Gadolinium-based contrast agents built of DO3A-pyridine scaffold:Precisely tuning carboxylate group for enhanced magnetic resonance imaging

It is greatly desired to develop novel gadolinium-based contrast agents(GBCAs)as improved platforms for magnetic resonance imaging(MRI).Herein,we report the syntheses of a series of nonionic cyclenbased GBCAs by precisely tuning carboxylate group on DO3A-pyridine scaffold.[Gd-DO3A-4cp]is isolated which adopts an octadentate coordination mode with a free carboxylate group at 4-position of pyridine.It shows the r_(1)relaxivity of 5.8(mmol/L)^(-1)s^(-1)(3 T,25℃),which is 75%higher than 3.3(mmol/L)^(-1)s^(-1)of the clinic used[Gd-DOTA].The possible mechanisms behind the enhanced relaxivity are investigated and proposed by structure-property relationship studies.After validation of low cytotoxicity and considerable kinetic inertness,in-vivo studies are further examined,demonstrating its good MRI performance,biodistribution as well as the way of excretion.

Nephrogenic systemic fibrosis:A frivolous entity

Gadolinium-based contrast agents(GBCAs)used in magnetic resonance imaging are vital in providing enhanced quality images,essential for diagnosis and treatment.Nephrogenic systemic fibrosis(NSF)with GBCAs has been a deterrent for the physician and has led to avoidance of these agents in patients with impaired kidney function.NSF is a progressive debilitating multisystem condition described classically in patients with renal insufficiency exposed to gadolinium contrast media.It is characterized by an induration and hardening of the skin.NSF is described to first involve the extremities and can imperceptibly involve internal organs.Lack of therapeutic interventions to treat NSF makes it more challenging and warrants deep insight into the pathogenesis,risk factors and treatment strategies.

Pathophysiology of nephrogenic systemic fibrosis:A review of experimental data

Since the association between nephrogenic systemic fibrosis(NSF) and gadolinium contrast agents(Gd-CAs) was suggested in 2006,several experimental studies have been published to elucidate the role of these agents in the pathogenesis of NSF.Low stability Gd-CAs have a stimulant effect on human skin and fibroblasts in culture and modulate the production of collagen by these cells.Low stability agents have also induced NSFlike skin changes in a rat model with normal renal function after multiple repeat administrations.The role of the 5/6 subtotal nephrectomy rat model in investigating NSF remains under evaluation.

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.

Acute non-renal adverse events after unenhanced and enhanced computed tomography and magnetic resonance imaging

Aim: Investigating the incidence of non-renal acute adverse events (AAEs) in patients undergoing unenhanced or enhanced computed tomography (CT) or magnetic resonance (MR) (four groups) using the ac- tive interview-method. Methods: The imaging procedure followed the standards of the department. Furthermore, the iodine-based (nonionic monomer) and gadolinium-based (cyclic) contrast agent was the same as used for all other examinations in the department. All patients were interviewed for 72 hours after the MR or CT examination regarding occurrence of AAEs using a structured questionnaire. Results: A total of 1358 patients (259 with enhanced MR, 434 with unenhanced MR, 450 with enhanced CT and 215 with unenhanced CT) were enrolled. AAEs were significantly higher (P unenhanced MR [39 (9.0%)] and CT [5 (2.3%)] groups. Dizziness was significantly [19 (7.3%), (P frequent in the enhanced MR. The same AAEs were reported in both contrast groups and control groups. Conclusion: AAEs which are mainly considered to be caused by the contrast medium are also experienced by patients undergoing CT or MR without contrast. Enhanced MR is correlated with more reactions than unenhanced MR and enhanced CT. Dizziness was reported more frequently after MR than CT, both with and without contrast;more patients were CNS examined with MR and with CT.