Intraindividual comparison of gadolinium- and iodine-enhanced 64-slice multidetector CT pulmonary angiography for the detection of pulmonary embolism in a porcine model

Ultrasound-guided carotid angioplasty and stenting in a patient with iodinated contrast allergy: A case report

BACKGROUND

Ischemic stroke is an entity with high incidence, morbidity, and mortality rates. Carotid artery stenosis is an important and independent risk factor for ischemic stroke. The three current approaches for treating carotid artery stenosis are drug treatment, carotid endarterectomy (CEA), carotid angioplasty and stenting (CAS). The approach is chosen based on the degree of stenosis. CEA or CAS could have been chosen for the current patient, who had severe carotid stenosis and an iodinated contrast allergy. After thoroughly communicating with the patient, the patient chose CAS for treatment. Therefore, we performed ultrasound-guided CAS to avoid the use of iodinated contrast.

CASE SUMMARY

The main symptoms of the patient were numbness and weakness of the left limb. Computed tomography angiography of the head and neck at another hospital indicated multiple sites of stenosis in the arteries of the head and neck. The patient requested CAS for treatment but was allergic to iodinated contrast media. Thus, routine digital subtraction angiography (DSA) with iodinated contrast could not be used for the procedure. The diagnosis of this patient was as follows: (1) Right parietal lobe cerebral infarction; (2) multiple sites of stenosis in the arteries of the head and neck (severe stenosis of the right internal carotid artery, severe stenosis of the right subclavian artery); (3) right subclavian steal syndrome; and (4) hypertension (stage 3, high risk). The interventions included routine treatment for cerebral infarction, oral administration of clopidogrel (75 mg qd) and aspirin (100 mg qd), ultrasound-guided CAS, and postoperative follow-up. Postoperative color Doppler ultrasound and cerebrovascular magnetic resonance angiography of the carotid artery showed good vascular recovery, and the postoperative follow-up indicated a good prognosis.

CONCLUSION

This case study suggests that ultrasound-guided endovascular treatment is a potential option for patients with contraindications to the iodinated contrast agents used in DSA-guided surgery, although excellent surgical operating skills are needed.

Perfusion-ventilation CT via three-material differentiation in dual-layer CT: a feasibility study

Dual-Energy Computed Tomography is of significant clinical interest due to the possibility of material differentiation and quantification. In current clinical routine, primarily two materials are differentiated, e.g., iodine and soft-tissue. A ventilation-perfusion-examination acquired within a single CT scan requires two contrast agents, e.g., xenon and gadolinium, and a three-material differentiation. In the current study, we have developed a solution for three-material differentiation for a ventilation-perfusion-examination. A landrace pig was examined using a dual-layer CT, and three scans were performed: (1) native; (2) xenon ventilation only; (3) xenon ventilation and gadolinium perfusion. An in-house developed algorithm was used to obtain xenon- and gadolinium-density maps. Firstly, lung tissue was segmented from other tissue. Consequently, a two-material decomposition was performed for lung tissue (xenon/soft-tissue) and for remaining tissue (gadolinium/soft-tissue). Results reveal that it was possible to differentiate xenon and gadolinium in a ventilation/perfusion scan of a pig, resulting in xenon and gadolinium density maps. By summation of both density maps, a three-material differentiation (xenon/gadolinium/soft tissue) can be performed and thus, xenon ventilation and gadolinium perfusion can be visualized in a single CT scan. In an additionally performed phantom study, xenon and gadolinium quantification showed very accurate results (r > 0.999 between measured and known concentrations).