Comparison of Virtual Unenhanced Images Derived From Dual-Energy CT With True Unenhanced Images in Evaluation of Gallstone Disease.

OBJECTIVE: The aim of this study was to compare gallstones on virtual unenhanced images and true unenhanced images acquired with dual-energy CT (DECT). MATERIALS AND METHODS: We enrolled 112 patients with right upper quadrant pain and clinically suspected acute cholecystitis or gallstone who underwent DECT--including unenhanced, arterial, and portal phases. Eighty-three gallstones with composition proven by semiquantitative Fourier transform infrared spectroscopy from 45 patients who had undergone cholecystectomy (40 cholesterol gallstones from 21 patients, 43 calcium gallstones from 24 patients) were included. CT images were retrospectively evaluated for stone size, contrast-to-noise ratio (CNR) of gallstone to bile, and visibility and density of gallstones for each image set. The visibility of each type of stone was compared with a paired t test. RESULTS: Both cholesterol and calcium stones measured smaller on virtual unenhanced images than on true unenhanced images, yielding a lower sensitivity of virtual unenhanced images for detecting small gallstones. Mean CNR of cholesterol stones was 2.45 ± 1.32 versus 1.67 ± 1.55 (p < 0.032) and that of calcium stones was 10.59 ± 7.15 and 14.11 ± 9.81 (p < 0.001) for virtual unenhanced and true unenhanced images, respectively. For calcium stones, two readers found 43 of 43 (100%) on true unenhanced images; one reader found 41 of 43 (95%) and the other, 37 of 43 (86%) on virtual unenhanced images. For cholesterol stones, one reader found 20 of 40 (50%) and the other 19 of 40 (47%) on true unenhanced images versus 34 of 40 (85%) and 30 of 40 (75%), respectively, on virtual unenhanced images. The visibility of cholesterol stones was higher on virtual unenhanced images, but that of calcium stones was lower. CONCLUSION: Virtual unenhanced images at DECT allow better visualization of cholesterol gallstones, but true unenhanced images allow better visualization of calcium and small gallstones.

iNOS promotes HBx-induced hepatocellular carcinoma via upregulation of JNK activation.

Inducible nitric oxide (iNOS) is closely correlated with chronic inflammation in hepatitis B virus X protein (HBx)-induced hepatocellular carcinoma (HCC). However, the molecular mechanisms through which iNOS contribute to hepatocarcinogenesis remain poorly understood. Therefore, we investigated the role of iNOS in signaling pathways underlying HBx-induced liver tumorigenesis. iNOS deletion showed a marked decrease in the hepatic tumor size and stage of HBx transgenic (Tg) mice, indicating a strong contribution of iNOS signaling pathways to hepatocarcinogenesis. In addition, we found that nitric oxide (NO) increased HBx mRNA by recruiting CREB to the CRE site of HBV enhancer in HepG2 cells, suggesting a positive feedback loop between HBx and iNOS signaling pathway. Moreover, iNOS-modulated JNK activation was associated with sustained upregulation of Cyclin D1 in HBxTg mice and HepG2-HBx cells. These results imply that iNOS may play a key role in HBx-associated HCC development. Taken together, our findings demonstrate that iNOS aligns with HBx to promote tumor progression. These findings provide a better understating of the mechanism involving HBx-mediated hepatic tumorigenesis and selective inhibition of iNOS may have therapeutic applications in HBx-associated HCC.

Lateral topography for reducing effective dose in low-dose chest CT.

OBJECTIVE: The purposes of this study were to assess radiation exposure during low-dose chest CT by using lateral topography and to compare the lateral topographic findings with findings obtained with anteroposterior topography alone and anteroposterior and lateral topography combined. SUBJECTS AND METHODS: From November 2011 to February 2012, 210 male subjects were enrolled in the study. Age, weight, and height of the men were recorded. All subjects were placed into one of three subgroups based on the type of topographic image obtained: anteroposterior topography, lateral topography, and both anteroposterior and lateral topography. Imaging was performed with a 128-MDCT scanner. CT, except for topography, was the same for all subjects. A radiologist analyzed each image, recorded scan length, checked for any insufficiencies in the FOV, and calculated the effective radiation dose. One-way analysis of variance and multiple comparisons were used to compare the effective radiation exposure and scan length between groups. RESULTS: The mean scan length in the anteroposterior topography group was significantly greater than that of the lateral topography group and the combined anteroposterior and lateral topography group (p < 0.001). The mean effective radiation dose for the lateral topography group (0.735 ± 0.033 mSv) was significantly lower than that for the anteroposterior topography group (0.763 ± 0.038 mSv) and the combined anteroposterior and lateral topography group (0.773 ± 0.038) (p < 0.001). CONCLUSION: Lateral topographic low-dose CT was associated with a lower effective radiation dose and scan length than either anteroposterior topographic low-dose chest CT or low-dose chest CT with both anteroposterior and lateral topograms.

Dual energy CT in patients with acute abdomen; is it possible for virtual non-enhanced images to replace true non-enhanced images?

This study aims to determine whether virtual non-enhanced images derived from dual-energy computed tomography (CT) can replace true non-enhanced images in patients with acute abdomen. Patients with acute abdomen (n = 202) underwent multidetector CT including non-enhanced and contrast-enhanced images obtained at the portal phase using the dual-energy technique. CT attenuation values were measured in abdominal organs. Image quality, noise, artifacts, and acceptability for virtual non-enhanced images compared to true non-enhanced images were rated. Mean sizes of clinically significant stones and mean attenuation values of intraabdominal hemorrhages were compared by means of five-point scales. Effective radiation doses were calculated. Mean CT attenuation values of virtual non-enhanced and true non-enhanced images were similar. Virtual non-enhanced images showed good image quality, mild noise, mild artifacts, and good acceptability compared to true non-enhanced images. A total of 71 clinically significant stones (11 appendicoliths, 33 gallbladder stones, 11 bile duct stones, and 16 urinary stones) and 15 intraabdominal hemorrhages were included in the study. Small stones were detected better on true non-enhanced images than on virtual non-enhanced images. Hemorrhage was similarly detected on both virtual non-enhanced and true non-enhanced images. Mean radiation dose reductions by omitting true non-enhanced images were 33 % in the virtual triple protocol and 47 % in the virtual dual protocol. Image qualities of virtual non-enhanced images are comparable to those of true non-enhanced images. Small stones can be obscured on virtual non-enhanced images. Therefore, tailored application of dual-energy CT is needed for evaluation of patients with acute abdomen.

Lymphangiography and lymphatic embolisation for the treatment of chyle leaks after neck surgery: assessment of lymphangiography findings and embolisation techniques.

OBJECTIVE: To assess lymphangiography findings and outcome of lymphatic embolisation to manage chyle leak after neck surgery. METHODS: Consecutive cases of lymphangiography performed between April 2018 and May 2022 for management of chyle leaks related to neck surgery were retrospectively reviewed. Lymphangiography findings, techniques, and outcomes were analysed. RESULTS: Eight patients (mean age: 46.5 years) were included. Six patients had undergone radical neck dissection for thyroid cancer, and two had undergone lymph node excision. Clinical presentations were: chyle drainage through Jackson Pratt catheters in five patients, lymphorrhea through surgical wounds in two, and enlarging lymphocele in one. Lymphangiography techniques included: inguinal lymphangiography in four patients, retrograde lymphangiography in three, and transcervical lymphangiography in one. Lymphangiography revealed leaks in the terminal thoracic duct in two patients, bronchomediastinal trunk in two, jugular trunk in three, and superficial neck channels in one. Embolisation techniques included: non-selective embolisation of terminal thoracic duct (n = 2), selective embolisation of the jugular trunk (n = 3), selective embolisation of the bronchomediastinal trunk (n = 2), and intranodal glue embolisation of superficial neck channels (n = 1). One patient underwent a repeat procedure. Chyle leak resolved in all patients over a mean of 4.6 days. No complication was encountered. CONCLUSION: Lymphatic embolisation seems to be effective and safe in managing chyle leaks after neck surgery. Lymphangiography allowed for the categorisation of chyle leaks according to their location. Post-embolisation patency of the thoracic duct may be preserved in chyle leaks that do not directly involve the thoracic duct. ADVANCES IN KNOWLEDGE: Lymphatic embolisation is safe and effective in managing chyle leaks after neck surgery. On lymphangiography, the location of contrast media extravasation may not be consistent. The technique for embolisation should be based on the location of the leak. Post-embolisation patency of the thoracic duct may be preserved in chyle leaks that do not directly involve the thoracic duct.

Deviation of Latitude Cut: A Simple Sign to Differentiate Total Hip Arthroplasty from Hemiarthroplasty in Radiography.

This study aims to propose latitude cut deviation for differentiating hip arthroplasty types and evaluate its diagnostic utility in distinguishing total hip arthroplasty (THA) from hemiarthroplasty using radiography. After assessing various cup designs from top manufacturers for THA and hemiarthroplasty, we conducted a retrospective study on 40 patients (20 THA and 20 hemiarthroplasty). Three readers independently evaluated the radiographs, assessing acetabular sparing, cup-bone interface texture, and latitude cut deviation. Diagnostic performance and inter-observer agreement were compared using receiver operating characteristic curves and the Fleiss kappa coefficient. Latitude cut deviation measured on implant designs ranged from 19% to 42% in hemiarthroplasty and from -12% to 9% in THA. The sensitivity, specificity, and accuracy used to distinguish THA from hemiarthroplasty were 60-85%, 55-95%, and 62.5-77.5% for acetabular sparing; 100%, 50-80%, and 75-90% for cup-bone interface texture; and 100%, 90-100%, and 95-100% for latitude cut deviation. Inter-observer agreement for acetabular sparing, cup-bone interface texture, and latitude cut deviation ranged from moderate to excellent (κ = 0.499, 0.772, and 0.900, respectively). The latitude cut deviation exhibited excellent diagnostic performance and inter-reader agreement in distinguishing hemiarthroplasty from THA on radiographs, offering a concise way to identify hip arthroplasty type.

Transient sulcal hyperintensities on fluid-attenuated inversion recovery in migraine with aura: transient sulcal hyperintensities in migraine.

Migraine has been found to be associated with patent foramen ovale. However, in practice, it is difficult to show that microemboli via patent foramen ovale can induce a migraine attack. Our patient showed transient sulcal hyperintensities on fluid-attenuated inversion recovery images during a migraine attack. This supports the hypothesis that microemboli via right-to-left shunt may induce migraine attacks through transient occlusion of microcirculation.

Asymptomatic brain lesions in pilots: a comparative study with non-flying personnel using brain MRI.

INTRODUCTION: As modern aircraft fly at higher altitudes with rapid velocity, pilots have been put in the environment with a possible increasing risk of brain injury and could sustain cumulative brain damage. However, very few studies have investigated brain lesions using MRI in asymptomatic pilots. We evaluated asymptomatic pilots for the presence of cerebral lesions using MRI. METHODS: Enrolled were 31 healthy pilots of the Republic of Korea Air Force (ROKAF) on active flight duty and 31 healthy nonflying ROKAF personnel with ages of or over 45. We checked for the presence of acute and/or chronic medical conditions, smoking habits, alcohol intake, blood pressure, blood tests including lipid panel, glucose, and liver panel, aircraft type, flight hours, flight altitude, and white matter hyperintensities (WMH) on brain MRI. RESULT: The mean age of both groups was 51.2 yr and the mean total flight hours of the pilots was 3025.0 h. There was no statistical difference between the pilots and non-flying personnel for WMH findings (54.8%/ vs. 32.3%). Of the factors related to flight, only the flying altitude (OR 1.005) was significantly related to the presence of WMH on multivariate analysis. Glucose levels and cholesterol levels were also related to WMH. DISCUSSION: Despite our negative results, there could be the possibility of cumulative brain damage in asymptomatic pilots considering the positive effect of altitude and the positive trend of pilots for the presence of WMH. Additional investigations are surely needed.

Low-dose chest computed tomography as a screening tool: findings in 536 aircrews.

BACKGROUND: Plain chest radiographs and pulmonary function tests have been used for pulmonary screening for flight duties of aircrews of the Republic of Korea Air Force. However, the screening accuracy of plain chest radiographs is controversial. Chest CT imaging with low-dose protocol (LDCT) improves detection of intra-thoracic abnormalities compared to plain chest radiographs. The aim of this study was to assess the influence of LDCT on flight duties of aircrews and to investigate their radiologic findings. METHODS: From June 2009 to May 2011, the Aerospace Medical Center screened asymptomatic subjects 40 yr of age or older to evaluate intra-thoracic abnormalities using LDCT. The abnormal findings, including types and frequency, were recorded and the aircrew's flight duties were also recorded. RESULTS: This study included 536 subjects. No abnormal findings were found in 387 (72.2%) subjects. Abnormal findings related to pulmonary nodules were detected in 123 (23.00%) subjects. Air-trapping lesions were found in 33 (6.1%) subjects. One subject had a mediastinal tumor. Changes of flight duty were made in 26 (4.9%) subjects on the basis of LDCT findings. No subject was permanently disqualified for flight duty. CONCLUSIONS: Pulmonary screening with LDCT could detect many intra-thoracic abnormalities. LDCT was especially useful in the detection of bullae and bleb, and the flight duties of all subjects with bullae and bleb were changed.

Doppler ultrasonography measurement of hepatic hemodynamics during Valsalva maneuver: healthy volunteer study.

PURPOSE: The aim of our study was to assess the hemodynamic change of liver during the Valsalva maneuver using Doppler ultrasonography. METHODS: Thirty healthy men volunteers were enrolled (mean age, 25.5±3.64 years). The diameter, minimal and maximal velocities, and volume flow of intrahepatic inferior vena cava (IVC), middle hepatic vein (MHV), and right main portal vein (RMPV) was measured during both rest and Valsalva maneuver. These changes were compared using paired t-test. RESULTS: The mean diameters (cm) of the intrahepatic IVC at rest and Valsalva maneuver were 1.94±0.40 versus 0.56±0.66 (P<0.001). The mean diameter (cm), minimal velocity (cm/sec), maximal velocity (cm/sec), and volume flow (mL/min) of MHV at rest and Valsalva maneuver were 0.60±0.15 versus 0.38±0.20 (P<0.001), -7.98±5.47 versus 25.74±13.13 (P<0.001), 21.34±6.89 versus 35.12±19.95 (P=0.002), and 106.94±97.65 versus 153.90±151.80 (P=0.014), respectively. Those of RMPV at rest and Valsalva maneuver were 0.78±0.21 versus 0.76±0.20 (P=0.485), 20.21±8.22 versus 18.73±7.43 (P=0.351), 26.79±8.85 versus 24.93±9.91 (P=0.275), and 391.52±265.63 versus 378.43±239.36 (P=0.315), respectively. CONCLUSION: The blood flow velocity and volume flow of MHV increased significantly during Valsalva maneuver. These findings suggest that hepatic vein might play an important role to maintain venous return to the heart during the maneuver.

Clinical implications of T-wave inversion in an asymptomatic population undergoing annual medical screening (from the Korean Air Forces Electrocardiogram Screening).

This study aimed to determine prevalence, differentiate underlying causes, and identify the benign group in subjects with asymptomatic T-wave inversion (TWI). We retrospectively read 12-lead electrocardiograms from 3,929 consecutive asymptomatic men in the air force (3,929 participants, mean age 39.3 ± 8.7 years) who underwent medical screening at the Aerospace Medical Center, Korea, from September 2010 to August 2012. TWIs other than in right precordial leads (V1 and V2) were present in 23 men (0.6%). All subjects with persistent TWI for 1 year (n = 18) underwent additional study, with the exception of 1 patient who refused further evaluation. Of 17 subjects with investigated persistent TWI, 8 (47.1%) had an apically displaced papillary muscle, 5 (29.4%) exhibited idiopathic TWI, 3 (17.6%) had apical hypertrophic cardiomyopathy, and 1 (5.9%) had Maron type 2 hypertrophic cardiomyopathy with dynamic left ventricular outflow obstruction. The depth of TWI was significantly shallow in the benign group (idiopathic TWI, 1.6 ± 0.5 mm) compared with potentially nonbenign group (the others; 5.5 ± 3.3 mm, p = 0.021). Lateral lead TWI was significantly correlated with potentially nonbenign group (46% vs 0%, p = 0.049). In conclusion, asymptomatic TWI is not rare (0.6%), even in a healthy population such as Korean Air Force society, and at least 29.4% of subjects with TWI are considered to belong to the benign group that does not require aggressive evaluation and criteria of TWI ≤2 mm other than lateral leads without co-morbidity could help to distinguish the benign group from the potentially nonbenign group.

Gd-EOB-DTPA enhanced micro-MR imaging of hepatic tumors in H-ras 12V transgenic mice.

RATIONALE AND OBJECTIVES: The aims of this study were to evaluate the morphologic characteristics and growth pattern of hepatic tumors in H-ras 12V transgenic (TG) mice using a micro-magnetic resonance (MR) system and to assess the usefulness of gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) enhancement for the detection of hepatic tumors in these mice. MATERIALS AND METHODS: Hepatocellular carcinoma lines were established to allow insertion of the H-ras 12V transgene under the control of the albumin enhancer/promoter. Seven H-ras 12V TG mice and four wild-type mice were included in this study. The mice underwent various MR imaging examinations, including T1-weighted imaging (repetition time, 300 ms; echo time, 11 ms), Gd-EOB-DTPA-enhanced T1-weighted imaging (dose, 0.025 mmol/kg), and T2-weighted imaging (repetition time, 3500 ms; echo time, 36 ms), with a 4.7-T MR scanner, at 4, 6, 8, and 9 months of age. All mice were euthanized after the final MR imaging procedure, except for one TG mouse and two wild-type mice that were euthanized after MR imaging procedures at 4 months of age. For imaging analysis, the tumor characteristics in each MR sequence, including tumor size, number, and signal intensity (SI), were recorded, and the contrast-to-noise ratio and contrast enhancement ratio were calculated to quantify the SI of the tumor. The MR images were correlated with the findings of histopathologic examinations. RESULTS: No tumors were detected in the four wild-type mice. In the six TG mice, a total of 67 tumors were found in histopathologic specimens obtained at 9 months of age. Of the 67 tumors, 62 were detected on Gd-EOB-DTPA-enhanced T1-weighted images with fat saturation. The majority of hepatic tumors showed high SI on T1-weighted images without fat saturation. The SI diminished on T1-weighted images with fat saturation. The tumor contrast-to-noise ratio for Gd-EOB-DTPA-enhanced T1-weighted imaging was significantly better than that for the other sequences. The tumors were histopathologically confirmed as hepatocellular adenomas (n = 32) and well-differentiated hepatocellular carcinomas (n = 35). CONCLUSIONS: Micro-MR imaging can reveal the characteristics of hepatic tumors in a live murine model. Gd-EOB-DTPA-enhanced T1-weighted imaging is helpful in the detection of hepatic tumors in H-ras 12V TG mice.