Comparison of quantitative whole body PET parameters on [68Ga]Ga-PSMA-11 PET/CT using ordered Subset Expectation Maximization (OSEM) vs. bayesian penalized likelihood (BPL) reconstruction algorithms in men with metastatic castration-resistant prostate cancer.

BACKGROUND: PSMA PET/CT is a predictive and prognostic biomarker for determining response to [177Lu]Lu-PSMA-617 in patients with metastatic castration resistant prostate cancer (mCRPC). Thresholds defined to date may not be generalizable to newer image reconstruction algorithms. Bayesian penalized likelihood (BPL) reconstruction algorithm is a novel reconstruction algorithm that may improve contrast whilst preventing introduction of image noise. The aim of this study is to compare the quantitative parameters obtained using BPL and the Ordered Subset Expectation Maximization (OSEM) reconstruction algorithms. METHODS: Fifty consecutive patients with mCRPC who underwent [68Ga]Ga-PSMA-11 PET/CT using OSEM reconstruction to assess suitability for [177Lu]Lu-PSMA-617 therapy were selected. BPL algorithm was then used retrospectively to reconstruct the same PET raw data. Quantitative and volumetric measurements such as tumour standardised uptake value (SUV)max, SUVmean and Molecular Tumour Volume (MTV-PSMA) were calculated on both reconstruction methods. Results were compared (Bland-Altman, Pearson correlation coefficient) including subgroups with low and high-volume disease burdens (MTV-PSMA cut-off 40 mL). RESULTS: The SUVmax and SUVmean were higher, and MTV-PSMA was lower in the BPL reconstructed images compared to the OSEM group, with a mean difference of 8.4 (17.5%), 0.7 (8.2%) and - 21.5 mL (-3.4%), respectively. There was a strong correlation between the calculated SUVmax, SUVmean, and MTV-PSMA values in the OSEM and BPL reconstructed images (Pearson r values of 0.98, 0.99, and 1.0, respectively). No patients were reclassified from low to high volume disease or vice versa when switching from OSEM to BPL reconstruction. CONCLUSIONS: [68Ga]Ga-PSMA-11 PET/CT quantitative and volumetric parameters produced by BPL and OSEM reconstruction methods are strongly correlated. Differences are proportional and small for SUVmean, which is used as a predictive biomarker. Our study suggests that both reconstruction methods are acceptable without clinical impact on quantitative or volumetric findings. For longitudinal comparison, committing to the same reconstruction method would be preferred to ensure consistency.

Cervical Lymph Node Metastasis From Recurrent Glioblastoma Detected by MRI and 2-[18F]FDG PET/CT.

ABSTRACT: A 53-year-old man diagnosed with recurrent glioblastoma after multimodal treatment on a follow-up brain MRI. Because of a palpable mass in the neck, the patient underwent a whole-body 2-[18F]FDG PET/CT, which revealed hypermetabolic laterocervical confluent lymphadenopathies. A nodal cervical biopsy indicated distant metastases from glioblastoma. Recent studies have confirmed dural meningeal lymphatics, as part of the glymphatic system, which provide clearance of interstitial solutes from the brain parenchyma into cervical lymphatics. Nodal cervical metastases from glioblastoma, using this pathway, are extremely rare and have been almost unthinkable some years ago.

Papel actual de las técnicas de imagen en la amiloidosis cardíaca / Current role of imaging techniques in cardiac amyloidosis

La amiloidosis cardíaca (AC) es una enfermedad infradiagnosticada, y si no se trata es rápidamente fatal. Los nuevos tratamientos disponibles aumentan la necesidad de desarrollar métodos diagnósticos no invasivos para su detección precoz y para la monitorización de la respuesta terapéutica. Los hallazgos típicos de la AC en ecocardiografía y resonancia magnética, no son suficientemente específicos para distinguir la AC de cadenas ligeras (AL) de la amiloidosis por transtiretina (ATTR). La captación de un radiofármaco óseo por el miocardio es altamente específica para la AC-ATTR cuando se ha excluido la discrasia de células plasmáticas. Ahora, este método diagnóstico está reemplazando la necesidad de biopsia en muchos pacientes. La detección precoz de la AC, la cuantificación de su carga y la evaluación de la respuesta al tratamiento son los siguientes pasos importantes para que las imágenes avancen en la evaluación y el tratamiento de la AC. (AU)

Cardiac amyloidosis (CA) is an underdiagnosed disease and, if left untreated, rapidly fatal. Emerging therapies for CA increase the urgency of developing non-invasive diagnostic methods for its early detection and for monitoring therapeutic response. Classic imaging features on echocardiography and cardiac magnetic resonance, although typical for cardiac amyloidosis, are not specific enough to distinguish light chain amyloidosis from transthyretin. Myocardial bone-avid radiotracer uptake is highly specific for transthyretin cardiac amyloidosis when plasma cell dyscrasia has been excluded; it is now replacing the need for biopsy in many patients. Detection of early cardiac amyloidosis, quantitation of its burden, and assessment of response to therapy are important next steps for imaging to advance the evaluation and management of cardiac amyloidosis. (AU)

[Current role of imaging techniques in cardiac amyloidosis]. / Papel actual de las técnicas de imagen en la amiloidosis cardíaca.

Cardiac amyloidosis (CA) is an underdiagnosed disease and, if left untreated, rapidly fatal. Emerging therapies for CA increase the urgency of developing non-invasive diagnostic methods for its early detection and for monitoring therapeutic response. Classic imaging features on echocardiography and cardiac magnetic resonance, although typical for cardiac amyloidosis, are not specific enough to distinguish light chain amyloidosis from transthyretin. Myocardial bone-avid radiotracer uptake is highly specific for transthyretin cardiac amyloidosis when plasma cell dyscrasia has been excluded; it is now replacing the need for biopsy in many patients. Detection of early cardiac amyloidosis, quantitation of its burden, and assessment of response to therapy are important next steps for imaging to advance the evaluation and management of cardiac amyloidosis.