Feasibility of Single-Shot Whole Thoracic Time-Resolved MR Angiography to Evaluate Patients with Multiple Pulmonary Arteriovenous Malformations

ObjectiveTo evaluate the feasibility of single-shot whole thoracic time-resolved MR angiography (TR-MRA) to identify the feeding arteries of pulmonary arteriovenous malformations (PAVMs) and reperfusion of the lesion after embolization in patients with multiple PAVMs.Materials and MethodsNine patients (8 females and 1 male; age range, 23–65 years) with a total of 62 PAVMs who underwent percutaneous embolization for multiple PAVMs and were subsequently followed up using TR-MRA and CT obtained within 6 months from each other were retrospectively reviewed. All imaging analyses were performed by two independent readers blinded to clinical information. The visibility of the feeding arteries on maximum intensity projection (MIP) reconstruction and multiplanar reconstruction (MPR) TR-MRA images was evaluated by comparing them to CT as a reference. The accuracy of TR-MRA for diagnosing reperfusion of the PAVM after embolization was assessed in a subgroup with angiographic confirmation. The reliability between the readers in interpreting the TR-MRA results was analyzed using kappa (κ) statistics.ResultsFeeding arteries were visible on the original MIP images of TR-MRA in 82.3% (51/62) and 85.5% (53/62) of readers 1 and 2, respectively. Using the MPR, the rates increased to 93.5% (58/62) and 95.2% (59/62), respectively (κ = 0.760 and 0.792, respectively). Factors for invisibility were the course of feeding arteries in the anteroposterior plane, proximity to large enhancing vessels, adjacency to the chest wall, pulsation of the heart, and small feeding arteries. Thirty-seven PAVMs in five patients had angiographic confirmation of reperfusion status after embolization (32 occlusions and 5 reperfusions). TR-MRA showed 100% (5/5) sensitivity and 100% (32/32, including three cases in which the feeding arteries were not visible on TR-MRA) specificity for both readers.ConclusionSingle-shot whole thoracic TR-MRA with MPR showed good visibility of the feeding arteries of PAVMs and high accuracy in diagnosing reperfusion after embolization. Single-shot whole thoracic TR-MRA may be a feasible method for the follow-up of patients with multiple PAVMs.     

Phenotype of Asthma-COPD Overlap in COPD and Severe Asthma Cohorts

BackgroundAsthma and chronic obstructive pulmonary disease (COPD) are airway diseases with similar clinical manifestations, despite differences in pathophysiology. Asthma-COPD overlap (ACO) is a condition characterized by overlapping clinical features of both diseases. There have been few reports regarding the prevalence of ACO in COPD and severe asthma cohorts. ACO is heterogeneous; patients can be classified on the basis of phenotype differences. This study was performed to analyze the prevalence of ACO in COPD and severe asthma cohorts. In addition, this study compared baseline characteristics among ACO patients according to phenotype.MethodsPatients with COPD were prospectively enrolled into the Korean COPD subgroup study (KOCOSS) cohort. Patients with severe asthma were prospectively enrolled into the Korean Severe Asthma Registry (KoSAR). ACO was defined in accordance with the updated Spanish criteria. In the COPD cohort, ACO was defined as bronchodilator response (BDR) ≥ 15% and ≥ 400 mL from baseline or blood eosinophil count (BEC) ≥ 300 cells/μL. In the severe asthma cohort, ACO was defined as age ≥ 35 years, smoking ≥ 10 pack-years, and post-bronchodilator forced expiratory volume in 1 s/forced vital capacity < 0.7. Patients with ACO were divided into four groups according to smoking history (threshold: 20 pack-years) and BEC (threshold: 300 cells/μL).ResultsThe prevalence of ACO significantly differed between the COPD and severe asthma cohorts (19.8% [365/1,839] vs. 12.5% [104/832], respectively; P < 0.001). The percentage of patients in each group was as follows: group A (light smoker with high BEC) – 9.1%; group B (light smoker with low BEC) – 3.7%; group C (moderate to heavy smoker with high BEC) – 73.8%; and group D (moderate to heavy smoker with low BEC) – 13.4%. Moderate to heavy smoker with high BEC group was oldest, and showed weak BDR response. Age, sex, BDR, comorbidities, and medications significantly differed among the four groups.ConclusionThe prevalence of ACO differed between COPD and severe asthma cohorts. ACO patients can be classified into four phenotype groups, such that each phenotype exhibits distinct characteristics.     

A Retrospective National Study on Colonization Rate and Antimicrobial Susceptibility of Streptococcus agalactiae in Pregnant Korean Women, 2018–2020

PurposeThe prevalence of Group B Streptococcus (GBS) colonization in pregnant Korean women is increasing; however, nationwide studies are lacking. Therefore, we aimed to analyze regional colonization rates and antimicrobial susceptibility for GBS in pregnant Korean women through a nationwide survey.Materials and MethodsFrom January 2018 to December 2020, data from the Seoul Clinical Laboratories on vaginal swab cultures were retrospectively analyzed to detect maternal GBS carriers. Each swab specimen was inoculated onto a 5% blood agar plate and incubated at 35℃–37℃ in a 5% CO₂ incubator for 24 h. GBS isolates were identified using a Microflex MALDI Biotyper. Antimicrobial susceptibility tests were performed using the Vitek 2 automated system.ResultsThe overall nationwide GBS colonization rate in pregnant Korean women was found to be 10.6% (3578/33721). The maternal GBS colonization rates ranged from 10.5%–10.8% over the 3-year study period. The GBS colonization rates by province, in descending order, were as follows: Jeolla-do, 13.2%; Gangwon-do, 12.0%; Chungcheong-do, 11.8%; Gyeonggi-do, 11.3%; Seoul, 10.2%; and Gyeongsang-do, 9.6%. During the study period, the resistance rates against chloramphenicol, levofloxacin, clindamycin, erythromycin, and tetracycline were 2.6%–2.7%, 18.2%–19.6%, 33.4%–35.7%, 35.6%–36.8%, and 50.5%–53.3%, respectively.ConclusionIn pregnant Korean women, GBS colonization rates were in the range of 9.6%–13.2%, with Gyeongsang-do being the lowest and Jeolla-do the highest. The resistance rate against clindamycin was high (33.4%–35.7%). GBS colonization rates during pregnancy should be studied nationwide according to the Centers for Disease Control and Prevention-recommended guidelines with periodic antimicrobial resistance monitoring.     

Methodology in Conventional Head and Neck Reconstruction Following Robotic Cancer Surgery: A Bridgehead Robotic Head and Neck Reconstruction

PurposeRobotic head and neck surgery is widespread nowadays. However, in the reconstruction field, the use of robotic operations is not. This article aimed to examine methodologies for conventional head and neck reconstruction after robotic tumor surgery in an effort to obtain further options for future reconstruction manipulations.Materials and MethodsA retrospective review of all patients who received head and neck robot surgery and conventional reconstructive surgery between October 2016 and September 2021.ResultsIn total, 53 cases were performed. 67.9% of the tumors were greater than 4 cm. Regarding defect size, 47.2% of the lesions were greater than 8 cm. In terms of TNM stage, stage 3 disease was recorded in 26.4% and stage 4 in 52.8%. To make a deep and narrow field wider, we changed the patient’s posture in pre-op field, additional dissection was done. We used radial forearm flap mostly (62.2%).ConclusionConventional head and neck reconstruction after robotic ENT cancer surgery is possible. One key step is to secure additional space in the deep and narrow space left after robotic surgery. For this, we opted for a radial forearm flap mostly. This can be performed as a bridgehead to perform robotic head and neck reconstruction.     

Glial nodule encephalitis in the guinea pig: serial observations following cytomegalovirus infection

Summary Cytomegalovirus (CMV) encephalitis, characterized by microglial nodules, is a major neurological complication in AIDS. There is a clear need for a well-characterized laboratory model of CMV encephalitis. We report here the sequential virological, histopathological, and antibody responses of young guinea pigs inoculated intracerebrally with guinea pig CMV. Virus was found to peak in the brain in the 1st week, to peak in the spleen in the 2nd week, and to be cleared from the brain with the development of serum neutralizing antibody 3 to 4 weeks post infection. Leptomeningitis peaked at the end of the 1st week, independent of the changes found in the parenchyma. Diffuse and focal infiltration of systemic cells was found in the cortex. Microglial nodules consisting of swirled and elongated cells, sometimes in association with intranuclear inclusion bearing cells, were prominent. The parenchymal changes, including scattered foci of ependymitis and ventriculitis, were most prominent in the 2nd week post infection. This model should facilitate studies of the host defense response in the brain and of the role of antiviral therapy in CMV encephalitis.Supported by funds from the Medical Research Service of the Veterans Administration     

Potential pitfalls of magnetic resonance imaging in the diagnosis of avascular necrosis

Magnetic resonance (MR) imaging and radionuclide (RN) bone scans were performed in two patients with collagen vascular disease (CVD) to evaluate hip pains. In both patients RN bone scans demonstrated decreased radioactivity in the femoral heads, whereas, MR imaging was normal. Because early changes of avascular necrosis (AVN) frequently present as decreased radioactivity in the femoral head, special attempts were made to detect this decreased activity using pinhole collimator imaging. The diagnosis of AVN was confirmed surgically by venous pressure measurements. Abnormal RN bone scans representing decreased flow due to vasculitis in patients with CVD, may be more sensitive in the diagnosis of AVN before structural changes can be detected on MR studies.     

Reweighted ℓ1 referenceless PRF shift thermometry

Temperature estimation in proton resonance frequency (PRF) shift MR thermometry requires a reference, or pretreatment, phase image that is subtracted from image phase during thermal treatment to yield a phase difference image proportional to temperature change. Referenceless thermometry methods derive a reference phase image from the treatment image itself by assuming that in the absence of a hot spot, the image phase can be accurately represented in a smooth (usually low order polynomial) basis. By masking the hot spot out of a least squares (?₂) regression, the reference phase image's coefficients on the polynomial basis are estimated and a reference image is derived by evaluating the polynomial inside the hot spot area. Referenceless methods are therefore insensitive to motion and bulk main field shifts, however, currently these methods require user interaction or sophisticated tracking to ensure that the hot spot is masked out of the polynomial regression. This article introduces an approach to reference PRF shift thermometry that uses reweighted ?₁ regression, a form of robust regression, to obtain background phase coefficients without hot spot tracking and masking. The method is compared to conventional referenceless thermometry, and demonstrated experimentally in monitoring HIFU heating in a phantom and canine prostate, as well as in a healthy human liver. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

MR imaging of the alar ligament: morphologic changes during axial rotation of the head in asymptomatic young adults

OBJECTIVE:. The alar ligament plays a critical role in limiting the axial rotation of the head, the left alar ligament being stretched on rotation to the right and vice versa. The purposes of this study were to assess the usefulness of MR imaging in demonstrating the alar ligament and also to identify its morphologic changes during axial rotation of the head in asymptomatic young volunteers. DESIGN AND PATIENTS:. Twenty-two healthy volunteers participated in this study. All subjects underwent four series of contiguous fast spin echo density-weighted MR images with a 2 mm slice thickness including axial and coronal images with the head in neutral position, and coronal images with alternate head rotation to the right and left. The alar ligaments seen on each series of MR images were visually graded 0-2, and grade comparisons were performed between the four series of MR images. We also assessed the morphologic changes of the alar ligament on coronal images during axial rotation of the head. RESULTS:. Grade comparisons for the demonstration of the alar ligament revealed that each of three series of coronal images was statistically significantly better in grade than axial images. During axial rotation of the head, MR images showed rather constant morphologic changes of the alar ligament: elevation and wrapping of the contralateral alar ligament around the dens, associated with slightly upward movement of C1-C2 on that side. This wrap-around effect of the contralateral alar ligament in relation to the dens sometimes caused the apparent shortening of the alar ligament on that side. CONCLUSION:. Reliable assessment of the anatomy and function of the alar ligament can be achieved with MR imaging, preferably in coronal planes. MR imaging with the aid of a functional study may be a valuable imaging modality in the evaluation of alar ligament failure.