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

Postoperative management in patients with complex aortic aneurysms

Patients with complex aortic aneurysms (CAA) are often high risk due to advanced age and widespread atherosclerosis affecting numerous vascular territories. Therefore, a thorough perioperative evaluation is needed prior to performing in any type of aortic repair, regardless of whether an endovascular or open surgical approach is selected. Because these operations are technically demanding and often result in end organ ischemia, it is not surprising that complex aortic repair carries significant risk of morbidity and mortality. Disabling complications such as dialysis, major stroke and paraplegia constitute the main limitation of complex aortic repair. The aim of this article was to review postoperative management to mitigate complications after CAA repair.

A multi-disciplinary, comprehensive approach to management of children with heterotaxy

Heterotaxy (HTX) is a rare condition of abnormal thoraco-abdominal organ arrangement across the left-right axis of the body. The pathogenesis of HTX includes a derangement of the complex signaling at the left-right organizer early in embryogenesis involving motile and non-motile cilia. It can be inherited as a single-gene disorder, a phenotypic feature of a known genetic syndrome or without any clear genetic etiology. Most patients with HTX have complex cardiovascular malformations requiring surgical intervention. Surgical risks are relatively high due to several serious comorbidities often seen in patients with HTX. Asplenia or functional hyposplenism significantly increase the risk for sepsis and therefore require antimicrobial prophylaxis and immediate medical attention with fever. Intestinal rotation abnormalities are common among patients with HTX, although volvulus is rare and surgical correction carries substantial risk. While routine screening for intestinal malrotation is not recommended, providers and families should promptly address symptoms concerning for volvulus and biliary atresia, another serious morbidity more common among patients with HTX. Many patients with HTX have chronic lung disease and should be screened for primary ciliary dyskinesia, a condition of respiratory cilia impairment leading to bronchiectasis. Mental health and neurodevelopmental conditions need to be carefully considered among this population of patients living with a substantial medical burden. Optimal care of children with HTX requires a cohesive team of primary care providers and experienced subspecialists collaborating to provide compassionate, standardized and evidence-based care. In this statement, subspecialty experts experienced in HTX care and research collaborated to provide expert- and evidence-based suggestions addressing the numerous medical issues affecting children living with HTX.

Contrast-associated acute kidney injury in acute ischemic stroke patients following multi-dose iodinated contrast

BACKGROUND AND OBJECTIVE

lthough intravenous contrast in neuroimaging has become increasingly important in selecting patients for stroke treatment, clinical concerns remain regarding contrast-associated acute kidney injury (CA-AKI). Given the increasing utilization of CT angiography and/or perfusion coupled with cerebral angiography, the purpose of this study was to assess the association of CA-AKI and multi-dose iodinated contrast in acute ischemic stroke (AIS) patients.

MATERIALS AND METHODS

etrospective review of AIS patients at a comprehensive stroke center was performed from January 2018 to December 2019. Data collection included patient demographics, stroke risk factors, stroke severity, discharge disposition, modified Rankin Scale, contrast type/volume, and creatinine levels (baseline, 48-72 h). CA-AKI was defined as creatinine increase ≥ 25 % from baseline. Bivariate analyses and multivariable logistic regression models were implemented to compare AIS patients with multi-dose and single-dose contrast.

RESULTS

Of 440 AIS patients, 215 (48.9 %) were exposed to a single-dose contrast, and 225 (51.1 %) received multi-dose. In single-dose patients, CA-AKI at 48/72 h was 9.7 %/10.2 % compared to 8.0 %/8.9 % in multi-dose patients. Multi-dose patients were significantly more likely to receive a higher volume of contrast (mean 142.1 mL versus 80.8 mL; p < 0.001), but there was no significant difference in their creatinine levels or CA-AKI. NIHSS score (OR=1.08, 95 % CI=[1.04,1.13]), and patient transfer from another hospital (OR=3.84, 95 % CI=[1.94,7.62]) were significantly associated with multi-dose contrast.

CONCLUSIONS

No significant association between multi-dose iodinated contrast and CA-AKI was seen in AIS patients. Concerns of CA-AKI should not deter physicians from pursuing timely and appropriate contrast-enhanced neuroimaging that may optimize treatment outcomes in AIS patients.

Endovascular Repair of Complex Aortic Aneurysms

Fenestrated-branched endovascular aortic repair (FB-EVAR) has gained widespread acceptance in patients with complex aortic aneurysms. It has evolved from an alternative to treat elderly and higher risk patients to the first line of treatment in most patients with suitable anatomy, independent of the clinical risk. Currently, these devices are available off-the-shelf (ready to use) and tailored to the patient anatomy with the options of fenestrated, branched and mixed fenestrated, and branched designs. Reports from single and multicenter experiences and systematic reviews have shown lower mortality and morbidity for FB-EVAR compared with historical results of open surgical repair. The main advantages are noted on mortality, respiratory complications, acute kidney injury, and length of hospital stay. The purpose of this article is to review the advances in the endovascular repair of complex aortic aneurysms exploring the indications for treatment, preoperative evaluation, patient selection, device design, and implantation technique.

Optimizing low contrast volume thoracic CT angiography: From the basics to the advanced

Contrast-enhanced CT angiography (CTA) is a widely used, noninvasive imaging technique for evaluating cardiovascular structures. Contrast-induced nephrotoxicity is a concern in renal disease; however, the true nephrotoxic potential of iodinated contrast media (CM) is unknown. If a renal impaired patient requires CTA, it is important to protect the kidneys from further harm by reducing total iodinated CM volume while still obtaining diagnostic quality imaging. These same reduced volume CM techniques can also be applied to nonrenal impaired patients in times of CM shortage. This educational review discusses several modifications to CTA that can be adapted to both conventional 64-slice and the newer generation CT scanners which enable subsecond acquisition with a reduced CM volume technique. Such modifications include hardware and software adjustments and changes to both the volume and flow rate of administered CM, with the goal to reduce the dose of CM without compromising diagnostic yield.

The Incidence and Associated Risk Factors of Contrast-Induced Nephropathy after Contrast-Enhanced Computed Tomography in the Emergency Setting: A Systematic Review

Iodinated contrast media (ICM) during contrast-enhanced computed tomography (CECT) in the emergency department (ED) is essential to diagnose acute conditions, despite risks of contrast-induced nephropathy (CIN) development and its associated complications. This systematic review aims to evaluate the incidence of CIN and CIN-induced complications, and to explore the relevance of classical risk factors for CIN among ED patients receiving ICM. PubMed, Cochrane, and Web of Science were used on 30 August 2021 to search for peer-reviewed English articles reporting on CIN incidence among ED patients aged ≥18 years who underwent an intravenous CECT. The inclusion criteria included studies that were in English, peer-reviewed, and involved ED patients aged ≥18 years who underwent single intravenous CECT. Studies on intra-arterial procedures and preventive strategies, meta-analyses, clinical guidelines, review articles, and case reports were excluded. The JBI critical appraisal checklist was applied to assess the risk of bias. In total, 18 studies were included wherein 15 were retrospective studies while three were prospective studies. We found a relatively higher CIN incidence in the ED, with variations owing to the CIN definitions. Several classical risk factors including acute hypotension remain linked to CIN onset in ED settings unlike factors such as age and diabetes. While risk of adverse renal events due to CIN is low, there is higher risk of CIN-induced mortality in the ED. Therefore, with the higher incidence of CIN and CIN-induced mortality rates in the ED, ICM administration during CECT in the ED should still be clinically justified after assessing both benefits and risks.

Acute Colonic Pseudo-Obstruction

Acute colonic pseudo-obstruction (ACPO) is a functional disorder of the large intestine distinguished by colonic dysmotility resulting in colonic distension in the absence of mechanical obstruction. The underlying pathophysiology of ACPO remains unclear despite technological advances in understanding the physiology of colonic motility, such as spatio-temporal mapping and high-resolution manometry. In many ways, the management of ACPO has remained relatively unchanged for 40 years. Patients with perforation or suspected ischemia undergo operative intervention, while patients without undergo initial conservative management with bowel rest, correction of electrolyte disturbances, and mobilization. Patients who fail conservative management or have prominent cecal dilatation undergo decompression with either neostigmine or colonoscopy. A subset of patients with ACPO will have recurrent symptoms despite endoscopic and medical management. For these patients who are difficult to manage, an underlying colonic functional disorder, such as slow-transit dysmotility or chronic intestinal pseudo-obstruction may be considered. The following review of ACPO aims to provide a concise update of the causes, diagnosis, and management of this emergency surgical condition.

The Incidence of Contrast-Induced Nephropathy and the Need of Dialysis in Patients Receiving Angiography: A Systematic Review and Meta-Analysis

Objectives

The risk of dialysis following contrast exposure is unclear. We aimed to examine the overall risk of contrast induced nephropathy and the need of dialysis based on a systematic review with random-effects meta-analysis.

Methods

We searched the electronic database including PubMed, Medline, Embase, and Cochrane Library from inception to 31 October, 2020 with predetermined search term to identify relevant studies. Observational studies investigating the association between contrast induced nephropathy after angiography and the need of dialysis were included, and summary risks were estimated. Two independent reviewers extracted the data, followed with random effects model to calculate the overall pooled incidence of contrast induced nephropathy and the need of dialysis after angiography. Subgroup-analysis and meta-regression were performed to assess heterogeneity of incidence across studies.

Results

Of 2,243 identified articles, 259 met our inclusion criteria were included in the meta-analysis after screening. Pooled effect estimates had the following summary incidence proportion for contrast induced nephropathy after angiography: 9.06% (95% CI: 8.53–9.58%; derived from 120 studies) and 0.52% (95% CI: 0.37–0.70%; derived from 110 studies) for the need of dialysis, respectively. The stratified summary incidence proportion of contrast induced nephropathy after contrast administration via intra-arterial route was 9.60% (95% CI: 9.0–10.2%; derived from 106 studies) and was 0.6% (95% CI: 0.40–0.80%; derived from 100 studies) for the need of dialysis, respectively. Our meta-regressions found that the amount of contrast medium exposure was associated with contrast-induced nephropathy.

Conclusion

The potential risk of dialysis needs to be communicated to patients undergoing procedures requiring contrast, especially via intra-arterial exposure.

Systematic Review Registration

[https://reurl.cc/8Wrlry], identifier [CRD42020170702].

A systematic review of the incidence of hypersensitivity reactions and post-contrast acute kidney injury after ioversol: part 2-intra-arterial administration

Objectives

To evaluate the incidence of adverse drug reactions (ADRs), including hypersensitivity reactions (HSRs) and post-contrast acute kidney injury (PC-AKI), after intra-arterial (IA) administration of ioversol.

Methods and materials

A systematic literature search was performed (1980–2021) and studies documenting IA use of ioversol, and reporting safety outcomes were selected. Key information on study design, patients’ characteristics, indication, dose, and type of safety outcome were extracted.

Results

Twenty-eight studies (including two pediatric studies) with 8373 patients exposed to IA ioversol were selected. Studies were highly heterogenous in terms of design, PC-AKI definition, and studied population. PC-AKI incidence after coronary angiography was 7.5–21.9% in a general population, 4.0-26.4% in diabetic patients, and 5.5–28.9% in patients with chronic kidney disease (CKD). PC-AKI requiring dialysis was rare and reported mainly in patients with severe CKD. No significant differences in PC-AKI rates were shown in studies comparing different iodinated contrast media (ICM). Based on seven studies of ioversol clinical development, the overall ADR incidence was 1.6%, comparable to that reported with other non-ionic ICM. Pediatric data were scarce with only one study reporting on PC-AKI incidence (12%), and one reporting on ADR incidence (0.09%), both after coronary angiography.

Conclusions

After ioversol IA administration, PC-AKI incidence was highly variable between studies, likely reflecting the heterogeneity of the included study populations, and appeared comparable to that reported with other ICM. The rate of other ADRs appears to be low. Well-designed studies are needed for a better comparison with other ICM.

Key Points

• PC-AKI incidence after IA administration of ioversol appears to be comparable to that of other ICM, despite the high variability between studies.

• The need for dialysis after IA administration of ioversol is rare.

• No obvious difference was found regarding the safety profile of ioversol between IA and IV administration.

Is a Patient with Paget's Disease of Bone Suitable for Living Kidney Donation?-Decision-Making in Lack of Clinical Evidence

Living donor kidney transplantation is a widely performed medical procedure. Living kidney donation requires an in-depth health assessment of candidates. The potential living kidney donor must remain healthy after kidney removal. A consequence of donation can be a decrease in glomerular filtration rate (GFR), and donors can become at risk of developing chronic kidney disease (CKD). We present a rationale for potential living kidney donor withdrawal due to Paget's disease of bone (PDB) based on a literature review. The treatment for PDB includes the use of, for example, non-steroidal anti-inflammatory drugs (NSAIDs), which can lead to acute kidney injury (AKI) as well as CKD, or bisphosphonates, which are not recommended for patients with decreased GFR.

Acute Kidney Injury Following Transcatheter Aortic Valve Implantation: Association with Contrast Media Dosage and Contrast Media Based Risk Predication Models

The effect of contrast media (CM), delivered prior to- and during transcatheter aortic valve implantation (TAVI), on kidney function, following the procedure, is debatable. Consequently, the performance of CM-based, acute kidney injury (AKI) risk prediction models is also questionable. We retrospectively studied 210 patients that underwent TAVI. We recorded the dose of CM used prior and during TAVI, calculated the results of different AKI risk assessment models containing a CM module, and tested their association with AKI after the procedure. AKI was diagnosed in 38 patients (18.1%). The baseline estimated glomerular filtration rate (eGFR) was lower in the AKI+ group compared to AKI− group (51 ± 19.3 versus 64.5 ± 19 mL/min/1.73 mr², respectively). While the dose of CM delivered prior to TAVI, during TAVI or the cumulative amount of both did not differ between the groups, the results of all tested risk models were higher in AKI+ patients. However, by multivariable analysis, only eGFR had a consistent independent association with AKI. We suggest that the dose of CM delivered prior or during TAVI is not associated with AKI and that the predictive power of CM based AKI risk models is, in all probability, limited to eGFR alone.

The Pathophysiology and the Management of Radiocontrast-Induced Nephropathy

Contrast-induced nephropathy (CIN) is an impairment of renal function that occurs after the administration of an iodinated contrast medium (CM). Kidney dysfunction in CIN is considered transient and reversible in most cases. However, it is the third most common cause of hospital-acquired acute kidney injury and is associated with increased morbidity and mortality, especially in high-risk patients. Diagnostic and interventional procedures that require intravascular CM are being used with increasing frequency, especially among the elderly, who can be particularly susceptible to CIN due to multiple comorbidities. Therefore, identifying the exact mechanisms of CIN and its associated risk factors is crucial not only to provide optimal preventive management for at-risk patients, but also to increase the feasibility of diagnostic and interventional procedure that use CM. CM induces kidney injury by impairing renal hemodynamics and increasing the generation of reactive oxygen species, in addition to direct cytotoxicity. Periprocedural hydration is the most widely accepted preventive strategy to date. Here, we review the latest research results on the pathophysiology and management of CIN.

A systematic review of the incidence of hypersensitivity reactions and post-contrast acute kidney injury after ioversol in more than 57,000 patients: part 1-intravenous administration

OBJECTIVES

To evaluate the incidence of adverse drug reactions (ADRs), including hypersensitivity reactions (HSRs) and post-contrast acute kidney injury (PC-AKI), after intravenous (IV) administration of ioversol.

MATERIALS AND METHODS

A systematic literature search (1980-2021) of studies documenting IV use of ioversol and presence or absence of ADRs, HSRs, or PC-AKI was performed. Key information including patients' characteristics, indication and dose of ioversol, safety outcome incidence, intensity and seriousness were extracted.

RESULTS

Thirty-one studies (> 57,000 patients) were selected, including 4 pediatric studies. The incidence of ADRs in adults was reported in 12 studies from ioversol clinical development with a median (range) of 1.65% (0-33.3%), and 3 other studies with an incidence between 0.13 and 0.28%. The incidence of HSRs (reported in 2 studies) ranged from 0.20 to 0.66%, and acute events (4 studies) from 0.23 to 1.80%. Severe reactions were rare with a median (range) of 0 (0-4%), and none were reported among pediatric patients. The incidence of ADRs and HSRs with ioversol, especially those of severe intensity, was among the lowest in studies comparing different iodinated contrast media (ICM) of the same class. PC-AKI incidence was variable (1-42% in 5 studies); however, ioversol exposure per se did not increase the incidence.

CONCLUSIONS

When administered by the IV route, ioversol has a good safety profile comparable to that of other ICM within the same class, with a low incidence of severe/serious ADRs overall, and particularly HSRs. PC-AKI incidence does not seem to be increased compared to patients who did not receive ioversol. Further well-designed studies are warranted to confirm these results.

KEY POINTS

• Ioversol has a good safety profile in adult and pediatric patients when IV administered. • ADR and HSR incidence with ioversol, especially those of severe intensity, was among the lowest compared to other ICM. • IV administration of ioversol per se did not increase PC-AKI incidence.

Cardiac Computed Tomography Versus Transesophageal Echocardiography for the Detection of Left Atrial Appendage Thrombus: A Systemic Review and Meta-Analysis

Background Transesophageal echocardiography (TEE) has been considered the gold standard for left atrial appendage (LAA) thrombus detection. Nevertheless, TEE may sometimes induce discomfort and cause complications. Cardiac computed tomography has been studied extensively for LAA thrombus detection. We performed this systemic review and meta-analysis to assess the diagnostic accuracy of cardiac computed tomography for LAA thrombus detection compared with TEE. Methods and Results A systemic search was conducted in the PubMed, Embase, and Cochrane Library databases from January 1977 to February 2021. Studies performed for assessment diagnostic accuracy of cardiac computed tomography on LAA thrombus compared with TEE were included. Summary sensitivity, specificity, and posterior probability of LAA thrombus was calculated by using bivariate random-effects model. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used for the quality assessment. A total of 27 studies involving 6960 patients were included in our study. The summary sensitivity of early imaging studies was 0.95 (95% CI, 0.79-0.99), and the specificity was 0.89 (95% CI, 0.85-0.92). The positive posterior probability was 19.11%, and the negative posterior probability was 0.16%. The summary sensitivity of delayed imaging studies was 0.98 (95% CI, 0.92-1.00), and the specificity was 1.00 (95% CI, 0.98-1.00). The positive posterior probability was 95.76%, and the negative posterior probability was 0.12%. The delayed imaging method significantly improved the specificity (1.00 versus 0.89; P<0.05) and positive posterior probability (95.76% versus 19.11%; P<0.05). Conclusions Cardiac computed tomography with a delayed imaging is a reliable alternative to TEE. It may save the patient and health care from an excess TEE. Registration URL: https://www.crd.york.ac.uk/PROSPERO; Unique identifier: CRD42021236352.

Multidisciplinary Management of Complicated Pancreatitis: What Every Interventional Radiologist Should Know

Management of acute pancreatitis is challenging in the presence of local complications that include pancreatic and peripancreatic collections and vascular complications. This review, targeted for interventional radiologists, describes minimally invasive endoscopic, image-guided percutaneous, and surgical procedures for management of complicated pancreatitis and provides insight into the procedures' algorithmic application. Local complications are optimally managed in a multidisciplinary team setting that includes advanced endoscopists; pancreatic surgeons; diagnostic and interventional radiologists; and specialists in infectious disease, nutrition, and critical care medicine. Large symptomatic or complicated sterile collections and secondary infected collections warrant drainage or débridement. The drainage is usually delayed for 4-6 weeks unless clinical deterioration warrants early intervention. If collections are accessible by endoscopy, endoscopic procedures are preferred to avoid pancreaticocutaneous fistulas. Image-guided percutaneous drainage is indicated for symptomatic collections that are not accessible for endoscopic drainage or that present in the acute setting before developing a mature wall. Peripancreatic arterial pseudoaneurysms should be embolized before necrosectomy procedures to prevent potentially life-threatening hemorrhage. Surgical procedures are reserved for symptomatic collections that persist despite endoscopic or interventional drainage attempts. Understanding these procedures facilitates their integration by interventional radiologists into the complex longitudinal care of patients with complicated pancreatitis.

Pulmonary embolism risk factors for intensive care unit anticoagulated COVID-19 patients undergoing computed tomography angiography

Objetivo

Avaliar a incidência de embolia pulmonar, seu relacionamento com os níveis de dímero D e outros possíveis fatores associados, além dos efeitos adversos da anticoagulação e meios de contraste.

Métodos

Conduziu-se um estudo de coorte retrospectiva em um hospital público chileno. Foram incluídos os pacientes com idade acima de 18 anos com COVID-19, mecanicamente ventilados na unidade de terapia intensiva, admitidos entre março e junho de 2020. Todos os pacientes receberam tromboprofilaxia com heparina, que foi aumentada até uma dose de anticoagulação com níveis de dímero D acima de 3µg/mL.

Resultados

Foram acompanhados 127 pacientes, dos quais 73 foram submetidos à angiografia por tomografia computadorizada (média de idade de 54 ± 12 anos; 49 homens). Sessenta e dois dos 73 pacientes (84,9%) receberam anticoagulação total antes da angiografia por tomografia computadorizada. Além disso, 18 dos 73 pacientes tiveram embolia pulmonar (24,7%). Na comparação entre pacientes com e sem embolia pulmonar, não se observaram diferenças significantes em termos de idade, sexo, obesidade, tabagismo, escores de Wells e Genebra revisado, dímero D ou mortalidade. O uso de anticoagulantes foi similar em ambos os grupos. O número de dias desde o início da anticoagulação até a angiografia por tomografia computadorizada foi significantemente menor no grupo com embolia pulmonar (p = 0,002). Três pacientes tiveram lesão renal aguda após o contraste (4,1%), e um paciente teve sangramento importante.

Conclusão

Apesar da anticoagulação, um em cada quatro pacientes com COVID-19 submetidos à ventilação mecânica e avaliados com angiografia por tomografia computadorizada apresentou embolia pulmonar. Com uma maior demora para realização da angiografia por tomografia computadorizada após início de anticoagulação empírica, identificou-se um número significantemente menor de embolias

Recurrent Renal Allograft Torsion After Simultaneous Kidney and Pancreas Transplantation: Is it Still Possible to Salvage the Graft? A Case Report

BACKGROUND

Kidney allograft torsion (KAT) is defined as a rotation of the renal allograft around its vascular pedicle. It is a rare complication with high rate of graft loss. The nonspecific presentation and inability to provide a definitive diagnosis by imaging, mainly in cases of partial torsion, often delay the diagnosis and treatment. We report a case of recurrent complete torsion of the renal allograft after simultaneous kidney and pancreas transplantation, requiring 2 emergency exploratory laparotomies.

CASE REPORT

A 38-year-old woman with a history of intraperitoneal simultaneous kidney and pancreas transplantation underwent 2 separate emergency exploratory laparotomies secondary to complete renal allograft torsion, respectively, 7 and 11 months after the transplant. In both episodes, no adhesions were encountered. During the first operation, nephropexy was performed. During the second operation, an abdominal wall mesh was placed and fixed to the abdominal wall. Acute kidney injury related to KAT recovered in both occasions with a creatinine of 1.3 mg/dL at 4 months follow-up.

CONCLUSIONS

Renal torsion always should be suspected in intraperitoneally placed kidneys presenting with nonspecific symptoms, abdominal pain, oliguria, and worsening kidney function. Surgical exploration should be considered to salvage the renal graft. This case illustrates the reversibility of a severe injury related to this vascular complication with an adequate return to baseline kidney function even when diagnosis and surgical treatment of KAT might be delayed secondary to its misleading clinical presentation.

Contrast-induced nephropathy in non-cardiac vascular procedures, a narrative review: Part 2

This is Part 2 of a narrative review summarizing the literature on CIN after non-cardiac vascular diagnostic or therapeutic procedures, focusing on peripheral artery disease (PAD) and renal artery stenosis (RAS). Part 1 discussed CIN in relation to aortic aneurysms and carotid stenosis. We comment on the incidence, biomarkers, risk factors, and consequences of CIN in patients with PAD or RAS, as well as on strategies to prevent CIN. Future perspectives in the field of CIN in relation to non-cardiac vascular procedures are also considered.

Challenges in the diagnostic approach of suspected pulmonary embolism in COVID-19 patients

Accumulating studies on COVID-19 patients report high incidences of thrombotic complications, but guidance on the best diagnostic approach for suspected pulmonary embolism (PE) in COVID-19 patients is lacking. Diagnosing PE in these patients is challenging as signs and symptoms of PE and COVID-19 show wide overlap, D-dimer levels are often elevated in the absence of thrombosis and computed tomography pulmonary angiography (CTPA) may be unfeasible in the case of severe renal impairment and/or hemodynamic instability.This narrative review discusses available literature and guidelines on current diagnostic algorithms for suspected PE in special patient populations, in particular COVID-19. A special focus is on reviewing the literature aimed at identifying symptoms with a high suspicion for PE and on the diagnostic performance of diagnostic algorithms for suspected PE in the setting of COVID-19.Based on available literature, the index of suspicion for PE should be high in the case of unexplained abrupt worsening of respiratory status, typical symptoms of deep-vein thrombosis and/or acute unexplained right ventricular dysfunction. Despite the lack of prospective diagnostic management studies, we propose to adhere to current diagnostic algorithms applying assessment of pretest probability and D-dimer testing as available evidence suggests that these might be considered safe. Preferably, algorithms using adjusted D-dimer thresholds are recommended as it likely improves the yield of the clinical decision rule/D-dimer combination.

Optimized Bolus Threshold for Dual-Energy CT Angiography with Monoenergetic Images: A Randomized Clinical Trial

Background The bolus-tracking technique from single-energy CT has been applied to dual-energy CT (DECT) without optimization or validation. Further optimization is imperative because of a paucity of literature and differences in the attenuation profile of virtual monoenergetic images (VMIs). Purpose To determine the optimal trigger threshold with bolus-tracking technique for DECT angiography (DECTA) in a phantom study and assess the feasibility of an optimized threshold for bolus-tracking technique in DECTA at 40 keV with a 50% reduced iodine dose in human participants. Materials and Methods A phantom study with rapid kilovoltage-switching DECT was performed to determine the optimal threshold for each kiloelectron-volt VMI. In a prospective study, consecutive participants who underwent whole-body CT angiography (CTA) from August 2018 to July 2019 were randomized into three groups: single-energy CTA (SECTA) with standard iodine dose (600 mg of iodine per kilogram), DECTA with 50% reduced iodine dose (300 mg of iodine per kilogram) by using a conventional threshold, and DECTA with 300 mg of iodine per kilogram by using an optimized threshold. A trigger threshold of 100 HU at 120 kVp was used as a reference for comparison. Injected iodine doses and aortic CT numbers were compared among the three groups using Kruskal-Wallis test. Results Ninety-six participants (mean age ± standard deviation, 72 years ± 9; 80 men) were evaluated (32 participants in each group). The optimized threshold for VMIs at 40 keV was 30 HU. The median iodine dose was lower in the optimized DECTA group (13 g) compared with conventional DECTA (19 g) and SECTA (26 g) groups (P < .017 for each comparison). The median aortic CT numbers were higher in the order corresponding to conventional DECTA (655-769 HU), optimized DECTA (543-610 HU), and SECTA (343-359 HU) groups (P < .001). Conclusion The optimized trigger threshold of 30 HU for bolus-tracking technique during dual-energy CT angiography at 40 keV achieved lower iodine load while maintaining aortic enhancement. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Malayeri in this issue.

Association between urine pH and risk of contrast-associated acute kidney injury among patients after emergency percutaneous coronary intervention: a V-shape relationship?

Aim

We investigated whether perioperative urine pH was associated with contrast-associated acute kidney injury (CA-AKI) in patients undergoing emergency percutaneous coronary intervention (PCI).

Methods

The study enrolled 1109 consecutive patients undergoing emergency PCI. Patients were divided into three groups based on perioperative urine pH (5.0–6.0, 6.5– 7.0, 7.5–8.5). The primary endpoint was the development of CA-AKI, defined as an absolute increase ≥ 0.3 mg/dL or a relative increase ≥ 50% from baseline serum creatinine within 48 h after contrast medium exposure.

Results

Overall, 181 patients (16.3%) developed contrast-associated acute kidney injury. The incidences of CA-AKI in patients with urine pH 5.0–6.0, 6.5–7.0, and 7.5–8.5 were 19.7%, 9.8%, and 23.3%, respectively. After adjustment for potential confounding factors, perioperative urine pH 5.0–6.0 and 7.5–8.5 remained independently associated with CA-AKI [odds ratio (OR)1.86, 95% confidence interval (CI) 1.25–2.82, P = 0.003; OR 2.70, 95% CI 1.5–4.68, P < 0.001, respectively]. The association was consistent in subgroups of patients stratified by several CA-AKI risk predictors. However, the risk of CA-AKI associated with urine pH 7.5–8.5 was stronger in patients with worse renal function (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m²) (HR 5.587, 95% CI 1.178–30.599 vs. HR 2.487, 95% CI 1.331–4.579; overall interaction P < 0.05).

Conclusion

The urine pH and CA-AKI may underlie the V-shape relationship.

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.

Morphological and radiological study of lymph nodes in dromedaries in Algeria

Despite significant progress in the study of the subtle mechanisms of interaction between cellular and molecular elements in immune responses, the general structure of the organs of the immune system, including the lymph node, has not been sufficiently studied, in particular in large farm animals. The lymph nodes of sexually mature camels have been studied anatomically and morphologically and advanced studies conducted using an X-ray system and a computer densitometer scanner with injection of a contrast medium. The topography and characteristics of the morphometric parameters (absolute and relative mass, linear measurements, volume) of certain somatic and visceral lymph nodes were determined. The mass of the lymph nodes studied varies according to the location and the interest of the organ in the satellite defense of the lymphoid system, For part of the x-ray examination of the lymph nodes, organs of large inguinal and axillary shape were selected after passing through a solution of tetraethyl-4,4-diamino-triphenylmethane oxalate, the lymph vessels were dilated and darkened, then iodine injections were made into the afferent lymphatic vessel of two lymph nodes; they were placed on the radiological cassette, a photograph taken on conventional radiography, for computer densitometer, the examination was made without preparation of the organs. A capsule encompasses the parenchyma of the lymph node, whose internal structure is composed of different zones, cortical, paracortical and medullary, on the one hand the lymphatic vessels were very clear especially with the conventional radiography with preparation of the organs, while the computer densitometer clearly revealed the deep texture of the parenchyma, basing it on the intensity of emission saturation from the use of computer densitometer.