Description of a different quantification method for amyloid burden (DPDload) and validation of SPECT/CT in cardiac amyloidosis.

BACKGROUND: Bone tracers such as 99mTc-DPD have shown high sensitivity and specificity in the non-invasive diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). This study aims to validate SPECT/CT and assess the usefulness of uptake quantification (DPDload) in the myocardial tissue as potential information on the amyloid burden. METHODS: In a retrospective analysis of 46 patients with suspected CA, 23 cases with ATTR-CA had two quantification methods conducted to estimate amyloid burden (DPDload) through planar scintigraphic scans and a SPECT/CT. RESULTS: SPECT/CT significantly provided an added value in the patient's diagnosis with CA (P<.05). The estimation of the amyloid burden substantiated that the most affected wall of the LV is the interventricular septum in most cases and the existence of a significant relationship between the Perugini score uptake and the DPDload. CONCLUSIONS: We validate the need for SPECT/CT to complement planar imaging in diagnosing ATTR-CA. For its part, quantifying the amyloid load continues to be a complex area of research. It requires further studies with a larger number of patients to validate a standardized method of amyloid load quantification, both for diagnosis and treatment monitoring.

Enhanced quantitative method for the diagnosis of grade 1 cardiac amyloidosis in 99mTc-DPD scintigraphy.

The lack of a standardized cut-off value in the quantitative method and an inter-observer disagreement in the evaluation of the semiquantitative score in 99mTc-DPD scintigraphy leaves several patients with cardiac amyloidosis (CA) undiagnosed (grade 1 and H/CL: 1-1.49). This study aims to increase diagnostic productivity of 99mTc-DPD scintigraphy in CA. This is a retrospective study of 170 patients with suspicion of CA. A total of 81 (47.6%) were classified as transthyretin CA (TTR-CA) and 9 (5.3%) as light-chain CA (LC-CA) applying the visual score. An enhanced quantitative method and cut-off point were attempted to reclassify inconclusive patients and reduce inter-observer variability. Applying the proposed quantitative method, of the 19 patients with grade 1 uptake, 2 became grade 0 (none-CA), 2 were reclassified as grade 3 (TTR-CA), and 2 were regrouped as grade 2 (1 TTR-CA and 1 LC-CA). Adjusting the quantitative method's cut-off value to 1.3, four patients previously inconclusive were reclassified as TTR-CA, the diagnosis was confirmed in 3 and rejected in 1. When a 1.3 threshold is compared to 1.5, the sensitivity increases to 94% without reducing its specificity. The quantitative method improves the visual interpretation, reclassifying doubtful cases. The optimization of the cut-off value from 1.5 to 1.3 reclassifies a higher percentage of patients as TTR-CA with a higher sensitivity without reducing its specificity.

Added-value of molecular imaging in myocardial metastasis of an ileal neuroendocrine tumour treated with peptide receptor radionuclide therapy: a case report.

BACKGROUND: Neuroendocrine tumours (NET) conform a rare type of neoplasm, mostly located in the gastrointestinal tract. They are slow-growing tumours, so at the time of the diagnosis, most patients present with metastatic lesions, mainly in the liver. The myocardium is a rare and important organ for metastasis, in which 68Ga-Dotatate positron emission tomography-computed tomography (PET/CT) shows a high diagnostic sensitivity for its detection, contrary to carcinoid valve disease, where anatomic imaging plays a key role, especially the echocardiogram. CASE SUMMARY: A 60-year-old man diagnosed with metastatic progressive ileal NET, who underwent a 68Ga-Dotatate PET/CT prior 177Lu-Dotatate therapy, showed a metastatic lesion in the left ventricle that was undetected in previous studies, such as an Octreoscan® and CT. A transthoracic echocardiogram was performed revealing the existence of a second cardiac lesion, a tricuspid valve carcinoid disease. A cardiac magnetic resonance showed no late gadolinium enhancement. DISCUSSION: The 68Ga-Dotatate PET/CT is currently considered the gold standard for assessment and follow-up of NET, including those with rare sites of metastasis such as cardiac infiltration. In this case, it stimulated the persue of possible cardiac involvement, detecting the coexistence of two types of lesions (cardiac metastasis and carcinoid valve disease). Of these, carcinoid valvulopathy develops in 50% of NET cases, while cardiac metastasis (CM) is less frequent (only 5%).