Quantitative analysis of dynamic contrast enhanced medical images with tracer kinetics models for In Vivo assessment of tumor physiology

Objectives: To characterize adventitial vasa vasorum (VV) in unilaterally symptomatic patients and evaluate its association with intraplaque hemorrhage (IPH) and symptom status. Background: Adventitial VV is thought to be a primary source of IPH and a potential marker for plaque instability. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has been shown capable of quantifying adventitial VV in the carotid artery. Methods: Patients with ischemic cerebrovascular symptoms within the past 6 months and ipsilateral carotid plaques underwent MR imaging examination, which included a multi-contrast protocol for detecting IPH and a DCE-MRI protocol for measuring adventitial VV. Both the symptomatic and contralateral asymptomatic arteries were studied. Adventitial VV was measured at consecutive slices as adventitial Ktrans from kinetic modeling. Maximum adventitial Ktrans across all slices were calculated for each artery. Results: From the 27 patients (22 men; 69±10 years) recruited, 50 arteries had adventitial Ktrans measurements. IPH arteries (0.142±0.042 vs. 0.112±0.029 min-1, p<0.001) and symptomatic arteries (0.134±0.038 vs. 0.107±0.027 min-1, p=0.001) were shown to have higher adventitial Ktrans compared to their counterparts. In multivariate analysis, IPH, symptom status and male sex were independently associated with adventitial Ktrans. Conclusions: Adventitial VV demonstrated significant associations with IPH and symptom status. In vivo assessment of adventitial VV by DCE-MRI may be useful in studying plaque pathogenesis or risk stratification, but further examination through prospective studies is needed.

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Dynamic contrast-enhanced magnetic resonance imaging for monitoring neovascularization during bone regeneration—a randomized in vivo study in rabbits

Clinical Oral Investigations ◽

10.1007/s00784-021-03889-6 ◽

2021 ◽

Author(s):

L. A. R. Righesso ◽

M. Terekhov ◽

H. Götz ◽

M. Ackermann ◽

T. Emrich ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Bone Regeneration ◽

Blood Perfusion ◽

Autogenous Bone ◽

Resonance Imaging ◽

Dce Mri ◽

Dynamic Contrast Enhanced ◽

Contrast Enhanced

Abstract Objectives Micro-computed tomography (μ-CT) and histology, the current gold standard methods for assessing the formation of new bone and blood vessels, are invasive and/or destructive. With that in mind, a more conservative tool, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), was tested for its accuracy and reproducibility in monitoring neovascularization during bone regeneration. Additionally, the suitability of blood perfusion as a surrogate of the efficacy of osteoplastic materials was evaluated. Materials and methods Sixteen rabbits were used and equally divided into four groups, according to the time of euthanasia (2, 3, 4, and 6 weeks after surgery). The animals were submitted to two 8-mm craniotomies that were filled with blood or autogenous bone. Neovascularization was assessed in vivo through DCE-MRI, and bone regeneration, ex vivo, through μ-CT and histology. Results The defects could be consistently identified, and their blood perfusion measured through DCE-MRI, there being statistically significant differences within the blood clot group between 3 and 6 weeks (p = 0.029), and between the former and autogenous bone at six weeks (p = 0.017). Nonetheless, no significant correlations between DCE-MRI findings on neovascularization and μ-CT (r =−0.101, 95% CI [−0.445; 0.268]) or histology (r = 0.305, 95% CI [−0.133; 0.644]) findings on bone regeneration were observed. Conclusions These results support the hypothesis that DCE-MRI can be used to monitor neovascularization but contradict the premise that it could predict bone regeneration as well.

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