Long-Term Metabolic Assessment of Cryopreserved Sternal Allograft: A Case Series.

BACKGROUND: Sternal resection and reconstruction with cryopreserved allografts provides a safe alternative to traditional methods of anterior chest wall reconstruction. Despite favorable results, successful integration of the graft sternum has never been demonstrated owing to the invasiveness of bone biopsy. We describe our experience of using 18F-sodium fluoride positron emission tomography/computed tomography scans as a noninvasive method of evaluating graft integration. METHODS: Seven patients underwent surgery and radiologic follow-up. Surgical indications were sternal metastases (n = 5) and sternal dehiscence (n = 2). Sternal reconstruction was performed using a cryopreserved cadaveric sternal allograft fixed in place with titanium plates and screws. Follow-up with 18F-sodium fluoride positron emission tomography/computed tomography scans was performed at 1 and 2 years after surgery. RESULTS: Three patients underwent total sternectomy. Two underwent partial upper sternectomy involving the manubrium, clavicle (1 patient only), and upper sternal body; and 2 had partial sternectomy of the sternal body and xiphoid process. Focal tracer accumulation occurred at the junctions between native bone and graft bone. The median maximum standardized uptake value at 1 year was 16.8 (range, 11.2 to 37.9; interquartile range, 13.6 to 19.4), and at 2 years it was 10.8 (range, 6.1 to 30.2; interquartile range, 8.9 to 15.1). In 6 cases accumulation was lower at the second scan, whereas in 1 patient the accumulation was higher at the second scan. CONCLUSIONS: Sternal reconstruction with cryopreserved allograft is safe and well tolerated. The 18F-sodium fluoride positron emission tomography/computed tomography scans are a useful and promising noninvasive method of demonstrating the metabolic activity of the graft and its incorporation into the host skeleton during follow-up.

Does the etiology of cardiac amyloidosis determine the myocardial uptake of [18F]-NaF PET/CT?

Cardiac amyloidosis (CA) leads to variable degrees of myocardial infiltration with a final echocardiographic phenotype of "hypertrophy." Although many non-invasive imaging techniques (MRI, CT, scintigraphy, PET) are useful, the definitive diagnosis is still based on myocardial histology. We explored the possible role of [18F]-NaF PET/CT in the diagnosis of this disease in two cases with wild-type (ATTRwt) or mutant (ATTRm) Ile68Leu transthyretin (TTR)-related CA.

Nonbiopsy Diagnosis of Cardiac Transthyretin Amyloidosis.

BACKGROUND: Cardiac transthyretin (ATTR) amyloidosis is a progressive and fatal cardiomyopathy for which several promising therapies are in development. The diagnosis is frequently delayed or missed because of the limited specificity of echocardiography and the traditional requirement for histological confirmation. It has long been recognized that technetium-labeled bone scintigraphy tracers can localize to myocardial amyloid deposits, and use of this imaging modality for the diagnosis of cardiac ATTR amyloidosis has lately been revisited. We conducted a multicenter study to ascertain the diagnostic value of bone scintigraphy in this disease. METHODS AND RESULTS: Results of bone scintigraphy and biochemical investigations were analyzed from 1217 patients with suspected cardiac amyloidosis referred for evaluation in specialist centers. Of 857 patients with histologically proven amyloid (374 with endomyocardial biopsies) and 360 patients subsequently confirmed to have nonamyloid cardiomyopathies, myocardial radiotracer uptake on bone scintigraphy was >99% sensitive and 86% specific for cardiac ATTR amyloid, with false positives almost exclusively from uptake in patients with cardiac AL amyloidosis. Importantly, the combined findings of grade 2 or 3 myocardial radiotracer uptake on bone scintigraphy and the absence of a monoclonal protein in serum or urine had a specificity and positive predictive value for cardiac ATTR amyloidosis of 100% (positive predictive value confidence interval, 98.0-100). CONCLUSIONS: Bone scintigraphy enables the diagnosis of cardiac ATTR amyloidosis to be made reliably without the need for histology in patients who do not have a monoclonal gammopathy. We propose noninvasive diagnostic criteria for cardiac ATTR amyloidosis that are applicable to the majority of patients with this disease.