Prognostic Value of 99mTc-HMDP Scintigraphy in Elderly Patients With Chronic Heart Failure.

BACKGROUND: This study evaluated the prevalence and prognostic significance of cardiac transthyretin amyloidosis (ATTR) diagnosed using 99mTc- hydroxymethylene-diphosphonate (99mTc-HMDP) scintigraphy in an elderly heart failure population. METHODS: This retrospective study included 335 patients aged >70 years with heart failure and who underwent 99mTc-HMDP scintigraphy due to non-cardiac reasons in three imaging centres in Finland (Kymenlaakso Central Hospital, Jorvi Central Hospital, and Meilahti University Hospital). A Perugini grade >2 and heart-to-contralateral ratio (H/CL) of ≥1.30 were considered positive for cardiac ATTR. The overall and cardiovascular mortality were obtained from the national statistical service (Statistics Finland). RESULTS: There were 234 deaths, of which 70 were classified as being due to cardiovascular causes during a median follow-up of 1 (1-3) year. Transthyretin amyloidosis was diagnosed in 22 patients (6.6%) using visual analysis and 17 patients using the H/CL ratio (5.1%). Patients with ATTR were older (85±5 vs 80±5 yrs; p=0.002) and had higher N-terminal pro-brain natriuretic peptide (NT-ProBNP) levels (1,451 [813-3,799] vs 6,192 [2,030-8,833] ng/L; p=0.02). Age, bone metastases, and glomerular filtration rate were independent predictors of overall mortality in multivariable analysis. Age, glomerular filtration rate, ≥grade 2 visual cardiac uptake, and H/CL ratio were independent predictors of cardiovascular mortality. CONCLUSIONS: Cardiac uptake suggestive of ATTR was found in 5% of elderly patients with chronic heart failure. The presence of cardiac uptake on bone scintigraphy did not convey independent prognostic value on overall mortality but was independently associated with cardiovascular mortality.

Estimation of additional dosimetry from low-dose CT scan to 99mTc-HMDP SPECT/CT.

INTRODUCTION: Currently, the addition of computed tomography (CT) to a gamma-camera has revolutionized nuclear medicine. Indeed the CT, because of its good spatial resolution, of the attenuation correction of the single photon emission computed tomography (SPECT) images and of a better anatomical localization of lesions, improves the sensitivity, specificity and accuracy of the examination. Despite the fact that the hybrid camera uses a low-dose non-diagnostic scanner, increases the overall delivered dose of radiation. METHODS: The aim of this study was to evaluate the contribution of CT to the total effective dose of 99mTc-HMDP (hydroxymethylenediphosphonate labelled with technetium 99 metastable) SPECT/CT for an adult oncologic population. This prospective study included 103 patients (75 women and 28 men) aged 28 to 79 years. RESULTS: The mean effective doses of SPECT, CT and SPECT/CT were respectively 3.8 mSv, 3.3 mSv and 7.1 mSv, respectively. The average contribution of CT scans to the total effective dose for SPECT/CT examination was 45 ± 9.7%, and ranged from 10 to 67.4%. The lowest value was for the thorax area. CONCLUSION: This radiation dose is not negligible. But, taking into account the benefit of hybrid imaging, this additional radiation remains justifiable. Nevertheless, the "As Low as Reasonably Achievable (ALARA)'' principle must be respected to ensure that the patient is not subjected to unnecessarily high levels of radiation.

Cardiac Scintigraphy With Technetium-99m-Labeled Bone-Seeking Tracers for Suspected Amyloidosis: JACC Review Topic of the Week.

Technetium-labeled cardiac scintigraphy (i.e., Tc-PYP scan) has been repurposed for the diagnosis of transthyretin amyloid cardiomyopathy (ATTR-CM). Validated in cohorts of patients with heart failure and echocardiographic and/or cardiac magnetic resonance imaging findings suggestive of cardiac amyloidosis, cardiac scintigraphy can confirm the diagnosis of ATTR-CM only when combined with blood and urine testing to exclude a monoclonal protein. Multisocietal guidelines support the nonbiopsy diagnosis of ATTR-CM using cardiac scintigraphy, yet emphasize its use in the appropriate clinical context and the crucial need to rule out light chain amyloid cardiomyopathy. Although increased awareness of ATTR-CM and the advent of effective therapy have led to rapid adoption of diagnostic scintigraphy, there is heterogeneity in adherence to consensus guidelines. This perspective outlines clinical scenarios wherein findings on technetium-labeled cardiac scintigraphy have been misinterpreted, reviews causes of false-negative and false-positive results, and provides strategies to avoid costly and potentially fatal misdiagnoses.