Compared to the existing noninvasive methods, temporal interference (TI) current stimulation is an emerging noninvasive neuromodulation technique that can improve the ability to focus an electrical ...field on a target nerve. Induced TI field distribution depends on the anatomical structure of individual neurons, and thus the electrode and current optimization to enhance the field focus must reflect these factors. The current study presents a TI field optimization framework for focusing the stimulation energy on the target tibial nerve through extensive electrical simulations, factoring in individual anatomical differences. We conducted large-scale in-silico experiments using realistic models based on magnetic resonance images of human subjects to evaluate the effectiveness of the proposed methods for tibial nerve stimulation considering overactive bladder (OAB) treatment. The electrode position and current intensity were optimized for each subject using an automated algorithm, and the field-focusing performance was evaluated based on the maximum intensity of the electric fields induced at the target nerve compared with the electric fields in the neighboring tissues. Using the proposed optimization framework, the focusing ability increased by 12% when optimizing the electrode position. When optimizing both the electrode position and current, this capability increased by 11% relative to electrode position optimization alone. These results suggest the significance of optimizing the electrode position and current intensity for focusing TI fields at the target nerve. Our electrical simulation-based TI optimization framework can be extended to enable personalized peripheral nerve stimulation therapy to modulate peripheral nerves.
Background
Gastrointestinal stromal tumors (GISTs) and non-GIST subepithelial tumors (SETs) account for about 75 and 25 % of gastric hypoechoic SETs ≥2 cm, respectively. Therefore, identifying ...preoperative predictive factors for GISTs are required to refine surgical indications.
Methods
We performed a retrospective review of 375 surgically resected gastric hypoechoic SETs ≥2 cm. Demographic data and tumor characteristics based on upper endoscopy and CT findings were compared between GIST and non-GIST SETs originating from muscularis propria layer (leiomyomas, Schwannomas, glomus tumors, and ectopic pancreas).
Results
In cardia, leiomyomas were found twice more frequently than GISTs (63.6 versus 31.8 %). Perilesional lymph node enlargement (PLNE) was found only in patients with GIST or Schwannomas. Patients with GIST showed a significantly lower rate of PLNE than those with Schwannomas (3.5 versus 29.0 %). In multivariate analysis, tumor site outside cardia (odds ratio, 9.157), absence of PLNE (odds ratio, 11.519), old age, large tumor size, exophytic growth pattern, and ulceration or dimpling were identified as independent preoperative predictive factors for GISTs versus non-GIST SETs.
Conclusions
The effort for preoperative pathologic diagnosis such as endosonography-guided tissue sampling might be positively considered for SETs at cardia and SETs with PLNE where the possibility of GIST is low.
The objective of our study was to evaluate the added value of diffusion-weighted imaging (DWI) for distinguishing between malignant and benign focal splenic lesions.
This study included 53 patients ...with 11 malignant and 42 benign splenic lesions who underwent gadoxetic acid-enhanced MRI and DWI. Qualitative and quantitative analyses were conducted for splenic lesions. Two blinded observers evaluated the two image sets--that is, the conventional MR images alone versus the combined conventional MR and DW images--and scored their confidence for malignancy of splenic lesions. The Fisher exact test and Mann-Whitney U test were performed, and diagnostic performance values (ROC curve analysis) were evaluated.
All malignant lesions showed a progressive hypovascular enhancement pattern, whereas the hypervascular enhancement patterns were shown in only benign lesions (n = 20, 47.6%) (p < 0.05). The mean apparent diffusion coefficient (ADC) of the malignant lesions (0.73 × 10(-3) mm(2)/s) was significantly lower than that of the benign lesions (1.21 × 10(-3) mm(2)/s) (p < 0.001). The addition of DW images to conventional MR images showed a significant improvement for predicting malignant splenic lesions (area under ROC curve Az without DW images vs with DW images: 0.774 vs 0.983 for observer 1 and 0.742 vs 0.986 for observer 2) (p < 0.001). In addition, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of combined conventional MR and DW images were higher than those of conventional MR images alone.
The addition of DWI to conventional MRI improves differentiation of malignant from benign splenic lesions.
To assess factors affecting tumor visibility on planning ultrasound (US) for percutaneous radiofrequency (RF) ablation to treat small hepatocellular carcinomas (HCCs) primarily detected on computed ...tomography (CT) or magnetic resonance (MR) imaging.
Patients referred for planning US for percutaneous RF ablation between September 2008 and June 2009 were prospectively enrolled from nine institutions in Korea. The first small (≤ 3 cm) single HCC or new single HCC after treatment was included. The study enrolled 898 patients (684 men and 214 women, age range 32-86 years). HCCs that were invisible on planning US were compared with visible HCCs with respect to tumor size, distance between the tumor and the diaphragm, subcapsular location, etiology of liver disease, liver cirrhosis, macronodular cirrhosis on US, ascites, Child-Pugh class, serum alpha fetoprotein (AFP) level, body mass index (BMI), previous treatments for HCC, previous chemoembolization treatments for HCC, institutions, and experience of radiologists.
Among 898 HCCs, 671 (74.7%) were visible on the planning US. In multivariate analysis, tumor size, distance between the tumor and the diaphragm, liver cirrhosis, and macronodular cirrhosis were statistically significant factors affecting US detection (each P < .05).
Smaller tumors, subphrenic location of the tumor, liver cirrhosis, and macronodular cirrhosis were independent predictors of invisible tumors on planning US.
As the clinical role of radiofrequency ablation (RFA) of the liver grows, the importance of radiologic imaging after liver RFA to depict the diversity of post-RFA manifestations is also increasing. ...Because RFA induces coagulation necrosis of the hepatic parenchyma, cross-sectional imaging studies, in principle, demonstrate an area with a defect in contrast enhancement. However, for various reasons, such as the occurrence of a complication, the RFA zone may demonstrate different patterns or be accompanied by other abnormalities. In this investigation, a large number of imaging studies performed after more than 4000 procedures of liver RFA during the past 10-year period were reviewed, and various radiologic manifestations of the RFA zone were compiled. Herein, the basic principles of RFA, as well as the histopathologic features of coagulation necrosis of the liver, are catalogued to provide a more complete understanding of such changes. Through this review, the reader will become more familiar with the usual and unusual radiologic findings of coagulation necrosis induced by RFA in the liver. This increased familiarity will not only facilitate the daily practice of radiology but also deepen understanding of the therapeutic modality of RFA.
We evaluated the long-term survival results and safety of percutaneous radiofrequency ablation (RFA) for recurrent hepatocellular carcinoma (HCC) after hepatectomy, and assessed the prognostic ...factors that can influence its long-term therapeutic results.
One hundred and two patients, who had 119 recurrent HCC in their livers, underwent ultrasound-guided percutaneous RFA. All the patients had a history of hepatic resection as a first-line treatment modality for HCC. The mean diameter of the recurrent tumors was 2.0 cm (range, 0.8-5.0 cm). We evaluated the effectiveness rates, local tumor progression rates, survival rates, and complications. We also assessed the prognostic factors of the survival rates by using Cox proportional hazard models.
The primary effectiveness rate was 93.3% (111 of 119). The cumulative rates of local tumor progression at 1, 3, and 5 years were 6.0, 8.6, and 11.9%, respectively. The cumulative survival rates at 1, 2, 3, 4, and 5 years were 93.9, 83.7, 65.7, 56.6, and 51.6%, respectively. Patients with a lower serum alpha-fetoprotein (AFP) level (<or=100 microg/L) before RFA or with small resected tumors (<or=5 cm) demonstrated better survival results (P < .05). There was only one major complication (liver abscess, 1.0% per treatment) during the follow-up period. There were no procedure-related deaths.
Percutaneous RFA is an effective and safe treatment modality for intrahepatic recurrent HCC after hepatectomy. Serum AFP level before RFA and resected tumor size were significant prognostic predictors of long-term survival.
Image-guided radiofrequency (RF) ablation has been used to treat both resectable and nonresectable hepatic tumors. A precise imaging assessment of the therapeutic response and of any complications is ...mandatory after ablation. Contrast material-enhanced ultrasonography, computed tomography (CT), and magnetic resonance imaging all may be useful for this assessment. At most institutions, a three-phase contrast-enhanced CT examination is performed immediately or within 1 month after RF ablation to assess the technical success of treatment. If ablation was technically successful, three-phase CT may be repeated at 3-month intervals for evaluation of tumor recurrence. The typical CT finding in the zone subjected to RF ablation is an area of low attenuation that encompasses the tumor and an ablative margin. However, the appearance of the ablative zone may vary greatly, depending on the success of treatment and the time elapsed after the procedure. Ringlike enhancement representing benign reactive hyperemia around the ablation zone, central high-attenuation areas representing greater cellular disruption, and tiny air bubbles frequently are seen at immediate follow-up CT but usually have disappeared by the first or second follow-up examination. The successfully ablated zone gradually involutes. The appearance of the zone differs when residual tumor tissue or local tumor progression is present. Immediate or delayed complications also may be seen at follow-up CT. Radiologists must be familiar with both typical and atypical CT findings and their clinical significance. (c) RSNA, 2008.
Improving gastric accommodation and gastric emptying is an attractive physiological treatment target in patients with functional dyspepsia (FD). We evaluated the effect of DA-9701, a new drug for FD, ...on gastric motor function after a meal in healthy volunteers using magnetic resonance imaging (MRI).
Forty healthy volunteers were randomly allocated to receive either DA-9701 or placebo. After 5 days of treatment, subjects underwent gastric MRI (60 min before and 15, 30, 45, 60, 90, and 120 min after a liquid test meal). Gastric volume was measured through 3-dimensional reconstruction from MRI data. We analyzed 4 outcome variables including changes in total gastric volume (TGV), proximal TGV, and proximal to distal TGV ratio after a meal and gastric emptying rates after adjusting values at the pre-test meal.
Changes in TGV and proximal TGV after a meal did not differ between the DA-9701 and placebo groups (difference between groups -25.9 mL, 95% confidence interval CI -54.0 to 2.3 mL, P = 0.070 and -2.9 mL, 95% CI -30.3 to 24.5 mL, P = 0.832, respectively). However, pre-treatment with DA-9701 increased postprandial proximal to distal TGV ratio more than placebo (difference between groups 0.93, 95% CI 0.08 to 1.79, P = 0.034). In addition, pre-treatment with DA-9701 significantly increased gastric emptying as compared with placebo (mean difference between groups 3.41%, 95% CI 0.54% to 6.29%, P = 0.021, by mixed model for repeated measures).
Our results suggested that DA-9701 enhances gastric emptying and does not significantly affect gastric accommodation in healthy volunteers. Further studies to confirm whether DA-9701 enhances these gastric motor functions in patients with FD are warranted.
ClinicalTrials.gov NCT02091635.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The goal of this study was to estimate the growth rate of hepatocellular carcinoma (HCC) and identify the host factors that significantly affect this rate.
Patients with early-stage HCC (n=175) who ...underwent two or more serial dynamic imaging studies without any anticancer treatment at two tertiary care hospitals in Korea were identified. For each patient, the tumor volume doubling time (TVDT) of HCC was calculated by comparing tumor volumes between serial imaging studies. Clinical and laboratory data were obtained from the medical records of the patients.
The median TVDT was 85.7 days, with a range of 11 to 851.2 days. Multiple linear regression revealed that the initial tumor diameter (a tumor factor) and the etiology of chronic liver disease (a host factor) were significantly associated with the TVDT. The TVDT was shorter when the initial tumor diameter was smaller, and was shorter in HCC related to hepatitis B virus (HBV) infection than in HCC related to hepatitis C virus (HCV) infection (median, 76.8 days vs. 137.2 days; P=0.0234).
The etiology of chronic liver disease is a host factor that may significantly affect the growth rate of early-stage HCC, since HBV-associated HCC grows faster than HCV-associated HCC.
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