Half-Dose Gd-BOPTA Effective in Assessing Synovial Enhancement

Becky McCall

March 16, 2011

March 16, 2011 (Vienna, Austria) — Half-dose gadolinium, also known as Gd-BOPTA (MultiHance, Bracco), with 3-Tesla magnetic resonance imaging (MRI) is sufficient for the assessment of synovial enhancement of the hands in patients with early rheumatoid arthritis (RA), according to a study presented here at the European Congress of Radiology 2011.

Claudia Schueller-Weidekamm, MD, from the Medical University of Vienna, Austria, and her team set out to determine whether a full dose of Gd-BOPTA is necessary for this purpose, or whether a half-dose will suffice.

It is recognized that MRI can aid early diagnosis of RA, and that the earlier the disease is diagnosed and treated effectively, the better the patient's prognosis, Dr. Schueller-Weidekamm said. She pointed out that synovitis is a predictive factor for bone erosions in patients with RA, and that contrast-enhanced MRI is a sensitive and specific way to evaluate active synovitis.

"We want to lower the cost of contrast agents and reduce the risks associated with contrast media, [which] can be harmful to the kidneys, potentially causing nephrogenic systemic fibrosis. . .  especially in patients with a low renal function [those with a creatinine clearance below 30 mL/min per 1.73 m2]. Contrast media is contraindicated in these patients," Dr. Schueller-Weidekamm pointed out.

Previous studies have examined half-dose contrast media in the brain, kidneys, and liver, but this is the first such study in RA. Thirty patients (26 women) with a mean age of 47 years who had early and active RA of the hand or finger joints and a Disease Activity Score (DAS 28) greater than 3.2 were studied. All patients were examined by a clinician before ultrasound was performed, and active synovitis was detected in all patients.

Dr. Schueller-Weidekamm performed a scan of one hand and wrist, on the side with the most severe RA, using a 3-Tesla high-resolution MRI (coronal T1-weighted turbo spin echo, coronal short-tau inversion recovery, transverse T2-weighted spin echo). Half-dose Gd-BOPTA contrast agent was used (0.05 mmol/kg per body weight), and after a second application of 0.05 mmol/kg per body weight, a full-dose image was performed.

Contrast enhancement was measured in inflamed synovial tissue in exactly the same slice on half- and full-dose contrast-enhanced sequences. Statistical analysis was then used to identify differences and correlations of signal intensities between half-dose and full-dose contrast-enhanced sequences.

"We found that it is possible to give a half dose of Gd-BOPTA and see exactly the same pathologies [as with] the full dose. We didn't miss any additional pathologies, and we found a very high correlation between half-dose and full-dose signal intensities with contrast media," reported Dr. Schueller-Weidekamm.

She concluded that half-dose Gd-BOPTA is sufficient for the assessment of synovial enhancement in patients with early RA with 3-Tesla MRI; no additional information was obtained with full-dose Gd-BOPTA. She added that despite ultrasound being more commonly used to assess synovitis, there is definitely a place for MRI in RA assessment.

"Ultrasound is fine for the detection of synovitis, but you cannot see bone marrow edema with ultrasound, so MRI is needed in dedicated cases. Bone marrow edema reported by MRI is a kind of predictive factor of bone erosions. . . . MRI has advantages over ultrasound, although it is the most expensive technique."

In the future, Dr. Schueller-Weidekamm would like to investigate the use of 1.5-Tesla for imaging early RA. "In my opinion, the reduction of Gd-BOPTA from full dose to half dose should be applicable not only for 3-Tesla scans, but also for 1.5-Tesla scans, although it would be helpful to conduct a study to confirm this. I recommend always performing follow-up examinations in RA patients in the same MRI unit. If the dose of Gd-BOPTA is halved in the follow-up MRI examination, the signal intensities of the inflamed synovial tissue with the half and full dose can be compared, because we have a special formula to convert the half dose to the full dose," she explained.

Georgios Mantzikopoulos, MD, from KAT General Hospital, Athens, Greece, the session moderator, said that "it's very interesting that we can do conclusive imaging studies in rheumatoid arthritis of the enhancement of synovium with [a] lower dose of gadolinium than that which we are used to administering."

Maria Navallas, MD, from University Hospital 12th of October, Madrid, Spain, also commented on Dr. Schueller-Weidekamm's presentation. "I find full-dose very effective, but I haven't used the half-dose. If it really works, then that's great, because it is more economical and, of course, it is better for the patients because contrast agent isn't good for patients, and we'd prefer to avoid using so much if feasible," she said.

Dr. Schueller-Weidekamm received the Gd-BOPTA from Bracco, but the manufacturer did not fund the study. Dr. Navallas and Dr. Mantzikopoulos have disclosed no relevant financial relationships.

European Congress of Radiology (ECR) 2011: Abstract B-604. Presented March 7, 2011.

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