Fluctuations in eGFR in relation to unenhanced and enhanced MRI and CT outpatients.

OBJECTIVE: To study fluctuations in estimated glomerular filtration rate (eGFR) in relation to contrast medium (CM) enhanced magnetic resonance imaging (MRI) and computed tomography (CT) compared to control groups in outpatients. MATERIALS AND METHODS: eGFR was determined right before the imaging procedure and three days later at the department or at the patient's home. The iodine-based and gadolinium-based contrast media were the same as used for all other examinations at the department. RESULTS: A total of 716 patients completed the study. There was a statistically significant, but not clinically relevant rise in eGFR after three days in all four groups. The average eGFR variation was 4.8 ml/min/1.73 m(2). There were large variations in eGFR between the two measurements in 45.8% of the patients as they had a change greater than ± 10 ml/min/1.73 m(2). Only three patients fulfilled the contrast-induced nephropathy (CIN) requirement when the definition s-creatinine ≥ 44 µmol/l (0.5mg/dl) was used. CONCLUSIONS: eGFR in outpatients undergoing MRI or CT did vary independently of whether the patient received contrast or not. The findings probably reflect the natural variations in s-creatinine levels. This should be taken into consideration when CIN is studied.

Can a structured questionnaire identify patients with reduced renal function?

OBJECTIVES: To evaluate a structured questionnaire in identifying outpatients with renal dysfunction before MRI or CT in various age groups. METHODS: All patients completed a questionnaire with five risk factors indicating renal dysfunction: renal disease, renal surgery, hypertension, gout and diabetes. Serum creatinine determined by the point-of-care (POC) technique and estimated glomerular filtration (eGFR) rate was calculated using CKD-EPI equation. RESULTS: A total of 1,467 patients were enrolled. Thirty-four patients (2%) had an eGFR <30 ml/min/1.73 m(2) and 123 (8%) had an eGFR <45 ml/min/1.73 m(2). Among 55% of the 1,467 patients reporting at least one risk factor, 30 (4%) had an eGFR <30 ml/min/1.73 m(2) and 105 (13%) had an eGFR <45 ml/min/1.73 m(2). Among 651 patients not reporting a risk factor, 4 (0.6%) had an eGFR <30 ml/min/1.73 m(2) and 18 (3%) had an eGFR <45 ml/min/1.73 m(2). All four patients were >70 years old, and 12 of the 18 patients were >70 years old. CONCLUSION: The questionnaire used in patients <70 years old and determination of eGFR in patients >70 years old identified all patients with an eGFR between 30 and 45 ml/min/1.73 m(2) except 0.4%. KEY POINTS: • A questionnaire can adequately identify patients under 70 with renal dysfunction • 8% of patients referred to CT/MRI have an eGFR <45 ml/min/1.73 m (2) • 55% reported risk factors, but renal dysfunction was only found in 13% • Patients over 70 years should have eGFR determined before CT • eGFR determination is not beneficial when stable MRI agents are used.

Late adverse events after enhanced and unenhanced MRI and CT: a prospective study.

Prospective evaluation of frequency of late and very late adverse events in patients undergoing enhanced or unenhanced magnetic resonance imaging (MRI) or computed tomography (CT). The imaging procedure was performed according to the protocols of the department. All patients were contacted 3 days after their imaging procedure for the occurrence of late adverse events (LAEs) and a month later for the occurrence of very late adverse events (VLAEs) using a structured questionnaire. A total of 1042 (71%) among 1473 patients completed both the 3-day and 1-month questionnaire. The incidence of LAEs was significantly higher in the enhanced MRI (38%) and CT (27%) groups than unenhanced MRI (20%) and CT (16%) groups. The frequency of nausea, dizziness, abdominal pain and diarrhoea was significantly higher in the enhanced MRI group than in the MRI control group, while taste sensation was reported more frequent in the enhanced CT group than in the CT control group. The incidence of VLAEs was significantly higher in the enhanced CT (21%) than unenhanced CT group (13%). The same LAEs and VLAEs were reported in all four groups. LAEs and VLAEs were reported more often in patients with allergy in both the enhanced and unenhanced groups. The incidence of LAEs and VLAEs was higher in the enhanced groups than in the unenhanced groups. The most reported adverse events in the enhanced groups were also reported in the unenhanced groups. Patients with allergy reported LAE and VLAE more often. This suggests that adverse events may not always be caused by the contrast media.