Iodinated contrast media and their adverse reactions

Challenges, controversies, and hot topics in pulmonary embolism imaging

OBJECTIVE

The purpose of this article is to discuss the diagnostic role of pulmonary CT angiography (CTA) in the workup of pulmonary embolism (PE), including specific populations, and issues such as pulmonary CTA combined with indirect CT venography; radiation dose considerations; the management of isolated subsegmental PE; and new technologic developments, such as dual-source/dual-energy pulmonary CTA.

CONCLUSION

The role of pulmonary CTA will continue to grow with the emergence of MDCT and dual-energy CT and their improved capabilities. However, the need for any given CT examination should always be justified on the basis of the individual patient's benefits and risks.

Contrast-enhanced CT for localizing compressive thoracolumbar intervertebral disc extrusion

Thoracolumbar intervertebral disc extrusion is a common disease in dogs. Surgical decompression of the spinal cord is the preferred treatment. Localization of the compressive material is critical for surgical planning. Myelography has been used for localizing extruded disc material, but this procedure carries risk of complications. Computed tomography (CT) is becoming more available for use in veterinary medicine and CT myelography is used for localization of extruded disc material. This report compares CT with intravenous contrast medium and CT myelography for identifying extruded intervertebral discs. CT with intravenous contrast medium is as effective as CT myelography for determining level and laterality of compressive disc extrusions.

Comparison of dynamic contrast-enhanced MRI and dynamic contrast-enhanced CT biomarkers in bladder cancer

Dynamic contrast-enhanced MRI (DCE-MRI) is frequently used to provide response biomarkers in clinical trials of novel cancer therapeutics but assessment of their physiological accuracy is difficult. DCE-CT provides an independent probe of similar pharmacokinetic processes and may be modeled in the same way as DCE-MRI to provide purportedly equivalent physiological parameters. In this study, DCE-MRI and DCE-CT were directly compared in subjects with primary bladder cancer to assess the degree to which the model parameters report modeled physiology rather than artefacts of the measurement technique and to determine the interchangeability of the techniques in a clinical trial setting. The biomarker K(trans) obtained by fitting an extended version of the Kety model voxelwise to both DCE-MRI and DCE-CT data was in excellent agreement (mean across subjects was 0.085 ± 0.030 min(-1) for DCE-MRI and 0.087 ± 0.033 min(-1) for DCE-CT, intermodality coefficient of variation 9%). The parameter v(p) derived from DCE-CT was significantly greater than that derived from DCE-MRI (0.018 ± 0.006 compared to 0.009 ± 0.008, P = 0.0007) and v(e) was in reasonable agreement only for low values. The study provides evidence that the biomarker K(trans) is a robust parameter indicative of the underlying physiology and relatively independent of the method of measurement.

Safety, efficacy, and indications of beta-adrenergic receptor blockade to reduce heart rate prior to coronary CT angiography

For selected indications, coronary computed tomographic (CT) angiography is an established clinical technology for evaluation in patients suspected of having or known to have coronary artery disease. In coronary CT angiography, image quality is highly dependent on heart rate, with heart rate reduction to less than 60 beats per minute being important for both image quality and radiation dose reduction, especially when single-source CT scanners are used. β-Blockers are the first-line option for short-term reduction of heart rate prior to coronary CT angiography. In recent years, multiple β-blocker administration protocols with oral and/or intravenous application have been proposed. This review article provides an overview of the indications, efficacy, and safety of β-blockade protocols prior to coronary CT angiography with respect to different scanner techniques. Moreover, implications for radiation exposure and left ventricular function analysis are discussed.

Fusion imaging: a novel staging modality in testis cancer

Objective: Computed tomography and chest radiographs provide the standard imaging for staging, treatment, and surveillance of testicular germ cell neoplasms. Positron emission tomography has recently been utilized for staging, but is somewhat limited in its ability to provide anatomic localization. Fusion imaging combines the metabolic information provided by positron emission tomography with the anatomic precision of computed tomography. To the best of our knowledge, this represents the first study of the effectiveness using fusion imaging in evaluation of patients with testis cancer.

Methods: A prospective study of 49 patients presenting to Walter Reed Army Medical Center with testicular cancer from 2003 to 2009 was performed. Fusion imaging was compared with conventional imaging, tumor markers, pathologic results, and clinical follow-up.

Results: There were 14 true positives, 33 true negatives, 1 false positive, and 1 false negative. Sensitivity, specificity, positive predictive value, and negative predictive value were 93.3, 97.0, 93.3, and 97.0% respectively. In 11 patient scenarios, fusion imaging differed from conventional imaging. Utility was found in superior lesion detection compared to helical computed tomography due to anatomical/functional image co-registration, detection of micrometastasis in lymph nodes (pathologic nodes < 1cm), surveillance for recurrence post-chemotherapy, differentiating fibrosis from active disease in nodes < 2.5cm, and acting as a quality assurance measure to computed tomography alone.

Conclusions: In addition to demonstrating a sensitivity and specificity comparable or superior to conventional imaging, fusion imaging shows promise in providing additive data that may assist in clinical decision-making.

Value of contrast-enhanced ultrasonography in assessing the vascularity of liver metastases: comparison with contrast-enhanced computed tomography

OBJECTIVE

The purpose of this study was to compare the capability of contrast-enhanced ultrasonography (CEUS) and contrast-enhanced computed tomography (CECT) in evaluating the vascularity of liver metastases.

METHODS

Both CEUS and CECT examinations were performed on 70 patients with liver metastases, which were from colon carcinoma in 31, rectal carcinoma in 17, pancreatic carcinoma in 5, and others in 17. In patients with multiple lesions, the most easily observed lesion was selected as the target lesion for evaluation of vascularity.

RESULTS

Peak enhancement of the target lesion during the arterial phase was characterized as hyperenhancement, isoenhancement, hypo-enhancement, and nonenhancement in 61 (87.1%), 6 (8.6%), 3 (4.3%), and 0 (0%) patients on CEUS, respectively, and in 52 (74.3%), 8 (11.4%), 8 (11.4%), and 2 (2.9%) on CECT. Contrast-enhanced ultrasonography showed more lesions with hyperenhancement than CECT (P < .01). The enhancement pattern during the arterial phase was homogeneous, inhomogeneous, and rimlike in 30 (42.9%), 16 (22.9%), and 24 (34.2%) patients on CEUS and in 13 (18.6%), 8 (11.4%), and 49 (70%) on CECT. Contrast-enhanced ultrasonography revealed more lesions with homogeneous enhancement than CECT (P < .01). Contrast-enhanced ultrasonography showed dysmorphic vessels in 33 patients (47.1%) during the arterial phase, whereas CECT showed dysmorphic vessels in 27 (38.6%; P < .01). Contrast-enhanced ultrasonography showed hypervascular lesions in 58.6% of patients, whereas CECT showed hypervascular lesions in 12.9% (P < .01).

CONCLUSIONS

Contrast-enhanced ultrasonography was superior to CECT in assessing the vascularity of liver metastases.

[New nursing diagnoses in imaging: submission to NANDA International]

The present work reports the experiment on the creation and submission to North American Nursing Diagnosis Association International (NANDA-I) of Nursing Diagnosis in the imageology area: "Adverse Reaction to Iodinated Contrast Media" and "Risk of Adverse Reaction to Iodinated Contrast Media". For this experiment the method of integrative revision of literature was utilized associated with the experience in clinical practice. The document for submission was elaborated according to guidance offered by NANDA-I and sent for appreciation to the Diagnosis Development Committee. The risk diagnose was approved and the real diagnose is still in evaluation process by the Diagnosis Development Committee. With this experiment we hope to motivate Brazilian nurses to contribute to the taxonomy of NANDA-I and participate in the building ofnursing knowledge.

Toxicity of MRI and CT contrast agents

Anatomical and physiological imaging using CT and MRI are playing a critical role in patients' diagnosis, disease characterization and treatment planning. CT- and MRI-based protocols increasingly require an injection of iodinated CT and gadolinium (Gd)-based MRI contrast media. Although routinely used in clinical practice, iodinated and to a less extent Gd-based contrast media possess side effects: life-threatening contrast-induced nephropathy (CIN) is associated with CT and nephrogenic systemic fibrosis (NSF) with MRI contrast agents. CIN is defined as an acute decline in renal functions (serum creatinine increase > 0.5 mg/dl) after administration of iodinated contrast media. Patients with moderate-to-severe chronic kidney disease are considered the highest risk group for development of CIN. CIN is more common with ionic high-osmolar contrast CT media. NSF is a rare condition characterized by the formation of connective tissue in the skin and systemically in the lung, liver, heart and kidney. Patients with end stage kidney disease, acute kidney injury and stage 4-5 chronic kidney disease are at a high risk for NSF. The nonionic linear Gd-chelates are associated with the highest risk of NSF. This review summarizes the incidence, symptoms, safety profile of various CT and MRI contrast agents based on their physiochemical properties.

Imaging atoms in medicine

The innovations in science and technology have allowed researchers to look inside the human body. In some cases, like MRI, the protons present in the body generate enough signal for an image. However, the employ of certain atoms, metallic or non-metallic, enable detection through different imaging techniques (computed tomography, nuclear imaging, ultrasound or optical imaging), and improve the quality of the images. Here we discuss the different imaging atoms used depending on the imaging technique and the new possible imaging atoms for medical applications.