Incidence of adverse drug reaction among 6 iodinated contrast media

Purpose@#Contrast media is one of the most common cause of adverse drug reaction (ADR) in adult. However, there was little data reported about differences in ADR ratio and severity among iodinated contrast media (ICM). @*Methods@#Medical records of 627,049 patients who performed computed tomography scan using low-osmolar nonionic iodinated contrast media from January 2015 to December 2018 were retrospectively reviewed. A total of 6 ICMs including iomeprol, iohexol, iopromide, iobitridol, ioversol, and iopamidol were used in this period. The incidence of ADR was compared to their total usage and dosage between each contrast media. @*Results@#The incidence of ADR of iopromide (1.36%) and iomeprol (1.27%) was the highest when compared with the average incidence of 1% of 6 ICMs. Ioversol (0.67%), iohexol, and iobitridol (0.74%) had the lower incidence of ADR. The order of results adjusted by actual administered dosage, the use of premedication, and the prior exposure history of ICMs was similar. The fraction of moderate and severe ADR in overall ADR was slightly different, but not proportional to the incidence of ADR. @*Conclusion@#The incidence of ADR among 6 low-osmolar nonionic ICMs was significantly different when compared by the total number of usage and the total volume of dose. The incidence of ADR varied by nearly 2-fold depending on ICMs. Further study might need to explore the reason for the difference of incidence.

Diagnostic Imaging for Physical Abuse in Children

Physical abuse is a significant cause of morbidity and mortality in the pediatric population. Young children, particularly in the first year of life, are most vulnerable to physical abuse. To evaluate suspected physical abuse, radiologists play a vital role by detecting radiological findings suggestive of physical abuse and differentiating them from other pathologies. This review focuses on radiologic findings, including those for fractures, abusive head trauma, spinal injury, and thoracoabdominal injury, commonly discovered in physically abused children, with special emphasis on biomechanical forces that produce injuries.

Principles for evaluating the clinical implementation of novel digital healthcare devices

With growing interest in novel digital healthcare devices, such as artificial intelligence (AI) software for medical diagnosis and prediction, and their potential impacts on healthcare, discussions have taken place regarding the regulatory approval, coverage, and clinical implementation of these devices. Despite their potential, ‘digital exceptionalism’ (i.e., skipping the rigorous clinical validation of such digital tools) is creating significant concerns for patients and healthcare stakeholders. This white paper presents the positions of the Korean Society of Radiology, a leader in medical imaging and digital medicine, on the clinical validation, regulatory approval, coverage decisions, and clinical implementation of novel digital healthcare devices, especially AI software for medical diagnosis and prediction, and explains the scientific principles underlying those positions. Mere regulatory approval by the Food and Drug Administration of Korea, the United States, or other countries should be distinguished from coverage decisions and widespread clinical implementation, as regulatory approval only indicates that a digital tool is allowed for use in patients, not that the device is beneficial or recommended for patient care. Coverage or widespread clinical adoption of AI software tools should require a thorough clinical validation of safety, high accuracy proven by robust external validation, documented benefits for patient outcomes, and cost-effectiveness. The Korean Society of Radiology puts patients first when considering novel digital healthcare tools, and as an impartial professional organization that follows scientific principles and evidence, strives to provide correct information to the public, make reasonable policy suggestions, and build collaborative partnerships with industry and government for the good of our patients.

Principles for evaluating the clinical implementation of novel digital healthcare devices

With growing interest in novel digital healthcare devices, such as artificial intelligence (AI) software for medical diagnosis and prediction, and their potential impacts on healthcare, discussions have taken place regarding the regulatory approval, coverage, and clinical implementation of these devices. Despite their potential, ‘digital exceptionalism’ (i.e., skipping the rigorous clinical validation of such digital tools) is creating significant concerns for patients and healthcare stakeholders. This white paper presents the positions of the Korean Society of Radiology, a leader in medical imaging and digital medicine, on the clinical validation, regulatory approval, coverage decisions, and clinical implementation of novel digital healthcare devices, especially AI software for medical diagnosis and prediction, and explains the scientific principles underlying those positions. Mere regulatory approval by the Food and Drug Administration of Korea, the United States, or other countries should be distinguished from coverage decisions and widespread clinical implementation, as regulatory approval only indicates that a digital tool is allowed for use in patients, not that the device is beneficial or recommended for patient care. Coverage or widespread clinical adoption of AI software tools should require a thorough clinical validation of safety, high accuracy proven by robust external validation, documented benefits for patient outcomes, and cost-effectiveness. The Korean Society of Radiology puts patients first when considering novel digital healthcare tools, and as an impartial professional organization that follows scientific principles and evidence, strives to provide correct information to the public, make reasonable policy suggestions, and build collaborative partnerships with industry and government for the good of our patients.

Radiation Doses of Various CT Protocols: a Multicenter Longitudinal Observation Study

Emerging concerns regarding the hazard from medical radiation including CT examinations has been suggested. The purpose of this study was to observe the longitudinal changes of CT radiation doses of various CT protocols and to estimate the long-term efforts of supervising radiologists to reduce medical radiation. Radiation dose data from 11 representative CT protocols were collected from 12 hospitals. Attending radiologists had collected CT radiation dose data in two time points, 2007 and 2010. They collected the volume CT dose index (CTDIvol) of each phase, number of phases, dose length product (DLP) of each phase, and types of scanned CT machines. From the collected data, total DLP and effective dose (ED) were calculated. CTDIvol, total DLP, and ED of 2007 and 2010 were compared according to CT protocols, CT machine type, and hospital. During the three years, CTDIvol had significantly decreased, except for dynamic CT of the liver. Total DLP and ED were significantly decreased in all 11 protocols. The decrement was more evident in newer CT scanners. However, there was substantial variability of changes of ED during the three years according to hospitals. Although there was variability according to protocols, machines, and hospital, CT radiation doses were decreased during the 3 years. This study showed the effects of decreased CT radiation dose by efforts of radiologists and medical society.

Early Diagnosis of Perinatal Ischemic Stroke Based on Clinical and Radiological Characteristics

PURPOSE: Perinatal ischemic stroke (PIS) has been increasingly recognized and regarded as one of the major causes of neurological disability occurring in the neonatal period. Due to its vague presenting symptoms, the clinical diagnosis of PIS can be delayed. The aim of this study was to delineate the clinical and radiological characteristics of PIS in order to establish its early diagnosis. METHODS: From January 2002 to October 2010, 24 neonates with evidence of ischemic cerebral infarction on brain magnetic resonance imaging (MRI) were enrolled. Perinatal and neonatal clinical characteristics, electroencephalogram (EEG), and brain MRI findings were retrospectively reviewed. Using those data, analysis was done to elicit clues for early diagnosis and prognostic factors of PIS. RESULTS: Sixteen males and eight females were diagnosed with PIS. Twelve cases presented with apnea and ten patients with seizures. The diagnosis of PIS was confirmed by brain MRI. Sixteen patients (66.7%) had infarction in the territory of the middle cerebral artery, and fifteen neonates had infarction in the left hemisphere. Of 11 infants who presented with a focal lesion on brain MRI, three patients were diagnosed by diffusion weighted images (DWI). Their T2- and FLAIR sequences showed subtle signal changes, whereas DWI revealed bright signal intensity. Thirteen patients were included in the delayed diagnostic group (diagnostic interval >24 hours). In those patients, apnea (69.2%) was more likely than seizures (15.4%) to be the initial symptom. The extent of the lesion on brain MRI was likely to be a better predictor of the neurologic outcome. Hemiplegia or hemiparesis was found in seven patients who had extensive lesions involving the gray and white matter, internal capsule, and basal ganglia. CONCLUSION: PIS should be considered as a differential diagnosis for neonates who present with apnea, lethargy or subtle seizures. DWI of brain MRI is very useful for early diagnosis of PIS. The extent of the lesion was also found to be significantly associated with poor outcome.

Erratum

No abstract available.

Diffusion and Perfusion Characteristics of MELAS (Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke-Like Episode) in Thirteen Patients

OBJECTIVE: We analyzed the diffusion and perfusion characteristics of acute MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode) lesions in a large series to investigate the controversial changes of the apparent diffusion coefficient (ADC) that were reported in prior studies. MATERIALS AND METHODS: We analyzed 44 newly appearing lesions during 28 stroke-like episodes in 13 patients with MELAS. We performed a visual assessment of the MR images including the ADC and perfusion maps, comparison of the ADC between the normal and abnormal areas, comparison of % ADC between the 44 MELAS lesions and the 30 acute ischemic infarcts. In addition, the patterns of evolution on follow-up MR images were analyzed. RESULTS: Decreased, increased, and normal ADCs were noted in 16 (36%), 16 (36%), and 12 (27%) lesions, respectively. The mean % ADC was 102 +/- 40.9% in the MELAS and 64 +/- 17.8% in the acute vascular infarcts (p < 0.001), while perfusion imaging demonstrated hyper-perfusion in six acute MELAS lesions. On follow-up images, resolution, progression, and tissue loss were noted in 10, 4, and 17 lesions, respectively. CONCLUSION: The cytotoxic edema gradually evolves following an acute stroke-like episode in patients with MELAS, and this may overlap with hyper-perfusion and vasogenic edema. The edematous swelling may be reversible or it may evolve to encephalomalacia, suggesting irreversible damage.

Comparison of Clinico-Radiological Features between Congenital Cystic Neuroblastoma and Neonatal Adrenal Hemorrhagic Pseudocyst

OBJECTIVE: To evaluate the radiological and clinical findings of congenital cystic neuroblastomas as compared with those of the cystic presentation of neonatal adrenal hemorrhage. MATERIALS AND METHODS: We analyzed the US (n = 52), CT (n = 24), and MR (n = 4) images as well as the medical records of 28 patients harboring congenital cystic neuroblastomas (n = 16) and neonatal adrenal hemorrhagic pseudocysts (n = 14). The history of prenatal detection, location, size, presence of outer wall enhancement, internal septations, solid portion, calcification, turbidity, vascular flow on a Doppler examination, and evolution patterns were compared in two groups of cystic lesions, by Fischer's exact test. RESULTS: All (100%) neuroblastomas and three (21%) of the 14 hemorrhagic pseudocysts were detected prenatally. Both groups of cystic lesions occurred more frequently on the right side; 11 of 16 (69%) for neuroblastomas and 11 of 14 (79%) for hemorrhagic pseudocysts. The size, presence of solid portion, septum, enhancement, and turbidity did not differ significantly (p > 0.05) between the two groups of cystic lesions. However, tiny calcifications (n = 3) and vascular flow on color Doppler US (n = 3) were noted in only neuroblastomas. The cystic neuroblastomas became complex solid and cystic masses, and did not disappear for up to 90 days in the three following cases, whereas 11 of the 14 (79%) hemorrhagic pseudocysts disappeared completely and the three remaining (27%) evolved to calcifications only. CONCLUSION: Although the imaging findings of two groups of cystic lesions were similar, prenatal detection, the presence of calcification on initial images, vascularity on color Doppler US, and evolution to a more complex mass may all favor neuroblastomas.

MR Imaging of Intracranial Pediatric Meningiomas: Manifestations in 16 Patients

PURPOSE: To describe the clinical, MR imaging, and pathologic findings of pediatric meningiomas. MATERIALS AND METHODS: The authors retrospectively reviewed the medical records and MR images of 16 pediatric patients with pathologically proven meningioma. Mean patient age at diagnosis was 14 years (range, 3-18). MR images were reviewed for details of lesion sizes, locations, signal intensity (SI), marginal characteristics, internal architectures, enhancements, and dural and parenchymal changes. The findings of other imaging modalities and of pathological examinations were also analyzed. RESULTS: Mean tumor size was 5.24 cm (range, 1.3-18.1 cm) and locations were supratentorial in 12 and infratentorial in 4. SI of masses were variable, that is, high in 9, iso in 4, and low in 3 on T2 weighted images (T2WI), and low (n=11), iso (n=4), or high (n=1) on T1WI images. All lesions were visualized as well-demarcated enhancing masses. Five of the tumors were heterogeneous with cystic or necrotic components. Dural attachment was observed in 11 patients and adjacent brain edema in 10. Tumors exhibited hyperdense (n=6) or isodense (n=4) on nonenhanced CT scans, and 3 of the 7 angiograms demonstrated blood supply from the internal carotid artery. Pathologic examinations revealed the following subtypes; transitional cell (n=4), meningotheliomatous (n=4), chordoid (n=2), fibrous (n=2), clear cell (n=1), hyalinized (n=1), rhabdoid papillary (n=1), and atypical (n=1). CONCLUSION: Pediatric meningiomas occur usually in teenagers, have diverse pathological types, and may produce atypical imaging findings, such as, a heterogeneous internal content or findings suggestive of intraaxial tumors.

T1-weighted MR Imaging of the Neonatal Brain at 3.0 Tesla: Comparison of Spin Echo, Fast Inversion Recovery, and Magnetization-prepared Three Dimensional Gradient Echo Techniques

PURPOSE: The purpose of this study was to evaluate the usefulness of fast inversion recovery (FIR) and magnetization-prepared three dimensional gradient echo sequence (3D GRE) T1-weighted sequences for neonatal brain imaging compared with spin echo (SE) sequence in a 3T MR unit. MATERIALS AND METHODS: T1-weighted axial SE, FIR and 3D GRE sequences were evaluated from 3T brain MR imaging in 20 neonates. The signal-to-noise ratio (SNR) of different tissues was measured and contrast-to-noise ratios (CNR) were determined and compared in each of the sequences. Visual analysis was carried out by grading gray-white matter differentiation, myelination, and artifacts. The Wilcoxon signed ranked test was used for evaluation of the statistical significance of CNR differences between the sequences. RESULTS: Among the three sequences, the 3D GRE had the best SNRs. CNRs obtained with FIR and 3D GRE were statistically superior to those obtained with SE; these CNRs were better on the 3D GRE compared to the FIR. Gray to white matter differentiation and myelination were better delineated on the FIR and 3D GRE than the SE. However, motion artifacts were more commonly observed on the 3D GRE and flow-related artifacts of vessels were frequently seen on the FIR. CONCLUSION: FIR and 3D GRE are valuable alternative T1-weighted sequences to conventional SE imaging of the neonatal brain at 3T providing superior image quality.

Comparison of Radiofrequency Ablation Lesion Size with Occlusion of Renal Vessels in Rabbit Kidneys: Occlusion of Renal Artery, Vein, and Both Vessels

PURPOSE: The purpose of this study was to compare the in-vivo efficiency of vascular occlusion on radiofrequency ablation (RFA) lesion size in a rabbit kidney model. MATERIALS AND METHODS: RFA lesions were created in a single kidney in 20 rabbits using an internally cooled electrode. Twenty ablation zones (1 per kidney) were created using 4 different regimens: RFA without vascular occlusion (n = 5), RFA with renal artery occlusion (n = 5), RFA with renal vein occlusion (n = 5), RFA with renal artery and vein occlusion (n = 5). Seven days later, the rabbits were sacrificed and the lesions were excised. These groups were then compared with respect to the dimensions of the ablation zones and the changes in impedance and current during RFA. RESULTS: The maximum ablation zone width was the greatest in the renal artery and vein occlusion group (21.0+/-1.4 mm), followed by the renal artery occlusion group (17.8+/-1.0 mm), the renal vein occlusion group (17.4+/-1.1 mm), and the nonocclusion group (7.8+/-2.4 mm) (p < 0.05). No significant differences were observed for impedances and currents between the 4 groups. CONCLUSION: Vascular occlusion combined with RFA effectively increased ablation zone dimensions compared with RFA alone, and the best effect was accomplished by combined renal artery and vein occlusion.

Serial CT Findings of Paragonimus Infested Dogs and the Micro-CT Findings of the Worm Cysts

OBJECTIVE: To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. MATERIALS AND METHODS: This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. RESULTS: The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. CONCLUSION: The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus.

Differentiation of Hyperplastic from Metastatic Lymph Nodes Using a Lymph Node Specific MR Contrast Agent Gadofluorine M

PURPOSE: We wanted to evaluate the value of a lymph node specific MR contrast agent, Gadofluorine M, for the differentiation of hyperplastic and metastatic lymph nodes. MATERIALS AND METHODS: This study included thirty-one rabbits. In ten rabbits, an injection of egg yolk or feces of rat into the calf muscles induced hyperplasia of the lymph node. In sixteen rabbits, metastasis of the lymph node was induced by implantation of VX2 tumor. Five rabbits were normal control models. We acquired the T1-, T2-weighted and SPGR coronal imaging before enhancement with 1.5 T MR. After injection of Gadofluorine M (5 micromol/mL, total amount: 4 mL) interstitially into the interdigital skin fold of the hind limb, we acquired the SPGR coronal imaging at 15, 30, 60 and 90 minutes. We calculated the signal-to-noise ratios on the sequential images, and we recorded the number, size and location of the popliteal and iliac lymph nodes. Three readers assessed the state of the lymph nodes according to the pattern of enhancement: they were deemed hyperplastic nodes when totally enhanced and as metastatic nodes when there was no or partial enhancement. We also compared the imaging patterns with the histopathological results. RESULTS: Among the 26 hyperplasia- or metastasis-induced rabbits, two rabbits were excluded because of failure to be enhanced. Histopathologic evaluation of the 24 rabbits detected one hundred seventeen lymph nodes: forty-six lymph nodes in nine hyperplasia-induced rabbits and seventy-one (metastasis in twenty-eight) lymph nodes in fifteen metastasis-induced rabbits. Out of one hundred two lymph nodes that were larger than 5 mm in size, MR enabled us to detect one hundred one lymph nodes (99.1%). The means of sensitivity, specificity, and the positive and negative predictive values for the diagnosis of lymph node metastasis by three readers were 97.6% (82/84), 98.2% (215/219), 95.3% (82/86), and 99.1% (215/217), respectively (p < 0.05). CONCLUSION: Interstitial MR lymphography using Gadofluorine M showed excellent results in differentiating hyperplastic from metastatic lymph nodes.

Hepatic Radiofrequency Ablation Using Multiple Probes: Ex Vivo and In Vivo Comparative Studies of Monopolar versus Multipolar Modes

OBJECTIVE: We wanted to compare the efficiency of multipolar radiofrequency ablation (RFA) using three perfused-cooled electrodes with multiple overlapping- and simultaneous monopolar techniques for creating an ablation zone in ex vivo bovine livers and in in vivo porcine livers. MATERIALS AND METHODS: In the ex vivo experiments, we used a 200 W generator (Valleylab, CC-3 model) and three perfused-cooled electrodes or internally cooled electrodes to create 30 coagulation zones by performing consecutive monopolar RFA (group A, n = 10), simultaneous monopolar RFA (group B, n = 10) or multipolar RFA (group C, n = 10) in explanted bovine livers. In the consecutive mode, three ablation spheres were created by sequentially applying 150 watts radiofrequency (RF) energy to the internally cooled electrodes for 12 minutes each for a total of 36 minutes. In the simultaneous monopolar and multipolar modes, RF energy was concurrently applied to the three perfused-cooled electrodes for 20 minutes at 150 watt with instillation of 6% hypertonic saline at 2 mL/min. During RFA, we measured the temperatures of the treated area at its center. The changes in impedance, the current and liver temperature during RFA, as well as the dimensions of the thermal ablation zones, were compared among the three groups. In the in vivo experiments, three coagulations were created by performing multipolar RFA in a pig via laparotomy with using same parameter as the ex vivo study. RESULTS: In the ex vivo experiments, the impedance was gradually decreased during the RFA in groups B and C, but in group A, the impedance was increased during RFA and this induced activation by the pulsed RF technique. In groups A, B and C, the mean final-temperature values were 80 +/- 10 degrees C, 69+/-18 degrees C and 79 +/- 12 degrees C, respectively (p < 0.05). The multipolar mode created a larger volume of ablation than did the other modes: 37.6 +/-4.0 cm3 (group A); 44.9 +/- 12.7 cm3 (group B); and 78.9 +/- 6.9 cm3 (group C) (p < 0.05). In the in vivo experiment, the pig well tolerated the RFA procedure and no major complications occurred during the 4 days of the follow-up period. The mean volume of coagulations produced by multipolar RFA in the pig liver was 60.5+/-17.9 cm3. CONCLUSION: For the multiple probe RFA, the multipolar mode with hypertonic saline instillation was more efficient in generating larger areas of thermal ablation than either the consecutive or simultaneous monopolar modes.

Differentiation of Tuboovarian Abscess from Endometriosis: CT Indicators

PURPOSE: To assess and compare CT findings of surgically confirmed cases of tuboovarian abscesses (TOA) and endometriosis in order to identify indicators which may be helpful in making correct preoperative diagnoses. MATERIALS AND METHODS: Of the 35 consecutive patients with surgically confirmed TOA, CT images were available for 11 of those patients. As a comparative group, 36 patients with surgically confirmed endometriosis with CT images were selected. CT images of TOA were compared with those of endometriosis. A retrospective analysis of the CT images of both groups was performed without knowledge of the pathologic diagnosis. The analysis compared the thickness and enhancement pattern of the cyst wall, attenuation of the cyst content, size and shape of the cyst, and paraaortic lymphadenopathy. RESULTS: Mean thickness of the cyst wall was 6.2+/-2.0 mm in TOA and 4.5+/-2.4 mm in endometriosis. Multilayered appearance in both diseases was seen on enhanced CT in 91% (10/11) of TOA cases and in 25% (9/36) of endometriosis cases. Hounsefield units of the cyst contents were 20.0+/-5.5 HU and 24.7+/-10.0 HU for TOA and endometriosis, respectively. Mean diameter of the cysts was 7.5+/-1.7 cm in TOA and 7.9+/-3.1 in endometriosis. Shape of the cyst was multilocular in 82% (9/11) of TOA cases and in 75% (27/36) of endometriosis cases. Paraaortic lymphadenopathy was present in 73% (8/11) and 44% (16/36) for TOA and endometriosis, respectively. CONCLUSION: TOA should be suspected on CT when a multilocular cystic ovarian mass is observed, especially if the lesion has a thick wall and has a multilayered appearance, and is accompanied by paraaortic lymphadenopathy.