Preoperative prediction of perineural invasion of rectal cancer based on a magnetic resonance imaging radiomics model: A dual-center study.

BACKGROUND: Perineural invasion (PNI) has been used as an important pathological indicator and independent prognostic factor for patients with rectal cancer (RC). Preoperative prediction of PNI status is helpful for individualized treatment of RC. Recently, several radiomics studies have been used to predict the PNI status in RC, demonstrating a good predictive effect, but the results lacked generalizability. The preoperative prediction of PNI status is still challenging and needs further study. AIM: To establish and validate an optimal radiomics model for predicting PNI status preoperatively in RC patients. METHODS: This retrospective study enrolled 244 postoperative patients with pathologically confirmed RC from two independent centers. The patients underwent pre-operative high-resolution magnetic resonance imaging (MRI) between May 2019 and August 2022. Quantitative radiomics features were extracted and selected from oblique axial T2-weighted imaging (T2WI) and contrast-enhanced T1WI (T1CE) sequences. The radiomics signatures were constructed using logistic regression analysis and the predictive potential of various sequences was compared (T2WI, T1CE and T2WI + T1CE fusion sequences). A clinical-radiomics (CR) model was established by combining the radiomics features and clinical risk factors. The internal and external validation groups were used to validate the proposed models. The area under the receiver operating characteristic curve (AUC), DeLong test, net reclassification improvement (NRI), integrated discrimination improvement (IDI), calibration curve, and decision curve analysis (DCA) were used to evaluate the model performance. RESULTS: Among the radiomics models, the T2WI + T1CE fusion sequences model showed the best predictive performance, in the training and internal validation groups, the AUCs of the fusion sequence model were 0.839 [95% confidence interval (CI): 0.757-0.921] and 0.787 (95%CI: 0.650-0.923), which were higher than those of the T2WI and T1CE sequence models. The CR model constructed by combining clinical risk factors had the best predictive performance. In the training and internal and external validation groups, the AUCs of the CR model were 0.889 (95%CI: 0.824-0.954), 0.889 (95%CI: 0.803-0.976) and 0.894 (95%CI: 0.814-0.974). Delong test, NRI, and IDI showed that the CR model had significant differences from other models (P < 0.05). Calibration curves demonstrated good agreement, and DCA revealed significant benefits of the CR model. CONCLUSION: The CR model based on preoperative MRI radiomics features and clinical risk factors can preoperatively predict the PNI status of RC noninvasively, which facilitates individualized treatment of RC patients.

The CT-guided percutaneous drainage of pancreatic pseudocyst accompanied by pseudoaneurysm: A case report.

RATIONALE: This case report discusses the CT-guided percutaneous drainage of a pancreatic pseudocyst accompanied by a pseudoaneurysm. Pancreatic pseudocysts can erode the peripancreatic artery and produce pseudoaneurysms. This is rare, but it can be life-threatening. PATIENT CONCERNS: The case presented involves a 58-year-old female who was diagnosed with pancreatic cancer and underwent surgical treatment. She presented with hematochezia, dizziness, and hypodynamic findings with no obvious cause. Imaging revealed a pancreatic pseudocyst and small arterial aneurysms. To reduce the risk of aneurysm rupture, the patient underwent transcatheter arterial coil embolization. Three days later, CT-guided catheter drainage was performed to reduce the erosion of the arterial wall caused by pancreatic fluid. DIAGNOSES: The contrast-enhanced-CT imaging showed a round, slightly high-density lesion in the cyst, suggesting the presence of a pseudoaneurysm. INTERVENTIONS: The patient was sent for another transcatheter arterial embolization with coils and n-butyl-2-cyanoacrylate. OUTCOMES: After receiving the transcatheter arterial embolization, the patient had no serious bleeding or other complications. LESSONS: Early detection and accurate assessment of pseudoaneurysms are essential for appropriate management. This case shows that contrast-enhanced CT is necessary before CT-guided percutaneous drainage of pancreatic pseudocysts. It also shows that, due to the many complications that pancreatic pseudocysts may cause, appropriate treatment of pseudocysts complicated with pseudoaneurysm has important clinical significance.

MR Imaging of Migrated Nucleus Pulposus after Collagenase Injection of Lumbar Disc Herniation: A Case Report.

Magnetic resonance images (MRI) of migrated nucleus pulposus after collagenase treatment of lumbar disc herniation are rarely published. Here, we describe a 65-year-old woman with L5-S1 intervertebral disc herniation on the rear left. The patient was treated with a lumbar disc collagenase injection, and the pain was relieved. Two weeks later, the patient suddenly developed pain again after engaging in weight-bearing activity. Lumbar MRI showed a nodule in the spinal canal at the L5-S1 level. The patient underwent surgical treatment two days later. Pathology showed that the nodule was nucleus pulposus tissue. Teaching point: It is important to understanding the MR manifestations of migrated nucleus pulposus after collagenase treatment to prevent such misdiagnosis.

Black phosphorus flakes covered microfiber for Q-switched ytterbium-doped fiber laser.

We demonstrate a passively Q-switched ytterbium-doped fiber laser based on black phosphorus (BP) flakes covered microfiber. The BP saturable absorber is fabricated by sandwiching a microfiber between two pieces of polydimethylsiloxane supported BP flakes film, which is prepared by the mechanical exfoliation method. In this case the BP flakes can be well protected from the action of air and moisture. By incorporating BP flakes covered microfiber into a ytterbium-doped ring fiber laser, stable and reliable Q-switched operation at 1064 nm can be realized via interaction between few-layers BP flakes and the evanescent field of the laser. The laser allows Q-switched pulse generation with a repetition rate in the range of 26-76 kHz and a pulse duration in the range of 5.5-2.0 µs, by varying the pump power from 38 mW to 100 mW.

[Characteristics of rubidium forward degenerate four-wave mixing (FDFWM) influenced by the matrix effect of chloride brine in graphite furnace].

Rb is mainly extracted from brine. The authors studied the matrix effect of chloride brine (NaCl, CaCl2, KCl and MgCl2) on FDFWM (Forward phase-matching degenerate four-wave mixing) of Rb in the graphite furnace. The Rb and other chloride brine concentrations dependences of FDFWM were investigated respectively. The results indicate that with the increase in Rb concentration, FDFWM increases and reaches the highest at 80 ng x mL(-1). With the concentration of Rb sample further increasing, the FDFWM intensity drops. It was also found that when the Rb concentration is low, FDFWM signal is suppressed by the chloride brine, and the suppressing effect gets stronger with the increase in the chloride brine concentration. However, when the Rb concentration is high, FDFWM signal is first enhanced and then suppressed with the increase in the chloride brine concentration. The Cl- interference and Rb ionization in the graphite furnace were employed to explain the experimental results. This work is of important meaning in extracting and analyzing Rb in brine.

Geometries and electronic properties of the neutral and charged rare earth Yb-doped Si(n) (n = 1-6) clusters: a relativistic density functional investigation.

The neutral and charged YbSi(n) (n = 1-6) clusters considering different spin configurations have been systematically investigated by using the relativistic density functional theory with generalized gradient approximation. The total bonding energies, equilibrium geometries, Mulliken populations (MP), Hirshfeld charges (HC), fragmentation energies, and highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps are calculated and discussed. The optimized geometries indicate that the most stable YbSi(n) (n = 1-6) clusters keep basically the analogous frameworks as the low-lying Si(n)(+1) clusters, while the charged species deviate from their neutral counterparts, and that the doped Yb tends to occupy the substitutional site of the neutral and charged YbSi(n) isomers. The relative stabilities are investigated in terms of the calculated fragmentation energies, exhibiting enhanced stabilities for the remarkably stable neutral and charged YbSi2 and YbSi5 clusters. Furthermore, the calculated MP and HC values show that the charges of the neutral and charged YbSi(n) clusters transfer from the Yb atom to Si(n) atoms and the Yb atom acts as an electron donor, and that the f orbitals of the Yb atom in the neutral and charged YbSi(n) clusters behave as core without involvement in chemical bonding. The calculated HOMO-LUMO gaps indicate that the YbSi2 and YbSi4+ clusters have stronger chemical stabilities. Comparisons of the Yb-doped Si(n) (n = 1-6) with available theoretical results of transition-metal-doped silicon clusters are made. The growth pattern is investigated also.