Clinical use of differential nuclear medicine modalities in patients with ATTR amyloidosis

Histological proof remains the gold standard for the diagnosis of amyloidosis. Nuclear medicine imaging techniques are able to determine the amyloid load in the body. Currently, the best imaging modality is I-123-SAP scintigraphy. This modality has high sensitivity for detecting amyloid deposits in all amyloid subtypes. Involvement of liver and spleen can be visualized before clinical signs are present. The addition of single photon emission computed tomography improves the differentiation of overlying organs. However, I-123-SAP is not FDA approved. Its availability is limited to two centres in Europe. Furthermore, it is not suitable for imaging cardiac involvement of amyloidosis, due to movement, blood-pool content and lack of fenestrated endothelial in the myocardium. Phosphate derivates labelled with Tc-99m, are able to detect calcium compounds in cardiac amyloidosis. Finally, I-123-MIBG, an analogue of norepinephrine, can detect cardiac sympathetic innervation abnormalities as a consequence of amyloid deposits. Both these last techniques seem to be able to detect cardiac involvement before echocardiographic parameters are present. We illustrate the clinical use of these modalities with two patients with ATTR type amyloidosis

Comparison of magnetic resonance enteroclysis and capsule endoscopy with balloon-assisted enteroscopy in patients with obscure gastrointestinal bleeding

Background and study aims: New modalities are available for visualization of the small bowel in patients with possible obscure gastrointestinal bleeding (OGIB), but their performance requires further comparison. This study compared the diagnostic yield of magnetic resonance enteroclysis (MRE) and capsule endoscopy in patients with OGIB, using balloon-assisted enteroscopy (BAE) as the reference standard. Patients and methods: Consecutive consenting patients who were referred for evaluation of OGIB were prospectively included. Patients underwent MRE followed by capsule endoscopy and BAE. Patients with high grade stenosis at MRE did not undergo capsule endoscopy. The reference standard was BAE findings in visualized small-bowel segments and expert panel consensus for segments not visualized during BAE. Results: Over a period of 26 months, 38 patients were included (20 female [53 %]; mean age 58 years, range 28-75 years). Four patients (11 %) did not undergo capsule endoscopy due to high grade small-bowel stenosis at MRE (n=3; 8%) or timing issues (n=1; 3%). Capsule endoscopy was non-diagnostic in one patient. The reference standard identified abnormal findings in 20 patients (53 %). MRE had sensitivity, specificity, and positive and negative likelihood ratios of 21%, 100%, infinity, and 0.79, Conclusion: Capsule endoscopy performed better than MRE in the detection of small-bowel abnormality in patients with OGIB. MRE may be considered as an alternative for the initial examination in patients with clinical suspicion of small-bowel stenosis