Hun-Kyu Ryeom

Brain activation patterns of motor imagery reflect plastic changes associated with intensive shooting training

Evidence from previous studies has suggested that motor imagery and motor action engage overlapping brain systems. As a result of this observation that motor imagery can activate brain regions associated with actual motor movement, motor imagery is expected to enhance motor skill performance and become an underlying principle for physical training in sports and physical rehabilitation. However, few studies have examined the effects of physical training on motor imagery in beginners. Also, differences in neural networks related to motor imagery before and after training have seldom been studied. In the current study, using functional magnetic resonance imaging (fMRI), we investigated the question of whether motor imagery can reflect plastic changes of neural correlates associated with intensive training. In fact, motor imagery was used in this study as a tool to assess the brain areas involved in shooting and involved in learning of shooting. We discovered that use of motor imagery resulted in recruitment of widely distributed common cortical areas, which were suggested to play a role in generation and maintenance of mental images before and after 90 h of shooting training. In addition to these common areas, brain activation before and after 90 h of shooting practice showed regionally distinct patterns of activity change in subcortical motor areas. That is, basal ganglia showed increased activity after 90 h of shooting practice, suggesting the occurrence of plastic change in association with gains in performance and reinforcement learning. Therefore, our results suggest that, in order to reach a level of expertise, the brain would change through initial reinforcement of preexistent connections during the training period and then use more focused neural correlates through formation of new connections.

The optimization of scan timing for contrast-enhanced magnetic resonance angiography.

Objective To determine the optimal scan timing for contrast-enhanced magnetic resonance angiography and to evaluate a new timing method based on the arteriovenous circulation time. Materials and Methods Eighty-nine contrast-enhanced magnetic resonance angiographic examinations were performed mainly in the extremities. A 1.5T scanner with a 3-D turbo-FLASH sequence was used, and during each study, two consecutive arterial phases and one venous phase were acquired. Scan delay time was calculated from the time-intensity curve by the traditional (n = 48) and/or the new (n = 41) method. This latter was based on arteriovenous circulation time rather than peak arterial enhancement time, as used in the traditional method. The numbers of first-phase images showing a properly enhanced arterial phase were compared between the two methods. Results Mean scan delay time was 5.4 sec longer with the new method than with the traditional. Properly enhanced first-phase images were found in 65% of cases (31/48) using the traditional timing method, and 95% (39/41) using the new method. When cases in which there was mismatch between the target vessel and the time-intensity curve acquisition site are excluded, erroneous acquisition occurred in seven cases with the traditional method, but in none with the new method. Conclusion The calculation of scan delay time on the basis of arteriovenous circulation time provides better timing for arterial phase acquisition than the traditional method.

Long-term outcomes of surgery alone versus surgery following preoperative chemoradiotherapy for early T3 rectal cancer A propensity score analysis

Abstract Recently, a few studies have raised the question of whether preoperative chemoradiotherapy (PCRT) is essential for all T3 rectal cancers. This case-matched study aimed to compare the long-term outcomes of surgery alone with those of PCRT + surgery for magnetic resonance imaging (MRI)-assessed T3ab (extramural depth of invasion ⩽5 mm) and absent mesorectal fascia invasion (clear MRF) in mid/lower rectal cancer patients. From January 2006 to November 2012, 203 patients who underwent curative surgery alone (n = 118) or PCRT + surgery (n = 85) were enrolled in this retrospective study. A 1:1 propensity score-matched analysis was performed to eliminate the inherent bias. Case-matching covariates included age, sex, body mass index, histologic grade, carcinoembryonic antigen, operation method, follow-up period, tumor height, and status of lymph node metastasis. The end-points were the 5-year local recurrence (LR) rate and disease-free-survival (DFS). After propensity score matching, 140 patients in 70 pairs were included. Neither the 5-year LR rate nor the DFS was significantly different between the 2 groups (the 5-year LR rate, P = 0.93; the 5-year DFS, P = 0.94). The 5-year LR rate of the surgery alone was 2% (95% confidence interval [CI] 0.2%–10.9%) versus 2% (95% CI 0.2%–10.1%) in the PCRT + surgery group. The 5-year DFS of the surgery alone was 87% (95% CI 74.6%–93.7%) versus 88% (95% CI 77.8%–93.9%) in the PCRT + surgery group. In patients with MRI-assessed T3ab and clear MRF mid/lower rectal cancer, the long-term outcomes of surgery alone were comparable with those of the PCRT + surgery. The suggested MRI-assessed T3ab and clear MRF can be used as a highly selective indication of surgery alone in mid/lower T3 rectal cancer. Additionally, in those patients, surgery alone can be tailored to the clinical situation.

Intrahepatic Artery Pseudoaneurysm-induced Hemobilia Caused by a Plastic Biliary Stent After ABO-incompatible Living-donor Liver Transplantation: A Case Report

Bile leakage after duct-to-duct anastomosis in living-donor liver transplantation (LDLT) can mostly be managed by therapeutic endoscopic retrograde cholangiopancreatography. Following this, various complications such as biliary infection, pancreatitis, perforation, and bleeding can occur, and endoscopic sphincterotomy is primarily associated with post- endoscopic retrograde cholangiopancreatography bleeding; other causes have been published in case reports. In the present case, a plastic biliary stent used for treating liver abscesses and leakage at the bile duct anastomosis site after ABO-incompatible LDLT resulted in an intrahepatic artery pseudoaneurysm and hemobilia, which were managed by angiography and coil embolization. Although the complex postoperative course after LDLT can obscure the prompt diagnosis of an intrahepatic artery pseudoaneurysm and hemobilia, biliary stenting should be considered as a possible cause.

Lead-Induced Impairments in the Neural Processes Related to Working Memory Function

Background It is well known that lead exposure induces neurotoxic effects, which can result in a variety of neurocognitive dysfunction. Especially, occupational lead exposures in adults are associated with decreases in cognitive performance including working memory. Despite recent advances in human neuroimaging techniques, the neural correlates of lead-exposed cognitive impairment remain unclear. Therefore, this study was aimed to compare the neural activations in relation to working memory function between the lead-exposed subjects and healthy controls. Methodology/Principal Findings Thirty-one lead-exposed subjects and 34 healthy subjects performed an n-back memory task during MRI scan. We performed fMRI using the 1-back and 2-back memory tasks differing in cognitive demand. Functional MRI data were analyzed using within- and between-group analysis. We found that the lead-exposed subjects showed poorer working memory performance during high memory loading task than the healthy subjects. In addition, between-group analyses revealed that the lead-exposed subjects showed reduced activation in the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, pre supplementary motor areas, and inferior parietal cortex. Conclusions/Significance Our findings suggest that functional abnormalities in the frontoparietal working memory network might contribute to impairments in maintenance and manipulation of working memory in the lead-exposed subjects.

Gadolinium Complex of 1,4,7,10-Tetraazacyclododecane-1,4,7-trisacetic Acid (DO3A)–Ethoxybenzyl (EOB) Conjugate as a New Macrocyclic Hepatobiliary MRI Contrast Agent

We report the synthesis of a macrocyclic Gd chelate based on a 1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid (DO3A) coordinationn cage bearing an ethoxybenzyl (EOB) moiety and discuss its use as a T1 hepatobiliary magnetic resonance imaging (MRI) contrast agent. The new macrocyclic liver agent shows high chelation stability and high r1 relaxivity compared with linear-type Gd chelates, which are the current clinically approved liver agents. Our macrocyclic, liver-specific Gd chelate was evaluated in vivo through biodistribution analysis and liver MRI, which demonstrated its high tumor detection sensitivity and suggested that the new Gd complex is a promising contrast agent for liver cancer imaging.

Long-term follow-up of large symptomatic hepatic cysts treated by percutaneous ethanol sclerotherapy

Background As a minimally invasive treatment, ethanol sclerotherapy has been used for large symptomatic hepatic cysts, but there are not many long-term reports on treatment outcomes and safety. Purpose To evaluate the long-term outcomes of percutaneous ethanol sclerotherapy in patients with large symptomatic hepatic cysts. Material and Methods This study included 43 symptomatic, enlarging hepatic cysts in 42 patients who had undergone ethanol sclerotherapy from 2003 to 2013 and were followed up for >1 year. The treatment outcomes were evaluated in terms of the reduction of cyst size and resolution of symptoms. The patients were followed up for a mean period of 33 months with either ultrasound or computed tomography examination. Results Thirty-nine hepatic cysts (91%) were successfully treated with ethanol sclerotherapy, showing resolution of symptoms and remarkable reduction in cyst volume. Eight hepatic cysts (19%) disappeared completely, and 31 hepatic cysts (72%) decreased in size during the follow-up period. The mean diameter of the cysts decreased from 12.5 ± 4.4 cm to 3.8 ± 3.4 cm during follow-up. There were no immediate serious complications related to the procedure. There were four cases (9%) of treatment failure requiring subsequent surgical procedures. Conclusion Percutaneous ethanol sclerotherapy can be considered as an effective first-line treatment for large symptomatic hepatic cysts.

Invasive Breast Cancer: Prognostic Value of Peritumoral Edema Identified at Preoperative MR Imaging

Purpose To determine the prognostic value of peritumoral edema identified at preoperative breast magnetic resonance (MR) imaging for disease recurrence in patients with invasive breast cancer. Materials and Methods Between January 2011 and December 2012, 353 women (median age, 49 years; range, 27-77 years) with invasive breast cancer who had undergone preoperative MR imaging and mastectomy or breast-conserving surgery were identified. Two radiologists independently reviewed peritumoral edema on the basis of the degree of the signal intensity surrounding the tumor on T2-weighted images. The association of disease recurrence with peritumoral edema and clinical-pathologic features was assessed by using the multivariate Cox proportional hazards model and the integrated discrimination improvement (IDI) and continuous net reclassification improvement (NRI) indexes. Results Twenty-four patients (6.8%) had disease recurrence after 27.2 months of median follow-up. At multivariate analysis, higher N stage (hazard ratio = 4.84, P = .002) and the presence of lymphovascular invasion (hazard ratio = 2.48, P = .044) and peritumoral edema (hazard ratio = 2.77, P = .022) were independent factors associated with disease recurrence. IDI and continuous NRI showed significant improvement in the accuracy of the association with disease recurrence when peritumoral edema was added to established clinical-pathologic features (IDI = 0.061, P < .001; continuous NRI = 0.334, P = .012). Conclusion Peritumoral edema identified at preoperative MR imaging is independently associated with disease recurrence. Peritumoral edema assessment may provide better prognostication in patients with invasive breast cancer.