How reproducible are classical and new CT-pelvimetry measurements?

PurposeThe objective of this study was to assess the reliability and reproducibility of existing and new computed tomography (CT)-pelvimetry measurements.Material and methodsA retrospective cohort study of 63 women with a mean age of 33.9 ± 5.2 (SD) years (range: 19–49 years) was conducted. Classical pelvimetry measurements were collected including the obstetric conjugate (OC), median transverse diameter (MTD), and interspinous diameter (ISD). Additionally, we used multiplanar reconstruction (MPR) mode to define two oblique planes: inlet pelvic plane (IPP) and mid-pelvic plane (MPP) and measure new pelvic parameters, including anteroposterior (APD), transverse diameters and circumference of both IPP and MPP (inletAPD, inletMTD, inletCIRC and midAPD, ISD, midCIRC, respectively). The reproducibility (intra- and inter-observer) of our results were assessed. Multivariate analyses using principal component analysis and clustering methods were conducted to analyze the association between pelvimetry measurements and identify patient sub-groups.ResultsAll linear measurements (OC, inletAPD, MTD, inletMTD, midAPD, and ISD) showed statistically “almost perfect” intra- and inter-observer correlation coefficients (range: 0.924–0.980). Circumferences (inletCIRC and midCIRC) showed statistically “almost perfect” intra- (range: 0.847–0.857) and inter-observer correlation coefficients (range: 0.923–0.957). The measurement of 6 pelvimetric parameters allowed determining three groups of pelvis size.ConclusionNew pelvic measurements have excellent reproducibility and are similar to the classical measurements, based on the MPR analysis of CT planes adjusted to the inner bony pelvis.     

Impact of ultra-low dose CT acquisition on semi-automated RECIST tool in the evaluation of malignant focal liver lesions

PurposeTo compare the evaluation of malignant focal liver lesions (FLLs) using a semi-automated RECIST tool with a standard and an ultra-low dose (ULD) computed tomography (CT) protocol.Materials and methodsThirty-four patients with malignant FLLs underwent two abdominal-pelvic CT examinations one using a standard protocol and one using an ULD protocol. There were 23 men and 11 women with a mean age 64.3 ± 14.4 (SD) years (range: 22–91 years). Dosimetric indicators were recorded, and effective dose was calculated for both examinations. Mean malignant FLL attenuation, image noise and contrast-to-noise-ratio (CNR) were compared. The largest malignant FLL per patient was evaluated using the semi-automated RECIST tool to determine longest axis length, longest orthogonal axis length, volume and World Health Organisation area.ResultsDosimetric values were significantly reduced by −56% with ULD compared to standard protocol. No differences in mean malignant FLL attenuation values were found between the two protocols. Image noise was significantly increased for all locations (P < 0.05) with ULD compared to standard protocol, and CNR was significantly reduced (P < 0.05). On the 34 malignant FLLs analyzed, six semi-automated shapes non-concordant with radiologist's visual impression were highlighted with the software, including one FLL (1/34; 3%) with standard CT acquisition only, three FLLs (3/34; 9%) with ULD CT acquisition only and two FLLs (2/34; 6%) with both CT acquisitions. After manual editing, the concordance of the values of the studied criteria between both acquisitions was good and no significant difference was reported.ConclusionSemi-automated RECIST tool demonstrates good performances using ULD CT protocol. It could be used in routine clinical practice with a ULD protocol for follow-up studies in patients with known malignant FLL.     

Elastic Characteristics of Digital Cores from Longmaxi Shale Using Lattice Spring Models

Effective medium methods for the attribution of micro-structures to macro elastic properties of shales are important for the prediction of sweet spots in the shale-gas production. With X-ray micro-computed tomography (XMCT), the micro-structures of shale core samples from Longmaxi Formation are visualized and characterized by 3D digital images. As an efficient alternative to conventional effective medium methods for estimating elastic properties, we propose a consistent workflow of lattice spring modeling (LSM) to emulate the digital cores using three types of lattices. Particular attention is paid to investigate the effective Young's moduli, Poisson's ratios, and preferred orientations, by uniaxial compression tests along two directions. Within elastic deformation, the impact of lattice arrangements on the anisotropy is even more than those of stress disturbances and micro-structural features. Compared with analytical approximations and theoretical predictions, the LSM numerical scheme shows general applicability for heterogeneous porous rocks.     

Test–retest repeatability of [18F]Flortaucipir PET in Alzheimer’s disease and cognitively normal individuals

The aim of this study was to investigate the test–retest (TRT) repeatability of various parametric quantification methods for [¹⁸F]Flortaucipir positron emission tomography (PET). We included eight subjects with dementia or mild cognitive impairment due to Alzheimer’s disease and six cognitively normal subjects. All underwent two 130-min dynamic [¹⁸F]Flortaucipir PET scans within 3 ± 1 weeks. Data were analyzed using reference region models receptor parametric mapping (RPM), simplified reference tissue method 2 (SRTM2) and reference logan (RLogan), as well as standardized uptake value ratios (SUVr, time intervals 40–60, 80–100 and 110–130 min post-injection) with cerebellar gray matter as reference region. We obtained distribution volume ratio or SUVr, first for all brain regions and then in three tau-specific regions-of-interest (ROIs). TRT repeatability (%) was defined as |retest–test|/(average (test + retest)) × 100. For all methods and across ROIs, TRT repeatability ranged from (median (IQR)) 0.84% (0.68–2.15) to 6.84% (2.99–11.50). TRT repeatability was good for all reference methods used, although semi-quantitative models (i.e. SUVr) performed marginally worse than quantitative models, for instance TRT repeatability of RPM: 1.98% (0.78–3.58) vs. SUVr_80–100: 3.05% (1.28–5.52), p < 0.001. Furthermore, for SUVr_80–100 and SUVr_110–130, with higher average SUVr, more variation was observed. In conclusion, while TRT repeatability was good for all models used, quantitative methods performed slightly better than semi-quantitative methods.     

Developing normal number of small segments-activity clouds of the electromyography interference pattern

Guillain-Barré syndrome (GBS) is an inflammatory polyradiculoneuropathy associated with numerous viral infections. Recently, there have been many case reports describing the association between coronavirus disease-2019 (COVID-19) and GBS, but much remains unknown about the strength of the association and the features of GBS in this setting. We reviewed 37 published cases of GBS associated with COVID-19 to summarize this information for clinicians and to determine whether a specific clinical or electrodiagnostic (EDx) pattern is emerging. The mean age (59 years), gender (65% male), and COVID-19 features appeared to reflect those of hospitalized COVID-19 patients early in the pandemic. The mean time from COVID-19 symptoms to GBS symptoms was 11 days. The clinical presentation and severity of these GBS cases was similar to those with non–COVID-19 GBS. The EDx pattern was considered demyelinating in approximately half of the cases. Cerebrospinal fluid, when assessed, demonstrated albuminocytologic dissociation in 76% of patients and was negative for severe acute respiratory distress syndrome–coronavirus-2 (SARS-CoV-2) in all cases. Serum antiganglioside antibodies were absent in 15 of 17 patients tested. Most patients were treated with a single course of intravenous immunoglobulin, and improvement was noted within 8 weeks in most cases. GBS-associated COVID-19 appears to be an uncommon condition with similar clinical and EDx patterns to GBS before the pandemic. Future studies should compare patients with COVID-19–associated GBS to those with contemporaneous non–COVID-19 GBS and determine whether the incidence of GBS is elevated in those with COVID-19.     

Prevalence and vascular risk factors of basal ganglia calcifications in patients at risk for cerebrovascular disease

Background and purposeRisk factors for and meaning of basal ganglia calcifications outside Fahr syndrome are poorly understood. We aimed to assess the prevalence of basal ganglia calcifications and the association with vascular risk factors.Materials and methods1133 patients suspected of acute ischemic stroke from the Dutch acute stroke (DUST) study who underwent thin-slice unenhanced brain CT were analyzed. Basal ganglia calcifications were scored bilaterally as absent, mild (dot), moderate (multiple dots or single artery) and severe (confluent). Uni- and multivariable logistic regression analysis was used to determine possible risk factors (age, gender, history of stroke, smoking, hypertension, diabetes mellitus, hyperlipidemia, body mass index (BMI), renal function and family history of cardiovascular disease under 60 years) for presence of basal ganglia calcifications and ordinal regression analysis for severity of basal ganglia calcifications.ResultsMean age was 67.4 years (SD: 13.8), 56.8% were male. 337 (29.7%) patients had basal ganglia calcifications, of which 196 (58%) were mild, 103 (31%) moderate, 38 (11%) severe. In multivariable logistic regression analysis, age (OR: 1.02, 95% CI 1.01–1.03, P < 0.01) and BMI (OR: 0.95, 95% CI 0.91–0.98, p 0.01) were significantly associated with the presence of basal ganglia calcifications. Ordinal regression analysis gave comparable results. Age (OR: 1.02, 95% CI 1.01–1.03, P < 0.01) and BMI (OR: 0.95, 95% CI 0.92–0.99, P 0.01) were significantly associated with severity of basal ganglia calcifications.ConclusionsIn this study with patients suspected of acute ischemic stroke, basal ganglia calcifications were common and significantly associated with older age and lower BMI.