Equivocal vs Positive Technetium-99m-Pyrophosphate Scintigraphy for Transthyretin Amyloid Cardiomyopathy: Comparing Outcomes, Demographics, and Imaging
Bibliographic record
Abstract
Background: Transthyretin cardiac amyloidosis (ATTR-CM) is an underdiagnosed infiltrative cardiomyopathy. Diagnosis is based on Technetium-99m-pyrophosphate-bone-scintigraphy scans (Tc-99m-PYP) with grades 2 to 3 classified as positive. The clinical significance of grade 1 (classified equivocal by American Society of Nuclear Cardiology) is unclear. We aimed to describe the differences in clinical/imaging characteristics among those with equivocal vs positive Tc-99m-PYP and to describe outcomes of further investigations. Methods: We performed a retrospective study of patients who underwent Tc-99m-PYP at 2 institutions between January 2017 and November 2022. Baseline demographics, laboratory, and imaging data were collected. Results: A total of 502 Tc-99m-PYP were performed with single-photon emission computed tomography (SPECT) 3 hours post-tracer injection: 347 (69%) negative, 46 (9%) equivocal, and 109 (22%) positive. In the latter 2 groups, the median age was 78 (interquartile range [IQR]: 72-84) years, and 38 (25%) were female. Average follow-up was 19.7 ± 14.6 months. No patients with equivocal scans were diagnosed with ATTR-CM. Equivocal scans had lower intraventricular septal diameters (11 mm [IQR: 10-11] vs 15 mm [IQR: 12-17]), larger left ventricular end-diastolic dimension (50 mm [IQR: 44-56] vs 43 mm [IQR: 40-50]), and more negative global longitudinal strain (-18.7 [IQR: -22.2 to -18.7] vs -13.8 [IQR: -17.9 to -10.9] %). Only 12 (26%) patients with equivocal scans underwent further imaging or biopsy. Of 2 patients with monoclonal gammopathy, 1 had AL-amyloidosis. Conclusions: Our patients with equivocal grade 1 scans were not diagnosed with ATTR-CM. They exhibited distinct imaging compared to positive scans. Our findings suggest that ATTR-CM phenotype and equivocal scans may represent early ATTR-CM (ie, false negative) or false positives and should undergo further workup. Further research is needed to determine the significance of equivocal studies.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".