Application of artificial intelligence in chest imaging for COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has threatened public health. Medical imaging tools such as chest X-ray and computed tomography (CT) play an essential role in the global fight against COVID-19. Recently emerging artificial intelligence (AI) technologies further strengthen the power of imaging tools and help medical professionals. We reviewed the current progress in the development of AI technologies for the diagnostic imaging of COVID-19.Current Concepts: The rapid development of AI, including deep learning, has led to the development of technologies that may assist in the diagnosis and treatment of diseases, prediction of disease risk and prognosis, health index monitoring, and drug development. In the era of the COVID-19 pandemic, AI can improve work efficiency through accurate delineation of infections on chest X-ray and CT images, differentiation of COVID-19 from other diseases, and facilitation of subsequent disease quantification. Moreover, computer-aided platforms help radiologists make clinical decisions for disease diagnosis, tracking, and prognosis.Discussion and Conclusion: We reviewed the current progress in AI technology for chest imaging for COVID-19. However, it is necessary to combine clinical experts’ observations, medical image data, and clinical and laboratory findings for reliable and efficient diagnosis and management of COVID-19. Future AI research should focus on multimodality-based models and how to select the best model architecture for COVID-19 diagnosis and management.

Mesenchymal Stem Cell and MicroRNA Therapy of Musculoskeletal Diseases

The therapeutic effects of mesenchymal stem cells (MSCs) in musculoskeletal diseases (MSDs) have been verified in many human and animal studies. Although some tissues contain MSCs, the number of cells harvested from those tissues and rate of proliferation in vitro are not enough for continuous transplantation. In order to produce and maintain stable MSCs, many attempts are made to induce differentiation from pluripotent stem cells (iPSCs) into MSCs. In particular, it is also known that the paracrine action of stem cell-secreted factors could promote the regeneration and differentiation of target cells in damaged tissue. MicroRNAs (miRNAs), one of the secreted factors, are small non-coding RNAs that regulate the translation of a gene. It is known that miRNAs help communication between stem cells and their surrounding niches through exosomes to regulate the proliferation and differentiation of stem cells. While studies have so far been underway targeting therapeutic miRNAs of MSDs, studies on specific miRNAs secreted from MSCs are still minimal. Hence, our ultimate goal is to obtain sufficient amounts of exosomes from iPSC-MSCs and develop them into therapeutic agents, furthermore to select specific miRNAs and provide safe cell-free clinical setting as a cell-free status with purpose of delivering them to target cells. This review article focuses on stem cell therapy on MSDs, specific microRNAs regulating MSDs and updates on novel approaches.

Mesenchymal Stem Cell and MicroRNA Therapy of Musculoskeletal Diseases

The therapeutic effects of mesenchymal stem cells (MSCs) in musculoskeletal diseases (MSDs) have been verified in many human and animal studies. Although some tissues contain MSCs, the number of cells harvested from those tissues and rate of proliferation in vitro are not enough for continuous transplantation. In order to produce and maintain stable MSCs, many attempts are made to induce differentiation from pluripotent stem cells (iPSCs) into MSCs. In particular, it is also known that the paracrine action of stem cell-secreted factors could promote the regeneration and differentiation of target cells in damaged tissue. MicroRNAs (miRNAs), one of the secreted factors, are small non-coding RNAs that regulate the translation of a gene. It is known that miRNAs help communication between stem cells and their surrounding niches through exosomes to regulate the proliferation and differentiation of stem cells. While studies have so far been underway targeting therapeutic miRNAs of MSDs, studies on specific miRNAs secreted from MSCs are still minimal. Hence, our ultimate goal is to obtain sufficient amounts of exosomes from iPSC-MSCs and develop them into therapeutic agents, furthermore to select specific miRNAs and provide safe cell-free clinical setting as a cell-free status with purpose of delivering them to target cells. This review article focuses on stem cell therapy on MSDs, specific microRNAs regulating MSDs and updates on novel approaches.

Establishment of a Nationwide Korean Imaging Cohort of Coronavirus Disease 2019

Background@#The Korean Society of Thoracic Radiology (KSTR) recently constructed a nation-wide coronavirus disease 2019 (COVID-19) database and imaging repository, referred to the Korean imaging cohort of COVID-19 (KICC-19) based on the collaborative efforts of its members. The purpose of this study was to provide a summary of the clinico-epidemiological data and imaging data of the KICC-19. @*Methods@#The KSTR members at 17 COVID-19 referral centers retrospectively collected imaging data and clinical information of consecutive patients with reverse transcription polymerase chain reaction-proven COVID-19 in respiratory specimens from February 2020 through May 2020 who underwent diagnostic chest computed tomography (CT) or radiograph in each participating hospital. @*Results@#The cohort consisted of 239 men and 283 women (mean age, 52.3 years; age range, 11–97 years). Of the 522 subjects, 201 (38.5%) had an underlying disease. The most common symptoms were fever (n = 292) and cough (n = 245). The 151 patients (28.9%) had lymphocytopenia, 86 had (16.5%) thrombocytopenia, and 227 patients (43.5%) had an elevated CRP at admission. The 121 (23.4%) needed nasal oxygen therapy or mechanical ventilation (n = 38; 7.3%), and 49 patients (9.4%) were admitted to an intensive care unit.Although most patients had cured, 21 patients (4.0%) died. The 465 (89.1%) subjects underwent a low to standard-dose chest CT scan at least once during hospitalization, resulting in a total of 658 CT scans. The 497 subjects (95.2%) underwent chest radiography at least once during hospitalization, which resulted in a total of 1,475 chest radiographs. @*Conclusion@#The KICC-19 was successfully established and comprised of 658 CT scans and 1,475 chest radiographs of 522 hospitalized Korean COVID-19 patients. The KICC-19 will provide a more comprehensive understanding of the clinical, epidemiological, and radiologic characteristics of patients with COVID-19.

Solitary Nodular Invasive Mucinous Adenocarcinoma of the Lung: Imaging Diagnosis Using the Morphologic-Metabolic Dissociation Sign

OBJECTIVE: To evaluate the efficacy of the morphologic-metabolic (M-M) dissociation sign based on computed tomography (CT) and fluorine-18-fluorodeoxyglucose positron emission tomography (PET)/CT in discriminating invasive mucinous adenocarcinoma (IMA) from invasive non-mucinous adenocarcinomas (ADCs) of the lung. MATERIALS AND METHODS: The Institutional Review Board approved this retrospective study. Among surgically resected solitary pulmonary nodule (SPN)-type ADCs (< 3 cm in diameter), 35 patients with IMAs and 329 with invasive non-mucinous ADCs were included. Morphologic malignancy was established if the tumor with lobulated or spiculated margin on CT presented a tumor shadow disappearance rate of < 0.5. The M-M dissociation sign was determined when a malignant-morphologic nodule on CT showed maximum standardized uptake value (SUVmax) < 3.5 on PET/CT. RESULTS: Among 35 IMAs (size: 21 ± 7 mm, SUVmax: 1.8 ± 2.0) and 329 invasive non-mucinous ADCs (size: 21 ± 6 mm, SUVmax: 4.6 ± 4.2), the M-M dissociation sign was observed in 54% of IMAs (19/35) and 10% of invasive non-mucinous ADCs (34/329) (p < 0.001). The diagnostic performance of the sign in discriminating IMA from invasive non-mucinous ADCs showed a sensitivity of 54.3% (95% confidence interval [CI], 36.7–71.2), specificity 89.7% (95% CI, 85.9–92.7), positive predictive value 35.8% (95% CI, 26.5–46.5), and negative predictive value 94.9% (95% CI, 92.8–96.4). Multivariate analyses revealed metabolic benignity (odds ratio [OR] 2.99; 95% CI, 1.01–8.93; p = 0.047) and M-M dissociation sign (OR 6.35; 95% CI, 2.76–14.62; p < 0.001) to be significant predictors of SPN-type IMAs. CONCLUSION: Identification of the absence of M-M dissociation sign is an accurate indicator for excluding IMA from SPN-type lung ADCs.

Broncho-Pleural Fistula with Hydropneumothorax at CT: Diagnostic Implications in Mycobacterium avium Complex Lung Disease with Pleural Involvement

OBJECTIVE: To determine the patho-mechanism of pleural effusion or hydropneumothorax in Mycobacterium avium complex (MAC) lung disease through the computed tomographic (CT) findings. MATERIALS AND METHODS: We retrospectively collected data from 5 patients who had pleural fluid samples that were culture-positive for MAC between January 2001 and December 2013. The clinical findings were investigated and the radiological findings on chest CT were reviewed by 2 radiologists. RESULTS: The 5 patients were all male with a median age of 77 and all had underlying comorbid conditions. Pleural fluid analysis revealed a wide range of white blood cell counts (410-100690/microL). The causative microorganisms were determined as Mycobacterium avium and Mycobacterium intracellulare in 1 and 4 patients, respectively. Radiologically, the peripheral portion of the involved lung demonstrated fibro-bullous changes or cavitary lesions causing lung destruction, reflecting the chronic, insidious nature of MAC lung disease. All patients had broncho-pleural fistulas (BPFs) and pneumothorax was accompanied with pleural effusion. CONCLUSION: In patients with underlying MAC lung disease who present with pleural effusion, the presence of BPFs and pleural air on CT imaging are indicative that spread of MAC infection is the cause of the effusion.

Avoiding student infection during a Middle East respiratory syndrome (MERS) outbreak: a single medical school experience / 한국의학교육

PURPOSE: In outbreaks of infectious disease, medical students are easily overlooked in the management of healthcare personnel protection although they serve in clinical clerkships in hospitals. In the early summer of 2015, Middle East respiratory syndrome (MERS) struck South Korea, and students of Sungkyunkwan University School of Medicine (SKKUSOM) were at risk of contracting the disease. The purpose of this report is to share SKKUSOM's experience against the MERS outbreak and provide suggestions for medical schools to consider in the face of similar challenges. METHODS: Through a process of reflection-on-action, we examined SKKUSOM's efforts to avoid student infection during the MERS outbreak and derived a few practical guidelines that medical schools can adopt to ensure student safety in outbreaks of infectious disease. RESULTS: The school leadership conducted ongoing risk assessment and developed contingency plans to balance student safety and continuity in medical education. They rearranged the clerkships to another hospital and offered distant lectures and tutorials. Five suggestions are extracted for medical schools to consider in infection outbreaks: instant cessation of clinical clerkships; rational decision making on a school closure; use of information technology; constant communication with hospitals; and open communication with faculty, staff, and students. CONCLUSION: Medical schools need to take the initiative and actively seek countermeasures against student infection. It is essential that medical schools keep constant communication with their index hospitals and the involved personnel. In order to assure student learning, medical schools may consider offering distant education with online technology.

Virtual Non-Contrast CT Using Dual-Energy Spectral CT: Feasibility of Coronary Artery Calcium Scoring

OBJECTIVE: To evaluate the feasibility of coronary artery calcium scoring based on three virtual noncontrast-enhanced (VNC) images derived from single-source spectral dual-energy CT (DECT) as compared with true noncontrast-enhanced (TNC) images. MATERIALS AND METHODS: This prospective study was conducted with the approval of our Institutional Review Board. Ninety-seven patients underwent noncontrast CT followed by contrast-enhanced chest CT using single-source spectral DECT. Iodine eliminated VNC images were reconstructed using two kinds of 2-material decomposition algorithms (material density iodine-water pair [MDW], material density iodine-calcium pair [MDC]) and a material suppressed algorithm (material suppressed iodine [MSI]). Two readers independently quantified calcium on VNC and TNC images. The Spearman correlation coefficient test and Bland-Altman method were used for statistical analyses. RESULTS: Coronary artery calcium scores from all three VNC images showed excellent correlation with those from the TNC images (Spearman's correlation coefficient [ρ] = 0.94, 0.88, and 0.89 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Measured coronary calcium volumes from VNC images also correlated well with those from TNC images (ρ = 0.92, 0.87, and 0.91 for MDW, MDC, and MSI, respectively; p < 0.001 for all pairs). Among the three VNC images, coronary calcium from MDW correlated best with that from TNC. The coronary artery calcium scores and volumes were significantly lower from the VNC images than from the TNC images (p < 0.001 for all pairs). CONCLUSION: The use of VNC images from contrast-enhanced CT using dual-energy material decomposition/suppression is feasible for coronary calcium scoring. The absolute value from VNC tends to be smaller than that from TNC.

Clinical Features and Radiological Findings of Adenovirus Pneumonia Associated with Progression to Acute Respiratory Distress Syndrome: A Single Center Study in 19 Adult Patients

OBJECTIVE: To describe radiologic findings of adenovirus pneumonia and to understand clinico-radiological features associated with progression to acute respiratory distress syndrome (ARDS) in patients with adenovirus pneumonia. MATERIALS AND METHODS: This study included 19 patients diagnosed with adenovirus pneumonia at a tertiary referral center, in the period between March 2003 and April 2015. Clinical findings were reviewed, and two radiologists assessed imaging findings by consensus. Chi-square, Fisher's exact, and Student's t tests were used for comparing patients with and without subsequent development of ARDS. RESULTS: Of 19 patients, nine were immunocompromised, and 10 were immunocompetent. Twelve patients (63%) progressed to ARDS, six of whom (32%) eventually died from the disease. The average time for progression to ARDS from symptom onset was 9.6 days. Initial chest radiographic findings were normal (n = 2), focal opacity (n = 9), or multifocal or diffuse opacity (n = 8). Computed tomography (CT) findings included bilateral (n = 17) or unilateral (n = 2) ground-glass opacity with consolidation (n = 14) or pleural effusion (n = 11). Patients having subsequent ARDS had a higher probability of pleural effusion and a higher total CT extent compared with the non-ARDS group (p = 0.010 and 0.007, respectively). However, there were no significant differences in clinical variables such as patient age and premorbid condition. CONCLUSION: Adenovirus pneumonia demonstrates high rates of ARDS and mortality, regardless of patient age and premorbid conditions, in the tertiary care setting. Large disease extent and presence of pleural effusion on CT are factors suggestive of progression to ARDS.

The Impact of Iterative Reconstruction in Low-Dose Computed Tomography on the Evaluation of Diffuse Interstitial Lung Disease

OBJECTIVE: To evaluate the impact of iterative reconstruction (IR) on the assessment of diffuse interstitial lung disease (DILD) using CT. MATERIALS AND METHODS: An American College of Radiology (ACR) phantom (module 4 to assess spatial resolution) was scanned with 10–100 effective mAs at 120 kVp. The images were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), with blending ratios of 0%, 30%, 70% and 100%, and model-based iterative reconstruction (MBIR), and their spatial resolution was objectively assessed by the line pair structure method. The patient study was based on retrospective interpretation of prospectively acquired data, and it was approved by the institutional review board. Chest CT scans of 23 patients (mean age 64 years) were performed at 120 kVp using 1) standard dose protocol applying 142–275 mA with dose modulation (high-resolution computed tomography [HRCT]) and 2) low-dose protocol applying 20 mA (low dose CT, LDCT). HRCT images were reconstructed with FBP, and LDCT images were reconstructed using FBP, ASIR, and MBIR. Matching images were randomized and independently reviewed by chest radiologists. Subjective assessment of disease presence and radiological diagnosis was made on a 10-point scale. In addition, semi-quantitative results were compared for the extent of abnormalities estimated to the nearest 5% of parenchymal involvement. RESULTS: In the phantom study, ASIR was comparable to FBP in terms of spatial resolution. However, for MBIR, the spatial resolution was greatly decreased under 10 mA. In the patient study, the detection of the presence of disease was not significantly different. The values for area under the curve for detection of DILD by HRCT, FBP, ASIR, and MBIR were as follows: 0.978, 0.979, 0.972, and 0.963. LDCT images reconstructed with FBP, ASIR, and MBIR tended to underestimate reticular or honeycombing opacities (-2.8%, -4.1%, and -5.3%, respectively) and overestimate ground glass opacities (+4.6%, +8.9%, and +8.5%, respectively) compared to the HRCT images. However, the reconstruction methods did not differ with respect to radiologic diagnosis. CONCLUSION: The diagnostic performance of LDCT with MBIR was similar to that of HRCT in typical DILD cases. However, caution should be exercised when comparing disease extent, especially in follow-up studies with IR.

Isolated Endobronchial Mycobacterium avium Disease Associated with Lobar Atelectasis in an Immunocompetent Young Adult: A Case Report and Literature Review / 결핵및호흡기질환

The prevalence of lung diseases caused by nontuberculous mycobacteria (NTM) is increasing worldwide. Unlike pulmonary tuberculosis, endobronchial NTM diseases are very rare with the majority of cases reported in patients with human immunodeficiency virus infection and acquired immune deficiency syndrome. We reported a rare case of endobronchial Mycobacterium avium disease associated with lobar atelectasis in a young immunocompetent patient and reviewed the relevant iterature.

Nontuberculous Mycobacterial Lung Disease Caused by Mycobacterium shinjukuense: The First Reported Case in Korea / 결핵및호흡기질환

Mycobacterium shinjukuense is a novel species of nontuberculous mycobacteria (NTM) that was first reported in Japan in 2011. It is a slow-growing NTM pathogen that can cause chronic pulmonary infections. There are only a few reported cases of M. shinjukuense infections, all of which are from Japan. We reported a case of chronic lung disease caused by M. shinjukuense. The organism was identified by 16S rRNA, rpoB, and hsp65 gene sequencing. To the best of our knowledge, this was the first confirmed case of lung disease caused by M. shinjukuense outside of Japan.

Nontuberculous Mycobacterial Lung Disease Caused by Mycobacterium simiae: The First Reported Case in South Korea / 결핵및호흡기질환

This is a report of the first South Korean case of a lung disease caused by Mycobacterium simiae. The patient was a previously healthy 52-year-old female. All serial isolates were identified as M. simiae by multi-locus sequencing analysis, based on hsp65, rpoB, 16S-23S rRNA internal transcribed spacer, and 16S rRNA fragments. A chest radiography revealed deterioration, and the follow-up sputum cultures were persistently positive, despite combination antibiotic treatment, including azithromycin, ethambutol, and rifampin. To the best of our knowledge, this is the first confirmed case of a lung disease caused by M. simiae in South Korea.

Adaptive Statistical Iterative Reconstruction-Applied Ultra-Low-Dose CT with Radiography-Comparable Radiation Dose: Usefulness for Lung Nodule Detection

OBJECTIVE: To assess the performance of adaptive statistical iterative reconstruction (ASIR)-applied ultra-low-dose CT (ULDCT) in detecting small lung nodules. MATERIALS AND METHODS: Thirty patients underwent both ULDCT and standard dose CT (SCT). After determining the reference standard nodules, five observers, blinded to the reference standard reading results, independently evaluated SCT and both subsets of ASIR- and filtered back projection (FBP)-driven ULDCT images. Data assessed by observers were compared statistically. RESULTS: Converted effective doses in SCT and ULDCT were 2.81 +/- 0.92 and 0.17 +/- 0.02 mSv, respectively. A total of 114 lung nodules were detected on SCT as a standard reference. There was no statistically significant difference in sensitivity between ASIR-driven ULDCT and SCT for three out of the five observers (p = 0.678, 0.735, < 0.01, 0.038, and < 0.868 for observers 1, 2, 3, 4, and 5, respectively). The sensitivity of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT in three out of the five observers (p < 0.01 for three observers, and p = 0.064 and 0.146 for two observers). In jackknife alternative free-response receiver operating characteristic analysis, the mean values of figure-of-merit (FOM) for FBP, ASIR-driven ULDCT, and SCT were 0.682, 0.772, and 0.821, respectively, and there were no significant differences in FOM values between ASIR-driven ULDCT and SCT (p = 0.11), but the FOM value of FBP-driven ULDCT was significantly lower than that of ASIR-driven ULDCT and SCT (p = 0.01 and 0.00). CONCLUSION: Adaptive statistical iterative reconstruction-driven ULDCT delivering a radiation dose of only 0.17 mSv offers acceptable sensitivity in nodule detection compared with SCT and has better performance than FBP-driven ULDCT.

Digital Tomosynthesis of the Chest: Comparison of Patient Exposure Dose and Image Quality between Standard Default Setting and Low Dose Setting

OBJECTIVE: To determine the optimum low dose (LD) digital tomosynthesis (DT) setting, and to compared the image quality of the LD DT with that of the standard default (SD) DT. MATERIALS AND METHODS: Nine DT settings, by changing tube voltage, copper filter, and dose ratio, were performed for determining the LD setting. Among combinations of DT setting, a condition providing the lowest radiation dose was determined. Eighty artificial nodules less than 1 cm in diameter (subcentimeter nodules: 40, micronodules less than 4 mm: 40) were attached to a Styrofoam and a diaphragm of the phantom. Among these, 38 nodules were located at the periphery of the lung (thin area) and 42 nodules were located at the paravertebral or sub-diaphragmatic area (thick area). Four observers counted the number of nodules detected in the thick and thin areas. The detection sensitivity in SD and LD settings were calculated separately. Data were analyzed statistically. RESULTS: The lowest LD setting was a combination of 100 kVp, 0.3 mm additional copper filter, and a 1 : 5 dose ratio. The effective dose for the LD and SD settings were 62 microSv and 140 microSv, separately. A 56.7% dose reduction was achieved in the LD setting compared with the SD setting. Detection sensitivities were not different between the SD and the LD settings except between observers 1 and 2 for the detection of micronodules in the thick area. CONCLUSION: LD DT can be effective in nodule detection bigger than 4 mm without a significant decrease in image quality compared with SD DT.

Interpretation of Digital Chest Radiographs: Comparison of Light Emitting Diode versus Cold Cathode Fluorescent Lamp Backlit Monitors

OBJECTIVE: To compare the diagnostic performance of light emitting diode (LED) backlight monitors and cold cathode fluorescent lamp (CCFL) monitors for the interpretation of digital chest radiographs. MATERIALS AND METHODS: We selected 130 chest radiographs from health screening patients. The soft copy image data were randomly sorted and displayed on a 3.5 M LED (2560 x 1440 pixels) monitor and a 3 M CCFL (2048 x 1536 pixels) monitor. Eight radiologists rated their confidence in detecting nodules and abnormal interstitial lung markings (ILD). Low dose chest CT images were used as a reference standard. The performance of the monitor systems was assessed by analyzing 2080 observations and comparing them by multi-reader, multi-case receiver operating characteristic analysis. The observers reported visual fatigue and a sense of heat. Radiant heat and brightness of the monitors were measured. RESULTS: Measured brightness was 291 cd/m2 for the LED and 354 cd/m2 for the CCFL monitor. Area under curves for nodule detection were 0.721 +/- 0.072 and 0.764 +/- 0.098 for LED and CCFL (p = 0.173), whereas those for ILD were 0.871 +/- 0.073 and 0.844 +/- 0.068 (p = 0.145), respectively. There were no significant differences in interpretation time (p = 0.446) or fatigue score (p = 0.102) between the two monitors. Sense of heat was lower for the LED monitor (p = 0.024). The temperature elevation was 6.7degrees C for LED and 12.4degrees C for the CCFL monitor. CONCLUSION: Although the LED monitor had lower maximum brightness compared with the CCFL monitor, soft copy reading of the digital chest radiographs on LED and CCFL showed no difference in terms of diagnostic performance. In addition, LED emitted less heat.

Digital Tomosynthesis for PNS Evaluation: Comparisons of Patient Exposure and Image Quality with Plain Radiography

OBJECTIVE: We investigated low dose digital tomosynthesis (DT) for the evaluation of the paranasal sinus (PNS), and compared its diagnostic accuracy with a PNS radiography series (XR). MATERIALS AND METHODS: We enrolled 43 patients for whom XR, PNS DT, and OMU CT were performed. We measured effective doses (EDs) of XR, DT, and OMU CT using Monte Carlo simulation software. Two radiologists performed independent observation of both XR and DT. For seven PNSs, they scored anatomic conspicuity of sinuses and confidence on the presence of sinusitis using nine point scales. OMU CT was observed by the third radiologist and the findings were regarded as reference standard. We compared scores for conspicuity and sinusitis confidence between XR and DT. RESULTS: Mean EDs were 29 +/- 6 microSv, 48 +/- 10 microSv, and 980 +/- 250 microSv, respectively, for XR, DT, and CT. Mean scores for conspicuity were 6.3 and 7.4, respectively, for XR and DT. Sensitivity per patient basis for sinusitis detection were 52% and 96%, respectively, for XR and DT in observer 1 (p = 0.001) and 80% and 92% for observer 2 (p = 0.25). Specificities for sinusitis exclusion were 100% for both XR and DT for observer 1 and 89% and 100% for observer 2 (p = 0.50). Accuracies for sinusitis diagnosis were 72% and 98%, respectively, for XR and DT for observer 1 (p = 0.001) and 84% and 95% for observer 2 (p = 0.125). CONCLUSION: Patient radiation dose from low dose DT is comparable with that of PNS XR. Diagnostic sensitivity of DT for sinusitis was superior to PNS XR.

Dual-Energy CT in Patients Treated with Anti-Angiogenic Agents for Non-Small Cell Lung Cancer: New Method of Monitoring Tumor Response?

OBJECTIVE: To evaluate tumor responses in patients treated with anti-angiogenic agents for non-small cell lung cancer (NSCLC) by assessing intratumoral changes using a dual-energy CT (DECT) (based on Choi's criteria) and to compare it to traditional Response Evaluation Criteria in Solid Tumors (RECIST) criteria. MATERIALS AND METHODS: Ten NSCLC patients treated with bevacizumab underwent DECT. Tumor responses to anti-angiogenic therapy were assessed and compared with the baseline CT results using both RECIST (size changes only) and Choi's criteria (reflecting net tumor enhancement). Kappa statistics was used to evaluate agreements between tumor responses assessed by RECIST and Choi's criteria. RESULTS: The weighted kappa value for the comparison of tumor responses between the RECIST and Choi's criteria was 0.72. Of 31 target lesions (21 solid nodules, 8 lymph nodes, and two ground-glass opacity nodules [GGNs]), five lesions (16%) showed discordant responses between RECIST and Choi's criteria. Iodine-enhanced images allowed for a distinction between tumor enhancement and hemorrhagic response (detected in 14% [4 of 29, excluding GGNs] of target lesions on virtual nonenhanced images). CONCLUSION: DECT may serve as a useful tool for response evaluation after anti-angiogenic treatment in NSCLC patients by providing information on the net enhancement of target lesions without obtaining non-enhanced images.

Usefulness of the CAD System for Detecting Pulmonary Nodule in Real Clinical Practice

OBJECTIVE: We wanted to evaluate the usefulness of the computer-aided detection (CAD) system for detecting pulmonary nodules in real clinical practice by using the CT images. MATERIALS AND METHODS: Our Institutional Review Board approved our retrospective study with a waiver of informed consent. This study included 166 CT examinations that were performed for the evaluation of pulmonary metastasis in 166 patients with colorectal cancer. All the CT examinations were interpreted by radiologists and they were also evaluated by the CAD system. All the nodules detected by the CAD system were evaluated with regard to whether or not they were true nodules, and they were classified into micronodules (MN, diameter < 4 mm) and significant nodules (SN, 4 < or = diameter < or = 10 mm). The radiologic reports and CAD results were compared. RESULTS: The CAD system helped detect 426 nodules; 115 (27%) of the 426 nodules were classified as true nodules and 35 (30%) of the 115 nodules were SNs, and 83 (72%) of the 115 were not mentioned in the radiologists' reports and three (4%) of the 83 nodules were non-calcified SNs. One of three non-calcified SNs was confirmed as a metastatic nodule. According to the radiologists' reports, 60 true nodules were detected, and 28 of the 60 were not detected by the CAD system. CONCLUSION: Although the CAD system missed many SNs that are detected by radiologists, it helps detect additional nodules that are missed by the radiologists in real clinical practice. Therefore, the CAD system can be useful to support a radiologist's detection performance.

Pulmonary Cryptococcosis: Imaging Findings in 23 Non-AIDS Patients

OBJECTIVE: We aimed to review the patterns of lung abnormalities of pulmonary cryptococcosis on CT images, position emission tomography (PET) findings of the disease, and the response of lung abnormalities to the therapies in non-AIDS patients. MATERIALS AND METHODS: We evaluated the initial CT (n = 23) and 18F-fluorodeoxyglucose (FDG) PET (n = 10), and follow-up (n = 23) imaging findings of pulmonary cryptococcosis in 23 non-AIDS patients. Lung lesions were classified into five patterns at CT: single nodular, multiple clustered nodular, multiple scattered nodular, mass-like, and bronchopneumonic patterns. The CT pattern analyses, PET findings, and therapeutic responses were recorded. RESULTS: A clustered nodular pattern was the most prevalent and was observed in 10 (43%) patients. This pattern was followed by solitary pulmonary nodular (n = 4, 17%), scattered nodular (n = 3, 13%), bronchopneumonic (n = 2, 9%), and single mass (n = 1, 4%) patterns. On PET scans, six (60%) of 10 patients showed higher FDG uptake and four (40%) demonstrated lower FDG uptake than the mediastinal blood pool. With specific treatment of the disease, a complete clearance of lung abnormalities was noted in 15 patients, whereas a partial response was noted in seven patients. In one patient where treatment was not performed, the disease showed progression. CONCLUSION: Pulmonary cryptococcosis most commonly appears as clustered nodules and is a slowly progressive and slowly resolving pulmonary infection. In two-thirds of patients, lung lesions show high FDG uptake, thus simulating a possible malignant condition.