Factors associated with overdiagnosis of benign pulmonary nodules as malignancy: a retrospective cohort study.

OBJECTIVE: To establish a preoperative model for the differential diagnosis of benign and malignant pulmonary nodules (PNs), and to evaluate the related factors of overdiagnosis of benign PNs at the time of imaging assessments. MATERIALS AND METHODS: In this retrospective study, 357 patients (median age, 52 years; interquartile range, 46-59 years) with 407 PNs were included, who underwent surgical histopathologic evaluation between January 2020 and December 2020. Patients were divided into a training set (n = 285) and a validation set (n = 122) to develop a preoperative model to identify benign PNs. CT scan features were reviewed by two chest radiologists, and imaging findings were categorized. The overdiagnosis rate of benign PNs was calculated, and bivariate and multivariable logistic regression analyses were used to evaluate factors associated with benign PNs that were over-diagnosed as malignant PNs. RESULTS: The preoperative model identified features such as the absence of part-solid and non-solid nodules, absence of spiculation, absence of vascular convergence, larger lesion size, and CYFRA21-1 positivity as features for identifying benign PNs on imaging, with a high area under the receiver operating characteristic curve of 0.88 in the validation set. The overdiagnosis rate of benign PNs was found to be 50%. Independent risk factors for overdiagnosis included diagnosis as non-solid nodules, pleural retraction, vascular convergence, and larger lesion size at imaging. CONCLUSION: We developed a preoperative model for identifying benign and malignant PNs and evaluating factors that led to the overdiagnosis of benign PNs. This preoperative model and result may help clinicians and imaging physicians reduce unnecessary surgery.

Prediction of brain age using quantitative parameters of synthetic magnetic resonance imaging.

Objective: Brain tissue changes dynamically during aging. The purpose of this study was to use synthetic magnetic resonance imaging (syMRI) to evaluate the changes in relaxation values in different brain regions during brain aging and to construct a brain age prediction model. Materials and methods: Quantitative MRI was performed on 1,000 healthy people (≥ 18 years old) from September 2020 to October 2021. T1, T2 and proton density (PD) values were simultaneously measured in 17 regions of interest (the cerebellar hemispheric cortex, pons, amygdala, hippocampal head, hippocampal tail, temporal lobe, occipital lobe, frontal lobe, caudate nucleus, lentiform nucleus, dorsal thalamus, centrum semiovale, parietal lobe, precentral gyrus, postcentral gyrus, substantia nigra, and red nucleus). The relationship between the relaxation values and age was investigated. In addition, we analyzed the relationship between brain tissue values and sex. Finally, the participants were divided into two age groups: < 60 years old and ≥ 60 years old. Logistic regression analysis was carried out on the two groups of data. According to the weight of related factors, a brain age prediction model was established and verified. Results: We obtained the specific reference value range of different brain regions of individuals in different age groups and found that there were differences in relaxation values in brain tissue between different sexes in the same age group. Moreover, the relaxation values of most brain regions in males were slightly higher than those in females. In the study of age and brain relaxation, it was found that brain relaxation values were correlated with age. The T1 values of the centrum semiovale increased with age, the PD values of the centrum semiovale increased with age, while the T2 values of the caudate nucleus and lentiform nucleus decreased with age. Seven brain age prediction models were constructed with high sensitivity and specificity, among which the combined T1, T2 and PD values showed the best prediction efficiency. In the training set, the area under the curve (AUC), specificity and sensitivity were 0.959 [95% confidence interval (CI): 0.945-0.974], 91.51% and 89.36%, respectively. In the test cohort, the above indicators were 0.916 (95% CI: 0.882-0.951), 89.24% and 80.33%, respectively. Conclusion: Our study provides specific reference ranges of T1, T2, and PD values in different brain regions from healthy adults of different ages. In addition, there are differences in brain relaxation values in some brain regions between different sexes, which help to provide new ideas for brain diseases that differ according to sex. The brain age model based on synthetic MRI is helpful to determine brain age.

Heroin Addiction Induces Axonal Transport Dysfunction in the Brain Detected by In Vivo MRI.

Heroin is a highly addictive drug that causes axonal damage. Here, manganese-enhanced magnetic resonance imaging (MEMRI) was used to dynamically monitor axonal transport at different stages of heroin addiction. Rat models of heroin addiction (HA) and prolonged heroin addiction (PHA) were established by injecting rats with heroin at different stages. Heroin-induced learning and memory deficits were evaluated in the Morris water maze (MWM), and MEMRI was used to dynamically evaluate axonal transport in the olfactory pathway. The expression of proteins related to axonal structure and function was also assessed by Western blotting. Transmission electron microscopy (TEM) was used to observe ultrastructural changes, and protein levels of neurofilament heavy chain (NF-H) were analyzed by immunofluorescence staining. HA rats, especially PHA rats, exhibited worse spatial learning and memory than control rats. Compared with HA rats and control rats, PHA rats exhibited significantly longer escape latencies, significantly fewer platform-location crossings, and significantly more time in the target quadrant during the MWM test. Mn2+ transport was accelerated in HA rats. PHA rats exhibited severely reduced Mn2+ transport, and the axonal transport rate (ATR) was significantly lower in these rats than in control rats (P < 0.001). The levels of cytoplasmic dynein and kinesin-1 were significantly decreased in the PHA group than in the control group (P < 0.001); additionally, the levels of energy-related proteins, including cytochrome c oxidase (COX) IV and ATP synthase subunit beta (ATPB), were lower in the PHA group (P < 0.001). The brains of heroin-exposed rats displayed an abnormal ultrastructure, with neuronal apoptosis and mitochondrial dysfunction. Heroin exposure decreased the expression of NF-H, as indicated by significantly reduced staining intensities in tissues from HA and PHA rats (P < 0.05). MEMRI detected axonal transport dysfunction caused by long-term repeated exposure to heroin. The main causes of axonal transport impairment may be decreases in the levels of motor proteins and mitochondrial dysfunction. This study shows that MEMRI is a potential tool for visualizing axonal transport in individuals with drug addictions, providing a new way to evaluate addictive encephalopathy.

Cranial irradiation-induced impairment of axonal transport and sexual function in male rats and imaging of the olfactory pathway by MRI.

PURPOSE: The aim of this study was to evaluate the effect of radiation-induced brain injury (RIBI) on axonal transport (AT) and sexual function. METHODS AND MATERIALS: Adult male rats received whole-brain radiation with a total dose of 30 Gy (15 Gy with 2 fractions) to build a RIBI model. Foraging behavior and sexual function were assessed, and MRI was performed 8 weeks after brain irradiation. MRI was performed in the early and delayed phases after perfusion of MnCl2 into the rat nostril. The levels of motor proteins and proteins involved in energy metabolism and AT were determined by Western blotting. The levels of sex hormones in the blood were measured by ELISA. Ultrastructural analysis was performed with a transmission electron microscope. RESULTS: The foraging ability of rats was reduced after brain irradiation, and the foraging time of the radiation group was longer than that of the control group (P < 0.05). The sexual function of rats in the radiation group was markedly decreased. Compared with control rats, radiation-treated rats showed significant decreases in serum testosterone, FSH, LH, and GnRH levels (P < 0.001). Mn2+ uptake in the olfactory bulb (OB) in the early phase and delayed phase was lower in the radiation group than in the control group (P < 0.05). The AT rate in the lateral olfactory tracts (LOT) and the transsynaptic AT rate were significantly lower in the irradiated rats than in the control rats (P < 0.05). The levels of the motor proteins kinesin-1 and cytoplasmic dynein were significantly decreased in the irradiation group (P < 0.05). The expression of the energy metabolism-related proteins ATPB and COX IV was significantly lower in the irradiated rats than in the control rats (P < 0.05). Apoptosis and synaptic damage were observed after irradiation. CONCLUSION: MRI of the olfactory pathway can be used to assess AT impairment in RIBI models. AT deficits secondary to radiation damage are the result of multiple factors, including declines in motor protein levels, neuronal apoptosis, synaptic damage and energy metabolism dysfunction. Cranial irradiation-induced sexual dysfunction was associated with decreased sex hormone levels secondary to hypothalamic-pituitary-gonadal axis injury.