Skeletal muscle fat quantification by dual-energy computed tomography in comparison with 3T MR imaging

Abstract

Objectives To quantify the proportion of fat within the skeletal muscle as a measure of muscle quality using dual-energy CT (DECT) and to validate this methodology with MRI. Methods Twenty-one patients with abdominal contrast-enhanced DECT scans (100 kV/Sn 150 kV) underwent abdominal 3-T MRI. The fat fraction (DECT-FF), determined by material decomposition, and HU values on virtual non-contrast-enhanced (VNC) DECT images were measured in 126 regions of interest (≥ 6 cm2) within the posterior paraspinal muscle. For validation, the MR-based fat fraction (MR-FF) was assessed by chemical shift relaxometry. Patients were categorized into groups of high or low skeletal muscle mean radiation attenuation (SMRA) and classified as either sarcopenic or non-sarcopenic, according to the skeletal muscle index (SMI) and cut-off values from non-contrast-enhanced single-energy CT. Spearman’s and intraclass correlation, Bland-Altman analysis, and mixed linear models were employed. Results The correlation was excellent between DECT-FF and MR-FF (r = 0.91), DECT VNC HU and MR-FF (r = - 0.90), and DECT-FF and DECT VNC HU (r = − 0.98). Intraclass correlation between DECT-FF and MR-FF was good (r = 0.83 [95% CI 0.71–0.90]), with a mean difference of - 0.15% (SD 3.32 [95% CI 6.35 to − 6.66]). Categorization using the SMRA yielded an eightfold difference in DECT VNC HU values between both groups (5 HU [95% CI 23–11], 42 HU [95% CI 33–56], p = 0.05). No significant relationship between DECT-FF and SMI-based classifications was observed. Conclusions Fat quantification within the skeletal muscle using DECT is both feasible and reliable. DECT muscle analysis offers a new approach to determine muscle quality, which is important for the diagnosis and therapeutic monitoring of sarcopenia, as a comorbidity associated with poor clinical outcome. Key Points • Dual-energy CT (DECT) material decomposition and virtual non-contrast-enhanced DECT HU values assess muscle fat reliably. • Virtual non-contrast-enhanced dual-energy CT HU values allow to differentiate between high and low native skeletal muscle mean radiation attenuation in contrast-enhanced DECT scans. • Measuring muscle fat by dual-energy computed tomography is a new approach for the determination of muscle quality, an important parameter for the diagnostic confirmation of sarcopenia as a comorbidity associated with poor clinical outcome.

Fat Quantification in Dual-Layer Detector Spectral Computed Tomography

“…Compared with the first study from 2020, 13 the agreement for dlsCT and MRR in this study was slightly better ( r = 0.83 13 vs r = 0.96). Concerning the mean difference and 95% limits of agreement, the results for the skeletal muscle by dlsCT in this study (0.5% [95% CI, −4.3 to 5.3]) are comparable (and even identical) to the ranges published by both studies on dual-source CT (0.15% [95% CI, −6.66 to 6.35] 13 ; 0.5% [95% CI −4.3 to 5.3] 35 ).…”

“…Besides one study that described correlation of dual-source CT results to the morphological appearance of muscular fatty infiltration in the rotator cuff, 38 there are 2 studies that verified dual-source CT fat quantification by MRI, both with a focus on the paraspinal muscle. Compared with the first study from 2020, 13 the agreement for dlsCT and MRR in this study was slightly better ( r = 0.83 13 vs r = 0.96). Concerning the mean difference and 95% limits of agreement, the results for the skeletal muscle by dlsCT in this study (0.5% [95% CI, −4.3 to 5.3]) are comparable (and even identical) to the ranges published by both studies on dual-source CT (0.15% [95% CI, −6.66 to 6.35] 13 ; 0.5% [95% CI −4.3 to 5.3] 35 ).…”

“… 11 Furthermore, DECT fat quantification results that are not influenced by contrast agent are relevant to characterize lesions, for example, of the adrenal gland, 12 and have recently been proposed as a more reliable radiological measure of myosteatosis. 13 Myosteatosis is defined as fatty infiltration of the skeletal muscle and a parameter of muscle quality. 14 This is of clinical relevance as measuring muscle quality is necessary to confirm the diagnosis of sarcopenia.…”

Effects of liraglutide or lifestyle interventions combined with other antidiabetic drugs on abdominal fat distribution in people with obesity and type 2 diabetes mellitus evaluated by the energy spectrum ct: A prospective randomized controlled study

“…To evaluate the distribution of abdominal ectopic fat in patients with obesity and T2DM and study the body composition, DEXA and abdominal MRI methods were mostly used, but these methods cannot be widely used in clinical due to the high cost and long time required for examination (25). The energy spectrum CT quantification technology that appeared in recent years can perform density imaging of paired base substances through instantaneous high and low voltage switching, obtain the density ratio map of the paired base substances, use its attenuation change to analyze the content of base substances, and directly measure the content of abdominal visceral fat and intramuscular fat, and compared with MRI and DEXA, it has the advantages of shorter time consumption and lower radiation dose, which does not increase the X-ray radiation dose during the detection of fat content (5,26). In this study, energy spectrum CT was innovatively used to evaluate the changes in abdominal fat distribution in patients with obesity and T2DM after liraglutide administration and lifestyle interventions.…”

Prediction of abdominal CT body composition parameters by thoracic measurements as a new approach to detect sarcopenia in a COVID-19 cohort

“…If patients received several CT scans during their hospitalization, the first scan was used. Exclusion criteria were: (a) non-ICU patients to generate a more homogenous collective, and (b) non-contrast-enhanced examinations because the muscle radiodensity attenuation (MRA) would differ between contrast-enhanced and non-contrast-enhanced scans 22 , which biases comparability between patients if no dual-energy CT scans for contrast-agent independent muscle characterization are available 23 . Furthermore, patients were excluded if their CT scans showed (c) artifacts in the paravertebral muscle, e.g., due to osteosynthesis material, (d) did not include the whole abdominal muscle area, or (e) displayed an open abdomen, as all of this could hinder the determination of the skeletal muscle area (SMA) and MRA at L3.…”