Background Primary lacrimal sac melanoma is an extremely rare condition with fewer than 50 cases reported so far. Clinically, its symptoms resemble those of dacryocystitis, leading to frequent misdiagnosis. During diagnosis, imaging examination is often performed to differentiate tumors from inflammation. In this report, we present a case of primary lacrimal sac melanoma and summarize the CT and MRI characteristics of lacrimal sac melanoma. Case presentation We report a 50-year-old female patient who had undergone a dacryocystectomy for the left lacrimal sac mass. Postoperative pathological examination confirmed the presence of primary malignant melanoma. Three months later, a lump in the lacrimal sac area was found. The patient underwent CT and MR examinations. CT scan demonstrated a partially well-defined soft mass in the fossa of left lacrimal sac extending into the nasolacrimal duct and anterior ethmoid sinus. MRI revealed an intermediate signal intensity on T1 and iso-or hyper-signal on T2 weighted images. Histopathological examination on biopsy confirmed recurrence of primary lacrimal sac melanoma. Discussion and conclusions None has described the CT and MR findings of primary lacrimal sac melanoma so far. Typically, MR images show hyperintensity signal on T1-weighted images and hypointense signal on T2-weighted images owing to the paramagnetic properties of melanin. In contrast to previous reports and the present case, most cases do not present these typical signals. Thus, reporting such radiological findings is important to create awareness on variant images of primary lacrimal sac melanoma. This will reduce misdiagnosis and mistreatment.

BackgroundContrast-enhanced MRI can be used to identify patients with hepatocellular carcinoma (HCC). However, studies around the world have found differing diagnostic accuracies for the technique. Hence, we designed this meta-analysis to assess the accuracy of contrast-enhanced MRI for HCC diagnosis.MethodsWe conducted a systematic search for all studies reporting the diagnostic accuracy of contrast-enhanced MRI for HCC in the databases of MEDLINE, EMBASE, Cochrane Library, Web of Science, SCOPUS, ScienceDirect, and Google Scholar from inception until January 2021. We used the “Midas” package from the STATA software to perform the meta-analysis.ResultsOur study was based on 21 publications with 5,361 patients. The pooled HCC diagnosis sensitivity and specificity were 75% (95% CI, 70%–80%) and 90% (95% CI, 88%–92%), respectively, for gadoxetic acid-enhanced MRI; and they were 70% (95% CI, 57%–81%) and 94% (95% CI, 85%–97%), respectively, for MRI with extracellular contrast agents (ECA-MRI). We found significant heterogeneity with a significant chi-square test and an I2 statistic >75%. We also found significant publication bias as per Deeks’ test results and funnel plot.ConclusionWe found that both types of contrast-enhanced MRI are accurate diagnostic and surveillance tools for HCC and offer high sensitivity and specificity. Further studies on different ethnic populations are required to strengthen our findings.

Objective To assess the potential of intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) in monitoring renal changes in a diabetic nephropathy (DN) rat model with acute kidney injury (CI-AKI) induced by iso-osmotic contrast media (IOCM) and low-osmotic contrast media (LOCM). Methods A diabetic nephropathy rat model was established, and the animals were randomly split into the LOCM group and IOCM group (n = 13 per group), with iopamidol and iodixanol injection, respectively (4 g iodine/kg). MRI including IVIM and DKI was performed 24 h before contrast medium injections (baseline) and 1, 24, 48, and 72 h after injections. Changes in pure molecular diffusion (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), mean diffusion (MD), mean kurtosis (MK), serum creatinine (SCr) and urea nitrogen (BUN), histopathology alterations, and α-smooth muscle actin (α-SMA) expression were assessed. Inter-observer agreement was evaluated using the intraclass correlation coefficient (ICC). Results Compared against baseline levels, significant decreases in D, D*, and f were observed in all anatomical kidney compartments after contrast injection (p < 0.05). MD in the cortex (CO) and outer medullary (OM) gradually decreased, and MK in OM gradually increased 24–72 h after injection. D, D*, f, and MD were negatively correlated with the histopathologic findings and α-smooth muscle actin (α-SMA) expression in all anatomical kidney compartments. Inter-observer reproducibility was generally good (ICCs ranging from 0.776 to 0.979). Conclusions IVIM and DKI provided noninvasive imaging parameters, which might offer effective detection of CI-AKI in DN.

BACKGROUND Type 2 diabetes mellitus (T2DM) has been strongly associated with an increased risk of developing cognitive dysfunction and dementia. The mechanisms of diabetes-associated cognitive dysfunction (DACD) have not been fully elucidated to date. Some studies proved lower cerebral blood flow (CBF) in the hippocampus was associated with poor executive function and memory in T2DM. Increasing evidence showed that diabetes leads to abnormal vascular endothelial growth factor (VEGF) expression and CBF changes in humans and animal models. In this study, we hypothesized that DACD was correlated with CBF alteration as measured by three-dimensional (3D) arterial spin labeling (3D-ASL) and VEGF expression in the hippocampus. AIM To assess the correlation between CBF (measured by 3D-ASL and VEGF expression) and DACD in a rat model of T2DM. METHODS Forty Sprague-Dawley male rats were divided into control and T2DM groups. The T2DM group was established by feeding rats a high-fat diet and glucose to induce impaired glucose tolerance and then injecting them with streptozotocin to induce T2DM. Cognitive function was assessed using the Morris water maze experiment. The CBF changes were measured by 3D-ASL magnetic resonance imaging. VEGF expression was determined using immunofluorescence. RESULTS The escape latency time significantly reduced 15 wk after streptozotocin injection in the T2DM group. The total distance traveled was longer in the T2DM group; also, the platform was crossed fewer times. The percentage of distance in the target zone significantly decreased. CBF decreased in the bilateral hippocampus in the T2DM group. No difference was found between the right CBF value and the left CBF value in the T2DM group. The VEGF expression level in the hippocampus was lower in the T2DM group and correlated with the CBF value. The escape latency negatively correlated with the CBF value. The number of rats crossing the platform positively correlated with the CBF value. CONCLUSION Low CBF in the hippocampus and decreased VEGF expression might be crucial in DACD. CBF measured by 3D-ASL might serve as a noninvasive imaging biomarker for cognitive impairment associated with T2DM.