Etiology and Clinical Characteristics of Community-Acquired Pneumonia in Korean Children During the PreCOVID-19 Period, 2015-2020

Background@#There have been many epidemiologic studies on community-acquired pneumonia (CAP) among children, most of which had substantial limitations. This study investigated the etiologic distribution and clinical characteristics of CAP in Korean children for 5 years before the coronavirus disease 2019 (COVID-19) pandemic. @*Methods@#A retrospective analysis of children hospitalized for CAP at 4 referral hospitals during 2015-2020 was performed. Cases in which bronchiolitis was suspected or pulmonary infiltration was not evident on chest radiography (CXR) were excluded. Viruses and atypical bacteria were defined as detected when positive in the polymerase chain reaction test performed for respiratory specimens. Serologic testing result for Mycoplasma pneumoniae was incorporated with strict interpretation. Pyogenic bacteria were included only when cultured in blood, pleural fluid, or bronchoalveolar lavage, but those cultured in endotracheal aspirate or sputum when the case was clinically evident bacterial pneumonia were also included. @*Results@#A total of 2,864 cases of suspected pneumonia were selected by diagnosis code and CXR findings. Medical chart and CXR review excluded nosocomial pneumonia and cases without evident infiltration, resulting in 517 (18.1%) CAP cases among 489 children.Regarding clinical symptoms, high fever was present in 59.4% and dyspnea in 19.9% of cases.Respiratory support was required for 29.2% of patients, including mechanical ventilation for 3.9%. Pathogens were detected in 49.9% of cases, with viruses in 32.3%, atypical bacteria in 17.8%, and pyogenic bacteria in 2.3% of cases. As single pathogens, M. pneumoniae (16.8%) and respiratory syncytial virus (RSV, 13.7%) were the most common. Parenteral β-lactam and macrolide antibiotics were administered in 81.6% and 50.7% of cases, respectively. A total of 12 (2.3%) cases resulted in poor outcomes, including 3 deaths. @*Conclusion@#M. pneumoniae and RSV were the most commonly detected pathogens of pediatric CAP, which was selected by strict clinical and radiologic criteria. It is necessary to carefully decide whether to use parenteral antibiotics based on the epidemiology and clinical features of CAP in children.

Rare Form of Schwannoma as a Purely Hemorrhagic Cystic Tumor Located in an Intermuscular Plane

Schwannomas are mostly solid tumors, some of which may contain cystic degenerations or hemorrhages. However, a schwannoma seen as a purely hemorrhagic cystic tumor is very rare. A 63-year-old woman was referred to the hospital due to a slow-growing mass (present for about 5 years) on her right thigh. She complained about vague pain but without neurologic symptoms such as numbness or tingling sensations. MR images showed an oval lesion with defined margins surrounded by the rectus femoris, vastus lateral, and the vastus intermedius. It was characterized as a multilocular cystic lesion composed of hemorrhagic fluid. In addition, the benign hemorrhagic cystic lesion was differentially diagnosed by radiological techniques as a hemorrhagic ganglion cyst. The lesion was surgically excised and, based on pathological features, was diagnosed as being a schwannoma. We report a purely hemorrhagic cystic schwannoma located in an intermuscular plane.

Rare Form of Rheumatoid Nodule around Ischial Tuberosity Mimicking Ischiogluteal Bursitis

We are reporting about a case of a rheumatoid nodule, beneath the ischial tuberosity, mimicking ischiogluteal bursitis. Rheumatoid nodules are frequently seen, at the subcutaneous soft tissues of repetitive mechanical irritation points, and prominent bones. There have been no reported cases of rheumatoid nodules, extending just beneath the ischial tuberosity bone. A 68-year-old woman with a seven-year history of rheumatoid arthritis, suffered for six months, from right buttock swelling and discomfort in seating. A cystic lesion postero-inferior to the ischial tuberosity, was noted in the MRI scan, which was thought to be ischiogluteal bursitis, because of its characteristic location and appearance. Histopathologic analysis and gross findings on the operation, revealed no evidence of bursitis.

Rare Form of Rheumatoid Nodule around Ischial Tuberosity Mimicking Ischiogluteal Bursitis

We are reporting about a case of a rheumatoid nodule, beneath the ischial tuberosity, mimicking ischiogluteal bursitis. Rheumatoid nodules are frequently seen, at the subcutaneous soft tissues of repetitive mechanical irritation points, and prominent bones. There have been no reported cases of rheumatoid nodules, extending just beneath the ischial tuberosity bone. A 68-year-old woman with a seven-year history of rheumatoid arthritis, suffered for six months, from right buttock swelling and discomfort in seating. A cystic lesion postero-inferior to the ischial tuberosity, was noted in the MRI scan, which was thought to be ischiogluteal bursitis, because of its characteristic location and appearance. Histopathologic analysis and gross findings on the operation, revealed no evidence of bursitis.

The MRI Findings of Flexor Digitorum Accessorius Longus Muscle: a Case Report

The flexor digitorum accessorius longus (FDAL) is the most common accessory muscle found in the posterior compartment of the ankle area. The accessory muscle in this area such as the FDAL may be incidentally identified on magnetic resonance images (MRI). There are some case reports about the FDAL in cadaver researches. However, the MRI findings about the FDAL have been reported in a few cases. In this paper, we report a case of the FDAL incidentally identified on MRI with review of the literature about the FDAL.

Anomalous Insertion of the Medial Meniscus into the Anterior Cruciate Ligament: A Case Report

Anomalies of the medial meniscus are rare and difficult to diagnose clinically. Among these anomalies, anomalous insertion of the medial meniscus into the anterior cruciate ligament is rare. Most of the reported cases had no relation to clinical symptoms and were found incidentally during arthroscopy. We report a rare case of anomalous insertion of the medial meniscus into the anterior cruciate ligament with a brief review of the literature.

Simultaneous Bilateral Quadriceps Tendon Rupture in Patient with Secondary Hyperparathyroidism due to Chronic Renal Failure: A Case Report

Simultaneous bilateral spontaneous rupture of the quadriceps tendon is a very rare condition and only a few cases have been reported in the literature. The etiology is not clear yet. But it occurs infrequently in patients with chronic metabolic disorders, such as secondary hyperparathyroidism due to chronic renal failure. We describe a case of simultaneous spontaneous bilateral quadriceps tendon tupture in a 36-year-old male patient with secondary hyperaprathyroidism due to chronic renal failure.

A Case Report of the Occurrence of a Rare Middle Mediastinal Thymoma in a Young Woman

Thymomas are the most common form of primary tumor in the anterior mediastinum. However, the occurrence of thymomas in the middle mediastinum is rare. To the best of our knowledge, no cases have been reported in young patients. Here, we report the CT and MRI findings of a middle mediastinal thymoma case in a 21-year-old woman.

Leiomyosarcoma of the Ovarian Vein: a Case Report with Radiological Findings

Leiomyosarcomas of the ovarian vein are very rare. Four cases have been reported in the English language clinical literature. We present a case of leiomyosarcomas where the use of multi-detector CT had a substantial role in the establishment of the preoperative diagnosis. The radiological images as well as intraoperative features are illustrated. We also discuss the radiological findings of the ovarian vein leiomyosarcoma in comparison with those of other venous or retroperitoneal leiomyosarcomas. We expect that the use of multi-detector CT will be the choice for the diagnostic work-up of vascular leiomyosarcomas.

Metastatic Renal Cell Carcinoma to Unusual Locations: A Case Report

Renal cell carcinoma is a tumor that commonly occurs with distant metastases and typically metastasizes to the following distant sites, listed in order of descending frequency: the lung and mediastinum, bone, liver, contralateral kidney or adrenal gland, and brain. However, metastases to the face, skin, and skeletal muscle are extremely rare. We report here a case of a metastatic renal cell carcinoma involving the face, skeletal muscles and skin simultaneously.

Breast Arterial Calcification on Mammogram: Correlation with Carotid Arterial Atherosclerosis on Ultrasonogram

PURPOSE: To investigate the incidence of breast arterial calcification in Korean women, and to determine its association with systemic diseases and carotid arterial atherosclerosis. MATERIALS AND METHODS: One thousand seven hundred and thirteen female subjects who underwent mammography at a health care center between May 1999 and May 2000 were included in this study. Of the total, 172 were found to have breast arterial calcification, and were classified according to age. The coincidence of hypertension, diabetes mellitus and hyperlipidemia was examined in both the subject group and the control group selected on the same age basis. To investigate the presence and degree of carotid atherosclerosis, sonographic maging was performed and the findings were compared between the two groups. RESULTS: The incidence of breast arterial calcification showed statistically significant differences according to age, with a higher incidence in older patients (p<0.05). However, there was no statistical difference in the incidence of hypertension, hyperlipidemia, and diabetes mellitus between groups. Carotid atherosclerosis was subjects more prevalent among subjects than in the control group (p<0.05), though there was no statistically significant difference in the degree of luminal stenosis. CONCLUSION: The most common pathologic cause of breast arterial calcification is arteriosclerosis. Breast arterial calcification is demonstrated at mammography, along with other clinical risk factors for atherosclerosis or coincidental neurologic symptoms. We stress that further evaluation of the carotid artery is necessary.

Viable myocardium in reperfused acute myocardial infarction: rest and stress first-pass mr imaging

Feasibility of identifying viable myocardium in rest and stress magnetic resonance imaging (MRI) was evaluated using 3 hr occlusion and 30 min reperfusion model of left anterior descending (LAD) coronary artery in 12 felines. At rest MRI, viable myocardium confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC)- staining showed rapid signal intensity (SI) rise followed by gradual decline not significantly different from normal myocardium that the two hyperperfused regions were distinguishable only from the hypoperfused nonviable myocardium. At stress MRI, hyperemia induced perfusion change was most pronounced in normal myocardium with earlier and greater peak enhancement followed by brisk 'washout' phase while minimally augmented enhancement in viable myocardium was still in 'washin' phase. From these findings, it was concluded that viable myocardium is identified in rest and stress MRI as redistributing hypo- perfusion compared to persistent hyper-perfusion of the normal myocardium and the persistent hypo-perfusion of the nonviable myocardium.

CT Densitometry of Lung Mass: The Effect of Reconstruction Algorithm

PURPOSE: To evaluate the effect of reconstruction algorithms on the CT measurement of mean lung mass density and normal thoracic structures. MATERIALS AND METHODS: Forty-six patients with a 2-9cm-sized lung mass underwent thoracic CT examinations with intravenous contrast enhancement and using a CT HiSpeed Advantage scanner (GE Medical Systems). In each examination, the axial image of the lung mass was reconstructed using soft, standard, detail, and bone algorithms. The mean value and standard deviation of mass density in Hounsfield Units (HU) were measured using ROIs of three different sizes (50 mm2, 200 mm2, and 350 mm2 or more), and the same method was used to measure the density of normal lung, muscle, bone, and vessels. In 21 patients, mass density was also measured on unenhanced and delayed enhanced images and the degree of enhancement was calculated. RESULTS: The average maximum difference in mean mass density in the images of the four different algorithms was less than 1 (range, 0.1 -1.9) HU (ROI size, 350 mm2 or more), 0 -4.2 HU (200 mm 2), and 0.1 -3.6 HU (50mm2). The average maximum difference in the degree of lung mass enhancement was 0.5 -1.2 (range, 0 -1.6 )HU (ROI size, 350 mm2 or more). The mean density of the four normal thoracic structures was highest in images reconstructed with the bone algorithm, though there was no significant difference between the four different algorithms (p = 1.000). CONCLUSION: The measured mean CT density of a lung mass larger than 2 cm does not significantly change according to the reconstruction algorithm used. When using a small ROI, however, the density difference may increase.

Effect of Steroid on Brain Tumors and Surround Edemas: Observa tion with Regional Cere b ral Blood Volume (rCBV) Maps of Perfusion MRI

PURPOSE: To observe the hemodynamic change in brain tumors and peritumoral edemas after steroid treat-ment, and then nvestigate the clinical usefulness of perfusion MRI. MATERIALS AND METHODS: We acquired conventional and perfusion MR images in 15 patients with various in-tracranial tumors (4 glioblastoma multiformes, 4 meningiomas, 3 metastatic tumors, 1 anaplastic ependymo-ma, 1 anaplastic astrocytoma, 1 hemangioblastoma, and 1 pilocytic astrocytoma). For perfusion MR imaging, a 1.5T unit employing the gradient-echo EPI technique was used, and further perfusion MR images were ob-tained 2-10 days after intravenous steroid therapy. After processing of the raw data, regional cerebral blood volume (rCBV) maps were reconstructed. The maps were visually evaluated by comparing relative perfusion in brain tumors and peritumoral edemas with that in contralateral white matter. Objective evaluations were performed by comparing the perfusion ratios of brain tumors and peritumoral edemas. RESULTS: Visual evaluations of rCBV maps, showed that in most brain tumors (67%, 10/15), perfusion was high before steroid treatment and showed in (80%, 12/15) decreased afferwards. Objective evaluation, showed that in all brain tumors, perfusion decreased. Visual evaluation of perfusion change in peritumoral edemas revealed change in only one case, but objective evaluation indicated that perfusion decreased signifi-cantly in all seven cases. CONCLUSIONS: rCBV maps acquired by perfusion MR imaging can provide hemodynamic information about brain tumors and peritumoral edemas. Such maps could prove helpful in the preoperative planning of brain tumor surgery and the monitoring of steroid effects during conservative treatment.

Effect of Steroid on Brain Tumors and Surround Edemas: Observa tion with Regional Cere b ral Blood Volume (rCBV) Maps of Perfusion MRI

PURPOSE: To observe the hemodynamic change in brain tumors and peritumoral edemas after steroid treat-ment, and then nvestigate the clinical usefulness of perfusion MRI. MATERIALS AND METHODS: We acquired conventional and perfusion MR images in 15 patients with various in-tracranial tumors (4 glioblastoma multiformes, 4 meningiomas, 3 metastatic tumors, 1 anaplastic ependymo-ma, 1 anaplastic astrocytoma, 1 hemangioblastoma, and 1 pilocytic astrocytoma). For perfusion MR imaging, a 1.5T unit employing the gradient-echo EPI technique was used, and further perfusion MR images were ob-tained 2-10 days after intravenous steroid therapy. After processing of the raw data, regional cerebral blood volume (rCBV) maps were reconstructed. The maps were visually evaluated by comparing relative perfusion in brain tumors and peritumoral edemas with that in contralateral white matter. Objective evaluations were performed by comparing the perfusion ratios of brain tumors and peritumoral edemas. RESULTS: Visual evaluations of rCBV maps, showed that in most brain tumors (67%, 10/15), perfusion was high before steroid treatment and showed in (80%, 12/15) decreased afferwards. Objective evaluation, showed that in all brain tumors, perfusion decreased. Visual evaluation of perfusion change in peritumoral edemas revealed change in only one case, but objective evaluation indicated that perfusion decreased signifi-cantly in all seven cases. CONCLUSIONS: rCBV maps acquired by perfusion MR imaging can provide hemodynamic information about brain tumors and peritumoral edemas. Such maps could prove helpful in the preoperative planning of brain tumor surgery and the monitoring of steroid effects during conservative treatment.

MR Imaging Findings of Patients with Mesial Temporal Sclerosis

PURPOSE: To evaluate the MR imaging findings of patients with mesial temporal sclerosis. MATERIALS AND METHODS:We retrospectively reviewed the MR imaging findings of 116 patients diagnosed by MRI as suffering from mesial temporal sclerosis. In 18 of these, the condition was also histologically proven. RESULTS: Among the 116 patients, volume loss of the hippocampus was found in 95 (81.9%) and signal changes of the hippocampus in 53 (45.7%). Decreased signal intensity in the hippocampus on T1-weighted images was found in 13 (11.2%) and increased signal on T2-weighted images in 50 (43.1%). Signal abnormality in the hip-pocampus on both T1- and T2-weighted images was found in ten, and associated extrahippocampal abnormali-ties, as follows, in 20 (17.2%): atrophy of the fornix (n=10), atrophy of the mammillary body (n=8), atrophy of the amygdala (n=10), atrophy or increased T2 signal intensity of the anterior thalamic nuclei (n=2), atrophy of the cingulate gyrus (n=2), atrophy or increased signal intensity of the anterior temporal lobe (n=8), and cere-bral hemiatrophy (n=4). CONCLUSION: A high T2 signal and atrophy of the hippocampus are the most common and important MRI findings of mesial temporal sclorosis. Other abnormal findings, if any, which may be found in extrahippocampal structures such as the fornix, mammillary body and temporal lobe, should, however, also be carefully observed

Radiologic Assessment of Spinal CSF Leakage in Spontaneous Intracranial Hypotension

PURPOSE: To assess the usefulness of imaging modalities in the detection of spinal CSF leakage in spontaneous intracranial hypotension. MATERIALS AND METHODS: Fifteen patients who complained of postural headache without any preceding cause showed typical brain MR findings of intracranial hypotension, including radiologically confirmed CSF leakage. All fifteen underwent brain MRI and radionuclide cisternography. CT myelography was performed in eight patients and spinal MRI in six. Medical records, imaging findings and the incidence of spinal CSF leakage during each modality were retrospectively reviewed. RESULTS: CSF leakage was most common at the cervicothoracic junction, where in seven of 15 cases it was seen on radionuclide cisternography as increased focal paraspinal activity. Leakage was noted at the mid-thoracic level in three patients, at the upper thoracic level in two, and at the cervical and lumbar levels in the remaining two. In two patients multiple CSF leaks were noted, and in all, early radioactive accumulation in the bladder was visualized. CT myelography revealed extrathecal and paraspinal contrast leakage in three of eight patients, and among those who underwent spinal MRI, dural enhancement was observed at the site of CSF leakage in all six, abnormal CSF signal in the neural foramen in one, and epidural CSF collection in one. CONCLUSION: Radionuclide cisternography is a useful method for the detection of CSF leakage in spontaneous intracranial hypotension. CT myelography and spinal MRI help determine the precise location of leakage.

Hyperacute Intracerebral Hemorrhage: Comparison of EPI and Other MR Sequences

PURPOSE: To evaluate the detection rate of hyperacute intracerebral hemorrhage in echo planar imaging (EPI) and other MR sequences. MATERIALS AND METHODS: Intracerebral hemorrhage was experimentally induced in ten rats. EPI, fast spin-echo (FSE) T2 weighted images, fluid attenuated inversion recovery (FLAIR), spin-echo (SE) T1 weighted images and gradient echo (GE) T1 weighted images of rat's brains were obtained 2 hours after onset of intracerebral hemorrhage. EPI and FSE T2 images were additionally obtained 30 min and 1 hour after onset of hemorrhage in 3 and 6 rat, repeatedly. For objective visual assessment, discrimination between the lesion and normal brain parenchyma was evaluated on various MR sequences by three radiologists. For quantitative assessment, contrast-to-noise ratio (CNR) was calculated for hemorrhage-normal brain parenchyma. Statistical analysis was performed using the Wilcoxon-Ranks test. RESULTS: EPI, FLAIR, and FSE T2 images showed high signal intensity lesions. The lesion discrimination was easier on EPI than on other sequences, and also EPI showed higher signal intensity for the subjective visual assessment. In quantitative evaluation, CNR of the hemorrhagic lesion versus normal brain parenchyma were higher on EPI and FLAIR than in other MR sequences (p0.10). On MR images obtained 30 minutes and 1 hour after the onset of intracerebral hemorrhage, the lesion detection was feasible on both EPI and FSE T2 images showing high signal intensity. CONCLUSION: EPI showed higher detection rate as compared with other MR sequences and could be useful in early detection and evaluation of intracerebral hemorrhage.

Radiologic Findings of Korean Gaucher Disease

PURPOSE: To document the radiologic characteristics of Korean Gaucher disease. MATERIALS AND METHODS: Fifteen bone marrow biopsy and laboratory data confirmed Gaucher disease patients (age 1 -21, mean 10.9 yr) wereundertaken plain X ray and MRI. Number of type I were 10, type II, 2, type III, 3. Seven were splenectomized oninitial evaluation or during follow up. Five enzyme treated patient were undertaken follow-up MR examinationduring 6 -40 month with 6 month interval. Conventional T1 and T2WI of spine and femur was performed and FMPSPGR inand out of phase image was also done. Volume of liver and spleen were measured, and bone marrow infiltration andpresence of infarction were scored according to 6 scale scoring system. Clinical data were also reviewed andcorrelated with the MR findings. RESULTS: Marrow infiltration was noted in 71.4% of all patients in MRI, while itwas in 45.7% with plain radiography. Type I group showed marrow infiltration in all but one cases, which wasparallel with ages, SGPT, and presence of osteopenia, reversely correlated with spleen size. Severe bonecomplications (infarction or fracture) were noted in 7 of 10 type I group, and 6 patients showed severe growthretardation (below 3rd percentile). Follow up MR examination of 5 patient showed decrease in liver and spleen sizefirst without bone change until 6 months. There showed bone regeneration in 2 patient 1 year after, and increasedfat signal in one patient 3.5 years after. In and out of phase images couldn't help in quantifying fatcomposition in bone marrow. CONCLUSION: Korean Gaucher patients revealed as more severe skeletal complicationsthan others reported from Western groups. MR examination is a effective modality to evaluate and monitor ofGaucher patients.

Natural Evolution of Grafted Anterior Cruciate Ligament of the Knee: Prospective Follow-up MR Studies

PURPOSE: To described the MR findings in the periodic changes of the size and signal intensity ofreconstructed anterior cruciate ligament (ACL) of the knee and the efficacy of oblique axial imaging in patientswho underwent arthroscopic ACL reconstruction using autogenous patellar tendon. MATERIALS AND METHODS: Twenty-onepatients who had undergone ACL reconstruction were evaluated by follow-up MRI at postoperative 1 week, 1, 2, 3 and6 months, and 1 year, Conventional Fast-Spin-Echo (FSE) sagittal and coronal images and oblique axial images(proton density and T2-WI; VEMP TR/TE, 2000/20/70) were obtained perpendicular to the ligament, and using an ROIcurve in the intra-articular area, periodic changes in the cross-sectional area were evaluated by proton densityimaging and signal intensity by T2WI imaging. Cross-sectional morphology was categorized as either smooth, andround or notch-shaped and periodic changes in configuration were observed. In three cases, we evaluated the retearof reconstructed ACL by comparing the oblique axizl image obtained by conventional sagittal and coronal imaging. RESULTS: The cross-sectional area and signal intensity of grafted ACL increased significantly (p<0.05) after 3months and at 1 year, respectively. Cross-sectional morphology was smooth and round in 86% of cases, and notchedin 14%, and during follow-up MR studies, no periodic changes were seen. Notch-shaped ACL and decreased perigraftsignal intensity, as seen on sagittal images, could lead to a misdiagnosis of partial tear ; on oblique axialimages, ACL and perigraft signal intensity were found to be normal. CONCLUSION: During the natural evolution ofgrafted ACL, cross-sectional area and signal intensity increased significantly after 3 months and at 1 year,respectively ; on follow-up MR studies, cross-sectional morphology did not change, however. Oblique axial imagingprovides important information for evaluating whether the reconstructed ACL is torn or not.