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Imaging of dialysis-related amyloid (AB-amyloid) deposits with 131I-beta 2-microglobulin
J Floege1, W Burchert, A Brandis
1Department of Nephrology, Medizinische Hochschule Hannover, Federal Republic of Germany.
Abstract:
The diagnosis of dialysis-related amyloid (AB-amyloid) has been based usually on clinical and radiological criteria. Following the discovery that beta 2-microglobulin was the major protein of this amyloid, we isolated and radiolabelled uremic plasma beta 2-microglobulin. After intravenous injection, gamma-camera images of selected joint areas were obtained from 42 patients who were on regular hemodialysis therapy. Positive scans involving the shoulder, hip, knee and carpal regions were found in 13 of 14 patients treated for more than 10 years and 10 of 16 patients treated for 5 to 10 years. Patients treated for less time had negative scans. Specificity was indicated by negative scans in non-amyloid inflammatory lesions in control hemodialysis patients. Up to 48-fold tracer enrichment was detected in excised AB-amyloid containing tissue as compared to amyloid-free tissue. These findings suggest that circulating radiolabelled beta 2-microglobulin is taken up by the amyloid deposits. This method may non-invasively detect tissue infiltrates of amyloid. It may also permit prospective evaluation of the efficacy of prophylactic dialysis strategies which are designed to prevent or delay the onset of this complication of long-term dialysis.
Insights
Researchers developed a new imaging technique using radiolabeled beta 2-microglobulin to detect dialysis-related amyloid (AB-amyloid) deposits. This method shows promise for non-invasive diagnosis and evaluating preventative dialysis strategies.
Area of Science:
- Nephrology
- Medical Imaging
- Biochemistry
Background:
- Dialysis-related amyloid (AB-amyloid) diagnosis traditionally relies on clinical and radiological assessments.
- Beta 2-microglobulin has been identified as the primary protein component of AB-amyloid.
Purpose of the Study:
- To develop and evaluate a non-invasive imaging method for detecting AB-amyloid deposits using radiolabeled beta 2-microglobulin.
- To assess the correlation between hemodialysis duration and amyloid deposition using the novel imaging technique.
Main Methods:
- Isolation and radiolabeling of beta 2-microglobulin from uremic plasma.
- Intravenous injection of the radiotracer in 42 hemodialysis patients.
- Gamma-camera imaging of joint areas to detect tracer uptake in amyloid deposits.
Main Results:
- Positive scans were observed in 13/14 patients with >10 years of dialysis and 10/16 patients with 5-10 years of dialysis.
- Patients with shorter dialysis durations showed negative scans.
- Significant tracer enrichment (up to 48-fold) was found in excised amyloid-containing tissue compared to non-amyloid tissue.
Conclusions:
- Circulating radiolabeled beta 2-microglobulin is effectively taken up by AB-amyloid deposits.
- This imaging approach offers a non-invasive method for detecting tissue infiltrates of amyloid.
- The technique may enable prospective evaluation of prophylactic dialysis strategies to prevent AB-amyloidosis.