Imaging Pearls ❯ Kidney ❯ Contrast
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- “The common misconception of the link between a history of shellfish allergies and increased risk of iodinated contrast allergy likely originated from studies in the early 1970s. For example, in 1973, Witten and colleagues reported that IV contrast allergic reactions were seen in 6% of patients with a prior history of seafood allergy.5 However, medical literature in the last 2 decades has debunked this myth, and demonstrated that no such relationship actually exits. Hypersensitivity reactions can be classified as immunoglobulin E (IgE)-mediated or non-IgE-mediated. IgE-mediated allergic reactions require an antigen, and iodine is a chemical element; therefore, it does not play such a role and cannot elicit an immune response. Allergic reactions to seafood are due to specific proteins, such as parvalbumins or tropomyosins. Reactions to IV contrast are most likely related to some other component of the contrast media and not the iodine itself. Ultimately, the strongest predictor of future contrast reactions is a history of prior contrast reaction, which confers a 5 fold higher risk.”
Potpourri of Contrast Controversies and Myths Where Is the Actual Evidence?
Miltiadis Tembelis, Gregg Blumberg,Luis Colon-Flores et al.
Radiol Clin N Am - (2024) (in press) - “As a consequence of this very commonly encountered misconception, many patients are affected by either undergoing suboptimal nonenhanced imaging examinations or receiving unnecessary premedication treatment protocols. This problem becomes more relevant in the context of the estimated 2.3% prevalence of seafood allergy in the United States, which translates to approximately 6.6 million Americans.8 With the goal of better serving this population and eradicating this myth, a more robust and continuous education is required for both health care providers and radiology staff.”
Potpourri of Contrast: Controversies and Myths Where Is the Actual Evidence?
Miltiadis Tembelis, Gregg Blumberg,Luis Colon-Flores et al.
Radiol Clin N Am - (2024) (in press) - “The most recent ACR guidelines no longer catalog solitary kidney as a risk factor.12 Thus, patients with a single kidney should be managed similarly to patients with 2 functional kidneys. The decision to administer or withhold IV contrast should be always made solely on the basis of the renal function, that is, based on the estimated glomerular filtration rate (eGFR), and the presence of a solitary kidney should not be used to alter this decision.”
Potpourri of Contrast: Controversies and Myths Where Is the Actual Evidence?
Miltiadis Tembelis, Gregg Blumberg,Luis Colon-Flores et al.
Radiol Clin N Am - (2024) (in press) - “Spontaneous renal hemorrhage (SRH), defined as renal hemorrhage in the absence of trauma or anticoagulation, is uncommon and is a diagnostic challenge. Accurate diagnosis requires evaluation of both the clinical presentation and imaging. Occult renal hemorrhages are especially challenging to diagnose. Given the relatively high mortality of SRH, ranging between 2.3 and 14%, early diagnosis is critical to institute lifesaving and reno-protective interventions. Common etiologies of SRH include renal neoplasms and vascular causes like vasculitis and vascular malformations. SRH can also occur in patients with chronic kidney disease from diabetic nephropathy and from acquired cystic renal disease."
Imaging review of spontaneous renal hemorrhage
Denver S. Pinto · Hannah Clode · Beatrice L. Madrazo · Fabio M. Paes · Francesco Alessandrino
Emergency Radiology (2024) 31:515–528 - “For patients with severe renal dysfunction (eGFR < 30 mL/min/1.73 m2), the risk of CI-AKI may exist, although the incidence and severity of CI-AKI associated with this risk have been overstated. Even in this higher-risk population, CI-AKI risk should not be considered an absolute contraindication to ICM administration, particularly in emergent clinical situations or circumstances in which the benefits of contrast media use outweigh risks of this clinical phenomenon.”
Risk of Acute Kidney Injury Following IV Iodinated Contrast Media Exposure: 2023 Update, From the AJR Special Series on Contrast Media
Jennifer S. McDonald, Robert J. McDonald
AJR 2024; 223:e2330037
- Purpose: To determine whether patients with a solitary kidney are at higher risk for contrast material–induced acute kidney injury (AKI) than matched control patients with bilateral kidneys.
Conclusion: Our study did not demonstrate any significant differences in the rate of AKI, dialysis, or death attributable to contrast-enhanced CT in patients with a solitary kidney versus bilateral kidneys. Is the Presence of a solitary Kidney an independent risk Factor for acute Kidney injury after contrast-enhanced CT? McDonald JS et al. Radiology 2016; 278:74–81 - “After propensity score matching, the rate of acute kidney injury (AKI) after contrast material– enhanced CT was similar between patients with solitary versus bilateral kidneys (AKI definition increase in serum creatinine [SCr] level 0.5 mg/dL odds ratio = 1.11 [95% confidence interval {CI}: 0.65, 1.86], P = .70; AKI definition increase in SCr level 0.3 mg/dL or 50% over baseline odds ratio = 0.96 [95% CI: 0.41, 2.07], P = .99).” Is the Presence of a solitary Kidney an independent risk Factor for acute Kidney injury after contrast-enhanced CT? McDonald JS et al. Radiology 2016; 278:74–81
- “The rate of emergent dialysis was rare and also not significantly different between patients with solitary versus bilateral kidneys (0.8% [two of 247 patients] vs 0.4% [three of 691 patients], respectively; odds ratio = 1.87 [95% CI: 0.16, 16.4]; P = .61).” Is the Presence of a solitary Kidney an independent risk Factor for acute Kidney injury after contrast-enhanced CT? McDonald JS et al. Radiology 2016; 278:74–81
- When is a contrast enhanced scan needed?
• unilateral renal stranding/enlargement with risk factors for renal infarct or vein thrombosis (ie, patients with dysrhythmia, thromboembolic disease history, or elevated levels of lactate dehydrogenase)
• perirenal fluid collection
• renal mass/complicated cyst
• unexplained hematuria
- “ Split bolus MDCT urography detected all proven cases of tumors of the upper urinary tract, yielding both high sensitivity and specificity. The split bolus technique has the potential to reduce both radiation dose and the number of images generated by MDCT Urography.”
Split-Bolus MDCT Urography with Synchronous Nephrographic and Excretory Phase Enhancement
Chow LC et al.
AJR 2007; 189:314-322 - “ 40 mL was administered at a rate of 2 mL/s after the unenhanced phase. After a 4-minute delay, an additional 80 mL was administered at 2 mL/s and the abdominal compression devise was inflated. The contrast enhance, breath hold abdominal phase images were acquired 120 seconds after the second contrast bolus, yielding images in synchronous nephrographic and excretory phases of enhancement.”
Split-Bolus MDCT Urography with Synchronous Nephrographic and Excretory Phase Enhancement
Chow LC et al.
AJR 2007; 189:314-322
- Renal Medullary Hyperattenuation on CT: Facts
- Normal variant and may be due to- Hydration status
- Owing to precipitation of drugs in the collecting tubules
- Possible indicator of nephrocalcinosis
- High medullary sodium chloride calcification