Whole body MRI: A predictor of adverse events in high-risk diabetic patients
Diabetes mellitus (DM) is a debilitating and costly disease. Risk assessment and progress monitoring is essential for proper clinical management. Because magnetic resonance imaging can investigate both macro- as well as micro-vascular organ changes, both of which are of significant importance in DM, the technology has the potential to serve as a screening and risk assessment tool.
But just how effective might it be? And would it be cost effective? A multi-institutional team of German researchers evaluated the predictive capability of MRI for typical diabetic adverse events, with an emphasis on macro-vascular disease. Sixty-one patients who had been diabetics for 14 to 28 years were included in the study. The patients’ medical records were followed between five and six years after a whole-body MRI examination performed at Klinikum Grosshadern of Ludwig Maximilians University in Munich where these patients were being treated at its outpatient clinic. The investigators assessed the predictive capability of MRI for recurrent events in patients with DM and described their findings in an article published online August 25, 2015 in European Radiology.
The patient cohort was evenly divided between men and women. One third had type 1 DM at the time of enrollment in the study and the remainder had type 2. Patients ranged in age from 56 to 71 years. Nearly 40% had a prior history of cardiovascular disease, 34% had cerebrovascular disease, 26% had myocardial infarction, and 5% had a stroke.
The adverse events evaluated included cardiovascular death, non-fatal myocardial infarction, coronary revascularization, cardiac arrhythmia, congestive heart failure, non-fatal stroke, carotid revascularization, nephropathy, peripheral artery disease, and retinopathy. The number of events per patient were stratified into three categories: no events, single events, or recurrent events. For subanalysis, events were also stratified regarding their anatomical origin: cardiac, cerebral, and non-cardiocerebral.
A total of 26 patients developed 39 events, of whom eight (13%) developed recurrent events. Patients with recurrent events tended to be older, had a history of cardiovascular disease, and had type 2 DM. Women had more recurrent events than men.
Effectiveness of MRI as a predictor
Lead author and radiologist Robert C. Bertheau, M.D., and co-authors determined that the presence of delayed contrast enhancement in myocardial tissue representing scar tissue, left ventricular hypo-/akinsia, left ventricular ejection fraction, carotid artery stenosis, and the number of stenosed arteries was associated with a stepwise higher burden of adverse events representing a worse clinical course. The authors reported that even after adjustement for clinical characteristics, the majority of MR findings remained independently associated with recurrent events.
Regarding the strongest MR predictors, the presence of carotid stenosis, the number of stenosed peripheral vessels, and decreased left-ventricular ejection fraction yielded independently of each other significant value as predictors for recurrent events. Furthermore, the vessel scor, a summary measure derived from the number of diseased vessel segments and the degree of arteriosclerotic change, were strong predictors for recurrent events.
In a subanalysis regarding anatomical relatedness beween MR findings and future events, cardiac MR findings were shown to significantly predict more strongly future cardiac events, and cerebral MR findings were shown to predict more strongly future cerebral events. MR findings of the peripheral arteries were also predictive for cardiac events, but not for cerebral events.
Affordability of MRI as an adverse event predictor for high risk diabetic patients
A whole-body MRI examination is expensive. Is it affordable? Applied Radiology asked this question of senior author Christopher L. Schlett, M.D., section head of cardiac imaging in the Department of Diagnostic and Interventional Radiology at University Hospital Heidelberg. He responded: “At the current time, we do not have any evidence with respect to cost-effectiveness of whole-body MRI in DM. With the work we are undertaking, it becomes more likely that whole-body MRI can provide a clinical benefit that outweighs the additional cost.”
“Effective, personalized prevention strategies in high risk diabetic patients have the great potential of being cost-effective,” Dr. Schlett said. “However, two requirements must be fulfilled. We need precise risk stratification and effective prevention tools. Further research is needed to evaluate which prevention strategies are most effective in these patients. At the moment, a strategy remains hypothetically; however optimization of diabetic treatment as well as maximum elaboration of arteriosclerotic prevention strategies as recommended by the American College of Cardiology and the American Hospital Association seem logical.”
“Whole body MRI imaging is only being ordered for diabetic patients in case of contradicting assessment. In these cases, we try to identify what kind of treatment or prevention should be offered,” he added.
Dr. Schlett concluded, saying “Although the concept of recurrent events is rarely used today, we expect that it will be more prominent in the future. Chronification of disease by turning fatal into non-fatal events because of improved acute care without curing disease entirely is not only a challenge to DM. To provide additional clinical evidence and to develop novel statistical analysis methods for recurrent events will be one of the important topics in the future.”
REFERENCE
- Bertheau RC, Bamberg F, Lochner E et al. Whole-Body MR Imaging Including Angiography: Predicting Recurrent Events in Diabetics. Eur Radiol. Published online August 25, 2015.