MRI-based monitoring of prostate cancer after HIFU: Inter-reader agreement and diagnostic performance of the PI-FAB score.

PURPOSE: To investigate inter-reader agreement, and diagnostic performance of the Prostate Imaging after Focal Ablation (PI-FAB) score applied to multiparametric MRI (mpMRI) in patients who underwent focal high-intensity focused ultrasound (HIFU) therapy for localized prostate cancer. METHODS: In this retrospective, IRB-approved, single-center study, 73 men, who underwent focal HIFU treatment and received follow-up mpMRIs with subsequent prostate biopsies, were included. The PI-FAB score was applied to follow-up MRIs at 6, 12, and 36 months post-HIFU by two radiologists with different experience levels. Inter-reader agreement was assessed using Gwet's AC1, and the diagnostic performance of the PI-FAB score was assessed in relation to histopathologic results of subsequent prostate biopsies for each reader. RESULTS: PI-FAB scores showed substantial to almost perfect inter-reader agreement (AC1: 0.80-0.95) and demonstrated high specificity (Reader 1: 90-98 %, Reader 2: 87-98 %) and NPVs (Reader 1: 91-100 %, Reader 2: 88-97 %) in ruling out residual or recurrent in-field prostate cancer post-HIFU. Sensitivity (Reader 1: ≥43 %, Reader 2: ≥14 %) and PPVs (Reader 1: ≥33 %, Reader 2: ≥14 %) were mostly relatively lower, with notable disparities between the two readers, indicating the potential influence of radiologist experience. CONCLUSIONS: The PI-FAB score provides a consistent and reliable tool for post-HIFU monitoring of prostate cancer using mpMRI. It demonstrates substantial to almost perfect inter-reader agreement and is particularly effective in excluding in-field residual or recurrent prostate cancer post-HIFU treatment. Its application can potentially enhance post-treatment patient care, emphasizing its value as a non-invasive MRI-based monitoring approach after focal ablative therapy of the prostate.

MRI-Based Evaluation of the Flexor Digitorum Superficialis Anatomy: Investigating the Prevalence and Morphometry of the "Chiasma Antebrachii".

Recent dissection studies resulted in the introduction of the term "chiasma antebrachii", which represents an intersection of the flexor digitorum superficialis (FDS) tendons for digits 2 and 3 in the distal third of the forearm. This retrospective investigation aimed to provide an MRI-based morphologic analysis of the chiasma antebrachii. In 89 patients (41 women, 39.3 ± 21.3 years), MRI examinations of the forearm (2010-2021) were reviewed by two radiologists, who evaluated all studies for the presence and length of the chiasma as well as its distance from the distal radioulnar and elbow joint. The chiasma antebrachii was identified in the distal third of the forearm in 88 patients (98.9%), while one intersection was located more proximally in the middle part. The chiasma had a median length of 28 mm (interquartile range: 24-35 mm). Its distances to the distal radioulnar and elbow joint were 16 mm (8-25 mm) and 215 mm (187-227 mm), respectively. T1-weighted post-contrast sequences were found to be superior to T2- or proton-density-weighted sequences in 71 cases (79.8%). To conclude, the chiasma antebrachii is part of the standard FDS anatomy. Knowledge of its morphology is important, e.g., in targeted injections of therapeutics or reconstructive surgery.

Biogenesis and release of endothelial extracellular vesicles: Morphological aspects.

BACKGROUND: Cell-cell communication through extracellular vesicles (EVs) including exosomes, microvesicles and apoptotic bodies has been shown to be important in physiological homoeostasis as well as pathological processes such as atherosclerosis. However, while the cellular machinery controlling EV formation and composition has been studied during the past decade, less is known about the morphological process of their formation and release. METHODS: Using different electron microscopic approaches including transmission-, scanning-, immun-, and serial block face electron microscopy we studied the morphogenetic events of EV formation and release. We analysed the different steps of EV formation and release in cultured myocardial endothelial (MyEnd) and aortic endothelial (AoEnd) cell lines under serum starvation and under inflammatory conditions. RESULTS: We show that in a narrow time frame, the number of active cells and microvesicle (MV) producing cells increased in dependence of time spent in cultivation and additional stimulation by TNF-α. However, MV secretion was a highly heterogeneous process which couldn´t be seen in all cells cultivated under the same conditions. Release of MVs could be observed all over the cells' surface with no preferred release site. While no single specific microscopic approach applied was sufficient to provide a comprehensive analysis of EV biogenesis, we show that the limitations of one technique could be compensated by the qualities of the respective other applied techniques, thus enabling us to provide a detailed ultrastructural analysis of MV and exosome biogenesis. Surprisingly, exosome release in endothelial cells occurred via a yet undescribed process indicating that MVBs were incorporated into a novel distinct cellular compartment covered by fenestrated endothelium before exosome release. Lastly, we could show that TNF-α stimulation of AoEnd cells leads not only to the upregulation of CD44 in parental cells, but also to incorporation of CD44 into the membranes of generated MVs and exosomes. CONCLUSIONS: Taken together, our data contribute to a better understanding of biogenesis and release of EVs. We conclude that under inflammatory conditions, EVs can mediate the transfer of CD44 from endothelial cells to target cells at distant sites including vessel wall cells and this could be a mechanism by which MVs may change the and thus contribute to the development and progression of atherosclerotic lesions.