Reliability of Skeletal Muscle Area Measurement on CT with Different Parameters: A Phantom Study

ObjectiveTo evaluate the reliability of CT measurements of muscle quantity and quality using variable CT parameters.Materials and MethodsA phantom, simulating the L2–4 vertebral levels, was used for this study. CT images were repeatedly acquired with modulation of tube voltage, tube current, slice thickness, and the image reconstruction algorithm. Reference standard muscle compartments were obtained from the reference maps of the phantom. Cross-sectional area based on the Hounsfield unit (HU) thresholds of muscle and its components, and the mean density of the reference standard muscle compartment, were used to measure the muscle quantity and quality using different CT protocols. Signal-to-noise ratios (SNRs) were calculated in the images acquired with different settings.ResultsThe skeletal muscle area (threshold, −29 to 150 HU) was constant, regardless of the protocol, occupying at least 91.7% of the reference standard muscle compartment. Conversely, normal attenuation muscle area (30–150 HU) was not constant in the different protocols, varying between 59.7% and 81.7% of the reference standard muscle compartment. The mean density was lower than the target density stated by the manufacturer (45 HU) in all cases (range, 39.0–44.9 HU). The SNR decreased with low tube voltage, low tube current, and in sections with thin slices, whereas it increased when the iterative reconstruction algorithm was used.ConclusionMeasurement of muscle quantity using HU threshold was reliable, regardless of the CT protocol used. Conversely, the measurement of muscle quality using the mean density and narrow HU thresholds were inconsistent and inaccurate across different CT protocols. Therefore, further studies are warranted in future to determine the optimal CT protocols for reliable measurements of muscle quality.     

Impact of age on coronary artery plaque progression and clinical outcome: A PARADIGM substudy

BackgroundThe association of age with coronary plaque dynamics is not well characterized by coronary computed tomography angiography (CCTA).MethodsFrom a multinational registry of patients who underwent serial CCTA, 1153 subjects (61 ± 5 years old, 61.1% male) were analyzed. Annualized volume changes of total, fibrous, fibrofatty, necrotic core, and dense calcification plaque components of the whole heart were compared by age quartile groups. Clinical events, a composite of all-cause death, acute coronary syndrome, and any revascularization after 30 days of the initial CCTA, were also analyzed. Random forest analysis was used to define the relative importance of age on plaque progression.ResultsWith a 3.3-years’ median interval between the two CCTA, the median annual volume changes of total plaque in each age quartile group was 7.8, 10.5, 10.8, and 12.1 mm³/year and for dense calcification, 2.5, 4.6, 5.4, and 7.1 mm³/year, both of which demonstrated a tendency to increase by age (p-for-trend = 0.001 and < 0.001, respectively). However, this tendency was not observed in any other plaque components. The annual volume changes of total plaque and dense calcification were also significantly different in the propensity score-matched lowest age quartile group versus the other age groups as was the composite clinical event (log-rank p = 0.003). In random forest analysis, age had comparable importance in the total plaque volume progression as other traditional factors.ConclusionsThe rate of whole-heart plaque progression and dense calcification increases depending on age. Age is a significant factor in plaque growth, the importance of which is comparable to other traditional risk factors.Clinical trial registrationURL: http://www.clinicaltrials.gov. Unique identifiers: NCT02803411.     

Torsional Resistance of WaveOne Gold and Reciproc Blue according to the Loading Methods

IntroductionThis study aimed to compare the torsional resistances and fracture modes of WaveOne Gold (Dentsply Sirona, Ballaigues, Switzerland) and Reciproc Blue (VDW, Munich, Germany) using the repetitive torsional loading (RTL) method and the conventional single-rotation (STL) method.MethodsA 3-mm file tip was fixed with a brass plate, and a torsional load was applied using a custom device. In the RTL method, the file was driven counterclockwise at 50 rpm until it achieved the preset torque of 0.5 Ncm; thereafter, it was returned to its original position. This recovery of the file to its original position was defined as 1 torsional loading cycle; the number of repetitive load cycles until fracture was counted. In the STL method, the files were rotated at a constant rate of 2 rpm in a counterclockwise direction until file fracture. The fragments fractured by the 2 methods were compared under a scanning electron microscope to examine the topographic features of the fractured surfaces and longitudinal aspects.ResultsWith the RTL method, Reciproc Blue showed a higher number of repetitive load cycles until fracture than WaveOne Gold (P < .05). With the STL method, Reciproc Blue also had a higher ultimate strength than WaveOne Gold (P < .05). Scanning electron microscopic findings of the fractured specimens from the 2 test methods showed different features of torsional failure.ConclusionsWithin the study limitations, both the RTL and STL methods conferred similar torsional resistance. Therefore, the clinically relevant RTL method with repetitive and reciprocation motion can be used for testing torsional resistance.     

Association of Carotid Intraplaque Hemorrhage and Territorial Acute Infarction in Patients with Acute Neurological Symptoms Using Carotid Magnetization-Prepared Rapid Acquisition with Gradient-Echo

Objective

The purpose of our study was to assess prevalence of carotid intraplaque hemorrhage (IPH) and associations between territorial acute infarction and IPH on magnetization-prepared rapid acquisition with gradient-echo (MPRAGE) in patients with acute neurologic symptoms.

Methods

83 patients with suspected acute neurologic symptoms were evaluated with both brain diffusion weighted imaging (DWI) and carotid MPRAGE sequences. Carotid plaque with high signal intensity on MPRAGE of >200% that of adjacent muscle was categorized as IPH. We analyzed the prevalence of IPH and its correlation with territorial acute infarction.

Results

Of 166 arteries, 39 had a carotid artery plaque. Of these arteries, 26 had carotid artery stenosis less than 50%. In all carotid arteries, MR-depicted IPH was found in 7.2% (12/166). High-signal intensity on DWI was found in 17.5% (29/166). Combined lesion with ipsilateral high-signal intensity on DWI and IPH on carotid MPRAGE sequence was found in 6 lesions (6/166, 3.6%). Of patients with carotid artery plaque, MR-predicted IPH was found in 30.8% (12/39) and match lesions with high-signal intensity on DWI and MPRAGE was found in 15.4% (6/39). MR-predicted IPH was significantly higher prevalence in high-grade stenosis group (p=0.010). Relative risk between carotid MPRAGE-positive signal and ipsilateral high-signal intensity on DWI in arteries with carotid artery plaques was 6.8 (p=0.010).

Conclusion

Carotid MPRAGE-positive signal in patients was associated with an increased risk of territorial acute infarction as detected objectively by brain DWI. The relative risk of stroke was increased in high-grade stenosis categories.     

Effect of a muscle strengthening exercise program for pelvic control on gait function of stroke patients

[Purpose] The purpose of this study was to investigate the effects of strengthening exercises for the hip extensors on the gait performance and stability of patients with hemiplegia. [Subjects and Methods] The subjects were fifteen stroke patients (ten males, five females). The experimental subjects performed a hip extensor strengthening exercise (HESE) program for a total of four weeks. [Results] The experimental subjects showed significant improvements after the HESE program. Especially, walking speed and the affected side stance phase time significantly increased after the HESE program. Furthermore, the affected side stride length and symmetry index in the stance phase significantly increased after HESE program. [Conclusion] These results suggest that the HESE program may, in part, help to improve gait performance ability and stabilize physical disability after stroke.Key words: Stroke patients, Hip extensor strengthening exercise (HESE) program, Gait function