Page 223 - EJMO-9-1

Eurasian Journal of Medicine and
Oncology
Psoas muscle and atherosclerotic inflammation

the formation of atherosclerotic plaques, a process that choice in atherosclerosis settings. 20,21 Nonetheless, different
develops over time through the accumulation of vascular quantification indices for FDG uptake may result in
smooth muscle cells and an abundance of inflammatory inconsistent findings. Therefore, the main objective of
22
cells, including active macrophages. Active macrophages the current study is to conduct a preliminary evaluation
have been shown to play a significant role in the of the association between atherosclerotic inflammation
formation and progression of atherosclerotic plaques. and arterial calcification, using the arterial tissue-to-psoas
3
In addition, fat is a key component in atherosclerotic muscle ratio (TMR) as a novel approach for quantifying
plaques, where it undergoes oxidation to form oxidized FDG uptake.
lipids within the arterial wall. Atherosclerotic plaque
4
can develop suddenly, regardless of age, and may begin 2. Materials and methods
in childhood, with a mean age of onset ranging from 5 to Thirteen atherosclerotic patients (six males and seven
15 years. Furthermore, the presence of atherosclerotic females), aged between 65 and 77 years, with a mean
5,6
plaques can occur without any known cause. As a result, weight of 67.30 ± 13.40 kg, were scanned using FDG-
7
establishing a standardized model for the early detection PET/CT. PET/CT acquisitions were carried out on
or stability assessment of atherosclerotic plaques remains a Philips Gemini TF 16 PET/CT (Philips Medical
challenging. 8 Systems, the Netherlands), which is equipped with
One well-known characteristic of plaque status is time-of-flight capability. All patients fasted for at
the calcium burden within the arterial wall. However, least 6 h before the scan, and their blood sugar levels
the pathological significance of calcium burden in were ensured to be under 180 mg/dL to minimize the
atherosclerotic plaques remains unclear. Calcium burden potential underestimation of FDG uptake caused by
23
has been either disregarded in clinical considerations, elevated blood sugar levels. The average blood sugar
9
identified as a marker of stable atherosclerotic plaques, level assessed just before FDG administration was
10
or seen as an actively regulated process associated with 87.4 ± 12.4 mg/dL (mean ± standard deviation). An
inflammation, indicating unstable plaques. 12 average dose of FDG (201.80 ± 40.235 Mega-Becquerel
11
“MBq”) was administrated intravenously and adjusted
Unstable atherosclerotic plaques are a major cause according to the patient’s weight. PET images were
of severe CVD complications, including cardiovascular acquired in continuous mode from the time of injection
morbidity and mortality. Recent studies have reported a up to 33 min post-injection. The descending aorta,
strong association between calcium burden in the arterial femoral, and iliac arteries were automatically delineated
wall and the severity of atherosclerotic burden (unstable on the first ten frames of the continuous PET images
atherosclerotic plaque), which contributes to serious (two minutes total, averaging 10 s/frame). These frames
complications. 13 were collected immediately after FDG injection, during
Medical imaging plays a vital role in the detection which FDG activity is primarily present in the blood,
of atherosclerosis and the assessment of its major allowing for automatic delineation of the arteries,
events. One such feature is luminal stenosis, which can assisted by an active contours model. The arterial
be determined using anatomical imaging modalities. delineations in the PET images were co-registered with
However, luminal stenosis alone is not the sole factor the corresponding slices of CT images (using location
leading to atherosclerosis complications; inflammation data from the DICOM header information), and the
plays a critical role in the progression of the disease. arteries were quasi-automatically segmented in the CT
14
In addition, the calcium burden exacerbates the images. Arterial calcification was identified through
development of advanced atherosclerosis. Therefore, thresholding applied to the arterial segments (regions
15
positron emission tomography-computed tomography of interest [ROIs]), following the Agatston approach
(PET-CT) offers a highly sensitive imaging modality that for determining the pixel attenuation value indicative
provides both qualitative and quantitative assessments of calcium in the CT images. A conventional threshold
of atherosclerotic disease, from calcium burden to of 130 CT numbers and a minimum calcium size of 2
inflammation levels. 16 pixels connected horizontally or vertically, were used
Fluorodeoxyglucose (FDG) signal has shown to to identify arterial calcification. The calcium level was
24
be associated with various cardiovascular risk factors then classified into four clusters. The classification
and inflammatory states, due to its high affinity for of calcium levels for all arterial segments is detailed in
macrophage-rich atherosclerotic plaques. 17-19 In addition, Table 1.
lipid-lowering therapies influence FDG uptake, further The calcium area in CT images was estimated for each
supporting its utilization as a radiopharmaceutical of arterial segment (ROI) and normalized to the arterial wall

Volume 9 Issue 1 (2025) 215 doi: 10.36922/ejmo.7727