-square. Multivariable regression was performed. RESULTS: In total, 126 patients (median age 65 years) with 165 prostate lesions (19, 51, 70, and 25 PI-RADS 2, 3, 4, and 5, respectively) and prospectively reported ADC values were compared to 113 control patients (median age 66 years) with 157 prostate lesions (17, 42, 64, and 34 PI-RADS 2, 3, 4, and 5, respectively). Rates of positivity across PI-RADS scores were similar between the two cohorts; 11%, 25%, 55%, and 76% and 0%, 21%, 56%, and 62% for PI-RADS 2, 3, 4, and 5 in the test and control cohorts, respectively (Chi-square P = 0.78). Multivariate logistic regression showed no significant association between the presence of prospectively measured ADC and csPCa (odds ratio 1.1, 95% confidence interval 0.7-1.7, P = 0.82). CONCLUSION: Prospective ADC measurement may not impact PI-RADS category assignments or positivity rates for csPCa under current guidelines. Future versions of PI-RADS may need to incorporate ADC into scoring rules to realize their potential.

3D Isotropic Super-resolution Prostate MRI Using Generative Adversarial Networks and Unpaired Multiplane Slices.

We developed a deep learning-based super-resolution model for prostate MRI. 2D T2-weighted turbo spin echo (T2w-TSE) images are the core anatomical sequences in a multiparametric MRI (mpMRI) protocol. These images have coarse through-plane resolution, are non-isotropic, and have long acquisition times (approximately 10-15 min). The model we developed aims to preserve high-frequency details that are normally lost after 3D reconstruction. We propose a novel framework for generating isotropic volumes using generative adversarial networks (GAN) from anisotropic 2D T2w-TSE and single-shot fast spin echo (ssFSE) images. The CycleGAN model used in this study allows the unpaired dataset mapping to reconstruct super-resolution (SR) volumes. Fivefold cross-validation was performed. The improvements from patch-to-volume reconstruction (PVR) to SR are 80.17%, 63.77%, and 186% for perceptual index (PI), RMSE, and SSIM, respectively; the improvements from slice-to-volume reconstruction (SVR) to SR are 72.41%, 17.44%, and 7.5% for PI, RMSE, and SSIM, respectively. Five ssFSE cases were used to test for generalizability; the perceptual quality of SR images surpasses the in-plane ssFSE images by 37.5%, with 3.26% improvement in SSIM and a higher RMSE by 7.92%. SR images were quantitatively assessed with radiologist Likert scores. Our isotropic SR volumes are able to reproduce high-frequency detail, maintaining comparable image quality to in-plane TSE images in all planes without sacrificing perceptual accuracy. The SR reconstruction networks were also successfully applied to the ssFSE images, demonstrating that high-quality isotropic volume achieved from ultra-fast acquisition is feasible.

Making sense of the CT Urogram.

KEY POINTS: • There is great variation in the CT urogram protocol throughout the literature. • The study by Renard-Penna et al provides a useful rigorous expert consensus on CT urography technique. • The study by Rud et al suggests that the excretory phase may not be as necessary as previously thought for visualizing upper tract urothelial carcinoma.

Radiomics of MRI for pretreatment prediction of pathologic complete response, tumor regression grade, and neoadjuvant rectal score in patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiation: an international multicenter study.

OBJECTIVE: To investigate whether pretreatment MRI-based radiomics of locally advanced rectal cancer (LARC) and/or the surrounding mesorectal compartment (MC) can predict pathologic complete response (pCR), neoadjuvant rectal (NAR) score, and tumor regression grade (TRG). METHODS: One hundred thirty-two consecutive patients with LARC who underwent neoadjuvant chemoradiation and total mesorectal excision (TME) were retrospectively collected from 2 centers in the USA and Italy. The primary tumor and surrounding MC were segmented on the best available T2-weighted sequence (axial, coronal, or sagittal). Three thousand one hundred ninety radiomic features were extracted using a python package. The most salient radiomic features as well as MRI parameter and clinical-based features were selected using recursive feature elimination. A logistic regression classifier was built to distinguish between any 2 binned categories in the considered endpoints: pCR, NAR, and TRG. Repeated k-fold validation was performed and AUCs calculated. RESULTS: There were 24, 87, and 21 T4, T3, and T2 LARCs, respectively (median age 63 years, 32 to 86). For NAR and TRG, the best classification performance was obtained using both the tumor and MC segmentations. The AUCs for classifying NAR 0 versus 2, pCR, and TRG 0/1 versus 2/3 were 0.66 (95% CI, 0.60-0.71), 0.80 (95% CI, 0.74-0.85), and 0.80 (95% CI, 0.77-0.82), respectively. CONCLUSION: Radiomics of pretreatment MRIs can predict pCR, TRG, and NAR score in patients with LARC undergoing neoadjuvant treatment and TME with moderate accuracy despite extremely heterogenous image data. Both the tumor and MC contain important prognostic information. KEY POINTS: • Machine learning of rectal cancer on images from the pretreatment MRI can predict important patient outcomes with moderate accuracy. • The tumor and the tissue around it both contain important prognostic information.

The Negative Predictive Value of a PI-RADS Version 2 Score of 1 on Prostate MRI and the Factors Associated With a False-Negative MRI Study.

OBJECTIVE. The purpose of this study was to calculate the negative predictive value of a prostate MRI study with a Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) score of 1 (hereafter referred to as a PI-RADS 1 MRI study) and to explore the patient characteristics and MRI-based factors associated with an MRI study with false-negative results. MATERIALS AND METHODS. A total of 542 consecutive patients with a PI-RADS 1 MRI study obtained between January 2016 and July 2019 were retrospectively identified. Patient charts were examined to identify those patients who subsequently underwent systematic prostate biopsy within 1 year of undergoing MRI or at any later date if the biopsy was negative. Patient characteristics and MRI-specific factors were recorded. Two blinded radiologists evaluated the quality of the axial T2-weighted, DWI, and apparent diffusion coefficient sequences; measured the volume of the bladder, the prostate gland, and rectal gas; and determined whether the peripheral zone was avidly enhancing and whether low signal intensity was seen in 50% or more of the peripheral zone on T2-weighted images. Interobserver agreement was tested. Univariable and multivariable logistic regression models were built. RESULTS. A total of 150 patients (median age, 63 years; interquartile range, 56-70 years) were included. Of these patients, 19 (13%) had prostate cancer with a Gleason score of 3 + 4 or greater, yielding a negative predictive value of 87%. Both low T2 signal intensity in the peripheral zone and the prostate-specific antigen level were associated with a false-negative PI-RADS 1 assessment (odds ratio, 4.9 [95% CI, 1.6-14.9; p = 0.006] and 1.1 [95% CI, 1.0-1.2; p = 0.03], respectively). A cutoff prostate-specific antigen level of 3.97 ng/mL resulted in sensitivity and specificity of 89% and 21%, respectively. There was moderate interobserver agreement for low T2 signal intensity in the peripheral zone (κ coefficient = 0.75). CONCLUSION. Even among select patients who undergo subsequent biopsy because of a high clinical suspicion of prostate cancer, a PI-RADS 1 prostate MRI study has a high negative predictive value. A T2-hypointense peripheral zone and an elevated prostate-specific antigen level are significantly associated with a false-negative MRI study.

Active Surveillance of Small (< 4 cm) Bosniak Category 2F, 3, and 4 Renal Lesions: What Happens on Imaging Follow-Up?

OBJECTIVE. The purpose of this study was to determine the percentage of small (< 4 cm) Bosniak category 2F, 3, and 4 lesions that regress during active surveillance. MATERIALS AND METHODS. In this retrospective study, a hospital database was searched from January 1, 2005, through September 9, 2017, for small (< 4 cm) Bosniak category 2F, 3, and 4 lesions studied with initial and follow-up unenhanced and contrast-enhanced CT or MRI. Prospective Bosniak categories were recorded. Two blinded radiologists retrospectively reassigned Bosniak categories to the initial and last follow-up studies. Interreader variability was analyzed. Rates of stability, regression, and progression were calculated and stratified by size. Logistic regression was used to assess the effects of lesion size, lesion growth, and duration of follow-up on the change in Bosniak categories. RESULTS. The search identified 123 patients (85 men, 38 women) with 138 renal lesions (according to the blinded readings, 83 Bosniak category 2F, 37 category 3, and 18 category 4) and followed for 1-12.3 years (median, 2.7 years). Fifty-one percent (70/138) of the lesions were smaller than 2 cm. Eighty-eight percent (73/83) of category 2F lesions were downgraded or remained stable. Forty-five percent (25/55) of category 3 or 4 lesions were downgraded to 2F or lower. Kappa values were 0.94 between the two readers and 0.72-0.76 between the readers and the prospective Bosniak categories. There was no association between initial size, change in size, or duration of follow-up and change in Bosniak category. CONCLUSION. Approximately one-half of small (< 4 cm) Bosniak category 3 and 4 cystic renal lesions were downgraded, and the majority (88%) of small Bosniak category 2F lesions regressed or remained stable during active surveillance. Therefore, small size should be a consideration for conservative management.

Prediction of Lymph Node Maximum Standardized Uptake Value in Patients With Cancer Using a 3D Convolutional Neural Network: A Proof-of-Concept Study.

OBJECTIVE: The purpose of this study is to determine whether a convolutional neural network (CNN) can predict the maximum standardized uptake value (SUVmax) of lymph nodes in patients with cancer using the unenhanced CT images from a PET/CT examination, thus providing a proof of concept for potentially using deep learning to diagnose nodal involvement. MATERIALS AND METHODS: Consecutive initial staging PET/CT scans obtained in 2017 for patients with pathologically proven malignancy were collected. Two blinded radiologists selected one to 10 lymph nodes from the unenhanced CT portion of each PET/CT examination. The SUVmax of the lymph nodes was recorded. Lymph nodes were cropped and used with the primary tumor histology type as input for a novel 3D CNN with predicted SUVmax as the output. The CNN was trained using one cohort and tested using a separate cohort. An SUVmax of 2.5 or greater was defined as FDG avid. Two blinded radiologists separately classified lymph nodes as FDG avid or not FDG avid on the basis of unenhanced CT images and separately using a short-axis measurement cutoff of 1 cm. Logistic regression analysis was performed. RESULTS: A total of 400 lymph nodes (median SUVmax, 6.8 [interquartile range {IQR}, 2.7-11.6]; median short-axis, 1.1 cm [IQR, 0.9-1.6 cm]) in 136 patients were used for training. A total of 164 lymph nodes (median SUVmax, 3.5 [IQR, 1.9-8.6]; median short-axis, 1.0 cm [IQR, 0.7-1.4 cm]) in 49 patients were used for testing. The predicted SUVmax was associated with the real SUVmax (ß estimate = 0.83, p < 0.0001). The predicted SUVmax was associated with FDG avidity (p < 0.0001), with an ROC AUC value of 0.85, and it improved when combined with radiologist qualitative assessment and short-axis criteria. CONCLUSION: A CNN is able to predict with moderate accuracy the SUVmax of lymph nodes, as determined from the unenhanced CT images and tumor histology subtype for patients with cancer.

Diffuse Peripheral Zone T2 Hypointensity: When to Worry About Prostate Cancer.

OBJECTIVE: Evaluate the accuracy of an obscured surgical capsule (OSC) for detecting diffuse prostate cancer (PCa) in the setting of diffusely T2 hypointense peripheral zones (PZs) on prostate magnetic resonance imaging. METHODS: Axial T2-weighted sequences of prostate magnetic resonance imaging performed on July 1, 2015, to August 1, 2017, were blindly assessed for diffusely T2 hypointense PZs, OSC, and focal diffusion abnormalities by 2 radiologists. Diffuse PCa was defined by the presence of bilateral PCa on at least 4 contiguous biopsy cores involving 2/3 levels. Interobserver agreement and multivariate analysis were performed. RESULTS: Seven (10%) of 70 patients had diffuse PCa. There was weak interreader agreement for OSC (κ coefficient = 0.58). Obscured surgical capsule was 57% sensitive and 89% specific for the presence of diffuse PCa and was associated with it (odds ratio, 17.6; P = 0.0008). Multivariate logistic regression demonstrated that OSC was the only significant predictor for the presence of diffuse PCa. CONCLUSION: Obscured surgical capsule is a strong independent predictor for diffuse PCa in T2 hypointense PZs.

Bosniak IIF and III Renal Cysts: Can Apparent Diffusion Coefficient-Derived Texture Features Discriminate Between Malignant and Benign IIF and III Cysts?

OBJECTIVE: The aim of this study was to determine which apparent diffusion coefficient-derived texture features are associated with malignancy in Bosniak IIF and III renal cystic lesions. METHODS: Twenty benign and 7 malignant Bosniak IIF (22) or III (5) renal cysts, as evaluated with magnetic resonance imaging, were assessed for progression to pathology-confirmed malignancy. Whole-cyst volumes of interest were manually segmented from apparent diffusion coefficient maps. Texture features were extracted from each volume of interest, including first-order histogram-based features and higher-order features, and data were analyzed with the Mann-Whitney U test to predict malignant progression. RESULTS: Eleven of 17 first-order features were significantly greater in benign compared with malignant cysts. Eight higher-order gray-level co-occurrence matrix (GLCM) texture features were significantly different between groups, 5 of which were greater in the benign population. CONCLUSIONS: Apparent diffusion coefficient-derived texture measures may help differentiate between benign and malignant Bosniak IIF and III cysts.

Nonenhancing Component of Clear Cell Renal Cell Carcinoma on Computed Tomography Correlates With Tumor Necrosis and Stage and Serves as a Size-Independent Prognostic Biomarker.

OBJECTIVES: This study aimed to quantify nonenhancing tumor (NT) component in clear cell renal cell carcinoma (ccRCC) and assess its association with histologically defined tumor necrosis, stage, and survival outcomes. METHODS: Among 183 patients with ccRCC, multi-institutional changes in computed tomography attenuation of tumor voxels were used to quantify percent of NT. Associations of NT with histologic tumor necrosis and tumor stage/grade were tested using Wilcoxon signed rank test and with survival outcomes using Kaplan-Meier curves/Cox regression analysis. RESULTS: Nonenhancing tumor was higher in ccRCC with tumor necrosis (11% vs 7%; P = 0.040) and higher pathological stage (P = 0.042 and P < 0.001, respectively). Patients with greater NT had higher incidence of cancer recurrence after resection (P < 0.001) and cancer-specific mortality (P < 0.001). CONCLUSION: Nonenhancing tumor on preoperative computed tomographic scans in patients with ccRCC correlates with tumor necrosis and stage and may serve as an independent imaging prognostic biomarker for cancer recurrence and cancer-specific survival.

'It's all foreign to me': how to decipher gastrointestinal intraluminal foreign bodies.

In evaluating the gastrointestinal tract, whether in the emergency room setting, the inpatient setting or the outpatient setting, the radiologist may encounter a myriad of intraluminal radio-opaque, non-anatomic entities. It is the radiologist's role to distinguish between true foreign bodies and medical paraphernalia. Further, the later must be evaluated for proper positioning vs. improper, potentially detrimental positioning. While many foreign bodies from the community may be distinctly familiar to the radiologist, the large variety of medical tools in existence may not be. Furthermore, many medical devices are designed to transiently traverse, or interact with the gastrointestinal tract, requiring the radiologist to become familiar with their natural history. We explore a select group of common and uncommon intraluminal foreign bodies and will divide them into medical paraphernalia that are properly positioned; medical paraphernalia that are in abnormal locations and miscellaneous foreign bodies from the community. For each medical tool, we will discuss its development and medical utility, natural history as it relates to the gastrointestinal tract, optimal positioning as assessed radiologically, malpositioning, and subsequent complications. A small selection of unusual foreign bodies from the community will be presented. Finally, a selection of medical conditions which produce symptoms due to acquired intraluminal objects will be reviewed.

Prediction of locally advanced rectal cancer response to neoadjuvant chemoradiation therapy using volumetric multiparametric MRI-based radiomics.

PURPOSE: To assess the role of pretreatment multiparametric (mp)MRI-based radiomic features in predicting pathologic complete response (pCR) of locally advanced rectal cancer (LARC) to neoadjuvant chemoradiation therapy (nCRT). METHODS: This was a retrospective dual-center study including 98 patients (M/F 77/21, mean age 60 years) with LARC who underwent pretreatment mpMRI followed by nCRT and total mesorectal excision or watch and wait. Fifty-eight patients from institution 1 constituted the training set and 40 from institution 2 the validation set. Manual segmentation using volumes of interest was performed on T1WI pre-/post-contrast, T2WI and diffusion-weighted imaging (DWI) sequences. Demographic information and serum carcinoembryonic antigen (CEA) levels were collected. Shape, 1st and 2nd order radiomic features were extracted and entered in models based on principal component analysis used to predict pCR. The best model was obtained using a k-fold cross-validation method on the training set, and AUC, sensitivity and specificity for prediction of pCR were calculated on the validation set. RESULTS: Stage distribution was T3 (n = 79) or T4 (n = 19). Overall, 16 (16.3%) patients achieved pCR. Demographics, MRI TNM stage, and CEA were not predictive of pCR (p range 0.59-0.96), while several radiomic models achieved high diagnostic performance for prediction of pCR (in the validation set), with AUCs ranging from 0.7 to 0.9, with the best model based on high b-value DWI demonstrating AUC of 0.9 [95% confidence intervals: 0.67, 1], sensitivity of 100% [100%, 100%], and specificity of 81% [66%, 96%]. CONCLUSION: Radiomic models obtained from pre-treatment MRI show good to excellent performance for the prediction of pCR in patients with LARC, superior to clinical parameters and CEA. A larger study is needed for confirmation of these results.

Diagnostic Accuracy of Unenhanced Computed Tomography for Evaluation of Acute Abdominal Pain in the Emergency Department.

Importance: Intravenous (IV) contrast medium is sometimes withheld due to risk of complication or lack of availability in patients undergoing computed tomography (CT) for abdominal pain. The risk from withholding contrast medium is understudied. Objective: To determine the diagnostic accuracy of unenhanced abdominopelvic CT using contemporaneous contrast-enhanced CT as the reference standard in emergency department (ED) patients with acute abdominal pain. Design, Setting, and Participants: This was an institutional review board-approved, multicenter retrospective diagnostic accuracy study of 201 consecutive adult ED patients who underwent dual-energy contrast-enhanced CT for the evaluation of acute abdominal pain from April 1, 2017, through April 22, 2017. Three blinded radiologists interpreted these scans to establish the reference standard by majority rule. IV and oral contrast media were then digitally subtracted using dual-energy techniques. Six different blinded radiologists from 3 institutions (3 specialist faculty and 3 residents) interpreted the resulting unenhanced CT examinations. Participants included a consecutive sample of ED patients with abdominal pain who underwent dual-energy CT. Exposure: Contrast-enhanced and virtual unenhanced CT derived from dual-energy CT. Main outcome: Diagnostic accuracy of unenhanced CT for primary (ie, principal cause[s] of pain) and actionable secondary (ie, incidental findings requiring management) diagnoses. The Gwet interrater agreement coefficient was calculated. Results: There were 201 included patients (female, 108; male, 93) with a mean age of 50.1 (SD, 20.9) years and mean BMI of 25.5 (SD, 5.4). Overall accuracy of unenhanced CT was 70% (faculty, 68% to 74%; residents, 69% to 70%). Faculty had higher accuracy than residents for primary diagnoses (82% vs 76%; adjusted odds ratio [OR], 1.83; 95% CI, 1.26-2.67; P = .002) but lower accuracy for actionable secondary diagnoses (87% vs 90%; OR, 0.57; 95% CI, 0.35-0.93; P < .001). This was because faculty made fewer false-negative primary diagnoses (38% vs 62%; OR, 0.23; 95% CI, 0.13-0.41; P < .001) but more false-positive actionable secondary diagnoses (63% vs 37%; OR, 2.11, 95% CI, 1.26-3.54; P = .01). False-negative (19%) and false-positive (14%) results were common. Interrater agreement for overall accuracy was moderate (Gwet agreement coefficient, 0.58). Conclusion: Unenhanced CT was approximately 30% less accurate than contrast-enhanced CT for evaluating abdominal pain in the ED. This should be balanced with the risk of administering contrast material to patients with risk factors for kidney injury or hypersensitivity reaction.

Radiologic T staging of colon cancer: renewed interest for clinical practice.

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Delays in imaging diagnosis of acute abdominal pain in the emergency setting.

Acute abdominal pain is a common cause of ED visits and often requires imaging to identify a specific diagnosis. Prompt and appropriate imaging plays a crucial role in patient management and leads to improved patient outcomes, decreased hospital stay, and improved ED workflow. There are many cases of abdominal pain in the ED with delayed diagnosis and management secondary to a combination of institutional policies and knowledge deficits in current imaging guidelines. Inappropriate use of abdominal radiographs, use of oral contrast for CT abdomen and pelvis, and concern for iodinated contrast-induced acute kidney injury are three of the more commonly encountered roadblocks to prompt imaging diagnosis of abdominal pain. The purpose of this review is to discuss why these potential causes of delayed diagnosis occur and how radiologists can help improve both imaging and ED workflow by utilizing the most up-to-date imaging guidelines such the American College of Radiology (ACR) Appropriateness Criteria and ACR Manual on Contrast Media to assist clinicians working in the emergency setting.