Long-term outcomes and prognostic factors in patients with mild hemoptysis.

OBJECTIVE: The aim of this retrospective study was to observe the long-term outcomes of conservative treatment and bronchial artery embolization (BAE) in patients with mild hemoptysis and to analyze the risk factors associated with hemoptysis recurrence. METHODS: Patients with mild hemoptysis from January 2005 to January 2016 were enrolled in this study. The patients' medical records, including smoking history, etiologic diseases, bronchoscopic findings, mortality, BAE information, and follow-up data of recurrent hemoptysis, were reviewed and analyzed. RESULTS: A total of 288 patients with mild hemoptysis were included in this study. Of them, 71 patients (24.7%) underwent BAE and 217 patients (75.3%) were treated conservatively. The clinical success rate of BAE was 98.6%, with a low minor complication rate of 5.6%. Bronchoscopy before treatments was performed in 237 patients (82.3%). Fifty-five patients (19.1%) experienced recurrent hemoptysis during a median follow-up period of 2.4years (interquartile range: 1.0-4.4years). Patients who showed active bleeding or blood clots on bronchoscopy had a significantly lower recurrence-free survival rate than patients with no bronchoscopic evidence of bleeding or blood clots (p=0.012). The risk factors affecting recurrence were heavy smoking (p=0.002, hazard ratio [HR]: 3.57), aspergillosis (p=0.035, HR: 6.01), and bronchoscopic findings of active bleeding (p=0.016, HR: 3.29) or blood clots (p=0.012, HR: 2.77). CONCLUSIONS: The recurrence rate of hemoptysis was not negligible in patients with mild hemoptysis. BAE can be considered in patients with a high risk of recurrence.

Sliding time of flight: sliding time of flight MR angiography using a dynamic image reconstruction method.

PURPOSE: To obtain three-dimensional (3D) MR angiography having high contrast between vessel and stationary background tissue, a novel technique called sliding time of flight (TOF) is proposed. METHODS: The proposed method relies on the property that flow-related enhancement (FRE) is maximized at the blood-entering slice in an imaging slab. For the proposed sliding TOF, a sliding stack-of-stars sampling and a dynamic MR image reconstruction algorithm were developed. To verify the performance of the proposed method, in vivo study was performed and the results were compared with multiple overlapping thin 3D slab acquisition (MOTSA) and sliding interleaved ky (SLINKY). RESULTS: In MOTSA and SLINKY, the variation of FRE resulted in severe venetian blind (MOTSA) or ghost (SLINKY) artifacts, while the vessel-contrast increased as the flip angle of radiofrequency (RF) pulses increased. On the other hand, the proposed method could provide high-contrast angiograms with reduced FRE-related artifacts. CONCLUSION: The sliding TOF can provide 3D angiography without image artifacts even if high flip angle RF pulses with thick slab excitation are used. Although remains of subsampling artifacts can be present in the reconstructed images, they can be reduced by MIP operation and resolved further by regularization techniques.

Size-controlled construction of magnetic nanoparticle clusters using DNA-binding zinc finger protein.

Nanoparticle clusters (NPCs) have attracted significant interest owing to their unique characteristics arising from their collective individual properties. Nonetheless, the construction of NPCs in a structurally well-defined and size-controllable manner remains a challenge. Here we demonstrate a strategy to construct size-controlled NPCs using the DNA-binding zinc finger (ZnF) protein. Biotinylated ZnF was conjugated to DNA templates with different lengths, followed by incubation with neutravidin-conjugated nanoparticles. The sequence specificity of ZnF and programmable DNA templates enabled a size-controlled construction of NPCs, resulting in a homogeneous size distribution. We demonstrated the utility of magnetic NPCs by showing a three-fold increase in the spin-spin relaxivity in MRI compared with Feridex. Furthermore, folate-conjugated magnetic NPCs exhibited a specific targeting ability for HeLa cells. The present approach can be applicable to other nanoparticles, finding wide applications in many areas such as disease diagnosis, imaging, and delivery of drugs and genes.

Comparison of vascular access patency and patient survival between native arteriovenous fistula and synthetic arteriovenous graft according to age group.

INTRODUCTION: Arteriovenous fistula (AVF) is historically known to be the ideal option for vascular access (VA) for hemodialysis compared with arteriovenous graft (AVG). However, this approach has been recently questioned in the aging population because of their poor vessel quality and multiple comorbidities. METHODS: Data from a total of 2200 patients from the VA category of The Catholic Medical Center nephrology registry from March 2009 to February 2017 were analyzed. We compared VA patency and patient survival between two groups, AVF and AVG, according to age. FINDINGS: Compared with the AVG group, survival benefit in the AVF group continued even in patients ≥80 years. In the whole population, all the primary patency (PP), primary-assisted patency (PAP), and secondary patency (SP) measures were superior in the AVF group. With regard to subgroups, PP was comparable between the two groups in patients ≥65 years, whereas PAP and SP were superior in the AVF group even in septuagenarian patients who are from 70 to 79 years old. In patients ≥80 years, all the patency measures were comparable between the two groups. When the separate comparison of lower-arm AVF (or upper-arm AVF) and AVG, lower-arm AVF failed to demonstrate its superiority in any kind of patency in septuagenarian patients compared with AVG, whereas upper-arm AVF demonstrated its superiority in PAP and SP in septuagenarian patients. However, even upper-arm AVF failed to demonstrate its superiority in any kind of patency in patients ≥80 years. DISCUSSION: Arteriovenous fistula if using upper-arm vessel showed the superior VA patency up to septuagenarian patients, whereas, in HD patients ≥80 years, AVF and AVG were comparable in VA patency.

Central venous disease in hemodialysis patients.

Central venous disease (CVD) is difficult to treat and often resistant to treatment. In CVD, hemodialysis vascular access should sometimes be abandoned, or in serious cases, the patient's life may be threatened. Therefore, prevention is ideal. However, as the prevalence of chronic kidney disease (CKD) has increased steadily with population aging, CKD patients with a peripherally inserted central catheter (PICC) are encountered frequently. PICCs can cause CVD, and the basilic vein, which is regarded as the important last option for native arteriovenous fistula (AVF) creation in end-stage renal disease (ESRD) patients, is destroyed frequently after its use as the entry site of PICC. The most well-established risk factors for CVD are a history of central venous catheter (CVC) insertion and its duration of use. Therefore, to reduce the incidence of CVD, catheterization in the central vein (CV) should be minimized, along with its duration of use. In this review, we will first explain the basic territories of the CV and introduce its pathophysiology, clinical features, and advanced treatment options. Finally, we will emphasize prevention of CVD.

The effect of vascular access type on intra-access flow volume during hemodialysis.

INTRODUCTION: Previous studies have revealed that vascular access resistance is constant during hemodialysis, but differs according to vascular access type. It is possible that intra-access flow volume (Qac) variation during hemodialysis may also differ according to vascular access type. We conducted this study to investigate whether there are differences in Qac according to vascular access type during hemodialysis. METHODS: A total of 58 lower-arm arteriovenous fistula, 14 lower-arm arteriovenous graft, 27 upper-arm arteriovenous fistula, and 45 upper-arm arteriovenous graft cases were studied. Three consecutive Qac values (at 30, 120, and 240 min after the start of hemodialysis) were measured in each patient by the ultrasound dilution technique. Variations in Qac over time were analyzed using repeated measures analysis of variance and multivariate regression analyses, to assess the impact of different factors on Qac variation. RESULTS: The repeated measures analysis of variance revealed that a significant interaction exists between time and vascular access type (p < 0.001). This suggests that vascular access type affects Qac change (%) variation over time during hemodialysis. In a multivariate analysis, mean arterial pressure change during hemodialysis (p = 0.009), access type (p < 0.001), and access location (p < 0.001) were independent variables causing Qac change variation. CONCLUSION: This study showed that there is a significant difference in Qac variation according to vascular access type during hemodialysis and that arteriovenous graft (vs arteriovenous fistula) and the lower-arm location (vs upper arm) were associated with a decrease in Qac during hemodialysis. This suggests that consideration of vascular access type is required to minimize Qac variation during hemodialysis.

Exchange over the guidewire from non-tunneled to tunneled hemodialysis catheters can be performed without patency loss.

PURPOSE: The exchange from a non-tunneled hemodialysis catheter to a tunneled one over a guidewire using a previous venotomy has been reported to be safe. However, some concerns that it may increase infection risk prevent its clinical application. This approach seems particularly useful for acute kidney injury patients requiring initial renal replacement therapy, in whom we frequently worry about the choice of non-tunneled versus tunneled catheters. MATERIALS AND METHODS: From March 2012 to February 2016, 88 cases to receive the over-the-guidewire exchange method from a non-tunneled to a tunneled catheter and 521 cases to receive de novo tunneled catheter placement from the hemodialysis vascular access cohort were compared retrospectively. RESULTS: The immediate complication, later catheter dysfunction requiring replacement, and infection rates were comparable between the two groups. Newly placed tunneled catheter survival in the over-the-guidewire exchange group was comparable with survival in the de novo tunneled catheter group (p = 0.24). In addition, when we compared the same two methods among only intensive care unit patients; they remained similar (p = 0.19). CONCLUSION: An exchange with the over-the-guidewire method from a non-tunneled to a tunneled catheter was comparable to a de novo catheter placement technique. Therefore, this method should be viewed more favorably and should especially be considered for acute kidney injury patients.

Computed tomography and magnetic resonance imaging evaluation of lymph node metastasis in early colorectal cancer.

AIM: To assess the role of computed tomography (CT) and magnetic resonance imaging (MRI) and establish imaging criteria of lymph node metastasis in early colorectal cancer. METHODS: One hundred and sixty patients with early colorectal cancer were evaluated for tumor location, clinical history of polypectomy, depth of tumor invasion, and lymph node metastasis. Two radiologists assessed preoperative CT and/or MRI for the primary tumor site detectability, the presence or absence of regional lymph node, and the size of the largest lymph node. Demographic, imaging, and pathologic findings were compared between the two groups of patients based on pathologic lymph node metastasis and optimal size criterion was obtained. RESULTS: The locations of tumor were ascending, transverse, descending, sigmoid colon, and rectum. One hundred and sixty early colorectal cancers were classified into 3 groups based on the pathological depth of tumor invasion; mucosa, submucosa, and depth unavailable. A total of 20 (12.5%) cancers with submucosal invasion showed lymph node metastasis. Lymph nodes were detected on CT or MRI in 53 patients. The detection rate and size of lymph nodes were significantly higher (P = 0.000, P = 0.044, respectively) in patients with pathologic nodal metastasis than in patients without nodal metastasis. Receiver operating curve analysis showed that a cut-off value of 4.1 mm is optimal with a sensitivity of 78.6% and specificity of 75%. CONCLUSION: The short diameter size criterion of ≥ 4.1 mm for metastatic lymph nodes was optimal for nodal staging in early colorectal cancer.

Isotropic diffusion weighting for measurement of a high-resolution apparent diffusion coefficient map using a single radial scan in MRI.

This work proposes an isotropic diffusion weighting method for a high-resolution diffusion-weighted image and for a high-resolution apparent diffusion coefficient (ADC) map using a single radial scan in MRI. By using a conventional radial imaging technique, a high-resolution diffusion-weighted (DW) image can be obtained at the cost of a long imaging time. To reduce the imaging time, the proposed method acquires a DW image by altering the diffusion gradient directions for each radial spoke. The acquisition order and directions of the diffusion gradients for an accurate DW image and an ADC map are also proposed by modifying the golden angle ratio in 3D space. In addition, an individual-direction diffusion-weighted (id-DW) image can also be obtained by a diffusion gradient direction, which is one of the multiple directions used in isotropic diffusion weighting. Computer simulations and experiment results show that the proposed method is more accurate and faster than the conventional radial diffusion-weighted imaging. This study suggests that the proposed isotropic diffusion-weighted imaging can be used to obtain a DW image and a high-resolution ADC map accurately in a single radial scan, while reducing the artifacts caused by the diffusion anisotropy, compared to the diffusion-weighted echo-planar-imaging.

An iterative reconstruction method of complex images using expectation maximization for radial parallel MRI.

In MRI (magnetic resonance imaging), signal sampling along a radial k-space trajectory is preferred in certain applications due to its distinct advantages such as robustness to motion, and the radial sampling can be beneficial for reconstruction algorithms such as parallel MRI (pMRI) due to the incoherency. For radial MRI, the image is usually reconstructed from projection data using analytic methods such as filtered back-projection or Fourier reconstruction after gridding. However, the quality of the reconstructed image from these analytic methods can be degraded when the number of acquired projection views is insufficient. In this paper, we propose a novel reconstruction method based on the expectation maximization (EM) method, where the EM algorithm is remodeled for MRI so that complex images can be reconstructed. Then, to optimize the proposed method for radial pMRI, a reconstruction method that uses coil sensitivity information of multichannel RF coils is formulated. Experiment results from synthetic and in vivo data show that the proposed method introduces better reconstructed images than the analytic methods, even from highly subsampled data, and provides monotonic convergence properties compared to the conjugate gradient based reconstruction method.