American College of Radiology initiatives on prostate magnetic resonance imaging quality.

Magnetic resonance imaging (MRI) has become integral to diagnosing and managing patients with suspected or confirmed prostate cancer. However, the benefits of utilizing MRI can be hindered by quality issues during imaging acquisition, interpretation, and reporting. As the utilization of prostate MRI continues to increase in clinical practice, the variability in MRI quality and how it can negatively impact patient care have become apparent. The American College of Radiology (ACR) has recognized this challenge and developed several initiatives to address the issue of inconsistent MRI quality and ensure that imaging centers deliver high-quality patient care. These initiatives include the Prostate Imaging Reporting and Data System (PI-RADS), developed in collaboration with an international panel of experts and members of the European Society of Urogenital Radiology (ESUR), the Prostate MR Image Quality Improvement Collaborative, which is part of the ACR Learning Network, the ACR Prostate Cancer MRI Center Designation, and the ACR Appropriateness Criteria. In this article, we will discuss the importance of these initiatives in establishing quality assurance and quality control programs for prostate MRI and how they can improve patient outcomes.

LI-RADS: Looking Back, Looking Forward.

Since its initial release in 2011, the Liver Imaging Reporting and Data System (LI-RADS) has evolved and expanded in scope. It started as a single algorithm for hepatocellular carcinoma (HCC) diagnosis with CT or MRI with extracellular contrast agents and has grown into a multialgorithm network covering all major liver imaging modalities and contexts of use. Furthermore, it has developed its own lexicon, report templates, and supplementary materials. This article highlights the major achievements of LI-RADS in the past 11 years, including adoption in clinical care and research across the globe, and complete unification of HCC diagnostic systems in the United States. Additionally, the authors discuss current gaps in knowledge, which include challenges in surveillance, diagnostic population definition, perceived complexity, limited sensitivity of LR-5 (definite HCC) category, management implications of indeterminate observations, challenges in reporting, and treatment response assessment following radiation-based therapies and systemic treatments. Finally, the authors discuss future directions, which will focus on mitigating the current challenges and incorporating advanced technologies. Tha authors envision that LI-RADS will ultimately transform into a probability-based system for diagnosis and prognostication of liver cancers that will integrate patient characteristics and quantitative imaging features, while accounting for imaging modality and contrast agent.

An update on ductal plate malformations and fibropolycystic diseases of the liver.

A variety of cystic and fibrocystic lesions can occur in the liver, which may be single or multiple and etiologically can be acquired or have genetic underpinnings. Although the morphology of ductal plate development and various associated malformations has been well described, the genetic etiologies of many of these disorders are still poorly understood. Multiple clinical phenotypes in the liver are proposed to originate from ductal plate malformations: congenital hepatic fibrosis, Caroli's disease, Von Meyenburg complex, and the liver cysts of autosomal dominant polycystic kidney and liver diseases. Although many of the patients with these disorders, particularly with isolated liver involvement remain asymptomatic, some develop portal hypertension or symptoms from cyst enlargement. Development of hepatocellular malignancy is a risk in a small subset. Recent advances have made it now possible for some of these phenotypes to be genetically defined, and intriguingly animal models of adult polycystic liver disease suggest that abnormal organ development is not required. This review describes the current understanding, genetic underpinning, and key clinicopathologic and imaging features of these fibropolycystic liver diseases.

Clinical utility of MR/ultrasound fusion-guided biopsy in patients with lower suspicion lesions on active surveillance for low-risk prostate cancer.

BACKGROUND: The utility of Multiparametric magnetic resonance imaging (mpMRI) guided prostate biopsy among patients with prostate cancer (CaP) managed with active surveillance (AS) with low-suspicion lesions remains unsettled. METHODS: We performed a retrospective analysis of 415 men with low-risk CaP managed with active surveillance. We selected men with mpMRI visible index lesions scored as 2 or 3 according to Prostate Imaging Reporting and Data System (PI-RADS) version 2. The primary outcome was detection of clinically significant prostate cancer (csCaP) was defined as Gleason grade group ≥ 2. We assessed the diagnostic accuracy of biopsy approaches using area under the receiver operator characteristic (ROC) curve and evaluated factors associated with csCaP in these patients using multivariate logistic regression. RESULTS: CsCaP was identified in 22 of 125 patients (17.6%) with PI-RADS 2 or 3 index lesions during surveillance prostate biopsies. These included 10 (45.5%) diagnosed by systematic biopsy alone, 9 (40.9%) by targeted alone, and 3 (13.6%) by both approaches. On multivariable analysis, the only significant variable predicting the detection of csCaP in men with low-risk imaging mpMRI characteristics was higher PSAD (OR per 0.1 unit=2.26, 95% CI 1.25-4.06, P = 0.007. A PSAD cutoff of 0.1, 0.12 and 0.15 resulted in a negative predictive value (NPV) of 90.9%, 87.1% and 86.2%, respectively. When stratified by PI-RADS score, a PSAD cutoff of 0.1, 0.12 and 0.15 resulted in NPV of 96.2%, 90.6% and 89.7% and 86.2%, 84.2% and 83.3% for detection of csCaP in PI-RADS 2 and 3 lesions, respectively. In patients with PIRDAS 2 lesions, using a PSAD of 0.1 would potentially allow 51% of patients to avoid biopsy with only a 3.8% chance of missing csCaP. CONCLUSION: In men with clinical low-risk prostate cancer on active surveillance with PI-RADS 2 and 3 lesions, there is an almost 18% risk of upgrade to csCaP. Integration of PSAD may be a useful adjunctive tool in identifying patients at highest risk for upgrade despite favorable imaging findings. In men with PIRADS 2 lesions with PSAD ≤0.12 biopsy can be avoided. For men with PIRADS 2 lesions with PSAD ≤0.15 informed decision making regarding the AS intensity should include that these patients have a low risk (>10%) of developing csCaP. In men with PIRADS 3 lesions with PSAD >0.1, shared decision making should include discussion of a >10% miss rate of csCaP.

Real-Time MRI-Guided Prostate Interventions.

Prostate cancer (PCa) is the second most common cause of cancer death in males. Targeting MRI-visible lesions has led to an overall increase in the detection of clinically significant PCa compared to the prior practice of random ultrasound-guided biopsy of the prostate. Additionally, advances in MRI-guided minimally invasive focal treatments are providing new options for patients with PCa. This review summarizes the currently utilized real-time MRI-guided interventions for PCa diagnosis and treatment.

ACR-RADS Programs Current State and Future Opportunities: Defining a Governance Structure to Enable Sustained Success.

In the spring of 2021, the ACR approved a proposal to improve the consistency, transparency, and administrative oversight of the ACR Reporting and Data Systems (RADS). A working group of experts and stakeholders was convened to draft this governance document. Major advances include (1) forming a RADS Steering Committee, (2) establishing minimum requirements and evidence standards for new and existing RADS, and (3) outlining a governance structure and communication strategy for RADS.

The Effect of Esophageal Temperature Probes on Postoperative Dysphagia Following Primary Anterior Cervical Discectomy and Fusion: A Randomized Prospective Study.

BACKGROUND: The anterior approach to the cervical spine is associated with postoperative dysphagia. It is difficult to predict which patients are most at risk for dysphagia. The objective of this study was to determine if placing an esophageal temperature probe preoperatively would affect the severity and length of postoperative dysphagia. We hypothesize that use of an esophageal temperature probe would result in worse postoperative dysphagia at all measured time points as measured by the Swallowing-Quality of Life (SQAL-QOL) survey after anterior cervical discectomy and fusion (ACDF). METHODS: A total of 44 patients were enrolled in a prospective, randomized controlled trial and randomized into groups: 1 with an esophageal temperature probe placed at the time of surgery and 2 without. A total of 39 patients filled out postoperative SWAL-QOL questionnaires at their preoperatives. Using the survey results, the data were analyzed between groups and subanalyzed based on number of operative levels and sex. RESULTS: SWAL-QOL scores for patients undergoing 2-level ACDF with an esophageal temperature probe were significantly better compared with those without a probe at 2 weeks and 6 months postoperatively. These results were not significant at other time points in in the overall analysis, but a trend toward improved dysphagia scores at each time point postoperatively was seen with the probe group. No differences were found between the 2 groups with respect to age at the time of surgery, sex, and preoperative SWAL-QOL score. CONCLUSIONS: Placement of an esophageal temperature probe at the time of surgery significantly improved postoperative dysphagia scores in patients undergoing 2-level ACDF at 2 weeks and 6 months postoperatively. LEVEL OF EVIDENCE: 2 CLINICAL RELEVANCE: Placement of a temperature probe is a safe and effective technique that is readily available and easily applicable to the practice of spine surgery and may improve postoperative dysphagia after ACDF.

Feasibility of diffusion weighting with a local inside-out nonlinear gradient coil for prostate MRI.

PURPOSE: Prostate cancer remains the second leading cancer killer of men, yet it is also a disease with a high rate of overtreatment. Diffusion-weighted imaging (DWI) has shown promise as a reliable, grade-sensitive imaging method, but it is limited by low image quality. Currently, DWI quality image is directly related to low gradient amplitudes, since weak gradients must be compensated with long echo times. METHODS: We propose a new type of MRI accessory, an "inside-out" and nonlinear gradient, whose sole purpose is to deliver diffusion encoding to a region of interest. Performance was simulated in OPERA and the resulting fields were used to simulate DWI with two-compartment and kurtosis models. Experiments with a nonlinear head gradient prove the accuracy of DWI and apparent diffusion coefficient (ADC) maps encoded with nonlinear gradients. RESULTS: Simulations validated thermal and mechanical safety while showing a 5- to 10-fold increase in gradient strength over prostate. With these strengths, lesion contrast to noise ratio in ADC maps approximately doubled for a range of anatomical positions. Proof-of-principle experiments show that spatially varying b-values can be corrected for accurate DWI and ADC. CONCLUSIONS: Dedicated nonlinear diffusion encoding hardware could improve prostate DWI.

International Multi-Site Initiative to Develop an MRI-Inclusive Nomogram for Side-Specific Prediction of Extraprostatic Extension of Prostate Cancer.

BACKGROUND: To develop an international, multi-site nomogram for side-specific prediction of extraprostatic extension (EPE) of prostate cancer based on clinical, biopsy, and magnetic resonance imaging- (MRI) derived data. METHODS: Ten institutions from the USA and Europe contributed clinical and side-specific biopsy and MRI variables of consecutive patients who underwent prostatectomy. A logistic regression model was used to develop a nomogram for predicting side-specific EPE on prostatectomy specimens. The performance of the statistical model was evaluated by bootstrap resampling and cross validation and compared with the performance of benchmark models that do not incorporate MRI findings. RESULTS: Data from 840 patients were analyzed; pathologic EPE was found in 320/840 (31.8%). The nomogram model included patient age, prostate-specific antigen density, side-specific biopsy data (i.e., Gleason grade group, percent positive cores, tumor extent), and side-specific MRI features (i.e., presence of a PI-RADSv2 4 or 5 lesion, level of suspicion for EPE, length of capsular contact). The area under the receiver operating characteristic curve of the new, MRI-inclusive model (0.828, 95% confidence limits: 0.805, 0.852) was significantly higher than that of any of the benchmark models (p < 0.001 for all). CONCLUSIONS: In an international, multi-site study, we developed an MRI-inclusive nomogram for the side-specific prediction of EPE of prostate cancer that demonstrated significantly greater accuracy than clinical benchmark models.

Doubling of Decipher Biopsy Genomic Score Is Related to Disease Reclassification on Subsequent Surveillance Biopsy but Not Adverse Features on Radical Prostatectomy.

The utility of serial Decipher biopsy scores in a true active surveillance population is still unknown. In a man on active surveillance for low-risk prostate cancer, a doubling of the Decipher biopsy score within genomic low-risk category from first to the second biopsy related to biopsy reclassification to Gleason grade group 4 on the third biopsy. However, the final pathology at radical prostatectomy showed Gleason grade group 2 with an organ-confined disease. This case suggests that the genomic risk category of Decipher biopsy scores during active surveillance may be more informative than either the interval genomic score change or the biopsy Gleason grade group.

The Prognostic Association of Prostate MRI PI-RADS™ v2 Assessment Category and Risk of Biochemical Recurrence after Definitive Local Therapy for Prostate Cancer: A Systematic Review and Meta-Analysis.

PURPOSE: Although the Prostate Imaging-Reporting and Data System™ version 2 (PI-RADS™ v2) is a reliable diagnostic tool for significant prostate cancer, less is known about the prognostic significance of the structured reporting scheme for estimating oncologic outcomes after treatment. We aimed to synthesize the available evidence regarding the association of PI-RADS v2 score and risk of biochemical recurrence (BCR) among patients undergoing primary definitive treatment for prostate cancer. MATERIALS AND METHODS: We systematically queried the PubMed® and Web of Science™ databases to identify studies addressing the association between the PI-RADS v2 and treatment outcomes. We included studies through November 2020 that assessed the independent prognostic significance of PI-RADS v2. After assessing risk of bias and quality, we conducted a formal meta-analysis to estimate the pooled effects of prostate magnetic resonance imaging (MRI) classification on the risk of BCR. RESULTS: We identified 9 and 7 eligible studies including 2,274 and 1,215 patients for the systematic review and meta-analysis, respectively. Eight were conducted in the context of radical prostatectomy and 1 post-radiation. Among patients treated with radical prostatectomy, higher PI-RADS v2 scores were significantly associated with risk of BCR (pooled HR 3.06, 95% CI 2.16-4.33; p <0.01). There was no significant heterogeneity among studies. For all studies, PI-RADS v2 score remained significantly associated with BCR (pooled HR 3.19, 95% CI 2.28-4.45; p <0.01). CONCLUSIONS: Prostate MRI findings assessed with the PI-RADS v2 classification were independently associated with risk of BCR after definitive local therapy, primarily based on data from radical prostatectomy. These findings support the prognostic significance of MRI, in addition to its role in prostate cancer diagnosis.

Outcomes following outpatient anterior cervical discectomy and fusion for the treatment of myelopathy.

INTRODUCTION: Anterior cervical discectomy and fusion (ACDF) is a commonly performed procedure for the treatment of degenerative cervical disease. With continued increase in U.S. healthcare expenditure, surgeons have begun to more closely examine the benefits of performing ACDF in an outpatient setting to increase efficiency, reduce the overall financial burden on patients/providers, and provide streamlined care for these patients. The purpose of this study was to analyze outcomes following outpatient ACDF for the treatment of myelopathy. METHODS: 14,490 patients who had undergone ACDF for myelopathy from 2010 to 2018 were included in this retrospective study, of which 2956 (20.40%) patients were considered to have undergone outpatient surgery. Pearson chi-squared tests and Fischer's Exact Tests were used to analyze differences in categorical variables of demographics, preoperative comorbidities, and postoperative complications, while Mann-Whitney-U-Tests were used to compare mean values of continuous variables. Coarsened-exact-matching (CEM) was implemented to control for baseline differences in demographics and comorbidities, and post-matching diagnostics included multivariate and univariate imbalance measure assessment. Outcomes were compared between the CEM-matched inpatient and outpatients ACDF cohorts. RESULTS: Upon CEM-matching (L1-statistic <0.001), the outpatient cohort (n = 2610, 25.13%) demonstrated significantly lower rates of any complication (p < 0.001), minor complications (p = 0.001), urinary tract infections (p = 0.029), blood transfusions (p < 0.001), major complications (p < 0.001), deep incisional surgical site infections (p = 0.017), ventilator dependence (p = 0.027), cardiac arrest (p = 0.028), unplanned reoperations (p = 0.001), and mortality (p = 0.006) in the 30-day postoperative period when compared to inpatient controls (n = 7774, 74.87%). CONCLUSION: ACDF has been a target amongst spinal procedures as a prime candidate for outpatient surgery. However, no previous reports have described complication rates and perioperative parameters in the sub-population of outpatient ACDF patients with myelopathy. In addition to shorter times from admission to operating room, operative time, and LOS, our study also demonstrated lower rates of major and overall complications in outpatient ACDF's for myelopathy in comparison to their inpatient counterparts. Performing ACDF's for myelopathy in an outpatient setting may help to curb costs, improve outcomes, and serve as a valuable learning resource for graduate medical education with rapid turnovers and shorter operative times.

Use of Intravenous Gadolinium-Based Contrast Media in Patients With Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation.

Inaugural consensus statements were developed and endorsed by the American College of Radiology (ACR) and National Kidney Foundation to improve and standardize the care of patients with kidney disease who have indication(s) to receive ACR-designated group II or group III intravenous gadolinium-based contrast media (GBCM). The risk of nephrogenic systemic fibrosis (NSF) from group II GBCM in patients with advanced kidney disease is thought to be very low (zero events following 4931 administrations to patients with estimated glomerular filtration rate [eGFR] <30 mL/min per 1.73 m2; upper bounds of the 95% confidence intervals: 0.07% overall, 0.2% for stage 5D chronic kidney disease [CKD], 0.5% for stage 5 CKD and no dialysis). No unconfounded cases of NSF have been reported for the only available group III GBCM (gadoxetate disodium). Depending on the clinical indication, the potential harms of delaying or withholding group II or group III GBCM for an MRI in a patient with acute kidney injury or eGFR less than 30 mL/min per 1.73 m2 should be balanced against and may outweigh the risk of NSF. Dialysis initiation or alteration is likely unnecessary based on group II or group III GBCM administration.

Prostate Magnetic Resonance Imaging for Local Recurrence Reporting (PI-RR): International Consensus -based Guidelines on Multiparametric Magnetic Resonance Imaging for Prostate Cancer Recurrence after Radiation Therapy and Radical Prostatectomy.

BACKGROUND: Imaging techniques are used to identify local recurrence of prostate cancer (PCa) for salvage therapy and to exclude metastases that should be addressed with systemic therapy. For magnetic resonance imaging (MRI), a reduction in the variability of acquisition, interpretation, and reporting is required to detect local PCa recurrence in men with biochemical relapse after local treatment with curative intent. OBJECTIVE: To propose a standardised method for image acquisition and assessment of PCa local recurrence using MRI after radiation therapy (RP) and radical prostatectomy (RT). EVIDENCE ACQUISITION: Prostate Imaging for Recurrence Reporting (PI-RR) was formulated using the existing literature. An international panel of experts conducted a nonsystematic review of the literature. The PI-RR system was created via consensus through a combination of face-to-face and online discussions. EVIDENCE SYNTHESIS: Similar to with PI-RADS, based on the best available evidence and expert opinion, the minimum acceptable MRI parameters for detection of recurrence after radiation therapy and radical prostatectomy are set. Also, a simplified and standardised terminology and content of the reports that use five assessment categories to summarise the suspicion of local recurrence (PI-RR) are designed. PI-RR scores of 1 and 2 are assigned to lesions with a very low and low likelihood of recurrence, respectively. PI-RR 3 is assigned if the presence of recurrence is uncertain. PI-RR 4 and 5 are assigned for a high and very high likelihood of recurrence, respectively. PI-RR is intended to be used in routine clinical practice and to facilitate data collection and outcome monitoring for research. CONCLUSIONS: This paper provides a structured reporting system (PI-RR) for MRI evaluation of local recurrence of PCa after RT and RP. PATIENT SUMMARY: A new method called PI-RR was developed to promote standardisation and reduce variations in the acquisition, interpretation, and reporting of magnetic resonance imaging for evaluating local recurrence of prostate cancer and guiding therapy.

Deep learning-assisted differentiation of pathologically proven atypical and typical hepatocellular carcinoma (HCC) versus non-HCC on contrast-enhanced MRI of the liver.

OBJECTIVES: To train a deep learning model to differentiate between pathologically proven hepatocellular carcinoma (HCC) and non-HCC lesions including lesions with atypical imaging features on MRI. METHODS: This IRB-approved retrospective study included 118 patients with 150 lesions (93 (62%) HCC and 57 (38%) non-HCC) pathologically confirmed through biopsies (n = 72), resections (n = 29), liver transplants (n = 46), and autopsies (n = 3). Forty-seven percent of HCC lesions showed atypical imaging features (not meeting Liver Imaging Reporting and Data System [LI-RADS] criteria for definitive HCC/LR5). A 3D convolutional neural network (CNN) was trained on 140 lesions and tested for its ability to classify the 10 remaining lesions (5 HCC/5 non-HCC). Performance of the model was averaged over 150 runs with random sub-sampling to provide class-balanced test sets. A lesion grading system was developed to demonstrate the similarity between atypical HCC and non-HCC lesions prone to misclassification by the CNN. RESULTS: The CNN demonstrated an overall accuracy of 87.3%. Sensitivities/specificities for HCC and non-HCC lesions were 92.7%/82.0% and 82.0%/92.7%, respectively. The area under the receiver operating curve was 0.912. CNN's performance was correlated with the lesion grading system, becoming less accurate the more atypical imaging features the lesions showed. CONCLUSION: This study provides proof-of-concept for CNN-based classification of both typical- and atypical-appearing HCC lesions on multi-phasic MRI, utilizing pathologically confirmed lesions as "ground truth." KEY POINTS: • A CNN trained on atypical appearing pathologically proven HCC lesions not meeting LI-RADS criteria for definitive HCC (LR5) can correctly differentiate HCC lesions from other liver malignancies, potentially expanding the role of image-based diagnosis in primary liver cancer with atypical features. • The trained CNN demonstrated an overall accuracy of 87.3% and a computational time of < 3 ms which paves the way for clinical application as a decision support instrument.

Vertebral Artery Injury in the Cervical Spine: Anatomy, Diagnosis, and Management.

¼: Although rare, injury to the vertebral artery (VA) can occur after blunt trauma or iatrogenically during surgery. Clinicians should be aware of the anatomic variants of the VA, the presence of which may increase the risk of iatrogenic VA injury (VAI). ¼: If VAI is suspected following blunt trauma, rapid identification via advanced imaging modalities, such as computed tomography angiography, can help clarify the site of injury and guide management. ¼: VAI can be classified according to the Denver grading scale for blunt cerebrovascular injury, ranging from grade I to grade V, which includes intimal narrowing, pseudoaneurysm formation, complete occlusion, and arterial transection. ¼: Treatment modalities remain controversial and include anticoagulation, endovascular interventions, surgical tamponade, ligation, and microvascular repair. The choice of treatment is influenced by the setting of the injury (iatrogenic injury in the operating room versus blunt trauma in the field) and the laterality of the dominant VA with respect to brain perfusion.

¼ Although rare, injury to the vertebral artery (VA) can occur after blunt trauma or iatrogenically during surgery. Clinicians should be aware of the anatomic variants of the VA, the presence of which may increase the risk of iatrogenic VA injury (VAI).¼ If VAI is suspected following blunt trauma, rapid identification via advanced imaging modalities, such as computed tomography angiography, can help clarify the site of injury and guide management.¼ VAI can be classified according to the Denver grading scale for blunt cerebrovascular injury, ranging from grade I to grade V, which includes intimal narrowing, pseudoaneurysm formation, complete occlusion, and arterial transection.¼ Treatment modalities remain controversial and include anticoagulation, endovascular interventions, surgical tamponade, ligation, and microvascular repair. The choice of treatment is influenced by the setting of the injury (iatrogenic injury in the operating room versus blunt trauma in the field) and the laterality of the dominant VA with respect to brain perfusion.

PI-RADS Committee Position on MRI Without Contrast Medium in Biopsy-Naive Men With Suspected Prostate Cancer: Narrative Review.

The steadily increasing demand for diagnostic prostate MRI has led to concerns regarding the lack of access to and the availability of qualified MRI scanners and sufficiently experienced radiologists, radiographers, and technologists to meet the demand. Solutions must enhance operational benefits without compromising diagnostic performance, quality, and delivery of service. Solutions should also mitigate risks such as decreased reader confidence and referrer engagement. One approach may be the implementation of MRI without the use gadolinium-based contrast medium (bipara-metric MRI), but only if certain prerequisites such as high-quality imaging, expert interpretation quality, and availability of patient recall or on-table monitoring are mandated. Alternatively, or in combination, a clinical risk-based approach could be used for protocol selection, specifically, which biopsy-naive men need MRI with contrast medium (multiparametric MRI). There is a need for prospective studies in which biopsy decisions are made according to MRI without contrast enhancement. Such studies must define clinical and operational benefits and identify which patient groups can be scanned successfully without contrast enhancement. These higher-quality data are needed before the Prostate Imaging Reporting and Data System (PI-RADS) Committee can make evidence-based recommendations about MRI without contrast enhancement as an initial diagnostic approach for prostate cancer workup.

Use of Intravenous Iodinated Contrast Media in Patients With Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation.

Intravenous iodinated contrast media are commonly used with CT to evaluate disease and to determine treatment response. The risk of acute kidney injury (AKI) developing in patients with reduced kidney function following exposure to intravenous iodinated contrast media has been overstated. This is due primarily to historic lack of control groups sufficient to separate contrast-induced AKI (CI-AKI; ie, AKI caused by contrast media administration) from contrast-associated AKI (CA-AKI; ie, AKI coincident to contrast media administration). Although the true risk of CI-AKI remains uncertain for patients with severe kidney disease, prophylaxis with intravenous normal saline is indicated for patients who have AKI or an estimated glomerular filtration rate less than 30 mL/min/1.73 m2 who are not undergoing maintenance dialysis. In individual high-risk circumstances, prophylaxis may be considered in patients with an estimated glomerular filtration rate of 30-44 mL/min/1.73 m2 at the discretion of the ordering clinician.