Radiology

The day when computers read between lines Abstract There is a growing notion that artificial general intelligence (AGI) will replace some of the work done by trained professionals, including physicians. This idea, however, seems to have logical leap; herein, we discuss three problems that are significant barriers to this. First, the ground truth is difficult to provide in the majority of medical conditions. Second, the electronic medical record (EMR) only covers a portion of the information that is crucial for patient care. This makes the data in the EMR a suboptimum material for creation of AGI. Third, there are decision-making processes that cannot be captured in a way that computers can digest; portions of our thoughts, perceptions, intuitions, and inspirations cannot be translated into numbers or words.

Imaging findings of mixed connective tissue disease in children and adolescents: a case series Abstract Mixed connective tissue disease (MCTD) is a rare disease in children and adolescents which overlaps features of juvenile idiopathic arthritis, polymyositis/dermatomyositis, systemic lupus erythematosus, and systemic sclerosis. We have provided an image-based approach for evaluation of MCTD in children and adolescents, outlying the most frequent imaging findings. This approach would aid imagers and clinicians to consider the diagnosis of this rare entity and be able to make an accurate list of differential diagnosis for complex rheumatologic diseases such as MCTD, thus facilitating the ultimate goal of early diagnosis and optimal management of affected children.

Liver assessment using Gd-EOB-DTPA-enhanced magnetic resonance imaging in primary biliary cholangitis patients Abstract Purpose To evaluate the feasibility of utilizing gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for the assessment of Child–Pugh class and for differentiating between patients with primary biliary cholangitis (PBC) and posthepatitic cirrhosis. Materials and methods 45 PBC patients and 45 posthepatitic cirrhosis patients were enrolled and Gd-EOB-DTPA-enhanced MRI was applied. The average relative signal enhancement (RE) of the liver and average contrast to noise ratio (CNR) of common bile duct at 4, 20, and 50 min between different Child–Pugh classes of PBC patients were compared. The RE and CNR in all timepoints in patients with the same Child–Pugh class were compared between PBC patients and posthepatitic cirrhosis patients. Results The RE of liver and CNR of common bile duct at 4, 20, and 50 min was significantly different between all Child–Pugh classes of PBC patients. There were also no significant differences in the RE of liver and CNR of common bile duct in all timepoints between patients with PBC and posthepatitic cirrhosis in the same Child–Pugh class. Conclusion Gd-EOB-DTPA-enhanced MRI is feasible for liver function assessment in PBC patients. However, the ability of this modality in differentiating liver cirrhosis of different etiologies requires further investigation.

Airway quantification using adaptive statistical iterative reconstruction-V on wide-detector low-dose CT: a validation study on lung specimen Abstract Purpose To evaluate the accuracy of airway quantification of adaptive statistical iterative reconstruction (ASIR)-V on low-dose CT using a human lung specimen. Method A lung specimen was scanned on Revolution CT with low-dose settings (20 mAs, 40 mAs and 60 mAs/100 kV) and standard-dose setting (100 mAs/120 kV). CT images were reconstructed using lung kernel with eleven ASIR-V levels from 0 to 100% with 10% interval. ASIR-V level from 0 to 100% with 10% interval was reconstructed on lung kernel. Wall area percentage (%WA) and wall thickness (WT) were measured. Results Radiation dose of 20 mAs, 40 mAs and 60 mAs low-dose settings reduced by 87.6%, 75.2% and 62.8% compared to that on standard dose, respectively. Low-dose settings significantly decreased image SNR (p < 0.05) and increased noise (p < 0.001). ASIR-V level exponentially improved image SNR and linearly decreased image noise (all p < 0.001). The mean airway measurement ratios of low-dose to standard-dose were within 2% variation for %WA and within 3% variation for WT. Most %WA and WT values showed no obvious correlation with ASIR-V levels. Conclusion ASIR-V showed to improve image quality in low radiation dose. However, low-dose settings and ASIR-V strength did not significantly influence airway quantification values, although variation in measurements slightly increased with dose reduction.

CT features of parathyroid carcinomas: comparison with benign parathyroid lesions Abstract Purpose To describe CT features of parathyroid carcinomas (PCs) by comparison with benign parathyroid lesions (BPs). Methods This retrospective study comprised 82 patients with 76 BPs (62 adenomas and 14 hyperplastic lesions) and 6 PCs. CT features (size, short-to-long axis ratio, shape, peritumoral infiltration, homogeneity, calcification, attenuation values on unenhanced CT, and contrast enhancement during arterial and venous phases) were compared between PCs and BPs. The diagnostic performance of CT features for diagnosing PCs was calculated for these individual parameters. Results Short-to-long axis ratio was significantly larger in PCs (0.7 ± 0.1) than in BPs (0.5 ± 0.1, p = 0.004). Irregular shape (33%), the presence of peritumoral infiltration (50%), and calcification (33%) were significantly more common in PCs than BPs. The contrast enhancement value was significantly lower in PCs than BPs during arterial (p = 0.004) and venous phases (p = 0.044). The 100% sensitivity criterion for the short-to-long axis ratio (≥ 0.53), enhancement during arterial phase (≤ 56.6HU), and venous phase (≤ 59.5HU) yielded accuracies (62.1%, 71.9%, and 75.4%, respectively). Irregular shape, peritumoral infiltration, and calcification showed high specificity (98.7%) and accuracy (93.9%, 95.1%, and 93.9%, respectively). Conclusions CT features of high short-to-long axis ratio, irregular shape, the presence of peritumoral infiltration and calcification, and low contrast enhancement may aid in distinguishing PCs from BPs.

Imaging of extracranial head and neck lesions in cancer patients: a symptom-based approach Abstract Besides intracranial lesions, neurological symptoms are also caused in cancer patients by extracranial lesions in the head and neck. Common symptoms caused by such lesions include visual loss, visual field defect, diplopia, ptosis, sensory abnormalities of the head and neck region, facial nerve palsy, dysphagia, dysarthria, hoarseness, and syncope. Some cancer patients often have multiple cranial nerve involvement, which is associated with several syndromes such as jugular foramen syndrome. The main causes of cranial nerve dysfunction due to extracranial lesions include bone and nodal metastasis, perineural tumor spread, inflammation, and radiation injury. The location of the lesions causing the neurological symptom may be estimated by the symptoms and physical examination. However, CT/MRI is critical for reaching the final diagnosis and for treatment planning and management of the cancer patients. Moreover, early identification of the extracranial lesions may significantly affect patient care and alter outcomes. Thus, radiologists should be familiar with imaging findings of the common neurological disorders and the complex anatomy of the head and neck region, which should be checked in cancer patients with neurological symptoms.

Increased signal intensity of low-concentration gadolinium contrast agent by longer repetition time in heavily T 2 -weighted-3D-FLAIR Abstract Purpose To apply for detecting low-concentration gadolinium contrast agent (Gd), such as those in the perilymph and cerebrospinal fluid (CSF) at 4 h after intravenous administrations (IV), we tried to clarify the degree of increased signal intensity (SI) of low-concentration Gd by longer repetition time (TR) in heavily T2-weighed 3D-FLAIR. Materials and methods A phantom was designed using Gd diluted with saline at 0.250–0.008 mM and obtained images by varying the TR from 9000 to 16,000. We measured the SI of five slices for each concentration and compared the mean SI (SImean) values. Normalized SI (SInorm) values, defined as the SImean value of each TR divided by the SImean value of 9000-ms TR for each concentration were compared. Results Longer TR increased the SImean values in all solutions. In the 0.250 mM solution, the SImean value of 16,000-ms TR was 1.07-times greater than that of 9000-ms TR. In contrast, the SImean value of 16,000-ms TR was 1.67-times greater than that of 9000-ms TR in 0.008 mM solution. Conclusion SI increased with longer TR and lower Gd concentration. Thus, longer TR was useful in detecting low-concentration Gd, such as those in the perilymph and CSF at 4 h after IV.

Effects of acquisition method and reconstruction algorithm for CT number measurement on standard-dose CT and reduced-dose CT: a QIBA phantom study Abstract Purpose To compare the effect of different acquisition and reconstruction methods on the radiation dose and accuracy of CT number measurements, using a 320-detector row CT and a Quantitative Imaging Biomarker Alliance (QIBA) recommended phantom. Materials and methods Acquisitions were performed on a 320-detector row CT, as 64- and 80-detector row helical and wide detector step-and-shoot (i.e., wide volume) acquisitions with tube currents of 400 mA, 100 mA, 50 mA, 20 mA, and 10 mA. Image was reconstructed with the filtered back projection (FBP), adaptive iterative dose reduction using 3D processing (AIDR 3D), and forward projected model-based iterative reconstruction (FIRST) methods. The difference between measured CT numbers and the actual -856HU value of the phantom insert was determined by each CT acquisition protocol. Differences in actual and measured CT numbers were compared among acquisitions and among reconstruction methods by means of Tukey's HSD test. Results The CT number obtained with 64-detector row helical acquisition was significantly larger than that obtained with others (p < 0.0001). At each tube current, the CT number reconstructed with FIRST was significantly smaller than that with others (p < 0.0001). Conclusion Acquisition and reconstruction methods are significantly affecting radiation dose reduction and accuracy of CT number measurements on a phantom study.

A heart atlas for breast radiation therapy and the influence of delination education on both intra and interobserver variability Abstract Purpose We developed a heart atlas for breast radiation therapy and evaluated the influence of education on intra and inter-observer similarity, and cardiac dose reporting. Materials and methods The data of 16 left breast cancer patients were analyzed. Eight observers delineated heart and cardiac subunits [left (LCA) and right (RCA) coronary arteries, left anterior descending artery (LAD), bilateral atrium and ventricles] before the education. A radiologist and radiation oncologist developed the atlas and delineated the gold standard (GS) volumes. Observers repeated the delineation after education. RT plans were made for pre/post-atlas contours. The similarity was assessed by Dice (DSC) and Jaccard (JSC) similarity coefficient indices. The absolute difference rate was calculated for the dose analysis. Results The inter-observer similarity increased in heart and all subunits. The intra-observer similarity showed a heterogeneous distribution. The absolute difference rate in dose reporting was statistically significant for the bilateral atrium, right ventricle, LAD, LCA + LAD, RCA's maximum doses (p < 0.05). The maximum dose reporting differences from the GS decreased from 16.9 to 8.9% for LAD (p = 0.011); from 14.8 to 9.3% for LCA + LAD (p = 0.010). Conclusion The cardiac atlas reduces the intra-interobserver differences and improves dose reporting consistency. The first intra-observer similarity analysis was made in our study and revealed the need for repeated education to increase the consistency.

Detectability of the choroid plexus of the third ventricle with magnetic resonance ventriculography Abstract Purpose To clarify the detectability of the choroid plexus of the third ventricle (ChPl3V) with magnetic resonance ventriculography (MRVn) employing a steady-state free precession (SSFP) sequence in comparison to surgical endoscopic movies as a golden standard, as we encountered some clinical cases of total agenesis of corpus callosum (ACC) where we could not recognize the choroid plexus of the third ventricle and found no previous article addressing this problem. Materials and methods This retrospective study included consecutive patients from 2010 to 2016 for whom endoscopic evaluation of the third ventricle was conducted. The anterior portion of the right and left streaks of ChPl3V was evaluated in 8 patients on 16 sites, while the posterior portion of both streaks of ChPl3V was evaluated in 13 patients on 26 sites. Sensitivity of MRVn to visualize ChPl3V with endoscopic movies as the golden standard was calculated. Results Sensitivity of MRVn in visualizing the anterior portion of ChPl3V was 0.813, and that for the posterior portion 0.692. The anterior portion of ChPl3V was visualized in all cases where no tumor contacted the foramen of Monro. Conclusion MRVn visualizes the anterior portion of ChPl3V with significant sensitivity and the posterior portion with lower one.