Seung Hyoung Kim

Evaluation of the Somatotopic Organization of Corticospinal Tracts in the Internal Capsule and Cerebral Peduncle: Results of Diffusion-Tensor MR Tractography

Objective We have used diffusion tensor tractography (DTT) for the evaluation of the somatotopic organization of corticospinal tracts (CSTs) in the posterior limb of the internal capsule (PLIC) and cerebral peduncle (CP). Materials and Methods We imaged the brains of nine healthy right-handed subjects. We used a spin-echo echo-planar imaging (EPI) sequence with 12 diffusion-sensitized directions. DTT was calculated with an angular threshold of 35 degrees and a fractional anistropy (FA) threshold of 0.25. We determined the location of the CSTs by using two regions of interest (ROI) at expected areas of the pons and expected areas of the lateral half of the PLIC, in the left hemisphere of the brain. Fiber tracts crossing these two ROIs and the precentral gyrus (PCG) were defined as CSTs. Four new ROIs were then defined for the PCG, from the medial to lateral direction, as ROI 1 (medial) to ROI 4 (lateral). Finally, we defined each fiber tract of the CSTs between the pons and each ROI in the PCG by using two ROIs methods. Results In all subjects, the CSTs were organized along the long axis of the PLIC, and the hand fibers were located anterior to the foot fibers. The CSTs showed transverse orientation in the CP, and the hand fibers were located usually medial to the foot fibers. Conclusion Corticospinal tracts are organized along the long axis of the PLIC and the horizontal direction of the CP.

Comparison of Three Free-Breathing T2-Weighted MRI Sequences in the Evaluation of Focal Liver Lesions

OBJECTIVE The purpose of this study was to compare three free-breathing T2-weighted MRI sequences in the evaluation of focal liver lesions. MATERIALS AND METHODS Forty-nine patients with 86 focal liver lesions (56 malignant, 30 benign) underwent liver MRI with free-breathing sequences: turbo spin-echo (TSE) with navigator-triggered prospective acquisition correction (PACE), respiration-triggered TSE, and HASTE with navigator-triggered PACE. The images were retrospectively reviewed by two independent observers. Diagnostic performance was evaluated with receiver operating characteristics and sensitivity. The images were assessed quantitatively by measurement of the liver signal-to-noise ratio (SNR) and the lesion-to-liver contrast-to-noise ratio (CNR). RESULTS The PACE TSE sequence had better receiver operating characteristic curves for lesion detection and characterization than did the respiration-triggered TSE sequence, but the difference was not statistically significant (p > 0.05). The PACE TSE sequence had a significantly greater area under the curve for lesion detection (p < 0.01) and lesion characterization (p < 0.001) than did the PACE HASTE sequence. The composite sensitivity of the PACE TSE sequence for lesion detection was significantly higher than that of respiration-triggered TSE (p < 0.05) and PACE HASTE (p < 0.01). The mean signal-to-noise ratio for liver and the contrast-to-noise ratio for hepatic lesions were higher with the PACE HASTE than with the other sequences. CONCLUSION The navigator-triggered PACE technique is a valid method for T2-weighted MRI of the liver and may replace conventional respiration-triggered techniques.

Fluoroscopically guided placement of self-expandable metallic stents and stent-grafts in the treatment of acute malignant colorectal obstruction.

PURPOSE To evaluate the technical feasibility and clinical effectiveness of fluoroscopically guided placement of self-expandable metallic stents and stent-grafts for acute malignant colorectal obstruction. MATERIALS AND METHODS Radiologic images and clinical reports of 42 patients (22 men, 20 women; age range, 28-93 years; median age, 65.5 years) who underwent fluoroscopically guided colorectal stent insertion without endoscopic assistance for acute malignant obstruction were reviewed retrospectively. Eighteen patients received bare stents as a bridge to surgery. Twenty-four patients received 27 insertions of either a bare stent (n = 15) or a stent-graft (n = 12) for palliation. The obstruction was located in the rectum (n = 8), sigmoid (n = 17), descending colon (n = 8), splenic flexure (n = 3), and transverse colon (n = 6). RESULTS Clinical success, defined as more than 50% dilatation of the stent with subsequent symptomatic improvement, was achieved in 41 of the 42 patients (98%). No major procedure-related complications occurred. Minor complications occurred in eight of the 45 procedures (18%). No perioperative mortalities occurred within 1 month after surgery. In the palliative group, the median stent patency was 62 days (range, 0-1,014 days). There was no statistically significant difference in stent patency between the bare stents (range, 0-855 days; median, 68 days) and stent-grafts (range, 1-1,014 days; median, 81 days). CONCLUSIONS Fluoroscopically guided placement of self-expandable metallic stents and stent-grafts for the relief of acute malignant colorectal obstruction was technically feasible without endoscopic assistance-even in lesions proximal to the splenic flexure and transverse colon-and clinically effective in both bridge to surgery and palliative management.

Imaging of Intracranial Plaques with Black‐Blood Double Inversion Recovery MR Imaging and CT

We evaluated the feasibility of black‐blood double inversion recovery magnetic resonance imaging (BBDIR) and CT imaging (CTI) for depiction of IAPs.

Distinction of reactive joint fluid from pyogenic abscess by diffusion-weighted imaging.

It is difficult to distinguish reactive joint fluid from infectious joint fluid by conventional MR images. In this presented case, we successfully distinguished these two conditions using diffusion‐weighted imaging. J. Magn. Reson. Imaging 2007.

Preoperative N Staging of Gastric Cancer by Stomach Protocol Computed Tomography

Purpose Clinical stage of gastric cancer is currently assessed by computed tomography. Accurate clinical staging is important for the tailoring of therapy. This study evaluated the accuracy of clinical N staging using stomach protocol computed tomography. Materials and Methods Between March 2004 and November 2012, 171 patients with gastric cancer underwent preoperative stomach protocol computed tomography (Jeju National University Hospital; Jeju, Korea). Their demographic and clinical characteristics were reviewed retrospectively. Two radiologists evaluated cN staging using axial and coronal computed tomography images, and cN stage was matched with pathologic results. The diagnostic accuracy of stomach protocol computed tomography for clinical N staging and clinical characteristics associated with diagnostic accuracy were evaluated. Results The overall accuracy of stomach protocol computed tomography for cN staging was 63.2%. Computed tomography images of slice thickness 3.0 mm had a sensitivity of 60.0%; a specificity of 89.6%; an accuracy of 78.4%; and a positive predictive value of 78.0% in detecting lymph node metastases. Underestimation of cN stage was associated with larger tumor size (P<0.001), undifferentiated type (P=0.003), diffuse type (P=0.020), more advanced pathologic stage (P<0.001), and larger numbers of harvested and metastatic lymph nodes (P<0.001 each). Tumor differentiation was an independent factor affecting underestimation by computed tomography (P=0.045). Conclusions Computed tomography with a size criterion of 8 mm is highly specific but relatively insensitive in detecting nodal metastases. Physicians should keep in mind that computed tomography may not be an appropriate tool to detect nodal metastases for choosing appropriate treatment.

Diagnostic Value of Clinical T Staging Assessed by Endoscopy and Stomach Protocol Computed Tomography in Gastric Cancer: The Experience of a Low-Volume Institute

Purpose Clinical staging of gastric cancer appears to be important more and more for tailored therapy. This study aimed to verify the accuracy of clinical T staging in a low-volume institute. Materials and Methods We retrospectively reviewed prospectively collected data of gastric cancer patients who underwent resection. A total of 268 patients of gastric cancer were enrolled from March 2004 to June 2012. These demographics, tumor characteristics, and clinical stages were analyzed for identification of diagnostic value of clinical T staging. Results The predictive values for pT1 of endoscopy and computed tomography were 90.0% and 89.4%, respectively. In detail, the predictive values of endoscopy for pT1a, pT1b, and pT2 or more were 87%, 58.5%, and 90.6%, respectively. The predictive values of computed tomography for pT1a, pT1b, and pT2 or more were 68.8%, 73.9%, and 84.4%, respectively. The factors leading to underestimation of pT2 or more lesions by gastroscopy were the middle third location, the size greater than 2 cm, and younger age. Those for overestimation of pT1 lesion by computed tomography were male, age more than 70 years, elevated type, and size greater than 3 cm. Conclusions Diagnostic accuracy of early gastric cancer was 90%, which is comparable to those of high volume center. In patients with early gastric cancer, limited gastrectomy or minimal invasive surgery can be safely introduced at a low volume center also. However, the surgeon of low-volume institute should consider the accuracy of clinical staging before extending the indication of limited treatment.

Usefulness of contrast enhanced FLAIR imaging for predicting the severity of meningitis

The aim of this study was to evaluate whether contrast enhanced fluid attenuated inversion recovery (CE-FLAIR) imaging can be used to predict the severity of meningitis based on leptomeningeal enhancement (LE) score and cerebrospinal fluid signal intensity (CSF-SI) on CE-FLAIR. We retrospectively analyzed data collected from 43 consecutive patients admitted to our hospital due to meningitis. Clinical factors including initial Glasgow Coma Scale (GCS) score, CSF glucose ratio, log CSF protein, log CSF WBC, and prognosis were evaluated. The LE score was semi-quantitatively scored, and we evaluated CSF-SI ratio at the interpeduncular or quadrigerminal cisterns on CE-FLAIR. We evaluated the differences in clinical variables, LE scores and CSF-SI ratios between the recovery and the complication group. We assessed the correlation between clinical variables, LE scores and CSF-SI ratios. The values of log CSF protein, CSF-SI ratio, and LE score were significantly higher in the complication group (p value <0.05). GCS score and CSF glucose ratio were significantly lower in the complication group (p value <0.01). The LE scores had significant negative correlation with GCS scores and CSF glucose ratios (p value <0.001). The LE score was significantly positively correlated with the value of log CSF protein and CSF-SI ratio (p value <0.01). The CSF-SI ratio was negatively correlated with GCS score and CSF glucose ratio (p value <0.01). The CSF-SI ratio was positively correlated with the value of log CSF protein (p value <0.05). Our results suggest that LE score and CSF-SI ratio are well correlated with clinical prognostic factors. We may predict the clinical severity of meningitis by using LE scores and CSF-SI ration on CE-FLAIR imaging.

Outcomes of Patients with Elevated α-Fetoprotein Level and Initial Negative Findings at MR Imaging

PURPOSE To evaluate interval cancer diagnosis in patients with elevated α-fetoprotein (AFP) level and initial negative findings at magnetic resonance (MR) imaging. MATERIALS AND METHODS The institutional review board approved this HIPAA-compliant retrospective study and waived informed consent. Seventeen patients with elevated AFP levels (>300 ng/mL [>300 μg/L]) and initial negative findings at hepatic MR imaging from 2002 to 2011 were identified. MR reports, pathology reports, and medical records were reviewed to determine outcome, including identification of hepatocellular carcinoma (HCC), and track changes in serum AFP level. Initial and follow-up MR images were reviewed to evaluate presence and size of hepatic nodules. Significance of AFP values was tested with repeated-measures analysis of variance. RESULTS Ten (59%) of 17 patients developed HCCs (13 tumors) after a mean of 138 days (range, 41-247 days). Nine (90%) of 10 patients with HCCs underwent follow-up MR imaging, and one patient (10%) underwent liver transplantation without MR follow-up. Of 12 HCCs in nine patients who underwent follow-up MR imaging, 10 (83%) were noted at follow-up MR imaging and two were found only at surgery. Mean diameter of visualized HCCs was 3.4 cm. Of 10 HCCs detected at follow-up MR imaging, five were identifiable in retrospect at initial MR studies (mean diameter, 1.4 cm). Serum AFP levels in patients with HCCs were significantly higher than those in patients without HCCs and progressively increased over time (P = .012). CONCLUSION Subsequent HCCs in patients with elevated AFP levels and initial negative findings at MR imaging are relatively common and demonstrable during short follow-up. Close follow-up (serial 3-month studies) is recommended in the setting of a steady increase in AFP level.

The Efficacy of Primary Interventional Urethral Realignment for the Treatment of Traumatic Urethral Injuries

PURPOSE To evaluate the efficacy of primary interventional urethral realignment (PIUR) in patients with traumatic urethral injuries. MATERIALS AND METHODS This retrospective study included 13 patients with traumatic urethral injuries who were treated with PIUR between September 2008 and February 2014. All 13 patients were men with the mean age of 56.3 years. Technical success rate of PIUR, time to PIUR, required procedure time, length of hospital stay, duration of urethral catheterization, and complications after PIUR were investigated. RESULTS PIUR was technically successful in 12 of 13 patients (92.3%). The mean time from trauma to PIUR was 44 hours (range, 1-240 h). The mean procedure time was 20.2 minutes (range, 3-90 min). The median length of hospital stay was 15 days (range, 1-60 d). The mean duration of urethral catheterization after PIUR was 25 days (range, 9-65 d). There were no immediate complications related to PIUR, although 6 of 12 patients developed symptomatic urethral stricture after PIUR. The mean time to stricture development after PIUR was 4.3 months (range, 2-12 mo). Of the 6 patients, 2 were treated with endoscopic internal urethrotomy, and 4 were treated with interventional radiologic urethral balloon dilation. CONCLUSIONS PIUR can be safe and effective for patients with traumatic urethral injuries. However, symptomatic stricture formation occurred in one-half of the successful realignment procedures.