Amyloid imaging mismatch

An 82-year-old man with suspected systemic amyloidosis and complete atrioventricular block underwent vascular biopsy during his pacemaker implantation with pathology showing amyloid deposits. 99mTc-aprotinin SPECT revealed increased radiotracer uptake along the left ventricular wall, consistent with cardiac amyloidosis. 11C-PiB PET/CT performed for the evaluation of amyloid deposits in the brain showed findings suggestive of Alzheimer disease without abnormal radiotracer concentration in the myocardium to match the 99mTc-aprotinin SPECT findings. Dynamic PET images showed increased 11C-PiB concentration in the left ventricular myocardium at 2 minutes after injection, with subsequent tracer clearance by approximately 5 minutes, consistent with normal 11C-PiB biodistribution.     

Whole-body fluorodeoxyglucose positron emission tomography/computed tomography in patients with active polymyalgia rheumatica: evidence for distinctive bursitis and large-vessel vasculitis

Objectives

To investigate fluorodeoxyglucose (FDG) accumulation in large joints, bursas, and large vessels in patients with polymyalgia rheumatica (PMR) using 18-FDG positron emission tomography/computed tomography (PET/CT) and to differentiate PMR from similar diseases.

Methods

Fourteen untreated patients with active PMR and 17 control patients with rheumatoid arthritis (n?=?11) or other active rheumatic diseases (n?=?6) underwent 18-FDG PET/CT. FDG uptake in large joints, bursas and vertebral spinous processes was evaluated by calculating maximum standardised uptake values and by visual scoring (scale 0–4). PET scan images were scored in seven vascular regions, and total vascular scores (range 0–21) were calculated.

Results

Polymyalgia rheumatica patients showed increased FDG uptake in ischial tuberosities, greater trochanters, and lumbar spinous processes. Positive results at two or more of these sites showed high sensitivity (85.7%) and specificity (88.2%) for the diagnosis of PMR, and shoulder or hip-joint involvement showed low disease specificity. High FDG accumulations were found in the aortas and subclavian arteries of two PMR patients who were asymptomatic for temporal arteritis and scanty synovium and perisynovium, based on FDG uptake. PET/CT images of the 12 PMR patients without apparent vascular involvement showed synovitis and/or perisynovitis.

Conclusions

Fluorodeoxyglucose-PET/CT may be useful for the detection of PMR lesions, which are difficult to identify using other methods.